HDFS-6561. org.apache.hadoop.util.DataChecksum should support native checksumming (James Thomas via Colin Patrick McCabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1618680 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -527,6 +527,9 @@ Release 2.6.0 - UNRELEASED
     HADOOP-10335. An ip whilelist based implementation to resolve Sasl
     properties per connection. (Benoy Antony via Arpit Agarwal)
 
+    HDFS-6561. org.apache.hadoop.util.DataChecksum should support native
+    checksumming (James Thomas via Colin Patrick McCabe)
+
   OPTIMIZATIONS
 
     HADOOP-10838. Byte array native checksumming. (James Thomas via todd)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/DataChecksum.java

@@ -390,6 +390,12 @@ public class DataChecksum implements Checksum {
           checksums.array(), checksums.arrayOffset() + checksums.position());
       return;
     }
+
+    if (NativeCrc32.isAvailable()) {
+      NativeCrc32.calculateChunkedSums(bytesPerChecksum, type.id,
+          checksums, data);
+      return;
+    }
     
     data.mark();
     checksums.mark();
@@ -412,10 +418,16 @@ public class DataChecksum implements Checksum {
    * Implementation of chunked calculation specifically on byte arrays. This
    * is to avoid the copy when dealing with ByteBuffers that have array backing.
    */
-  private void calculateChunkedSums(
+  public void calculateChunkedSums(
       byte[] data, int dataOffset, int dataLength,
       byte[] sums, int sumsOffset) {
 
+    if (NativeCrc32.isAvailable()) {
+      NativeCrc32.calculateChunkedSumsByteArray(bytesPerChecksum, type.id,
+          sums, sumsOffset, data, dataOffset, dataLength);
+      return;
+    }
+
     int remaining = dataLength;
     while (remaining > 0) {
       int n = Math.min(remaining, bytesPerChecksum);

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/NativeCrc32.java

@@ -54,33 +54,50 @@ class NativeCrc32 {
   public static void verifyChunkedSums(int bytesPerSum, int checksumType,
       ByteBuffer sums, ByteBuffer data, String fileName, long basePos)
       throws ChecksumException {
-    nativeVerifyChunkedSums(bytesPerSum, checksumType,
+    nativeComputeChunkedSums(bytesPerSum, checksumType,
         sums, sums.position(),
         data, data.position(), data.remaining(),
-        fileName, basePos);
+        fileName, basePos, true);
   }
 
   public static void verifyChunkedSumsByteArray(int bytesPerSum,
       int checksumType, byte[] sums, int sumsOffset, byte[] data,
       int dataOffset, int dataLength, String fileName, long basePos)
       throws ChecksumException {
-    nativeVerifyChunkedSumsByteArray(bytesPerSum, checksumType,
+    nativeComputeChunkedSumsByteArray(bytesPerSum, checksumType,
         sums, sumsOffset,
         data, dataOffset, dataLength,
-        fileName, basePos);
+        fileName, basePos, true);
+  }
+
+  public static void calculateChunkedSums(int bytesPerSum, int checksumType,
+      ByteBuffer sums, ByteBuffer data) {
+    nativeComputeChunkedSums(bytesPerSum, checksumType,
+        sums, sums.position(),
+        data, data.position(), data.remaining(),
+        "", 0, false);
+  }
+
+  public static void calculateChunkedSumsByteArray(int bytesPerSum,
+      int checksumType, byte[] sums, int sumsOffset, byte[] data,
+      int dataOffset, int dataLength) {
+    nativeComputeChunkedSumsByteArray(bytesPerSum, checksumType,
+        sums, sumsOffset,
+        data, dataOffset, dataLength,
+        "", 0, false);
   }
   
-    private static native void nativeVerifyChunkedSums(
+    private static native void nativeComputeChunkedSums(
       int bytesPerSum, int checksumType,
       ByteBuffer sums, int sumsOffset,
       ByteBuffer data, int dataOffset, int dataLength,
-      String fileName, long basePos);
+      String fileName, long basePos, boolean verify);
 
-    private static native void nativeVerifyChunkedSumsByteArray(
+    private static native void nativeComputeChunkedSumsByteArray(
       int bytesPerSum, int checksumType,
       byte[] sums, int sumsOffset,
       byte[] data, int dataOffset, int dataLength,
-      String fileName, long basePos);
+      String fileName, long basePos, boolean verify);
 
   // Copy the constants over from DataChecksum so that javah will pick them up
   // and make them available in the native code header.

hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/util/NativeCrc32.c

@@ -117,12 +117,12 @@ static int convert_java_crc_type(JNIEnv *env, jint crc_type) {
   }
 }
 
-JNIEXPORT void JNICALL Java_org_apache_hadoop_util_NativeCrc32_nativeVerifyChunkedSums
+JNIEXPORT void JNICALL Java_org_apache_hadoop_util_NativeCrc32_nativeComputeChunkedSums
   (JNIEnv *env, jclass clazz,
     jint bytes_per_checksum, jint j_crc_type,
     jobject j_sums, jint sums_offset,
     jobject j_data, jint data_offset, jint data_len,
-    jstring j_filename, jlong base_pos)
+    jstring j_filename, jlong base_pos, jboolean verify)
 {
   uint8_t *sums_addr;
   uint8_t *data_addr;
@@ -166,27 +166,27 @@ JNIEXPORT void JNICALL Java_org_apache_hadoop_util_NativeCrc32_nativeVerifyChunk
   if (crc_type == -1) return; // exception already thrown
 
   // Setup complete. Actually verify checksums.
-  ret = bulk_verify_crc(data, data_len, sums, crc_type,
+  ret = bulk_crc(data, data_len, sums, crc_type,
-                            bytes_per_checksum, &error_data);
+                            bytes_per_checksum, verify ? &error_data : NULL);
-  if (likely(ret == CHECKSUMS_VALID)) {
+  if (likely(verify && ret == CHECKSUMS_VALID || !verify && ret == 0)) {
     return;
-  } else if (unlikely(ret == INVALID_CHECKSUM_DETECTED)) {
+  } else if (unlikely(verify && ret == INVALID_CHECKSUM_DETECTED)) {
     long pos = base_pos + (error_data.bad_data - data);
     throw_checksum_exception(
       env, error_data.got_crc, error_data.expected_crc,
       j_filename, pos);
   } else {
     THROW(env, "java/lang/AssertionError",
-      "Bad response code from native bulk_verify_crc");
+      "Bad response code from native bulk_crc");
   }
 }
 
-JNIEXPORT void JNICALL Java_org_apache_hadoop_util_NativeCrc32_nativeVerifyChunkedSumsByteArray
+JNIEXPORT void JNICALL Java_org_apache_hadoop_util_NativeCrc32_nativeComputeChunkedSumsByteArray
   (JNIEnv *env, jclass clazz,
     jint bytes_per_checksum, jint j_crc_type,
     jarray j_sums, jint sums_offset,
     jarray j_data, jint data_offset, jint data_len,
-    jstring j_filename, jlong base_pos)
+    jstring j_filename, jlong base_pos, jboolean verify)
 {
   uint8_t *sums_addr;
   uint8_t *data_addr;
@@ -237,21 +237,21 @@ JNIEXPORT void JNICALL Java_org_apache_hadoop_util_NativeCrc32_nativeVerifyChunk
     data = data_addr + data_offset + checksumNum * bytes_per_checksum;
 
     // Setup complete. Actually verify checksums.
-    ret = bulk_verify_crc(data, MIN(numChecksumsPerIter * bytes_per_checksum,
+    ret = bulk_crc(data, MIN(numChecksumsPerIter * bytes_per_checksum,
-                                    data_len - checksumNum * bytes_per_checksum),
+                             data_len - checksumNum * bytes_per_checksum),
-                          sums, crc_type, bytes_per_checksum, &error_data);
+                   sums, crc_type, bytes_per_checksum, verify ? &error_data : NULL);
     (*env)->ReleasePrimitiveArrayCritical(env, j_data, data_addr, 0);
     (*env)->ReleasePrimitiveArrayCritical(env, j_sums, sums_addr, 0);
-    if (unlikely(ret == INVALID_CHECKSUM_DETECTED)) {
+    if (unlikely(verify && ret == INVALID_CHECKSUM_DETECTED)) {
       long pos = base_pos + (error_data.bad_data - data) + checksumNum *
         bytes_per_checksum;
       throw_checksum_exception(
         env, error_data.got_crc, error_data.expected_crc,
         j_filename, pos);
       return;
-    } else if (unlikely(ret != CHECKSUMS_VALID)) {
+    } else if (unlikely(verify && ret != CHECKSUMS_VALID || !verify && ret != 0)) {
       THROW(env, "java/lang/AssertionError",
-        "Bad response code from native bulk_verify_crc");
+        "Bad response code from native bulk_crc");
       return;
     }
     checksumNum += numChecksumsPerIter;

hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/util/bulk_crc32.c

@@ -55,40 +55,23 @@ static void pipelined_crc32c(uint32_t *crc1, uint32_t *crc2, uint32_t *crc3, con
 static int cached_cpu_supports_crc32; // initialized by constructor below
 static uint32_t crc32c_hardware(uint32_t crc, const uint8_t* data, size_t length);
 
