[tor-commits] [vidalia/alpha] Make sure there is a ReceiveWaiter in the queue before sending any control commands

[chiiph at torproject.org]

commit 594bacda9e5550c3bf4032328babccc959c54cdb
Author: Tomás Touceda <chiiph at torproject.org>
Date:   Fri May 25 18:45:55 2012 -0300

    Make sure there is a ReceiveWaiter in the queue before sending any control commands
---
 changes/raceCondition                |    3 +++
 src/torcontrol/ControlConnection.cpp |   13 ++++++++-----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/changes/raceCondition b/changes/raceCondition
new file mode 100644
index 0000000..82e4b3c
--- /dev/null
+++ b/changes/raceCondition
@@ -0,0 +1,3 @@
+  Internal cleanups and improvements:
+  o Make sure there is a ReceiveWaiter in the queue before issuing a
+    ControlCommand to avoid deadlocks in the event loop.
\ No newline at end of file
diff --git a/src/torcontrol/ControlConnection.cpp b/src/torcontrol/ControlConnection.cpp
index 389a6e3..6497147 100644
--- a/src/torcontrol/ControlConnection.cpp
+++ b/src/torcontrol/ControlConnection.cpp
@@ -251,21 +251,24 @@ ControlConnection::send(const ControlCommand &cmd,
   bool result = false;
   QString errstr;
 
-  if (send(cmd, &errstr)) {
-    /* Create and enqueue a new receive waiter */
-    ReceiveWaiter *w = new ReceiveWaiter();
-    _recvQueue.enqueue(w);
+  /* Preentively create and enqueue a new receive waiter */
+  ReceiveWaiter *w = new ReceiveWaiter();
+  _recvQueue.enqueue(w);
 
+  if (send(cmd, &errstr)) {
     /* Wait for and get the result, clean up, and return */
     result = w->getResult(&reply, &errstr);
+
     if (!result)
       tc::error("Failed to receive control reply: %1").arg(errstr);
-    delete w;
   } else {
     tc::error("Failed to send control command (%1): %2").arg(cmd.keyword())
                                                         .arg(errstr);
+    _recvQueue.dequeue();
   }
 
+  delete w;
+
   if (!result && errmsg)
     *errmsg = errstr;
   return result;