JAVA-2815: Add TransientTransactionError error label

Add TransientTransactionError error label for MongoTimeoutException
as required by the specification.  Currently there's no strategy to
test this, as the classes in which it's implemented are not easily
subject to mocking.

Author: jyemin

driver-async/src/main/com/mongodb/async/client/OperationExecutorImpl.java

@@ -20,6 +20,7 @@
 import com.mongodb.MongoException;
 import com.mongodb.MongoInternalException;
 import com.mongodb.MongoSocketException;
+import com.mongodb.MongoTimeoutException;
 import com.mongodb.ReadConcern;
 import com.mongodb.ReadPreference;
 import com.mongodb.async.SingleResultCallback;
@@ -126,7 +127,8 @@ public void onResult(final T result, final Throwable t) {
 
 
     private void labelException(final Throwable t, final ClientSession session) {
-        if (t instanceof MongoSocketException && session != null && session.hasActiveTransaction()
+        if ((t instanceof MongoSocketException || t instanceof MongoTimeoutException)
+                && session != null && session.hasActiveTransaction()
                 && !((MongoException) t).hasErrorLabel(UNKNOWN_TRANSACTION_COMMIT_RESULT_LABEL)) {
             ((MongoException) t).addLabel(TRANSIENT_TRANSACTION_ERROR_LABEL);
         }

driver-sync/src/main/com/mongodb/client/internal/MongoClientDelegate.java

@@ -22,6 +22,7 @@
 import com.mongodb.MongoException;
 import com.mongodb.MongoInternalException;
 import com.mongodb.MongoSocketException;
+import com.mongodb.MongoTimeoutException;
 import com.mongodb.ReadConcern;
 import com.mongodb.ReadPreference;
 import com.mongodb.ServerAddress;
@@ -46,6 +47,7 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import static com.mongodb.MongoException.TRANSIENT_TRANSACTION_ERROR_LABEL;
 import static com.mongodb.MongoException.UNKNOWN_TRANSACTION_COMMIT_RESULT_LABEL;
 import static com.mongodb.ReadPreference.primary;
 import static com.mongodb.assertions.Assertions.isTrue;
@@ -175,7 +177,7 @@ public <T> T execute(final ReadOperation<T> operation, final ReadPreference read
                     throw new MongoClientException("Read preference in a transaction must be primary");
                 }
                 return operation.execute(binding);
-            } catch (MongoSocketException e) {
+            } catch (MongoException e) {
                 labelException(session, e);
                 throw e;
             } finally {
@@ -189,7 +191,7 @@ public <T> T execute(final WriteOperation<T> operation, final ReadConcern readCo
             WriteBinding binding = getWriteBinding(readConcern, actualClientSession, session == null && actualClientSession != null);
             try {
                 return operation.execute(binding);
-            } catch (MongoSocketException e) {
+            } catch (MongoException e) {
                 labelException(session, e);
                 throw e;
             } finally {
@@ -217,8 +219,9 @@ ReadWriteBinding getReadWriteBinding(final ReadPreference readPreference, final
         }
 
         private void labelException(final @Nullable ClientSession session, final MongoException e) {
-            if (session != null && session.hasActiveTransaction() && !e.hasErrorLabel(UNKNOWN_TRANSACTION_COMMIT_RESULT_LABEL)) {
-                e.addLabel(MongoException.TRANSIENT_TRANSACTION_ERROR_LABEL);
+            if ((e instanceof MongoSocketException || e instanceof MongoTimeoutException)
+                    && session != null && session.hasActiveTransaction() && !e.hasErrorLabel(UNKNOWN_TRANSACTION_COMMIT_RESULT_LABEL)) {
+                e.addLabel(TRANSIENT_TRANSACTION_ERROR_LABEL);
             }
         }