-int bulk_calculate_crc(const uint8_t *data, size_t data_len,
+static inline int store_or_verify(uint32_t *sums, uint32_t crc,
-                    uint32_t *sums, int checksum_type,
+                                   int is_verify) {
-                    int bytes_per_checksum) {
+  if (!is_verify) {
-  uint32_t crc;
+    *sums = crc;
-  crc_update_func_t crc_update_func;
+    return 1;
-
+  } else {
-  switch (checksum_type) {
+    return crc == *sums;
-    case CRC32_ZLIB_POLYNOMIAL:
-      crc_update_func = crc32_zlib_sb8;
-      break;
-    case CRC32C_POLYNOMIAL:
-      crc_update_func = crc32c_sb8;
-      break;
-    default:
-      return -EINVAL;
-      break;
   }
-  while (likely(data_len > 0)) {
-    int len = likely(data_len >= bytes_per_checksum) ? bytes_per_checksum : data_len;
-    crc = CRC_INITIAL_VAL;
-    crc = crc_update_func(crc, data, len);
-    *sums = ntohl(crc_val(crc));
-    data += len;
-    data_len -= len;
-    sums++;
-  }
-  return 0;
 }
 
-int bulk_verify_crc(const uint8_t *data, size_t data_len,
+int bulk_crc(const uint8_t *data, size_t data_len,
-                    const uint32_t *sums, int checksum_type,
+                    uint32_t *sums, int checksum_type,
                     int bytes_per_checksum,
                     crc32_error_t *error_info) {
 
+  int is_verify = error_info != NULL;
+
 #ifdef USE_PIPELINED
   uint32_t crc1, crc2, crc3;
   int n_blocks = data_len / bytes_per_checksum;
@@ -112,7 +95,7 @@ int bulk_verify_crc(const uint8_t *data, size_t data_len,
       }
       break;
     default:
-      return INVALID_CHECKSUM_TYPE;
+      return is_verify ? INVALID_CHECKSUM_TYPE : -EINVAL;
   }
 
 #ifdef USE_PIPELINED
@@ -122,16 +105,15 @@ int bulk_verify_crc(const uint8_t *data, size_t data_len,
       crc1 = crc2 = crc3 = CRC_INITIAL_VAL;
       pipelined_crc32c(&crc1, &crc2, &crc3, data, bytes_per_checksum, 3);
 
-      crc = ntohl(crc_val(crc1));
+      if (unlikely(!store_or_verify(sums, (crc = ntohl(crc_val(crc1))), is_verify)))
-      if ((crc = ntohl(crc_val(crc1))) != *sums)
         goto return_crc_error;
       sums++;
       data += bytes_per_checksum;
-      if ((crc = ntohl(crc_val(crc2))) != *sums)
+      if (unlikely(!store_or_verify(sums, (crc = ntohl(crc_val(crc2))), is_verify)))
         goto return_crc_error;
       sums++;
       data += bytes_per_checksum;
-      if ((crc = ntohl(crc_val(crc3))) != *sums)
+      if (unlikely(!store_or_verify(sums, (crc = ntohl(crc_val(crc3))), is_verify)))
         goto return_crc_error;
       sums++;
       data += bytes_per_checksum;
@@ -143,12 +125,12 @@ int bulk_verify_crc(const uint8_t *data, size_t data_len,
       crc1 = crc2 = crc3 = CRC_INITIAL_VAL;
       pipelined_crc32c(&crc1, &crc2, &crc3, data, bytes_per_checksum, n_blocks);
 
-      if ((crc = ntohl(crc_val(crc1))) != *sums)
+      if (unlikely(!store_or_verify(sums, (crc = ntohl(crc_val(crc1))), is_verify)))
         goto return_crc_error;
       data += bytes_per_checksum;
       sums++;
       if (n_blocks == 2) {
-        if ((crc = ntohl(crc_val(crc2))) != *sums)
+        if (unlikely(!store_or_verify(sums, (crc = ntohl(crc_val(crc2))), is_verify)))
           goto return_crc_error;
         sums++;
         data += bytes_per_checksum;
@@ -160,10 +142,10 @@ int bulk_verify_crc(const uint8_t *data, size_t data_len,
       crc1 = crc2 = crc3 = CRC_INITIAL_VAL;
       pipelined_crc32c(&crc1, &crc2, &crc3, data, remainder, 1);
 
