Merge pull request #24806 from markdroth/client_channel_split0
Eliminate ResolvingLoadBalancingPolicy.reviewable/pr24834/r4^2
Mark D. Roth
4 years ago
committed by
GitHub
commit
d6298ed3dc
19 changed files with 347 additions and 734 deletions
@ -1,355 +0,0 @@ |
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/*
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* |
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* Copyright 2015 gRPC authors. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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* |
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*/ |
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#include <grpc/support/port_platform.h> |
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#include "src/core/ext/filters/client_channel/resolving_lb_policy.h" |
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#include <inttypes.h> |
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#include <limits.h> |
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#include <stdbool.h> |
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#include <stdio.h> |
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#include <string.h> |
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#include "absl/strings/str_cat.h" |
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#include "absl/strings/str_join.h" |
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#include <grpc/support/alloc.h> |
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#include <grpc/support/log.h> |
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#include <grpc/support/string_util.h> |
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#include <grpc/support/sync.h> |
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#include "src/core/ext/filters/client_channel/backup_poller.h" |
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#include "src/core/ext/filters/client_channel/http_connect_handshaker.h" |
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#include "src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h" |
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#include "src/core/ext/filters/client_channel/lb_policy_registry.h" |
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#include "src/core/ext/filters/client_channel/proxy_mapper_registry.h" |
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#include "src/core/ext/filters/client_channel/resolver_registry.h" |
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#include "src/core/ext/filters/client_channel/retry_throttle.h" |
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#include "src/core/ext/filters/client_channel/server_address.h" |
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#include "src/core/ext/filters/client_channel/service_config.h" |
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#include "src/core/ext/filters/client_channel/subchannel.h" |
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#include "src/core/ext/filters/deadline/deadline_filter.h" |
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#include "src/core/lib/backoff/backoff.h" |
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#include "src/core/lib/channel/channel_args.h" |
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#include "src/core/lib/channel/connected_channel.h" |
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#include "src/core/lib/channel/status_util.h" |
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#include "src/core/lib/gpr/string.h" |
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#include "src/core/lib/gprpp/manual_constructor.h" |
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#include "src/core/lib/gprpp/sync.h" |
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#include "src/core/lib/iomgr/iomgr.h" |
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#include "src/core/lib/iomgr/polling_entity.h" |
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#include "src/core/lib/profiling/timers.h" |
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#include "src/core/lib/slice/slice_internal.h" |
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#include "src/core/lib/slice/slice_string_helpers.h" |
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#include "src/core/lib/surface/channel.h" |
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#include "src/core/lib/transport/connectivity_state.h" |
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#include "src/core/lib/transport/error_utils.h" |
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#include "src/core/lib/transport/metadata.h" |
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#include "src/core/lib/transport/metadata_batch.h" |
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#include "src/core/lib/transport/static_metadata.h" |
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#include "src/core/lib/transport/status_metadata.h" |
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namespace grpc_core { |
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//
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// ResolvingLoadBalancingPolicy::ResolverResultHandler
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//
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class ResolvingLoadBalancingPolicy::ResolverResultHandler |
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: public Resolver::ResultHandler { |
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public: |
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explicit ResolverResultHandler( |
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RefCountedPtr<ResolvingLoadBalancingPolicy> parent) |
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: parent_(std::move(parent)) {} |
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~ResolverResultHandler() override { |
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if (GRPC_TRACE_FLAG_ENABLED(*(parent_->tracer_))) { |
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gpr_log(GPR_INFO, "resolving_lb=%p: resolver shutdown complete", |
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parent_.get()); |
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} |
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} |
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void ReturnResult(Resolver::Result result) override { |
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parent_->OnResolverResultChangedLocked(std::move(result)); |
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} |
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void ReturnError(grpc_error* error) override { |
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parent_->OnResolverError(error); |
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} |
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private: |
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RefCountedPtr<ResolvingLoadBalancingPolicy> parent_; |
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}; |
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//
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// ResolvingLoadBalancingPolicy::ResolvingControlHelper
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//
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class ResolvingLoadBalancingPolicy::ResolvingControlHelper |
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: public LoadBalancingPolicy::ChannelControlHelper { |
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public: |
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explicit ResolvingControlHelper( |
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RefCountedPtr<ResolvingLoadBalancingPolicy> parent) |
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: parent_(std::move(parent)) {} |
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RefCountedPtr<SubchannelInterface> CreateSubchannel( |
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ServerAddress address, const grpc_channel_args& args) override { |
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if (parent_->resolver_ == nullptr) return nullptr; // Shutting down.
