[GitHub] [hadoop] xiaoyuyao commented on a change in pull request #830: HDDS-1530. Freon support big files larger than 2GB and add --bufferSize and --validateWrites options.

[GitBox <gi...@apache.org>]

xiaoyuyao commented on a change in pull request #830: HDDS-1530. Freon support big files larger than 2GB and add --bufferSize and --validateWrites options.
URL: https://github.com/apache/hadoop/pull/830#discussion_r285312730
 
 

 ##########
 File path: hadoop-ozone/tools/src/main/java/org/apache/hadoop/ozone/freon/RandomKeyGenerator.java
 ##########
 @@ -228,8 +243,20 @@ public Void call() throws Exception {
       init(freon.createOzoneConfiguration());
     }
 
-    keyValue =
-        DFSUtil.string2Bytes(RandomStringUtils.randomAscii(keySize - 36));
+    keyValueBuffer = DFSUtil.string2Bytes(
+        RandomStringUtils.randomAscii(bufferSize));
+
+    // Compute the common initial digest for all keys without their UUID
+    if (validateWrites) {
+      commonInitialMD = DigestUtils.getDigest(DIGEST_ALGORITHM);
+      int uuidLength = UUID.randomUUID().toString().length();
+      keySize = Math.max(uuidLength, keySize);
+      for (long nrRemaining = keySize - uuidLength; nrRemaining > 0;
+          nrRemaining -= bufferSize) {
+        int curSize = (int)Math.min(bufferSize, nrRemaining);
+        commonInitialMD.update(keyValueBuffer, 0, curSize);
 
 Review comment:
   The keyValueBuffer is only generated randomly once before the loop. Repeatedly calculate the same content won't change the digest here. Some of the commonInitalMD.update() cycles can be saved here. 

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