#include "access/xlog.h"
#include "catalog/namespace.h"
#include "commands/async.h"
+#include "executor/execParallel.h"
#include "libpq/libpq.h"
#include "libpq/pqformat.h"
#include "libpq/pqmq.h"
#define PARALLEL_KEY_TRANSACTION_SNAPSHOT UINT64CONST(0xFFFFFFFFFFFF0006)
#define PARALLEL_KEY_ACTIVE_SNAPSHOT UINT64CONST(0xFFFFFFFFFFFF0007)
#define PARALLEL_KEY_TRANSACTION_STATE UINT64CONST(0xFFFFFFFFFFFF0008)
-#define PARALLEL_KEY_EXTENSION_TRAMPOLINE UINT64CONST(0xFFFFFFFFFFFF0009)
+#define PARALLEL_KEY_ENTRYPOINT UINT64CONST(0xFFFFFFFFFFFF0009)
/* Fixed-size parallel state. */
typedef struct FixedParallelState
pid_t parallel_master_pid;
BackendId parallel_master_backend_id;
- /* Entrypoint for parallel workers. */
- parallel_worker_main_type entrypoint;
-
/* Mutex protects remaining fields. */
slock_t mutex;
/* List of active parallel contexts. */
static dlist_head pcxt_list = DLIST_STATIC_INIT(pcxt_list);
+/*
+ * List of internal parallel worker entry points. We need this for
+ * reasons explained in LookupParallelWorkerFunction(), below.
+ */
+static const struct
+{
+ const char *fn_name;
+ parallel_worker_main_type fn_addr;
+} InternalParallelWorkers[] =
+
+{
+ {
+ "ParallelQueryMain", ParallelQueryMain
+ }
+};
+
/* Private functions. */
static void HandleParallelMessage(ParallelContext *pcxt, int i, StringInfo msg);
-static void ParallelExtensionTrampoline(dsm_segment *seg, shm_toc *toc);
static void WaitForParallelWorkersToExit(ParallelContext *pcxt);
+static parallel_worker_main_type LookupParallelWorkerFunction(const char *libraryname, const char *funcname);
/*
* destroyed before exiting the current subtransaction.
*/
ParallelContext *
-CreateParallelContext(parallel_worker_main_type entrypoint, int nworkers)
+CreateParallelContext(const char *library_name, const char *function_name,
+ int nworkers)
{
MemoryContext oldcontext;
ParallelContext *pcxt;
pcxt = palloc0(sizeof(ParallelContext));
pcxt->subid = GetCurrentSubTransactionId();
pcxt->nworkers = nworkers;
- pcxt->entrypoint = entrypoint;
+ pcxt->library_name = pstrdup(library_name);
+ pcxt->function_name = pstrdup(function_name);
pcxt->error_context_stack = error_context_stack;
shm_toc_initialize_estimator(&pcxt->estimator);
dlist_push_head(&pcxt_list, &pcxt->node);
return pcxt;
}
-/*
- * Establish a new parallel context that calls a function provided by an
- * extension. This works around the fact that the library might get mapped
- * at a different address in each backend.
