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"""In-memory implementations of base layer interfaces."""
import threading
from grpc.framework.base import _constants
from grpc.framework.base import interfaces
from grpc.framework.foundation import callable_util
class _Serializer(object):
"""A utility for serializing values that may arrive concurrently."""
def __init__(self, pool):
self._lock = threading.Lock()
self._pool = pool
self._sink = None
self._spinning = False
self._values = []
def _spin(self, sink, value):
while True:
sink(value)
with self._lock:
if self._sink is None or not self._values:
self._spinning = False
return
else:
sink, value = self._sink, self._values.pop(0)
def set_sink(self, sink):
with self._lock:
self._sink = sink
if sink is not None and self._values and not self._spinning:
self._spinning = True
self._pool.submit(
callable_util.with_exceptions_logged(
self._spin, _constants.INTERNAL_ERROR_LOG_MESSAGE),
sink, self._values.pop(0))
def add_value(self, value):
with self._lock:
if self._sink and not self._spinning:
self._spinning = True
self._pool.submit(
callable_util.with_exceptions_logged(
self._spin, _constants.INTERNAL_ERROR_LOG_MESSAGE),
self._sink, value)
else:
self._values.append(value)
[docs]class Link(interfaces.ForeLink, interfaces.RearLink):
"""A trivial implementation of interfaces.ForeLink and interfaces.RearLink."""
def __init__(self, pool):
"""Constructor.
Args:
pool: A thread pool to be used for serializing ticket exchange in each
direction.
"""
self._front_to_back = _Serializer(pool)
self._back_to_front = _Serializer(pool)
[docs] def join_fore_link(self, fore_link):
"""See interfaces.RearLink.join_fore_link for specification."""
self._back_to_front.set_sink(fore_link.accept_back_to_front_ticket)
[docs] def join_rear_link(self, rear_link):
"""See interfaces.ForeLink.join_rear_link for specification."""
self._front_to_back.set_sink(rear_link.accept_front_to_back_ticket)
[docs] def accept_front_to_back_ticket(self, ticket):
"""See interfaces.ForeLink.accept_front_to_back_ticket for specification."""
self._front_to_back.add_value(ticket)
[docs] def accept_back_to_front_ticket(self, ticket):
"""See interfaces.RearLink.accept_back_to_front_ticket for specification."""
self._back_to_front.add_value(ticket)