fix: Avoid blocking thread in AsyncResultSet

Author: sakthivelmanii

google-cloud-spanner/clirr-ignored-differences.xml

@@ -790,5 +790,9 @@
     <className>com/google/cloud/spanner/connection/Connection</className>
     <method>boolean isAutoBatchDmlUpdateCountVerification()</method>
   </difference>
-  
+  <difference>
+    <differenceType>7012</differenceType>
+    <className>com/google/cloud/spanner/ResultSet</className>
+    <method>boolean initiateStreaming(com.google.cloud.spanner.AsyncResultSet$StreamMessageListener)</method>
+  </difference>
 </differences>

google-cloud-spanner/src/main/java/com/google/cloud/spanner/AbstractReadContext.java

@@ -768,8 +768,9 @@ ResultSet executeQueryInternalWithOptions(
             rpc.getExecuteQueryRetrySettings(),
             rpc.getExecuteQueryRetryableCodes()) {
           @Override
-          CloseableIterator<PartialResultSet> startStream(@Nullable ByteString resumeToken,
-                                                          AsyncResultSet.StreamMessageListener streamListener) {
+          CloseableIterator<PartialResultSet> startStream(
+              @Nullable ByteString resumeToken,
+              AsyncResultSet.StreamMessageListener streamListener) {
             GrpcStreamIterator stream =
                 new GrpcStreamIterator(statement, prefetchChunks, cancelQueryWhenClientIsClosed);
             stream.registerListener(streamListener);
@@ -961,8 +962,9 @@ ResultSet readInternalWithOptions(
             rpc.getReadRetrySettings(),
             rpc.getReadRetryableCodes()) {
           @Override
-          CloseableIterator<PartialResultSet> startStream(@Nullable ByteString resumeToken,
-                                                          AsyncResultSet.StreamMessageListener streamListener) {
+          CloseableIterator<PartialResultSet> startStream(
+              @Nullable ByteString resumeToken,
+              AsyncResultSet.StreamMessageListener streamListener) {
             GrpcStreamIterator stream =
                 new GrpcStreamIterator(prefetchChunks, cancelQueryWhenClientIsClosed);
             stream.registerListener(streamListener);

google-cloud-spanner/src/main/java/com/google/cloud/spanner/AsyncResultSet.java

@@ -19,7 +19,6 @@
 import com.google.api.core.ApiFuture;
 import com.google.common.base.Function;
 import com.google.spanner.v1.PartialResultSet;
-
 import java.util.List;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
@@ -227,16 +226,20 @@ interface ReadyCallback {
   <T> List<T> toList(Function<StructReader, T> transformer) throws SpannerException;
 
   /**
-   * An interface to register the listener for streaming gRPC request. It will be called when a chunk is received
-   * from gRPC streaming call.
+   * An interface to register the listener for streaming gRPC request. It will be called when a
+   * chunk is received from gRPC streaming call.
    */
   interface StreamMessageListener {
-    void onStreamMessage(PartialResultSet partialResultSet, int prefetchChunks, int currentBufferSize, StreamMessageRequestor streamMessageRequestor);
+    void onStreamMessage(
+        PartialResultSet partialResultSet,
+        int prefetchChunks,
+        int currentBufferSize,
+        StreamMessageRequestor streamMessageRequestor);
   }
 
   /**
-   * An interface to request more messages from the gRPC streaming call. It will be implemented by the class which has access
-   * to SpannerRpc.StreamingCall object
+   * An interface to request more messages from the gRPC streaming call. It will be implemented by
+   * the class which has access to SpannerRpc.StreamingCall object
    */
   interface StreamMessageRequestor {
     void requestMessages(int numOfMessages);

google-cloud-spanner/src/main/java/com/google/cloud/spanner/AsyncResultSetImpl.java

@@ -31,7 +31,6 @@
 import com.google.spanner.v1.PartialResultSet;
 import com.google.spanner.v1.ResultSetMetadata;
 import com.google.spanner.v1.ResultSetStats;
-
 import java.util.Collection;
 import java.util.LinkedList;
 import java.util.List;
@@ -40,10 +39,10 @@
 import java.util.logging.Logger;
 
