LCOV - code coverage report
Current view: top level - src/backend/utils/mmgr - aset.c (source / functions) Hit Total Coverage
Test: PostgreSQL 13devel Lines: 202 250 80.8 %
Date: 2019-09-19 02:07:14 Functions: 9 10 90.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * aset.c
       4             :  *    Allocation set definitions.
       5             :  *
       6             :  * AllocSet is our standard implementation of the abstract MemoryContext
       7             :  * type.
       8             :  *
       9             :  *
      10             :  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
      11             :  * Portions Copyright (c) 1994, Regents of the University of California
      12             :  *
      13             :  * IDENTIFICATION
      14             :  *    src/backend/utils/mmgr/aset.c
      15             :  *
      16             :  * NOTE:
      17             :  *  This is a new (Feb. 05, 1999) implementation of the allocation set
      18             :  *  routines. AllocSet...() does not use OrderedSet...() any more.
      19             :  *  Instead it manages allocations in a block pool by itself, combining
      20             :  *  many small allocations in a few bigger blocks. AllocSetFree() normally
      21             :  *  doesn't free() memory really. It just add's the free'd area to some
      22             :  *  list for later reuse by AllocSetAlloc(). All memory blocks are free()'d
      23             :  *  at once on AllocSetReset(), which happens when the memory context gets
      24             :  *  destroyed.
      25             :  *              Jan Wieck
      26             :  *
      27             :  *  Performance improvement from Tom Lane, 8/99: for extremely large request
      28             :  *  sizes, we do want to be able to give the memory back to free() as soon
      29             :  *  as it is pfree()'d.  Otherwise we risk tying up a lot of memory in
      30             :  *  freelist entries that might never be usable.  This is specially needed
      31             :  *  when the caller is repeatedly repalloc()'ing a block bigger and bigger;
      32             :  *  the previous instances of the block were guaranteed to be wasted until
      33             :  *  AllocSetReset() under the old way.
      34             :  *
      35             :  *  Further improvement 12/00: as the code stood, request sizes in the
      36             :  *  midrange between "small" and "large" were handled very inefficiently,
      37             :  *  because any sufficiently large free chunk would be used to satisfy a
      38             :  *  request, even if it was much larger than necessary.  This led to more
      39             :  *  and more wasted space in allocated chunks over time.  To fix, get rid
      40             :  *  of the midrange behavior: we now handle only "small" power-of-2-size
      41             :  *  chunks as chunks.  Anything "large" is passed off to malloc().  Change
      42             :  *  the number of freelists to change the small/large boundary.
      43             :  *
      44             :  *-------------------------------------------------------------------------
      45             :  */
      46             : 
      47             : #include "postgres.h"
      48             : 
      49             : #include "utils/memdebug.h"
      50             : #include "utils/memutils.h"
      51             : 
      52             : /* Define this to detail debug alloc information */
      53             : /* #define HAVE_ALLOCINFO */
      54             : 
      55             : /*--------------------
      56             :  * Chunk freelist k holds chunks of size 1 << (k + ALLOC_MINBITS),
      57             :  * for k = 0 .. ALLOCSET_NUM_FREELISTS-1.
      58             :  *
      59             :  * Note that all chunks in the freelists have power-of-2 sizes.  This
      60             :  * improves recyclability: we may waste some space, but the wasted space
      61             :  * should stay pretty constant as requests are made and released.
      62             :  *
      63             :  * A request too large for the last freelist is handled by allocating a
      64             :  * dedicated block from malloc().  The block still has a block header and
      65             :  * chunk header, but when the chunk is freed we'll return the whole block
      66             :  * to malloc(), not put it on our freelists.
      67             :  *
      68             :  * CAUTION: ALLOC_MINBITS must be large enough so that
      69             :  * 1<<ALLOC_MINBITS is at least MAXALIGN,
      70             :  * or we may fail to align the smallest chunks adequately.
      71             :  * 8-byte alignment is enough on all currently known machines.
      72             :  *
      73             :  * With the current parameters, request sizes up to 8K are treated as chunks,
      74             :  * larger requests go into dedicated blocks.  Change ALLOCSET_NUM_FREELISTS
      75             :  * to adjust the boundary point; and adjust ALLOCSET_SEPARATE_THRESHOLD in
      76             :  * memutils.h to agree.  (Note: in contexts with small maxBlockSize, we may
      77             :  * set the allocChunkLimit to less than 8K, so as to avoid space wastage.)
      78             :  *--------------------
      79             :  */
      80             : 
      81             : #define ALLOC_MINBITS       3   /* smallest chunk size is 8 bytes */
      82             : #define ALLOCSET_NUM_FREELISTS  11
      83             : #define ALLOC_CHUNK_LIMIT   (1 << (ALLOCSET_NUM_FREELISTS-1+ALLOC_MINBITS))
      84             : /* Size of largest chunk that we use a fixed size for */
      85             : #define ALLOC_CHUNK_FRACTION    4
      86             : /* We allow chunks to be at most 1/4 of maxBlockSize (less overhead) */
      87             : 
      88             : /*--------------------
      89             :  * The first block allocated for an allocset has size initBlockSize.
      90             :  * Each time we have to allocate another block, we double the block size
      91             :  * (if possible, and without exceeding maxBlockSize), so as to reduce
      92             :  * the bookkeeping load on malloc().
      93             :  *
      94             :  * Blocks allocated to hold oversize chunks do not follow this rule, however;
      95             :  * they are just however big they need to be to hold that single chunk.
      96             :  *
      97             :  * Also, if a minContextSize is specified, the first block has that size,
      98             :  * and then initBlockSize is used for the next one.
      99             :  *--------------------
     100             :  */
     101             : 
     102             : #define ALLOC_BLOCKHDRSZ    MAXALIGN(sizeof(AllocBlockData))
     103             : #define ALLOC_CHUNKHDRSZ    sizeof(struct AllocChunkData)
     104             : 
     105             : typedef struct AllocBlockData *AllocBlock;  /* forward reference */
     106             : typedef struct AllocChunkData *AllocChunk;
     107             : 
     108             : /*
     109             :  * AllocPointer
     110             :  *      Aligned pointer which may be a member of an allocation set.
     111             :  */
     112             : typedef void *AllocPointer;
     113             : 
     114             : /*
     115             :  * AllocSetContext is our standard implementation of MemoryContext.
     116             :  *
     117             :  * Note: header.isReset means there is nothing for AllocSetReset to do.
     118             :  * This is different from the aset being physically empty (empty blocks list)
     119             :  * because we will still have a keeper block.  It's also different from the set
     120             :  * being logically empty, because we don't attempt to detect pfree'ing the
     121             :  * last active chunk.
     122             :  */
     123             : typedef struct AllocSetContext
     124             : {
     125             :     MemoryContextData header;   /* Standard memory-context fields */
     126             :     /* Info about storage allocated in this context: */
     127             :     AllocBlock  blocks;         /* head of list of blocks in this set */
     128             :     AllocChunk  freelist[ALLOCSET_NUM_FREELISTS];   /* free chunk lists */
     129             :     /* Allocation parameters for this context: */
     130             :     Size        initBlockSize;  /* initial block size */
     131             :     Size        maxBlockSize;   /* maximum block size */
     132             :     Size        nextBlockSize;  /* next block size to allocate */
     133             :     Size        allocChunkLimit;    /* effective chunk size limit */
     134             :     AllocBlock  keeper;         /* keep this block over resets */
     135             :     /* freelist this context could be put in, or -1 if not a candidate: */
     136             :     int         freeListIndex;  /* index in context_freelists[], or -1 */
     137             : } AllocSetContext;
     138             : 
     139             : typedef AllocSetContext *AllocSet;
     140             : 
     141             : /*
     142             :  * AllocBlock
     143             :  *      An AllocBlock is the unit of memory that is obtained by aset.c
     144             :  *      from malloc().  It contains one or more AllocChunks, which are
     145             :  *      the units requested by palloc() and freed by pfree().  AllocChunks
     146             :  *      cannot be returned to malloc() individually, instead they are put
     147             :  *      on freelists by pfree() and re-used by the next palloc() that has
     148             :  *      a matching request size.
     149             :  *
     150             :  *      AllocBlockData is the header data for a block --- the usable space
     151             :  *      within the block begins at the next alignment boundary.
