1 files changed, 285 insertions, 0 deletions
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
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+++ b/src/backend/storage/ipc/ipci.c
@@ -0,0 +1,285 @@
+/*-------------------------------------------------------------------------
+ *
+ * ipci.c
+ *	  POSTGRES inter-process communication initialization code.
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/storage/ipc/ipci.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/clog.h"
+#include "access/commit_ts.h"
+#include "access/heapam.h"
+#include "access/multixact.h"
+#include "access/nbtree.h"
+#include "access/subtrans.h"
+#include "access/twophase.h"
+#include "commands/async.h"
+#include "miscadmin.h"
+#include "pgstat.h"
+#include "postmaster/autovacuum.h"
+#include "postmaster/bgworker_internals.h"
+#include "postmaster/bgwriter.h"
+#include "postmaster/postmaster.h"
+#include "replication/logicallauncher.h"
+#include "replication/origin.h"
+#include "replication/slot.h"
+#include "replication/walreceiver.h"
+#include "replication/walsender.h"
+#include "storage/bufmgr.h"
+#include "storage/dsm.h"
+#include "storage/ipc.h"
+#include "storage/pg_shmem.h"
+#include "storage/pmsignal.h"
+#include "storage/predicate.h"
+#include "storage/proc.h"
+#include "storage/procarray.h"
+#include "storage/procsignal.h"
+#include "storage/sinvaladt.h"
+#include "storage/spin.h"
+#include "utils/snapmgr.h"
+
+/* GUCs */
+int			shared_memory_type = DEFAULT_SHARED_MEMORY_TYPE;
+
+shmem_startup_hook_type shmem_startup_hook = NULL;
+
+static Size total_addin_request = 0;
+static bool addin_request_allowed = true;
+
+
+/*
+ * RequestAddinShmemSpace
+ *		Request that extra shmem space be allocated for use by
+ *		a loadable module.
+ *
+ * This is only useful if called from the _PG_init hook of a library that
+ * is loaded into the postmaster via shared_preload_libraries.  Once
+ * shared memory has been allocated, calls will be ignored.  (We could
+ * raise an error, but it seems better to make it a no-op, so that
+ * libraries containing such calls can be reloaded if needed.)
+ */
+void
+RequestAddinShmemSpace(Size size)
+{
+	if (IsUnderPostmaster || !addin_request_allowed)
+		return;					/* too late */
+	total_addin_request = add_size(total_addin_request, size);
+}
+
+
+/*
+ * CreateSharedMemoryAndSemaphores
+ *		Creates and initializes shared memory and semaphores.
+ *
+ * This is called by the postmaster or by a standalone backend.
+ * It is also called by a backend forked from the postmaster in the
+ * EXEC_BACKEND case.  In the latter case, the shared memory segment
+ * already exists and has been physically attached to, but we have to
+ * initialize pointers in local memory that reference the shared structures,
+ * because we didn't inherit the correct pointer values from the postmaster
+ * as we do in the fork() scenario.  The easiest way to do that is to run
+ * through the same code as before.  (Note that the called routines mostly
+ * check IsUnderPostmaster, rather than EXEC_BACKEND, to detect this case.
+ * This is a bit code-wasteful and could be cleaned up.)
+ */
+void
+CreateSharedMemoryAndSemaphores(void)
+{
+	PGShmemHeader *shim = NULL;
+
+	if (!IsUnderPostmaster)
+	{
+		PGShmemHeader *seghdr;
+		Size		size;
+		int			numSemas;
+
+		/* Compute number of semaphores we'll need */
+		numSemas = ProcGlobalSemas();
+		numSemas += SpinlockSemas();
+
+		/*
+		 * Size of the Postgres shared-memory block is estimated via
+		 * moderately-accurate estimates for the big hogs, plus 100K for the
+		 * stuff that's too small to bother with estimating.
+		 *
+		 * We take some care during this phase to ensure that the total size
+		 * request doesn't overflow size_t.  If this gets through, we don't
+		 * need to be so careful during the actual allocation phase.