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return parent_->channel_control_helper()->CreateSubchannel( |
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std::move(address), args); |
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} |
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void UpdateState(grpc_connectivity_state state, const absl::Status& status, |
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std::unique_ptr<SubchannelPicker> picker) override { |
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if (parent_->resolver_ == nullptr) return; // Shutting down.
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parent_->channel_control_helper()->UpdateState(state, status, |
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std::move(picker)); |
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} |
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void RequestReresolution() override { |
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if (parent_->resolver_ == nullptr) return; // Shutting down.
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if (GRPC_TRACE_FLAG_ENABLED(*(parent_->tracer_))) { |
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gpr_log(GPR_INFO, "resolving_lb=%p: started name re-resolving", |
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parent_.get()); |
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} |
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parent_->resolver_->RequestReresolutionLocked(); |
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} |
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void AddTraceEvent(TraceSeverity severity, |
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absl::string_view message) override { |
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if (parent_->resolver_ == nullptr) return; // Shutting down.
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parent_->channel_control_helper()->AddTraceEvent(severity, message); |
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} |
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private: |
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RefCountedPtr<ResolvingLoadBalancingPolicy> parent_; |
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}; |
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//
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// ResolvingLoadBalancingPolicy
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//
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ResolvingLoadBalancingPolicy::ResolvingLoadBalancingPolicy( |
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Args args, TraceFlag* tracer, grpc_core::UniquePtr<char> target_uri, |
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ChannelConfigHelper* helper) |
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: LoadBalancingPolicy(std::move(args)), |
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tracer_(tracer), |
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target_uri_(std::move(target_uri)), |
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helper_(helper) { |
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GPR_ASSERT(helper_ != nullptr); |
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resolver_ = ResolverRegistry::CreateResolver( |
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target_uri_.get(), args.args, interested_parties(), work_serializer(), |
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absl::make_unique<ResolverResultHandler>(Ref())); |
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// Since the validity of args has been checked when create the channel,
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// CreateResolver() must return a non-null result.
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GPR_ASSERT(resolver_ != nullptr); |
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if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) { |
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gpr_log(GPR_INFO, "resolving_lb=%p: starting name resolution", this); |
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} |
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channel_control_helper()->UpdateState(GRPC_CHANNEL_CONNECTING, absl::Status(), |
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absl::make_unique<QueuePicker>(Ref())); |
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resolver_->StartLocked(); |
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} |
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ResolvingLoadBalancingPolicy::~ResolvingLoadBalancingPolicy() { |
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GPR_ASSERT(resolver_ == nullptr); |
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GPR_ASSERT(lb_policy_ == nullptr); |
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} |
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void ResolvingLoadBalancingPolicy::ShutdownLocked() { |
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if (resolver_ != nullptr) { |
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if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) { |
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gpr_log(GPR_INFO, "resolving_lb=%p: shutting down resolver=%p", this, |
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resolver_.get()); |
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} |
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resolver_.reset(); |
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if (lb_policy_ != nullptr) { |
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if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) { |
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gpr_log(GPR_INFO, "resolving_lb=%p: shutting down lb_policy=%p", this, |
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lb_policy_.get()); |
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} |
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grpc_pollset_set_del_pollset_set(lb_policy_->interested_parties(), |
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interested_parties()); |
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lb_policy_.reset(); |
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} |
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} |
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} |
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void ResolvingLoadBalancingPolicy::ExitIdleLocked() { |
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if (lb_policy_ != nullptr) lb_policy_->ExitIdleLocked(); |
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} |
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void ResolvingLoadBalancingPolicy::ResetBackoffLocked() { |
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if (resolver_ != nullptr) { |
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resolver_->ResetBackoffLocked(); |
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resolver_->RequestReresolutionLocked(); |
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} |
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if (lb_policy_ != nullptr) lb_policy_->ResetBackoffLocked(); |
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} |
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void ResolvingLoadBalancingPolicy::OnResolverError(grpc_error* error) { |
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if (resolver_ == nullptr) { |
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GRPC_ERROR_UNREF(error); |
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return; |
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} |
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if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) { |
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gpr_log(GPR_INFO, "resolving_lb=%p: resolver transient failure: %s", this, |
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grpc_error_string(error)); |
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} |
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// If we already have an LB policy from a previous resolution
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// result, then we continue to let it set the connectivity state.
