/*
* Update index metapage's lastUsedPages info from local cache, if possible
*
* Updating meta page isn't critical for index working, so
* 1 use ConditionalLockBuffer to improve concurrency
* 2 don't WAL-log metabuffer changes to decrease WAL traffic
*/
void
SpGistUpdateMetaPage(Relation index)
{
SpGistCache *cache = (SpGistCache *) index->rd_amcache;
if (cache != NULL)
{
Buffer metabuffer;
SpGistMetaPageData *metadata;
metabuffer = ReadBuffer(index, SPGIST_METAPAGE_BLKNO);
if (ConditionalLockBuffer(metabuffer))
{
metadata = SpGistPageGetMeta(BufferGetPage(metabuffer));
metadata->lastUsedPages = cache->lastUsedPages;
MarkBufferDirty(metabuffer);
UnlockReleaseBuffer(metabuffer);
}
else
{
ReleaseBuffer(metabuffer);
}
}
}
void
SpGistInitMetabuffer(Buffer b, Relation index)
{
SpGistMetaPageData *metadata;
Page page = BufferGetPage(b);
SpGistInitPage(page, SPGIST_META, BufferGetPageSize(b));
metadata = SpGistPageGetMeta(page);
memset(metadata, 0, sizeof(SpGistMetaPageData));
metadata->magickNumber = SPGIST_MAGICK_NUMBER;
}
/*
* Initialize metadata page
*/
void
SpGistInitMetapage(Page page)
{
SpGistMetaPageData *metadata;
int i;
SpGistInitPage(page, SPGIST_META);
metadata = SpGistPageGetMeta(page);
memset(metadata, 0, sizeof(SpGistMetaPageData));
metadata->magicNumber = SPGIST_MAGIC_NUMBER;
/* initialize last-used-page cache to empty */
for (i = 0; i < SPGIST_CACHED_PAGES; i++)
metadata->lastUsedPages.cachedPage[i].blkno = InvalidBlockNumber;
}
/*
* Initialize metadata page
*/
void
SpGistInitMetapage(Page page)
{
SpGistMetaPageData *metadata;
SpGistInitPage(page, SPGIST_META);
metadata = SpGistPageGetMeta(page);
memset(metadata, 0, sizeof(SpGistMetaPageData));
metadata->magicNumber = SPGIST_MAGIC_NUMBER;
/* initialize last-used-page cache to empty */
metadata->lastUsedPages.innerPage[0].blkno = InvalidBlockNumber;
metadata->lastUsedPages.innerPage[1].blkno = InvalidBlockNumber;
metadata->lastUsedPages.innerPage[2].blkno = InvalidBlockNumber;
metadata->lastUsedPages.leafPage.blkno = InvalidBlockNumber;
}
/*
* Fetch local cache of AM-specific info about the index, initializing it
* if necessary
*/
SpGistCache *
spgGetCache(Relation index)
{
SpGistCache *cache;
if (index->rd_amcache == NULL)
{
Oid atttype;
spgConfigIn in;
FmgrInfo *procinfo;
Buffer metabuffer;
SpGistMetaPageData *metadata;
cache = MemoryContextAllocZero(index->rd_indexcxt,
sizeof(SpGistCache));
/* SPGiST doesn't support multi-column indexes */
Assert(index->rd_att->natts == 1);
/*
* Get the actual data type of the indexed column from the index
* tupdesc. We pass this to the opclass config function so that
* polymorphic opclasses are possible.
*/
atttype = index->rd_att->attrs[0]->atttypid;
/* Call the config function to get config info for the opclass */
in.attType = atttype;
procinfo = index_getprocinfo(index, 1, SPGIST_CONFIG_PROC);
FunctionCall2Coll(procinfo,
index->rd_indcollation[0],
PointerGetDatum(&in),
PointerGetDatum(&cache->config));
/* Get the information we need about each relevant datatype */
fillTypeDesc(&cache->attType, atttype);
fillTypeDesc(&cache->attPrefixType, cache->config.prefixType);
fillTypeDesc(&cache->attLabelType, cache->config.labelType);
/* Last, get the lastUsedPages data from the metapage */
metabuffer = ReadBuffer(index, SPGIST_METAPAGE_BLKNO);
LockBuffer(metabuffer, BUFFER_LOCK_SHARE);
metadata = SpGistPageGetMeta(BufferGetPage(metabuffer));
if (metadata->magicNumber != SPGIST_MAGIC_NUMBER)
elog(ERROR, "index \"%s\" is not an SP-GiST index",
RelationGetRelationName(index));
cache->lastUsedPages = metadata->lastUsedPages;
UnlockReleaseBuffer(metabuffer);
index->rd_amcache = (void *) cache;
}
else
{
/* assume it's up to date */
cache = (SpGistCache *) index->rd_amcache;
}
return cache;
}