fix: Avoid setting error on response future twice (#261)

* fix:Avoid setting error to future twice

	modified:   google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1alpha2/StreamWriter.java

* test fix

google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1alpha2/StreamWriter.java

@@ -250,10 +250,15 @@ public ApiFuture<AppendRowsResponse> append(AppendRowsRequest message) {
    * @throws IOException
    */
   public void refreshAppend() throws IOException, InterruptedException {
+    LOG.info("Establish a write connection.");
     synchronized (this) {
-      Preconditions.checkState(!shutdown.get(), "Cannot shut down on a shut-down writer.");
+      if (shutdown.get()) {
+        LOG.warning("Cannot refresh on a already shutdown writer.");
+        return;
+      }
       // There could be a moment, stub is not yet initialized.
       if (clientStream != null) {
+        LOG.info("Closing the stream");
         clientStream.closeSend();
       }
       messagesBatch.resetAttachSchema();
@@ -348,13 +353,15 @@ private static final class InflightBatch {
     final List<AppendRequestAndFutureResponse> inflightRequests;
     // A list tracks expected offset for each AppendRequest. Used to reconstruct the Response
     // future.
-    final ArrayList<Long> offsetList;
-    final long creationTime;
-    int attempt;
-    long batchSizeBytes;
-    long expectedOffset;
-    Boolean attachSchema;
-    String streamName;
+    private final ArrayList<Long> offsetList;
+    private final long creationTime;
+    private int attempt;
+    private long batchSizeBytes;
+    private long expectedOffset;
+    private Boolean attachSchema;
+    private String streamName;
+
+    private final AtomicBoolean failed;
 
     InflightBatch(
         List<AppendRequestAndFutureResponse> inflightRequests,
@@ -376,6 +383,7 @@ private static final class InflightBatch {
       this.batchSizeBytes = batchSizeBytes;
       this.attachSchema = attachSchema;
       this.streamName = streamName;
+      this.failed = new AtomicBoolean(false);
     }
 
     int count() {
@@ -417,6 +425,13 @@ private AppendRowsRequest getMergedRequest() throws IllegalStateException {
     }
 
     private void onFailure(Throwable t) {
+      if (failed.getAndSet(true)) {
+        // Error has been set already.
+        LOG.warning("Ignore " + t.toString() + " since error has already been set");
+        return;
+      } else {
+        LOG.fine("Setting " + t.toString() + " on response");
+      }
       for (AppendRequestAndFutureResponse request : inflightRequests) {
         request.appendResult.setException(t);
       }
@@ -838,8 +853,10 @@ public void onError(Throwable t) {
           }
           inflightBatch.onFailure(t);
           try {
-            // Establish a new connection.
-            streamWriter.refreshAppend();
+            if (!streamWriter.shutdown.get()) {
+              // Establish a new connection.
+              streamWriter.refreshAppend();
+            }
           } catch (IOException | InterruptedException e) {
             LOG.info("Failed to establish a new connection");
           }

google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1alpha2/StreamWriterTest.java

@@ -424,18 +424,25 @@ public void testFlowControlBehaviorException() throws Exception {
                             .build())
                     .build())
             .build()) {
+      assertEquals(
+          1L,
+          writer
+              .getBatchingSettings()
+              .getFlowControlSettings()
+              .getMaxOutstandingElementCount()
+              .longValue());
 
       testBigQueryWrite.addResponse(AppendRowsResponse.newBuilder().setOffset(1L).build());
+      testBigQueryWrite.setResponseDelay(Duration.ofSeconds(10));
       ApiFuture<AppendRowsResponse> appendFuture1 = sendTestMessage(writer, new String[] {"A"});
       ApiFuture<AppendRowsResponse> appendFuture2 = sendTestMessage(writer, new String[] {"B"});
+      // Wait is necessary for response to be scheduled before timer is advanced.
+      Thread.sleep(5000L);
+      fakeExecutor.advanceTime(Duration.ofSeconds(10));
       try {
         appendFuture2.get();
         Assert.fail("This should fail");
       } catch (Exception e) {
-        if (!e.getMessage().equals("The maximum number of batch elements: 1 have been reached.")) {
-          LOG.info("More error info:");
-          e.printStackTrace();
-        }
         assertEquals(
             "java.util.concurrent.ExecutionException: The maximum number of batch elements: 1 have been reached.",
             e.toString());
@@ -505,6 +512,7 @@ public void testStreamReconnectionExceedRetry() throws Exception {
                     .setMaxAttempts(1)
                     .build())
             .build();
+    assertEquals(1, writer.getRetrySettings().getMaxAttempts());
     StatusRuntimeException transientError = new StatusRuntimeException(Status.UNAVAILABLE);
     testBigQueryWrite.addException(transientError);
     testBigQueryWrite.addException(transientError);
@@ -818,7 +826,7 @@ public void testAwaitTermination() throws Exception {
     testBigQueryWrite.addResponse(AppendRowsResponse.newBuilder().build());
     ApiFuture<AppendRowsResponse> appendFuture1 = sendTestMessage(writer, new String[] {"A"});
     writer.shutdown();
-    assertTrue(writer.awaitTermination(1, TimeUnit.MINUTES));
+    assertTrue(writer.awaitTermination(2, TimeUnit.MINUTES));
   }
 
   @Test