diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/Utility/ConcurrentOutput.hs | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/src/Utility/ConcurrentOutput.hs b/src/Utility/ConcurrentOutput.hs index 186f881f..3624ffbf 100644 --- a/src/Utility/ConcurrentOutput.hs +++ b/src/Utility/ConcurrentOutput.hs @@ -117,12 +117,17 @@ updateOutputLocker l = do -- multiple processes that are running concurrently from writing -- to stdout/stderr at the same time. -- --- The first process is allowed to write to stdout and stderr in the usual way. +-- If the process does not output to stdout or stderr, it's run +-- by createProcess entirely as usual. Only processes that can generate +-- output are handled specially: -- --- However, if another process is run concurrently with the --- first, any stdout or stderr that would have been displayed by it is --- instead buffered. The buffered output will be displayed the next time it --- is safe to do so (ie, after the first process exits). +-- A process is allowed to write to stdout and stderr in the usual +-- way, assuming it can successfully take the output lock. +-- +-- When the output lock is held (by another process or other caller of +-- `lockOutput`), the process is instead run with its stdout and stderr +-- redirected to a buffer. The buffered output will be displayed as soon +-- as the output lock becomes free. createProcessConcurrent :: P.CreateProcess -> IO (Maybe Handle, Maybe Handle, Maybe Handle, P.ProcessHandle) createProcessConcurrent p | hasoutput (P.std_out p) || hasoutput (P.std_err p) = |