>From 9505e5533972b4b027dabcb93644f974bfb4e6ac Mon Sep 17 00:00:00 2001 From: Petr Jelinek Date: Tue, 28 Mar 2017 23:24:34 +0200 Subject: [PATCH] Use library_name/function_name for loading main entry point of internal bgworkers --- src/backend/access/transam/parallel.c | 7 +-- src/backend/postmaster/bgworker.c | 76 ++++++++++++++++++++++++++------ src/include/access/parallel.h | 2 + src/test/modules/worker_spi/worker_spi.c | 6 ++- 4 files changed, 73 insertions(+), 18 deletions(-) diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c index cde0ed3..d2bed72 100644 --- a/src/backend/access/transam/parallel.c +++ b/src/backend/access/transam/parallel.c @@ -109,7 +109,6 @@ static dlist_head pcxt_list = DLIST_STATIC_INIT(pcxt_list); /* Private functions. */ static void HandleParallelMessage(ParallelContext *pcxt, int i, StringInfo msg); static void ParallelExtensionTrampoline(dsm_segment *seg, shm_toc *toc); -static void ParallelWorkerMain(Datum main_arg); static void WaitForParallelWorkersToExit(ParallelContext *pcxt); @@ -456,7 +455,9 @@ LaunchParallelWorkers(ParallelContext *pcxt) BGWORKER_SHMEM_ACCESS | BGWORKER_BACKEND_DATABASE_CONNECTION; worker.bgw_start_time = BgWorkerStart_ConsistentState; worker.bgw_restart_time = BGW_NEVER_RESTART; - worker.bgw_main = ParallelWorkerMain; + worker.bgw_main = NULL; + sprintf(worker.bgw_library_name, "postgres"); + sprintf(worker.bgw_function_name, "ParallelWorkerMain"); worker.bgw_main_arg = UInt32GetDatum(dsm_segment_handle(pcxt->seg)); worker.bgw_notify_pid = MyProcPid; memset(&worker.bgw_extra, 0, BGW_EXTRALEN); @@ -928,7 +929,7 @@ AtEOXact_Parallel(bool isCommit) /* * Main entrypoint for parallel workers. */ -static void +void ParallelWorkerMain(Datum main_arg) { dsm_segment *seg; diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c index 52bc4e9..31403bf 100644 --- a/src/backend/postmaster/bgworker.c +++ b/src/backend/postmaster/bgworker.c @@ -16,6 +16,7 @@ #include "miscadmin.h" #include "libpq/pqsignal.h" +#include "access/parallel.h" #include "postmaster/bgworker_internals.h" #include "postmaster/postmaster.h" #include "storage/barrier.h" @@ -94,6 +95,25 @@ struct BackgroundWorkerHandle static BackgroundWorkerArray *BackgroundWorkerData; /* + * List of internal background workers. These are used for mapping the + * function name to actual function when building with EXEC_BACKEND and also + * to allow these to be loaded outside of shared_preload_libraries. + */ +typedef struct InternalBGWorkerMain +{ + char *bgw_function_name; + bgworker_main_type bgw_main; +} InternalBGWorkerMain; + +static const InternalBGWorkerMain InternalBGWorkers[] = { + {"ParallelWorkerMain", ParallelWorkerMain}, + /* Dummy entry marking end of the array. */ + {NULL, NULL} +}; + +static bgworker_main_type GetInternalBgWorkerMain(BackgroundWorker *worker); + +/* * Calculate shared memory needed. */ Size @@ -695,22 +715,27 @@ StartBackgroundWorker(void) #endif } + /* For internal workers set the entry point to known function address. */ + entrypt = GetInternalBgWorkerMain(worker); + /* - * If bgw_main is set, we use that value as the initial entrypoint. - * However, if the library containing the entrypoint wasn't loaded at - * postmaster startup time, passing it as a direct function pointer is not - * possible. To work around that, we allow callers for