Initial checkin of gRPC to third_party/

third_party/grpc/src/core/channel/subchannel_call_holder.h

Index: third_party/grpc/src/core/channel/subchannel_call_holder.h
diff --git a/third_party/grpc/src/core/channel/subchannel_call_holder.h b/third_party/grpc/src/core/channel/subchannel_call_holder.h
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+++ b/third_party/grpc/src/core/channel/subchannel_call_holder.h
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+/*
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CHANNEL_SUBCHANNEL_CALL_HOLDER_H
+#define GRPC_INTERNAL_CORE_CHANNEL_SUBCHANNEL_CALL_HOLDER_H
+
+#include "src/core/client_config/subchannel.h"
+
+/** Pick a subchannel for grpc_subchannel_call_holder;
+    Return 1 if subchannel is available immediately (in which case on_ready
+    should not be called), or 0 otherwise (in which case on_ready should be
+    called when the subchannel is available) */
+typedef int (*grpc_subchannel_call_holder_pick_subchannel)(
+    grpc_exec_ctx *exec_ctx, void *arg, grpc_metadata_batch *initial_metadata,
+    grpc_connected_subchannel **connected_subchannel, grpc_closure *on_ready);
+
+typedef enum {
+  GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING,
+  GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL
+} grpc_subchannel_call_holder_creation_phase;
+
+/** Wrapper for holding a pointer to grpc_subchannel_call, and the
+    associated machinery to create such a pointer.
+    Handles queueing of stream ops until a call object is ready, waiting
+    for initial metadata before trying to create a call object,
+    and handling cancellation gracefully.
+
+    Both the channel and uchannel filter use this as their call_data. */
+typedef struct grpc_subchannel_call_holder {
+  /** either 0 for no call, 1 for cancelled, or a pointer to a
+      grpc_subchannel_call */
+  gpr_atm subchannel_call;
+  /** Helper function to choose the subchannel on which to create
+      the call object. Channel filter delegates to the load
+      balancing policy (once it's ready); uchannel returns
+      immediately */
+  grpc_subchannel_call_holder_pick_subchannel pick_subchannel;
+  void *pick_subchannel_arg;
+
+  gpr_mu mu;
+
+  grpc_subchannel_call_holder_creation_phase creation_phase;
+  grpc_connected_subchannel *connected_subchannel;
+  grpc_pollset *pollset;
+
+  grpc_transport_stream_op *waiting_ops;
+  size_t waiting_ops_count;
+  size_t waiting_ops_capacity;
+
+  grpc_closure next_step;
+
+  grpc_call_stack *owning_call;
+} grpc_subchannel_call_holder;
+
+void grpc_subchannel_call_holder_init(
+    grpc_subchannel_call_holder *holder,
+    grpc_subchannel_call_holder_pick_subchannel pick_subchannel,
+    void *pick_subchannel_arg, grpc_call_stack *owning_call);
+void grpc_subchannel_call_holder_destroy(grpc_exec_ctx *exec_ctx,
+                                         grpc_subchannel_call_holder *holder);
+
+void grpc_subchannel_call_holder_perform_op(grpc_exec_ctx *exec_ctx,
+                                            grpc_subchannel_call_holder *holder,
+                                            grpc_transport_stream_op *op);
+char *grpc_subchannel_call_holder_get_peer(grpc_exec_ctx *exec_ctx,
+                                           grpc_subchannel_call_holder *holder);
+
+#endif