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/*
* contrib/pgrowlocks/pgrowlocks.c
*
* Copyright (c) 2005-2006 Tatsuo Ishii
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose, without fee, and without a
* written agreement is hereby granted, provided that the above
* copyright notice and this paragraph and the following two
* paragraphs appear in all copies.
*
* IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
* INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
* DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
* IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
* SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*/
#include "postgres.h"
#include "access/heapam.h"
#include "access/multixact.h"
#include "access/relscan.h"
#include "access/xact.h"
#include "catalog/namespace.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "storage/bufmgr.h"
#include "storage/procarray.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/tqual.h"
PG_MODULE_MAGIC;
PG_FUNCTION_INFO_V1(pgrowlocks);
extern Datum pgrowlocks(PG_FUNCTION_ARGS);
/* ----------
* pgrowlocks:
* returns tids of rows being locked
* ----------
*/
#define NCHARS 32
typedef struct
{
Relation rel;
HeapScanDesc scan;
int ncolumns;
} MyData;
Datum
pgrowlocks(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
HeapScanDesc scan;
HeapTuple tuple;
TupleDesc tupdesc;
AttInMetadata *attinmeta;
Datum result;
MyData *mydata;
Relation rel;
if (SRF_IS_FIRSTCALL())
{
text *relname;
RangeVar *relrv;
MemoryContext oldcontext;
AclResult aclresult;
funcctx = SRF_FIRSTCALL_INIT();
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
attinmeta = TupleDescGetAttInMetadata(tupdesc);
funcctx->attinmeta = attinmeta;
relname = PG_GETARG_TEXT_P(0);
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
rel = heap_openrv(relrv, AccessShareLock);
/* check permissions: must have SELECT on table */
aclresult = pg_class_aclcheck(RelationGetRelid(rel), GetUserId(),
ACL_SELECT);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, ACL_KIND_CLASS,
RelationGetRelationName(rel));
scan = heap_beginscan(rel, SnapshotNow, 0, NULL);
mydata = palloc(sizeof(*mydata));
mydata->rel = rel;
mydata->scan = scan;
mydata->ncolumns = tupdesc->natts;
funcctx->user_fctx = mydata;
MemoryContextSwitchTo(oldcontext);
}
funcctx = SRF_PERCALL_SETUP();
attinmeta = funcctx->attinmeta;
mydata = (MyData *) funcctx->user_fctx;
scan = mydata->scan;
/* scan the relation */
while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
/* must hold a buffer lock to call HeapTupleSatisfiesUpdate */
LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
if (HeapTupleSatisfiesUpdate(tuple->t_data,
GetCurrentCommandId(false),
scan->rs_cbuf) == HeapTupleBeingUpdated)
{
char **values;
int i;
values = (char **) palloc(mydata->ncolumns * sizeof(char *));
i = 0;
values[i++] = (char *) DirectFunctionCall1(tidout, PointerGetDatum(&tuple->t_self));
if (tuple->t_data->t_infomask & HEAP_XMAX_SHARED_LOCK)
values[i++] = pstrdup("Shared");
else
values[i++] = pstrdup("Exclusive");
values[i] = palloc(NCHARS * sizeof(char));
snprintf(values[i++], NCHARS, "%d", HeapTupleHeaderGetXmax(tuple->t_data));
if (tuple->t_data->t_infomask & HEAP_XMAX_IS_MULTI)
{
TransactionId *xids;
int nxids;
int j;
int isValidXid = 0; /* any valid xid ever exists? */
values[i++] = pstrdup("true");
nxids = GetMultiXactIdMembers(HeapTupleHeaderGetXmax(tuple->t_data), &xids);
if (nxids == -1)
{
elog(ERROR, "GetMultiXactIdMembers returns error");
}
values[i] = palloc(NCHARS * nxids);
values[i + 1] = palloc(NCHARS * nxids);
strcpy(values[i], "{");
strcpy(values[i + 1], "{");
for (j = 0; j < nxids; j++)
{
char buf[NCHARS];
if (TransactionIdIsInProgress(xids[j]))
{
if (isValidXid)
{
strcat(values[i], ",");
strcat(values[i + 1], ",");
}
snprintf(buf, NCHARS, "%d", xids[j]);
strcat(values[i], buf);
snprintf(buf, NCHARS, "%d", BackendXidGetPid(xids[j]));
strcat(values[i + 1], buf);
isValidXid = 1;
}
}
strcat(values[i], "}");
strcat(values[i + 1], "}");
i++;
}
else
{
values[i++] = pstrdup("false");
values[i] = palloc(NCHARS * sizeof(char));
snprintf(values[i++], NCHARS, "{%d}", HeapTupleHeaderGetXmax(tuple->t_data));
values[i] = palloc(NCHARS * sizeof(char));
snprintf(values[i++], NCHARS, "{%d}", BackendXidGetPid(HeapTupleHeaderGetXmax(tuple->t_data)));
}
LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
/* build a tuple */
tuple = BuildTupleFromCStrings(attinmeta, values);
/* make the tuple into a datum */
result = HeapTupleGetDatum(tuple);
/* Clean up */
for (i = 0; i < mydata->ncolumns; i++)
pfree(values[i]);
pfree(values);
SRF_RETURN_NEXT(funcctx, result);
}
else
{
LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
}
}
heap_endscan(scan);
heap_close(mydata->rel, AccessShareLock);
SRF_RETURN_DONE(funcctx);
}
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