     152             :  */
     153             : typedef struct AllocBlockData
     154             : {
     155             :     AllocSet    aset;           /* aset that owns this block */
     156             :     AllocBlock  prev;           /* prev block in aset's blocks list, if any */
     157             :     AllocBlock  next;           /* next block in aset's blocks list, if any */
     158             :     char       *freeptr;        /* start of free space in this block */
     159             :     char       *endptr;         /* end of space in this block */
     160             : }           AllocBlockData;
     161             : 
     162             : /*
     163             :  * AllocChunk
     164             :  *      The prefix of each piece of memory in an AllocBlock
     165             :  *
     166             :  * Note: to meet the memory context APIs, the payload area of the chunk must
     167             :  * be maxaligned, and the "aset" link must be immediately adjacent to the
     168             :  * payload area (cf. GetMemoryChunkContext).  We simplify matters for this
     169             :  * module by requiring sizeof(AllocChunkData) to be maxaligned, and then
     170             :  * we can ensure things work by adding any required alignment padding before
     171             :  * the "aset" field.  There is a static assertion below that the alignment
     172             :  * is done correctly.
     173             :  */
     174             : typedef struct AllocChunkData
     175             : {
     176             :     /* size is always the size of the usable space in the chunk */
     177             :     Size        size;
     178             : #ifdef MEMORY_CONTEXT_CHECKING
     179             :     /* when debugging memory usage, also store actual requested size */
     180             :     /* this is zero in a free chunk */
     181             :     Size        requested_size;
     182             : 
     183             : #define ALLOCCHUNK_RAWSIZE  (SIZEOF_SIZE_T * 2 + SIZEOF_VOID_P)
     184             : #else
     185             : #define ALLOCCHUNK_RAWSIZE  (SIZEOF_SIZE_T + SIZEOF_VOID_P)
     186             : #endif                          /* MEMORY_CONTEXT_CHECKING */
     187             : 
     188             :     /* ensure proper alignment by adding padding if needed */
     189             : #if (ALLOCCHUNK_RAWSIZE % MAXIMUM_ALIGNOF) != 0
     190             :     char        padding[MAXIMUM_ALIGNOF - ALLOCCHUNK_RAWSIZE % MAXIMUM_ALIGNOF];
     191             : #endif
     192             : 
     193             :     /* aset is the owning aset if allocated, or the freelist link if free */
     194             :     void       *aset;
     195             :     /* there must not be any padding to reach a MAXALIGN boundary here! */
     196             : }           AllocChunkData;
     197             : 
     198             : /*
     199             :  * Only the "aset" field should be accessed outside this module.
     200             :  * We keep the rest of an allocated chunk's header marked NOACCESS when using
     201             :  * valgrind.  But note that chunk headers that are in a freelist are kept
     202             :  * accessible, for simplicity.
     203             :  */
     204             : #define ALLOCCHUNK_PRIVATE_LEN  offsetof(AllocChunkData, aset)
     205             : 
     206             : /*
     207             :  * AllocPointerIsValid
     208             :  *      True iff pointer is valid allocation pointer.
     209             :  */
     210             : #define AllocPointerIsValid(pointer) PointerIsValid(pointer)
     211             : 
     212             : /*
     213             :  * AllocSetIsValid
     214             :  *      True iff set is valid allocation set.
     215             :  */
     216             : #define AllocSetIsValid(set) PointerIsValid(set)
     217             : 
     218             : #define AllocPointerGetChunk(ptr)   \
     219             :                     ((AllocChunk)(((char *)(ptr)) - ALLOC_CHUNKHDRSZ))
     220             : #define AllocChunkGetPointer(chk)   \
     221             :                     ((AllocPointer)(((char *)(chk)) + ALLOC_CHUNKHDRSZ))
     222             : 
     223             : /*
     224             :  * Rather than repeatedly creating and deleting memory contexts, we keep some
     225             :  * freed contexts in freelists so that we can hand them out again with little
     226             :  * work.  Before putting a context in a freelist, we reset it so that it has
     227             :  * only its initial malloc chunk and no others.  To be a candidate for a
     228             :  * freelist, a context must have the same minContextSize/initBlockSize as
     229             :  * other contexts in the list; but its maxBlockSize is irrelevant since that
     230             :  * doesn't affect the size of the initial chunk.
     231             :  *
     232             :  * We currently provide one freelist for ALLOCSET_DEFAULT_SIZES contexts
     233             :  * and one for ALLOCSET_SMALL_SIZES contexts; the latter works for
     234             :  * ALLOCSET_START_SMALL_SIZES too, since only the maxBlockSize differs.
     235             :  *
     236             :  * Ordinarily, we re-use freelist contexts in last-in-first-out order, in
     237             :  * hopes of improving locality of reference.  But if there get to be too
     238             :  * many contexts in the list, we'd prefer to drop the most-recently-created
     239             :  * contexts in hopes of keeping the process memory map compact.
     240             :  * We approximate that by simply deleting all existing entries when the list
     241             :  * overflows, on the assumption that queries that allocate a lot of contexts
     242             :  * will probably free them in more or less reverse order of allocation.
     243             :  *
     244             :  * Contexts in a freelist are chained via their nextchild pointers.
     245             :  */
     246             : #define MAX_FREE_CONTEXTS 100   /* arbitrary limit on freelist length */
     247             : 
     248             : typedef struct AllocSetFreeList
     249             : {
     250             :     int         num_free;       /* current list length */
     251             :     AllocSetContext *first_free;    /* list header */
     252             : } AllocSetFreeList;
     253             : 
     254             : /* context_freelists[0] is for default params, [1] for small params */
     255             : static AllocSetFreeList context_freelists[2] =
     256             : {
     257             :     {
     258             :         0, NULL
     259             :     },
     260             :     {
     261             :         0, NULL
     262             :     }
     263             : };
     264             : 
     265             : /*
     266             :  * These functions implement the MemoryContext API for AllocSet contexts.
     267             :  */
     268             : static void *AllocSetAlloc(MemoryContext context, Size size);
     269             : static void AllocSetFree(MemoryContext context, void *pointer);
     270             : static void *AllocSetRealloc(MemoryContext context, void *pointer, Size size);
     271             : static void AllocSetReset(MemoryContext context);
     272             : static void AllocSetDelete(MemoryContext context);
     273             : static Size AllocSetGetChunkSpace(MemoryContext context, void *pointer);
     274             : static bool AllocSetIsEmpty(MemoryContext context);
     275             : static void AllocSetStats(MemoryContext context,
     276             :                           MemoryStatsPrintFunc printfunc, void *passthru,
     277             :                           MemoryContextCounters *totals);
     278             : 
     279             : #ifdef MEMORY_CONTEXT_CHECKING
     280             : static void AllocSetCheck(MemoryContext context);
     281             : #endif
     282             : 
     283             : /*
     284             :  * This is the virtual function table for AllocSet contexts.
     285             :  */
     286             : static const MemoryContextMethods AllocSetMethods = {
     287             :     AllocSetAlloc,
     288             :     AllocSetFree,
     289             :     AllocSetRealloc,
     290             :     AllocSetReset,
     291             :     AllocSetDelete,
     292             :     AllocSetGetChunkSpace,
     293             :     AllocSetIsEmpty,
     294             :     AllocSetStats
     295             : #ifdef MEMORY_CONTEXT_CHECKING
     296             :     ,AllocSetCheck
     297             : #endif
     298             : };
     299             : 
     300             : /*
     301             :  * Table for AllocSetFreeIndex
     302             :  */
     303             : #define LT16(n) n, n, n, n, n, n, n, n, n, n, n, n, n, n, n, n
     304             : 
     305             : static const unsigned char LogTable256[256] =
     306             : {
     307             :     0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
     308             :     LT16(5), LT16(6), LT16(6), LT16(7), LT16(7), LT16(7), LT16(7),
     309             :     LT16(8), LT16(8), LT16(8), LT16(8), LT16(8), LT16(8), LT16(8), LT16(8)
     310             : };
     311             : 
     312             : /* ----------
     313             :  * Debug macros
     314             :  * ----------
     315             :  */
     316             : #ifdef HAVE_ALLOCINFO
     317             : #define AllocFreeInfo(_cxt, _chunk) \
     318             :             fprintf(stderr, "AllocFree: %s: %p, %zu\n", \
     319             :                 (_cxt)->header.name, (_chunk), (_chunk)->size)
     320             : #define AllocAllocInfo(_cxt, _chunk) \
     321             :             fprintf(stderr, "AllocAlloc: %s: %p, %zu\n", \
     322             :                 (_cxt)->header.name, (_chunk), (_chunk)->size)
     323             : #else
     324             : #define AllocFreeInfo(_cxt, _chunk)
     325             : #define AllocAllocInfo(_cxt, _chunk)
     326             : #endif
     327             : 
     328             : /* ----------
     329             :  * AllocSetFreeIndex -
     330             :  *
     331             :  *      Depending on the size of an allocation compute which freechunk
     332             :  *      list of the alloc set it belongs to.  Caller must have verified
     333             :  *      that size <= ALLOC_CHUNK_LIMIT.
