C++ PointerIsValid函数代码示例

/*
 * Print the value of a Datum given its type.
 */
static void
_outDatum(StringInfo str, Datum value, int typlen, bool typbyval)
{
	Size		length;
	char	   *s;

	if (typbyval)
	{
		s = (char *) (&value);
		appendBinaryStringInfo(str, s, sizeof(Datum));
	}
	else
	{
		s = (char *) DatumGetPointer(value);
		if (!PointerIsValid(s))
		{
			length = 0;
			appendBinaryStringInfo(str, (char *)&length, sizeof(Size));
		}
		else
		{
			length = datumGetSize(value, typbyval, typlen);
			appendBinaryStringInfo(str, (char *)&length, sizeof(Size));
			appendBinaryStringInfo(str, s, length);
		}
	}
}

/*
 * CleanupInvalidationState
 *		Mark the current backend as no longer active.
 *
 * This function is called via on_shmem_exit() during backend shutdown.
 *
 * arg is really of type "SISeg*".
 */
static void
CleanupInvalidationState(int status, Datum arg)
{
	SISeg	   *segP = (SISeg *) DatumGetPointer(arg);
	ProcState  *stateP;
	int			i;

	Assert(PointerIsValid(segP));

	LWLockAcquire(SInvalWriteLock, LW_EXCLUSIVE);

	stateP = &segP->procState[MyBackendId - 1];

	/* Update next local transaction ID for next holder of this backendID */
	stateP->nextLXID = nextLocalTransactionId;

	/* Mark myself inactive */
	stateP->procPid = 0;
	stateP->proc = NULL;
	stateP->nextMsgNum = 0;
	stateP->resetState = false;
	stateP->signaled = false;

	/* Recompute index of last active backend */
	for (i = segP->lastBackend; i > 0; i--)
	{
		if (segP->procState[i - 1].procPid != 0)
			break;
	}
	segP->lastBackend = i;

	LWLockRelease(SInvalWriteLock);
}

int
inv_seek(LargeObjectDesc *obj_desc, int offset, int whence)
{
	Assert(PointerIsValid(obj_desc));

	switch (whence)
	{
		case SEEK_SET:
			if (offset < 0)
				elog(ERROR, "invalid seek offset: %d", offset);
			obj_desc->offset = offset;
			break;
		case SEEK_CUR:
			if (offset < 0 && obj_desc->offset < ((uint32) (-offset)))
				elog(ERROR, "invalid seek offset: %d", offset);
			obj_desc->offset += offset;
			break;
		case SEEK_END:
			{
				uint32		size = inv_getsize(obj_desc);

				if (offset < 0 && size < ((uint32) (-offset)))
					elog(ERROR, "invalid seek offset: %d", offset);
				obj_desc->offset = size + offset;
			}
			break;
		default:
			elog(ERROR, "invalid whence: %d", whence);
	}
	return obj_desc->offset;
}

/*
 * InitCatalogCache - initialize the caches
 *
 * Note that no database access is done here; we only allocate memory
 * and initialize the cache structure.  Interrogation of the database
 * to complete initialization of a cache happens upon first use
 * of that cache.
 */
void
InitCatalogCache(void)
{
	int			cacheId;
	int			i,
				j;

	StaticAssertStmt(SysCacheSize == (int) lengthof(cacheinfo),
					 "SysCacheSize does not match syscache.c's array");

	Assert(!CacheInitialized);

	SysCacheRelationOidSize = SysCacheSupportingRelOidSize = 0;

	for (cacheId = 0; cacheId < SysCacheSize; cacheId++)
	{
		SysCache[cacheId] = InitCatCache(cacheId,
										 cacheinfo[cacheId].reloid,
										 cacheinfo[cacheId].indoid,
										 cacheinfo[cacheId].nkeys,
										 cacheinfo[cacheId].key,
										 cacheinfo[cacheId].nbuckets);
		if (!PointerIsValid(SysCache[cacheId]))
			elog(ERROR, "could not initialize cache %u (%d)",
				 cacheinfo[cacheId].reloid, cacheId);
		/* Accumulate data for OID lists, too */
		SysCacheRelationOid[SysCacheRelationOidSize++] =
			cacheinfo[cacheId].reloid;
		SysCacheSupportingRelOid[SysCacheSupportingRelOidSize++] =
			cacheinfo[cacheId].reloid;
		SysCacheSupportingRelOid[SysCacheSupportingRelOidSize++] =
			cacheinfo[cacheId].indoid;
		/* see comments for RelationInvalidatesSnapshotsOnly */
		Assert(!RelationInvalidatesSnapshotsOnly(cacheinfo[cacheId].reloid));
	}

