From 7c8fdcd1b60e6f5e7f9689ae320526fee1bfdb91 Mon Sep 17 00:00:00 2001
From: Andrzej Bialecki <ab@apache.org>
Date: Mon, 21 May 2018 12:12:14 +0200
Subject: [PATCH] Fix test that assumed the absence of thread context switch
 between calls.

---
 .../apache/solr/common/util/TimeSource.java   | 21 +++++++++++++++++++
 .../solr/common/util/TestTimeSource.java      | 19 ++++++++++-------
 2 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/solr/solrj/src/java/org/apache/solr/common/util/TimeSource.java b/solr/solrj/src/java/org/apache/solr/common/util/TimeSource.java
index d7b5b783238..69aa40ff6a4 100644
--- a/solr/solrj/src/java/org/apache/solr/common/util/TimeSource.java
+++ b/solr/solrj/src/java/org/apache/solr/common/util/TimeSource.java
@@ -51,6 +51,12 @@ public abstract class TimeSource {
       return getTimeNs();
     }
 
+    @Override
+    long[] getTimeAndEpochNs() {
+      long time = getTimeNs();
+      return new long[] {time, time};
+    }
+
     @Override
     public void sleep(long ms) throws InterruptedException {
       Thread.sleep(ms);
@@ -87,6 +93,12 @@ public abstract class TimeSource {
       return epochStart + getTimeNs() - nanoStart;
     }
 
+    @Override
+    long[] getTimeAndEpochNs() {
+      long time = getTimeNs();
+      return new long[] {time, epochStart + time - nanoStart};
+    }
+
     @Override
     public void sleep(long ms) throws InterruptedException {
       Thread.sleep(ms);
@@ -125,6 +137,12 @@ public abstract class TimeSource {
       return epochStart + getTimeNs() - nanoStart;
     }
 
+    @Override
+    long[] getTimeAndEpochNs() {
+      long time = getTimeNs();
+      return new long[] {time, epochStart + time - nanoStart};
+    }
+
     @Override
     public void sleep(long ms) throws InterruptedException {
       ms = Math.round((double)ms / multiplier);
@@ -198,6 +216,9 @@ public abstract class TimeSource {
    */
   public abstract long getEpochTimeNs();
 
+  // for unit testing
+  abstract long[] getTimeAndEpochNs();
+
   /**
    * Sleep according to this source's notion of time. Eg. accelerated time source such as
    * {@link SimTimeSource} will sleep proportionally shorter, according to its multiplier.
diff --git a/solr/solrj/src/test/org/apache/solr/common/util/TestTimeSource.java b/solr/solrj/src/test/org/apache/solr/common/util/TestTimeSource.java
index a6cfb68fa8e..ad38a837a2b 100644
--- a/solr/solrj/src/test/org/apache/solr/common/util/TestTimeSource.java
+++ b/solr/solrj/src/test/org/apache/solr/common/util/TestTimeSource.java
@@ -33,8 +33,13 @@ public class TestTimeSource extends SolrTestCaseJ4 {
   }
 
   private void doTestEpochTime(TimeSource ts) throws Exception {
-    long prevTime = ts.getTimeNs();
-    long prevEpochTime = ts.getEpochTimeNs();
+
+    // XXX the method below doesn't work reliably because
+    // XXX there could be a long thread context switch between these two calls:
+    // long prevTime = ts.getTimeNs();
+    // long prevEpochTime = ts.getEpochTimeNs();
+
+    long[] prevTimeAndEpoch = ts.getTimeAndEpochNs();
     long delta = 500000000; // 500 ms
     long maxDiff = 200000;
     if (ts instanceof TimeSource.SimTimeSource) {
@@ -42,14 +47,12 @@ public class TestTimeSource extends SolrTestCaseJ4 {
     }
     for (int i = 0; i < 10; i++) {
       ts.sleep(500);
-      long curTime = ts.getTimeNs();
-      long curEpochTime = ts.getEpochTimeNs();
-      long diff = prevTime + delta - curTime;
+      long[] curTimeAndEpoch = ts.getTimeAndEpochNs();
+      long diff = prevTimeAndEpoch[0] + delta - curTimeAndEpoch[0];
       assertTrue(ts + " time diff=" + diff, diff < maxDiff);
-      diff = prevEpochTime + delta - curEpochTime;
+      diff = prevTimeAndEpoch[1] + delta - curTimeAndEpoch[1];
       assertTrue(ts + " epochTime diff=" + diff, diff < maxDiff);
-      prevTime = curTime;
-      prevEpochTime = curEpochTime;
+      prevTimeAndEpoch = curTimeAndEpoch;
     }
   }
 }