     334             :  * ----------
     335             :  */
     336             : static inline int
     337  1128512020 : AllocSetFreeIndex(Size size)
     338             : {
     339             :     int         idx;
     340             :     unsigned int t,
     341             :                 tsize;
     342             : 
     343  1128512020 :     if (size > (1 << ALLOC_MINBITS))
     344             :     {
     345  1022386668 :         tsize = (size - 1) >> ALLOC_MINBITS;
     346             : 
     347             :         /*
     348             :          * At this point we need to obtain log2(tsize)+1, ie, the number of
     349             :          * not-all-zero bits at the right.  We used to do this with a
     350             :          * shift-and-count loop, but this function is enough of a hotspot to
     351             :          * justify micro-optimization effort.  The best approach seems to be
     352             :          * to use a lookup table.  Note that this code assumes that
     353             :          * ALLOCSET_NUM_FREELISTS <= 17, since we only cope with two bytes of
     354             :          * the tsize value.
     355             :          */
     356  1022386668 :         t = tsize >> 8;
     357  1022386668 :         idx = t ? LogTable256[t] + 8 : LogTable256[tsize];
     358             : 
     359             :         Assert(idx < ALLOCSET_NUM_FREELISTS);
     360             :     }
     361             :     else
     362   106125352 :         idx = 0;
     363             : 
     364  1128512020 :     return idx;
     365             : }
     366             : 
     367             : 
     368             : /*
     369             :  * Public routines
     370             :  */
     371             : 
     372             : 
     373             : /*
     374             :  * AllocSetContextCreateInternal
     375             :  *      Create a new AllocSet context.
     376             :  *
     377             :  * parent: parent context, or NULL if top-level context
     378             :  * name: name of context (must be statically allocated)
     379             :  * minContextSize: minimum context size
     380             :  * initBlockSize: initial allocation block size
     381             :  * maxBlockSize: maximum allocation block size
     382             :  *
     383             :  * Most callers should abstract the context size parameters using a macro
     384             :  * such as ALLOCSET_DEFAULT_SIZES.
     385             :  *
     386             :  * Note: don't call this directly; go through the wrapper macro
     387             :  * AllocSetContextCreate.
     388             :  */
     389             : MemoryContext
     390     9940046 : AllocSetContextCreateInternal(MemoryContext parent,
     391             :                               const char *name,
     392             :                               Size minContextSize,
     393             :                               Size initBlockSize,
     394             :                               Size maxBlockSize)
     395             : {
     396             :     int         freeListIndex;
     397             :     Size        firstBlockSize;
     398             :     AllocSet    set;
     399             :     AllocBlock  block;
     400             : 
     401             :     /* Assert we padded AllocChunkData properly */
     402             :     StaticAssertStmt(ALLOC_CHUNKHDRSZ == MAXALIGN(ALLOC_CHUNKHDRSZ),
     403             :                      "sizeof(AllocChunkData) is not maxaligned");
     404             :     StaticAssertStmt(offsetof(AllocChunkData, aset) + sizeof(MemoryContext) ==
     405             :                      ALLOC_CHUNKHDRSZ,
     406             :                      "padding calculation in AllocChunkData is wrong");
     407             : 
     408             :     /*
     409             :      * First, validate allocation parameters.  Once these were regular runtime
     410             :      * test and elog's, but in practice Asserts seem sufficient because nobody
     411             :      * varies their parameters at runtime.  We somewhat arbitrarily enforce a
     412             :      * minimum 1K block size.
     413             :      */
     414             :     Assert(initBlockSize == MAXALIGN(initBlockSize) &&
     415             :            initBlockSize >= 1024);
     416             :     Assert(maxBlockSize == MAXALIGN(maxBlockSize) &&
     417             :            maxBlockSize >= initBlockSize &&
     418             :            AllocHugeSizeIsValid(maxBlockSize)); /* must be safe to double */
     419             :     Assert(minContextSize == 0 ||
     420             :            (minContextSize == MAXALIGN(minContextSize) &&
     421             :             minContextSize >= 1024 &&
     422             :             minContextSize <= maxBlockSize));
     423             : 
     424             :     /*
     425             :      * Check whether the parameters match either available freelist.  We do
     426             :      * not need to demand a match of maxBlockSize.
     427             :      */
     428     9940046 :     if (minContextSize == ALLOCSET_DEFAULT_MINSIZE &&
     429             :         initBlockSize == ALLOCSET_DEFAULT_INITSIZE)
     430     6916530 :         freeListIndex = 0;
     431     3023516 :     else if (minContextSize == ALLOCSET_SMALL_MINSIZE &&
     432             :              initBlockSize == ALLOCSET_SMALL_INITSIZE)
     433     3011072 :         freeListIndex = 1;
     434             :     else
     435       12444 :         freeListIndex = -1;
     436             : 
     437             :     /*
     438             :      * If a suitable freelist entry exists, just recycle that context.
     439             :      */
     440     9940046 :     if (freeListIndex >= 0)
     441             :     {
     442     9927602 :         AllocSetFreeList *freelist = &context_freelists[freeListIndex];
     443             : 
     444     9927602 :         if (freelist->first_free != NULL)
     445             :         {
     446             :             /* Remove entry from freelist */
     447     8812862 :             set = freelist->first_free;
     448     8812862 :             freelist->first_free = (AllocSet) set->header.nextchild;
     449     8812862 :             freelist->num_free--;
     450             : 
     451             :             /* Update its maxBlockSize; everything else should be OK */
     452     8812862 :             set->maxBlockSize = maxBlockSize;
     453             : 
     454             :             /* Reinitialize its header, installing correct name and parent */
     455     8812862 :             MemoryContextCreate((MemoryContext) set,
     456             :                                 T_AllocSetContext,
     457             :                                 &AllocSetMethods,
     458             :                                 parent,
     459             :                                 name);
     460             : 
     461     8812862 :             return (MemoryContext) set;
     462             :         }
     463             :     }
     464             : 
     465             :     /* Determine size of initial block */
     466     1127184 :     firstBlockSize = MAXALIGN(sizeof(AllocSetContext)) +
     467             :         ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ;
     468     1127184 :     if (minContextSize != 0)
     469       12444 :         firstBlockSize = Max(firstBlockSize, minContextSize);
     470             :     else
     471     1114740 :         firstBlockSize = Max(firstBlockSize, initBlockSize);
     472             : 
     473             :     /*
     474             :      * Allocate the initial block.  Unlike other aset.c blocks, it starts with
     475             :      * the context header and its block header follows that.
     476             :      */
     477     1127184 :     set = (AllocSet) malloc(firstBlockSize);
     478     1127184 :     if (set == NULL)
     479             :     {
     480           0 :         if (TopMemoryContext)
     481           0 :             MemoryContextStats(TopMemoryContext);
     482           0 :         ereport(ERROR,
     483             :                 (errcode(ERRCODE_OUT_OF_MEMORY),
     484             :                  errmsg("out of memory"),
     485             :                  errdetail("Failed while creating memory context \"%s\".",
     486             :                            name)));
     487             :     }
     488             : 
     489             :     /*
     490             :      * Avoid writing code that can fail between here and MemoryContextCreate;
     491             :      * we'd leak the header/initial block if we ereport in this stretch.
     492             :      */
     493             : 
     494             :     /* Fill in the initial block's block header */
     495     1127184 :     block = (AllocBlock) (((char *) set) + MAXALIGN(sizeof(AllocSetContext)));
     496     1127184 :     block->aset = set;
     497     1127184 :     block->freeptr = ((char *) block) + ALLOC_BLOCKHDRSZ;
     498     1127184 :     block->endptr = ((char *) set) + firstBlockSize;
     499     1127184 :     block->prev = NULL;
     500     1127184 :     block->next = NULL;
     501             : 
     502             :     /* Mark unallocated space NOACCESS; leave the block header alone. */
     503             :     VALGRIND_MAKE_MEM_NOACCESS(block->freeptr, block->endptr - block->freeptr);
     504             : 
     505             :     /* Remember block as part of block list */
     506     1127184 :     set->blocks = block;
     507             :     /* Mark block as not to be released at reset time */
     508     1127184 :     set->keeper = block;
     509             : 
     510             :     /* Finish filling in aset-specific parts of the context header */
     511     1127184 :     MemSetAligned(set->freelist, 0, sizeof(set->freelist));
     512             : 
     513     1127184 :     set->initBlockSize = initBlockSize;
     514     1127184 :     set->maxBlockSize = maxBlockSize;
     515     1127184 :     set->nextBlockSize = initBlockSize;
     516     1127184 :     set->freeListIndex = freeListIndex;
     517             : 
     518             :     /*
     519             :      * Compute the allocation chunk size limit for this context.  It can't be
     520             :      * more than ALLOC_CHUNK_LIMIT because of the fixed number of freelists.
     521             :      * If maxBlockSize is small then requests exceeding the maxBlockSize, or
     522             :      * even a significant fraction of it, should be treated as large chunks
     523             :      * too.  For the typical case of maxBlockSize a power of 2, the chunk size
     524             :      * limit will be at most 1/8th maxBlockSize, so that given a stream of
     525             :      * requests that are all the maximum chunk size we will waste at most
     526             :      * 1/8th of the allocated space.
