Initial checkin of gRPC to third_party/

third_party/grpc/src/core/client_config/lb_policy.h

Index: third_party/grpc/src/core/client_config/lb_policy.h
diff --git a/third_party/grpc/src/core/client_config/lb_policy.h b/third_party/grpc/src/core/client_config/lb_policy.h
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+/*
+ *
+ * Copyright 2015-2016, 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_CLIENT_CONFIG_LB_POLICY_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_LB_POLICY_H
+
+#include "src/core/client_config/subchannel.h"
+#include "src/core/transport/connectivity_state.h"
+
+/** A load balancing policy: specified by a vtable and a struct (which
+    is expected to be extended to contain some parameters) */
+typedef struct grpc_lb_policy grpc_lb_policy;
+typedef struct grpc_lb_policy_vtable grpc_lb_policy_vtable;
+
+typedef void (*grpc_lb_completion)(void *cb_arg, grpc_subchannel *subchannel,
+                                   grpc_status_code status, const char *errmsg);
+
+struct grpc_lb_policy {
+  const grpc_lb_policy_vtable *vtable;
+  gpr_atm ref_pair;
+  /* owned pointer to interested parties in load balancing decisions */
+  grpc_pollset_set *interested_parties;
+};
+
+struct grpc_lb_policy_vtable {
+  void (*destroy)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
+
+  void (*shutdown)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
+
+  /** implement grpc_lb_policy_pick */
+  int (*pick)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+              grpc_pollset *pollset, grpc_metadata_batch *initial_metadata,
+              grpc_connected_subchannel **target, grpc_closure *on_complete);
+  void (*cancel_pick)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                      grpc_connected_subchannel **target);
+
+  void (*ping_one)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                   grpc_closure *closure);
+
+  /** try to enter a READY connectivity state */
+  void (*exit_idle)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
+
+  /** check the current connectivity of the lb_policy */
+  grpc_connectivity_state (*check_connectivity)(grpc_exec_ctx *exec_ctx,
+                                                grpc_lb_policy *policy);
+
+  /** call notify when the connectivity state of a channel changes from *state.
+      Updates *state with the new state of the policy */
+  void (*notify_on_state_change)(grpc_exec_ctx *exec_ctx,
+                                 grpc_lb_policy *policy,
+                                 grpc_connectivity_state *state,
+                                 grpc_closure *closure);
+};
+
+/*#define GRPC_LB_POLICY_REFCOUNT_DEBUG*/
+#ifdef GRPC_LB_POLICY_REFCOUNT_DEBUG
+#define GRPC_LB_POLICY_REF(p, r) \
+  grpc_lb_policy_ref((p), __FILE__, __LINE__, (r))
+#define GRPC_LB_POLICY_UNREF(exec_ctx, p, r) \
+  grpc_lb_policy_unref((exec_ctx), (p), __FILE__, __LINE__, (r))
+#define GRPC_LB_POLICY_WEAK_REF(p, r) \
+  grpc_lb_policy_weak_ref((p), __FILE__, __LINE__, (r))
+#define GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, p, r) \
+  grpc_lb_policy_weak_unref((exec_ctx), (p), __FILE__, __LINE__, (r))
+void grpc_lb_policy_ref(grpc_lb_policy *policy, const char *file, int line,
+                        const char *reason);
+void grpc_lb_policy_unref(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                          const char *file, int line, const char *reason);
+void grpc_lb_policy_weak_ref(grpc_lb_policy *policy, const char *file, int line,
+                             const char *reason);
+void grpc_lb_policy_weak_unref(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                               const char *file, int line, const char *reason);
+#else
+#define GRPC_LB_POLICY_REF(p, r) grpc_lb_policy_ref((p))
+#define GRPC_LB_POLICY_UNREF(cl, p, r) grpc_lb_policy_unref((cl), (p))
+#define GRPC_LB_POLICY_WEAK_REF(p, r) grpc_lb_policy_weak_ref((p))
+#define GRPC_LB_POLICY_WEAK_UNREF(cl, p, r) grpc_lb_policy_weak_unref((cl), (p))
+void grpc_lb_policy_ref(grpc_lb_policy *policy);
+void grpc_lb_policy_unref(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
+void grpc_lb_policy_weak_ref(grpc_lb_policy *policy);
+void grpc_lb_policy_weak_unref(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
+#endif
+
+/** called by concrete implementations to initialize the base struct */
+void grpc_lb_policy_init(grpc_lb_policy *policy,
+                         const grpc_lb_policy_vtable *vtable);
+
+/** Given initial metadata in \a initial_metadata, find an appropriate
+    target for this rpc, and 'return' it by calling \a on_complete after setting
+    \a target.
+    Picking can be asynchronous. Any IO should be done under \a pollset. */
+int grpc_lb_policy_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                        grpc_pollset *pollset,
+                        grpc_metadata_batch *initial_metadata,
+                        grpc_connected_subchannel **target,
+                        grpc_closure *on_complete);
+
+void grpc_lb_policy_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                             grpc_closure *closure);
+
+void grpc_lb_policy_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                                grpc_connected_subchannel **target);
+
+void grpc_lb_policy_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
+
+void grpc_lb_policy_notify_on_state_change(grpc_exec_ctx *exec_ctx,
+                                           grpc_lb_policy *policy,
+                                           grpc_connectivity_state *state,
+                                           grpc_closure *closure);
+
+grpc_connectivity_state grpc_lb_policy_check_connectivity(
+    grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
+
+#endif /* GRPC_INTERNAL_CORE_CONFIG_LB_POLICY_H */