Merge pull request #4 from creativecreature/refresh-deletions

fix: Improve the refresh deletions

cache.go

@@ -166,3 +166,10 @@ func (c *Client) set(key string, value any, isMissingRecord bool) bool {
 	shard := c.getShard(key)
 	return shard.set(key, value, isMissingRecord)
 }
+
+// get retrieves a single value from the cache.
+func (c *Client) get(key string) (any, bool) {
+	shard := c.getShard(key)
+	value, ok, _, _ := shard.get(key)
+	return value, ok
+}

get_test.go

@@ -429,7 +429,6 @@ func TestGetFetchBatchStampedeProtection(t *testing.T) {
 	<-fetchObserver.FetchCompleted
 	fetchObserver.AssertRequestedRecords(t, ids)
 	fetchObserver.AssertFetchCount(t, 1)
-	fetchObserver.Clear()
 
 	// Set the clock to be just before the min cache refresh threshold.
 	// This should not be enough to make the cache call our fetchFn.

passthrough_test.go

@@ -177,8 +177,8 @@ func TestHalfPassthroughBatch(t *testing.T) {
 	}
 
 	// It's not possible to know how many requests we'll let through. We expect
-	// half, which would be 50, but let's use 10 as a margin of safety.
-	safetyMargin := 10
+	// half, which would be 50, but let's use 15 as a margin of safety.
+	safetyMargin := 15
 	for i := 0; i < (numPassthroughs/2)-safetyMargin; i++ {
 		<-fetchObserver.FetchCompleted
 	}

refresh.go

@@ -26,11 +26,21 @@ func refreshBatch[T any](c *Client, ids []string, keyFn KeyFn, fetchFn BatchFetc
 		return
 	}
 
-	if c.storeMisses && len(response) < len(ids) {
-		for _, id := range ids {
-			if v, ok := response[id]; !ok {
-				c.set(keyFn(id), v, true)
-			}
+	// Check if any of the records have been deleted at the data source.
+	for _, id := range ids {
+		_, okCache := c.get(keyFn(id))
+		v, okResponse := response[id]
+
+		if okResponse {
+			continue
+		}
+
+		if !c.storeMisses && !okResponse && okCache {
+			c.Delete(keyFn(id))
+		}
+
+		if c.storeMisses && !okResponse {
+			c.set(keyFn(id), v, true)
 		}
 	}