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ab02d702ef
The code for unloading a library has been commented-out for over 12
years, ever since commit 602a9ef5a7, and we're
no closer to supporting it now than we were back then.
Nathan Bossart, reviewed by Michael Paquier and by me.
Discussion: http://postgr.es/m/Ynsc9bRL1caUSBSE@paquier.xyz
99 lines
2.7 KiB
C
99 lines
2.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* delay_execution.c
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* Test module to allow delay between parsing and execution of a query.
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*
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* The delay is implemented by taking and immediately releasing a specified
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* advisory lock. If another process has previously taken that lock, the
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* current process will be blocked until the lock is released; otherwise,
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* there's no effect. This allows an isolationtester script to reliably
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* test behaviors where some specified action happens in another backend
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* between parsing and execution of any desired query.
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*
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* Copyright (c) 2020-2022, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* src/test/modules/delay_execution/delay_execution.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <limits.h>
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#include "optimizer/planner.h"
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#include "utils/builtins.h"
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#include "utils/guc.h"
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#include "utils/inval.h"
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PG_MODULE_MAGIC;
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/* GUC: advisory lock ID to use. Zero disables the feature. */
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static int post_planning_lock_id = 0;
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/* Save previous planner hook user to be a good citizen */
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static planner_hook_type prev_planner_hook = NULL;
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/* Module load function */
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void _PG_init(void);
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/* planner_hook function to provide the desired delay */
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static PlannedStmt *
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delay_execution_planner(Query *parse, const char *query_string,
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int cursorOptions, ParamListInfo boundParams)
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{
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PlannedStmt *result;
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/* Invoke the planner, possibly via a previous hook user */
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if (prev_planner_hook)
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result = prev_planner_hook(parse, query_string, cursorOptions,
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boundParams);
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else
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result = standard_planner(parse, query_string, cursorOptions,
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boundParams);
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/* If enabled, delay by taking and releasing the specified lock */
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if (post_planning_lock_id != 0)
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{
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DirectFunctionCall1(pg_advisory_lock_int8,
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Int64GetDatum((int64) post_planning_lock_id));
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DirectFunctionCall1(pg_advisory_unlock_int8,
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Int64GetDatum((int64) post_planning_lock_id));
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/*
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* Ensure that we notice any pending invalidations, since the advisory
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* lock functions don't do this.
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*/
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AcceptInvalidationMessages();
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}
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return result;
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}
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/* Module load function */
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void
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_PG_init(void)
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{
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/* Set up the GUC to control which lock is used */
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DefineCustomIntVariable("delay_execution.post_planning_lock_id",
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"Sets the advisory lock ID to be locked/unlocked after planning.",
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"Zero disables the delay.",
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&post_planning_lock_id,
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0,
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0, INT_MAX,
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PGC_USERSET,
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0,
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NULL,
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NULL,
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NULL);
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MarkGUCPrefixReserved("delay_execution");
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/* Install our hook */
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prev_planner_hook = planner_hook;
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planner_hook = delay_execution_planner;
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}
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