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Diffstat (limited to 'vendor/google.golang.org/grpc/balancer/subconn.go')
| -rw-r--r-- | vendor/google.golang.org/grpc/balancer/subconn.go | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/vendor/google.golang.org/grpc/balancer/subconn.go b/vendor/google.golang.org/grpc/balancer/subconn.go new file mode 100644 index 000000000..ea27c4fa7 --- /dev/null +++ b/vendor/google.golang.org/grpc/balancer/subconn.go @@ -0,0 +1,134 @@ +/* + * + * Copyright 2024 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. + * + */ + +package balancer + +import ( + "google.golang.org/grpc/connectivity" + "google.golang.org/grpc/internal" + "google.golang.org/grpc/resolver" +) + +// A SubConn represents a single connection to a gRPC backend service. +// +// All SubConns start in IDLE, and will not try to connect. To trigger a +// connection attempt, Balancers must call Connect. +// +// If the connection attempt fails, the SubConn will transition to +// TRANSIENT_FAILURE for a backoff period, and then return to IDLE. If the +// connection attempt succeeds, it will transition to READY. +// +// If a READY SubConn becomes disconnected, the SubConn will transition to IDLE. +// +// If a connection re-enters IDLE, Balancers must call Connect again to trigger +// a new connection attempt. +// +// Each SubConn contains a list of addresses. gRPC will try to connect to the +// addresses in sequence, and stop trying the remainder once the first +// connection is successful. However, this behavior is deprecated. SubConns +// should only use a single address. +// +// NOTICE: This interface is intended to be implemented by gRPC, or intercepted +// by custom load balancing poilices. Users should not need their own complete +// implementation of this interface -- they should always delegate to a SubConn +// returned by ClientConn.NewSubConn() by embedding it in their implementations. +// An embedded SubConn must never be nil, or runtime panics will occur. +type SubConn interface { + // UpdateAddresses updates the addresses used in this SubConn. + // gRPC checks if currently-connected address is still in the new list. + // If it's in the list, the connection will be kept. + // If it's not in the list, the connection will gracefully close, and + // a new connection will be created. + // + // This will trigger a state transition for the SubConn. + // + // Deprecated: this method will be removed. Create new SubConns for new + // addresses instead. + UpdateAddresses([]resolver.Address) + // Connect starts the connecting for this SubConn. + Connect() + // GetOrBuildProducer returns a reference to the existing Producer for this + // ProducerBuilder in this SubConn, or, if one does not currently exist, + // creates a new one and returns it. Returns a close function which may be + // called when the Producer is no longer needed. Otherwise the producer + // will automatically be closed upon connection loss or subchannel close. + // Should only be called on a SubConn in state Ready. Otherwise the + // producer will be unable to create streams. + GetOrBuildProducer(ProducerBuilder) (p Producer, close func()) + // Shutdown shuts down the SubConn gracefully. Any started RPCs will be + // allowed to complete. No future calls should be made on the SubConn. + // One final state update will be delivered to the StateListener (or + // UpdateSubConnState; deprecated) with ConnectivityState of Shutdown to + // indicate the shutdown operation. This may be delivered before + // in-progress RPCs are complete and the actual connection is closed. + Shutdown() + // RegisterHealthListener registers a health listener that receives health + // updates for a Ready SubConn. Only one health listener can be registered + // at a time. A health listener should be registered each time the SubConn's + // connectivity state changes to READY. Registering a health listener when + // the connectivity state is not READY may result in undefined behaviour. + // This method must not be called synchronously while handling an update + // from a previously registered health listener. + RegisterHealthListener(func(SubConnState)) + // EnforceSubConnEmbedding is included to force implementers to embed + // another implementation of this interface, allowing gRPC to add methods + // without breaking users. + internal.EnforceSubConnEmbedding +} + +// A ProducerBuilder is a simple constructor for a Producer. It is used by the +// SubConn to create producers when needed. +type ProducerBuilder interface { + // Build creates a Producer. The first parameter is always a + // grpc.ClientConnInterface (a type to allow creating RPCs/streams on the + // associated SubConn), but is declared as `any` to avoid a dependency + // cycle. Build also returns a close function that will be called when all + // references to the Producer have been given up for a SubConn, or when a + // connectivity state change occurs on the SubConn. The close function + // should always block until all asynchronous cleanup work is completed. + Build(grpcClientConnInterface any) (p Producer, close func()) +} + +// SubConnState describes the state of a SubConn. +type SubConnState struct { + // ConnectivityState is the connectivity state of the SubConn. + ConnectivityState connectivity.State + // ConnectionError is set if the ConnectivityState is TransientFailure, + // describing the reason the SubConn failed. Otherwise, it is nil. + ConnectionError error + // connectedAddr contains the connected address when ConnectivityState is + // Ready. Otherwise, it is indeterminate. + connectedAddress resolver.Address +} + +// connectedAddress returns the connected address for a SubConnState. The +// address is only valid if the state is READY. +func connectedAddress(scs SubConnState) resolver.Address { + return scs.connectedAddress +} + +// setConnectedAddress sets the connected address for a SubConnState. +func setConnectedAddress(scs *SubConnState, addr resolver.Address) { + scs.connectedAddress = addr +} + +// A Producer is a type shared among potentially many consumers. It is +// associated with a SubConn, and an implementation will typically contain +// other methods to provide additional functionality, e.g. configuration or +// subscription registration. +type Producer any |