- */
-ParallelContext *
-CreateParallelContextForExternalFunction(char *library_name,
- char *function_name,
- int nworkers)
-{
- MemoryContext oldcontext;
- ParallelContext *pcxt;
-
- /* We might be running in a very short-lived memory context. */
- oldcontext = MemoryContextSwitchTo(TopTransactionContext);
-
- /* Create the context. */
- pcxt = CreateParallelContext(ParallelExtensionTrampoline, nworkers);
- pcxt->library_name = pstrdup(library_name);
- pcxt->function_name = pstrdup(function_name);
-
- /* Restore previous memory context. */
- MemoryContextSwitchTo(oldcontext);
-
- return pcxt;
-}
-
/*
* Establish the dynamic shared memory segment for a parallel context and
* copy state and other bookkeeping information that will be needed by
pcxt->nworkers));
shm_toc_estimate_keys(&pcxt->estimator, 1);
- /* Estimate how much we'll need for extension entrypoint info. */
- if (pcxt->library_name != NULL)
- {
- Assert(pcxt->entrypoint == ParallelExtensionTrampoline);
- Assert(pcxt->function_name != NULL);
- shm_toc_estimate_chunk(&pcxt->estimator, strlen(pcxt->library_name)
- + strlen(pcxt->function_name) + 2);
- shm_toc_estimate_keys(&pcxt->estimator, 1);
- }
+ /* Estimate how much we'll need for the entrypoint info. */
+ shm_toc_estimate_chunk(&pcxt->estimator, strlen(pcxt->library_name) +
+ strlen(pcxt->function_name) + 2);
+ shm_toc_estimate_keys(&pcxt->estimator, 1);
}
/*
fps->parallel_master_pgproc = MyProc;
fps->parallel_master_pid = MyProcPid;
fps->parallel_master_backend_id = MyBackendId;
- fps->entrypoint = pcxt->entrypoint;
SpinLockInit(&fps->mutex);
fps->last_xlog_end = 0;
shm_toc_insert(pcxt->toc, PARALLEL_KEY_FIXED, fps);
char *asnapspace;
char *tstatespace;
char *error_queue_space;
+ char *entrypointstate;
+ Size lnamelen;
/* Serialize shared libraries we have loaded. */
libraryspace = shm_toc_allocate(pcxt->toc, library_len);
}
shm_toc_insert(pcxt->toc, PARALLEL_KEY_ERROR_QUEUE, error_queue_space);
- /* Serialize extension entrypoint information. */
- if (pcxt->library_name != NULL)
- {
- Size lnamelen = strlen(pcxt->library_name);
- char *extensionstate;
-
- extensionstate = shm_toc_allocate(pcxt->toc, lnamelen
- + strlen(pcxt->function_name) + 2);
- strcpy(extensionstate, pcxt->library_name);
- strcpy(extensionstate + lnamelen + 1, pcxt->function_name);
- shm_toc_insert(pcxt->toc, PARALLEL_KEY_EXTENSION_TRAMPOLINE,
- extensionstate);
- }
+ /*
+ * Serialize entrypoint information. It's unsafe to pass function
+ * pointers across processes, as the function pointer may be different
+ * in each process in EXEC_BACKEND builds, so we always pass library
+ * and function name. (We use library name "postgres" for functions
+ * in the core backend.)
+ */
+ lnamelen = strlen(pcxt->library_name);
+ entrypointstate = shm_toc_allocate(pcxt->toc, lnamelen +
+ strlen(pcxt->function_name) + 2);
+ strcpy(entrypointstate, pcxt->library_name);
+ strcpy(entrypointstate + lnamelen + 1, pcxt->function_name);
+ shm_toc_insert(pcxt->toc, PARALLEL_KEY_ENTRYPOINT, entrypointstate);
}
/* Restore previous memory context. */
}
/* Free memory. */
+ pfree(pcxt->library_name);
+ pfree(pcxt->function_name);
pfree(pcxt);
}
shm_mq *mq;
shm_mq_handle *mqh;
char *libraryspace;
+ char *entrypointstate;
+ char *library_name;
+ char *function_name;
+ parallel_worker_main_type entrypt;
char *gucspace;
char *combocidspace;
char *tsnapspace;
Assert(libraryspace != NULL);
RestoreLibraryState(libraryspace);
+ /*
+ * Identify the entry point to be called. In theory this could result in
+ * loading an additional library, though most likely the entry point is in
+ * the core backend or in a library we just loaded.
+ */
+ entrypointstate = shm_toc_lookup(toc, PARALLEL_KEY_ENTRYPOINT);
+ Assert(entrypointstate != NULL);
+ library_name = entrypointstate;
+ function_name = entrypointstate + strlen(library_name) + 1;
+
+ entrypt = LookupParallelWorkerFunction(library_name, function_name);
+
/* Restore database connection. */
BackgroundWorkerInitializeConnectionByOid(fps->database_id,
fps->authenticated_user_id);
/*
* Time to do the real work: invoke the caller-supplied code.
