init

db_include/storage/shmem.h

@@ -0,0 +1,81 @@
+/*-------------------------------------------------------------------------
+ *
+ * shmem.h
+ *	  shared memory management structures
+ *
+ * Historical note:
+ * A long time ago, Postgres' shared memory region was allowed to be mapped
+ * at a different address in each process, and shared memory "pointers" were
+ * passed around as offsets relative to the start of the shared memory region.
+ * That is no longer the case: each process must map the shared memory region
+ * at the same address.  This means shared memory pointers can be passed
+ * around directly between different processes.
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/shmem.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef SHMEM_H
+#define SHMEM_H
+
+#include "utils/hsearch.h"
+
+
+/* shmqueue.c */
+typedef struct SHM_QUEUE
+{
+	struct SHM_QUEUE *prev;
+	struct SHM_QUEUE *next;
+} SHM_QUEUE;
+
+/* shmem.c */
+extern void InitShmemAccess(void *seghdr);
+extern void InitShmemAllocation(void);
+extern void *ShmemAlloc(Size size);
+extern void *ShmemAllocNoError(Size size);
+extern void *ShmemAllocUnlocked(Size size);
+extern bool ShmemAddrIsValid(const void *addr);
+extern void InitShmemIndex(void);
+extern HTAB *ShmemInitHash(const char *name, long init_size, long max_size,
+						   HASHCTL *infoP, int hash_flags);
+extern void *ShmemInitStruct(const char *name, Size size, bool *foundPtr);
+extern Size add_size(Size s1, Size s2);
+extern Size mul_size(Size s1, Size s2);
+
+/* ipci.c */
+extern void RequestAddinShmemSpace(Size size);
+
+/* size constants for the shmem index table */
+ /* max size of data structure string name */
+#define SHMEM_INDEX_KEYSIZE		 (48)
+ /* estimated size of the shmem index table (not a hard limit) */
+#define SHMEM_INDEX_SIZE		 (64)
+
+/* this is a hash bucket in the shmem index table */
+typedef struct
+{
+	char		key[SHMEM_INDEX_KEYSIZE];	/* string name */
+	void	   *location;		/* location in shared mem */
+	Size		size;			/* # bytes requested for the structure */
+	Size		allocated_size; /* # bytes actually allocated */
+} ShmemIndexEnt;
+
+/*
+ * prototypes for functions in shmqueue.c
+ */
+extern void SHMQueueInit(SHM_QUEUE *queue);
+extern void SHMQueueElemInit(SHM_QUEUE *queue);
+extern void SHMQueueDelete(SHM_QUEUE *queue);
+extern void SHMQueueInsertBefore(SHM_QUEUE *queue, SHM_QUEUE *elem);
+extern void SHMQueueInsertAfter(SHM_QUEUE *queue, SHM_QUEUE *elem);
+extern Pointer SHMQueueNext(const SHM_QUEUE *queue, const SHM_QUEUE *curElem,
+							Size linkOffset);
+extern Pointer SHMQueuePrev(const SHM_QUEUE *queue, const SHM_QUEUE *curElem,
+							Size linkOffset);
+extern bool SHMQueueEmpty(const SHM_QUEUE *queue);
+extern bool SHMQueueIsDetached(const SHM_QUEUE *queue);
+
+#endif							/* SHMEM_H */