     527             :      *
     528             :      * We have to have allocChunkLimit a power of two, because the requested
     529             :      * and actually-allocated sizes of any chunk must be on the same side of
     530             :      * the limit, else we get confused about whether the chunk is "big".
     531             :      *
     532             :      * Also, allocChunkLimit must not exceed ALLOCSET_SEPARATE_THRESHOLD.
     533             :      */
     534             :     StaticAssertStmt(ALLOC_CHUNK_LIMIT == ALLOCSET_SEPARATE_THRESHOLD,
     535             :                      "ALLOC_CHUNK_LIMIT != ALLOCSET_SEPARATE_THRESHOLD");
     536             : 
     537     1127184 :     set->allocChunkLimit = ALLOC_CHUNK_LIMIT;
     538     8326892 :     while ((Size) (set->allocChunkLimit + ALLOC_CHUNKHDRSZ) >
     539     3599854 :            (Size) ((maxBlockSize - ALLOC_BLOCKHDRSZ) / ALLOC_CHUNK_FRACTION))
     540     2472670 :         set->allocChunkLimit >>= 1;
     541             : 
     542             :     /* Finally, do the type-independent part of context creation */
     543     1127184 :     MemoryContextCreate((MemoryContext) set,
     544             :                         T_AllocSetContext,
     545             :                         &AllocSetMethods,
     546             :                         parent,
     547             :                         name);
     548             : 
     549     1127184 :     return (MemoryContext) set;
     550             : }
     551             : 
     552             : /*
     553             :  * AllocSetReset
     554             :  *      Frees all memory which is allocated in the given set.
     555             :  *
     556             :  * Actually, this routine has some discretion about what to do.
     557             :  * It should mark all allocated chunks freed, but it need not necessarily
     558             :  * give back all the resources the set owns.  Our actual implementation is
     559             :  * that we give back all but the "keeper" block (which we must keep, since
     560             :  * it shares a malloc chunk with the context header).  In this way, we don't
     561             :  * thrash malloc() when a context is repeatedly reset after small allocations,
     562             :  * which is typical behavior for per-tuple contexts.
     563             :  */
     564             : static void
     565    25041384 : AllocSetReset(MemoryContext context)
     566             : {
     567    25041384 :     AllocSet    set = (AllocSet) context;
     568             :     AllocBlock  block;
     569             : 
     570             :     AssertArg(AllocSetIsValid(set));
     571             : 
     572             : #ifdef MEMORY_CONTEXT_CHECKING
     573             :     /* Check for corruption and leaks before freeing */
     574             :     AllocSetCheck(context);
     575             : #endif
     576             : 
     577             :     /* Clear chunk freelists */
     578    25041384 :     MemSetAligned(set->freelist, 0, sizeof(set->freelist));
     579             : 
     580    25041384 :     block = set->blocks;
     581             : 
     582             :     /* New blocks list will be just the keeper block */
     583    25041384 :     set->blocks = set->keeper;
     584             : 
     585    81135498 :     while (block != NULL)
     586             :     {
     587    31052730 :         AllocBlock  next = block->next;
     588             : 
     589    31052730 :         if (block == set->keeper)
     590             :         {
     591             :             /* Reset the block, but don't return it to malloc */
     592    25041384 :             char       *datastart = ((char *) block) + ALLOC_BLOCKHDRSZ;
     593             : 
     594             : #ifdef CLOBBER_FREED_MEMORY
     595             :             wipe_mem(datastart, block->freeptr - datastart);
     596             : #else
     597             :             /* wipe_mem() would have done this */
     598             :             VALGRIND_MAKE_MEM_NOACCESS(datastart, block->freeptr - datastart);
     599             : #endif
     600    25041384 :             block->freeptr = datastart;
     601    25041384 :             block->prev = NULL;
     602    25041384 :             block->next = NULL;
     603             :         }
     604             :         else
     605             :         {
     606             :             /* Normal case, release the block */
     607             : #ifdef CLOBBER_FREED_MEMORY
     608             :             wipe_mem(block, block->freeptr - ((char *) block));
     609             : #endif
     610     6011346 :             free(block);
     611             :         }
     612    31052730 :         block = next;
     613             :     }
     614             : 
     615             :     /* Reset block size allocation sequence, too */
     616    25041384 :     set->nextBlockSize = set->initBlockSize;
     617    25041384 : }
     618             : 
     619             : /*
     620             :  * AllocSetDelete
     621             :  *      Frees all memory which is allocated in the given set,
     622             :  *      in preparation for deletion of the set.
     623             :  *
     624             :  * Unlike AllocSetReset, this *must* free all resources of the set.
     625             :  */
     626             : static void
     627     9053960 : AllocSetDelete(MemoryContext context)
     628             : {
     629     9053960 :     AllocSet    set = (AllocSet) context;
     630     9053960 :     AllocBlock  block = set->blocks;
     631             : 
     632             :     AssertArg(AllocSetIsValid(set));
     633             : 
     634             : #ifdef MEMORY_CONTEXT_CHECKING
     635             :     /* Check for corruption and leaks before freeing */
     636             :     AllocSetCheck(context);
     637             : #endif
     638             : 
     639             :     /*
     640             :      * If the context is a candidate for a freelist, put it into that freelist
     641             :      * instead of destroying it.
     642             :      */
     643     9053960 :     if (set->freeListIndex >= 0)
     644             :     {
     645     9053960 :         AllocSetFreeList *freelist = &context_freelists[set->freeListIndex];
     646             : 
     647             :         /*
     648             :          * Reset the context, if it needs it, so that we aren't hanging on to
     649             :          * more than the initial malloc chunk.
     650             :          */
     651     9053960 :         if (!context->isReset)
     652     6282528 :             MemoryContextResetOnly(context);
     653             : 
     654             :         /*
     655             :          * If the freelist is full, just discard what's already in it.  See
     656             :          * comments with context_freelists[].
     657             :          */
     658     9053960 :         if (freelist->num_free >= MAX_FREE_CONTEXTS)
     659             :         {
     660       30396 :             while (freelist->first_free != NULL)
     661             :             {
     662       29800 :                 AllocSetContext *oldset = freelist->first_free;
     663             : 
     664       29800 :                 freelist->first_free = (AllocSetContext *) oldset->header.nextchild;
     665       29800 :                 freelist->num_free--;
     666             : 
     667             :                 /* All that remains is to free the header/initial block */
     668       29800 :                 free(oldset);
     669             :             }
     670             :             Assert(freelist->num_free == 0);
     671             :         }
     672             : 
     673             :         /* Now add the just-deleted context to the freelist. */
     674     9053960 :         set->header.nextchild = (MemoryContext) freelist->first_free;
     675     9053960 :         freelist->first_free = set;
     676     9053960 :         freelist->num_free++;
     677             : 
     678     9053960 :         return;
     679             :     }
     680             : 
     681             :     /* Free all blocks, except the keeper which is part of context header */
     682           0 :     while (block != NULL)
     683             :     {
     684           0 :         AllocBlock  next = block->next;
     685             : 
     686             : #ifdef CLOBBER_FREED_MEMORY
     687             :         wipe_mem(block, block->freeptr - ((char *) block));
     688             : #endif
     689             : 
     690           0 :         if (block != set->keeper)
     691           0 :             free(block);
     692             : 
     693           0 :         block = next;
     694             :     }
     695             : 
     696             :     /* Finally, free the context header, including the keeper block */
     697           0 :     free(set);
     698             : }
     699             : 
     700             : /*
     701             :  * AllocSetAlloc
     702             :  *      Returns pointer to allocated memory of given size or NULL if
     703             :  *      request could not be completed; memory is added to the set.
     704             :  *
     705             :  * No request may exceed:
     706             :  *      MAXALIGN_DOWN(SIZE_MAX) - ALLOC_BLOCKHDRSZ - ALLOC_CHUNKHDRSZ
     707             :  * All callers use a much-lower limit.
     708             :  *
     709             :  * Note: when using valgrind, it doesn't matter how the returned allocation
     710             :  * is marked, as mcxt.c will set it to UNDEFINED.  In some paths we will
     711             :  * return space that is marked NOACCESS - AllocSetRealloc has to beware!
     712             :  */
     713             : static void *
     714   855269894 : AllocSetAlloc(MemoryContext context, Size size)
     715             : {
     716   855269894 :     AllocSet    set = (AllocSet) context;
     717             :     AllocBlock  block;
     718             :     AllocChunk  chunk;
     719             :     int         fidx;
     720             :     Size        chunk_size;
     721             :     Size        blksize;
     722             : 
     723             :     AssertArg(AllocSetIsValid(set));
     724             : 
     725             :     /*
     726             :      * If requested size exceeds maximum for chunks, allocate an entire block
     727             :      * for this request.
