diff options
Diffstat (limited to 'src/core/ext/filters/client_channel/lb_policy.h')
| -rw-r--r-- | src/core/ext/filters/client_channel/lb_policy.h | 94 |
1 files changed, 42 insertions, 52 deletions
diff --git a/src/core/ext/filters/client_channel/lb_policy.h b/src/core/ext/filters/client_channel/lb_policy.h index 3572c97ed1..30660cb83d 100644 --- a/src/core/ext/filters/client_channel/lb_policy.h +++ b/src/core/ext/filters/client_channel/lb_policy.h @@ -20,6 +20,7 @@ #define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_H #include "src/core/ext/filters/client_channel/subchannel.h" +#include "src/core/lib/gprpp/ref_counted_ptr.h" #include "src/core/lib/iomgr/polling_entity.h" #include "src/core/lib/transport/connectivity_state.h" @@ -33,7 +34,7 @@ extern grpc_core::DebugOnlyTraceFlag grpc_trace_lb_policy_refcount; struct grpc_lb_policy { const grpc_lb_policy_vtable* vtable; - gpr_atm ref_pair; + gpr_refcount refs; /* owned pointer to interested parties in load balancing decisions */ grpc_pollset_set* interested_parties; /* combiner under which lb_policy actions take place */ @@ -42,32 +43,42 @@ struct grpc_lb_policy { grpc_closure* request_reresolution; }; -/** Extra arguments for an LB pick */ -typedef struct grpc_lb_policy_pick_args { - /** Initial metadata associated with the picking call. */ +/// State used for an LB pick. +typedef struct grpc_lb_policy_pick_state { + /// 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 */ + /// 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; + /// Storage for LB token in \a initial_metadata, or NULL if not used. + grpc_linked_mdelem lb_token_mdelem_storage; + /// Closure to run when pick is complete, if not completed synchronously. + grpc_closure* on_complete; + /// Will be set to the selected subchannel, or nullptr on failure or when + /// the LB policy decides to drop the call. + grpc_core::RefCountedPtr<grpc_core::ConnectedSubchannel> connected_subchannel; + /// Will be populated with context to pass to the subchannel call, if needed. + grpc_call_context_element subchannel_call_context[GRPC_CONTEXT_COUNT]; + /// 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. + void** user_data; + /// Next pointer. For internal use by LB policy. + struct grpc_lb_policy_pick_state* next; +} grpc_lb_policy_pick_state; struct grpc_lb_policy_vtable { void (*destroy)(grpc_lb_policy* policy); - void (*shutdown_locked)(grpc_lb_policy* policy); + + /// \see grpc_lb_policy_shutdown_locked(). + void (*shutdown_locked)(grpc_lb_policy* policy, grpc_lb_policy* new_policy); /** \see grpc_lb_policy_pick */ - int (*pick_locked)(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); + int (*pick_locked)(grpc_lb_policy* policy, grpc_lb_policy_pick_state* pick); /** \see grpc_lb_policy_cancel_pick */ void (*cancel_pick_locked)(grpc_lb_policy* policy, - grpc_connected_subchannel** target, + grpc_lb_policy_pick_state* pick, grpc_error* error); /** \see grpc_lb_policy_cancel_picks */ @@ -103,37 +114,19 @@ struct grpc_lb_policy_vtable { }; #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(p, r) \ grpc_lb_policy_unref((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(p, r) \ - grpc_lb_policy_weak_unref((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_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_lb_policy* policy, const char* file, - int line, const char* reason); -#else +#else // !NDEBUG #define GRPC_LB_POLICY_REF(p, r) grpc_lb_policy_ref((p)) #define GRPC_LB_POLICY_UNREF(p, r) grpc_lb_policy_unref((p)) -#define GRPC_LB_POLICY_WEAK_REF(p, r) grpc_lb_policy_weak_ref((p)) -#define GRPC_LB_POLICY_WEAK_UNREF(p, r) grpc_lb_policy_weak_unref((p)) void grpc_lb_policy_ref(grpc_lb_policy* policy); void grpc_lb_policy_unref(grpc_lb_policy* policy); -void grpc_lb_policy_weak_ref(grpc_lb_policy* policy); -void grpc_lb_policy_weak_unref(grpc_lb_policy* policy); #endif /** called by concrete implementations to initialize the base struct */ @@ -141,40 +134,37 @@ 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. +/// Shuts down \a policy. +/// If \a new_policy is non-null, any pending picks will be restarted +/// on that policy; otherwise, they will be failed. +void grpc_lb_policy_shutdown_locked(grpc_lb_policy* policy, + grpc_lb_policy* new_policy); - 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. +/** Finds an appropriate subchannel for a call, based on data in \a pick. + \a pick must remain alive until the pick is complete. If the pick succeeds and a result is known immediately, a non-zero - value will be returned. Otherwise, \a on_complete will be invoked + value will be returned. Otherwise, \a pick->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_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); + grpc_lb_policy_pick_state* pick); -/** Perform a connected subchannel ping (see \a grpc_connected_subchannel_ping) +/** Perform a connected subchannel ping (see \a + grpc_core::ConnectedSubchannel::Ping) against one of the connected subchannels managed by \a policy. */ void grpc_lb_policy_ping_one_locked(grpc_lb_policy* policy, grpc_closure* on_initiate, grpc_closure* on_ack); -/** Cancel picks for \a target. +/** Cancel picks for \a pick. 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_lb_policy* policy, - grpc_connected_subchannel** target, + grpc_lb_policy_pick_state* pick, grpc_error* error); /** Cancel all pending picks for which their \a initial_metadata_flags (as given |