Revert "Merge pull request #13970 from grpc/revert-13857-lb_policy_ref_simplification"
This reverts commit 61b32965bec11f4106c729bb0a428ff03d2d03ab, reversing
changes made to 2eb22fd67d73a210c1f41d79efcfe52285ccb2ec.
diff --git a/src/core/ext/filters/client_channel/lb_policy.h b/src/core/ext/filters/client_channel/lb_policy.h
index 3572c97..1176a05 100644
--- a/src/core/ext/filters/client_channel/lb_policy.h
+++ b/src/core/ext/filters/client_channel/lb_policy.h
@@ -33,7 +33,7 @@
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 +42,42 @@
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 NULL on failure or when
+ /// the LB policy decides to drop the call.
+ grpc_connected_subchannel* 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 +113,19 @@
};
#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 */
@@ -141,28 +133,24 @@
const grpc_lb_policy_vtable* vtable,
grpc_combiner* combiner);
-/** Finds an appropriate subchannel for a call, based on \a pick_args.
+/// 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);
- \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.
+/** 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)
against one of the connected subchannels managed by \a policy. */
@@ -170,11 +158,11 @@
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