LCOV - code coverage report
Current view: top level - contrib/postgres_fdw - shippable.c (source / functions) Hit Total Coverage
Test: PostgreSQL 11devel Lines: 40 41 97.6 %
Date: 2018-02-20 09:20:13 Functions: 5 5 100.0 %
Legend: Lines: hit not hit | Branches: + taken - not taken # not executed Branches: 20 26 76.9 %

           Branch data     Line data    Source code
       1                 :            : /*-------------------------------------------------------------------------
       2                 :            :  *
       3                 :            :  * shippable.c
       4                 :            :  *    Determine which database objects are shippable to a remote server.
       5                 :            :  *
       6                 :            :  * We need to determine whether particular functions, operators, and indeed
       7                 :            :  * data types are shippable to a remote server for execution --- that is,
       8                 :            :  * do they exist and have the same behavior remotely as they do locally?
       9                 :            :  * Built-in objects are generally considered shippable.  Other objects can
      10                 :            :  * be shipped if they are white-listed by the user.
      11                 :            :  *
      12                 :            :  * Note: there are additional filter rules that prevent shipping mutable
      13                 :            :  * functions or functions using nonportable collations.  Those considerations
      14                 :            :  * need not be accounted for here.
      15                 :            :  *
      16                 :            :  * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
      17                 :            :  *
      18                 :            :  * IDENTIFICATION
      19                 :            :  *    contrib/postgres_fdw/shippable.c
      20                 :            :  *
      21                 :            :  *-------------------------------------------------------------------------
      22                 :            :  */
      23                 :            : 
      24                 :            : #include "postgres.h"
      25                 :            : 
      26                 :            : #include "postgres_fdw.h"
      27                 :            : 
      28                 :            : #include "access/transam.h"
      29                 :            : #include "catalog/dependency.h"
      30                 :            : #include "utils/hsearch.h"
      31                 :            : #include "utils/inval.h"
      32                 :            : #include "utils/syscache.h"
      33                 :            : 
      34                 :            : 
      35                 :            : /* Hash table for caching the results of shippability lookups */
      36                 :            : static HTAB *ShippableCacheHash = NULL;
      37                 :            : 
      38                 :            : /*
      39                 :            :  * Hash key for shippability lookups.  We include the FDW server OID because
      40                 :            :  * decisions may differ per-server.  Otherwise, objects are identified by
      41                 :            :  * their (local!) OID and catalog OID.
      42                 :            :  */
      43                 :            : typedef struct
      44                 :            : {
      45                 :            :     /* XXX we assume this struct contains no padding bytes */
      46                 :            :     Oid         objid;          /* function/operator/type OID */
      47                 :            :     Oid         classid;        /* OID of its catalog (pg_proc, etc) */
      48                 :            :     Oid         serverid;       /* FDW server we are concerned with */
      49                 :            : } ShippableCacheKey;
      50                 :            : 
      51                 :            : typedef struct
      52                 :            : {
      53                 :            :     ShippableCacheKey key;      /* hash key - must be first */
      54                 :            :     bool        shippable;
      55                 :            : } ShippableCacheEntry;
      56                 :            : 
      57                 :            : 
      58                 :            : /*
      59                 :            :  * Flush cache entries when pg_foreign_server is updated.
      60                 :            :  *
      61                 :            :  * We do this because of the possibility of ALTER SERVER being used to change
      62                 :            :  * a server's extensions option.  We do not currently bother to check whether
      63                 :            :  * objects' extension membership changes once a shippability decision has been
      64                 :            :  * made for them, however.
      65                 :            :  */
      66                 :            : static void
      67                 :         28 : InvalidateShippableCacheCallback(Datum arg, int cacheid, uint32 hashvalue)
      68                 :            : {
      69                 :            :     HASH_SEQ_STATUS status;
      70                 :            :     ShippableCacheEntry *entry;
      71                 :            : 
      72                 :            :     /*
      73                 :            :      * In principle we could flush only cache entries relating to the
      74                 :            :      * pg_foreign_server entry being outdated; but that would be more
      75                 :            :      * complicated, and it's probably not worth the trouble.  So for now, just
      76                 :            :      * flush all entries.
      77                 :            :      */
      78                 :         28 :     hash_seq_init(&status, ShippableCacheHash);
      79         [ +  + ]:         50 :     while ((entry = (ShippableCacheEntry *) hash_seq_search(&status)) != NULL)
      80                 :            :     {
      81         [ -  + ]:         22 :         if (hash_search(ShippableCacheHash,
      82                 :         22 :                         (void *) &entry->key,
      83                 :            :                         HASH_REMOVE,
      84                 :            :                         NULL) == NULL)
      85                 :          0 :             elog(ERROR, "hash table corrupted");
      86                 :            :     }
      87                 :         28 : }
      88                 :            : 
      89                 :            : /*
      90                 :            :  * Initialize the backend-lifespan cache of shippability decisions.
      91                 :            :  */
      92                 :            : static void
      93                 :          2 : InitializeShippableCache(void)
      94                 :            : {
      95                 :            :     HASHCTL     ctl;
      96                 :            : 
      97                 :            :     /* Create the hash table. */
      98 [ +  - ][ +  - ]:         28 :     MemSet(&ctl, 0, sizeof(ctl));
         [ +  - ][ +  - ]
                 [ +  + ]
      99                 :          2 :     ctl.keysize = sizeof(ShippableCacheKey);
     100                 :          2 :     ctl.entrysize = sizeof(ShippableCacheEntry);
     101                 :          2 :     ShippableCacheHash =
     102                 :          2 :         hash_create("Shippability cache", 256, &ctl, HASH_ELEM | HASH_BLOBS);
     103                 :            : 
     104                 :            :     /* Set up invalidation callback on pg_foreign_server. */
     105                 :          2 :     CacheRegisterSyscacheCallback(FOREIGNSERVEROID,
     106                 :            :                                   InvalidateShippableCacheCallback,
     107                 :            :                                   (Datum) 0);
     108                 :          2 : }
     109                 :            : 
     110                 :            : /*
     111                 :            :  * Returns true if given object (operator/function/type) is shippable
     112                 :            :  * according to the server options.
