diff options
Diffstat (limited to 'src/core/ext/filters/client_channel/request_routing.cc')
| -rw-r--r-- | src/core/ext/filters/client_channel/request_routing.cc | 936 |
1 files changed, 936 insertions, 0 deletions
diff --git a/src/core/ext/filters/client_channel/request_routing.cc b/src/core/ext/filters/client_channel/request_routing.cc new file mode 100644 index 0000000000..f9a7e164e7 --- /dev/null +++ b/src/core/ext/filters/client_channel/request_routing.cc @@ -0,0 +1,936 @@ +/* + * + * 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. + * + */ + +#include <grpc/support/port_platform.h> + +#include "src/core/ext/filters/client_channel/request_routing.h" + +#include <inttypes.h> +#include <limits.h> +#include <stdbool.h> +#include <stdio.h> +#include <string.h> + +#include <grpc/support/alloc.h> +#include <grpc/support/log.h> +#include <grpc/support/string_util.h> +#include <grpc/support/sync.h> + +#include "src/core/ext/filters/client_channel/backup_poller.h" +#include "src/core/ext/filters/client_channel/http_connect_handshaker.h" +#include "src/core/ext/filters/client_channel/lb_policy_registry.h" +#include "src/core/ext/filters/client_channel/proxy_mapper_registry.h" +#include "src/core/ext/filters/client_channel/resolver_registry.h" +#include "src/core/ext/filters/client_channel/retry_throttle.h" +#include "src/core/ext/filters/client_channel/server_address.h" +#include "src/core/ext/filters/client_channel/subchannel.h" +#include "src/core/ext/filters/deadline/deadline_filter.h" +#include "src/core/lib/backoff/backoff.h" +#include "src/core/lib/channel/channel_args.h" +#include "src/core/lib/channel/connected_channel.h" +#include "src/core/lib/channel/status_util.h" +#include "src/core/lib/gpr/string.h" +#include "src/core/lib/gprpp/inlined_vector.h" +#include "src/core/lib/gprpp/manual_constructor.h" +#include "src/core/lib/iomgr/combiner.h" +#include "src/core/lib/iomgr/iomgr.h" +#include "src/core/lib/iomgr/polling_entity.h" +#include "src/core/lib/profiling/timers.h" +#include "src/core/lib/slice/slice_internal.h" +#include "src/core/lib/slice/slice_string_helpers.h" +#include "src/core/lib/surface/channel.h" +#include "src/core/lib/transport/connectivity_state.h" +#include "src/core/lib/transport/error_utils.h" +#include "src/core/lib/transport/metadata.h" +#include "src/core/lib/transport/metadata_batch.h" +#include "src/core/lib/transport/service_config.h" +#include "src/core/lib/transport/static_metadata.h" +#include "src/core/lib/transport/status_metadata.h" + +namespace grpc_core { + +// +// RequestRouter::Request::ResolverResultWaiter +// + +// Handles waiting for a resolver result. +// Used only for the first call on an idle channel. +class RequestRouter::Request::ResolverResultWaiter { + public: + explicit ResolverResultWaiter(Request* request) + : request_router_(request->request_router_), + request_(request), + tracer_enabled_(request_router_->tracer_->enabled()) { + if (tracer_enabled_) { + gpr_log(GPR_INFO, + "request_router=%p request=%p: deferring pick pending resolver " + "result", + request_router_, request); + } + // Add closure to be run when a resolver result is available. + GRPC_CLOSURE_INIT(&done_closure_, &DoneLocked, this, + grpc_combiner_scheduler(request_router_->combiner_)); + AddToWaitingList(); + // Set cancellation closure, so that we abort if the call is cancelled. + GRPC_CLOSURE_INIT(&cancel_closure_, &CancelLocked, this, + grpc_combiner_scheduler(request_router_->combiner_)); + grpc_call_combiner_set_notify_on_cancel(request->call_combiner_, + &cancel_closure_); + } + + private: + // Adds done_closure_ to + // request_router_->waiting_for_resolver_result_closures_. + void AddToWaitingList() { + grpc_closure_list_append( + &request_router_->waiting_for_resolver_result_closures_, &done_closure_, + GRPC_ERROR_NONE); + } + + // Invoked when a resolver result is available. + static void DoneLocked(void* arg, grpc_error* error) { + ResolverResultWaiter* self = static_cast<ResolverResultWaiter*>(arg); + RequestRouter* request_router = self->request_router_; + // If CancelLocked() has already run, delete ourselves without doing + // anything. Note that the call stack may have already been destroyed, + // so it's not safe to access anything in state_. + if (GPR_UNLIKELY(self->finished_)) { + if (self->tracer_enabled_) { + gpr_log(GPR_INFO, + "request_router=%p: call cancelled before resolver result", + request_router); + } + Delete(self); + return; + } + // Otherwise, process the resolver result. + Request* request = self->request_; + if (GPR_UNLIKELY(error != GRPC_ERROR_NONE)) { + if (self->tracer_enabled_) { + gpr_log(GPR_INFO, + "request_router=%p request=%p: resolver failed to return data", + request_router, request); + } + GRPC_CLOSURE_RUN(request->on_route_done_, GRPC_ERROR_REF(error)); + } else if (GPR_UNLIKELY(request_router->resolver_ == nullptr)) { + // Shutting down. + if (self->tracer_enabled_) { + gpr_log(GPR_INFO, "request_router=%p request=%p: resolver disconnected", + request_router, request); + } + GRPC_CLOSURE_RUN(request->on_route_done_, + GRPC_ERROR_CREATE_FROM_STATIC_STRING("Disconnected")); + } else if (GPR_UNLIKELY(request_router->lb_policy_ == nullptr)) { + // Transient resolver failure. + // If call has wait_for_ready=true, try again; otherwise, fail. + if (*request->pick_.initial_metadata_flags & + GRPC_INITIAL_METADATA_WAIT_FOR_READY) { + if (self->tracer_enabled_) { + gpr_log(GPR_INFO, + "request_router=%p request=%p: resolver returned but no LB " + "policy; wait_for_ready=true; trying again", + request_router, request); + } + // Re-add ourselves to the waiting list. + self->AddToWaitingList(); + // Return early so that we don't set finished_ to true below. + return; + } else { + if (self->tracer_enabled_) { + gpr_log(GPR_INFO, + "request_router=%p request=%p: resolver returned but no LB " + "policy; wait_for_ready=false; failing", + request_router, request); + } + GRPC_CLOSURE_RUN( + request->on_route_done_, + grpc_error_set_int( + GRPC_ERROR_CREATE_FROM_STATIC_STRING("Name resolution failure"), + GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_UNAVAILABLE)); + } + } else { + if (self->tracer_enabled_) { + gpr_log(GPR_INFO, + "request_router=%p request=%p: resolver returned, doing LB " + "pick", + request_router, request); + } + request->ProcessServiceConfigAndStartLbPickLocked(); + } + self->finished_ = true; + } + + // Invoked when the call is cancelled. + // Note: This runs under the client_channel combiner, but will NOT be + // holding the call combiner. + static void CancelLocked(void* arg, grpc_error* error) { + ResolverResultWaiter* self = static_cast<ResolverResultWaiter*>(arg); + RequestRouter* request_router = self->request_router_; + // If DoneLocked() has already run, delete ourselves without doing anything. + if (self->finished_) { + Delete(self); + return; + } + Request* request = self->request_; + // If we are being cancelled, immediately invoke on_route_done_ + // to propagate the error back to the caller. + if (error != GRPC_ERROR_NONE) { + if (self->tracer_enabled_) { + gpr_log(GPR_INFO, + "request_router=%p request=%p: cancelling call waiting for " + "name resolution", + request_router, request); + } + // Note: Although we are not in the call combiner here, we are + // basically stealing the call combiner from the pending pick, so + // it's safe to run on_route_done_ here -- we are essentially + // calling it here instead of calling it in DoneLocked(). + GRPC_CLOSURE_RUN(request->on_route_done_, + GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING( + "Pick cancelled", &error, 1)); + } + self->finished_ = true; + } + + RequestRouter* request_router_; + Request* request_; + const bool tracer_enabled_; + grpc_closure done_closure_; + grpc_closure cancel_closure_; + bool finished_ = false; +}; + +// +// RequestRouter::Request::AsyncPickCanceller +// + +// Handles the call combiner cancellation callback for an async LB pick. +class RequestRouter::Request::AsyncPickCanceller { + public: + explicit AsyncPickCanceller(Request* request) + : request_router_(request->request_router_), + request_(request), + tracer_enabled_(request_router_->tracer_->enabled()) { + GRPC_CALL_STACK_REF(request->owning_call_, "pick_callback_cancel"); + // Set cancellation closure, so that we abort if the call is cancelled. + GRPC_CLOSURE_INIT(&cancel_closure_, &CancelLocked, this, + grpc_combiner_scheduler(request_router_->combiner_)); + grpc_call_combiner_set_notify_on_cancel(request->call_combiner_, + &cancel_closure_); + } + + void