ts_cache.c

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/*-------------------------------------------------------------------------
 *
 * ts_cache.c
 *	  Tsearch related object caches.
 *
 * Tsearch performance is very sensitive to performance of parsers,
 * dictionaries and mapping, so lookups should be cached as much
 * as possible.
 *
 * Once a backend has created a cache entry for a particular TS object OID,
 * the cache entry will exist for the life of the backend; hence it is
 * safe to hold onto a pointer to the cache entry while doing things that
 * might result in recognizing a cache invalidation.  Beware however that
 * subsidiary information might be deleted and reallocated somewhere else
 * if a cache inval and reval happens!	This does not look like it will be
 * a big problem as long as parser and dictionary methods do not attempt
 * any database access.
 *
 *
 * Copyright (c) 2006-2008, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/backend/utils/cache/ts_cache.c,v 1.5 2008/01/01 19:45:53 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/heapam.h"
#include "access/xact.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/pg_ts_config.h"
#include "catalog/pg_ts_config_map.h"
#include "catalog/pg_ts_dict.h"
#include "catalog/pg_ts_parser.h"
#include "catalog/pg_ts_template.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "miscadmin.h"
#include "tsearch/ts_cache.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/catcache.h"
#include "utils/fmgroids.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/syscache.h"


/*
 * MAXTOKENTYPE/MAXDICTSPERTT are arbitrary limits on the workspace size
 * used in lookup_ts_config_cache().  We could avoid hardwiring a limit
 * by making the workspace dynamically enlargeable, but it seems unlikely
 * to be worth the trouble.
 */
#define MAXTOKENTYPE	256
#define MAXDICTSPERTT	100


static HTAB *TSParserCacheHash = NULL;
static TSParserCacheEntry *lastUsedParser = NULL;

static HTAB *TSDictionaryCacheHash = NULL;
static TSDictionaryCacheEntry *lastUsedDictionary = NULL;

static HTAB *TSConfigCacheHash = NULL;
static TSConfigCacheEntry *lastUsedConfig = NULL;

/*
 * GUC default_text_search_config, and a cache of the current config's OID
 */
char	   *TSCurrentConfig = NULL;

static Oid	TSCurrentConfigCache = InvalidOid;


/*
 * We use this catcache callback to detect when a visible change to a TS
 * catalog entry has been made, by either our own backend or another one.
 * We don't get enough information to know *which* specific catalog row
 * changed, so we have to invalidate all related cache entries.  Fortunately,
 * it seems unlikely that TS configuration changes will occur often enough
 * for this to be a performance problem.
 *
 * We can use the same function for all TS caches by passing the hash
 * table address as the "arg".
 */
static void
InvalidateTSCacheCallBack(Datum arg, Oid relid)
{
	HTAB	   *hash = (HTAB *) DatumGetPointer(arg);
	HASH_SEQ_STATUS status;
	TSAnyCacheEntry *entry;

	hash_seq_init(&status, hash);
	while ((entry = (TSAnyCacheEntry *) hash_seq_search(&status)) != NULL)
		entry->isvalid = false;

	/* Also invalidate the current-config cache if it's pg_ts_config */
	if (hash == TSConfigCacheHash)
		TSCurrentConfigCache = InvalidOid;
}

/*
 * Fetch parser cache entry
 */
TSParserCacheEntry *
lookup_ts_parser_cache(Oid prsId)
{
	TSParserCacheEntry *entry;

	if (TSParserCacheHash == NULL)
	{
		/* First time through: initialize the hash table */
		HASHCTL		ctl;

		if (!CacheMemoryContext)
			CreateCacheMemoryContext();

		MemSet(&ctl, 0, sizeof(ctl));
		ctl.keysize = sizeof(Oid);
		ctl.entrysize = sizeof(TSParserCacheEntry);
		ctl.hash = oid_hash;
		TSParserCacheHash = hash_create("Tsearch parser cache", 4,
										&ctl, HASH_ELEM | HASH_FUNCTION);
		/* Flush cache on pg_ts_parser changes */
		CacheRegisterSyscacheCallback(TSPARSEROID, InvalidateTSCacheCallBack,
									  PointerGetDatum(TSParserCacheHash));
	}

	/* Check single-entry cache */
	if (lastUsedParser && lastUsedParser->prsId == prsId &&
		lastUsedParser->isvalid)
		return lastUsedParser;

	/* Try to look up an existing entry */
	entry = (TSParserCacheEntry *) hash_search(TSParserCacheHash,
											   (void *) &prsId,
											   HASH_FIND, NULL);
	if (entry == NULL || !entry->isvalid)
	{
		/*
		 * If we didn't find one, we want to make one. But first look up the
		 * object to be sure the OID is real.
		 */
		HeapTuple	tp;
		Form_pg_ts_parser prs;

		tp = SearchSysCache(TSPARSEROID,
							ObjectIdGetDatum(prsId),
							0, 0, 0);
		if (!HeapTupleIsValid(tp))
			elog(ERROR, "cache lookup failed for text search parser %u",
				 prsId);
		prs = (Form_pg_ts_parser) GETSTRUCT(tp);

		/*
		 * Sanity checks
		 */
		if (!OidIsValid(prs->prsstart))
			elog(ERROR, "text search parser %u has no prsstart method", prsId);
		if (!OidIsValid(prs->prstoken))
			elog(ERROR, "text search parser %u has no prstoken method", prsId);
		if (!OidIsValid(prs->prsend))
			elog(ERROR, "text search parser %u has no prsend method", prsId);

		if (entry == NULL)
		{
			bool		found;