-      if ((crc = ntohl(crc_val(crc1))) != *sums)
+      if (unlikely(!store_or_verify(sums, (crc = ntohl(crc_val(crc1))), is_verify)))
         goto return_crc_error;
     }
-    return CHECKSUMS_VALID;
+    return is_verify ? CHECKSUMS_VALID : 0;
   }
 #endif
 
@@ -172,14 +154,14 @@ int bulk_verify_crc(const uint8_t *data, size_t data_len,
     crc = CRC_INITIAL_VAL;
     crc = crc_update_func(crc, data, len);
     crc = ntohl(crc_val(crc));
-    if (unlikely(crc != *sums)) {
+    if (unlikely(!store_or_verify(sums, crc, is_verify))) {
       goto return_crc_error;
     }
     data += len;
     data_len -= len;
     sums++;
   }
-  return CHECKSUMS_VALID;
+  return is_verify ? CHECKSUMS_VALID : 0;
 
 return_crc_error:
   if (error_info != NULL) {

hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/util/bulk_crc32.h

@@ -42,49 +42,32 @@ typedef struct crc32_error {
 
 
 /**
- * Verify a buffer of data which is checksummed in chunks
+ * Either calculates checksums for or verifies a buffer of data.
- * of bytes_per_checksum bytes. The checksums are each 32 bits
+ * Checksums performed in chunks of bytes_per_checksum bytes. The checksums
- * and are stored in sequential indexes of the 'sums' array.
+ * are each 32 bits and are stored in sequential indexes of the 'sums' array.
+ * Verification is done (sums is assumed to already contain the checksums)
+ * if error_info is non-null; otherwise calculation is done and checksums
+ * are stored into sums.
  *
  * @param data                  The data to checksum
  * @param dataLen               Length of the data buffer
- * @param sums                  (out param) buffer to write checksums into.
+ * @param sums                  (out param) buffer to write checksums into or
- *                              It must contain at least dataLen * 4 bytes.
+ *                              where checksums are already stored.
+ *                              It must contain at least
+ *                              ((dataLen - 1) / bytes_per_checksum + 1) * 4 bytes.
  * @param checksum_type         One of the CRC32 algorithm constants defined 
  *                              above
  * @param bytes_per_checksum    How many bytes of data to process per checksum.
- * @param error_info            If non-NULL, will be filled in if an error
+ * @param error_info            If non-NULL, verification will be performed and
- *                              is detected
+ *                              it will be filled in if an error
+ *                              is detected. Otherwise calculation is performed.
  *
  * @return                      0 for success, non-zero for an error, result codes
- *                              for which are defined above
+ *                              for verification are defined above
  */
-extern int bulk_verify_crc(const uint8_t *data, size_t data_len,
+extern int bulk_crc(const uint8_t *data, size_t data_len,
-    const uint32_t *sums, int checksum_type,
+    uint32_t *sums, int checksum_type,
     int bytes_per_checksum,
     crc32_error_t *error_info);
 
-/**
- * Calculate checksums for some data.
- *
- * The checksums are each 32 bits and are stored in sequential indexes of the
- * 'sums' array.
- *
- * This function is not (yet) optimized.  It is provided for testing purposes
- * only.
- *
- * @param data                  The data to checksum
- * @param dataLen               Length of the data buffer
- * @param sums                  (out param) buffer to write checksums into.
- *                              It must contain at least dataLen * 4 bytes.
- * @param checksum_type         One of the CRC32 algorithm constants defined 
- *                              above
- * @param bytesPerChecksum      How many bytes of data to process per checksum.
- *
- * @return                      0 for success, non-zero for an error
- */
-int bulk_calculate_crc(const uint8_t *data, size_t data_len,
-                    uint32_t *sums, int checksum_type,
-                    int bytes_per_checksum);
-
 #endif

hadoop-common-project/hadoop-common/src/main/native/src/test/org/apache/hadoop/util/test_bulk_crc32.c

@@ -48,9 +48,9 @@ static int testBulkVerifyCrc(int dataLen, int crcType, int bytesPerChecksum)
   sums = calloc(sizeof(uint32_t),
                 (dataLen + bytesPerChecksum - 1) / bytesPerChecksum);
 
