TLA  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) 2020-2023, 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/builtins.h"
      27                 : #include "utils/guc.h"
      28                 : #include "utils/inval.h"
      29                 : 
      30                 : 
      31 CBC           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 ECB             : 
      40                 : /* planner_hook function to provide the desired delay */
      41                 : static PlannedStmt *
      42 GIC          15 : delay_execution_planner(Query *parse, const char *query_string,
      43                 :                         int cursorOptions, ParamListInfo boundParams)
      44                 : {
      45 ECB             :     PlannedStmt *result;
      46 EUB             : 
      47                 :     /* Invoke the planner, possibly via a previous hook user */
      48 GIC          15 :     if (prev_planner_hook)
      49 LBC           0 :         result = prev_planner_hook(parse, query_string, cursorOptions,
      50                 :                                    boundParams);
      51                 :     else
      52 GIC          15 :         result = standard_planner(parse, query_string, cursorOptions,
      53 ECB             :                                   boundParams);
      54                 : 
      55                 :     /* If enabled, delay by taking and releasing the specified lock */
      56 GIC          15 :     if (post_planning_lock_id != 0)
      57 ECB             :     {
      58 GIC          15 :         DirectFunctionCall1(pg_advisory_lock_int8,
      59                 :                             Int64GetDatum((int64) post_planning_lock_id));
      60              15 :         DirectFunctionCall1(pg_advisory_unlock_int8,
      61                 :                             Int64GetDatum((int64) post_planning_lock_id));
      62                 : 
      63                 :         /*
      64 ECB             :          * Ensure that we notice any pending invalidations, since the advisory
      65                 :          * lock functions don't do this.
      66                 :          */
      67 CBC          15 :         AcceptInvalidationMessages();
      68                 :     }
      69                 : 
      70 GIC          15 :     return result;
      71                 : }
      72 ECB             : 
      73                 : /* Module load function */
      74                 : void
      75 CBC           2 : _PG_init(void)
      76                 : {
      77                 :     /* Set up the GUC to control which lock is used */
      78 GIC           2 :     DefineCustomIntVariable("delay_execution.post_planning_lock_id",
      79                 :                             "Sets the advisory lock ID to be locked/unlocked after planning.",
      80                 :                             "Zero disables the delay.",
      81                 :                             &post_planning_lock_id,
      82                 :                             0,
      83                 :                             0, INT_MAX,
      84                 :                             PGC_USERSET,
      85                 :                             0,
      86                 :                             NULL,
      87 ECB             :                             NULL,
      88                 :                             NULL);
      89                 : 
      90 CBC           2 :     MarkGUCPrefixReserved("delay_execution");
      91 ECB             : 
      92                 :     /* Install our hook */
      93 GIC           2 :     prev_planner_hook = planner_hook;
      94               2 :     planner_hook = delay_execution_planner;
      95               2 : }