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// Otherwise, we go into TRANSIENT_FAILURE.
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if (lb_policy_ == nullptr) { |
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grpc_error* state_error = GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING( |
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"Resolver transient failure", &error, 1); |
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helper_->ResolverTransientFailure(GRPC_ERROR_REF(state_error)); |
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channel_control_helper()->UpdateState( |
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GRPC_CHANNEL_TRANSIENT_FAILURE, grpc_error_to_absl_status(state_error), |
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absl::make_unique<TransientFailurePicker>(state_error)); |
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} |
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GRPC_ERROR_UNREF(error); |
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} |
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void ResolvingLoadBalancingPolicy::CreateOrUpdateLbPolicyLocked( |
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RefCountedPtr<LoadBalancingPolicy::Config> lb_policy_config, |
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Resolver::Result result) { |
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// Construct update.
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UpdateArgs update_args; |
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update_args.addresses = std::move(result.addresses); |
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update_args.config = std::move(lb_policy_config); |
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// Remove the config selector from channel args so that we're not holding
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// unnecessary refs that cause it to be destroyed somewhere other than in the
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// WorkSerializer.
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const char* arg_name = GRPC_ARG_CONFIG_SELECTOR; |
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update_args.args = |
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grpc_channel_args_copy_and_remove(result.args, &arg_name, 1); |
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// Create policy if needed.
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if (lb_policy_ == nullptr) { |
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lb_policy_ = CreateLbPolicyLocked(*update_args.args); |
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} |
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// Update the policy.
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if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) { |
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gpr_log(GPR_INFO, "resolving_lb=%p: Updating child policy %p", this, |
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lb_policy_.get()); |
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} |
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lb_policy_->UpdateLocked(std::move(update_args)); |
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} |
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// Creates a new LB policy.
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OrphanablePtr<LoadBalancingPolicy> |
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ResolvingLoadBalancingPolicy::CreateLbPolicyLocked( |
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const grpc_channel_args& args) { |
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LoadBalancingPolicy::Args lb_policy_args; |
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lb_policy_args.work_serializer = work_serializer(); |
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lb_policy_args.channel_control_helper = |
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absl::make_unique<ResolvingControlHelper>(Ref()); |
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lb_policy_args.args = &args; |
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OrphanablePtr<LoadBalancingPolicy> lb_policy = |
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MakeOrphanable<ChildPolicyHandler>(std::move(lb_policy_args), tracer_); |
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if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) { |
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gpr_log(GPR_INFO, "resolving_lb=%p: created new LB policy %p", this, |
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lb_policy.get()); |
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} |
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grpc_pollset_set_add_pollset_set(lb_policy->interested_parties(), |
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interested_parties()); |
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return lb_policy; |
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} |
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void ResolvingLoadBalancingPolicy::MaybeAddTraceMessagesForAddressChangesLocked( |
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bool resolution_contains_addresses, TraceStringVector* trace_strings) { |
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if (!resolution_contains_addresses && |
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previous_resolution_contained_addresses_) { |
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trace_strings->push_back("Address list became empty"); |
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} else if (resolution_contains_addresses && |
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!previous_resolution_contained_addresses_) { |
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trace_strings->push_back("Address list became non-empty"); |
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} |
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previous_resolution_contained_addresses_ = resolution_contains_addresses; |
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} |
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void ResolvingLoadBalancingPolicy::ConcatenateAndAddChannelTraceLocked( |
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const TraceStringVector& trace_strings) const { |
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if (!trace_strings.empty()) { |
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std::string message = |
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absl::StrCat("Resolution event: ", absl::StrJoin(trace_strings, ", ")); |
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channel_control_helper()->AddTraceEvent(ChannelControlHelper::TRACE_INFO, |
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message); |
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} |
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} |
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void ResolvingLoadBalancingPolicy::OnResolverResultChangedLocked( |
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Resolver::Result result) { |
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// Handle race conditions.
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if (resolver_ == nullptr) return; |
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if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) { |
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gpr_log(GPR_INFO, "resolving_lb=%p: got resolver result", this); |
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} |
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// We only want to trace the address resolution in the follow cases:
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// (a) Address resolution resulted in service config change.
