Branch data     Line data    Source code

       1                 :             : /*-------------------------------------------------------------------------
       2                 :             :  *
       3                 :             :  * delay_execution.c
       4                 :             :  *      Test module to allow delay between parsing and execution of a query.
       5                 :             :  *
       6                 :             :  * The delay is implemented by taking and immediately releasing a specified
       7                 :             :  * advisory lock.  If another process has previously taken that lock, the
       8                 :             :  * current process will be blocked until the lock is released; otherwise,
       9                 :             :  * there's no effect.  This allows an isolationtester script to reliably
      10                 :             :  * test behaviors where some specified action happens in another backend
      11                 :             :  * between parsing and execution of any desired query.
      12                 :             :  *
      13                 :             :  * Copyright (c) 2020-2026, PostgreSQL Global Development Group
      14                 :             :  *
      15                 :             :  * IDENTIFICATION
      16                 :             :  *    src/test/modules/delay_execution/delay_execution.c
      17                 :             :  *
      18                 :             :  *-------------------------------------------------------------------------
      19                 :             :  */
      20                 :             : 
      21                 :             : #include "postgres.h"
      22                 :             : 
      23                 :             : #include <limits.h>
      24                 :             : 
      25                 :             : #include "optimizer/planner.h"
      26                 :             : #include "utils/fmgrprotos.h"
      27                 :             : #include "utils/guc.h"
      28                 :             : #include "utils/inval.h"
      29                 :             : 
      30                 :             : 
      31                 :           2 : PG_MODULE_MAGIC;
      32                 :             : 
      33                 :             : /* GUC: advisory lock ID to use.  Zero disables the feature. */
      34                 :             : static int  post_planning_lock_id = 0;
      35                 :             : 
      36                 :             : /* Save previous planner hook user to be a good citizen */
      37                 :             : static planner_hook_type prev_planner_hook = NULL;
      38                 :             : 
      39                 :             : 
      40                 :             : /* planner_hook function to provide the desired delay */
      41                 :             : static PlannedStmt *
      42                 :          15 : delay_execution_planner(Query *parse, const char *query_string,
      43                 :             :                         int cursorOptions, ParamListInfo boundParams,
      44                 :             :                         ExplainState *es)
      45                 :             : {
      46                 :             :     PlannedStmt *result;
      47                 :             : 
      48                 :             :     /* Invoke the planner, possibly via a previous hook user */
      49         [ -  + ]:          15 :     if (prev_planner_hook)
      50                 :           0 :         result = prev_planner_hook(parse, query_string, cursorOptions,
      51                 :             :                                    boundParams, es);
      52                 :             :     else
      53                 :          15 :         result = standard_planner(parse, query_string, cursorOptions,
      54                 :             :                                   boundParams, es);
      55                 :             : 
      56                 :             :     /* If enabled, delay by taking and releasing the specified lock */
      57         [ +  - ]:          15 :     if (post_planning_lock_id != 0)
      58                 :             :     {
      59                 :          15 :         DirectFunctionCall1(pg_advisory_lock_int8,
      60                 :             :                             Int64GetDatum((int64) post_planning_lock_id));
      61                 :          15 :         DirectFunctionCall1(pg_advisory_unlock_int8,
      62                 :             :                             Int64GetDatum((int64) post_planning_lock_id));
      63                 :             : 
      64                 :             :         /*
      65                 :             :          * Ensure that we notice any pending invalidations, since the advisory
      66                 :             :          * lock functions don't do this.
      67                 :             :          */
      68                 :          15 :         AcceptInvalidationMessages();
      69                 :             :     }
      70                 :             : 
      71                 :          15 :     return result;
      72                 :             : }
      73                 :             : 
      74                 :             : /* Module load function */
      75                 :             : void
      76                 :           2 : _PG_init(void)
      77                 :             : {
      78                 :             :     /* Set up the GUC to control which lock is used */
      79                 :           2 :     DefineCustomIntVariable("delay_execution.post_planning_lock_id",
      80                 :             :                             "Sets the advisory lock ID to be locked/unlocked after planning.",
      81                 :             :                             "Zero disables the delay.",
      82                 :             :                             &post_planning_lock_id,
      83                 :             :                             0,
      84                 :             :                             0, INT_MAX,
      85                 :             :                             PGC_USERSET,
      86                 :             :                             0,
      87                 :             :                             NULL,
      88                 :             :                             NULL,
      89                 :             :                             NULL);
      90                 :             : 
      91                 :           2 :     MarkGUCPrefixReserved("delay_execution");
      92                 :             : 
      93                 :             :     /* Install our hook */
      94                 :           2 :     prev_planner_hook = planner_hook;
      95                 :           2 :     planner_hook = delay_execution_planner;
      96                 :           2 : }