diff options
Diffstat (limited to 'src/backend/utils/time/snapmgr.c')
| -rw-r--r-- | src/backend/utils/time/snapmgr.c | 33 |
1 files changed, 22 insertions, 11 deletions
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index c2ff5e542b..9100c818f8 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -299,22 +299,33 @@ PushActiveSnapshot(Snapshot snap) } /* - * PushUpdatedSnapshot - * As above, except we set the snapshot's CID to the current CID. + * PushCopiedSnapshot + * As above, except forcibly copy the presented snapshot. + * + * This should be used when the ActiveSnapshot has to be modifiable, for + * example if the caller intends to call UpdateActiveSnapshotCommandId. + * The new snapshot will be released when popped from the stack. */ void -PushUpdatedSnapshot(Snapshot snapshot) +PushCopiedSnapshot(Snapshot snapshot) { - Snapshot newsnap; + PushActiveSnapshot(CopySnapshot(snapshot)); +} - /* - * We cannot risk modifying a snapshot that's possibly already used - * elsewhere, so make a new copy to scribble on. - */ - newsnap = CopySnapshot(snapshot); - newsnap->curcid = GetCurrentCommandId(false); +/* + * UpdateActiveSnapshotCommandId + * + * Update the current CID of the active snapshot. This can only be applied + * to a snapshot that is not referenced elsewhere. + */ +void +UpdateActiveSnapshotCommandId(void) +{ + Assert(ActiveSnapshot != NULL); + Assert(ActiveSnapshot->as_snap->active_count == 1); + Assert(ActiveSnapshot->as_snap->regd_count == 0); - PushActiveSnapshot(newsnap); + ActiveSnapshot->as_snap->curcid = GetCurrentCommandId(false); } /* |