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Diffstat (limited to 'src/include/storage/smgr.h')
| -rw-r--r-- | src/include/storage/smgr.h | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/src/include/storage/smgr.h b/src/include/storage/smgr.h new file mode 100644 index 0000000..6566659 --- /dev/null +++ b/src/include/storage/smgr.h @@ -0,0 +1,109 @@ +/*------------------------------------------------------------------------- + * + * smgr.h + * storage manager switch public interface declarations. + * + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/storage/smgr.h + * + *------------------------------------------------------------------------- + */ +#ifndef SMGR_H +#define SMGR_H + +#include "lib/ilist.h" +#include "storage/block.h" +#include "storage/relfilenode.h" + +/* + * smgr.c maintains a table of SMgrRelation objects, which are essentially + * cached file handles. An SMgrRelation is created (if not already present) + * by smgropen(), and destroyed by smgrclose(). Note that neither of these + * operations imply I/O, they just create or destroy a hashtable entry. + * (But smgrclose() may release associated resources, such as OS-level file + * descriptors.) + * + * An SMgrRelation may have an "owner", which is just a pointer to it from + * somewhere else; smgr.c will clear this pointer if the SMgrRelation is + * closed. We use this to avoid dangling pointers from relcache to smgr + * without having to make the smgr explicitly aware of relcache. There + * can't be more than one "owner" pointer per SMgrRelation, but that's + * all we need. + * + * SMgrRelations that do not have an "owner" are considered to be transient, + * and are deleted at end of transaction. + */ +typedef struct SMgrRelationData +{ + /* rnode is the hashtable lookup key, so it must be first! */ + RelFileNodeBackend smgr_rnode; /* relation physical identifier */ + + /* pointer to owning pointer, or NULL if none */ + struct SMgrRelationData **smgr_owner; + + /* + * These next three fields are not actually used or manipulated by smgr, + * except that they are reset to InvalidBlockNumber upon a cache flush + * event (in particular, upon truncation of the relation). Higher levels + * store cached state here so that it will be reset when truncation + * happens. In all three cases, InvalidBlockNumber means "unknown". + */ + BlockNumber smgr_targblock; /* current insertion target block */ + BlockNumber smgr_fsm_nblocks; /* last known size of fsm fork */ + BlockNumber smgr_vm_nblocks; /* last known size of vm fork */ + + /* additional public fields may someday exist here */ + + /* + * Fields below here are intended to be private to smgr.c and its + * submodules. Do not touch them from elsewhere. + */ + int smgr_which; /* storage manager selector */ + + /* + * for md.c; per-fork arrays of the number of open segments + * (md_num_open_segs) and the segments themselves (md_seg_fds). + */ + int md_num_open_segs[MAX_FORKNUM + 1]; + struct _MdfdVec *md_seg_fds[MAX_FORKNUM + 1]; + + /* if unowned, list link in list of all unowned SMgrRelations */ + dlist_node node; +} SMgrRelationData; + +typedef SMgrRelationData *SMgrRelation; + +#define SmgrIsTemp(smgr) \ + RelFileNodeBackendIsTemp((smgr)->smgr_rnode) + +extern void smgrinit(void); +extern SMgrRelation smgropen(RelFileNode rnode, BackendId backend); +extern bool smgrexists(SMgrRelation reln, ForkNumber forknum); +extern void smgrsetowner(SMgrRelation *owner, SMgrRelation reln); +extern void smgrclearowner(SMgrRelation *owner, SMgrRelation reln); +extern void smgrclose(SMgrRelation reln); +extern void smgrcloseall(void); +extern void smgrclosenode(RelFileNodeBackend rnode); +extern void smgrcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo); +extern void smgrdosyncall(SMgrRelation *rels, int nrels); +extern void smgrdounlinkall(SMgrRelation *rels, int nrels, bool isRedo); +extern void smgrextend(SMgrRelation reln, ForkNumber forknum, + BlockNumber blocknum, char *buffer, bool skipFsync); +extern bool smgrprefetch(SMgrRelation reln, ForkNumber forknum, + BlockNumber blocknum); +extern void smgrread(SMgrRelation reln, ForkNumber forknum, + BlockNumber blocknum, char *buffer); +extern void smgrwrite(SMgrRelation reln, ForkNumber forknum, + BlockNumber blocknum, char *buffer, bool skipFsync); +extern void smgrwriteback(SMgrRelation reln, ForkNumber forknum, + BlockNumber blocknum, BlockNumber nblocks); +extern BlockNumber smgrnblocks(SMgrRelation reln, ForkNumber forknum); +extern void smgrtruncate(SMgrRelation reln, ForkNumber *forknum, + int nforks, BlockNumber *nblocks); +extern void smgrimmedsync(SMgrRelation reln, ForkNumber forknum); +extern void AtEOXact_SMgr(void); + +#endif /* SMGR_H */ |