- *
- * If you get a crash at this line, see the comments for
- * ParallelExtensionTrampoline.
*/
- fps->entrypoint(seg, toc);
+ entrypt(seg, toc);
/* Must exit parallel mode to pop active snapshot. */
ExitParallelMode();
pq_putmessage('X', NULL, 0);
}
-/*
- * It's unsafe for the entrypoint invoked by ParallelWorkerMain to be a
- * function living in a dynamically loaded module, because the module might
- * not be loaded in every process, or might be loaded but not at the same
- * address. To work around that problem, CreateParallelContextForExtension()
- * arranges to call this function rather than calling the extension-provided
- * function directly; and this function then looks up the real entrypoint and
- * calls it.
- */
-static void
-ParallelExtensionTrampoline(dsm_segment *seg, shm_toc *toc)
-{
- char *extensionstate;
- char *library_name;
- char *function_name;
- parallel_worker_main_type entrypt;
-
- extensionstate = shm_toc_lookup(toc, PARALLEL_KEY_EXTENSION_TRAMPOLINE);
- Assert(extensionstate != NULL);
- library_name = extensionstate;
- function_name = extensionstate + strlen(library_name) + 1;
-
- entrypt = (parallel_worker_main_type)
- load_external_function(library_name, function_name, true, NULL);
- entrypt(seg, toc);
-}
-
/*
* Update shared memory with the ending location of the last WAL record we
* wrote, if it's greater than the value already stored there.
fps->last_xlog_end = last_xlog_end;
SpinLockRelease(&fps->mutex);
}
+
+/*
+ * Look up (and possibly load) a parallel worker entry point function.
+ *
+ * For functions contained in the core code, we use library name "postgres"
+ * and consult the InternalParallelWorkers array. External functions are
+ * looked up, and loaded if necessary, using load_external_function().
+ *
+ * The point of this is to pass function names as strings across process
+ * boundaries. We can't pass actual function addresses because of the
+ * possibility that the function has been loaded at a different address
+ * in a different process. This is obviously a hazard for functions in
+ * loadable libraries, but it can happen even for functions in the core code
+ * on platforms using EXEC_BACKEND (e.g., Windows).
+ *
+ * At some point it might be worthwhile to get rid of InternalParallelWorkers[]
+ * in favor of applying load_external_function() for core functions too;
+ * but that raises portability issues that are not worth addressing now.
+ */
+static parallel_worker_main_type
+LookupParallelWorkerFunction(const char *libraryname, const char *funcname)
+{
+ /*
+ * If the function is to be loaded from postgres itself, search the
+ * InternalParallelWorkers array.
+ */
+ if (strcmp(libraryname, "postgres") == 0)
+ {
+ int i;
+
+ for (i = 0; i < lengthof(InternalParallelWorkers); i++)
+ {
+ if (strcmp(InternalParallelWorkers[i].fn_name, funcname) == 0)
+ return InternalParallelWorkers[i].fn_addr;
+ }
+
+ /* We can only reach this by programming error. */
+ elog(ERROR, "internal function \"%s\" not found", funcname);
+ }
+
+ /* Otherwise load from external library. */
+ return (parallel_worker_main_type)
+ load_external_function(libraryname, funcname, true, NULL);
+}
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.
+ * List of internal background worker entry points. We need this for
+ * reasons explained in LookupBackgroundWorkerFunction(), below.
*/
-typedef struct InternalBGWorkerMain
+static const struct
{
- char *bgw_function_name;
- bgworker_main_type bgw_main;
-} InternalBGWorkerMain;
-
-static const InternalBGWorkerMain InternalBGWorkers[] = {
- {"ParallelWorkerMain", ParallelWorkerMain},
- {"ApplyLauncherMain", ApplyLauncherMain},
- {"ApplyWorkerMain", ApplyWorkerMain},
- /* Dummy entry marking end of the array. */
- {NULL, NULL}
+ const char *fn_name;
+ bgworker_main_type fn_addr;
+} InternalBGWorkers[] =
+
+{
+ {
+ "ParallelWorkerMain", ParallelWorkerMain
+ },
+ {
+ "ApplyLauncherMain", ApplyLauncherMain
+ },
+ {
+ "ApplyWorkerMain", ApplyWorkerMain
+ }
};
-static bgworker_main_type GetInternalBgWorkerMain(BackgroundWorker *worker);
+/* Private functions. */
+static bgworker_main_type LookupBackgroundWorkerFunction(const char *libraryname, const char *funcname);
+
/*
* Calculate shared memory needed.
