diff options
Diffstat (limited to 'src/backend/commands/async.c')
| -rw-r--r-- | src/backend/commands/async.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/src/backend/commands/async.c b/src/backend/commands/async.c index 7c133ec8d33..42b232d98b1 100644 --- a/src/backend/commands/async.c +++ b/src/backend/commands/async.c @@ -490,7 +490,12 @@ asyncQueuePageDiff(int p, int q) return diff; } -/* Is p < q, accounting for wraparound? */ +/* + * Is p < q, accounting for wraparound? + * + * Since asyncQueueIsFull() blocks creation of a page that could precede any + * extant page, we need not assess entries within a page. + */ static bool asyncQueuePagePrecedes(int p, int q) { @@ -1352,8 +1357,8 @@ asyncQueueIsFull(void) * logically precedes the current global tail pointer, ie, the head * pointer would wrap around compared to the tail. We cannot create such * a head page for fear of confusing slru.c. For safety we round the tail - * pointer back to a segment boundary (compare the truncation logic in - * asyncQueueAdvanceTail). + * pointer back to a segment boundary (truncation logic in + * asyncQueueAdvanceTail does not do this, so doing it here is optional). * * Note that this test is *not* dependent on how much space there is on * the current head page. This is necessary because asyncQueueAddEntries |