Improve performance of age limit trimming

This does two things: 1. Before this patch, PINCache was naively scheduling a task to trim to age limit *recursively* every time the age limit was set. This makes it so recursive calls are canceled when it detects another recursive call has been kicked off. This is still less than ideal :/ 2. Trimming (mistakenly) used to be a high priority task. Now the age limit itself is set with a high priority, but the trimming is done at a low priority.
pinterest · Jun 7, 2018 · 2c2072c · 2c2072c
1 parent 1f88a1e
commit 2c2072c
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Showing 2 changed files with 27 additions and 5 deletions.
diff --git a/Source/PINDiskCache.m b/Source/PINDiskCache.m
@@ -785,13 +785,24 @@ - (void)trimToAgeLimitRecursively
         return;
 
     NSDate *date = [[NSDate alloc] initWithTimeIntervalSinceNow:-ageLimit];
-    [self trimDiskToDate:date];
+    [self trimToDateAsync:date completion:nil];
 
     dispatch_time_t time = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(ageLimit * NSEC_PER_SEC));
     dispatch_after(time, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void) {
-        [self.operationQueue scheduleOperation:^{
-            [self trimToAgeLimitRecursively];
-        } withPriority:PINOperationQueuePriorityLow];
+        // Ensure that ageLimit is the same as when we were scheduled, otherwise, we've been
+        // rescheduled (another dispatch_after was issued) and should cancel.
+        BOOL shouldReschedule = YES;
+        [self lock];
+            if (ageLimit != _ageLimit) {
+                shouldReschedule = NO;
+            }
+        [self unlock];
+
+        if (shouldReschedule) {
+            [self.operationQueue scheduleOperation:^{
+                [self trimToAgeLimitRecursively];
+            } withPriority:PINOperationQueuePriorityLow];
+        }
     });
 }
 
@@ -1506,7 +1517,9 @@ - (void)setAgeLimit:(NSTimeInterval)ageLimit
             self->_ageLimit = ageLimit;
         [self unlock];
 
-        [self trimToAgeLimitRecursively];
+        [self.operationQueue scheduleOperation:^{
+            [self trimToAgeLimitRecursively];
+        } withPriority:PINOperationQueuePriorityLow];
     } withPriority:PINOperationQueuePriorityHigh];
 }
 

diff --git a/Source/PINMemoryCache.m b/Source/PINMemoryCache.m
@@ -298,6 +298,15 @@ - (void)trimToAgeLimitRecursively
 
     dispatch_time_t time = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(ageLimit * NSEC_PER_SEC));
     dispatch_after(time, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void){
+        // Ensure that ageLimit is the same as when we were scheduled, otherwise, we've been
+        // rescheduled (another dispatch_after was issued) and should cancel.
+        BOOL shouldReschedule = YES;
+        [self lock];
+            if (ageLimit != _ageLimit) {
+                shouldReschedule = NO;
+            }
+        [self unlock];
+
         [self.operationQueue scheduleOperation:^{
             [self trimToAgeLimitRecursively];
         } withPriority:PINOperationQueuePriorityHigh];