Use CloseableRetryableRefreshListener to drain ongoing after refresh …

…tasks on relocation (opensearch-project#8683)

* Use CloesableRetryableRefreshListener to drain ongoing after refresh tasks on relocation
---------
Signed-off-by: Ashish Singh <[email protected]>

server/src/main/java/org/opensearch/index/shard/CheckpointRefreshListener.java

@@ -21,7 +21,7 @@
  *
  * @opensearch.internal
  */
-public class CheckpointRefreshListener implements ReferenceManager.RefreshListener {
+public class CheckpointRefreshListener extends CloseableRetryableRefreshListener {
 
     protected static Logger logger = LogManager.getLogger(CheckpointRefreshListener.class);
 
@@ -39,12 +39,18 @@ public void beforeRefresh() throws IOException {
     }
 
     @Override
-    public void afterRefresh(boolean didRefresh) throws IOException {
+    protected boolean performAfterRefresh(boolean didRefresh, boolean isRetry) {
         if (didRefresh
             && shard.state() == IndexShardState.STARTED
             && shard.getReplicationTracker().isPrimaryMode()
             && !shard.indexSettings.isSegRepWithRemoteEnabled()) {
             publisher.publish(shard, shard.getLatestReplicationCheckpoint());
         }
+        return true;
+    }
+
+    @Override
+    protected Logger getLogger() {
+        return logger;
     }
 }

server/src/main/java/org/opensearch/index/shard/CloseableRetryableRefreshListener.java

@@ -0,0 +1,143 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.index.shard;
+
+import org.apache.logging.log4j.Logger;
+import org.apache.lucene.search.ReferenceManager;
+import org.opensearch.common.unit.TimeValue;
+import org.opensearch.threadpool.ThreadPool;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * RefreshListener that runs afterRefresh method if and only if there is a permit available. Once the listener
+ * is closed, all the permits are acquired and there are no available permits to afterRefresh. This abstract class provides
+ * necessary abstract methods to schedule retry.
+ */
+public abstract class CloseableRetryableRefreshListener implements ReferenceManager.RefreshListener, Closeable {
+
+    /**
+     * Total permits = 1 ensures that there is only single instance of performAfterRefresh that is running at a time.
+     * In case there are use cases where concurrency is required, the total permit variable can be put inside the ctor.
+     */
+    private static final int TOTAL_PERMITS = 1;
+
+    private final Semaphore semaphore = new Semaphore(TOTAL_PERMITS);
+
+    private final ThreadPool threadPool;
+
+    /**
+     * This boolean is used to ensure that there is only 1 retry scheduled/running at any time.
+     */
+    private final AtomicBoolean retryScheduled = new AtomicBoolean(false);
+
+    public CloseableRetryableRefreshListener() {
+        this.threadPool = null;
+    }
+
+    public CloseableRetryableRefreshListener(ThreadPool threadPool) {
+        this.threadPool = threadPool;
+    }
+
+    @Override
+    public final void afterRefresh(boolean didRefresh) throws IOException {
+        boolean successful;
+        boolean permitAcquired = semaphore.tryAcquire();
+        try {
+            successful = permitAcquired && performAfterRefresh(didRefresh, false);
+        } finally {
+            if (permitAcquired) {
+                semaphore.release();
+            }
+        }
+        scheduleRetry(successful, didRefresh, permitAcquired);
+    }
+
+    protected String getRetryThreadPoolName() {
+        return null;
+    }
+
+    protected TimeValue getNextRetryInterval() {
+        return null;
+    }
+
+    private void scheduleRetry(TimeValue interval, String retryThreadPoolName, boolean didRefresh, boolean isRetry) {
+        if (this.threadPool == null
+            || interval == null
+            || retryThreadPoolName == null
+            || ThreadPool.THREAD_POOL_TYPES.containsKey(retryThreadPoolName) == false
+            || interval == TimeValue.MINUS_ONE
+            || retryScheduled.compareAndSet(false, true) == false) {
+            return;
+        }
+        boolean scheduled = false;
+        try {
+            this.threadPool.schedule(() -> {
+                boolean successful;
+                boolean permitAcquired = semaphore.tryAcquire();
+                try {
+                    successful = permitAcquired && performAfterRefresh(didRefresh, isRetry);
+                } finally {
+                    if (permitAcquired) {
+                        semaphore.release();
+                    }
+                    retryScheduled.set(false);
+                }
+                scheduleRetry(successful, didRefresh, isRetry || permitAcquired);
+            }, interval, retryThreadPoolName);
+            scheduled = true;
+            getLogger().info("Scheduled retry with didRefresh={} isRetry={}", didRefresh, isRetry);
+        } finally {
+            if (scheduled == false) {
+                retryScheduled.set(false);
+            }
+        }
+    }
+
+    /**
+     * Schedules the retry based on the {@code afterRefreshSuccessful} value.
+     *
+     * @param afterRefreshSuccessful is sent true if the performAfterRefresh(..) is successful.
+     * @param didRefresh             if the refresh did open a new reference then didRefresh will be true
+     * @param isRetry                if this is a failure or permit was not acquired.
+     */
+    private void scheduleRetry(boolean afterRefreshSuccessful, boolean didRefresh, boolean isRetry) {
+        if (afterRefreshSuccessful == false) {
+            scheduleRetry(getNextRetryInterval(), getRetryThreadPoolName(), didRefresh, isRetry);
+        }
+    }
+
+    /**
+     * This method needs to be overridden and be provided with what needs to be run on after refresh.
+     *
+     * @param didRefresh true if the refresh opened a new reference
+     * @param isRetry    true if this is a retry attempt
+     * @return true if a retry is needed else false.
+     */
+    protected abstract boolean performAfterRefresh(boolean didRefresh, boolean isRetry);
+
+    @Override
+    public final void close() throws IOException {
+        try {
+            if (semaphore.tryAcquire(TOTAL_PERMITS, 10, TimeUnit.MINUTES)) {
+                assert semaphore.availablePermits() == 0;
+            } else {
+                throw new RuntimeException("timeout while closing gated refresh listener");
+            }
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    protected abstract Logger getLogger();
+}