 /** Default implementation for {@link AsyncResultSet}. */
-class AsyncResultSetImpl extends ForwardingStructReader implements ListenableAsyncResultSet, AsyncResultSet.StreamMessageListener {
+class AsyncResultSetImpl extends ForwardingStructReader
+    implements ListenableAsyncResultSet, AsyncResultSet.StreamMessageListener {
   private static final Logger log = Logger.getLogger(AsyncResultSetImpl.class.getName());
 
-
   /** State of an {@link AsyncResultSetImpl}. */
   private enum State {
     INITIALIZED,
@@ -458,7 +457,7 @@ private class InitiateStreamingRunnable implements Runnable {
     @Override
     public void run() {
       try {
-        if(!initiateStreaming(AsyncResultSetImpl.this)) {
+        if (!initiateStreaming(AsyncResultSetImpl.this)) {
           initiateProduceRows();
         }
       } catch (SpannerException e) {
@@ -504,7 +503,6 @@ public void cancel() {
           "cannot cancel a result set without a callback");
       state = State.CANCELLED;
       pausedLatch.countDown();
-      this.result.setException(CANCELLED_EXCEPTION);
     }
   }
 
@@ -625,14 +623,21 @@ public Struct getCurrentRowAsStruct() {
   }
 
   @Override
-  public void onStreamMessage(PartialResultSet partialResultSet, int prefetchChunks, int currentBufferSize, StreamMessageRequestor streamMessageRequestor) {
+  public void onStreamMessage(
+      PartialResultSet partialResultSet,
+      int prefetchChunks,
+      int currentBufferSize,
+      StreamMessageRequestor streamMessageRequestor) {
     synchronized (monitor) {
       if (state == State.IN_PROGRESS) {
-        // if PartialResultSet contains resume token or buffer size is more than configured size or we have reached
+        // if PartialResultSet contains resume token or buffer size is more than configured size or
+        // we have reached
         // end of stream, we can start the thread
-        boolean startJobThread = !partialResultSet.getResumeToken().isEmpty()
-                || currentBufferSize > prefetchChunks || partialResultSet == GrpcStreamIterator.END_OF_STREAM;
-        if (startJobThread){
+        boolean startJobThread =
+            !partialResultSet.getResumeToken().isEmpty()
+                || currentBufferSize > prefetchChunks
+                || partialResultSet == GrpcStreamIterator.END_OF_STREAM;
+        if (startJobThread) {
           initiateProduceRows();
         } else {
           streamMessageRequestor.requestMessages(1);

google-cloud-spanner/src/main/java/com/google/cloud/spanner/ForwardingResultSet.java

@@ -105,6 +105,6 @@ public ResultSetMetadata getMetadata() {
 
   @Override
   public boolean initiateStreaming(AsyncResultSet.StreamMessageListener streamMessageListener) {
-      return delegate.get().initiateStreaming(streamMessageListener);
+    return delegate.get().initiateStreaming(streamMessageListener);
   }
 }

google-cloud-spanner/src/main/java/com/google/cloud/spanner/GrpcStreamIterator.java

@@ -23,15 +23,14 @@
 import com.google.common.collect.AbstractIterator;
 import com.google.common.util.concurrent.Uninterruptibles;
 import com.google.spanner.v1.PartialResultSet;
-import org.threeten.bp.Duration;
-
-import javax.annotation.Nullable;
 import java.util.Optional;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import javax.annotation.Nullable;
+import org.threeten.bp.Duration;
 
 /** Adapts a streaming read/query call into an iterator over partial result sets. */
 @VisibleForTesting
@@ -199,7 +198,7 @@ public boolean cancelQueryWhenClientIsClosed() {
   }
 
   private void onStreamMessage(PartialResultSet partialResultSet) {
-    Optional.ofNullable(streamMessageListener).ifPresent(
-            sl -> sl.onStreamMessage(partialResultSet, prefetchChunks, stream.size(), this));
+    Optional.ofNullable(streamMessageListener)
+        .ifPresent(sl -> sl.onStreamMessage(partialResultSet, prefetchChunks, stream.size(), this));
   }
 }

google-cloud-spanner/src/main/java/com/google/cloud/spanner/ResultSet.java

@@ -83,6 +83,10 @@ default ResultSetMetadata getMetadata() {
     throw new UnsupportedOperationException("Method should be overridden");
   }
 