     113                 :            :  *
     114                 :            :  * Right now "shippability" is exclusively a function of whether the object
     115                 :            :  * belongs to an extension declared by the user.  In the future we could
     116                 :            :  * additionally have a whitelist of functions/operators declared one at a time.
     117                 :            :  */
     118                 :            : static bool
     119                 :         22 : lookup_shippable(Oid objectId, Oid classId, PgFdwRelationInfo *fpinfo)
     120                 :            : {
     121                 :            :     Oid         extensionOid;
     122                 :            : 
     123                 :            :     /*
     124                 :            :      * Is object a member of some extension?  (Note: this is a fairly
     125                 :            :      * expensive lookup, which is why we try to cache the results.)
     126                 :            :      */
     127                 :         22 :     extensionOid = getExtensionOfObject(classId, objectId);
     128                 :            : 
     129                 :            :     /* If so, is that extension in fpinfo->shippable_extensions? */
     130   [ +  +  +  - ]:         32 :     if (OidIsValid(extensionOid) &&
     131                 :         10 :         list_member_oid(fpinfo->shippable_extensions, extensionOid))
     132                 :         10 :         return true;
     133                 :            : 
     134                 :         12 :     return false;
     135                 :            : }
     136                 :            : 
     137                 :            : /*
     138                 :            :  * Return true if given object is one of PostgreSQL's built-in objects.
     139                 :            :  *
     140                 :            :  * We use FirstBootstrapObjectId as the cutoff, so that we only consider
     141                 :            :  * objects with hand-assigned OIDs to be "built in", not for instance any
     142                 :            :  * function or type defined in the information_schema.
     143                 :            :  *
     144                 :            :  * Our constraints for dealing with types are tighter than they are for
     145                 :            :  * functions or operators: we want to accept only types that are in pg_catalog,
     146                 :            :  * else deparse_type_name might incorrectly fail to schema-qualify their names.
     147                 :            :  * Thus we must exclude information_schema types.
     148                 :            :  *
     149                 :            :  * XXX there is a problem with this, which is that the set of built-in
     150                 :            :  * objects expands over time.  Something that is built-in to us might not
     151                 :            :  * be known to the remote server, if it's of an older version.  But keeping
     152                 :            :  * track of that would be a huge exercise.
     153                 :            :  */
     154                 :            : bool
     155                 :      11200 : is_builtin(Oid objectId)
     156                 :            : {
     157                 :      11200 :     return (objectId < FirstBootstrapObjectId);
     158                 :            : }
     159                 :            : 
     160                 :            : /*
     161                 :            :  * is_shippable
     162                 :            :  *     Is this object (function/operator/type) shippable to foreign server?
     163                 :            :  */
     164                 :            : bool
     165                 :      10742 : is_shippable(Oid objectId, Oid classId, PgFdwRelationInfo *fpinfo)
     166                 :            : {
     167                 :            :     ShippableCacheKey key;
     168                 :            :     ShippableCacheEntry *entry;
     169                 :            : 
     170                 :            :     /* Built-in objects are presumed shippable. */
     171         [ +  + ]:      10742 :     if (is_builtin(objectId))
     172                 :      10628 :         return true;
     173                 :            : 
     174                 :            :     /* Otherwise, give up if user hasn't specified any shippable extensions. */
     175         [ +  + ]:        114 :     if (fpinfo->shippable_extensions == NIL)
     176                 :         34 :         return false;
     177                 :            : 
     178                 :            :     /* Initialize cache if first time through. */
     179         [ +  + ]:         80 :     if (!ShippableCacheHash)
     180                 :          2 :         InitializeShippableCache();
     181                 :            : 
     182                 :            :     /* Set up cache hash key */
     183                 :         80 :     key.objid = objectId;
     184                 :         80 :     key.classid = classId;
     185                 :         80 :     key.serverid = fpinfo->server->serverid;
     186                 :            : 
     187                 :            :     /* See if we already cached the result. */
     188                 :         80 :     entry = (ShippableCacheEntry *)
     189                 :         80 :         hash_search(ShippableCacheHash,
     190                 :            :                     (void *) &key,
     191                 :            :                     HASH_FIND,
     192                 :            :                     NULL);
     193                 :            : 
     194         [ +  + ]:         80 :     if (!entry)
     195                 :            :     {
     196                 :            :         /* Not found in cache, so perform shippability lookup. */
     197                 :         22 :         bool        shippable = lookup_shippable(objectId, classId, fpinfo);
     198                 :            : 
     199                 :            :         /*
     200                 :            :          * Don't create a new hash entry until *after* we have the shippable
     201                 :            :          * result in hand, as the underlying catalog lookups might trigger a
     202                 :            :          * cache invalidation.
     203                 :            :          */
     204                 :         22 :         entry = (ShippableCacheEntry *)
     205                 :         22 :             hash_search(ShippableCacheHash,
     206                 :            :                         (void *) &key,
     207                 :            :                         HASH_ENTER,
     208                 :            :                         NULL);
     209                 :            : 
     210                 :         22 :         entry->shippable = shippable;
     211                 :            :     }
     212                 :            : 
     213                 :      10742 :     return entry->shippable;
     214                 :            : }

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