diff options
| -rw-r--r-- | src/backend/storage/smgr/md.c | 8 | ||||
| -rw-r--r-- | src/backend/storage/smgr/smgr.c | 74 | ||||
| -rw-r--r-- | src/include/storage/smgr.h | 3 |
3 files changed, 20 insertions, 65 deletions
diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c index f28a3e6d066..58a6e0f4ddc 100644 --- a/src/backend/storage/smgr/md.c +++ b/src/backend/storage/smgr/md.c @@ -1681,13 +1681,7 @@ DropRelationFiles(RelFileNode *delrels, int ndelrels, bool isRedo) smgrdounlinkall(srels, ndelrels, isRedo); - /* - * Call smgrclose() in reverse order as when smgropen() is called. - * This trick enables remove_from_unowned_list() in smgrclose() - * to search the SMgrRelation from the unowned list, - * with O(1) performance. - */ - for (i = ndelrels - 1; i >= 0; i--) + for (i = 0; i < ndelrels; i++) smgrclose(srels[i]); pfree(srels); } diff --git a/src/backend/storage/smgr/smgr.c b/src/backend/storage/smgr/smgr.c index 244b4ea72c8..c3da4277418 100644 --- a/src/backend/storage/smgr/smgr.c +++ b/src/backend/storage/smgr/smgr.c @@ -18,6 +18,7 @@ #include "postgres.h" #include "commands/tablespace.h" +#include "lib/ilist.h" #include "storage/bufmgr.h" #include "storage/ipc.h" #include "storage/smgr.h" @@ -80,12 +81,10 @@ static const int NSmgr = lengthof(smgrsw); */ static HTAB *SMgrRelationHash = NULL; -static SMgrRelation first_unowned_reln = NULL; +static dlist_head unowned_relns; /* local function prototypes */ static void smgrshutdown(int code, Datum arg); -static void add_to_unowned_list(SMgrRelation reln); -static void remove_from_unowned_list(SMgrRelation reln); /* @@ -148,7 +147,7 @@ smgropen(RelFileNode rnode, BackendId backend) ctl.entrysize = sizeof(SMgrRelationData); SMgrRelationHash = hash_create("smgr relation table", 400, &ctl, HASH_ELEM | HASH_BLOBS); - first_unowned_reln = NULL; + dlist_init(&unowned_relns); } /* Look up or create an entry */ @@ -175,7 +174,7 @@ smgropen(RelFileNode rnode, BackendId backend) reln->md_fd[forknum] = NULL; /* it has no owner yet */ - add_to_unowned_list(reln); + dlist_push_tail(&unowned_relns, &reln->node); } return reln; @@ -205,7 +204,7 @@ smgrsetowner(SMgrRelation *owner, SMgrRelation reln) if (reln->smgr_owner) *(reln->smgr_owner) = NULL; else - remove_from_unowned_list(reln); + dlist_delete(&reln->node); /* Now establish the ownership relationship. */ reln->smgr_owner = owner; @@ -229,53 +228,8 @@ smgrclearowner(SMgrRelation *owner, SMgrRelation reln) /* unset our reference to the owner */ reln->smgr_owner = NULL; - add_to_unowned_list(reln); -} - -/* - * add_to_unowned_list -- link an SMgrRelation onto the unowned list - * - * Check remove_from_unowned_list()'s comments for performance - * considerations. - */ -static void -add_to_unowned_list(SMgrRelation reln) -{ - /* place it at head of the list (to make smgrsetowner cheap) */ - reln->next_unowned_reln = first_unowned_reln; - first_unowned_reln = reln; -} - -/* - * remove_from_unowned_list -- unlink an SMgrRelation from the unowned list - * - * If the reln is not present in the list, nothing happens. Typically this - * would be caller error, but there seems no reason to throw an error. - * - * In the worst case this could be rather slow; but in all the cases that seem - * likely to be performance-critical, the reln being sought will actually be - * first in the list. Furthermore, the number of unowned relns touched in any - * one transaction shouldn't be all that high typically. So it doesn't seem - * worth expending the additional space and management logic needed for a - * doubly-linked list. - */ -static void -remove_from_unowned_list(SMgrRelation reln) -{ - SMgrRelation *link; - SMgrRelation cur; - - for (link = &first_unowned_reln, cur = *link; - cur != NULL; - link = &cur->next_unowned_reln, cur = *link) - { - if (cur == reln) - { - *link = cur->next_unowned_reln; - cur->next_unowned_reln = NULL; - break; - } - } + /* add to list of unowned relations */ + dlist_push_tail(&unowned_relns, &reln->node); } /* @@ -302,7 +256,7 @@ smgrclose(SMgrRelation reln) owner = reln->smgr_owner; if (!owner) - remove_from_unowned_list(reln); + dlist_delete(&reln->node); if (hash_search(SMgrRelationHash, (void *) &(reln->smgr_rnode), @@ -782,13 +736,19 @@ smgrpostckpt(void) void AtEOXact_SMgr(void) { + dlist_mutable_iter iter; + /* * Zap all unowned SMgrRelations. We rely on smgrclose() to remove each * one from the list. */ - while (first_unowned_reln != NULL) + dlist_foreach_modify(iter, &unowned_relns) { - Assert(first_unowned_reln->smgr_owner == NULL); - smgrclose(first_unowned_reln); + SMgrRelation rel = dlist_container(SMgrRelationData, node, + iter.cur); + + Assert(rel->smgr_owner == NULL); + + smgrclose(rel); } } diff --git a/src/include/storage/smgr.h b/src/include/storage/smgr.h index dfb7e98e932..35c78ef6f25 100644 --- a/src/include/storage/smgr.h +++ b/src/include/storage/smgr.h @@ -15,6 +15,7 @@ #define SMGR_H #include "fmgr.h" +#include "lib/ilist.h" #include "storage/block.h" #include "storage/relfilenode.h" @@ -68,7 +69,7 @@ typedef struct SMgrRelationData struct _MdfdVec *md_fd[MAX_FORKNUM + 1]; /* if unowned, list link in list of all unowned SMgrRelations */ - struct SMgrRelationData *next_unowned_reln; + dlist_node node; } SMgrRelationData; typedef SMgrRelationData *SMgrRelation; |