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From phrocker <...@git.apache.org>
Subject [GitHub] accumulo pull request #134: ACCUMULO-4391 Added synchronization around the a...
Date Wed, 27 Jul 2016 23:32:08 GMT
Github user phrocker commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/134#discussion_r72543018
  
    --- Diff: core/src/main/java/org/apache/accumulo/core/file/rfile/bcfile/BoundedRangeFileInputStream.java
---
    @@ -62,12 +62,15 @@ public BoundedRangeFileInputStream(FSDataInputStream in, long offset,
long lengt
     
       @Override
       public int available() throws IOException {
    -    int avail = in.available();
    -    if (pos + avail > end) {
    -      avail = (int) (end - pos);
    -    }
    +    final FSDataInputStream inLocal = in;
    +    synchronized (inLocal) {
    +      int avail = in.available();
    --- End diff --
    
    We don't follow the paradigm prescribed by the interface. If used in a parallel environment
the block region may all be different. The underlying stream itself will likely be nowhere
near your sought position and therefore availability means nothing to the instance that is
being called; however, if we used the length provided by the Constructor at least we have
some semblance of what availability means for a bounded range input stream. Anyone making
a decision based on availability could have a completely incorrect meaning because seek always
occurs within a read. This will be further compounded due to threading. 


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