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// (b) Address resolution that causes number of backends to go from
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// zero to non-zero.
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// (c) Address resolution that causes number of backends to go from
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// non-zero to zero.
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// (d) Address resolution that causes a new LB policy to be created.
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//
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// We track a list of strings to eventually be concatenated and traced.
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TraceStringVector trace_strings; |
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MaybeAddTraceMessagesForAddressChangesLocked(!result.addresses.empty(), |
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&trace_strings); |
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// The result of grpc_error_string() is owned by the error itself.
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// We're storing that string in trace_strings, so we need to make sure
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// that the error lives until we're done with the string.
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grpc_error* service_config_error = |
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GRPC_ERROR_REF(result.service_config_error); |
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if (service_config_error != GRPC_ERROR_NONE) { |
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trace_strings.push_back(grpc_error_string(service_config_error)); |
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} |
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// Choose the service config.
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ChannelConfigHelper::ChooseServiceConfigResult service_config_result; |
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if (helper_ != nullptr) { |
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service_config_result = helper_->ChooseServiceConfig(result); |
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} else { |
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service_config_result.lb_policy_config = child_lb_config_; |
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} |
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if (service_config_result.no_valid_service_config) { |
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// We received an invalid service config and we don't have a
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// previous service config to fall back to.
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OnResolverError(GRPC_ERROR_REF(service_config_error)); |
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trace_strings.push_back("no valid service config"); |
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} else { |
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// Create or update LB policy, as needed.
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CreateOrUpdateLbPolicyLocked( |
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std::move(service_config_result.lb_policy_config), std::move(result)); |
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if (service_config_result.service_config_changed) { |
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// Tell channel to start using new service config for calls.
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// This needs to happen after the LB policy has been updated, since
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// the ConfigSelector may need the LB policy to know about new
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// destinations before it can send RPCs to those destinations.
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if (helper_ != nullptr) helper_->StartUsingServiceConfigForCalls(); |
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// TODO(ncteisen): might be worth somehow including a snippet of the
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// config in the trace, at the risk of bloating the trace logs.
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trace_strings.push_back("Service config changed"); |
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} |
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} |
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// Add channel trace event.
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ConcatenateAndAddChannelTraceLocked(trace_strings); |
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GRPC_ERROR_UNREF(service_config_error); |
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} |
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} // namespace grpc_core
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@ -1,138 +0,0 @@ |
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/*
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* |
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* Copyright 2018 gRPC authors. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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* |
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*/ |
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#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVING_LB_POLICY_H |
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#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVING_LB_POLICY_H |
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#include <grpc/support/port_platform.h> |
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#include "absl/container/inlined_vector.h" |
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#include "src/core/ext/filters/client_channel/config_selector.h" |
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#include "src/core/ext/filters/client_channel/lb_policy.h" |
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#include "src/core/ext/filters/client_channel/lb_policy_factory.h" |
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#include "src/core/ext/filters/client_channel/resolver.h" |
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#include "src/core/lib/channel/channel_args.h" |
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#include "src/core/lib/channel/channel_stack.h" |
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#include "src/core/lib/debug/trace.h" |
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#include "src/core/lib/gprpp/orphanable.h" |
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#include "src/core/lib/iomgr/call_combiner.h" |
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#include "src/core/lib/iomgr/closure.h" |
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#include "src/core/lib/iomgr/polling_entity.h" |
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#include "src/core/lib/iomgr/pollset_set.h" |
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#include "src/core/lib/transport/connectivity_state.h" |
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#include "src/core/lib/transport/metadata_batch.h" |
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namespace grpc_core { |
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// An LB policy that wraps a resolver and a child LB policy to make use
|
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// of the addresses returned by the resolver.
|
|
||||||
//
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|
||||||
// When used in the client_channel code, the resolver will attempt to
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|
||||||
// fetch the service config, and the child LB policy name and config
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|
||||||
// will be determined based on the service config.
|
|
||||||
//
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|
||||||
// When used in an LB policy implementation that needs to do another
|
|
||||||
// round of resolution before creating a child policy, the resolver does
|
|
||||||
// not fetch the service config, and the caller must pre-determine the
|
|
||||||
// child LB policy and config to use.