     728             :      */
     729   855269894 :     if (size > set->allocChunkLimit)
     730             :     {
     731    14888054 :         chunk_size = MAXALIGN(size);
     732    14888054 :         blksize = chunk_size + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ;
     733    14888054 :         block = (AllocBlock) malloc(blksize);
     734    14888054 :         if (block == NULL)
     735           0 :             return NULL;
     736    14888054 :         block->aset = set;
     737    14888054 :         block->freeptr = block->endptr = ((char *) block) + blksize;
     738             : 
     739    14888054 :         chunk = (AllocChunk) (((char *) block) + ALLOC_BLOCKHDRSZ);
     740    14888054 :         chunk->aset = set;
     741    14888054 :         chunk->size = chunk_size;
     742             : #ifdef MEMORY_CONTEXT_CHECKING
     743             :         chunk->requested_size = size;
     744             :         /* set mark to catch clobber of "unused" space */
     745             :         if (size < chunk_size)
     746             :             set_sentinel(AllocChunkGetPointer(chunk), size);
     747             : #endif
     748             : #ifdef RANDOMIZE_ALLOCATED_MEMORY
     749             :         /* fill the allocated space with junk */
     750             :         randomize_mem((char *) AllocChunkGetPointer(chunk), size);
     751             : #endif
     752             : 
     753             :         /*
     754             :          * Stick the new block underneath the active allocation block, if any,
     755             :          * so that we don't lose the use of the space remaining therein.
     756             :          */
     757    14888054 :         if (set->blocks != NULL)
     758             :         {
     759    14888054 :             block->prev = set->blocks;
     760    14888054 :             block->next = set->blocks->next;
     761    14888054 :             if (block->next)
     762    12028132 :                 block->next->prev = block;
     763    14888054 :             set->blocks->next = block;
     764             :         }
     765             :         else
     766             :         {
     767           0 :             block->prev = NULL;
     768           0 :             block->next = NULL;
     769           0 :             set->blocks = block;
     770             :         }
     771             : 
     772             :         AllocAllocInfo(set, chunk);
     773             : 
     774             :         /* Ensure any padding bytes are marked NOACCESS. */
     775             :         VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
     776             :                                    chunk_size - size);
     777             : 
     778             :         /* Disallow external access to private part of chunk header. */
     779             :         VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
     780             : 
     781    14888054 :         return AllocChunkGetPointer(chunk);
     782             :     }
     783             : 
     784             :     /*
     785             :      * Request is small enough to be treated as a chunk.  Look in the
     786             :      * corresponding free list to see if there is a free chunk we could reuse.
     787             :      * If one is found, remove it from the free list, make it again a member
     788             :      * of the alloc set and return its data address.
     789             :      */
     790   840381840 :     fidx = AllocSetFreeIndex(size);
     791   840381840 :     chunk = set->freelist[fidx];
     792   840381840 :     if (chunk != NULL)
     793             :     {
     794             :         Assert(chunk->size >= size);
     795             : 
     796   250712664 :         set->freelist[fidx] = (AllocChunk) chunk->aset;
     797             : 
     798   250712664 :         chunk->aset = (void *) set;
     799             : 
     800             : #ifdef MEMORY_CONTEXT_CHECKING
     801             :         chunk->requested_size = size;
     802             :         /* set mark to catch clobber of "unused" space */
     803             :         if (size < chunk->size)
     804             :             set_sentinel(AllocChunkGetPointer(chunk), size);
     805             : #endif
     806             : #ifdef RANDOMIZE_ALLOCATED_MEMORY
     807             :         /* fill the allocated space with junk */
     808             :         randomize_mem((char *) AllocChunkGetPointer(chunk), size);
     809             : #endif
     810             : 
     811             :         AllocAllocInfo(set, chunk);
     812             : 
     813             :         /* Ensure any padding bytes are marked NOACCESS. */
     814             :         VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
     815             :                                    chunk->size - size);
     816             : 
     817             :         /* Disallow external access to private part of chunk header. */
     818             :         VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
     819             : 
     820   250712664 :         return AllocChunkGetPointer(chunk);
     821             :     }
     822             : 
     823             :     /*
     824             :      * Choose the actual chunk size to allocate.
     825             :      */
     826   589669176 :     chunk_size = (1 << ALLOC_MINBITS) << fidx;
     827             :     Assert(chunk_size >= size);
     828             : 
     829             :     /*
     830             :      * If there is enough room in the active allocation block, we will put the
     831             :      * chunk into that block.  Else must start a new one.
     832             :      */
     833   589669176 :     if ((block = set->blocks) != NULL)
     834             :     {
     835   589669176 :         Size        availspace = block->endptr - block->freeptr;
     836             : 
     837   589669176 :         if (availspace < (chunk_size + ALLOC_CHUNKHDRSZ))
     838             :         {
     839             :             /*
     840             :              * The existing active (top) block does not have enough room for
     841             :              * the requested allocation, but it might still have a useful
     842             :              * amount of space in it.  Once we push it down in the block list,
     843             :              * we'll never try to allocate more space from it. So, before we
     844             :              * do that, carve up its free space into chunks that we can put on
     845             :              * the set's freelists.
     846             :              *
     847             :              * Because we can only get here when there's less than
     848             :              * ALLOC_CHUNK_LIMIT left in the block, this loop cannot iterate
     849             :              * more than ALLOCSET_NUM_FREELISTS-1 times.
     850             :              */
     851    16519776 :             while (availspace >= ((1 << ALLOC_MINBITS) + ALLOC_CHUNKHDRSZ))
     852             :             {
     853     7905652 :                 Size        availchunk = availspace - ALLOC_CHUNKHDRSZ;
     854     7905652 :                 int         a_fidx = AllocSetFreeIndex(availchunk);
     855             : 
     856             :                 /*
     857             :                  * In most cases, we'll get back the index of the next larger
     858             :                  * freelist than the one we need to put this chunk on.  The
     859             :                  * exception is when availchunk is exactly a power of 2.
     860             :                  */
     861     7905652 :                 if (availchunk != ((Size) 1 << (a_fidx + ALLOC_MINBITS)))
     862             :                 {
     863     5623708 :                     a_fidx--;
     864             :                     Assert(a_fidx >= 0);
     865     5623708 :                     availchunk = ((Size) 1 << (a_fidx + ALLOC_MINBITS));
     866             :                 }
     867             : 
     868     7905652 :                 chunk = (AllocChunk) (block->freeptr);
     869             : 
     870             :                 /* Prepare to initialize the chunk header. */
     871             :                 VALGRIND_MAKE_MEM_UNDEFINED(chunk, ALLOC_CHUNKHDRSZ);
     872             : 
     873     7905652 :                 block->freeptr += (availchunk + ALLOC_CHUNKHDRSZ);
     874     7905652 :                 availspace -= (availchunk + ALLOC_CHUNKHDRSZ);
     875             : 
     876     7905652 :                 chunk->size = availchunk;
     877             : #ifdef MEMORY_CONTEXT_CHECKING
     878             :                 chunk->requested_size = 0;   /* mark it free */
     879             : #endif
     880     7905652 :                 chunk->aset = (void *) set->freelist[a_fidx];
     881     7905652 :                 set->freelist[a_fidx] = chunk;
     882             :             }
     883             : 
     884             :             /* Mark that we need to create a new block */
     885     4307062 :             block = NULL;
     886             :         }
     887             :     }
     888             : 
     889             :     /*
     890             :      * Time to create a new regular (multi-chunk) block?
     891             :      */
     892   589669176 :     if (block == NULL)
     893             :     {
     894             :         Size        required_size;
     895             : 
     896             :         /*
     897             :          * The first such block has size initBlockSize, and we double the
     898             :          * space in each succeeding block, but not more than maxBlockSize.
     899             :          */
     900     4307062 :         blksize = set->nextBlockSize;
     901     4307062 :         set->nextBlockSize <<= 1;
     902     4307062 :         if (set->nextBlockSize > set->maxBlockSize)
     903      872898 :             set->nextBlockSize = set->maxBlockSize;
     904             : 
     905             :         /*
     906             :          * If initBlockSize is less than ALLOC_CHUNK_LIMIT, we could need more
     907             :          * space... but try to keep it a power of 2.
     908             :          */
     909     4307062 :         required_size = chunk_size + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ;
     910     9043516 :         while (blksize < required_size)
     911      429392 :             blksize <<= 1;
     912             : 
     913             :         /* Try to allocate it */
     914     4307062 :         block = (AllocBlock) malloc(blksize);
     915             : 
     916             :         /*
     917             :          * We could be asking for pretty big blocks here, so cope if malloc
     918             :          * fails.  But give up if there's less than 1 MB or so available...
