Commit7888b09

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Add BarrierArriveAndDetachExceptLast().

Provide a way for one process to continue the remaining phases of a(previously) parallel computation alone. Later patches will use this toextend Parallel Hash Join.Author: Melanie Plageman <melanieplageman@gmail.com>Reviewed-by: Thomas Munro <thomas.munro@gmail.com>Discussion:https://postgr.es/m/CA%2BhUKG%2BA6ftXPz4oe92%2Bx8Er%2BxpGZqto70-Q_ERwRaSyA%3DafNg%40mail.gmail.com

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Original file line number	Diff line number	Diff line change
`@@ -205,6 +205,28 @@ BarrierArriveAndDetach(Barrier *barrier)`
`205`	`205`	`returnBarrierDetachImpl(barrier, true);`
`206`	`206`	`}`
`207`	`207`
	`208`	`+/*`
	`209`	`+ * Arrive at a barrier, and detach all but the last to arrive. Returns true if`
	`210`	`+ * the caller was the last to arrive, and is therefore still attached.`
	`211`	`+ */`
	`212`	`+bool`
	`213`	`+BarrierArriveAndDetachExceptLast(Barrier*barrier)`
	`214`	`+{`
	`215`	`+SpinLockAcquire(&barrier->mutex);`
	`216`	`+if (barrier->participants>1)`
	`217`	`+{`
	`218`	`+--barrier->participants;`
	`219`	`+SpinLockRelease(&barrier->mutex);`
	`220`	`+`
	`221`	`+return false;`
	`222`	`+}`
	`223`	`+Assert(barrier->participants==1);`
	`224`	`+++barrier->phase;`
	`225`	`+SpinLockRelease(&barrier->mutex);`
	`226`	`+`
	`227`	`+return true;`
	`228`	`+}`
	`229`	`+`
`208`	`230`	`/*`
`209`	`231`	`* Attach to a barrier. All waiting participants will now wait for this`
`210`	`232`	`* participant to call BarrierArriveAndWait(), BarrierDetach() or`

Lines changed: 1 addition & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -37,6 +37,7 @@ typedef struct Barrier`
`37`	`37`	`externvoidBarrierInit(Barrier*barrier,intnum_workers);`
`38`	`38`	`externboolBarrierArriveAndWait(Barrier*barrier,uint32wait_event_info);`
`39`	`39`	`externboolBarrierArriveAndDetach(Barrier*barrier);`
	`40`	`+externboolBarrierArriveAndDetachExceptLast(Barrier*barrier);`
`40`	`41`	`externintBarrierAttach(Barrier*barrier);`
`41`	`42`	`externboolBarrierDetach(Barrier*barrier);`
`42`	`43`	`externintBarrierPhase(Barrier*barrier);`

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