SnappyOutputStream.close() is not idempotent

[JoshRosen]

SnappyOutputStream's close() method is not idempotent, which can lead to stream corruption issues when CachedBufferAllocator is used (the default behavior).

Here's the current source for close():

    public void close() throws IOException {
        try {
            flush();
            out.close();
        } finally {
            inputBufferAllocator.release(inputBuffer);
            outputBufferAllocator.release(outputBuffer);
        }
    }

If we call close() twice, then we'll free the buffers twice. After the first close() call, the stream's buffers will be released back to the BachedBufferAllocator's buffer pool for re-use. If we create a new SnappyOutputStream, this stream will re-use the buffers from the BachedBufferAllocator. If we now call close() on the original stream a second time, we'll end up placing the same buffers into the BachedBufferAllocator's buffer pool even though another non-closed SnappyOutputStream is now using them. This can lead to scenarios where two open SnappyOutputStreams share the same buffers, leading to stream corruption issues.

This should be pretty easy to fix; I'm working on a unit test + patch now.

[xerial]

Good catch!

[xerial]

Uploaded 1.1.2-RC2-SNAPSHOT