     919             :          */
     920     8614124 :         while (block == NULL && blksize > 1024 * 1024)
     921             :         {
     922           0 :             blksize >>= 1;
     923           0 :             if (blksize < required_size)
     924           0 :                 break;
     925           0 :             block = (AllocBlock) malloc(blksize);
     926             :         }
     927             : 
     928     4307062 :         if (block == NULL)
     929           0 :             return NULL;
     930             : 
     931     4307062 :         block->aset = set;
     932     4307062 :         block->freeptr = ((char *) block) + ALLOC_BLOCKHDRSZ;
     933     4307062 :         block->endptr = ((char *) block) + blksize;
     934             : 
     935             :         /* Mark unallocated space NOACCESS. */
     936             :         VALGRIND_MAKE_MEM_NOACCESS(block->freeptr,
     937             :                                    blksize - ALLOC_BLOCKHDRSZ);
     938             : 
     939     4307062 :         block->prev = NULL;
     940     4307062 :         block->next = set->blocks;
     941     4307062 :         if (block->next)
     942     4307062 :             block->next->prev = block;
     943     4307062 :         set->blocks = block;
     944             :     }
     945             : 
     946             :     /*
     947             :      * OK, do the allocation
     948             :      */
     949   589669176 :     chunk = (AllocChunk) (block->freeptr);
     950             : 
     951             :     /* Prepare to initialize the chunk header. */
     952             :     VALGRIND_MAKE_MEM_UNDEFINED(chunk, ALLOC_CHUNKHDRSZ);
     953             : 
     954   589669176 :     block->freeptr += (chunk_size + ALLOC_CHUNKHDRSZ);
     955             :     Assert(block->freeptr <= block->endptr);
     956             : 
     957   589669176 :     chunk->aset = (void *) set;
     958   589669176 :     chunk->size = chunk_size;
     959             : #ifdef MEMORY_CONTEXT_CHECKING
     960             :     chunk->requested_size = size;
     961             :     /* set mark to catch clobber of "unused" space */
     962             :     if (size < chunk->size)
     963             :         set_sentinel(AllocChunkGetPointer(chunk), size);
     964             : #endif
     965             : #ifdef RANDOMIZE_ALLOCATED_MEMORY
     966             :     /* fill the allocated space with junk */
     967             :     randomize_mem((char *) AllocChunkGetPointer(chunk), size);
     968             : #endif
     969             : 
     970             :     AllocAllocInfo(set, chunk);
     971             : 
     972             :     /* Ensure any padding bytes are marked NOACCESS. */
     973             :     VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
     974             :                                chunk_size - size);
     975             : 
     976             :     /* Disallow external access to private part of chunk header. */
     977             :     VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
     978             : 
     979   589669176 :     return AllocChunkGetPointer(chunk);
     980             : }
     981             : 
     982             : /*
     983             :  * AllocSetFree
     984             :  *      Frees allocated memory; memory is removed from the set.
     985             :  */
     986             : static void
     987   292749082 : AllocSetFree(MemoryContext context, void *pointer)
     988             : {
     989   292749082 :     AllocSet    set = (AllocSet) context;
     990   292749082 :     AllocChunk  chunk = AllocPointerGetChunk(pointer);
     991             : 
     992             :     /* Allow access to private part of chunk header. */
     993             :     VALGRIND_MAKE_MEM_DEFINED(chunk, ALLOCCHUNK_PRIVATE_LEN);
     994             : 
     995             :     AllocFreeInfo(set, chunk);
     996             : 
     997             : #ifdef MEMORY_CONTEXT_CHECKING
     998             :     /* Test for someone scribbling on unused space in chunk */
     999             :     if (chunk->requested_size < chunk->size)
    1000             :         if (!sentinel_ok(pointer, chunk->requested_size))
    1001             :             elog(WARNING, "detected write past chunk end in %s %p",
    1002             :                  set->header.name, chunk);
    1003             : #endif
    1004             : 
    1005   292749082 :     if (chunk->size > set->allocChunkLimit)
    1006             :     {
    1007             :         /*
    1008             :          * Big chunks are certain to have been allocated as single-chunk
    1009             :          * blocks.  Just unlink that block and return it to malloc().
    1010             :          */
    1011    12524554 :         AllocBlock  block = (AllocBlock) (((char *) chunk) - ALLOC_BLOCKHDRSZ);
    1012             : 
    1013             :         /*
    1014             :          * Try to verify that we have a sane block pointer: it should
    1015             :          * reference the correct aset, and freeptr and endptr should point
    1016             :          * just past the chunk.
    1017             :          */
    1018    25049108 :         if (block->aset != set ||
    1019    25049108 :             block->freeptr != block->endptr ||
    1020    25049108 :             block->freeptr != ((char *) block) +
    1021    12524554 :             (chunk->size + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ))
    1022           0 :             elog(ERROR, "could not find block containing chunk %p", chunk);
    1023             : 
    1024             :         /* OK, remove block from aset's list and free it */
    1025    12524554 :         if (block->prev)
    1026    12524554 :             block->prev->next = block->next;
    1027             :         else
    1028           0 :             set->blocks = block->next;
    1029    12524554 :         if (block->next)
    1030    11036924 :             block->next->prev = block->prev;
    1031             : #ifdef CLOBBER_FREED_MEMORY
    1032             :         wipe_mem(block, block->freeptr - ((char *) block));
    1033             : #endif
    1034    12524554 :         free(block);
    1035             :     }
    1036             :     else
    1037             :     {
    1038             :         /* Normal case, put the chunk into appropriate freelist */
    1039   280224528 :         int         fidx = AllocSetFreeIndex(chunk->size);
    1040             : 
    1041   280224528 :         chunk->aset = (void *) set->freelist[fidx];
    1042             : 
    1043             : #ifdef CLOBBER_FREED_MEMORY
    1044             :         wipe_mem(pointer, chunk->size);
    1045             : #endif
    1046             : 
    1047             : #ifdef MEMORY_CONTEXT_CHECKING
    1048             :         /* Reset requested_size to 0 in chunks that are on freelist */
    1049             :         chunk->requested_size = 0;
    1050             : #endif
    1051   280224528 :         set->freelist[fidx] = chunk;
    1052             :     }
    1053   292749082 : }
    1054             : 
    1055             : /*
    1056             :  * AllocSetRealloc
    1057             :  *      Returns new pointer to allocated memory of given size or NULL if
    1058             :  *      request could not be completed; this memory is added to the set.
    1059             :  *      Memory associated with given pointer is copied into the new memory,
    1060             :  *      and the old memory is freed.
    1061             :  *
    1062             :  * Without MEMORY_CONTEXT_CHECKING, we don't know the old request size.  This
    1063             :  * makes our Valgrind client requests less-precise, hazarding false negatives.
    1064             :  * (In principle, we could use VALGRIND_GET_VBITS() to rediscover the old
    1065             :  * request size.)
    1066             :  */
    1067             : static void *
    1068     7450566 : AllocSetRealloc(MemoryContext context, void *pointer, Size size)
    1069             : {
    1070     7450566 :     AllocSet    set = (AllocSet) context;
    1071     7450566 :     AllocChunk  chunk = AllocPointerGetChunk(pointer);
    1072             :     Size        oldsize;
    1073             : 
    1074             :     /* Allow access to private part of chunk header. */
    1075             :     VALGRIND_MAKE_MEM_DEFINED(chunk, ALLOCCHUNK_PRIVATE_LEN);
    1076             : 
    1077     7450566 :     oldsize = chunk->size;
    1078             : 
    1079             : #ifdef MEMORY_CONTEXT_CHECKING
    1080             :     /* Test for someone scribbling on unused space in chunk */
    1081             :     if (chunk->requested_size < oldsize)
    1082             :         if (!sentinel_ok(pointer, chunk->requested_size))
    1083             :             elog(WARNING, "detected write past chunk end in %s %p",
    1084             :                  set->header.name, chunk);
    1085             : #endif
    1086             : 
    1087             :     /*
    1088             :      * Chunk sizes are aligned to power of 2 in AllocSetAlloc(). Maybe the
    1089             :      * allocated area already is >= the new size.  (In particular, we always
    1090             :      * fall out here if the requested size is a decrease.)
    1091             :      */
    1092     7450566 :     if (oldsize >= size)
    1093             :     {
    1094             : #ifdef MEMORY_CONTEXT_CHECKING
    1095             :         Size        oldrequest = chunk->requested_size;
    1096             : 
    1097             : #ifdef RANDOMIZE_ALLOCATED_MEMORY
    1098             :         /* We can only fill the extra space if we know the prior request */
    1099             :         if (size > oldrequest)
    1100             :             randomize_mem((char *) pointer + oldrequest,
    1101             :                           size - oldrequest);
    1102             : #endif
    1103             : 
    1104             :         chunk->requested_size = size;
    1105             : 
    1106             :         /*
    1107             :          * If this is an increase, mark any newly-available part UNDEFINED.
