/*
* smgrtruncate() -- Truncate supplied relation to the specified number
* of blocks
*
* The truncation is done immediately, so this can't be rolled back.
*/
void
smgrtruncate(SMgrRelation reln, ForkNumber forknum, BlockNumber nblocks)
{
/*
* Get rid of any buffers for the about-to-be-deleted blocks. bufmgr will
* just drop them without bothering to write the contents.
*/
DropRelFileNodeBuffers(reln->smgr_rnode, forknum, nblocks);
/*
* Send a shared-inval message to force other backends to close any smgr
* references they may have for this rel. This is useful because they
* might have open file pointers to segments that got removed, and/or
* smgr_targblock variables pointing past the new rel end. (The inval
* message will come back to our backend, too, causing a
* probably-unnecessary local smgr flush. But we don't expect that this
* is a performance-critical path.) As in the unlink code, we want to be
* sure the message is sent before we start changing things on-disk.
*/
CacheInvalidateSmgr(reln->smgr_rnode);
/*
* Do the truncation.
*/
(*(smgrsw[reln->smgr_which].smgr_truncate)) (reln, forknum, nblocks);
}
/*
* Ensure that the visibility map fork is at least vm_nblocks long, extending
* it if necessary with zeroed pages.
*/
static void
vm_extend(Relation rel, BlockNumber vm_nblocks)
{
BlockNumber vm_nblocks_now;
Page pg;
pg = (Page) palloc(BLCKSZ);
PageInit(pg, BLCKSZ, 0);
/*
* We use the relation extension lock to lock out other backends trying to
* extend the visibility map at the same time. It also locks out extension
* of the main fork, unnecessarily, but extending the visibility map
* happens seldom enough that it doesn't seem worthwhile to have a
* separate lock tag type for it.
*
* Note that another backend might have extended or created the relation
* by the time we get the lock.
*/
LockRelationForExtension(rel, ExclusiveLock);
/* Might have to re-open if a cache flush happened */
RelationOpenSmgr(rel);
/*
* Create the file first if it doesn't exist. If smgr_vm_nblocks is
* positive then it must exist, no need for an smgrexists call.
*/
if ((rel->rd_smgr->smgr_vm_nblocks == 0 ||
rel->rd_smgr->smgr_vm_nblocks == InvalidBlockNumber) &&
!smgrexists(rel->rd_smgr, VISIBILITYMAP_FORKNUM))
smgrcreate(rel->rd_smgr, VISIBILITYMAP_FORKNUM, false);
vm_nblocks_now = smgrnblocks(rel->rd_smgr, VISIBILITYMAP_FORKNUM);
/* Now extend the file */
while (vm_nblocks_now < vm_nblocks)
{
smgrextend(rel->rd_smgr, VISIBILITYMAP_FORKNUM, vm_nblocks_now,
(char *) pg, false);
vm_nblocks_now++;
}
/*
* Send a shared-inval message to force other backends to close any smgr
* references they may have for this rel, which we are about to change.
* This is a useful optimization because it means that backends don't have
* to keep checking for creation or extension of the file, which happens
* infrequently.
*/
CacheInvalidateSmgr(rel->rd_smgr->smgr_rnode);
/* Update local cache with the up-to-date size */
rel->rd_smgr->smgr_vm_nblocks = vm_nblocks_now;
UnlockRelationForExtension(rel, ExclusiveLock);
pfree(pg);
}
/*
* smgrdounlink() -- Immediately unlink all forks of a relation.
*
* All forks of the relation are removed from the store. This should
* not be used during transactional operations, since it can't be undone.
*
* If isRedo is true, it is okay for the underlying file(s) to be gone
* already.
*
* This is equivalent to calling smgrdounlinkfork for each fork, but
* it's significantly quicker so should be preferred when possible.
*/
void
smgrdounlink(SMgrRelation reln, bool isRedo)
{
RelFileNodeBackend rnode = reln->smgr_rnode;
int which = reln->smgr_which;
ForkNumber forknum;
/* Close the forks at smgr level */
for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
(*(smgrsw[which].smgr_close)) (reln, forknum);
/*
* Get rid of any remaining buffers for the relation. bufmgr will just
* drop them without bothering to write the contents.
*/
DropRelFileNodesAllBuffers(&rnode, 1);
/*
* It'd be nice to tell the stats collector to forget it immediately, too.
* But we can't because we don't know the OID (and in cases involving
* relfilenode swaps, it's not always clear which table OID to forget,
* anyway).
*/
/*
* Send a shared-inval message to force other backends to close any
* dangling smgr references they may have for this rel. We should do this
* before starting the actual unlinking, in case we fail partway through
* that step. Note that the sinval message will eventually come back to
* this backend, too, and thereby provide a backstop that we closed our
* own smgr rel.
*/
CacheInvalidateSmgr(rnode);
/*
* Delete the physical file(s).
*
* Note: smgr_unlink must treat deletion failure as a WARNING, not an
* ERROR, because we've already decided to commit or abort the current
* xact.
*/
(*(smgrsw[which].smgr_unlink)) (rnode, InvalidForkNumber, isRedo);
}
/*
* smgrdounlinkall() -- Immediately unlink all forks of all given relations
*
* All forks of all given relations are removed from the store. This
* should not be used during transactional operations, since it can't be
* undone.
*
* If isRedo is true, it is okay for the underlying file(s) to be gone
* already.
*
* This is equivalent to calling smgrdounlink for each relation, but it's
* significantly quicker so should be preferred when possible.
*/
void
smgrdounlinkall(SMgrRelation *rels, int nrels, bool isRedo)
{
int i = 0;
RelFileNodeBackend *rnodes;
ForkNumber forknum;
if (nrels == 0)
return;
/*
* create an array which contains all relations to be dropped, and
* close each relation's forks at the smgr level while at it
*/
rnodes = palloc(sizeof(RelFileNodeBackend) * nrels);
for (i = 0; i < nrels; i++)
{
RelFileNodeBackend rnode = rels[i]->smgr_rnode;
int which = rels[i]->smgr_which;
rnodes[i] = rnode;
/* Close the forks at smgr level */
for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
(*(smgrsw[which].smgr_close)) (rels[i], forknum);
}
/*
* Get rid of any remaining buffers for the relations. bufmgr will just
* drop them without bothering to write the contents.
*/
DropRelFileNodesAllBuffers(rnodes, nrels);
/*
* It'd be nice to tell the stats collector to forget them immediately, too.
* But we can't because we don't know the OIDs.
*/
/*
* Send a shared-inval message to force other backends to close any
* dangling smgr references they may have for these rels. We should do
* this before starting the actual unlinking, in case we fail partway
* through that step. Note that the sinval messages will eventually come
* back to this backend, too, and thereby provide a backstop that we closed
* our own smgr rel.
*/
for (i = 0; i < nrels; i++)
CacheInvalidateSmgr(rnodes[i]);
/*
* Delete the physical file(s).
*
* Note: smgr_unlink must treat deletion failure as a WARNING, not an
* ERROR, because we've already decided to commit or abort the current
* xact.
*/
for (i = 0; i < nrels; i++)
{
int which = rels[i]->smgr_which;
for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
(*(smgrsw[which].smgr_unlink)) (rnodes[i], forknum, isRedo);
}
pfree(rnodes);
}
