Github user ben-manes commented on a diff in the pull request:
https://github.com/apache/storm/pull/2218#discussion_r129211231
--- Diff:
storm-client/src/jvm/org/apache/storm/topology/SimpleWindowPartitionCache.java
---
@@ -0,0 +1,182 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.storm.topology;
+
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.locks.ReentrantLock;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A simple implementation that evicts the largest un-pinned entry from
the cache. This works well
+ * for caching window partitions since the access pattern is mostly
sequential scans.
+ */
+public class SimpleWindowPartitionCache<K, V> implements
WindowPartitionCache<K, V> {
+ private static final Logger LOG =
LoggerFactory.getLogger(SimpleWindowPartitionCache.class);
+
+ private final ConcurrentSkipListMap<K, V> map = new
ConcurrentSkipListMap<>();
+ private final Map<K, Long> pinned = new HashMap<>();
+ private final long maximumSize;
+ private final RemovalListener<K, V> removalListener;
+ private final CacheLoader<K, V> cacheLoader;
+ private final ReentrantLock lock = new ReentrantLock(true);
+ private int size;
+
+ @Override
+ public V get(K key) {
+ return getOrLoad(key, false);
+ }
+
+ @Override
+ public V getPinned(K key) {
+ return getOrLoad(key, true);
+ }
+
+ @Override
+ public boolean unpin(K key) {
+ LOG.debug("unpin '{}'", key);
+ boolean res = false;
+ try {
+ lock.lock();
+ if (pinned.compute(key, (k, v) -> v == null ? 0 : v - 1) <= 0)
{
+ pinned.remove(key);
+ res = true;
+ }
+ } finally {
+ lock.unlock();
+ }
+ LOG.debug("pinned '{}'", pinned);
+ return res;
+ }
+
+ @Override
+ public ConcurrentMap<K, V> asMap() {
+ return map;
+ }
+
+ @Override
+ public void invalidate(K key) {
+ if (isPinned(key)) {
+ LOG.debug("Entry '{}' is pinned, skipping invalidation", key);
+ } else {
+ LOG.debug("Invalidating entry '{}'", key);
+ V val = map.remove(key);
+ try {
+ lock.lock();
+ --size;
--- End diff --
if the key isn't in the cache (e.g. concurrent invalidations) then this
will decrease incorrectly. I think you need to check `val` and skip the locking
code if not present.
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