[VOL-4289] Proto changes for gRPC migration
Change-Id: I317a0a865ccf78d0c37aa229c50d293a3f66c8bb
diff --git a/vendor/google.golang.org/grpc/balancer/balancer.go b/vendor/google.golang.org/grpc/balancer/balancer.go
new file mode 100644
index 0000000..178de08
--- /dev/null
+++ b/vendor/google.golang.org/grpc/balancer/balancer.go
@@ -0,0 +1,418 @@
+/*
+ *
+ * Copyright 2017 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 defines APIs for load balancing in gRPC.
+// All APIs in this package are experimental.
+package balancer
+
+import (
+ "context"
+ "encoding/json"
+ "errors"
+ "net"
+ "strings"
+
+ "google.golang.org/grpc/connectivity"
+ "google.golang.org/grpc/credentials"
+ "google.golang.org/grpc/internal"
+ "google.golang.org/grpc/metadata"
+ "google.golang.org/grpc/resolver"
+ "google.golang.org/grpc/serviceconfig"
+)
+
+var (
+ // m is a map from name to balancer builder.
+ m = make(map[string]Builder)
+)
+
+// Register registers the balancer builder to the balancer map. b.Name
+// (lowercased) will be used as the name registered with this builder. If the
+// Builder implements ConfigParser, ParseConfig will be called when new service
+// configs are received by the resolver, and the result will be provided to the
+// Balancer in UpdateClientConnState.
+//
+// NOTE: this function must only be called during initialization time (i.e. in
+// an init() function), and is not thread-safe. If multiple Balancers are
+// registered with the same name, the one registered last will take effect.
+func Register(b Builder) {
+ m[strings.ToLower(b.Name())] = b
+}
+
+// unregisterForTesting deletes the balancer with the given name from the
+// balancer map.
+//
+// This function is not thread-safe.
+func unregisterForTesting(name string) {
+ delete(m, name)
+}
+
+func init() {
+ internal.BalancerUnregister = unregisterForTesting
+}
+
+// Get returns the resolver builder registered with the given name.
+// Note that the compare is done in a case-insensitive fashion.
+// If no builder is register with the name, nil will be returned.
+func Get(name string) Builder {
+ if b, ok := m[strings.ToLower(name)]; ok {
+ return b
+ }
+ return nil
+}
+
+// A SubConn represents a single connection to a gRPC backend service.
+//
+// Each SubConn contains a list of addresses.
+//
+// All SubConns start in IDLE, and will not try to connect. To trigger the
+// connecting, Balancers must call Connect. If a connection re-enters IDLE,
+// Balancers must call Connect again to trigger a new connection attempt.
+//
+// gRPC will try to connect to the addresses in sequence, and stop trying the
+// remainder once the first connection is successful. If an attempt to connect
+// to all addresses encounters an error, the SubConn will enter
+// TRANSIENT_FAILURE for a backoff period, and then transition to IDLE.
+//
+// Once established, if a connection is lost, the SubConn will transition
+// directly to IDLE.
+//
+// This interface is to be implemented by gRPC. Users should not need their own
+// implementation of this interface. For situations like testing, any
+// implementations should embed this interface. This allows gRPC to add new
+// methods to this interface.
+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 closed, and
+ // a new connection will be created.
+ //
+ // This will trigger a state transition for the SubConn.
+ //
+ // Deprecated: This method is now part of the ClientConn interface and will
+ // eventually be removed from here.
+ UpdateAddresses([]resolver.Address)
+ // Connect starts the connecting for this SubConn.
+ Connect()
+}
+
+// NewSubConnOptions contains options to create new SubConn.
+type NewSubConnOptions struct {
+ // CredsBundle is the credentials bundle that will be used in the created
+ // SubConn. If it's nil, the original creds from grpc DialOptions will be
+ // used.
+ //
+ // Deprecated: Use the Attributes field in resolver.Address to pass
+ // arbitrary data to the credential handshaker.
+ CredsBundle credentials.Bundle
+ // HealthCheckEnabled indicates whether health check service should be
+ // enabled on this SubConn
+ HealthCheckEnabled bool
+}
+
+// State contains the balancer's state relevant to the gRPC ClientConn.
+type State struct {
+ // State contains the connectivity state of the balancer, which is used to
+ // determine the state of the ClientConn.
+ ConnectivityState connectivity.State
+ // Picker is used to choose connections (SubConns) for RPCs.
+ Picker Picker
+}
+
+// ClientConn represents a gRPC ClientConn.