			/* Now make the cache entry */
			entry = (TSParserCacheEntry *)
				hash_search(TSParserCacheHash,
							(void *) &prsId,
							HASH_ENTER, &found);
			Assert(!found);		/* it wasn't there a moment ago */
		}

		MemSet(entry, 0, sizeof(TSParserCacheEntry));
		entry->prsId = prsId;
		entry->startOid = prs->prsstart;
		entry->tokenOid = prs->prstoken;
		entry->endOid = prs->prsend;
		entry->headlineOid = prs->prsheadline;
		entry->lextypeOid = prs->prslextype;

		ReleaseSysCache(tp);

		fmgr_info_cxt(entry->startOid, &entry->prsstart, CacheMemoryContext);
		fmgr_info_cxt(entry->tokenOid, &entry->prstoken, CacheMemoryContext);
		fmgr_info_cxt(entry->endOid, &entry->prsend, CacheMemoryContext);
		if (OidIsValid(entry->headlineOid))
			fmgr_info_cxt(entry->headlineOid, &entry->prsheadline,
						  CacheMemoryContext);

		entry->isvalid = true;
	}

	lastUsedParser = entry;

	return entry;
}

/*
 * Fetch dictionary cache entry
 */
TSDictionaryCacheEntry *
lookup_ts_dictionary_cache(Oid dictId)
{
	TSDictionaryCacheEntry *entry;

	if (TSDictionaryCacheHash == NULL)
	{
		/* First time through: initialize the hash table */
		HASHCTL		ctl;

		if (!CacheMemoryContext)
			CreateCacheMemoryContext();

		MemSet(&ctl, 0, sizeof(ctl));
		ctl.keysize = sizeof(Oid);
		ctl.entrysize = sizeof(TSDictionaryCacheEntry);
		ctl.hash = oid_hash;
		TSDictionaryCacheHash = hash_create("Tsearch dictionary cache", 8,
											&ctl, HASH_ELEM | HASH_FUNCTION);
		/* Flush cache on pg_ts_dict and pg_ts_template changes */
		CacheRegisterSyscacheCallback(TSDICTOID, InvalidateTSCacheCallBack,
									  PointerGetDatum(TSDictionaryCacheHash));
		CacheRegisterSyscacheCallback(TSTEMPLATEOID, InvalidateTSCacheCallBack,
									  PointerGetDatum(TSDictionaryCacheHash));
	}

	/* Check single-entry cache */
	if (lastUsedDictionary && lastUsedDictionary->dictId == dictId &&
		lastUsedDictionary->isvalid)
		return lastUsedDictionary;

	/* Try to look up an existing entry */
	entry = (TSDictionaryCacheEntry *) hash_search(TSDictionaryCacheHash,
												   (void *) &dictId,
												   HASH_FIND, NULL);
	if (entry == NULL || !entry->isvalid)
	{
		/*
		 * If we didn't find one, we want to make one. But first look up the
		 * object to be sure the OID is real.
		 */
		HeapTuple	tpdict,
					tptmpl;
		Form_pg_ts_dict dict;
		Form_pg_ts_template template;
		MemoryContext saveCtx;

		tpdict = SearchSysCache(TSDICTOID,
								ObjectIdGetDatum(dictId),
								0, 0, 0);
		if (!HeapTupleIsValid(tpdict))
			elog(ERROR, "cache lookup failed for text search dictionary %u",
				 dictId);
		dict = (Form_pg_ts_dict) GETSTRUCT(tpdict);

		/*
		 * Sanity checks
		 */
		if (!OidIsValid(dict->dicttemplate))
			elog(ERROR, "text search dictionary %u has no template", dictId);

		/*
		 * Retrieve dictionary's template
		 */
		tptmpl = SearchSysCache(TSTEMPLATEOID,
								ObjectIdGetDatum(dict->dicttemplate),
								0, 0, 0);
		if (!HeapTupleIsValid(tptmpl))
			elog(ERROR, "cache lookup failed for text search template %u",
				 dict->dicttemplate);
		template = (Form_pg_ts_template) GETSTRUCT(tptmpl);

		/*
		 * Sanity checks
		 */
		if (!OidIsValid(template->tmpllexize))
			elog(ERROR, "text search template %u has no lexize method",
				 template->tmpllexize);

		if (entry == NULL)
		{
			bool		found;

			/* Now make the cache entry */
			entry = (TSDictionaryCacheEntry *)
				hash_search(TSDictionaryCacheHash,
							(void *) &dictId,
							HASH_ENTER, &found);
			Assert(!found);		/* it wasn't there a moment ago */

			/* Create private memory context the first time through */
			saveCtx = AllocSetContextCreate(CacheMemoryContext,
											NameStr(dict->dictname),
											ALLOCSET_SMALL_MINSIZE,
											ALLOCSET_SMALL_INITSIZE,
											ALLOCSET_SMALL_MAXSIZE);
		}
		else
		{
			/* Clear the existing entry's private context */
			saveCtx = entry->dictCtx;
			MemoryContextResetAndDeleteChildren(saveCtx);
		}

		MemSet(entry, 0, sizeof(TSDictionaryCacheEntry));
		entry->dictId = dictId;
		entry->dictCtx = saveCtx;

		entry->lexizeOid = template->tmpllexize;

		if (OidIsValid(template->tmplinit))
		{
			List	   *dictoptions;