[GitHub] brooklyn-server issue #491: (WIP) execAsync parameter for SshMachineLocation...

[aledsage <gi...@git.apache.org>]

Github user aledsage commented on the issue:

    https://github.com/apache/brooklyn-server/pull/491
  
    I started looking into why `testSshExecScript()` was failing. First quick comment: you need to enable the feature:
    ```
        @BeforeMethod(alwaysRun=true)
        public void setUp() throws Exception {
            origAsyncExecEnablement = BrooklynFeatureEnablement.setEnablement(BrooklynFeatureEnablement.FEATURE_SSH_ASYNC_EXEC, true);
            super.setUp();
        }
    
        @AfterMethod(alwaysRun=true)
        public void tearDown() throws Exception {
            try {
                super.tearDown();
            } finally {
                if (origAsyncExecEnablement != null) {
                    BrooklynFeatureEnablement.setEnablement(BrooklynFeatureEnablement.FEATURE_SSH_ASYNC_EXEC, origAsyncExecEnablement);
                    origAsyncExecEnablement = null;
                }
                RecordingSshjTool.clear();
            }
        }
    ```
    
    But it still fails. It doesn't manage to get the stdout/stderr from the long polling. If you change the test to also pass in `SshMachineLocation.NO_STDOUT_LOGGING.getName(), true` then it works.
    
    The problems seems to be the interaction between the `PipedOutputStream` (added in `ExecWithLoggingHelpers.execWithLogging()`) and the `CountingOutputStream` (added in `SshjTool.execScriptAsyncAndPoll`'s `longPoll()`).
    
    I don't have time to investigate further just now, unfortunately. I suggest we park this for a bit longer.
    
    I'm not sure why we're wrapping it in a `PipedOutputStream` (which allows us to also receive the bytes and log them, using the `StreamGobbler` to respond to callbacks about the bytes being received). I'm not sure why we don't just wrap the `OutputStream` in a much simpler way, in a similar way to how guava wraps `CountingOutputStream` - where on each byte that is written it can check if that's the end of a line and log it accordingly.
    
    But we don't want to be making changing like that just now, and certainly not as part of this PR.


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