}
/*
- * For internal workers set the entry point to known function address.
- * Otherwise 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).
+ * Look up the entry point function, loading its library if necessary.
*/
- entrypt = GetInternalBgWorkerMain(worker);
-
- if (entrypt == NULL)
- entrypt = (bgworker_main_type)
- load_external_function(worker->bgw_library_name,
- worker->bgw_function_name,
- true, NULL);
+ entrypt = LookupBackgroundWorkerFunction(worker->bgw_library_name,
+ worker->bgw_function_name);
/*
* Note that in normal processes, we would call InitPostgres here. For a
}
/*
- * Register a new background worker while processing shared_preload_libraries.
+ * Register a new static background worker.
*
- * This can only be called in the _PG_init function of a module library
- * that's loaded by shared_preload_libraries; otherwise it has no effect.
+ * This can only be called directly from postmaster or in the _PG_init
+ * function of a module library that's loaded by shared_preload_libraries;
+ * otherwise it will have no effect.
*/
void
RegisterBackgroundWorker(BackgroundWorker *worker)
(errmsg("registering background worker \"%s\"", worker->bgw_name)));
if (!process_shared_preload_libraries_in_progress &&
- GetInternalBgWorkerMain(worker) == NULL)
+ strcmp(worker->bgw_library_name, "postgres") != 0)
{
if (!IsUnderPostmaster)
ereport(LOG,
}
/*
- * Search the known internal worker array and return its main function
- * pointer if found.
+ * Look up (and possibly load) a bgworker entry point function.
+ *
+ * For functions contained in the core code, we use library name "postgres"
+ * and consult the InternalBGWorkers array. External functions are
+ * looked up, and loaded if necessary, using load_external_function().
*
- * Returns NULL if not known internal worker.
+ * The point of this is to pass function names as strings across process
+ * boundaries. We can't pass actual function addresses because of the
+ * possibility that the function has been loaded at a different address
+ * in a different process. This is obviously a hazard for functions in
+ * loadable libraries, but it can happen even for functions in the core code
+ * on platforms using EXEC_BACKEND (e.g., Windows).
+ *
+ * At some point it might be worthwhile to get rid of InternalBGWorkers[]
+ * in favor of applying load_external_function() for core functions too;
+ * but that raises portability issues that are not worth addressing now.
*/
static bgworker_main_type
-GetInternalBgWorkerMain(BackgroundWorker *worker)
+LookupBackgroundWorkerFunction(const char *libraryname, const char *funcname)
{
- int i;
+ /*
+ * If the function is to be loaded from postgres itself, search the
+ * InternalBGWorkers array.
+ */
+ if (strcmp(libraryname, "postgres") == 0)
+ {
+ int i;
- /* Internal workers always have to use postgres as library name. */
- if (strncmp(worker->bgw_library_name, "postgres", BGW_MAXLEN) != 0)
- return NULL;
+ for (i = 0; i < lengthof(InternalBGWorkers); i++)
+ {
+ if (strcmp(InternalBGWorkers[i].fn_name, funcname) == 0)
+ return InternalBGWorkers[i].fn_addr;
+ }
- 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;
+ /* We can only reach this by programming error. */
+ elog(ERROR, "internal function \"%s\" not found", funcname);
}
- return NULL;
+ /* Otherwise load from external library. */
+ return (bgworker_main_type)
+ load_external_function(libraryname, funcname, true, NULL);
}
projects / postgresql / commitdiff