fixes periodic failure with CompactionIT (apache#4201)

The test CompactionIT.testConcurrentSplit() would periodically fail
because it relied on the old behavior of WaitFor.  Changed the test to
use custom code that waits up to three seconds for a condition to be met
and then continues.

Author: keith-turner

test/src/main/java/org/apache/accumulo/test/functional/CompactionIT.java

@@ -472,12 +472,17 @@ public void testConcurrentSplit() throws Exception {
         splits.add(new Text(String.format("r:%04d", i)));
       }
 
-      // wait a bit for some tablets to have files selected, it possible the compaction have
-      // completed before this so do not wait long
-      Wait.waitFor(
-          () -> countTablets(tableName, tabletMetadata -> tabletMetadata.getSelectedFiles() != null)
-              > 0,
-          3000, 10);
+      // Wait a bit for some tablets to have files selected, it possible the compaction have
+      // completed before this so do not wait long. Once files are selected compactions can start.
+      // This speed bump is an attempt to increase the chance that splits and compactions run
+      // concurrently. Wait.waitFor() is not used here because it will throw an exception if the
+      // time limit is exceeded.
+      long startTime = System.nanoTime();
+      while (System.nanoTime() - startTime < SECONDS.toNanos(3)
+          && countTablets(tableName, tabletMetadata -> tabletMetadata.getSelectedFiles() != null)
+              == 0) {
+        Thread.sleep(10);
+      }
 
       // add 10 more splits to the table
       c.tableOperations().addSplits(tableName, splits);
@@ -487,12 +492,16 @@ public void testConcurrentSplit() throws Exception {
         splits.add(new Text(String.format("r:%04d", i)));
       }
 
-      // wait a bit for some tablets to be compacted, it possible the compaction have completed
-      // before this so do not wait long
-      Wait.waitFor(
-          () -> countTablets(tableName, tabletMetadata -> !tabletMetadata.getCompacted().isEmpty())
-              > 0,
-          3000, 10);
+      // Wait a bit for some tablets to be compacted, it possible the compaction have completed
+      // before this so do not wait long. Wait.waitFor() is not used here because it will throw an
+      // exception if the time limit is exceeded. This is just a speed bump, its ok if the condition
+      // is not met within the time limit.
+      startTime = System.nanoTime();
+      while (System.nanoTime() - startTime < SECONDS.toNanos(3)
+          && countTablets(tableName, tabletMetadata -> !tabletMetadata.getCompacted().isEmpty())
+              == 0) {
+        Thread.sleep(10);
+      }
 
       // add 80 more splits to the table
       c.tableOperations().addSplits(tableName, splits);