1 /*-------------------------------------------------------------------------
4 * storage manager switch public interface declarations.
7 * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
10 * src/include/storage/smgr.h
12 *-------------------------------------------------------------------------
17 #include "access/xlog.h"
19 #include "storage/backendid.h"
20 #include "storage/block.h"
21 #include "storage/relfilenode.h"
25 * smgr.c maintains a table of SMgrRelation objects, which are essentially
26 * cached file handles. An SMgrRelation is created (if not already present)
27 * by smgropen(), and destroyed by smgrclose(). Note that neither of these
28 * operations imply I/O, they just create or destroy a hashtable entry.
29 * (But smgrclose() may release associated resources, such as OS-level file
32 * An SMgrRelation may have an "owner", which is just a pointer to it from
33 * somewhere else; smgr.c will clear this pointer if the SMgrRelation is
34 * closed. We use this to avoid dangling pointers from relcache to smgr
35 * without having to make the smgr explicitly aware of relcache. There
36 * can't be more than one "owner" pointer per SMgrRelation, but that's
39 typedef struct SMgrRelationData
41 /* rnode is the hashtable lookup key, so it must be first! */
42 RelFileNodeBackend smgr_rnode; /* relation physical identifier */
44 /* pointer to owning pointer, or NULL if none */
45 struct SMgrRelationData **smgr_owner;
48 * These next three fields are not actually used or manipulated by smgr,
49 * except that they are reset to InvalidBlockNumber upon a cache flush
50 * event (in particular, upon truncation of the relation). Higher levels
51 * store cached state here so that it will be reset when truncation
52 * happens. In all three cases, InvalidBlockNumber means "unknown".
54 BlockNumber smgr_targblock; /* current insertion target block */
55 BlockNumber smgr_fsm_nblocks; /* last known size of fsm fork */
56 BlockNumber smgr_vm_nblocks; /* last known size of vm fork */
58 /* additional public fields may someday exist here */
61 * Fields below here are intended to be private to smgr.c and its
62 * submodules. Do not touch them from elsewhere.
64 int smgr_which; /* storage manager selector */
66 /* for md.c; NULL for forks that are not open */
67 struct _MdfdVec *md_fd[MAX_FORKNUM + 1];
70 typedef SMgrRelationData *SMgrRelation;
72 #define SmgrIsTemp(smgr) \
73 ((smgr)->smgr_rnode.backend != InvalidBackendId)
75 extern void smgrinit(void);
76 extern SMgrRelation smgropen(RelFileNode rnode, BackendId backend);
77 extern bool smgrexists(SMgrRelation reln, ForkNumber forknum);
78 extern void smgrsetowner(SMgrRelation *owner, SMgrRelation reln);
79 extern void smgrclose(SMgrRelation reln);
80 extern void smgrcloseall(void);
81 extern void smgrclosenode(RelFileNodeBackend rnode);
82 extern void smgrcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo);
83 extern void smgrdounlink(SMgrRelation reln, ForkNumber forknum,
85 extern void smgrextend(SMgrRelation reln, ForkNumber forknum,
86 BlockNumber blocknum, char *buffer, bool skipFsync);
87 extern void smgrprefetch(SMgrRelation reln, ForkNumber forknum,
88 BlockNumber blocknum);
89 extern void smgrread(SMgrRelation reln, ForkNumber forknum,
90 BlockNumber blocknum, char *buffer);
91 extern void smgrwrite(SMgrRelation reln, ForkNumber forknum,
92 BlockNumber blocknum, char *buffer, bool skipFsync);
93 extern BlockNumber smgrnblocks(SMgrRelation reln, ForkNumber forknum);
94 extern void smgrtruncate(SMgrRelation reln, ForkNumber forknum,
96 extern void smgrimmedsync(SMgrRelation reln, ForkNumber forknum);
97 extern void smgrpreckpt(void);
98 extern void smgrsync(void);
99 extern void smgrpostckpt(void);
102 /* internals: move me elsewhere -- ay 7/94 */
105 extern void mdinit(void);
106 extern void mdclose(SMgrRelation reln, ForkNumber forknum);
107 extern void mdcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo);
108 extern bool mdexists(SMgrRelation reln, ForkNumber forknum);
109 extern void mdunlink(RelFileNodeBackend rnode, ForkNumber forknum, bool isRedo);
110 extern void mdextend(SMgrRelation reln, ForkNumber forknum,
111 BlockNumber blocknum, char *buffer, bool skipFsync);
112 extern void mdprefetch(SMgrRelation reln, ForkNumber forknum,
113 BlockNumber blocknum);
114 extern void mdread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
116 extern void mdwrite(SMgrRelation reln, ForkNumber forknum,
117 BlockNumber blocknum, char *buffer, bool skipFsync);
118 extern BlockNumber mdnblocks(SMgrRelation reln, ForkNumber forknum);
119 extern void mdtruncate(SMgrRelation reln, ForkNumber forknum,
120 BlockNumber nblocks);
121 extern void mdimmedsync(SMgrRelation reln, ForkNumber forknum);
122 extern void mdpreckpt(void);
123 extern void mdsync(void);
124 extern void mdpostckpt(void);
126 extern void SetForwardFsyncRequests(void);
127 extern void RememberFsyncRequest(RelFileNodeBackend rnode, ForkNumber forknum,
129 extern void ForgetRelationFsyncRequests(RelFileNodeBackend rnode,
131 extern void ForgetDatabaseFsyncRequests(Oid dbid);
134 extern Datum smgrout(PG_FUNCTION_ARGS);
135 extern Datum smgrin(PG_FUNCTION_ARGS);
136 extern Datum smgreq(PG_FUNCTION_ARGS);
137 extern Datum smgrne(PG_FUNCTION_ARGS);