	Assert(SysCacheRelationOidSize <= lengthof(SysCacheRelationOid));
	Assert(SysCacheSupportingRelOidSize <= lengthof(SysCacheSupportingRelOid));

	/* Sort and de-dup OID arrays, so we can use binary search. */
	pg_qsort(SysCacheRelationOid, SysCacheRelationOidSize,
			 sizeof(Oid), oid_compare);
	for (i = 1, j = 0; i < SysCacheRelationOidSize; i++)
	{
		if (SysCacheRelationOid[i] != SysCacheRelationOid[j])
			SysCacheRelationOid[++j] = SysCacheRelationOid[i];
	}
	SysCacheRelationOidSize = j + 1;

	pg_qsort(SysCacheSupportingRelOid, SysCacheSupportingRelOidSize,
			 sizeof(Oid), oid_compare);
	for (i = 1, j = 0; i < SysCacheSupportingRelOidSize; i++)
	{
		if (SysCacheSupportingRelOid[i] != SysCacheSupportingRelOid[j])
			SysCacheSupportingRelOid[++j] = SysCacheSupportingRelOid[i];
	}
	SysCacheSupportingRelOidSize = j + 1;

	CacheInitialized = true;
}

Datum
zlib_constructor(PG_FUNCTION_ARGS)
{

	/* PG_GETARG_POINTER(0) is TupleDesc that is currently unused.
	 * It is passed as NULL */

	StorageAttributes *sa = PG_GETARG_POINTER(1);
	CompressionState *cs	   = palloc0(sizeof(CompressionState));
	zlib_state	   *state	= palloc0(sizeof(zlib_state));
	bool			  compress = PG_GETARG_BOOL(2);

	cs->opaque = (void *) state;
	cs->desired_sz = NULL;

	Insist(PointerIsValid(sa->comptype));

	if (sa->complevel == 0)
		sa->complevel = 1;

	state->level = sa->complevel;
	state->compress = compress;
	state->compress_fn = compress2;
	state->decompress_fn = uncompress;

	PG_RETURN_POINTER(cs);

}

/*
 * CleanupInvalidationState
 *		Mark the current backend as no longer active.
 *
 * This function is called via on_shmem_exit() during backend shutdown,
 * so the caller has NOT acquired the lock for us.
 *
 * arg is really of type "SISeg*".
 */
static void
CleanupInvalidationState(int status, Datum arg)
{
	SISeg	   *segP = (SISeg *) DatumGetPointer(arg);
	int			i;

	Assert(PointerIsValid(segP));

	LWLockAcquire(SInvalLock, LW_EXCLUSIVE);

	/* Update next local transaction ID for next holder of this backendID */
	segP->nextLXID[MyBackendId - 1] = nextLocalTransactionId;

	/* Mark myself inactive */
	segP->procState[MyBackendId - 1].nextMsgNum = -1;
	segP->procState[MyBackendId - 1].resetState = false;

	/* Recompute index of last active backend */
	for (i = segP->lastBackend; i > 0; i--)
	{
		if (segP->procState[i - 1].nextMsgNum >= 0)
			break;
	}
	segP->lastBackend = i;

	/* Adjust free slot count */
	segP->freeBackends++;

	LWLockRelease(SInvalLock);
}

int64
inv_tell(LargeObjectDesc *obj_desc)
{
	Assert(PointerIsValid(obj_desc));

	return obj_desc->offset;
}

/*
 * Determine size of a large object
 *
 * NOTE: LOs can contain gaps, just like Unix files.  We actually return
 * the offset of the last byte + 1.
 */
static uint32
inv_getsize(LargeObjectDesc *obj_desc)
{
	bool		found = false;
	uint32		lastbyte = 0;
	ScanKeyData skey[1];
	IndexScanDesc sd;
	HeapTuple	tuple;

	Assert(PointerIsValid(obj_desc));

	open_lo_relation();

	ScanKeyInit(&skey[0],
				Anum_pg_largeobject_loid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(obj_desc->id));

	sd = index_beginscan(lo_heap_r, lo_index_r,
						 obj_desc->snapshot, 1, skey);

