Initial checkin of gRPC to third_party/

third_party/grpc/src/python/grpcio/grpc/_adapter/fore.py

Index: third_party/grpc/src/python/grpcio/grpc/_adapter/fore.py
diff --git a/third_party/grpc/src/python/grpcio/grpc/_adapter/fore.py b/third_party/grpc/src/python/grpcio/grpc/_adapter/fore.py
new file mode 100644
index 0000000000000000000000000000000000000000..acdd69c4206b7bea1c8c53d7ee00ef2ba06c936e
--- /dev/null
+++ b/third_party/grpc/src/python/grpcio/grpc/_adapter/fore.py
@@ -0,0 +1,363 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""The RPC-service-side bridge between RPC Framework and GRPC-on-the-wire."""
+
+import enum
+import logging
+import threading
+import time
+
+from grpc._adapter import _common
+from grpc._adapter import _intermediary_low as _low
+from grpc.framework.base import interfaces as base_interfaces
+from grpc.framework.base import null
+from grpc.framework.foundation import activated
+from grpc.framework.foundation import logging_pool
+
+_THREAD_POOL_SIZE = 10
+
+
+@enum.unique
+class _LowWrite(enum.Enum):
+  """The possible categories of low-level write state."""
+
+  OPEN = 'OPEN'
+  ACTIVE = 'ACTIVE'
+  CLOSED = 'CLOSED'
+
+
+def _write(call, rpc_state, payload):
+  serialized_payload = rpc_state.serializer(payload)
+  if rpc_state.write.low is _LowWrite.OPEN:
+    call.write(serialized_payload, call, 0)
+    rpc_state.write.low = _LowWrite.ACTIVE
+  else:
+    rpc_state.write.pending.append(serialized_payload)
+
+
+def _status(call, rpc_state):
+  call.status(_low.Status(_low.Code.OK, ''), call)
+  rpc_state.write.low = _LowWrite.CLOSED
+
+
+class ForeLink(base_interfaces.ForeLink, activated.Activated):
+  """A service-side bridge between RPC Framework and the C-ish _low code."""
+
+  def __init__(
+      self, pool, request_deserializers, response_serializers,
+      root_certificates, key_chain_pairs, port=None):
+    """Constructor.
+
+    Args:
+      pool: A thread pool.
+      request_deserializers: A dict from RPC method names to request object
+        deserializer behaviors.
+      response_serializers: A dict from RPC method names to response object
+        serializer behaviors.
+      root_certificates: The PEM-encoded client root certificates as a
+        bytestring or None.
+      key_chain_pairs: A sequence of PEM-encoded private key-certificate chain
+        pairs.
+      port: The port on which to serve, or None to have a port selected
+        automatically.
+    """
+    self._condition = threading.Condition()
+    self._pool = pool
+    self._request_deserializers = request_deserializers
+    self._response_serializers = response_serializers
+    self._root_certificates = root_certificates
+    self._key_chain_pairs = key_chain_pairs
+    self._requested_port = port
+
+    self._rear_link = null.NULL_REAR_LINK
+    self._completion_queue = None
+    self._server = None
+    self._rpc_states = {}
+    self._spinning = False
+    self._port = None
+
+  def _on_stop_event(self):
+    self._spinning = False
+    self._condition.notify_all()
+
+  def _on_service_acceptance_event(self, event, server):
+    """Handle a service invocation event."""
+    service_acceptance = event.service_acceptance
+    if service_acceptance is None:
+      return
+
+    call = service_acceptance.call
+    call.accept(self._completion_queue, call)
+    # TODO(nathaniel): Metadata support.
+    call.premetadata()
+    call.read(call)
+    method = service_acceptance.method
+
+    self._rpc_states[call] = _common.CommonRPCState(
+        _common.WriteState(_LowWrite.OPEN, _common.HighWrite.OPEN, []), 1,
+        self._request_deserializers[method],
+        self._response_serializers[method])
+
+    ticket = base_interfaces.FrontToBackTicket(
+        call, 0, base_interfaces.FrontToBackTicket.Kind.COMMENCEMENT, method,
+        base_interfaces.ServicedSubscription.Kind.FULL, None, None,
+        service_acceptance.deadline - time.time())
+    self._rear_link.accept_front_to_back_ticket(ticket)
+
+    server.service(None)
+
+  def _on_read_event(self, event):
+    """Handle data arriving during an RPC."""
