Added check for signals in poll()

Also removed the unused pluck() function

src/python/grpcio/grpc/_cython/_cygrpc/completion_queue.pxd.pxi

@@ -31,9 +31,6 @@
 cdef class CompletionQueue:
 
   cdef grpc_completion_queue *c_completion_queue
-  cdef object pluck_condition
-  cdef int num_plucking
-  cdef int num_polling
   cdef bint is_shutting_down
   cdef bint is_shutdown
 

src/python/grpcio/grpc/_cython/_cygrpc/completion_queue.pyx.pxi

@@ -32,6 +32,8 @@ cimport cpython
 import threading
 import time
 
+cdef int _INTERRUPT_CHECK_PERIOD_MS = 200
+
 
 cdef class CompletionQueue:
 
@@ -40,9 +42,6 @@ cdef class CompletionQueue:
       self.c_completion_queue = grpc_completion_queue_create(NULL)
     self.is_shutting_down = False
     self.is_shutdown = False
-    self.pluck_condition = threading.Condition()
-    self.num_plucking = 0
-    self.num_polling = 0
 
   cdef _interpret_event(self, grpc_event event):
     cdef OperationTag tag = None
@@ -83,45 +82,27 @@ cdef class CompletionQueue:
   def poll(self, Timespec deadline=None):
     # We name this 'poll' to avoid problems with CPython's expectations for
     # 'special' methods (like next and __next__).
+    cdef gpr_timespec c_increment
+    cdef gpr_timespec c_timeout
     cdef gpr_timespec c_deadline
     with nogil:
+      c_increment = gpr_time_from_millis(_INTERRUPT_CHECK_PERIOD_MS, GPR_TIMESPAN)
       c_deadline = gpr_inf_future(GPR_CLOCK_REALTIME)
-    if deadline is not None:
-      c_deadline = deadline.c_time
-    cdef grpc_event event
-
-    # Poll within a critical section to detect contention
-    with self.pluck_condition:
-      assert self.num_plucking == 0, 'cannot simultaneously pluck and poll'
-      self.num_polling += 1
-    with nogil:
-      event = grpc_completion_queue_next(
-          self.c_completion_queue, c_deadline, NULL)
-    with self.pluck_condition:
-      self.num_polling -= 1
-    return self._interpret_event(event)
-
-  def pluck(self, OperationTag tag, Timespec deadline=None):
-    # Plucking a 'None' tag is equivalent to passing control to GRPC core until
-    # the deadline.
-    cdef gpr_timespec c_deadline = gpr_inf_future(
-        GPR_CLOCK_REALTIME)
-    if deadline is not None:
-      c_deadline = deadline.c_time
-    cdef grpc_event event
-
-    # Pluck within a critical section to detect contention
-    with self.pluck_condition:
-      assert self.num_polling == 0, 'cannot simultaneously pluck and poll'
-      assert self.num_plucking < GRPC_MAX_COMPLETION_QUEUE_PLUCKERS, (
-          'cannot pluck more than {} times simultaneously'.format(
-              GRPC_MAX_COMPLETION_QUEUE_PLUCKERS))
-      self.num_plucking += 1
-    with nogil:
-      event = grpc_completion_queue_pluck(
-          self.c_completion_queue, <cpython.PyObject *>tag, c_deadline, NULL)
-    with self.pluck_condition:
-      self.num_plucking -= 1
+      if deadline is not None:
+        c_deadline = deadline.c_time
+      
+      while True:
+        c_timeout = gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), c_increment)
+        if gpr_time_cmp(c_timeout, c_deadline) > 0:
+          c_timeout = c_deadline
+        event = grpc_completion_queue_next(
+          self.c_completion_queue, c_timeout, NULL)
+        if event.type != GRPC_QUEUE_TIMEOUT or gpr_time_cmp(c_timeout, c_deadline) == 0:
+          break;
+        
+        # Handle any signals
+        with gil:
+          cpython.PyErr_CheckSignals()
     return self._interpret_event(event)
 
   def shutdown(self):

src/python/grpcio/grpc/_cython/_cygrpc/grpc.pxi

@@ -80,6 +80,12 @@ cdef extern from "grpc/_cython/loader.h":
   gpr_timespec gpr_convert_clock_type(gpr_timespec t,
                                       gpr_clock_type target_clock) nogil
 
+  gpr_timespec gpr_time_from_millis(int64_t ms, gpr_clock_type type) nogil
+
+  gpr_timespec gpr_time_add(gpr_timespec a, gpr_timespec b) nogil
+
+  int gpr_time_cmp(gpr_timespec a, gpr_timespec b) nogil
+  
   ctypedef enum grpc_status_code:
     GRPC_STATUS_OK
     GRPC_STATUS_CANCELLED

src/python/grpcio/grpc/_cython/_cygrpc/server.pyx.pxi

@@ -99,7 +99,7 @@ cdef class Server:
     with nogil:
       grpc_server_start(self.c_server)
     # Ensure the core has gotten a chance to do the start-up work
-    self.backup_shutdown_queue.pluck(None, Timespec(None))
+    self.backup_shutdown_queue.poll(Timespec(None))
 
   def add_http2_port(self, address,
                      ServerCredentials server_credentials=None):