greenplumn cdbdistributedxacts 源码
greenplumn cdbdistributedxacts 代码
文件路径：/src/backend/cdb/cdbdistributedxacts.c
/*-------------------------------------------------------------------------
*
* cdbdistributedxacts.c
* Set-returning function to view gp_distributed_xacts table.
*
* IDENTIFICATION
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "funcapi.h"
#include "access/heapam.h"
#include "catalog/pg_type.h"
#include "utils/builtins.h"
#include "cdb/cdbutil.h"
#include "cdb/cdbtm.h"
Datum gp_distributed_xacts__(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(gp_distributed_xacts__);
/*
* pgdatabasev - produce a view of gp_distributed_xacts to include transient state
*/
Datum
gp_distributed_xacts__(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
TMGALLXACTSTATUS *allDistributedXactStatus;
if (SRF_IS_FIRSTCALL())
{
TupleDesc tupdesc;
MemoryContext oldcontext;
/* create a function context for cross-call persistence */
funcctx = SRF_FIRSTCALL_INIT();
/*
* switch to memory context appropriate for multiple function calls
*/
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
/* build tupdesc for result tuples */
/* this had better match gp_distributed_xacts view in system_views.sql */
tupdesc = CreateTemplateTupleDesc(4);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "distributed_xid",
XIDOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "state",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "gp_session_id",
INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 4, "xmin_distributed_snapshot",
XIDOID, -1, 0);
funcctx->tuple_desc = BlessTupleDesc(tupdesc);
/*
* Collect all the locking information that we will format and send
* out as a result set.
*/
getAllDistributedXactStatus(&allDistributedXactStatus);
funcctx->user_fctx = (void *) allDistributedXactStatus;
MemoryContextSwitchTo(oldcontext);
}
funcctx = SRF_PERCALL_SETUP();
allDistributedXactStatus = (TMGALLXACTSTATUS *) funcctx->user_fctx;
while (true)
{
TMGXACTSTATUS *distributedXactStatus;
Datum values[6];
bool nulls[6];
HeapTuple tuple;
Datum result;
if (!getNextDistributedXactStatus(allDistributedXactStatus,
&distributedXactStatus))
break;
/*
* Form tuple with appropriate data.
*/
MemSet(values, 0, sizeof(values));
MemSet(nulls, false, sizeof(nulls));
values[0] = TransactionIdGetDatum(distributedXactStatus->gxid);
values[1] = CStringGetTextDatum(DtxStateToString(distributedXactStatus->state));
values[2] = UInt32GetDatum(distributedXactStatus->sessionId);
values[3] = TransactionIdGetDatum(distributedXactStatus->xminDistributedSnapshot);
tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
result = HeapTupleGetDatum(tuple);
SRF_RETURN_NEXT(funcctx, result);
}
SRF_RETURN_DONE(funcctx);
}
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