| /* |
| * |
| * Copyright 2015 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| #ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_H |
| #define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_H |
| |
| #include "src/core/ext/filters/client_channel/subchannel.h" |
| #include "src/core/lib/iomgr/polling_entity.h" |
| #include "src/core/lib/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 struct grpc_lb_policy_args grpc_lb_policy_args; |
| |
| #ifndef NDEBUG |
| extern grpc_tracer_flag grpc_trace_lb_policy_refcount; |
| #endif |
| |
| 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; |
| /* combiner under which lb_policy actions take place */ |
| grpc_combiner *combiner; |
| }; |
| |
| /** Extra arguments for an LB pick */ |
| typedef struct grpc_lb_policy_pick_args { |
| /** Initial metadata associated with the picking call. */ |
| grpc_metadata_batch *initial_metadata; |
| /** Bitmask used for selective cancelling. See \a |
| * grpc_lb_policy_cancel_picks() and \a GRPC_INITIAL_METADATA_* in |
| * grpc_types.h */ |
| uint32_t initial_metadata_flags; |
| /** Storage for LB token in \a initial_metadata, or NULL if not used */ |
| grpc_linked_mdelem *lb_token_mdelem_storage; |
| } grpc_lb_policy_pick_args; |
| |
| struct grpc_lb_policy_vtable { |
| void (*destroy)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy); |
| void (*shutdown_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy); |
| |
| /** \see grpc_lb_policy_pick */ |
| int (*pick_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy, |
| const grpc_lb_policy_pick_args *pick_args, |
| grpc_connected_subchannel **target, |
| grpc_call_context_element *context, void **user_data, |
| grpc_closure *on_complete); |
| |
| /** \see grpc_lb_policy_cancel_pick */ |
| void (*cancel_pick_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy, |
| grpc_connected_subchannel **target, |
| grpc_error *error); |
| |
| /** \see grpc_lb_policy_cancel_picks */ |
| void (*cancel_picks_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy, |
| uint32_t initial_metadata_flags_mask, |
| uint32_t initial_metadata_flags_eq, |
| grpc_error *error); |
| |
| /** \see grpc_lb_policy_ping_one */ |
| void (*ping_one_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy, |
| grpc_closure *closure); |
| |
| /** Try to enter a READY connectivity state */ |
| void (*exit_idle_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy); |
| |
| /** check the current connectivity of the lb_policy */ |
| grpc_connectivity_state (*check_connectivity_locked)( |
| grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy, |
| grpc_error **connectivity_error); |
| |
| /** call notify when the connectivity state of a channel changes from *state. |
| Updates *state with the new state of the policy. Calling with a NULL \a |
| state cancels the subscription. */ |
| void (*notify_on_state_change_locked)(grpc_exec_ctx *exec_ctx, |
| grpc_lb_policy *policy, |
| grpc_connectivity_state *state, |
| grpc_closure *closure); |
| |
| void (*update_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy, |
| const grpc_lb_policy_args *args); |
| }; |
| |
| #ifndef NDEBUG |
| |
| /* Strong references: the policy will shutdown when they reach zero */ |
| #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)) |
| |
| /* Weak references: they don't prevent the shutdown of the LB policy. When no |
| * strong references are left but there are still weak ones, shutdown is called. |
| * Once the weak reference also reaches zero, the LB policy is destroyed. */ |
| #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, |
| grpc_combiner *combiner); |
| |
| /** Finds an appropriate subchannel for a call, based on \a pick_args. |
| |
| \a target will be set to the selected subchannel, or NULL on failure |
| or when the LB policy decides to drop the call. |
| |
| Upon success, \a user_data will be set to whatever opaque information |
| may need to be propagated from the LB policy, or NULL if not needed. |
| \a context will be populated with context to pass to the subchannel |
| call, if needed. |
| |
| If the pick succeeds and a result is known immediately, a non-zero |
| value will be returned. Otherwise, \a on_complete will be invoked |
| once the pick is complete with its error argument set to indicate |
| success or failure. |
| |
| Any IO should be done under the \a interested_parties \a grpc_pollset_set |
| in the \a grpc_lb_policy struct. */ |
| int grpc_lb_policy_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy, |
| const grpc_lb_policy_pick_args *pick_args, |
| grpc_connected_subchannel **target, |
| grpc_call_context_element *context, |
| void **user_data, grpc_closure *on_complete); |
| |
| /** Perform a connected subchannel ping (see \a grpc_connected_subchannel_ping) |
| against one of the connected subchannels managed by \a policy. */ |
| void grpc_lb_policy_ping_one_locked(grpc_exec_ctx *exec_ctx, |
| grpc_lb_policy *policy, |
| grpc_closure *closure); |
| |
| /** Cancel picks for \a target. |
| The \a on_complete callback of the pending picks will be invoked with \a |
| *target set to NULL. */ |
| void grpc_lb_policy_cancel_pick_locked(grpc_exec_ctx *exec_ctx, |
| grpc_lb_policy *policy, |
| grpc_connected_subchannel **target, |
| grpc_error *error); |
| |
| /** Cancel all pending picks for which their \a initial_metadata_flags (as given |
| in the call to \a grpc_lb_policy_pick) matches \a initial_metadata_flags_eq |
| when AND'd with \a initial_metadata_flags_mask */ |
| void grpc_lb_policy_cancel_picks_locked(grpc_exec_ctx *exec_ctx, |
| grpc_lb_policy *policy, |
| uint32_t initial_metadata_flags_mask, |
| uint32_t initial_metadata_flags_eq, |
| grpc_error *error); |
| |
| /** Try to enter a READY connectivity state */ |
| void grpc_lb_policy_exit_idle_locked(grpc_exec_ctx *exec_ctx, |
| grpc_lb_policy *policy); |
| |
| /* Call notify when the connectivity state of a channel changes from \a *state. |
| * Updates \a *state with the new state of the policy */ |
| void grpc_lb_policy_notify_on_state_change_locked( |
| grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy, |
| grpc_connectivity_state *state, grpc_closure *closure); |
| |
| grpc_connectivity_state grpc_lb_policy_check_connectivity_locked( |
| grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy, |
| grpc_error **connectivity_error); |
| |
| /** Update \a policy with \a lb_policy_args. */ |
| void grpc_lb_policy_update_locked(grpc_exec_ctx *exec_ctx, |
| grpc_lb_policy *policy, |
| const grpc_lb_policy_args *lb_policy_args); |
| |
| #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_H */ |