MarkFinishedLocked() { + finished_ = true; + GRPC_CALL_STACK_UNREF(request_->owning_call_, "pick_callback_cancel"); + } + + private: + // Invoked when the call is cancelled. + // Note: This runs under the client_channel combiner, but will NOT be + // holding the call combiner. + static void CancelLocked(void* arg, grpc_error* error) { + AsyncPickCanceller* self = static_cast<AsyncPickCanceller*>(arg); + Request* request = self->request_; + RequestRouter* request_router = self->request_router_; + if (!self->finished_) { + // Note: request_router->lb_policy_ may have changed since we started our + // pick, in which case we will be cancelling the pick on a policy other + // than the one we started it on. However, this will just be a no-op. + if (error != GRPC_ERROR_NONE && request_router->lb_policy_ != nullptr) { + if (self->tracer_enabled_) { + gpr_log(GPR_INFO, + "request_router=%p request=%p: cancelling pick from LB " + "policy %p", + request_router, request, request_router->lb_policy_.get()); + } + request_router->lb_policy_->CancelPickLocked(&request->pick_, + GRPC_ERROR_REF(error)); + } + request->pick_canceller_ = nullptr; + GRPC_CALL_STACK_UNREF(request->owning_call_, "pick_callback_cancel"); + } + Delete(self); + } + + RequestRouter* request_router_; + Request* request_; + const bool tracer_enabled_; + grpc_closure cancel_closure_; + bool finished_ = false; +}; + +// +// RequestRouter::Request +// + +RequestRouter::Request::Request(grpc_call_stack* owning_call, + grpc_call_combiner* call_combiner, + grpc_polling_entity* pollent, + grpc_metadata_batch* send_initial_metadata, + uint32_t* send_initial_metadata_flags, + ApplyServiceConfigCallback apply_service_config, + void* apply_service_config_user_data, + grpc_closure* on_route_done) + : owning_call_(owning_call), + call_combiner_(call_combiner), + pollent_(pollent), + apply_service_config_(apply_service_config), + apply_service_config_user_data_(apply_service_config_user_data), + on_route_done_(on_route_done) { + pick_.initial_metadata = send_initial_metadata; + pick_.initial_metadata_flags = send_initial_metadata_flags; +} + +RequestRouter::Request::~Request() { + if (pick_.connected_subchannel != nullptr) { + pick_.connected_subchannel.reset(); + } + for (size_t i = 0; i < GRPC_CONTEXT_COUNT; ++i) { + if (pick_.subchannel_call_context[i].destroy != nullptr) { + pick_.subchannel_call_context[i].destroy( + pick_.subchannel_call_context[i].value); + } + } +} + +// Invoked once resolver results are available. +void RequestRouter::Request::ProcessServiceConfigAndStartLbPickLocked() { + // Get service config data if needed. + if (!apply_service_config_(apply_service_config_user_data_)) return; + // Start LB pick. + StartLbPickLocked(); +} + +void RequestRouter::Request::MaybeAddCallToInterestedPartiesLocked() { + if (!pollent_added_to_interested_parties_) { + pollent_added_to_interested_parties_ = true; + grpc_polling_entity_add_to_pollset_set( + pollent_, request_router_->interested_parties_); + } +} + +void RequestRouter::Request::MaybeRemoveCallFromInterestedPartiesLocked() { + if (pollent_added_to_interested_parties_) { + pollent_added_to_interested_parties_ = false; + grpc_polling_entity_del_from_pollset_set( + pollent_, request_router_->interested_parties_); + } +} + +// Starts a pick on the LB policy. +void RequestRouter::Request::StartLbPickLocked() { + if (request_router_->tracer_->enabled()) { + gpr_log(GPR_INFO, + "request_router=%p request=%p: starting pick on lb_policy=%p", + request_router_, this, request_router_->lb_policy_.get()); + } + GRPC_CLOSURE_INIT(&on_pick_done_, &LbPickDoneLocked, this, + grpc_combiner_scheduler(request_router_->combiner_)); + pick_.on_complete = &on_pick_done_; + GRPC_CALL_STACK_REF(owning_call_, "pick_callback"); + grpc_error* error = GRPC_ERROR_NONE; + const bool pick_done = + request_router_->lb_policy_->PickLocked(&pick_, &error); + if (pick_done) { + // Pick completed synchronously. + if (request_router_->tracer_->enabled()) { + gpr_log(GPR_INFO, + "request_router=%p request=%p: pick completed synchronously", + request_router_, this); + } + GRPC_CLOSURE_RUN(on_route_done_, error); + GRPC_CALL_STACK_UNREF(owning_call_, "pick_callback"); + } else { + // Pick will be returned