Allow retrying a timed-out query if it does not do writes

The current query driver logic disables retrying a query request if it gets a non-retryable error. But a TimeoutException (or RequestTimeoutException) should allow a retry if the query does not do writes. This change fixes this specific case. Retries will be allowed only if the query already is prepared and the prepare statement does not do writes.

Author: connelly38

CHANGELOG.md

@@ -2,6 +2,11 @@
 All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/).
 
+## [Unreleased]
+
+### Changed
+- Allow application to retry a QueryRequest if it gets a timeout exception and the query only does reads
+
 ## [5.3.6] 2022-08-23
 
 ### Added

driver/src/main/java/oracle/nosql/driver/query/QueryDriver.java

@@ -8,8 +8,10 @@
 package oracle.nosql.driver.query;
 
 import java.util.ArrayList;
+import java.util.concurrent.TimeoutException;
 
 import oracle.nosql.driver.NoSQLException;
+import oracle.nosql.driver.RequestTimeoutException;
 import oracle.nosql.driver.RetryableException;
 import oracle.nosql.driver.http.Client;
 import oracle.nosql.driver.ops.PreparedStatement;
@@ -178,7 +180,7 @@ public void compute(QueryResult result) {
              * If it's not a retryable exception, save it so that we throw it
              * again if the app resubmits the QueryRequest.
              */
-            if (!(e instanceof RetryableException)) {
+            if (!isRetryableException(e)) {
                 theError = new NoSQLException(
                     "QueryRequest cannot be continued after throwing a " +
                     "non-retryable exception in a previous execution. " +
@@ -208,6 +210,23 @@ public void compute(QueryResult result) {
         theRequest.setContKey(theContinuationKey);
     }
 
+    private boolean isRetryableException(Throwable e) {
+        if (e instanceof RetryableException) {
+            return true;
+        }
+        /*
+         * if we got a timeout, and the query does not do writes, allow
+         * retrying
+         */
+       if (((e instanceof TimeoutException) ||
+           (e instanceof RequestTimeoutException)) &&
+           theRequest != null && theRequest.getPreparedStatement() != null &&
+           theRequest.getPreparedStatement().doesWrites() == false) {
+           return true;
+       }
+       return false;
+    }
+
     private void setQueryResult(QueryResult result) {
 
         result.setResults(theResults);