[Twisted-Python] [patch] 1/4 process disconneting

[Andrea Arcangeli]

Here a list of fixes present in CPUShare-Twisted mercurial tree and
missing in Twisted SVN trunk. Most of these have been posted as a ticket
in trac without feedback (by now the links in the tickets are obsolete
due to bugs in tailor that required a rebuild of the SVN->HG repository,
but nobody asked about the dangling link anyway). So I rensend them here
just in case somebody is interested. I will not answer to replies
because I've no time, sorry. Each email contains one patch.

This fixes a reentrance problem in connectionLost if invoked by shutdown
at the same time as the real disconnect.

diff -r 493b5c24e0f3 twisted/internet/process.py
--- a/twisted/internet/process.py	Tue May 16 04:57:00 2006 +0000
+++ b/twisted/internet/process.py	Wed May 17 15:59:28 2006 +0200
@@ -82,7 +82,24 @@ def detectLinuxBrokenPipeBehavior():
 # Call at import time
 detectLinuxBrokenPipeBehavior()
 
-class ProcessWriter(abstract.FileDescriptor):
+class ProcessReaderWriter(abstract.FileDescriptor):
+    """(Internal) Helper class to avoid code duplication between
+    ProcessReader and ProcessWriter."""
+    def connectionLost(self, reason):
+        """Close my end of the pipe, signal the Process (which signals the
+        ProcessProtocol).
+        See also abstract.FileDescriptor.connectionLost.
+        """
+        # connectionLost can be called multiple times, for example
+        # both from the loseConnection timer, and from the
+        # shutdown event as well, but childConnectionLost
+        # needs to be invoked only once
+        disconnected = self.disconnected
+        abstract.FileDescriptor.connectionLost(self, reason)
+        if not disconnected:
+            self.proc.childConnectionLost(self.name, reason)
+
+class ProcessWriter(ProcessReaderWriter):
     """(Internal) Helper class to write into a Process's input pipe.
 
     I am a helper which describes a selectable asynchronous writer to a
@@ -174,14 +191,8 @@ class ProcessWriter(abstract.FileDescrip
         else:
             self.stopReading()
         
-    def connectionLost(self, reason):
-        """See abstract.FileDescriptor.connectionLost.
-        """
-        abstract.FileDescriptor.connectionLost(self, reason)
-        self.proc.childConnectionLost(self.name, reason)
-
-
-class ProcessReader(abstract.FileDescriptor):
+
+class ProcessReader(ProcessReaderWriter):
     """ProcessReader
 
     I am a selectable representation of a process's output pipe, such as
@@ -224,13 +235,6 @@ class ProcessReader(abstract.FileDescrip
             self.disconnecting = 1
             self.stopReading()
             self.reactor.callLater(0, self.connectionLost, failure.Failure(CONNECTION_DONE))
-    
-    def connectionLost(self, reason):
-        """Close my end of the pipe, signal the Process (which signals the
-        ProcessProtocol).
-        """
-        abstract.FileDescriptor.connectionLost(self, reason)
-        self.proc.childConnectionLost(self.name, reason)
 
 
 class Process(styles.Ephemeral):