asynchronously. + // Add the request's polling entity to the request_router's + // interested_parties, so that the I/O of the LB policy can be done + // under it. It will be removed in LbPickDoneLocked(). + MaybeAddCallToInterestedPartiesLocked(); + // Request notification on call cancellation. + // We allocate a separate object to track cancellation, since the + // cancellation closure might still be pending when we need to reuse + // the memory in which this Request object is stored for a subsequent + // retry attempt. + pick_canceller_ = New<AsyncPickCanceller>(this); + } +} + +// Callback invoked by LoadBalancingPolicy::PickLocked() for async picks. +// Unrefs the LB policy and invokes on_route_done_. +void RequestRouter::Request::LbPickDoneLocked(void* arg, grpc_error* error) { + Request* self = static_cast<Request*>(arg); + RequestRouter* request_router = self->request_router_; + if (request_router->tracer_->enabled()) { + gpr_log(GPR_INFO, + "request_router=%p request=%p: pick completed asynchronously", + request_router, self); + } + self->MaybeRemoveCallFromInterestedPartiesLocked(); + if (self->pick_canceller_ != nullptr) { + self->pick_canceller_->MarkFinishedLocked(); + } + GRPC_CLOSURE_RUN(self->on_route_done_, GRPC_ERROR_REF(error)); + GRPC_CALL_STACK_UNREF(self->owning_call_, "pick_callback"); +} + +// +// RequestRouter::LbConnectivityWatcher +// + +class RequestRouter::LbConnectivityWatcher { + public: + LbConnectivityWatcher(RequestRouter* request_router, + grpc_connectivity_state state, + LoadBalancingPolicy* lb_policy, + grpc_channel_stack* owning_stack, + grpc_combiner* combiner) + : request_router_(request_router), + state_(state), + lb_policy_(lb_policy), + owning_stack_(owning_stack) { + GRPC_CHANNEL_STACK_REF(owning_stack_, "LbConnectivityWatcher"); + GRPC_CLOSURE_INIT(&on_changed_, &OnLbPolicyStateChangedLocked, this, + grpc_combiner_scheduler(combiner)); + lb_policy_->NotifyOnStateChangeLocked(&state_, &on_changed_); + } + + ~LbConnectivityWatcher() { + GRPC_CHANNEL_STACK_UNREF(owning_stack_, "LbConnectivityWatcher"); + } + + private: + static void OnLbPolicyStateChangedLocked(void* arg, grpc_error* error) { + LbConnectivityWatcher* self = static_cast<LbConnectivityWatcher*>(arg); + // If the notification is not for the current policy, we're stale, + // so delete ourselves. + if (self->lb_policy_ != self->request_router_->lb_policy_.get()) { + Delete(self); + return; + } + // Otherwise, process notification. + if (self->request_router_->tracer_->enabled()) { + gpr_log(GPR_INFO, "request_router=%p: lb_policy=%p state changed to %s", + self->request_router_, self->lb_policy_, + grpc_connectivity_state_name(self->state_)); + } + self->request_router_->SetConnectivityStateLocked( + self->state_, GRPC_ERROR_REF(error), "lb_changed"); + // If shutting down, terminate watch. + if (self->state_ == GRPC_CHANNEL_SHUTDOWN) { + Delete(self); + return; + } + // Renew watch. + self->lb_policy_->NotifyOnStateChangeLocked(&self->state_, + &self->on_changed_); + } + + RequestRouter* request_router_; + grpc_connectivity_state state_; + // LB policy address. No ref held, so not safe to dereference unless + // it happens to match request_router->lb_policy_. + LoadBalancingPolicy* lb_policy_; + grpc_channel_stack* owning_stack_; + grpc_closure on_changed_; +}; + +// +// RequestRounter::ReresolutionRequestHandler +// + +class RequestRouter::ReresolutionRequestHandler { + public: + ReresolutionRequestHandler(RequestRouter* request_router, + LoadBalancingPolicy* lb_policy, + grpc_channel_stack* owning_stack, + grpc_combiner* combiner) + : request_router_(request_router), + lb_policy_(lb_policy), + owning_stack_(owning_stack) { + GRPC_CHANNEL_STACK_REF(owning_stack_, "ReresolutionRequestHandler"); + GRPC_CLOSURE_INIT(&closure_, &OnRequestReresolutionLocked, this, + grpc_combiner_scheduler(combiner)); + lb_policy_->SetReresolutionClosureLocked(&closure_); + } + + private: + static void OnRequestReresolutionLocked(void* arg, grpc_error* error) { + ReresolutionRequestHandler* self = + static_cast<ReresolutionRequestHandler*>(arg); + RequestRouter* request_router = self->request_router_; + // If this invocation is for a stale LB policy, treat it as an LB shutdown + // signal. + if (self->lb_policy_ != request_router->lb_policy_.get() || + error != GRPC_ERROR_NONE || request_router->resolver_ == nullptr) { + GRPC_CHANNEL_STACK_UNREF(request_router->owning_stack_, + "ReresolutionRequestHandler"); + Delete(self); + return; + } + if (request_router->tracer_->enabled()) { + gpr_log(GPR_INFO, "request_router=%p: started name re-resolving", + request_router); + } + request_router->resolver_->RequestReresolutionLocked(); + // Give back the closure to the LB policy. + self->lb_policy_->SetReresolutionClosureLocked(&self->closure_); + } + + RequestRouter* request_router_; + // LB policy address. No ref held, so not safe to dereference unless + // it happens to match request_router->lb_policy_. + LoadBalancingPolicy* lb_policy_; + grpc_channel_stack* owning_stack_; + grpc_closure closure_; +}; + +// +// RequestRouter +// + +RequestRouter::RequestRouter( + grpc_channel_stack* owning_stack, grpc_combiner* combiner, + grpc_client_channel_factory* client_channel_factory, + grpc_pollset_set* interested_parties, TraceFlag* tracer, + ProcessResolverResultCallback process_resolver_result, + void* process_resolver_result_user_data, const char* target_uri, + const grpc_channel_args* args, grpc_error** error) + : owning_stack_(owning_stack), + combiner_(combiner), + client_channel_factory_(client_channel_factory), + interested_parties_(interested_parties), + tracer_(tracer), + process_resolver_result_(process_resolver_result), + process_resolver_result_user_data_(process_resolver_result_user_data) { + GRPC_CLOSURE_INIT(&on_resolver_result_changed_, + &RequestRouter::OnResolverResultChangedLocked, this, + grpc_combiner_scheduler(combiner)); + grpc_connectivity_state_init(&state_tracker_, GRPC_CHANNEL_IDLE, + "request_router"); + grpc_channel_args* new_args = nullptr; + if (process_resolver_result == nullptr) { + grpc_arg arg = grpc_channel_arg_integer_create( + const_cast<char*>(GRPC_ARG_SERVICE_CONFIG_DISABLE_RESOLUTION), 0); + new_args = grpc_channel_args_copy_and_add(args, &arg, 1); + } + resolver_ = ResolverRegistry::CreateResolver( + target_uri, (new_args == nullptr ? args : new_args), interested_parties_, + combiner_); + grpc_channel_args_destroy(new_args); + if (resolver_ == nullptr) { + *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("resolver creation failed"); + } +} + +RequestRouter::~RequestRouter() { + if (resolver_ != nullptr) { + // The only way we can get here is if we never started resolving, + // because we take a ref to the channel stack when we start + // resolving and do not release it until the resolver callback is + // invoked after the resolver shuts down. + resolver_.reset(); + } + if (lb_policy_ != nullptr) { + grpc_pollset_set_del_pollset_set(lb_policy_->interested_parties(), + interested_parties_); + lb_policy_.reset(); + } + if (client_channel_factory_ != nullptr) { + grpc_client_channel_factory_unref(client_channel_factory_); + } + grpc_connectivity_state_destroy(&state_tracker_); +} + +namespace { + +const char* GetChannelConnectivityStateChangeString( + grpc_connectivity_state state) { + switch (state) { + case GRPC_CHANNEL_IDLE: + return "Channel state change to IDLE"; + case GRPC_CHANNEL_CONNECTING: + return "Channel state change to CONNECTING"; + case GRPC_CHANNEL_READY: + return "Channel state change to READY"; + case GRPC_CHANNEL_TRANSIENT_FAILURE: + return "Channel state change to TRANSIENT_FAILURE"; + case GRPC_CHANNEL_SHUTDOWN: + return "Channel state change to SHUTDOWN"; + } + GPR_UNREACHABLE_CODE(return "UNKNOWN"); +} + +} // namespace + +void RequestRouter::SetConnectivityStateLocked(grpc_connectivity_state state, + grpc_error* error, + const char* reason) { + if (lb_policy_ != nullptr) { + if (state == GRPC_CHANNEL_TRANSIENT_FAILURE) { + // Cancel picks with wait_for_ready=false. + lb_policy_->CancelMatchingPicksLocked( + /* mask= */ GRPC_INITIAL_METADATA_WAIT_FOR_READY, + /* check= */ 0, GRPC_ERROR_REF(error)); + } else if (state == GRPC_CHANNEL_SHUTDOWN) { + // Cancel all picks. + lb_policy_->CancelMatchingPicksLocked(/* mask= */ 0, /* check= */ 0, + GRPC_ERROR_REF(error)); + } + } + if (tracer_->enabled()) { + gpr_log(GPR_INFO, "request_router=%p: setting connectivity state to %s", + this, grpc_connectivity_state_name(state)); + } + if (channelz_node_ != nullptr) { + channelz_node_->AddTraceEvent( + channelz::ChannelTrace::Severity::Info, + grpc_slice_from_static_string( + GetChannelConnectivityStateChangeString(state))); + } + grpc_connectivity_state_set(&state_tracker_, state, error, reason); +} + +void RequestRouter::StartResolvingLocked() { + if (tracer_->enabled()) { + gpr_log(GPR_INFO, "request_router=%p: starting name resolution", this); + } + GPR_ASSERT(!started_resolving_); + started_resolving_ = true; + GRPC_CHANNEL_STACK_REF(owning_stack_, "resolver"); + resolver_->NextLocked(&resolver_result_, &on_resolver_result_changed_); +} + +// Invoked from the resolver NextLocked() callback when the resolver +// is shutting down. +void RequestRouter::OnResolverShutdownLocked(grpc_error* error) { + if (tracer_->enabled()) { + gpr_log(GPR_INFO, "request_router=%p: shutting down", this); + } + if (lb_policy_ != nullptr) { + if (tracer_->enabled()) { + gpr_log(GPR_INFO, "request_router=%p: shutting down lb_policy=%p", this, + lb_policy_.get()); + } + grpc_pollset_set_del_pollset_set(lb_policy_->interested_parties(), + interested_parties_); + lb_policy_.reset(); + } + if (resolver_ != nullptr) { + // This should never happen; it can only be triggered by a resolver + // implementation spotaneously deciding to report shutdown without + // being orphaned. This code is included just to be defensive. + if (tracer_->enabled()) { + gpr_log(GPR_INFO, + "request_router=%p: spontaneous shutdown from resolver %p", this, + resolver_.get()); + } + resolver_.reset(); + SetConnectivityStateLocked(GRPC_CHANNEL_SHUTDOWN, + GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING( + "Resolver spontaneous shutdown", &error, 1), + "resolver_spontaneous_shutdown"); + } + grpc_closure_list_fail_all(&waiting_for_resolver_result_closures_, + GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING( + "Channel disconnected", &error, 1)); + GRPC_CLOSURE_LIST_SCHED(&waiting_for_resolver_result_closures_); + GRPC_CHANNEL_STACK_UNREF(owning_stack_, "resolver"); + grpc_channel_args_destroy(resolver_result_); + resolver_result_ = nullptr; + GRPC_ERROR_UNREF(error); +} + +// Creates a new LB policy, replacing any previous one. +// If the new policy is created successfully, sets *connectivity_state and +// *connectivity_error to its initial connectivity state; otherwise, +// leaves them unchanged. +void RequestRouter::CreateNewLbPolicyLocked( + const char* lb_policy_name, grpc_json* lb_config, + grpc_connectivity_state* connectivity_state, + grpc_error** connectivity_error, TraceStringVector* trace_strings) { + LoadBalancingPolicy::Args lb_policy_args; + lb_policy_args.combiner = combiner_; + lb_policy_args.client_channel_factory = client_channel_factory_; + lb_policy_args.args = resolver_result_; + lb_policy_args.lb_config = lb_config; + OrphanablePtr<LoadBalancingPolicy> new_lb_policy = + LoadBalancingPolicyRegistry::CreateLoadBalancingPolicy(lb_policy_name, + lb_policy_args); + if (GPR_UNLIKELY(new_lb_policy == nullptr)) { + gpr_log(GPR_ERROR, "could not create LB policy \"%s\"", lb_policy_name); + if (channelz_node_ != nullptr) { + char* str; + gpr_asprintf(&str, "Could not create LB policy \'%s\'", lb_policy_name); + trace_strings->push_back(str); + } + } else { + if (tracer_->enabled()) { + gpr_log(GPR_INFO, "request_router=%p: created new LB policy \"%s\" (%p)", + this, lb_policy_name, new_lb_policy.get()); + } + if (channelz_node_ != nullptr) { + char* str; + gpr_asprintf(&str, "Created new LB policy \'%s\'", lb_policy_name); + trace_strings->push_back(str); + } + // Swap out the LB policy and update the fds in interested_parties_. + if (lb_policy_ != nullptr) { + if (tracer_->enabled()) { + gpr_log(GPR_INFO, "request_router=%p: shutting down lb_policy=%p", this, + lb_policy_.get()); + } + grpc_pollset_set_del_pollset_set(lb_policy_->interested_parties(), + interested_parties_); + lb_policy_->HandOffPendingPicksLocked(new_lb_policy.get()); + } + lb_policy_ = std::move(new_lb_policy); + grpc_pollset_set_add_pollset_set(lb_policy_->interested_parties(), + interested_parties_); + // Create re-resolution request handler for the new LB policy. It + // will delete itself when no longer needed. + New<ReresolutionRequestHandler>(this, lb_policy_.get(), owning_stack_, + combiner_); + // Get the