scwhittle commented on code in PR #33566:
URL: https://github.com/apache/beam/pull/33566#discussion_r1912906834
##########
sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/spanner/changestreams/dofn/DetectNewPartitionsDoFn.java:
##########
@@ -60,6 +62,7 @@ public class DetectNewPartitionsDoFn extends
DoFn<PartitionMetadata, PartitionMe
private final MapperFactory mapperFactory;
private final ActionFactory actionFactory;
private final ChangeStreamMetrics metrics;
+ private final CacheFactory cacheFactory;
Review Comment:
I'm not sure that this will result in multiple DoFn instances sharing the
same cache.
Each DoFn is deserialized separately, so I think that they would each have
their own CacheFactory instance, and then each one would get a separate cache.
You could make it static but then the cache woudl be shared against possibly
different instances of DetectNewPartitionsDoFn in the graph (which maybe could
have different configuration).
For Kafak reads, Stephen was using this approach:
```
private static final Map<Long, StaticState> StaticStateCache = new
ConcurrentHashMap<>();
private static final AtomicLong FN_ID = new AtomicLong();
// A unique identifier for the instance. Generally unique unless the ID
generator overflows.
private final long fnId = FN_ID.getAndIncrement();
```
Then within a graph you might have mulitple of the DoFn with unique fnId
variables. When deserialized, each of the deserialized instances will have the
fnId set to the same value. Then the static state cache can be used to have the
same state for a given node in the graph across all of the deserialized
instances.
Since this is tricky to get right, it seems like perhaps we could come up
with some annotation or other helper class to do this.
##########
sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/spanner/changestreams/cache/LoadingWatermarkCache.java:
##########
@@ -0,0 +1,56 @@
+/*
+ * 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.beam.sdk.io.gcp.spanner.changestreams.cache;
+
+import com.google.cloud.Timestamp;
+import java.time.Duration;
+import java.util.Optional;
+import java.util.concurrent.ExecutionException;
+import javax.annotation.Nullable;
+import
org.apache.beam.sdk.io.gcp.spanner.changestreams.dao.PartitionMetadataDao;
+import
org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.CacheBuilder;
+import
org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.CacheLoader;
+import
org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.LoadingCache;
+
+public class LoadingWatermarkCache implements WatermarkCache {
+ private static final Object MIN_WATERMARK_KEY = new Object();
+
+ private final LoadingCache<Object, Optional<Timestamp>> cache;
+
+ public LoadingWatermarkCache(PartitionMetadataDao dao,
org.joda.time.Duration refreshRate) {
+ this.cache =
+ CacheBuilder.newBuilder()
+ .refreshAfterWrite(Duration.ofMillis(refreshRate.getMillis()))
Review Comment:
think you need to make the loading async
I think you can use this method:
https://guava.dev/releases/22.0/api/docs/com/google/common/cache/CacheLoader.html#asyncReloading-com.google.common.cache.CacheLoader-java.util.concurrent.Executor-
##########
sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/spanner/changestreams/cache/CacheFactory.java:
##########
@@ -0,0 +1,49 @@
+/*
+ * 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.beam.sdk.io.gcp.spanner.changestreams.cache;
+
+import java.io.Serializable;
+import javax.annotation.Nullable;
+import org.apache.beam.sdk.io.gcp.spanner.changestreams.dao.DaoFactory;
+import org.joda.time.Duration;
+
+@SuppressWarnings({"initialization.fields.uninitialized", "nullness"})
+public class CacheFactory implements Serializable {
+
+ private static final long serialVersionUID = -8722905670370252723L;
+ private final DaoFactory daoFactory;
+ private final @Nullable Duration refreshRate;
+ private transient WatermarkCache watermarkCacheInstance;
+
+ public CacheFactory(DaoFactory daoFactory, @Nullable Duration
watermarkRefreshRate) {
+ this.daoFactory = daoFactory;
+ this.refreshRate = watermarkRefreshRate;
+ }
+
+ public synchronized WatermarkCache getWatermarkCache() {
+ if (watermarkCacheInstance == null) {
+ if (refreshRate == null) {
+ watermarkCacheInstance = new
NoOpWatermarkCache(daoFactory.getPartitionMetadataDao());
Review Comment:
alternatively you could set this in the constructor and in readObject
https://stackoverflow.com/questions/4119181/java-object-serialization-readobject-defaultreadobject
##########
sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/spanner/changestreams/cache/CacheFactory.java:
##########
@@ -0,0 +1,49 @@
+/*
+ * 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.beam.sdk.io.gcp.spanner.changestreams.cache;
+
+import java.io.Serializable;
+import javax.annotation.Nullable;
+import org.apache.beam.sdk.io.gcp.spanner.changestreams.dao.DaoFactory;
+import org.joda.time.Duration;
+
+@SuppressWarnings({"initialization.fields.uninitialized", "nullness"})
Review Comment:
can you fix these instead of suppressing? Can watermarkCacheInstance just be
marked nullable, I think it might fix both
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