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"""Test making many calls and immediately cancelling most of them."""

import threading
import unittest

from grpc._cython import cygrpc
from grpc.framework.foundation import logging_pool
from tests.unit.framework.common import test_constants

_INFINITE_FUTURE = cygrpc.Timespec(float('+inf'))
_EMPTY_FLAGS = 0
_EMPTY_METADATA = cygrpc.Metadata(())

_SERVER_SHUTDOWN_TAG = 'server_shutdown'
_REQUEST_CALL_TAG = 'request_call'
_RECEIVE_CLOSE_ON_SERVER_TAG = 'receive_close_on_server'
_RECEIVE_MESSAGE_TAG = 'receive_message'
_SERVER_COMPLETE_CALL_TAG = 'server_complete_call'

_SUCCESS_CALL_FRACTION = 1.0 / 8.0


class _State(object):

  def __init__(self):
    self.condition = threading.Condition()
    self.handlers_released = False
    self.parked_handlers = 0
    self.handled_rpcs = 0


def _is_cancellation_event(event):
  return (
      event.tag is _RECEIVE_CLOSE_ON_SERVER_TAG and
      event.batch_operations[0].received_cancelled)


class _Handler(object):

  def __init__(self, state, completion_queue, rpc_event):
    self._state = state
    self._lock = threading.Lock()
    self._completion_queue = completion_queue
    self._call = rpc_event.operation_call

  def __call__(self):
    with self._state.condition:
      self._state.parked_handlers += 1
      if self._state.parked_handlers == test_constants.THREAD_CONCURRENCY:
        self._state.condition.notify_all()
      while not self._state.handlers_released:
        self._state.condition.wait()

    with self._lock:
      self._call.start_batch(
          cygrpc.Operations(
              (cygrpc.operation_receive_close_on_server(_EMPTY_FLAGS),)),
          _RECEIVE_CLOSE_ON_SERVER_TAG)
      self._call.start_batch(
          cygrpc.Operations((cygrpc.operation_receive_message(_EMPTY_FLAGS),)),
          _RECEIVE_MESSAGE_TAG)
    first_event = self._completion_queue.poll()
    if _is_cancellation_event(first_event):
      self._completion_queue.poll()
    else:
      with self._lock:
        operations = (
            cygrpc.operation_send_initial_metadata(
                _EMPTY_METADATA, _EMPTY_FLAGS),
            cygrpc.operation_send_message(b'\x79\x57', _EMPTY_FLAGS),
            cygrpc.operation_send_status_from_server(
                _EMPTY_METADATA, cygrpc.StatusCode.ok, b'test details!',
                _EMPTY_FLAGS),
        )
        self._call.start_batch(
            cygrpc.Operations(operations), _SERVER_COMPLETE_CALL_TAG)
      self._completion_queue.poll()
      self._completion_queue.poll()


def _serve(state, server, server_completion_queue, thread_pool):
  for _ in range(test_constants.RPC_CONCURRENCY):
    call_completion_queue = cygrpc.CompletionQueue()
    server.request_call(
        call_completion_queue, server_completion_queue, _REQUEST_CALL_TAG)
    rpc_event = server_completion_queue.poll()
    thread_pool.submit(_Handler(state, call_completion_queue, rpc_event))
    with state.condition:
      state.handled_rpcs += 1
      if test_constants.RPC_CONCURRENCY <= state.handled_rpcs:
        state.condition.notify_all()
  server_completion_queue.poll()


class _QueueDriver(object):

  def __init__(self, condition, completion_queue, due):
    self._condition = condition
    self._completion_queue = completion_queue
    self._due = due
    self._events = []
    self._returned = False

  def start(self):
    def in_thread():
      while True:
        event = self._completion_queue.poll()
        with self._condition:
          self._events.append(event)
          self._due.remove(event.tag)
          self._condition.notify_all()
          if not self._due:
            self._returned = True
            return
    thread = threading.Thread(target=in_thread)
    thread.start()

  def events(self, at_least):
    with self._condition:
      while len(self._events) < at_least:
        self._condition.wait()
      return tuple(self._events)


class CancelManyCallsTest(unittest.TestCase):

  def testCancelManyCalls(self):
    server_thread_pool = logging_pool.pool(test_constants.THREAD_CONCURRENCY)

    server_completion_queue = cygrpc.CompletionQueue()
    server = cygrpc.Server()
    server.register_completion_queue(server_completion_queue)
    port = server.add_http2_port('[::]:0')
    server.start()
    channel = cygrpc.Channel('localhost:{}'.format(port))

    state = _State()

    server_thread_args = (
        state, server, server_completion_queue, server_thread_pool,)
    server_thread = threading.Thread(target=_serve, args=server_thread_args)
    server_thread.start()

    client_condition = threading.Condition()
    client_due = set()
    client_completion_queue = cygrpc.CompletionQueue()
    client_driver = _QueueDriver(
        client_condition, client_completion_queue, client_due)
    client_driver.start()

    with client_condition:
      client_calls = []
      for index in range(test_constants.RPC_CONCURRENCY):
        client_call = channel.create_call(
            None, _EMPTY_FLAGS, client_completion_queue, b'/twinkies', None,
            _INFINITE_FUTURE)
        operations = (
            cygrpc.operation_send_initial_metadata(
                _EMPTY_METADATA, _EMPTY_FLAGS),
            cygrpc.operation_send_message(b'\x45\x56', _EMPTY_FLAGS),
            cygrpc.operation_send_close_from_client(_EMPTY_FLAGS),
            cygrpc.operation_receive_initial_metadata(_EMPTY_FLAGS),
            cygrpc.operation_receive_message(_EMPTY_FLAGS),
            cygrpc.operation_receive_status_on_client(_EMPTY_FLAGS),
        )
        tag = 'client_complete_call_{0:04d}_tag'.format(index)
        client_call.start_batch(cygrpc.Operations(operations), tag)
        client_due.add(tag)
        client_calls.append(client_call)

    with state.condition:
      while True:
        if state.parked_handlers < test_constants.THREAD_CONCURRENCY:
          state.condition.wait()
        elif state.handled_rpcs < test_constants.RPC_CONCURRENCY:
          state.condition.wait()
        else:
          state.handlers_released = True
          state.condition.notify_all()
          break

    client_driver.events(
        test_constants.RPC_CONCURRENCY * _SUCCESS_CALL_FRACTION)
    with client_condition:
      for client_call in client_calls:
        client_call.cancel()

    with state.condition:
      server.shutdown(server_completion_queue, _SERVER_SHUTDOWN_TAG)


if __name__ == '__main__':
  unittest.main(verbosity=2)
