LCOV - code coverage report
Current view: top level - src/include/utils - palloc.h (source / functions) Hit Total Coverage
Test: PostgreSQL 12beta2 Lines: 4 4 100.0 %
Date: 2019-06-19 16:07:09 Functions: 1 1 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * palloc.h
       4             :  *    POSTGRES memory allocator definitions.
       5             :  *
       6             :  * This file contains the basic memory allocation interface that is
       7             :  * needed by almost every backend module.  It is included directly by
       8             :  * postgres.h, so the definitions here are automatically available
       9             :  * everywhere.  Keep it lean!
      10             :  *
      11             :  * Memory allocation occurs within "contexts".  Every chunk obtained from
      12             :  * palloc()/MemoryContextAlloc() is allocated within a specific context.
      13             :  * The entire contents of a context can be freed easily and quickly by
      14             :  * resetting or deleting the context --- this is both faster and less
      15             :  * prone to memory-leakage bugs than releasing chunks individually.
      16             :  * We organize contexts into context trees to allow fine-grain control
      17             :  * over chunk lifetime while preserving the certainty that we will free
      18             :  * everything that should be freed.  See utils/mmgr/README for more info.
      19             :  *
      20             :  *
      21             :  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
      22             :  * Portions Copyright (c) 1994, Regents of the University of California
      23             :  *
      24             :  * src/include/utils/palloc.h
      25             :  *
      26             :  *-------------------------------------------------------------------------
      27             :  */
      28             : #ifndef PALLOC_H
      29             : #define PALLOC_H
      30             : 
      31             : /*
      32             :  * Type MemoryContextData is declared in nodes/memnodes.h.  Most users
      33             :  * of memory allocation should just treat it as an abstract type, so we
      34             :  * do not provide the struct contents here.
      35             :  */
      36             : typedef struct MemoryContextData *MemoryContext;
      37             : 
      38             : /*
      39             :  * A memory context can have callback functions registered on it.  Any such
      40             :  * function will be called once just before the context is next reset or
      41             :  * deleted.  The MemoryContextCallback struct describing such a callback
      42             :  * typically would be allocated within the context itself, thereby avoiding
      43             :  * any need to manage it explicitly (the reset/delete action will free it).
      44             :  */
      45             : typedef void (*MemoryContextCallbackFunction) (void *arg);
      46             : 
      47             : typedef struct MemoryContextCallback
      48             : {
      49             :     MemoryContextCallbackFunction func; /* function to call */
      50             :     void       *arg;            /* argument to pass it */
      51             :     struct MemoryContextCallback *next; /* next in list of callbacks */
      52             : } MemoryContextCallback;
      53             : 
      54             : /*
      55             :  * CurrentMemoryContext is the default allocation context for palloc().
      56             :  * Avoid accessing it directly!  Instead, use MemoryContextSwitchTo()
      57             :  * to change the setting.
      58             :  */
      59             : extern PGDLLIMPORT MemoryContext CurrentMemoryContext;
      60             : 
      61             : /*
      62             :  * Flags for MemoryContextAllocExtended.
      63             :  */
      64             : #define MCXT_ALLOC_HUGE         0x01    /* allow huge allocation (> 1 GB) */
      65             : #define MCXT_ALLOC_NO_OOM       0x02    /* no failure if out-of-memory */
      66             : #define MCXT_ALLOC_ZERO         0x04    /* zero allocated memory */
      67             : 
      68             : /*
      69             :  * Fundamental memory-allocation operations (more are in utils/memutils.h)
      70             :  */
      71             : extern void *MemoryContextAlloc(MemoryContext context, Size size);
      72             : extern void *MemoryContextAllocZero(MemoryContext context, Size size);
      73             : extern void *MemoryContextAllocZeroAligned(MemoryContext context, Size size);
      74             : extern void *MemoryContextAllocExtended(MemoryContext context,
      75             :                                         Size size, int flags);
      76             : 
      77             : extern void *palloc(Size size);
      78             : extern void *palloc0(Size size);
      79             : extern void *palloc_extended(Size size, int flags);
      80             : extern void *repalloc(void *pointer, Size size);
      81             : extern void pfree(void *pointer);
      82             : 
      83             : /*
      84             :  * The result of palloc() is always word-aligned, so we can skip testing
      85             :  * alignment of the pointer when deciding which MemSet variant to use.
      86             :  * Note that this variant does not offer any advantage, and should not be
      87             :  * used, unless its "sz" argument is a compile-time constant; therefore, the
      88             :  * issue that it evaluates the argument multiple times isn't a problem in
      89             :  * practice.
      90             :  */
      91             : #define palloc0fast(sz) \
      92             :     ( MemSetTest(0, sz) ? \
      93             :         MemoryContextAllocZeroAligned(CurrentMemoryContext, sz) : \
      94             :         MemoryContextAllocZero(CurrentMemoryContext, sz) )
      95             : 
      96             : /* Higher-limit allocators. */
      97             : extern void *MemoryContextAllocHuge(MemoryContext context, Size size);
      98             : extern void *repalloc_huge(void *pointer, Size size);
      99             : 
     100             : /*
     101             :  * Although this header file is nominally backend-only, certain frontend
     102             :  * programs like pg_controldata include it via postgres.h.  For some compilers
     103             :  * it's necessary to hide the inline definition of MemoryContextSwitchTo in
     104             :  * this scenario; hence the #ifndef FRONTEND.
     105             :  */
     106             : 
     107             : #ifndef FRONTEND
     108             : static inline MemoryContext
     109   584547770 : MemoryContextSwitchTo(MemoryContext context)
     110             : {
     111   584547770 :     MemoryContext old = CurrentMemoryContext;
     112             : 
     113   584547770 :     CurrentMemoryContext = context;
     114   584547770 :     return old;
     115             : }
     116             : #endif                          /* FRONTEND */
     117             : 
     118             : /* Registration of memory context reset/delete callbacks */
     119             : extern void MemoryContextRegisterResetCallback(MemoryContext context,
     120             :                                                MemoryContextCallback *cb);
     121             : 
     122             : /*
     123             :  * These are like standard strdup() except the copied string is
     124             :  * allocated in a context, not with malloc().
     125             :  */
     126             : extern char *MemoryContextStrdup(MemoryContext context, const char *string);
     127             : extern char *pstrdup(const char *in);
     128             : extern char *pnstrdup(const char *in, Size len);
     129             : 
     130             : extern char *pchomp(const char *in);
     131             : 
     132             : /* sprintf into a palloc'd buffer --- these are in psprintf.c */
     133             : extern char *psprintf(const char *fmt,...) pg_attribute_printf(1, 2);
     134             : extern size_t pvsnprintf(char *buf, size_t len, const char *fmt, va_list args) pg_attribute_printf(3, 0);
     135             : 
     136             : #endif                          /* PALLOC_H */

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