    1108             :          * Otherwise, mark the obsolete part NOACCESS.
    1109             :          */
    1110             :         if (size > oldrequest)
    1111             :             VALGRIND_MAKE_MEM_UNDEFINED((char *) pointer + oldrequest,
    1112             :                                         size - oldrequest);
    1113             :         else
    1114             :             VALGRIND_MAKE_MEM_NOACCESS((char *) pointer + size,
    1115             :                                        oldsize - size);
    1116             : 
    1117             :         /* set mark to catch clobber of "unused" space */
    1118             :         if (size < oldsize)
    1119             :             set_sentinel(pointer, size);
    1120             : #else                           /* !MEMORY_CONTEXT_CHECKING */
    1121             : 
    1122             :         /*
    1123             :          * We don't have the information to determine whether we're growing
    1124             :          * the old request or shrinking it, so we conservatively mark the
    1125             :          * entire new allocation DEFINED.
    1126             :          */
    1127             :         VALGRIND_MAKE_MEM_NOACCESS(pointer, oldsize);
    1128             :         VALGRIND_MAKE_MEM_DEFINED(pointer, size);
    1129             : #endif
    1130             : 
    1131             :         /* Disallow external access to private part of chunk header. */
    1132             :         VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
    1133             : 
    1134     3864720 :         return pointer;
    1135             :     }
    1136             : 
    1137     3585846 :     if (oldsize > set->allocChunkLimit)
    1138             :     {
    1139             :         /*
    1140             :          * The chunk must have been allocated as a single-chunk block.  Use
    1141             :          * realloc() to make the containing block bigger with minimum space
    1142             :          * wastage.
    1143             :          */
    1144      211362 :         AllocBlock  block = (AllocBlock) (((char *) chunk) - ALLOC_BLOCKHDRSZ);
    1145             :         Size        chksize;
    1146             :         Size        blksize;
    1147             : 
    1148             :         /*
    1149             :          * Try to verify that we have a sane block pointer: it should
    1150             :          * reference the correct aset, and freeptr and endptr should point
    1151             :          * just past the chunk.
    1152             :          */
    1153      422724 :         if (block->aset != set ||
    1154      422724 :             block->freeptr != block->endptr ||
    1155      422724 :             block->freeptr != ((char *) block) +
    1156      211362 :             (chunk->size + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ))
    1157           0 :             elog(ERROR, "could not find block containing chunk %p", chunk);
    1158             : 
    1159             :         /* Do the realloc */
    1160      211362 :         chksize = MAXALIGN(size);
    1161      211362 :         blksize = chksize + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ;
    1162      211362 :         block = (AllocBlock) realloc(block, blksize);
    1163      211362 :         if (block == NULL)
    1164             :         {
    1165             :             /* Disallow external access to private part of chunk header. */
    1166             :             VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
    1167           0 :             return NULL;
    1168             :         }
    1169      211362 :         block->freeptr = block->endptr = ((char *) block) + blksize;
    1170             : 
    1171             :         /* Update pointers since block has likely been moved */
    1172      211362 :         chunk = (AllocChunk) (((char *) block) + ALLOC_BLOCKHDRSZ);
    1173      211362 :         pointer = AllocChunkGetPointer(chunk);
    1174      211362 :         if (block->prev)
    1175      211362 :             block->prev->next = block;
    1176             :         else
    1177           0 :             set->blocks = block;
    1178      211362 :         if (block->next)
    1179      197976 :             block->next->prev = block;
    1180      211362 :         chunk->size = chksize;
    1181             : 
    1182             : #ifdef MEMORY_CONTEXT_CHECKING
    1183             : #ifdef RANDOMIZE_ALLOCATED_MEMORY
    1184             :         /* We can only fill the extra space if we know the prior request */
    1185             :         randomize_mem((char *) pointer + chunk->requested_size,
    1186             :                       size - chunk->requested_size);
    1187             : #endif
    1188             : 
    1189             :         /*
    1190             :          * realloc() (or randomize_mem()) will have left the newly-allocated
    1191             :          * part UNDEFINED, but we may need to adjust trailing bytes from the
    1192             :          * old allocation.
    1193             :          */
    1194             :         VALGRIND_MAKE_MEM_UNDEFINED((char *) pointer + chunk->requested_size,
    1195             :                                     oldsize - chunk->requested_size);
    1196             : 
    1197             :         chunk->requested_size = size;
    1198             : 
    1199             :         /* set mark to catch clobber of "unused" space */
    1200             :         if (size < chunk->size)
    1201             :             set_sentinel(pointer, size);
    1202             : #else                           /* !MEMORY_CONTEXT_CHECKING */
    1203             : 
    1204             :         /*
    1205             :          * We don't know how much of the old chunk size was the actual
    1206             :          * allocation; it could have been as small as one byte.  We have to be
    1207             :          * conservative and just mark the entire old portion DEFINED.
    1208             :          */
    1209             :         VALGRIND_MAKE_MEM_DEFINED(pointer, oldsize);
    1210             : #endif
    1211             : 
    1212             :         /* Ensure any padding bytes are marked NOACCESS. */
    1213             :         VALGRIND_MAKE_MEM_NOACCESS((char *) pointer + size, chksize - size);
    1214             : 
    1215             :         /* Disallow external access to private part of chunk header. */
    1216             :         VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
    1217             : 
    1218      211362 :         return pointer;
    1219             :     }
    1220             :     else
    1221             :     {
    1222             :         /*
    1223             :          * Small-chunk case.  We just do this by brute force, ie, allocate a
    1224             :          * new chunk and copy the data.  Since we know the existing data isn't
    1225             :          * huge, this won't involve any great memcpy expense, so it's not
    1226             :          * worth being smarter.  (At one time we tried to avoid memcpy when it
    1227             :          * was possible to enlarge the chunk in-place, but that turns out to
    1228             :          * misbehave unpleasantly for repeated cycles of
    1229             :          * palloc/repalloc/pfree: the eventually freed chunks go into the
    1230             :          * wrong freelist for the next initial palloc request, and so we leak
    1231             :          * memory indefinitely.  See pgsql-hackers archives for 2007-08-11.)
    1232             :          */
    1233             :         AllocPointer newPointer;
    1234             : 
    1235             :         /* allocate new chunk */
    1236     3374484 :         newPointer = AllocSetAlloc((MemoryContext) set, size);
    1237             : 
    1238             :         /* leave immediately if request was not completed */
    1239     3374484 :         if (newPointer == NULL)
    1240             :         {
    1241             :             /* Disallow external access to private part of chunk header. */
    1242             :             VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
    1243           0 :             return NULL;
    1244             :         }
    1245             : 
    1246             :         /*
    1247             :          * AllocSetAlloc() may have returned a region that is still NOACCESS.
    1248             :          * Change it to UNDEFINED for the moment; memcpy() will then transfer
    1249             :          * definedness from the old allocation to the new.  If we know the old
    1250             :          * allocation, copy just that much.  Otherwise, make the entire old
    1251             :          * chunk defined to avoid errors as we copy the currently-NOACCESS
    1252             :          * trailing bytes.
    1253             :          */
    1254             :         VALGRIND_MAKE_MEM_UNDEFINED(newPointer, size);
    1255             : #ifdef MEMORY_CONTEXT_CHECKING
    1256             :         oldsize = chunk->requested_size;
    1257             : #else
    1258             :         VALGRIND_MAKE_MEM_DEFINED(pointer, oldsize);
    1259             : #endif
    1260             : 
    1261             :         /* transfer existing data (certain to fit) */
    1262     3374484 :         memcpy(newPointer, pointer, oldsize);
    1263             : 
    1264             :         /* free old chunk */
    1265     3374484 :         AllocSetFree((MemoryContext) set, pointer);
    1266             : 
    1267     3374484 :         return newPointer;
    1268             :     }
    1269             : }
    1270             : 
    1271             : /*
    1272             :  * AllocSetGetChunkSpace
    1273             :  *      Given a currently-allocated chunk, determine the total space
    1274             :  *      it occupies (including all memory-allocation overhead).
    1275             :  */
    1276             : static Size
    1277    58968730 : AllocSetGetChunkSpace(MemoryContext context, void *pointer)
    1278             : {
    1279    58968730 :     AllocChunk  chunk = AllocPointerGetChunk(pointer);
    1280             :     Size        result;
    1281             : 
    1282             :     VALGRIND_MAKE_MEM_DEFINED(chunk, ALLOCCHUNK_PRIVATE_LEN);
    1283    58968730 :     result = chunk->size + ALLOC_CHUNKHDRSZ;
    1284             :     VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
    1285    58968730 :     return result;
    1286             : }
    1287             : 
    1288             : /*
    1289             :  * AllocSetIsEmpty
    1290             :  *      Is an allocset empty of any allocated space?
