#194: Some java client wait APIs could incorrectly exit due to overflow.

Summary: When the passed in timeout was maximum long value, the summation was hitting errors. Made it a subtraction at couple of places.

Test Plan:
Added unit test.

Jenkins

Reviewers: bogdan

Reviewed By: bogdan

Subscribers: ybase

Differential Revision: https://phabricator.dev.yugabyte.com/D4643

java/yb-client/src/main/java/org/yb/client/YBClient.java

@@ -91,6 +91,10 @@ public class YBClient implements AutoCloseable {
   // Log info after these many iterations.
   private static final int LOG_EVERY_NUM_ITERS = 200;
 
+  // Simple way to inject an error on Wait based APIs. If enabled, after first inject,
+  // it will be turned off. We can enhance it to use more options like every-N etc.
+  private boolean injectWaitError = false;
+
   public YBClient(AsyncYBClient asyncClient) {
     this.asyncClient = asyncClient;
   }
@@ -450,7 +454,7 @@ private String waitAndGetLeaderMasterUUID(long timeoutMs) throws Exception {
       }
 
       Thread.sleep(asyncClient.SLEEP_TIME);
-    } while (System.currentTimeMillis() < start + timeoutMs);
+    } while (System.currentTimeMillis() - start < timeoutMs);
 
     LOG.error("Timed out getting leader uuid.");
 
@@ -696,6 +700,14 @@ public boolean get() throws Exception {
     }
   }
 
+  /**
+   * Quick and dirty error injection on Wait based API's.
+   * After every use, for now, will get automatically disabled.
+   */
+  public void injectWaitError() {
+    injectWaitError = true;
+  }
+
   /**
    * Helper method that loops on a condition every 500ms until it returns true or the
    * operation times out.
@@ -711,6 +723,13 @@ private boolean waitForCondition(Condition condition, final long timeoutMs) {
     String errorMessage = null;
     do {
       try {
+        if (injectWaitError) {
+          Thread.sleep(AsyncYBClient.SLEEP_TIME);
+          injectWaitError = false;
+          String msg = "Simulated expection due to injected error.";
+          LOG.info(msg);
+          throw new RuntimeException(msg);
+        }
         if (condition.get()) {
           return true;
         }
@@ -737,7 +756,7 @@ private boolean waitForCondition(Condition condition, final long timeoutMs) {
       try {
         Thread.sleep(AsyncYBClient.SLEEP_TIME);
       } catch (Exception e) {}
-    } while (System.currentTimeMillis() < start + timeoutMs);
+    } while (System.currentTimeMillis() - start < timeoutMs);
 
     if (errorMessage == null) {
       LOG.error("Timed out waiting for operation. Final exception was {}.",

java/yb-client/src/test/java/org/yb/client/TestYBClient.java

@@ -112,6 +112,17 @@ public void testClientCreateDestroy() throws Exception {
     }
   }
 
+  /**
+   * Test Waiting for load balance, with simulated errors.
+   * @throws Exception
+   */
+  @Test(timeout = 100000)
+  public void testWaitForLoadBalance() throws Exception {
+    syncClient.injectWaitError();
+    boolean isBalanced = syncClient.waitForLoadBalance(Long.MAX_VALUE, 0);
+    assertTrue(isBalanced);
+  }
+
   /**
    * Test Master Configuration Change operation going from A,B,C to D,E,F.
    * @throws Exception