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|
||||||
class ResolvingLoadBalancingPolicy : public LoadBalancingPolicy { |
|
||||||
public: |
|
||||||
class ChannelConfigHelper { |
|
||||||
public: |
|
||||||
struct ChooseServiceConfigResult { |
|
||||||
// Set to true if the service config has changed since the last result.
|
|
||||||
bool service_config_changed = false; |
|
||||||
// Set to true if we don't have a valid service config to use.
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|
||||||
// This tells the ResolvingLoadBalancingPolicy to put the channel
|
|
||||||
// into TRANSIENT_FAILURE.
|
|
||||||
bool no_valid_service_config = false; |
|
||||||
// The LB policy config to use.
|
|
||||||
RefCountedPtr<LoadBalancingPolicy::Config> lb_policy_config; |
|
||||||
}; |
|
||||||
|
|
||||||
virtual ~ChannelConfigHelper() = default; |
|
||||||
|
|
||||||
// Chooses the service config for the channel.
|
|
||||||
virtual ChooseServiceConfigResult ChooseServiceConfig( |
|
||||||
const Resolver::Result& result) = 0; |
|
||||||
|
|
||||||
// Starts using the service config for calls.
|
|
||||||
virtual void StartUsingServiceConfigForCalls() = 0; |
|
||||||
|
|
||||||
// Indicates a resolver transient failure.
|
|
||||||
virtual void ResolverTransientFailure(grpc_error* error) = 0; |
|
||||||
}; |
|
||||||
|
|
||||||
ResolvingLoadBalancingPolicy(Args args, TraceFlag* tracer, |
|
||||||
grpc_core::UniquePtr<char> target_uri, |
|
||||||
ChannelConfigHelper* helper); |
|
||||||
|
|
||||||
const char* name() const override { return "resolving_lb"; } |
|
||||||
|
|
||||||
// No-op -- should never get updates from the channel.
|
|
||||||
// TODO(roth): Need to support updating child LB policy's config for xds
|
|
||||||
// use case.
|
|
||||||
void UpdateLocked(UpdateArgs /*args*/) override {} |
|
||||||
|
|
||||||
void ExitIdleLocked() override; |
|
||||||
|
|
||||||
void ResetBackoffLocked() override; |
|
||||||
|
|
||||||
private: |
|
||||||
using TraceStringVector = absl::InlinedVector<const char*, 3>; |
|
||||||
|
|
||||||
class ResolverResultHandler; |
|
||||||
class ResolvingControlHelper; |
|
||||||
|
|
||||||
~ResolvingLoadBalancingPolicy() override; |
|
||||||
|
|
||||||
void ShutdownLocked() override; |
|
||||||
|
|
||||||
void OnResolverError(grpc_error* error); |
|
||||||
void CreateOrUpdateLbPolicyLocked( |
|
||||||
RefCountedPtr<LoadBalancingPolicy::Config> lb_policy_config, |
|
||||||
Resolver::Result result); |
|
||||||
OrphanablePtr<LoadBalancingPolicy> CreateLbPolicyLocked( |
|
||||||
const grpc_channel_args& args); |
|
||||||
void MaybeAddTraceMessagesForAddressChangesLocked( |
|
||||||
bool resolution_contains_addresses, TraceStringVector* trace_strings); |
|
||||||
void ConcatenateAndAddChannelTraceLocked( |
|
||||||
const TraceStringVector& trace_strings) const; |
|
||||||
void OnResolverResultChangedLocked(Resolver::Result result); |
|
||||||
|
|
||||||
// Passed in from caller at construction time.
|
|
||||||
TraceFlag* tracer_; |
|
||||||
grpc_core::UniquePtr<char> target_uri_; |
|
||||||
ChannelConfigHelper* helper_; |
|
||||||
|
|
||||||
// Resolver and associated state.
|
|
||||||
OrphanablePtr<Resolver> resolver_; |
|
||||||
bool previous_resolution_contained_addresses_ = false; |
|
||||||
|
|
||||||
// Determined by resolver results.
|
|
||||||
grpc_core::UniquePtr<char> child_policy_name_; |
|
||||||
RefCountedPtr<LoadBalancingPolicy::Config> child_lb_config_; |
|
||||||
|
|
||||||
// Child LB policy.
|
|
||||||
OrphanablePtr<LoadBalancingPolicy> lb_policy_; |
|
||||||
}; |
|
||||||
|
|
||||||
} // namespace grpc_core
|
|
||||||
|
|
||||||
#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVING_LB_POLICY_H */ |
|
||||||
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Reference in new issue