1 /*-------------------------------------------------------------------------
4 * storage manager switch public interface declarations.
7 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
10 * src/include/storage/smgr.h
12 *-------------------------------------------------------------------------
18 #include "storage/block.h"
19 #include "storage/relfilenode.h"
23 * smgr.c maintains a table of SMgrRelation objects, which are essentially
24 * cached file handles. An SMgrRelation is created (if not already present)
25 * by smgropen(), and destroyed by smgrclose(). Note that neither of these
26 * operations imply I/O, they just create or destroy a hashtable entry.
27 * (But smgrclose() may release associated resources, such as OS-level file
30 * An SMgrRelation may have an "owner", which is just a pointer to it from
31 * somewhere else; smgr.c will clear this pointer if the SMgrRelation is
32 * closed. We use this to avoid dangling pointers from relcache to smgr
33 * without having to make the smgr explicitly aware of relcache. There
34 * can't be more than one "owner" pointer per SMgrRelation, but that's
37 * SMgrRelations that do not have an "owner" are considered to be transient,
38 * and are deleted at end of transaction.
40 typedef struct SMgrRelationData
42 /* rnode is the hashtable lookup key, so it must be first! */
43 RelFileNodeBackend smgr_rnode; /* relation physical identifier */
45 /* pointer to owning pointer, or NULL if none */
46 struct SMgrRelationData **smgr_owner;
49 * These next three fields are not actually used or manipulated by smgr,
50 * except that they are reset to InvalidBlockNumber upon a cache flush
51 * event (in particular, upon truncation of the relation). Higher levels
52 * store cached state here so that it will be reset when truncation
53 * happens. In all three cases, InvalidBlockNumber means "unknown".
55 BlockNumber smgr_targblock; /* current insertion target block */
56 BlockNumber smgr_fsm_nblocks; /* last known size of fsm fork */
57 BlockNumber smgr_vm_nblocks; /* last known size of vm fork */
59 /* additional public fields may someday exist here */
62 * Fields below here are intended to be private to smgr.c and its
63 * submodules. Do not touch them from elsewhere.
65 int smgr_which; /* storage manager selector */
67 /* for md.c; NULL for forks that are not open */
68 struct _MdfdVec *md_fd[MAX_FORKNUM + 1];
70 /* if unowned, list link in list of all unowned SMgrRelations */
71 struct SMgrRelationData *next_unowned_reln;
74 typedef SMgrRelationData *SMgrRelation;
76 #define SmgrIsTemp(smgr) \
77 RelFileNodeBackendIsTemp((smgr)->smgr_rnode)
79 extern void smgrinit(void);
80 extern SMgrRelation smgropen(RelFileNode rnode, BackendId backend);
81 extern bool smgrexists(SMgrRelation reln, ForkNumber forknum);
82 extern void smgrsetowner(SMgrRelation *owner, SMgrRelation reln);
83 extern void smgrclose(SMgrRelation reln);
84 extern void smgrcloseall(void);
85 extern void smgrclosenode(RelFileNodeBackend rnode);
86 extern void smgrcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo);
87 extern void smgrdounlink(SMgrRelation reln, bool isRedo);
88 extern void smgrdounlinkfork(SMgrRelation reln, ForkNumber forknum, bool isRedo);
89 extern void smgrextend(SMgrRelation reln, ForkNumber forknum,
90 BlockNumber blocknum, char *buffer, bool skipFsync);
91 extern void smgrprefetch(SMgrRelation reln, ForkNumber forknum,
92 BlockNumber blocknum);
93 extern void smgrread(SMgrRelation reln, ForkNumber forknum,
94 BlockNumber blocknum, char *buffer);
95 extern void smgrwrite(SMgrRelation reln, ForkNumber forknum,
96 BlockNumber blocknum, char *buffer, bool skipFsync);
97 extern BlockNumber smgrnblocks(SMgrRelation reln, ForkNumber forknum);
98 extern void smgrtruncate(SMgrRelation reln, ForkNumber forknum,
100 extern void smgrimmedsync(SMgrRelation reln, ForkNumber forknum);
101 extern void smgrpreckpt(void);
102 extern void smgrsync(void);
103 extern void smgrpostckpt(void);
104 extern void AtEOXact_SMgr(void);
107 /* internals: move me elsewhere -- ay 7/94 */
110 extern void mdinit(void);
111 extern void mdclose(SMgrRelation reln, ForkNumber forknum);
112 extern void mdcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo);
113 extern bool mdexists(SMgrRelation reln, ForkNumber forknum);
114 extern void mdunlink(RelFileNodeBackend rnode, ForkNumber forknum, bool isRedo);
115 extern void mdextend(SMgrRelation reln, ForkNumber forknum,
116 BlockNumber blocknum, char *buffer, bool skipFsync);
117 extern void mdprefetch(SMgrRelation reln, ForkNumber forknum,
118 BlockNumber blocknum);
119 extern void mdread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
121 extern void mdwrite(SMgrRelation reln, ForkNumber forknum,
122 BlockNumber blocknum, char *buffer, bool skipFsync);
123 extern BlockNumber mdnblocks(SMgrRelation reln, ForkNumber forknum);
124 extern void mdtruncate(SMgrRelation reln, ForkNumber forknum,
125 BlockNumber nblocks);
126 extern void mdimmedsync(SMgrRelation reln, ForkNumber forknum);
127 extern void mdpreckpt(void);
128 extern void mdsync(void);
129 extern void mdpostckpt(void);
131 extern void SetForwardFsyncRequests(void);
132 extern void RememberFsyncRequest(RelFileNode rnode, ForkNumber forknum,
134 extern void ForgetRelationFsyncRequests(RelFileNode rnode, ForkNumber forknum);
135 extern void ForgetDatabaseFsyncRequests(Oid dbid);
138 extern Datum smgrout(PG_FUNCTION_ARGS);
139 extern Datum smgrin(PG_FUNCTION_ARGS);
140 extern Datum smgreq(PG_FUNCTION_ARGS);
141 extern Datum smgrne(PG_FUNCTION_ARGS);