feat: improve batching summary errors

gax-java/gax/src/main/java/com/google/api/gax/batching/BatcherStats.java

@@ -31,7 +31,9 @@
 
 import com.google.api.gax.rpc.ApiException;
 import com.google.api.gax.rpc.StatusCode.Code;
+import com.google.common.base.Joiner;
 import com.google.common.base.MoreObjects;
+import com.google.common.collect.EvictingQueue;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
@@ -52,6 +54,9 @@ class BatcherStats {
   private final Map<Class, Integer> entryExceptionCounts = new HashMap<>();
   private final Map<Code, Integer> entryStatusCounts = new HashMap<>();
 
+  private final EvictingQueue<String> sampleOfRpcErrors = EvictingQueue.create(Integer.getInteger("com.google.api.gax.batching.errors.max-samples", 50));
+  private final EvictingQueue<String> sampleOfEntryErrors = EvictingQueue.create(Integer.getInteger("com.google.api.gax.batching.errors.max-samples", 50));
+
   /**
    * Records the count of the exception and it's type when a complete batch failed to apply.
    *
@@ -69,6 +74,8 @@ synchronized void recordBatchFailure(Throwable throwable) {
       requestStatusCounts.put(code, oldStatusCount + 1);
     }
 
+    sampleOfRpcErrors.add(throwable.toString());
+
     int oldExceptionCount = MoreObjects.firstNonNull(requestExceptionCounts.get(exceptionClass), 0);
     requestExceptionCounts.put(exceptionClass, oldExceptionCount + 1);
   }
@@ -96,6 +103,8 @@ synchronized <T extends BatchEntry> void recordBatchElementsCompletion(
         Throwable actualCause = throwable.getCause();
         Class exceptionClass = actualCause.getClass();
 
+        sampleOfEntryErrors.add(actualCause.toString());
+
         if (actualCause instanceof ApiException) {
           Code code = ((ApiException) actualCause).getStatusCode().getCode();
           exceptionClass = ApiException.class;
@@ -144,6 +153,17 @@ synchronized BatchingException asException() {
           .append(buildExceptionList(entryExceptionCounts, entryStatusCounts))
           .append(".");
     }
+
+    if (!sampleOfRpcErrors.isEmpty()) {
+      messageBuilder.append(" Sample of RPC errors: ");
+      messageBuilder.append(Joiner.on(", ").join(sampleOfRpcErrors));
+      messageBuilder.append(".");
+    }
+    if (!sampleOfEntryErrors.isEmpty()) {
+      messageBuilder.append(" Sample of entry errors: ");
+      messageBuilder.append(Joiner.on(", ").join(sampleOfEntryErrors));
+      messageBuilder.append(".");
+    }
     return new BatchingException(messageBuilder.toString());
   }
 

gax-java/gax/src/test/java/com/google/api/gax/batching/BatcherStatsTest.java

@@ -55,7 +55,7 @@ public void testRequestFailuresOnly() {
 
     batcherStats.recordBatchFailure(
         ApiExceptionFactory.createException(
-            new RuntimeException(), FakeStatusCode.of(StatusCode.Code.INVALID_ARGUMENT), false));
+            "fake api error", new RuntimeException(), FakeStatusCode.of(StatusCode.Code.INVALID_ARGUMENT), false));
 
     batcherStats.recordBatchFailure(new RuntimeException("Request failed"));
 
@@ -65,6 +65,8 @@ public void testRequestFailuresOnly() {
     assertThat(exception).hasMessageThat().contains("1 RuntimeException");
     assertThat(exception).hasMessageThat().contains("1 ApiException(1 INVALID_ARGUMENT)");
     assertThat(exception).hasMessageThat().contains("and 0 partial failures.");
+    assertThat(exception).hasMessageThat().contains("com.google.api.gax.rpc.InvalidArgumentException: fake api error, java.lang.RuntimeException: Request failed.");
+
   }
 
   @Test
@@ -79,7 +81,7 @@ public void testEntryFailureOnly() {
     SettableApiFuture<Integer> batchTwoResult = SettableApiFuture.create();
     batchTwoResult.setException(
         ApiExceptionFactory.createException(
-            new RuntimeException(), FakeStatusCode.of(StatusCode.Code.UNAVAILABLE), false));
+            "fake entry error", new RuntimeException(), FakeStatusCode.of(StatusCode.Code.UNAVAILABLE), false));
     batcherStats.recordBatchElementsCompletion(
         ImmutableList.of(BatchEntry.create(2, batchTwoResult)));
 
@@ -89,6 +91,7 @@ public void testEntryFailureOnly() {
         .contains("The 2 partial failures contained 2 entries that failed with:");
     assertThat(ex).hasMessageThat().contains("1 ApiException(1 UNAVAILABLE)");
     assertThat(ex).hasMessageThat().contains("1 IllegalStateException");
+    assertThat(ex).hasMessageThat().contains("Sample of entry errors: java.lang.IllegalStateException: local element failure, com.google.api.gax.rpc.UnavailableException: fake entry error.");
   }
 
   @Test
@@ -110,6 +113,8 @@ public void testRequestAndEntryFailures() {
         .contains(
             "Batching finished with 1 batches failed to apply due to: 1 RuntimeException and 1 "
                 + "partial failures. The 1 partial failures contained 1 entries that failed with:"
-                + " 1 ApiException(1 ALREADY_EXISTS).");
+                + " 1 ApiException(1 ALREADY_EXISTS)."
+                + " Sample of RPC errors: java.lang.RuntimeException: Batch failure."
+                + " Sample of entry errors: com.google.api.gax.rpc.AlreadyExistsException: java.lang.RuntimeException.");
   }
 }