new LB policy's initial connectivity state and start a + // connectivity watch. + GRPC_ERROR_UNREF(*connectivity_error); + *connectivity_state = + lb_policy_->CheckConnectivityLocked(connectivity_error); + if (exit_idle_when_lb_policy_arrives_) { + lb_policy_->ExitIdleLocked(); + exit_idle_when_lb_policy_arrives_ = false; + } + // Create new watcher. It will delete itself when done. + New<LbConnectivityWatcher>(this, *connectivity_state, lb_policy_.get(), + owning_stack_, combiner_); + } +} + +void RequestRouter::MaybeAddTraceMessagesForAddressChangesLocked( + TraceStringVector* trace_strings) { + const ServerAddressList* addresses = + FindServerAddressListChannelArg(resolver_result_); + const bool resolution_contains_addresses = + addresses != nullptr && addresses->size() > 0; + if (!resolution_contains_addresses && + previous_resolution_contained_addresses_) { + trace_strings->push_back(gpr_strdup("Address list became empty")); + } else if (resolution_contains_addresses && + !previous_resolution_contained_addresses_) { + trace_strings->push_back(gpr_strdup("Address list became non-empty")); + } + previous_resolution_contained_addresses_ = resolution_contains_addresses; +} + +void RequestRouter::ConcatenateAndAddChannelTraceLocked( + TraceStringVector* trace_strings) const { + if (!trace_strings->empty()) { + gpr_strvec v; + gpr_strvec_init(&v); + gpr_strvec_add(&v, gpr_strdup("Resolution event: ")); + bool is_first = 1; + for (size_t i = 0; i < trace_strings->size(); ++i) { + if (!is_first) gpr_strvec_add(&v, gpr_strdup(", ")); + is_first = false; + gpr_strvec_add(&v, (*trace_strings)[i]); + } + char* flat; + size_t flat_len = 0; + flat = gpr_strvec_flatten(&v, &flat_len); + channelz_node_->AddTraceEvent( + grpc_core::channelz::ChannelTrace::Severity::Info, + grpc_slice_new(flat, flat_len, gpr_free)); + gpr_strvec_destroy(&v); + } +} + +// Callback invoked when a resolver result is available. +void RequestRouter::OnResolverResultChangedLocked(void* arg, + grpc_error* error) { + RequestRouter* self = static_cast<RequestRouter*>(arg); + if (self->tracer_->enabled()) { + const char* disposition = + self->resolver_result_ != nullptr + ? "" + : (error == GRPC_ERROR_NONE ? " (transient error)" + : " (resolver shutdown)"); + gpr_log(GPR_INFO, + "request_router=%p: got resolver result: resolver_result=%p " + "error=%s%s", + self, self->resolver_result_, grpc_error_string(error), + disposition); + } + // Handle shutdown. + if (error != GRPC_ERROR_NONE || self->resolver_ == nullptr) { + self->OnResolverShutdownLocked(GRPC_ERROR_REF(error)); + return; + } + // Data used to set the channel's connectivity state. + bool set_connectivity_state = true; + // We only want to trace the address resolution in the follow cases: + // (a) Address resolution resulted in service config change. + // (b) Address resolution that causes number of backends to go from + // zero to non-zero. + // (c) Address resolution that causes number of backends to go from + // non-zero to zero. + // (d) Address resolution that causes a new LB policy to be created. + // + // we track a list of strings to eventually be concatenated and traced. + TraceStringVector trace_strings; + grpc_connectivity_state connectivity_state = GRPC_CHANNEL_TRANSIENT_FAILURE; + grpc_error* connectivity_error = + GRPC_ERROR_CREATE_FROM_STATIC_STRING("No load balancing policy"); + // resolver_result_ will be null in the case of a transient + // resolution error. In that case, we don't have any new result to + // process, which means that we keep using the previous result (if any). + if (self->resolver_result_ == nullptr) { + if (self->tracer_->enabled()) { + gpr_log(GPR_INFO, "request_router=%p: resolver transient failure", self); + } + // Don't override connectivity state if we already have an LB policy. + if (self->lb_policy_ != nullptr) set_connectivity_state = false; + } else { + // Parse the resolver result. + const char* lb_policy_name = nullptr; + grpc_json* lb_policy_config = nullptr; + const bool service_config_changed = self->process_resolver_result_( + self->process_resolver_result_user_data_, *self->resolver_result_, + &lb_policy_name, &lb_policy_config); + GPR_ASSERT(lb_policy_name != nullptr); + // Check to see if we're already using the right LB