1 /*-------------------------------------------------------------------------
4 * shared memory management structures
7 * Copyright (c) 1994, Regents of the University of California
9 * $Id: shmem.h,v 1.20 1999/07/16 17:07:38 momjian Exp $
11 *-------------------------------------------------------------------------
16 #include "storage/spin.h"
17 #include "utils/hsearch.h"
20 /* The shared memory region can start at a different address
21 * in every process. Shared memory "pointers" are actually
22 * offsets relative to the start of the shared memory region(s).
24 typedef unsigned long SHMEM_OFFSET;
26 #define INVALID_OFFSET (-1)
27 #define BAD_LOCATION (-1)
29 /* start of the lowest shared memory region. For now, assume that
30 * there is only one shared memory region
32 extern SHMEM_OFFSET ShmemBase;
35 /* coerce an offset into a pointer in this process's address space */
36 #define MAKE_PTR(xx_offs)\
37 (ShmemBase+((unsigned long)(xx_offs)))
39 /* coerce a pointer into a shmem offset */
40 #define MAKE_OFFSET(xx_ptr)\
41 (SHMEM_OFFSET) (((unsigned long)(xx_ptr))-ShmemBase)
43 #define SHM_PTR_VALID(xx_ptr)\
44 (((unsigned long)xx_ptr) > ShmemBase)
46 /* cannot have an offset to ShmemFreeStart (offset 0) */
47 #define SHM_OFFSET_VALID(xx_offs)\
48 ((xx_offs != 0) && (xx_offs != INVALID_OFFSET))
51 extern SPINLOCK ShmemLock;
52 extern SPINLOCK ShmemIndexLock;
55 typedef struct SHM_QUEUE
62 extern void ShmemIndexReset(void);
63 extern void ShmemCreate(unsigned int key, unsigned int size);
64 extern int InitShmem(unsigned int key, unsigned int size);
65 extern long *ShmemAlloc(unsigned long size);
66 extern int ShmemIsValid(unsigned long addr);
67 extern HTAB *ShmemInitHash(char *name, long init_size, long max_size,
68 HASHCTL *infoP, int hash_flags);
69 extern bool ShmemPIDLookup(int pid, SHMEM_OFFSET *locationPtr);
70 extern SHMEM_OFFSET ShmemPIDDestroy(int pid);
71 extern long *ShmemInitStruct(char *name, unsigned long size,
73 extern bool TransactionIdIsInProgress(TransactionId xid);
74 extern void GetXmaxRecent(TransactionId *XmaxRecent);
79 /* size constants for the shmem index table */
80 /* max size of data structure string name */
81 #define SHMEM_INDEX_KEYSIZE (50)
82 /* data in shmem index table hash bucket */
83 #define SHMEM_INDEX_DATASIZE (sizeof(ShmemIndexEnt) - SHMEM_INDEX_KEYSIZE)
84 /* maximum size of the shmem index table */
85 #define SHMEM_INDEX_SIZE (100)
87 /* this is a hash bucket in the shmem index table */
90 char key[SHMEM_INDEX_KEYSIZE]; /* string name */
91 unsigned long location; /* location in shared mem */
92 unsigned long size; /* numbytes allocated for the structure */
96 * prototypes for functions in shmqueue.c
98 extern void SHMQueueInit(SHM_QUEUE *queue);
99 extern void SHMQueueElemInit(SHM_QUEUE *queue);
100 extern void SHMQueueDelete(SHM_QUEUE *queue);
101 extern void SHMQueueInsertTL(SHM_QUEUE *queue, SHM_QUEUE *elem);
102 extern void SHMQueueFirst(SHM_QUEUE *queue, Pointer *nextPtrPtr,
103 SHM_QUEUE *nextQueue);
104 extern bool SHMQueueEmpty(SHM_QUEUE *queue);