Initial checkin of gRPC to third_party/

third_party/grpc/src/python/grpcio/grpc/framework/base/in_memory.py

Index: third_party/grpc/src/python/grpcio/grpc/framework/base/in_memory.py
diff --git a/third_party/grpc/src/python/grpcio/grpc/framework/base/in_memory.py b/third_party/grpc/src/python/grpcio/grpc/framework/base/in_memory.py
new file mode 100644
index 0000000000000000000000000000000000000000..c92d0bc663c557c984d24df575f104caa66bba3b
--- /dev/null
+++ b/third_party/grpc/src/python/grpcio/grpc/framework/base/in_memory.py
@@ -0,0 +1,108 @@
+# 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.
+
+"""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)
+
+
+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)
+
+  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)
+
+  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)
+
+  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)
+
+  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)