HBASE-18587 Fix flaky TestFileIOEngine

This short circuits reads and writes with 0 length and also removes flakiness in TestFileIOEngine

Signed-off-by: Michael Stack <stack@apache.org>

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/FileIOEngine.java

@@ -33,6 +33,7 @@ import org.apache.hadoop.hbase.io.hfile.CacheableDeserializer;
 import org.apache.hadoop.hbase.io.hfile.Cacheable.MemoryType;
 import org.apache.hadoop.hbase.nio.ByteBuff;
 import org.apache.hadoop.hbase.nio.SingleByteBuff;
+import org.apache.hadoop.hbase.shaded.com.google.common.base.Preconditions;
 import org.apache.hadoop.util.StringUtils;
 
 /**
@@ -122,7 +123,9 @@ public class FileIOEngine implements IOEngine {
   @Override
   public Cacheable read(long offset, int length, CacheableDeserializer<Cacheable> deserializer)
       throws IOException {
+    Preconditions.checkArgument(length >= 0, "Length of read can not be less than 0.");
     ByteBuffer dstBuffer = ByteBuffer.allocate(length);
+    if (length != 0) {
       accessFile(readAccessor, dstBuffer, offset);
       // The buffer created out of the fileChannel is formed by copying the data from the file
       // Hence in this case there is no shared memory that we point to. Even if the BucketCache evicts
@@ -132,6 +135,7 @@ public class FileIOEngine implements IOEngine {
         throw new RuntimeException("Only " + dstBuffer.limit() + " bytes read, " + length
             + " expected");
       }
+    }
     return deserializer.deserialize(new SingleByteBuff(dstBuffer), true, MemoryType.EXCLUSIVE);
   }
 
@@ -143,6 +147,9 @@ public class FileIOEngine implements IOEngine {
    */
   @Override
   public void write(ByteBuffer srcBuffer, long offset) throws IOException {
+    if (!srcBuffer.hasRemaining()) {
+      return;
+    }
     accessFile(writeAccessor, srcBuffer, offset);
   }
 

hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/bucket/TestFileIOEngine.java

@@ -18,6 +18,7 @@
  */
 package org.apache.hadoop.hbase.io.hfile.bucket;
 
+import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertTrue;
 
 import java.io.File;
@@ -30,6 +31,8 @@ import org.apache.hadoop.hbase.io.hfile.bucket.TestByteBufferIOEngine.BufferGrab
 import org.apache.hadoop.hbase.nio.ByteBuff;
 import org.apache.hadoop.hbase.testclassification.IOTests;
 import org.apache.hadoop.hbase.testclassification.SmallTests;
+import org.junit.After;
+import org.junit.Before;
 import org.junit.Test;
 import org.junit.experimental.categories.Category;
 
