[incubator-uniffle] branch branch-0.5.0 updated: [Bug] Fix skip() api maybe skip unexpected bytes which makes inconsistent data (#40) (#52)

[roryqi]

This is an automated email from the ASF dual-hosted git repository.

roryqi pushed a commit to branch branch-0.5.0
in repository https://gitbox.apache.org/repos/asf/incubator-uniffle.git


The following commit(s) were added to refs/heads/branch-0.5.0 by this push:
     new 1554f9f  [Bug] Fix skip() api maybe skip unexpected bytes which makes 
inconsistent data (#40) (#52)
1554f9f is described below

commit 1554f9f5f6a6e117174794526b3a20699078efae
Author: Colin <coli...@tencent.com>
AuthorDate: Tue Jul 12 16:32:15 2022 +0800

    [Bug] Fix skip() api maybe skip unexpected bytes which makes inconsistent 
data (#40) (#52)
    
    ### What changes were proposed in this pull request?
    Fix bug when call `inputstream.skip()` which may return unexpected result
    
    
    ### Why are the changes needed?
    Get exception messages as following, and it maybe caused by unexpected data 
from `Local` storage
    ```
    com.tencent.rss.common.exception.RssException: Unexpected crc value for 
blockId[9992363390829154], expected:2562548848, actual:2244862586
            at 
com.tencent.rss.client.impl.ShuffleReadClientImpl.readShuffleBlockData(ShuffleReadClientImpl.java:184)
            at 
org.apache.spark.shuffle.reader.RssShuffleDataIterator.hasNext(RssShuffleDataIterator.java:99)
            at 
org.apache.spark.InterruptibleIterator.hasNext(InterruptibleIterator.scala:39)
            at scala.collection.Iterator$$anon$11.hasNext(Iterator.scala:408)
    ```
    
    
    ### Does this PR introduce _any_ user-facing change?
    No
    
    
    ### How was this patch tested?
    With current UTs
---
 .../rss/storage/handler/impl/LocalFileReader.java       | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git 
a/storage/src/main/java/com/tencent/rss/storage/handler/impl/LocalFileReader.java
 
b/storage/src/main/java/com/tencent/rss/storage/handler/impl/LocalFileReader.java
index 8ff2f5f..f16846a 100644
--- 
a/storage/src/main/java/com/tencent/rss/storage/handler/impl/LocalFileReader.java
+++ 
b/storage/src/main/java/com/tencent/rss/storage/handler/impl/LocalFileReader.java
@@ -42,7 +42,22 @@ public class LocalFileReader implements FileReader, 
Closeable {
 
   public byte[] read(long offset, int length) {
     try {
-      dataInputStream.skip(offset);
+      long targetSkip = offset;
+      // comments from skip API:
+      // The skip method may, for a variety of reasons,
+      // end up skipping over some smaller number of bytes, possibly 0
+      // the result should be checked and try again until skip expectation 
length
+      while (targetSkip > 0) {
+        long realSkip = dataInputStream.skip(targetSkip);
+        if (realSkip == -1) {
+          throw new RuntimeException("Unexpected EOF when skip bytes");
+        }
+        targetSkip -= realSkip;
+        if (targetSkip > 0) {
+          LOG.warn("Got unexpected skip for path:" + path + " with offset["
+              + offset + "], length[" + length + "], remain[" + targetSkip + 
"]");
+        }
+      }
       byte[] buf = new byte[length];
       dataInputStream.readFully(buf);
       return buf;