policy. + const bool lb_policy_name_changed = + self->lb_policy_ == nullptr || + strcmp(self->lb_policy_->name(), lb_policy_name) != 0; + if (self->lb_policy_ != nullptr && !lb_policy_name_changed) { + // Continue using the same LB policy. Update with new addresses. + if (self->tracer_->enabled()) { + gpr_log(GPR_INFO, + "request_router=%p: updating existing LB policy \"%s\" (%p)", + self, lb_policy_name, self->lb_policy_.get()); + } + self->lb_policy_->UpdateLocked(*self->resolver_result_, lb_policy_config); + // No need to set the channel's connectivity state; the existing + // watch on the LB policy will take care of that. + set_connectivity_state = false; + } else { + // Instantiate new LB policy. + self->CreateNewLbPolicyLocked(lb_policy_name, lb_policy_config, + &connectivity_state, &connectivity_error, + &trace_strings); + } + // Add channel trace event. + if (self->channelz_node_ != nullptr) { + if (service_config_changed) { + // TODO(ncteisen): might be worth somehow including a snippet of the + // config in the trace, at the risk of bloating the trace logs. + trace_strings.push_back(gpr_strdup("Service config changed")); + } + self->MaybeAddTraceMessagesForAddressChangesLocked(&trace_strings); + self->ConcatenateAndAddChannelTraceLocked(&trace_strings); + } + // Clean up. + grpc_channel_args_destroy(self->resolver_result_); + self->resolver_result_ = nullptr; + } + // Set the channel's connectivity state if needed. + if (set_connectivity_state) { + self->SetConnectivityStateLocked(connectivity_state, connectivity_error, + "resolver_result"); + } else { + GRPC_ERROR_UNREF(connectivity_error); + } + // Invoke closures that were waiting for results and renew the watch. + GRPC_CLOSURE_LIST_SCHED(&self->waiting_for_resolver_result_closures_); + self->resolver_->NextLocked(&self->resolver_result_, + &self->on_resolver_result_changed_); +} + +void RequestRouter::RouteCallLocked(Request* request) { + GPR_ASSERT(request->pick_.connected_subchannel == nullptr); + request->request_router_ = this; + if (lb_policy_ != nullptr) { + // We already have resolver results, so process the service config + // and start an LB pick. + request->ProcessServiceConfigAndStartLbPickLocked(); + } else if (resolver_ == nullptr) { + GRPC_CLOSURE_RUN(request->on_route_done_, + GRPC_ERROR_CREATE_FROM_STATIC_STRING("Disconnected")); + } else { + // We do not yet have an LB policy, so wait for a resolver result. + if (!started_resolving_) { + StartResolvingLocked(); + } + // Create a new waiter, which will delete itself when done. + New<Request::ResolverResultWaiter>(request); + // Add the request's polling entity to the request_router's + // interested_parties, so that the I/O of the resolver can be done + // under it. It will be removed in LbPickDoneLocked(). + request->MaybeAddCallToInterestedPartiesLocked(); + } +} + +void RequestRouter::ShutdownLocked(grpc_error* error) { + if (resolver_ != nullptr) { + SetConnectivityStateLocked(GRPC_CHANNEL_SHUTDOWN, GRPC_ERROR_REF(error), + "disconnect"); + resolver_.reset(); + if (!started_resolving_) { + grpc_closure_list_fail_all(&waiting_for_resolver_result_closures_, + GRPC_ERROR_REF(error)); + GRPC_CLOSURE_LIST_SCHED(&waiting_for_resolver_result_closures_); + } + if (lb_policy_ != nullptr) { + grpc_pollset_set_del_pollset_set(lb_policy_->interested_parties(), + interested_parties_); + lb_policy_.reset(); + } + } + GRPC_ERROR_UNREF(error); +} + +grpc_connectivity_state RequestRouter::GetConnectivityState() { + return grpc_connectivity_state_check(&state_tracker_); +} + +void RequestRouter::NotifyOnConnectivityStateChange( + grpc_connectivity_state* state, grpc_closure* closure) { + grpc_connectivity_state_notify_on_state_change(&state_tracker_, state, + closure); +} + +void RequestRouter::ExitIdleLocked() { + if (lb_policy_ != nullptr) { + lb_policy_->ExitIdleLocked(); + } else { + exit_idle_when_lb_policy_arrives_ = true; + if (!started_resolving_ && resolver_ != nullptr) { + StartResolvingLocked(); + } + } +} + +void RequestRouter::ResetConnectionBackoffLocked() { + if (resolver_ != nullptr) { + resolver_->ResetBackoffLocked(); + resolver_->RequestReresolutionLocked(); + } + if (lb_policy_ != nullptr) { + lb_policy_->ResetBackoffLocked(); + } +} + +} // namespace grpc_core |