-  EXPECT_ZERO(bulk_calculate_crc(data, dataLen, sums, crcType,
+  EXPECT_ZERO(bulk_crc(data, dataLen, sums, crcType,
-                                 bytesPerChecksum));
+                                 bytesPerChecksum, NULL));
-  EXPECT_ZERO(bulk_verify_crc(data, dataLen, sums, crcType,
+  EXPECT_ZERO(bulk_crc(data, dataLen, sums, crcType,
                             bytesPerChecksum, &errorData));
   free(data);
   free(sums);

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestDataChecksum.java

@@ -19,6 +19,9 @@ package org.apache.hadoop.util;
 
 import java.nio.ByteBuffer;
 import java.util.Random;
+import java.util.concurrent.TimeUnit;
+
+import com.google.common.base.Stopwatch;
 
 import org.apache.hadoop.fs.ChecksumException;
 import org.junit.Test;
@@ -53,68 +56,113 @@ public class TestDataChecksum {
       }
     }
   }
-  
+
-  private void doBulkTest(DataChecksum checksum, int dataLength,
+  private static class Harness {
-      boolean useDirect) throws Exception {
+    final DataChecksum checksum;
-    System.err.println("Testing bulk checksums of length " + 
+    final int dataLength, sumsLength, numSums;
-        dataLength + " with " +
+    ByteBuffer dataBuf, checksumBuf;
-        (useDirect ? "direct" : "array-backed") + " buffers");
+
-    int numSums = (dataLength - 1)/checksum.getBytesPerChecksum() + 1;
+    Harness(DataChecksum checksum, int dataLength, boolean useDirect) {
-    int sumsLength = numSums * checksum.getChecksumSize();
+      this.checksum = checksum;
-    
+      this.dataLength = dataLength;
-    byte data[] = new byte[dataLength +
+
-                           DATA_OFFSET_IN_BUFFER +
+      numSums = (dataLength - 1)/checksum.getBytesPerChecksum() + 1;
-                           DATA_TRAILER_IN_BUFFER];
+      sumsLength = numSums * checksum.getChecksumSize();
-    new Random().nextBytes(data);
+
-    ByteBuffer dataBuf = ByteBuffer.wrap(
+      byte data[] = new byte[dataLength +
+                             DATA_OFFSET_IN_BUFFER +
+                             DATA_TRAILER_IN_BUFFER];
+      new Random().nextBytes(data);
+      dataBuf = ByteBuffer.wrap(
         data, DATA_OFFSET_IN_BUFFER, dataLength);
 
-    byte checksums[] = new byte[SUMS_OFFSET_IN_BUFFER + sumsLength];
+      byte checksums[] = new byte[SUMS_OFFSET_IN_BUFFER + sumsLength];
-    ByteBuffer checksumBuf = ByteBuffer.wrap(
+      checksumBuf = ByteBuffer.wrap(
         checksums, SUMS_OFFSET_IN_BUFFER, sumsLength);
-    
-    // Swap out for direct buffers if requested.
-    if (useDirect) {
-      dataBuf = directify(dataBuf);
-      checksumBuf = directify(checksumBuf);
-    }
-    
-    // calculate real checksum, make sure it passes
-    checksum.calculateChunkedSums(dataBuf, checksumBuf);
-    checksum.verifyChunkedSums(dataBuf, checksumBuf, "fake file", 0);
 
-    // Change a byte in the header and in the trailer, make sure
+      // Swap out for direct buffers if requested.
-    // it doesn't affect checksum result
+      if (useDirect) {
-    corruptBufferOffset(checksumBuf, 0);
+        dataBuf = directify(dataBuf);
-    checksum.verifyChunkedSums(dataBuf, checksumBuf, "fake file", 0);
+        checksumBuf = directify(checksumBuf);
-    corruptBufferOffset(dataBuf, 0);
+      }
-    dataBuf.limit(dataBuf.limit() + 1);
-    corruptBufferOffset(dataBuf, dataLength + DATA_OFFSET_IN_BUFFER);
-    dataBuf.limit(dataBuf.limit() - 1);
-    checksum.verifyChunkedSums(dataBuf, checksumBuf, "fake file", 0);    
-    
-    // Make sure bad checksums fail - error at beginning of array
-    corruptBufferOffset(checksumBuf, SUMS_OFFSET_IN_BUFFER);
-    try {
-      checksum.verifyChunkedSums(dataBuf, checksumBuf, "fake file", 0);
-      fail("Did not throw on bad checksums");
-    } catch (ChecksumException ce) {
-      assertEquals(0, ce.getPos());
     }
 
