diff options
Diffstat (limited to 'src/include/utils/rel.h')
| -rw-r--r-- | src/include/utils/rel.h | 37 |
1 files changed, 24 insertions, 13 deletions
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h index 77d176a9348..b4faa1c1238 100644 --- a/src/include/utils/rel.h +++ b/src/include/utils/rel.h @@ -24,6 +24,7 @@ #include "rewrite/prs2lock.h" #include "storage/block.h" #include "storage/relfilenode.h" +#include "storage/smgr.h" #include "utils/relcache.h" #include "utils/reltrigger.h" @@ -53,8 +54,7 @@ typedef LockInfoData *LockInfo; typedef struct RelationData { RelFileNode rd_node; /* relation physical identifier */ - /* use "struct" here to avoid needing to include smgr.h: */ - struct SMgrRelationData *rd_smgr; /* cached file handle, or NULL */ + SMgrRelation rd_smgr; /* cached file handle, or NULL */ int rd_refcnt; /* reference count */ BackendId rd_backend; /* owning backend id, if temporary relation */ bool rd_islocaltemp; /* rel is a temp rel of this session */ @@ -528,14 +528,25 @@ typedef struct ViewOptions ((relation)->rd_rel->relfilenode == InvalidOid)) /* - * RelationOpenSmgr - * Open the relation at the smgr level, if not already done. - */ -#define RelationOpenSmgr(relation) \ - do { \ - if ((relation)->rd_smgr == NULL) \ - smgrsetowner(&((relation)->rd_smgr), smgropen((relation)->rd_node, (relation)->rd_backend)); \ - } while (0) + * RelationGetSmgr + * Returns smgr file handle for a relation, opening it if needed. + * + * Very little code is authorized to touch rel->rd_smgr directly. Instead + * use this function to fetch its value. + * + * Note: since a relcache flush can cause the file handle to be closed again, + * it's unwise to hold onto the pointer returned by this function for any + * long period. Recommended practice is to just re-execute RelationGetSmgr + * each time you need to access the SMgrRelation. It's quite cheap in + * comparison to whatever an smgr function is going to do. + */ +static inline SMgrRelation +RelationGetSmgr(Relation rel) +{ + if (unlikely(rel->rd_smgr == NULL)) + smgrsetowner(&(rel->rd_smgr), smgropen(rel->rd_node, rel->rd_backend)); + return rel->rd_smgr; +} /* * RelationCloseSmgr @@ -557,7 +568,8 @@ typedef struct ViewOptions * Fetch relation's current insertion target block. * * Returns InvalidBlockNumber if there is no current target block. Note - * that the target block status is discarded on any smgr-level invalidation. + * that the target block status is discarded on any smgr-level invalidation, + * so there's no need to re-open the smgr handle if it's not currently open. */ #define RelationGetTargetBlock(relation) \ ( (relation)->rd_smgr != NULL ? (relation)->rd_smgr->smgr_targblock : InvalidBlockNumber ) @@ -568,8 +580,7 @@ typedef struct ViewOptions */ #define RelationSetTargetBlock(relation, targblock) \ do { \ - RelationOpenSmgr(relation); \ - (relation)->rd_smgr->smgr_targblock = (targblock); \ + RelationGetSmgr(relation)->smgr_targblock = (targblock); \ } while (0) /* |