+		 */
+		size = 100000;
+		size = add_size(size, PGSemaphoreShmemSize(numSemas));
+		size = add_size(size, SpinlockSemaSize());
+		size = add_size(size, hash_estimate_size(SHMEM_INDEX_SIZE,
+												 sizeof(ShmemIndexEnt)));
+		size = add_size(size, BufferShmemSize());
+		size = add_size(size, LockShmemSize());
+		size = add_size(size, PredicateLockShmemSize());
+		size = add_size(size, ProcGlobalShmemSize());
+		size = add_size(size, XLOGShmemSize());
+		size = add_size(size, CLOGShmemSize());
+		size = add_size(size, CommitTsShmemSize());
+		size = add_size(size, SUBTRANSShmemSize());
+		size = add_size(size, TwoPhaseShmemSize());
+		size = add_size(size, BackgroundWorkerShmemSize());
+		size = add_size(size, MultiXactShmemSize());
+		size = add_size(size, LWLockShmemSize());
+		size = add_size(size, ProcArrayShmemSize());
+		size = add_size(size, BackendStatusShmemSize());
+		size = add_size(size, SInvalShmemSize());
+		size = add_size(size, PMSignalShmemSize());
+		size = add_size(size, ProcSignalShmemSize());
+		size = add_size(size, CheckpointerShmemSize());
+		size = add_size(size, AutoVacuumShmemSize());
+		size = add_size(size, ReplicationSlotsShmemSize());
+		size = add_size(size, ReplicationOriginShmemSize());
+		size = add_size(size, WalSndShmemSize());
+		size = add_size(size, WalRcvShmemSize());
+		size = add_size(size, ApplyLauncherShmemSize());
+		size = add_size(size, SnapMgrShmemSize());
+		size = add_size(size, BTreeShmemSize());
+		size = add_size(size, SyncScanShmemSize());
+		size = add_size(size, AsyncShmemSize());
+#ifdef EXEC_BACKEND
+		size = add_size(size, ShmemBackendArraySize());
+#endif
+
+		/* freeze the addin request size and include it */
+		addin_request_allowed = false;
+		size = add_size(size, total_addin_request);
+
+		/* might as well round it off to a multiple of a typical page size */
+		size = add_size(size, 8192 - (size % 8192));
+
+		elog(DEBUG3, "invoking IpcMemoryCreate(size=%zu)", size);
+
+		/*
+		 * Create the shmem segment
+		 */
+		seghdr = PGSharedMemoryCreate(size, &shim);
+
+		InitShmemAccess(seghdr);
+
+		/*
+		 * Create semaphores
+		 */
+		PGReserveSemaphores(numSemas);
+
+		/*
+		 * If spinlocks are disabled, initialize emulation layer (which
+		 * depends on semaphores, so the order is important here).
+		 */
+#ifndef HAVE_SPINLOCKS
+		SpinlockSemaInit();
+#endif
+	}
+	else
+	{
+		/*
+		 * We are reattaching to an existing shared memory segment. This
+		 * should only be reached in the EXEC_BACKEND case.
+		 */
+#ifndef EXEC_BACKEND
+		elog(PANIC, "should be attached to shared memory already");
+#endif
+	}
+
+	/*
+	 * Set up shared memory allocation mechanism
+	 */
+	if (!IsUnderPostmaster)
+		InitShmemAllocation();
+
+	/*
+	 * Now initialize LWLocks, which do shared memory allocation and are
+	 * needed for InitShmemIndex.
+	 */
+	CreateLWLocks();
+
+	/*
+	 * Set up shmem.c index hashtable
+	 */
+	InitShmemIndex();
+
+	/*
+	 * Set up xlog, clog, and buffers
+	 */
+	XLOGShmemInit();
+	CLOGShmemInit();
+	CommitTsShmemInit();
+	SUBTRANSShmemInit();
+	MultiXactShmemInit();
+	InitBufferPool();
+
+	/*
+	 * Set up lock manager
+	 */
+	InitLocks();
+
+	/*
+	 * Set up predicate lock manager
+	 */
+	InitPredicateLocks();
+
+	/*
+	 * Set up process table
+	 */
+	if (!IsUnderPostmaster)
+		InitProcGlobal();
+	CreateSharedProcArray();
+	CreateSharedBackendStatus();
+	TwoPhaseShmemInit();
+	BackgroundWorkerShmemInit();
+
+	/*
+	 * Set up shared-inval messaging
+	 */
+	CreateSharedInvalidationState();
+
+	/*
+	 * Set up interprocess signaling mechanisms
+	 */
+	PMSignalShmemInit();
+	ProcSignalShmemInit();
+	CheckpointerShmemInit();
+	AutoVacuumShmemInit();
+	ReplicationSlotsShmemInit();
+	ReplicationOriginShmemInit();
+	WalSndShmemInit();
+	WalRcvShmemInit();
+	ApplyLauncherShmemInit();
+
+	/*
+	 * Set up other modules that need some shared memory space
+	 */
+	SnapMgrInit();
+	BTreeShmemInit();
+	SyncScanShmemInit();
+	AsyncShmemInit();
+
+#ifdef EXEC_BACKEND
+
+	/*
+	 * Alloc the win32 shared backend array
+	 */
+	if (!IsUnderPostmaster)
+		ShmemBackendArrayAllocation();
+#endif
+
+	/* Initialize dynamic shared memory facilities. */
+	if (!IsUnderPostmaster)
+		dsm_postmaster_startup(shim);
+
+	/*
+	 * Now give loadable modules a chance to set up their shmem allocations
+	 */
+	if (shmem_startup_hook)
+		shmem_startup_hook();
+}