-    // Make sure bad checksums fail - error at end of array
+    void testCorrectness() throws ChecksumException {
-    uncorruptBufferOffset(checksumBuf, SUMS_OFFSET_IN_BUFFER);
+      // calculate real checksum, make sure it passes
-    corruptBufferOffset(checksumBuf, SUMS_OFFSET_IN_BUFFER + sumsLength - 1);
+      checksum.calculateChunkedSums(dataBuf, checksumBuf);
-    try {
       checksum.verifyChunkedSums(dataBuf, checksumBuf, "fake file", 0);
-      fail("Did not throw on bad checksums");
+
-    } catch (ChecksumException ce) {
+      // Change a byte in the header and in the trailer, make sure
-      int expectedPos = checksum.getBytesPerChecksum() * (numSums - 1);
+      // it doesn't affect checksum result
-      assertEquals(expectedPos, ce.getPos());
+      corruptBufferOffset(checksumBuf, 0);
-      assertTrue(ce.getMessage().contains("fake file"));
+      checksum.verifyChunkedSums(dataBuf, checksumBuf, "fake file", 0);
+      corruptBufferOffset(dataBuf, 0);
+      dataBuf.limit(dataBuf.limit() + 1);
+      corruptBufferOffset(dataBuf, dataLength + DATA_OFFSET_IN_BUFFER);
+      dataBuf.limit(dataBuf.limit() - 1);
+      checksum.verifyChunkedSums(dataBuf, checksumBuf, "fake file", 0);
+
+      // Make sure bad checksums fail - error at beginning of array
+      corruptBufferOffset(checksumBuf, SUMS_OFFSET_IN_BUFFER);
+      try {
+        checksum.verifyChunkedSums(dataBuf, checksumBuf, "fake file", 0);
+        fail("Did not throw on bad checksums");
+      } catch (ChecksumException ce) {
+        assertEquals(0, ce.getPos());
+      }
+
+      // Make sure bad checksums fail - error at end of array
+      uncorruptBufferOffset(checksumBuf, SUMS_OFFSET_IN_BUFFER);
+      corruptBufferOffset(checksumBuf, SUMS_OFFSET_IN_BUFFER + sumsLength - 1);
+      try {
+        checksum.verifyChunkedSums(dataBuf, checksumBuf, "fake file", 0);
+        fail("Did not throw on bad checksums");
+      } catch (ChecksumException ce) {
+        int expectedPos = checksum.getBytesPerChecksum() * (numSums - 1);
+        assertEquals(expectedPos, ce.getPos());
+        assertTrue(ce.getMessage().contains("fake file"));
+      }
     }
   }
-  
+
+  private void doBulkTest(DataChecksum checksum, int dataLength,
+      boolean useDirect) throws Exception {
+    System.err.println("Testing bulk checksums of length " +
+        dataLength + " with " +
+        (useDirect ? "direct" : "array-backed") + " buffers");
+
+    new Harness(checksum, dataLength, useDirect).testCorrectness();
+  }
+
+  /**
+   * Simple performance test for the "common case" checksum usage in HDFS:
+   * computing and verifying CRC32C with 512 byte chunking on native
+   * buffers.
+   */
+  @Test
+  public void commonUsagePerfTest() throws Exception {
+    final int NUM_RUNS = 5;
+    final DataChecksum checksum = DataChecksum.newDataChecksum(DataChecksum.Type.CRC32C, 512);
+    final int dataLength = 512 * 1024 * 1024;
+    Harness h = new Harness(checksum, dataLength, true);
+
+    for (int i = 0; i < NUM_RUNS; i++) {
+      Stopwatch s = new Stopwatch().start();
+      // calculate real checksum, make sure it passes
+      checksum.calculateChunkedSums(h.dataBuf, h.checksumBuf);
+      s.stop();
+      System.err.println("Calculate run #" + i + ": " +
+                         s.elapsedTime(TimeUnit.MICROSECONDS) + "us");
+
+      s = new Stopwatch().start();
+      // calculate real checksum, make sure it passes
+      checksum.verifyChunkedSums(h.dataBuf, h.checksumBuf, "fake file", 0);
+      s.stop();
+      System.err.println("Verify run #" + i + ": " +
+                         s.elapsedTime(TimeUnit.MICROSECONDS) + "us");
+    }
+  }
+
   @Test
   public void testEquality() {
     assertEquals(