server/src/main/java/org/opensearch/index/shard/IndexShard.java

@@ -338,6 +338,8 @@ Runnable getGlobalCheckpointSyncer() {
     private final boolean isTimeSeriesIndex;
     private final RemoteRefreshSegmentPressureService remoteRefreshSegmentPressureService;
 
+    private final List<ReferenceManager.RefreshListener> internalRefreshListener = new ArrayList<>();
+
     public IndexShard(
         final ShardRouting shardRouting,
         final IndexSettings indexSettings,
@@ -812,6 +814,13 @@ public void relocated(
                 if (syncTranslog) {
                     maybeSync();
                 }
+
+                // Ensures all in-flight remote store operations drain, before we perform the handoff.
+                internalRefreshListener.stream()
+                    .filter(refreshListener -> refreshListener instanceof Closeable)
+                    .map(refreshListener -> (Closeable) refreshListener)
+                    .close();
+
                 // no shard operation permits are being held here, move state from started to relocated
                 assert indexShardOperationPermits.getActiveOperationsCount() == OPERATIONS_BLOCKED
                     : "in-flight operations in progress while moving shard state to relocated";
@@ -3659,7 +3668,7 @@ private EngineConfig newEngineConfig(LongSupplier globalCheckpointSupplier) thro
             }
         };
 
-        final List<ReferenceManager.RefreshListener> internalRefreshListener = new ArrayList<>();
+        internalRefreshListener.clear();
         internalRefreshListener.add(new RefreshMetricUpdater(refreshMetric));
         if (this.checkpointPublisher != null && shardRouting.primary() && indexSettings.isSegRepLocalEnabled()) {
             internalRefreshListener.add(new CheckpointRefreshListener(this, this.checkpointPublisher));