    1291             :  */
    1292             : static bool
    1293        4436 : AllocSetIsEmpty(MemoryContext context)
    1294             : {
    1295             :     /*
    1296             :      * For now, we say "empty" only if the context is new or just reset. We
    1297             :      * could examine the freelists to determine if all space has been freed,
    1298             :      * but it's not really worth the trouble for present uses of this
    1299             :      * functionality.
    1300             :      */
    1301        4436 :     if (context->isReset)
    1302        4378 :         return true;
    1303          58 :     return false;
    1304             : }
    1305             : 
    1306             : /*
    1307             :  * AllocSetStats
    1308             :  *      Compute stats about memory consumption of an allocset.
    1309             :  *
    1310             :  * printfunc: if not NULL, pass a human-readable stats string to this.
    1311             :  * passthru: pass this pointer through to printfunc.
    1312             :  * totals: if not NULL, add stats about this context into *totals.
    1313             :  */
    1314             : static void
    1315           0 : AllocSetStats(MemoryContext context,
    1316             :               MemoryStatsPrintFunc printfunc, void *passthru,
    1317             :               MemoryContextCounters *totals)
    1318             : {
    1319           0 :     AllocSet    set = (AllocSet) context;
    1320           0 :     Size        nblocks = 0;
    1321           0 :     Size        freechunks = 0;
    1322             :     Size        totalspace;
    1323           0 :     Size        freespace = 0;
    1324             :     AllocBlock  block;
    1325             :     int         fidx;
    1326             : 
    1327             :     /* Include context header in totalspace */
    1328           0 :     totalspace = MAXALIGN(sizeof(AllocSetContext));
    1329             : 
    1330           0 :     for (block = set->blocks; block != NULL; block = block->next)
    1331             :     {
    1332           0 :         nblocks++;
    1333           0 :         totalspace += block->endptr - ((char *) block);
    1334           0 :         freespace += block->endptr - block->freeptr;
    1335             :     }
    1336           0 :     for (fidx = 0; fidx < ALLOCSET_NUM_FREELISTS; fidx++)
    1337             :     {
    1338             :         AllocChunk  chunk;
    1339             : 
    1340           0 :         for (chunk = set->freelist[fidx]; chunk != NULL;
    1341           0 :              chunk = (AllocChunk) chunk->aset)
    1342             :         {
    1343           0 :             freechunks++;
    1344           0 :             freespace += chunk->size + ALLOC_CHUNKHDRSZ;
    1345             :         }
    1346             :     }
    1347             : 
    1348           0 :     if (printfunc)
    1349             :     {
    1350             :         char        stats_string[200];
    1351             : 
    1352           0 :         snprintf(stats_string, sizeof(stats_string),
    1353             :                  "%zu total in %zd blocks; %zu free (%zd chunks); %zu used",
    1354             :                  totalspace, nblocks, freespace, freechunks,
    1355             :                  totalspace - freespace);
    1356           0 :         printfunc(context, passthru, stats_string);
    1357             :     }
    1358             : 
    1359           0 :     if (totals)
    1360             :     {
    1361           0 :         totals->nblocks += nblocks;
    1362           0 :         totals->freechunks += freechunks;
    1363           0 :         totals->totalspace += totalspace;
    1364           0 :         totals->freespace += freespace;
    1365             :     }
    1366           0 : }
    1367             : 
    1368             : 
    1369             : #ifdef MEMORY_CONTEXT_CHECKING
    1370             : 
    1371             : /*
    1372             :  * AllocSetCheck
    1373             :  *      Walk through chunks and check consistency of memory.
    1374             :  *
    1375             :  * NOTE: report errors as WARNING, *not* ERROR or FATAL.  Otherwise you'll
    1376             :  * find yourself in an infinite loop when trouble occurs, because this
    1377             :  * routine will be entered again when elog cleanup tries to release memory!
    1378             :  */
    1379             : static void
    1380             : AllocSetCheck(MemoryContext context)
    1381             : {
    1382             :     AllocSet    set = (AllocSet) context;
    1383             :     const char *name = set->header.name;
    1384             :     AllocBlock  prevblock;
    1385             :     AllocBlock  block;
    1386             : 
    1387             :     for (prevblock = NULL, block = set->blocks;
    1388             :          block != NULL;
    1389             :          prevblock = block, block = block->next)
    1390             :     {
    1391             :         char       *bpoz = ((char *) block) + ALLOC_BLOCKHDRSZ;
    1392             :         long        blk_used = block->freeptr - bpoz;
    1393             :         long        blk_data = 0;
    1394             :         long        nchunks = 0;
    1395             : 
    1396             :         /*
    1397             :          * Empty block - empty can be keeper-block only
    1398             :          */
    1399             :         if (!blk_used)
    1400             :         {
    1401             :             if (set->keeper != block)
    1402             :                 elog(WARNING, "problem in alloc set %s: empty block %p",
    1403             :                      name, block);
    1404             :         }
    1405             : 
    1406             :         /*
    1407             :          * Check block header fields
    1408             :          */
    1409             :         if (block->aset != set ||
    1410             :             block->prev != prevblock ||
    1411             :             block->freeptr < bpoz ||
    1412             :             block->freeptr > block->endptr)
    1413             :             elog(WARNING, "problem in alloc set %s: corrupt header in block %p",
    1414             :                  name, block);
    1415             : 
    1416             :         /*
    1417             :          * Chunk walker
    1418             :          */
    1419             :         while (bpoz < block->freeptr)
    1420             :         {
    1421             :             AllocChunk  chunk = (AllocChunk) bpoz;
    1422             :             Size        chsize,
    1423             :                         dsize;
    1424             : 
    1425             :             /* Allow access to private part of chunk header. */
    1426             :             VALGRIND_MAKE_MEM_DEFINED(chunk, ALLOCCHUNK_PRIVATE_LEN);
    1427             : 
    1428             :             chsize = chunk->size;    /* aligned chunk size */
    1429             :             dsize = chunk->requested_size;   /* real data */
    1430             : 
    1431             :             /*
    1432             :              * Check chunk size
    1433             :              */
    1434             :             if (dsize > chsize)
    1435             :                 elog(WARNING, "problem in alloc set %s: req size > alloc size for chunk %p in block %p",
    1436             :                      name, chunk, block);
    1437             :             if (chsize < (1 << ALLOC_MINBITS))
    1438             :                 elog(WARNING, "problem in alloc set %s: bad size %zu for chunk %p in block %p",
    1439             :                      name, chsize, chunk, block);
    1440             : 
    1441             :             /* single-chunk block? */
    1442             :             if (chsize > set->allocChunkLimit &&
    1443             :                 chsize + ALLOC_CHUNKHDRSZ != blk_used)
    1444             :                 elog(WARNING, "problem in alloc set %s: bad single-chunk %p in block %p",
    1445             :                      name, chunk, block);
    1446             : 
    1447             :             /*
    1448             :              * If chunk is allocated, check for correct aset pointer. (If it's
    1449             :              * free, the aset is the freelist pointer, which we can't check as
    1450             :              * easily...)  Note this is an incomplete test, since palloc(0)
    1451             :              * produces an allocated chunk with requested_size == 0.
    1452             :              */
    1453             :             if (dsize > 0 && chunk->aset != (void *) set)
    1454             :                 elog(WARNING, "problem in alloc set %s: bogus aset link in block %p, chunk %p",
    1455             :                      name, block, chunk);
    1456             : 
    1457             :             /*
    1458             :              * Check for overwrite of padding space in an allocated chunk.
    1459             :              */
    1460             :             if (chunk->aset == (void *) set && dsize < chsize &&
    1461             :                 !sentinel_ok(chunk, ALLOC_CHUNKHDRSZ + dsize))
    1462             :                 elog(WARNING, "problem in alloc set %s: detected write past chunk end in block %p, chunk %p",
    1463             :                      name, block, chunk);
    1464             : 
    1465             :             /*
    1466             :              * If chunk is allocated, disallow external access to private part
    1467             :              * of chunk header.
    1468             :              */
    1469             :             if (chunk->aset == (void *) set)
    1470             :                 VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
    1471             : 
    1472             :             blk_data += chsize;
    1473             :             nchunks++;
    1474             : 
    1475             :             bpoz += ALLOC_CHUNKHDRSZ + chsize;
    1476             :         }
    1477             : 
    1478             :         if ((blk_data + (nchunks * ALLOC_CHUNKHDRSZ)) != blk_used)
    1479             :             elog(WARNING, "problem in alloc set %s: found inconsistent memory block %p",
    1480             :                  name, block);
    1481             :     }
    1482             : }
    1483             : 
    1484             : #endif                          /* MEMORY_CONTEXT_CHECKING */

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