whom a function - * pointer is not available to pass a library name (which will be loaded, - * if necessary) and a function name (which will be looked up in the named + * Otherwise, if bgw_main is set, we use that value as the initial + * entrypoint. This does not work well EXEC_BACKEND outside Windows but + * we keep the logic for backwards compatibility. In other cases use + * the entry point specified by library name (which will be loaded, if + * necessary) and a function name (which will be looked up in the named * library). */ - if (worker->bgw_main != NULL) - entrypt = worker->bgw_main; - else - entrypt = (bgworker_main_type) - load_external_function(worker->bgw_library_name, - worker->bgw_function_name, - true, NULL); + if (entrypt == NULL) + { + if (worker->bgw_main != NULL) + entrypt = worker->bgw_main; + else + entrypt = (bgworker_main_type) + load_external_function(worker->bgw_library_name, + worker->bgw_function_name, + true, NULL); + } /* * Note that in normal processes, we would call InitPostgres here. For a @@ -1050,3 +1075,28 @@ TerminateBackgroundWorker(BackgroundWorkerHandle *handle) if (signal_postmaster) SendPostmasterSignal(PMSIGNAL_BACKGROUND_WORKER_CHANGE); } + +/* + * Search the known internal worker array and return its main function + * pointer if found. + * + * Returns NULL if not known internal worker. + */ +static bgworker_main_type +GetInternalBgWorkerMain(BackgroundWorker *worker) +{ + int i; + + /* Internal workers always have to use postgres as library name. */ + if (strncmp(worker->bgw_library_name, "postgres", 8) != 0) + return NULL; + + for (i = 0; InternalBGWorkers[i].bgw_function_name; i++) + { + if (strncmp(InternalBGWorkers[i].bgw_function_name, + worker->bgw_function_name, BGW_MAXLEN) == 0) + return InternalBGWorkers[i].bgw_main; + } + + return NULL; +} diff --git a/src/include/access/parallel.h b/src/include/access/parallel.h index 2f8f36f..61dbfda 100644 --- a/src/include/access/parallel.h +++ b/src/include/access/parallel.h @@ -67,4 +67,6 @@ extern void AtEOXact_Parallel(bool isCommit); extern void AtEOSubXact_Parallel(bool isCommit, SubTransactionId mySubId); extern void ParallelWorkerReportLastRecEnd(XLogRecPtr last_xlog_end); +extern void ParallelWorkerMain(Datum main_arg); + #endif /* PARALLEL_H */ diff --git a/src/test/modules/worker_spi/worker_spi.c b/src/test/modules/worker_spi/worker_spi.c index 7c9a3eb..3711fba 100644 --- a/src/test/modules/worker_spi/worker_spi.c +++ b/src/test/modules/worker_spi/worker_spi.c @@ -346,7 +346,9 @@ _PG_init(void) BGWORKER_BACKEND_DATABASE_CONNECTION; worker.bgw_start_time = BgWorkerStart_RecoveryFinished; worker.bgw_restart_time = BGW_NEVER_RESTART; - worker.bgw_main = worker_spi_main; + worker.bgw_main = NULL; + sprintf(worker.bgw_library_name, "worker_spi"); + sprintf(worker.bgw_function_name, "worker_spi_main"); worker.bgw_notify_pid = 0; /* @@ -377,7 +379,7 @@ worker_spi_launch(PG_FUNCTION_ARGS) BGWORKER_BACKEND_DATABASE_CONNECTION; worker.bgw_start_time = BgWorkerStart_RecoveryFinished; worker.bgw_restart_time = BGW_NEVER_RESTART; - worker.bgw_main = NULL; /* new worker might not have library loaded */ + worker.bgw_main = NULL; sprintf(worker.bgw_library_name, "worker_spi"); sprintf(worker.bgw_function_name, "worker_spi_main"); snprintf(worker.bgw_name, BGW_MAXLEN, "worker %d", i); -- 2.7.4