/*
* index_parallelscan_initialize - initialize parallel scan
*
* We initialize both the ParallelIndexScanDesc proper and the AM-specific
* information which follows it.
*
* This function calls access method specific initialization routine to
* initialize am specific information. Call this just once in the leader
* process; then, individual workers attach via index_beginscan_parallel.
*/
void
index_parallelscan_initialize(Relation heapRelation, Relation indexRelation,
Snapshot snapshot, ParallelIndexScanDesc target)
{
Size offset;
RELATION_CHECKS;
offset = add_size(offsetof(ParallelIndexScanDescData, ps_snapshot_data),
EstimateSnapshotSpace(snapshot));
offset = MAXALIGN(offset);
target->ps_relid = RelationGetRelid(heapRelation);
target->ps_indexid = RelationGetRelid(indexRelation);
target->ps_offset = offset;
SerializeSnapshot(snapshot, target->ps_snapshot_data);
/* aminitparallelscan is optional; assume no-op if not provided by AM */
if (indexRelation->rd_amroutine->aminitparallelscan != NULL)
{
void *amtarget;
amtarget = OffsetToPointer(target, offset);
indexRelation->rd_amroutine->aminitparallelscan(amtarget);
}
}
/* ----------------------------------------------------------------
* ExecBitmapHeapEstimate
*
* estimates the space required to serialize bitmap scan node.
* ----------------------------------------------------------------
*/
void
ExecBitmapHeapEstimate(BitmapHeapScanState *node,
ParallelContext *pcxt)
{
EState *estate = node->ss.ps.state;
node->pscan_len = add_size(offsetof(ParallelBitmapHeapState,
phs_snapshot_data),
EstimateSnapshotSpace(estate->es_snapshot));
shm_toc_estimate_chunk(&pcxt->estimator, node->pscan_len);
shm_toc_estimate_keys(&pcxt->estimator, 1);
}
Size
table_parallelscan_estimate(Relation rel, Snapshot snapshot)
{
Size sz = 0;
if (IsMVCCSnapshot(snapshot))
sz = add_size(sz, EstimateSnapshotSpace(snapshot));
else
Assert(snapshot == SnapshotAny);
sz = add_size(sz, rel->rd_tableam->parallelscan_estimate(rel));
return sz;
}
/*
* index_parallelscan_estimate - estimate shared memory for parallel scan
*
* Currently, we don't pass any information to the AM-specific estimator,
* so it can probably only return a constant. In the future, we might need
* to pass more information.
*/
Size
index_parallelscan_estimate(Relation indexRelation, Snapshot snapshot)
{
Size nbytes;
RELATION_CHECKS;
nbytes = offsetof(ParallelIndexScanDescData, ps_snapshot_data);
nbytes = add_size(nbytes, EstimateSnapshotSpace(snapshot));
nbytes = MAXALIGN(nbytes);
/*
* If amestimateparallelscan is not provided, assume there is no
* AM-specific data needed. (It's hard to believe that could work, but
* it's easy enough to cater to it here.)
*/
if (indexRelation->rd_amroutine->amestimateparallelscan != NULL)
nbytes = add_size(nbytes,
indexRelation->rd_amroutine->amestimateparallelscan());
return nbytes;
}