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Diffstat (limited to 'src/core/ext/client_channel/lb_policy.h')
| -rw-r--r-- | src/core/ext/client_channel/lb_policy.h | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/src/core/ext/client_channel/lb_policy.h b/src/core/ext/client_channel/lb_policy.h new file mode 100644 index 0000000000..120c641edc --- /dev/null +++ b/src/core/ext/client_channel/lb_policy.h @@ -0,0 +1,202 @@ +/* + * + * 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_CORE_EXT_CLIENT_CHANNEL_LB_POLICY_H +#define GRPC_CORE_EXT_CLIENT_CHANNEL_LB_POLICY_H + +#include "src/core/ext/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 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; +}; + +/** 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; + /** Deadline for the call to the LB server */ + gpr_timespec deadline; +} grpc_lb_policy_pick_args; + +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); + + /** \see grpc_lb_policy_pick */ + int (*pick)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy, + const grpc_lb_policy_pick_args *pick_args, + grpc_connected_subchannel **target, void **user_data, + grpc_closure *on_complete); + + /** \see grpc_lb_policy_cancel_pick */ + void (*cancel_pick)(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)(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)(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, + 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)(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 + +/* 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); + +/** 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. + 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. + + 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(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy, + const grpc_lb_policy_pick_args *pick_args, + grpc_connected_subchannel **target, 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(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(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(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(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(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, + grpc_error **connectivity_error); + +#endif /* GRPC_CORE_EXT_CLIENT_CHANNEL_LB_POLICY_H */ |