+  /**
+   * Returns the {@link boolean} for this {@link ResultSet}. This method will be used by AsyncResultSet
+   * to initiate gRPC streaming
+   */
   default boolean initiateStreaming(AsyncResultSet.StreamMessageListener streamMessageListener) {
     return false;
   }

google-cloud-spanner/src/main/java/com/google/cloud/spanner/ResumableStreamIterator.java

@@ -16,6 +16,11 @@
 
 package com.google.cloud.spanner;
 
+import static com.google.cloud.spanner.SpannerExceptionFactory.newSpannerException;
+import static com.google.cloud.spanner.SpannerExceptionFactory.newSpannerExceptionForCancellation;
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import com.google.api.client.util.BackOff;
 import com.google.api.client.util.ExponentialBackOff;
 import com.google.api.gax.grpc.GrpcStatusCode;
@@ -30,8 +35,6 @@
 import com.google.spanner.v1.PartialResultSet;
 import io.grpc.Context;
 import io.opentelemetry.api.common.Attributes;
-
-import javax.annotation.Nullable;
 import java.io.IOException;
 import java.util.LinkedList;
 import java.util.Objects;
@@ -41,11 +44,7 @@
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-
-import static com.google.cloud.spanner.SpannerExceptionFactory.newSpannerException;
-import static com.google.cloud.spanner.SpannerExceptionFactory.newSpannerExceptionForCancellation;
-import static com.google.common.base.Preconditions.checkArgument;
-import static com.google.common.base.Preconditions.checkNotNull;
+import javax.annotation.Nullable;
 
 /**
  * Wraps an iterator over partial result sets, supporting resuming RPCs on error. This class keeps
@@ -198,8 +197,8 @@ public void execute(Runnable command) {
     }
   }
 
-  abstract CloseableIterator<PartialResultSet> startStream(@Nullable ByteString resumeToken,
-                                                           AsyncResultSet.StreamMessageListener streamMessageListener);
+  abstract CloseableIterator<PartialResultSet> startStream(
+      @Nullable ByteString resumeToken, AsyncResultSet.StreamMessageListener streamMessageListener);
 
   /**
    * Prepares the iterator for a retry on a different gRPC channel. Returns true if that is
@@ -318,9 +317,9 @@ && prepareIteratorForRetryOnDifferentGrpcChannel()) {
   private void eagerStartStreaming() {
     if (stream == null) {
       span.addAnnotation(
-              "Starting/Resuming stream",
-              "ResumeToken",
-              resumeToken == null ? "null" : resumeToken.toStringUtf8());
+          "Starting/Resuming stream",
+          "ResumeToken",
+          resumeToken == null ? "null" : resumeToken.toStringUtf8());
       try (IScope scope = tracer.withSpan(span)) {
         // When start a new stream set the Span as current to make the gRPC Span a child of
         // this Span.

google-cloud-spanner/src/main/java/com/google/cloud/spanner/SessionPool.java

@@ -289,7 +289,8 @@ public boolean next() throws SpannerException {
         }
 
         @Override
-        public boolean initiateStreaming(AsyncResultSet.StreamMessageListener streamMessageListener) {
+        public boolean initiateStreaming(
+            AsyncResultSet.StreamMessageListener streamMessageListener) {
           try {
             boolean ret = super.initiateStreaming(streamMessageListener);
             if (beforeFirst) {

google-cloud-spanner/src/test/java/com/google/cloud/spanner/AsyncResultSetImplTest.java

@@ -48,8 +48,6 @@
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
-import org.mockito.Mock;
-import org.mockito.Mockito;
 import org.mockito.invocation.InvocationOnMock;
 import org.mockito.stubbing.Answer;