	/*
	 * Because the pg_largeobject index is on both loid and pageno, but we
	 * constrain only loid, a backwards scan should visit all pages of the
	 * large object in reverse pageno order.  So, it's sufficient to examine
	 * the first valid tuple (== last valid page).
	 */
	while ((tuple = index_getnext(sd, BackwardScanDirection)) != NULL)
	{
		Form_pg_largeobject data;
		bytea	   *datafield;
		bool		pfreeit;

		found = true;
		if (HeapTupleHasNulls(tuple))	/* paranoia */
			elog(ERROR, "null field found in pg_largeobject");
		data = (Form_pg_largeobject) GETSTRUCT(tuple);
		datafield = &(data->data);		/* see note at top of file */
		pfreeit = false;
		if (VARATT_IS_EXTENDED(datafield))
		{
			datafield = (bytea *)
				heap_tuple_untoast_attr((struct varlena *) datafield);
			pfreeit = true;
		}
		lastbyte = data->pageno * LOBLKSIZE + getbytealen(datafield);
		if (pfreeit)
			pfree(datafield);
		break;
	}

	index_endscan(sd);

	if (!found)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("large object %u does not exist", obj_desc->id)));
	return lastbyte;
}

/*
 * Closes a large object descriptor previously made by inv_open(), and
 * releases the long-term memory used by it.
 */
void
inv_close(LargeObjectDesc *obj_desc)
{
	Assert(PointerIsValid(obj_desc));
	if (obj_desc->snapshot != SnapshotNow)
		FreeSnapshot(obj_desc->snapshot);
	pfree(obj_desc);
}

/*
 * Closes a large object descriptor previously made by inv_open(), and
 * releases the long-term memory used by it.
 */
void
inv_close(LargeObjectDesc *obj_desc)
{
	Assert(PointerIsValid(obj_desc));

	UnregisterSnapshotFromOwner(obj_desc->snapshot,
								TopTransactionResourceOwner);

	pfree(obj_desc);
}

HeapTuple
SearchSysCache4(int cacheId,
				Datum key1, Datum key2, Datum key3, Datum key4)
{
	Assert(cacheId >= 0 && cacheId < SysCacheSize &&
		   PointerIsValid(SysCache[cacheId]));
	Assert(SysCache[cacheId]->cc_nkeys == 4);

	return SearchCatCache4(SysCache[cacheId], key1, key2, key3, key4);
}

HeapTuple
SearchSysCache1(int cacheId,
				Datum key1)
{
	Assert(cacheId >= 0 && cacheId < SysCacheSize &&
		   PointerIsValid(SysCache[cacheId]));
	Assert(SysCache[cacheId]->cc_nkeys == 1);

	return SearchCatCache1(SysCache[cacheId], key1);
}

struct catclist *
SearchSysCacheList(int cacheId, int nkeys,
				   Datum key1, Datum key2, Datum key3, Datum key4)
{
	if (cacheId < 0 || cacheId >= SysCacheSize ||
		!PointerIsValid(SysCache[cacheId]))
		elog(ERROR, "invalid cache id: %d", cacheId);

	return SearchCatCacheList(SysCache[cacheId], nkeys,
							  key1, key2, key3, key4);
}

Datum
zlib_destructor(PG_FUNCTION_ARGS)
{
	CompressionState *cs = PG_GETARG_POINTER(0);

	Insist(PointerIsValid(cs->opaque));
	pfree(cs->opaque);

	PG_RETURN_VOID();

}

/*
 * ExceptionalCondition - Handles the failure of an Assert()
 */
void
ExceptionalCondition(const char *conditionName,
					 const char *errorType,
					 const char *fileName,
					 int lineNumber)
{
	void *array[32];
	size_t size;

	if (!PointerIsValid(conditionName)
		|| !PointerIsValid(fileName)
		|| !PointerIsValid(errorType))
		write_stderr("TRAP: ExceptionalCondition: bad arguments\n");
	else
	{
		write_stderr("TRAP: %s(\"%s\", File: \"%s\", Line: %d, PID: %d, Query: %s)\n",
					 errorType, conditionName,
					 fileName, lineNumber, getpid(), debug_query_string);
	}

	/* dump stack trace */
	size = backtrace(array, 32);
	fprintf(stderr, "Assertion failure (PID %d)\n", MyProcPid);
	fprintf(stderr, "version: %s\n", PIPELINE_VERSION_STR);
	fprintf(stderr, "backtrace:\n");
	backtrace_symbols_fd(array, size, STDERR_FILENO);

	/* Usually this shouldn't be needed, but make sure the msg went out */
	fflush(stderr);

#ifdef SLEEP_ON_ASSERT

	/*
	 * It would be nice to use pg_usleep() here, but only does 2000 sec or 33
	 * minutes, which seems too short.
	 */
	sleep(1000000);
#endif

	abort();
}