TLS session resumption support for Python clients

This change adds an experimental ssl_session_cache_lru function to the
Python API that returns an encapsulated grpc_ssl_session_cache (#14483).
Python clients may use this object as an argument for the
grpc.ssl_session_cache channel option if they wish to cache and resume
TLS sessions with a server.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/python/grpcio/grpc/_cython/_cygrpc/credentials.pyx.pxi b/src/python/grpcio/grpc/_cython/_cygrpc/credentials.pyx.pxi
index dff9097bf9..f4ccfbc016 100644
--- a/src/python/grpcio/grpc/_cython/_cygrpc/credentials.pyx.pxi
+++ b/src/python/grpcio/grpc/_cython/_cygrpc/credentials.pyx.pxi
@@ -17,6 +17,9 @@ cimport cpython
 import grpc
 import threading
 
+from libc.stdint cimport uintptr_t
+
+
 def _spawn_callback_in_thread(cb_func, args):
   threading.Thread(target=cb_func, args=args).start()
 
@@ -29,6 +32,7 @@ def set_async_callback_func(callback_func):
 def _spawn_callback_async(callback, args):
   async_callback_func(callback, args)
 
+
 cdef class CallCredentials:
 
   cdef grpc_call_credentials *c(self):
@@ -107,6 +111,21 @@ cdef class ChannelCredentials:
     raise NotImplementedError()
 
 
+cdef class SSLSessionCacheLRU:
+
+  def __cinit__(self, capacity):
+    grpc_init()
+    self._cache = grpc_ssl_session_cache_create_lru(capacity)
+
+  def __int__(self):
+    return <uintptr_t>self._cache
+
+  def __dealloc__(self):
+    if self._cache != NULL:
+        grpc_ssl_session_cache_destroy(self._cache)
+    grpc_shutdown()
+
+
 cdef class SSLChannelCredentials(ChannelCredentials):
 
   def __cinit__(self, pem_root_certificates, private_key, certificate_chain):