+//
+// This interface is to be implemented by gRPC. Users should not need a
+// brand new implementation of this interface. For the situations like
+// testing, the new implementation should embed this interface. This allows
+// gRPC to add new methods to this interface.
+type ClientConn interface {
+ // NewSubConn is called by balancer to create a new SubConn.
+ // It doesn't block and wait for the connections to be established.
+ // Behaviors of the SubConn can be controlled by options.
+ NewSubConn([]resolver.Address, NewSubConnOptions) (SubConn, error)
+ // RemoveSubConn removes the SubConn from ClientConn.
+ // The SubConn will be shutdown.
+ RemoveSubConn(SubConn)
+ // UpdateAddresses updates the addresses used in the passed in SubConn.
+ // gRPC checks if the currently connected address is still in the new list.
+ // If so, the connection will be kept. Else, the connection will be
+ // gracefully closed, and a new connection will be created.
+ //
+ // This will trigger a state transition for the SubConn.
+ UpdateAddresses(SubConn, []resolver.Address)
+
+ // UpdateState notifies gRPC that the balancer's internal state has
+ // changed.
+ //
+ // gRPC will update the connectivity state of the ClientConn, and will call
+ // Pick on the new Picker to pick new SubConns.
+ UpdateState(State)
+
+ // ResolveNow is called by balancer to notify gRPC to do a name resolving.
+ ResolveNow(resolver.ResolveNowOptions)
+
+ // Target returns the dial target for this ClientConn.
+ //
+ // Deprecated: Use the Target field in the BuildOptions instead.
+ Target() string
+}
+
+// BuildOptions contains additional information for Build.
+type BuildOptions struct {
+ // DialCreds is the transport credential the Balancer implementation can
+ // use to dial to a remote load balancer server. The Balancer implementations
+ // can ignore this if it does not need to talk to another party securely.
+ DialCreds credentials.TransportCredentials
+ // CredsBundle is the credentials bundle that the Balancer can use.
+ CredsBundle credentials.Bundle
+ // Dialer is the custom dialer the Balancer implementation can use to dial
+ // to a remote load balancer server. The Balancer implementations
+ // can ignore this if it doesn't need to talk to remote balancer.
+ Dialer func(context.Context, string) (net.Conn, error)
+ // ChannelzParentID is the entity parent's channelz unique identification number.
+ ChannelzParentID int64
+ // CustomUserAgent is the custom user agent set on the parent ClientConn.
+ // The balancer should set the same custom user agent if it creates a
+ // ClientConn.
+ CustomUserAgent string
+ // Target contains the parsed address info of the dial target. It is the same resolver.Target as
+ // passed to the resolver.
+ // See the documentation for the resolver.Target type for details about what it contains.
+ Target resolver.Target
+}
+
+// Builder creates a balancer.
+type Builder interface {
+ // Build creates a new balancer with the ClientConn.
+ Build(cc ClientConn, opts BuildOptions) Balancer
+ // Name returns the name of balancers built by this builder.
+ // It will be used to pick balancers (for example in service config).
+ Name() string
+}
+
+// ConfigParser parses load balancer configs.
+type ConfigParser interface {
+ // ParseConfig parses the JSON load balancer config provided into an
+ // internal form or returns an error if the config is invalid. For future
+ // compatibility reasons, unknown fields in the config should be ignored.
+ ParseConfig(LoadBalancingConfigJSON json.RawMessage) (serviceconfig.LoadBalancingConfig, error)
+}
+
+// PickInfo contains additional information for the Pick operation.
+type PickInfo struct {
+ // FullMethodName is the method name that NewClientStream() is called
+ // with. The canonical format is /service/Method.
+ FullMethodName string
+ // Ctx is the RPC's context, and may contain relevant RPC-level information
+ // like the outgoing header metadata.
+ Ctx context.Context
+}
+
+// DoneInfo contains additional information for done.
+type DoneInfo struct {
+ // Err is the rpc error the RPC finished with. It could be nil.
+ Err error
+ // Trailer contains the metadata from the RPC's trailer, if present.
+ Trailer metadata.MD
+ // BytesSent indicates if any bytes have been sent to the server.
+ BytesSent bool
+ // BytesReceived indicates if any byte has been received from the server.
+ BytesReceived bool
+ // ServerLoad is the load received from server. It's usually sent as part of
+ // trailing metadata.
+ //
+ // The only supported type now is *orca_v1.LoadReport.
+ ServerLoad interface{}
+}
+
+var (
+ // ErrNoSubConnAvailable indicates no SubConn is available for pick().
+ // gRPC will block the RPC until a new picker is available via UpdateState().