@@ -38,31 +41,52 @@ import org.junit.experimental.categories.Category;
  */
 @Category({IOTests.class, SmallTests.class})
 public class TestFileIOEngine {
+
+  private static final long TOTAL_CAPACITY = 6 * 1024 * 1024; // 6 MB
+  private static final String[] FILE_PATHS = {"testFileIOEngine1", "testFileIOEngine2",
+      "testFileIOEngine3"};
+  private static final long SIZE_PER_FILE = TOTAL_CAPACITY / FILE_PATHS.length; // 2 MB per File
+  private final static List<Long> boundaryStartPositions = new ArrayList<Long>();
+  private final static List<Long> boundaryStopPositions = new ArrayList<Long>();
+
+  private FileIOEngine fileIOEngine;
+
+  static {
+    boundaryStartPositions.add(0L);
+    for (int i = 1; i < FILE_PATHS.length; i++) {
+      boundaryStartPositions.add(SIZE_PER_FILE * i - 1);
+      boundaryStartPositions.add(SIZE_PER_FILE * i);
+      boundaryStartPositions.add(SIZE_PER_FILE * i + 1);
+    }
+    for (int i = 1; i < FILE_PATHS.length; i++) {
+      boundaryStopPositions.add(SIZE_PER_FILE * i - 1);
+      boundaryStopPositions.add(SIZE_PER_FILE * i);
+      boundaryStopPositions.add(SIZE_PER_FILE * i + 1);
+    }
+    boundaryStopPositions.add(SIZE_PER_FILE * FILE_PATHS.length - 1);
+  }
+
+  @Before
+  public void setUp() throws IOException {
+    fileIOEngine = new FileIOEngine(TOTAL_CAPACITY, false, FILE_PATHS);
+  }
+
+  @After
+  public void cleanUp() {
+    fileIOEngine.shutdown();
+    for (String filePath : FILE_PATHS) {
+      File file = new File(filePath);
+      if (file.exists()) {
+        file.delete();
+      }
+    }
+  }
+
   @Test
   public void testFileIOEngine() throws IOException {
-    long totalCapacity = 6 * 1024 * 1024; // 6 MB
-    String[] filePaths = { "testFileIOEngine1", "testFileIOEngine2",
-        "testFileIOEngine3" };
-    long sizePerFile = totalCapacity / filePaths.length; // 2 MB per File
-    List<Long> boundaryStartPositions = new ArrayList<Long>();
-    boundaryStartPositions.add(0L);
-    for (int i = 1; i < filePaths.length; i++) {
-      boundaryStartPositions.add(sizePerFile * i - 1);
-      boundaryStartPositions.add(sizePerFile * i);
-      boundaryStartPositions.add(sizePerFile * i + 1);
-    }
-    List<Long> boundaryStopPositions = new ArrayList<Long>();
-    for (int i = 1; i < filePaths.length; i++) {
-      boundaryStopPositions.add(sizePerFile * i - 1);
-      boundaryStopPositions.add(sizePerFile * i);
-      boundaryStopPositions.add(sizePerFile * i + 1);
-    }
-    boundaryStopPositions.add(sizePerFile * filePaths.length - 1);
-    FileIOEngine fileIOEngine = new FileIOEngine(totalCapacity, false, filePaths);
-    try {
     for (int i = 0; i < 500; i++) {
-        int len = (int) Math.floor(Math.random() * 100);
+      int len = (int) Math.floor(Math.random() * 100) + 1;
-        long offset = (long) Math.floor(Math.random() * totalCapacity % (totalCapacity - len));
+      long offset = (long) Math.floor(Math.random() * TOTAL_CAPACITY % (TOTAL_CAPACITY - len));
       if (i < boundaryStartPositions.size()) {
         // make the boundary start positon
         offset = boundaryStartPositions.get(i);
@@ -71,7 +95,7 @@ public class TestFileIOEngine {
         offset = boundaryStopPositions.get(i - boundaryStartPositions.size()) - len + 1;
       } else if (i % 2 == 0) {
         // make the cross-files block writing/reading
-          offset = Math.max(1, i % filePaths.length) * sizePerFile - len / 2;
+        offset = Math.max(1, i % FILE_PATHS.length) * SIZE_PER_FILE - len / 2;
       }
       byte[] data1 = new byte[len];
       for (int j = 0; j < data1.length; ++j) {
@@ -81,19 +105,18 @@ public class TestFileIOEngine {
       BufferGrabbingDeserializer deserializer = new BufferGrabbingDeserializer();
       fileIOEngine.read(offset, len, deserializer);
       ByteBuff data2 = deserializer.getDeserializedByteBuff();
-        for (int j = 0; j < data1.length; ++j) {
+      assertArrayEquals(data1, data2.array());
-          assertTrue(data1[j] == data2.get(j));
-        }
-      }
-    } finally {
-      fileIOEngine.shutdown();
-      for (String filePath : filePaths) {
-        File file = new File(filePath);
-        if (file.exists()) {
-          file.delete();
-        }
     }
   }
 
+  @Test
+  public void testFileIOEngineHandlesZeroLengthInput() throws IOException {
+    byte[] data1 = new byte[0];
+
+    fileIOEngine.write(ByteBuffer.wrap(data1), 0);
+    BufferGrabbingDeserializer deserializer = new BufferGrabbingDeserializer();
+    fileIOEngine.read(0, 0, deserializer);
+    ByteBuff data2 = deserializer.getDeserializedByteBuff();
+    assertArrayEquals(data1, data2.array());
   }
 }