+    call = event.tag
+    rpc_state = self._rpc_states.get(call, None)
+    if rpc_state is None:
+      return
+
+    sequence_number = rpc_state.sequence_number
+    rpc_state.sequence_number += 1
+    if event.bytes is None:
+      ticket = base_interfaces.FrontToBackTicket(
+          call, sequence_number,
+          base_interfaces.FrontToBackTicket.Kind.COMPLETION, None, None, None,
+          None, None)
+    else:
+      call.read(call)
+      ticket = base_interfaces.FrontToBackTicket(
+          call, sequence_number,
+          base_interfaces.FrontToBackTicket.Kind.CONTINUATION, None, None,
+          None, rpc_state.deserializer(event.bytes), None)
+
+    self._rear_link.accept_front_to_back_ticket(ticket)
+
+  def _on_write_event(self, event):
+    call = event.tag
+    rpc_state = self._rpc_states.get(call, None)
+    if rpc_state is None:
+      return
+
+    if rpc_state.write.pending:
+      serialized_payload = rpc_state.write.pending.pop(0)
+      call.write(serialized_payload, call, 0)
+    elif rpc_state.write.high is _common.HighWrite.CLOSED:
+      _status(call, rpc_state)
+    else:
+      rpc_state.write.low = _LowWrite.OPEN
+
+  def _on_complete_event(self, event):
+    if not event.complete_accepted:
+      logging.error('Complete not accepted! %s', (event,))
+      call = event.tag
+      rpc_state = self._rpc_states.pop(call, None)
+      if rpc_state is None:
+        return
+
+      sequence_number = rpc_state.sequence_number
+      rpc_state.sequence_number += 1
+      ticket = base_interfaces.FrontToBackTicket(
+          call, sequence_number,
+          base_interfaces.FrontToBackTicket.Kind.TRANSMISSION_FAILURE, None,
+          None, None, None, None)
+      self._rear_link.accept_front_to_back_ticket(ticket)
+
+  def _on_finish_event(self, event):
+    """Handle termination of an RPC."""
+    call = event.tag
+    rpc_state = self._rpc_states.pop(call, None)
+    if rpc_state is None:
+      return
+
+    code = event.status.code
+    if code is _low.Code.OK:
+      return
+
+    sequence_number = rpc_state.sequence_number
+    rpc_state.sequence_number += 1
+    if code is _low.Code.CANCELLED:
+      ticket = base_interfaces.FrontToBackTicket(
+          call, sequence_number,
+          base_interfaces.FrontToBackTicket.Kind.CANCELLATION, None, None,
+          None, None, None)
+    elif code is _low.Code.DEADLINE_EXCEEDED:
+      ticket = base_interfaces.FrontToBackTicket(
+          call, sequence_number,
+          base_interfaces.FrontToBackTicket.Kind.EXPIRATION, None, None, None,
+          None, None)
+    else:
+      # TODO(nathaniel): Better mapping of codes to ticket-categories
+      ticket = base_interfaces.FrontToBackTicket(
+          call, sequence_number,
+          base_interfaces.FrontToBackTicket.Kind.TRANSMISSION_FAILURE, None,
+          None, None, None, None)
+    self._rear_link.accept_front_to_back_ticket(ticket)
+
+  def _spin(self, completion_queue, server):
+    while True:
+      event = completion_queue.get(None)
+
+      with self._condition:
+        if event.kind is _low.Event.Kind.STOP:
+          self._on_stop_event()
+          return
+        elif self._server is None:
+          continue
+        elif event.kind is _low.Event.Kind.SERVICE_ACCEPTED:
+          self._on_service_acceptance_event(event, server)
+        elif event.kind is _low.Event.Kind.READ_ACCEPTED:
+          self._on_read_event(event)
+        elif event.kind is _low.Event.Kind.WRITE_ACCEPTED:
+          self._on_write_event(event)
+        elif event.kind is _low.Event.Kind.COMPLETE_ACCEPTED:
+          self._on_complete_event(event)
+        elif event.kind is _low.Event.Kind.FINISH:
+          self._on_finish_event(event)
+        else:
+          logging.error('Illegal event! %s', (event,))
+
+  def _continue(self, call, payload):
+    rpc_state = self._rpc_states.get(call, None)
+    if rpc_state is None:
+      return
+
+    _write(call, rpc_state, payload)
+
+  def _complete(self, call, payload):
+    """Handle completion of the writes of an RPC."""
