LUCENE-6436: add SuppressFsync annotation and reduce the number of fsyncs in tests

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1674570 13f79535-47bb-0310-9956-ffa450edef68

lucene/test-framework/src/java/org/apache/lucene/util/LuceneTestCase.java

@@ -312,6 +312,18 @@ public abstract class LuceneTestCase extends Assert {
     String[] value();
   }
   
+  /**
+   * Annotation for test classes that should avoid always omit
+   * actual fsync calls from reaching the filesystem.
+   * <p>
+   * This can be useful, e.g. if they make many lucene commits.
+   */
+  @Documented
+  @Inherited
+  @Retention(RetentionPolicy.RUNTIME)
+  @Target(ElementType.TYPE)
+  public @interface SuppressFsync {}
+  
   /**
    * Marks any suites which are known not to close all the temporary
    * files. This may prevent temp. files and folders from being cleaned

lucene/test-framework/src/java/org/apache/lucene/util/TestRuleTemporaryFilesCleanup.java

@@ -23,6 +23,7 @@ import org.apache.lucene.mockfile.LeakFS;
 import org.apache.lucene.mockfile.VerboseFS;
 import org.apache.lucene.mockfile.WindowsFS;
 import org.apache.lucene.util.LuceneTestCase.SuppressFileSystems;
+import org.apache.lucene.util.LuceneTestCase.SuppressFsync;
 import org.apache.lucene.util.LuceneTestCase.SuppressTempFileChecks;
 
 import com.carrotsearch.randomizedtesting.RandomizedContext;
@@ -138,11 +139,17 @@ final class TestRuleTemporaryFilesCleanup extends TestRuleAdapter {
     }
     
     Random random = RandomizedContext.current().getRandom();
-    // sometimes just use a bare filesystem
+    
-    if (random.nextInt(10) > 0) {
+    // speed up tests by omitting actual fsync calls to the hardware most of the time.
+    if (targetClass.isAnnotationPresent(SuppressFsync.class) || random.nextInt(100) > 0) {
       if (allowed(avoid, DisableFsyncFS.class)) {
         fs = new DisableFsyncFS(fs).getFileSystem(null);
       }
+    }
+    
+    // otherwise, wrap with mockfilesystems for additional checks. some 
+    // of these have side effects (e.g. concurrency) so it doesn't always happen.
+    if (random.nextInt(10) > 0) {
       if (allowed(avoid, LeakFS.class)) {
         fs = new LeakFS(fs).getFileSystem(null);
       }