serialize exceptions across mp

copyparty/broker_mp.py

@@ -7,6 +7,7 @@ import threading
 from .__init__ import PY2, WINDOWS
 from .broker_mpw import MpWorker
 from .util import mp
+from .broker_util import *
 
 
 if PY2 and not WINDOWS:
@@ -109,7 +110,7 @@ class BrokerMp(object):
                     obj = getattr(obj, node)
 
                 # TODO will deadlock if dest performs another ipc
-                rv = obj(*args)
+                rv = try_exec(obj, *args, want_retval=retq_id)
 
                 if retq_id:
                     proc.q_pend.put([retq_id, "retq", rv])

copyparty/broker_mpw.py

@@ -8,7 +8,7 @@ import threading
 
 from .__init__ import PY2, WINDOWS
 from .httpsrv import HttpSrv
-from .util import Queue
+from .broker_util import *
 
 if PY2 and not WINDOWS:
     import pickle  # nosec
@@ -93,7 +93,7 @@ class MpWorker(object):
 
     def put(self, want_retval, dest, *args):
         if want_retval:
-            retq = Queue(1)
+            retq = ExceptionalQueue(1)
             retq_id = id(retq)
             with self.retpend_mutex:
                 self.retpend[retq_id] = retq

copyparty/broker_thr.py

@@ -4,8 +4,8 @@ from __future__ import print_function, unicode_literals
 
 import threading
 
-from .util import Queue
 from .httpsrv import HttpSrv
+from .broker_util import *
 
 
 class BrokerThr(object):
@@ -39,13 +39,12 @@ class BrokerThr(object):
                 obj = getattr(obj, node)
 
             # TODO will deadlock if dest performs another ipc
-            rv = obj(*args)
-
+            rv = try_exec(obj, *args, want_retval=want_retval)
             if not want_retval:
                 return
 
             # pretend we're broker_mp
-            retq = Queue(1)
+            retq = ExceptionalQueue(1)
             retq.put(rv)
             return retq
 

copyparty/broker_util.py

@@ -0,0 +1,45 @@
+# coding: utf-8
+from __future__ import print_function, unicode_literals
+
+
+import traceback
+
+from .__init__ import PY2
+from .util import Pebkac
+
+if not PY2:
+    from queue import Queue
+else:
+    from Queue import Queue  # pylint: disable=import-error,no-name-in-module
+
+
+class ExceptionalQueue(Queue):
+    def get(self, block=True, timeout=None):
+        rv = super(ExceptionalQueue, self).get(block, timeout)
+
+        # TODO: how expensive is this?
+        if isinstance(rv, list):
+            if rv[0] == "exception":
+                if rv[1] == "pebkac":
+                    raise Pebkac(*rv[2:])
+                else:
+                    raise Exception(rv[2])
+
+        return rv
+
+
+def try_exec(func, *args, want_retval=False):
+    try:
+        return func(*args)
+
+    except Pebkac as ex:
+        if not want_retval:
+            raise
+
+        return ["exception", "pebkac", ex.code, str(ex)]
+
+    except:
+        if not want_retval:
+            raise
+
+        return ["exception", "stack", traceback.format_exc()]