+    rpc_state = self._rpc_states.get(call, None)
+    if rpc_state is None:
+      return
+
+    if rpc_state.write.low is _LowWrite.OPEN:
+      if payload is None:
+        _status(call, rpc_state)
+      else:
+        _write(call, rpc_state, payload)
+    elif rpc_state.write.low is _LowWrite.ACTIVE:
+      if payload is not None:
+        rpc_state.write.pending.append(rpc_state.serializer(payload))
+    else:
+      raise ValueError('Called to complete after having already completed!')
+    rpc_state.write.high = _common.HighWrite.CLOSED
+
+  def _cancel(self, call):
+    call.cancel()
+    self._rpc_states.pop(call, None)
+
+  def join_rear_link(self, rear_link):
+    """See base_interfaces.ForeLink.join_rear_link for specification."""
+    self._rear_link = null.NULL_REAR_LINK if rear_link is None else rear_link
+
+  def _start(self):
+    """Starts this ForeLink.
+
+    This method must be called before attempting to exchange tickets with this
+    object.
+    """
+    with self._condition:
+      address = '[::]:%d' % (
+          0 if self._requested_port is None else self._requested_port)
+      self._completion_queue = _low.CompletionQueue()
+      if self._root_certificates is None and not self._key_chain_pairs:
+        self._server = _low.Server(self._completion_queue)
+        self._port = self._server.add_http2_addr(address)
+      else:
+        server_credentials = _low.ServerCredentials(
+          self._root_certificates, self._key_chain_pairs, False)
+        self._server = _low.Server(self._completion_queue)
+        self._port = self._server.add_secure_http2_addr(
+            address, server_credentials)
+      self._server.start()
+
+      self._server.service(None)
+
+      self._pool.submit(self._spin, self._completion_queue, self._server)
+      self._spinning = True
+
+      return self
+
+  # TODO(nathaniel): Expose graceful-shutdown semantics in which this object
+  # enters a state in which it finishes ongoing RPCs but refuses new ones.
+  def _stop(self):
+    """Stops this ForeLink.
+
+    This method must be called for proper termination of this object, and no
+    attempts to exchange tickets with this object may be made after this method
+    has been called.
+    """
+    with self._condition:
+      self._server.stop()
+      # TODO(nathaniel): Yep, this is weird. Deleting a server shouldn't have a
+      # behaviorally significant side-effect.
+      self._server = None
+      self._completion_queue.stop()
+
+      while self._spinning:
+        self._condition.wait()
+
+      self._port = None
+
+  def __enter__(self):
+    """See activated.Activated.__enter__ for specification."""
+    return self._start()
+
+  def __exit__(self, exc_type, exc_val, exc_tb):
+    """See activated.Activated.__exit__ for specification."""
+    self._stop()
+    return False
+
+  def start(self):
+    """See activated.Activated.start for specification."""
+    return self._start()
+
+  def stop(self):
+    """See activated.Activated.stop for specification."""
+    self._stop()
+
+  def port(self):
+    """Identifies the port on which this ForeLink is servicing RPCs.
+
+    Returns:
+      The number of the port on which this ForeLink is servicing RPCs, or None
+        if this ForeLink is not currently activated and servicing RPCs.
+    """
+    with self._condition:
+      return self._port
+
+  def accept_back_to_front_ticket(self, ticket):
+    """See base_interfaces.ForeLink.accept_back_to_front_ticket for spec."""
+    with self._condition:
+      if self._server is None:
+        return
+
+      if ticket.kind is base_interfaces.BackToFrontTicket.Kind.CONTINUATION:
+        self._continue(ticket.operation_id, ticket.payload)
+      elif ticket.kind is base_interfaces.BackToFrontTicket.Kind.COMPLETION:
+        self._complete(ticket.operation_id, ticket.payload)
+      else:
+        self._cancel(ticket.operation_id)