+ ErrNoSubConnAvailable = errors.New("no SubConn is available")
+ // ErrTransientFailure indicates all SubConns are in TransientFailure.
+ // WaitForReady RPCs will block, non-WaitForReady RPCs will fail.
+ //
+ // Deprecated: return an appropriate error based on the last resolution or
+ // connection attempt instead. The behavior is the same for any non-gRPC
+ // status error.
+ ErrTransientFailure = errors.New("all SubConns are in TransientFailure")
+)
+
+// PickResult contains information related to a connection chosen for an RPC.
+type PickResult struct {
+ // SubConn is the connection to use for this pick, if its state is Ready.
+ // If the state is not Ready, gRPC will block the RPC until a new Picker is
+ // provided by the balancer (using ClientConn.UpdateState). The SubConn
+ // must be one returned by ClientConn.NewSubConn.
+ SubConn SubConn
+
+ // Done is called when the RPC is completed. If the SubConn is not ready,
+ // this will be called with a nil parameter. If the SubConn is not a valid
+ // type, Done may not be called. May be nil if the balancer does not wish
+ // to be notified when the RPC completes.
+ Done func(DoneInfo)
+}
+
+// TransientFailureError returns e. It exists for backward compatibility and
+// will be deleted soon.
+//
+// Deprecated: no longer necessary, picker errors are treated this way by
+// default.
+func TransientFailureError(e error) error { return e }
+
+// Picker is used by gRPC to pick a SubConn to send an RPC.
+// Balancer is expected to generate a new picker from its snapshot every time its
+// internal state has changed.
+//
+// The pickers used by gRPC can be updated by ClientConn.UpdateState().
+type Picker interface {
+ // Pick returns the connection to use for this RPC and related information.
+ //
+ // Pick should not block. If the balancer needs to do I/O or any blocking
+ // or time-consuming work to service this call, it should return
+ // ErrNoSubConnAvailable, and the Pick call will be repeated by gRPC when
+ // the Picker is updated (using ClientConn.UpdateState).
+ //
+ // If an error is returned:
+ //
+ // - If the error is ErrNoSubConnAvailable, gRPC will block until a new
+ // Picker is provided by the balancer (using ClientConn.UpdateState).
+ //
+ // - If the error is a status error (implemented by the grpc/status
+ // package), gRPC will terminate the RPC with the code and message
+ // provided.
+ //
+ // - For all other errors, wait for ready RPCs will wait, but non-wait for
+ // ready RPCs will be terminated with this error's Error() string and
+ // status code Unavailable.
+ Pick(info PickInfo) (PickResult, error)
+}
+
+// Balancer takes input from gRPC, manages SubConns, and collects and aggregates
+// the connectivity states.
+//
+// It also generates and updates the Picker used by gRPC to pick SubConns for RPCs.
+//
+// UpdateClientConnState, ResolverError, UpdateSubConnState, and Close are
+// guaranteed to be called synchronously from the same goroutine. There's no
+// guarantee on picker.Pick, it may be called anytime.
+type Balancer interface {
+ // UpdateClientConnState is called by gRPC when the state of the ClientConn
+ // changes. If the error returned is ErrBadResolverState, the ClientConn
+ // will begin calling ResolveNow on the active name resolver with
+ // exponential backoff until a subsequent call to UpdateClientConnState
+ // returns a nil error. Any other errors are currently ignored.
+ UpdateClientConnState(ClientConnState) error
+ // ResolverError is called by gRPC when the name resolver reports an error.
+ ResolverError(error)
+ // UpdateSubConnState is called by gRPC when the state of a SubConn
+ // changes.
+ UpdateSubConnState(SubConn, SubConnState)
+ // Close closes the balancer. The balancer is not required to call
+ // ClientConn.RemoveSubConn for its existing SubConns.
+ Close()
+}
+
+// ExitIdler is an optional interface for balancers to implement. If
+// implemented, ExitIdle will be called when ClientConn.Connect is called, if
+// the ClientConn is idle. If unimplemented, ClientConn.Connect will cause
+// all SubConns to connect.
+//
+// Notice: it will be required for all balancers to implement this in a future
+// release.
+type ExitIdler interface {
+ // ExitIdle instructs the LB policy to reconnect to backends / exit the
+ // IDLE state, if appropriate and possible. Note that SubConns that enter
+ // the IDLE state will not reconnect until SubConn.Connect is called.
+ ExitIdle()
+}
+
+// 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
+}
+
+// ClientConnState describes the state of a ClientConn relevant to the
+// balancer.
+type ClientConnState struct {
+ ResolverState resolver.State
+ // The parsed load balancing configuration returned by the builder's
+ // ParseConfig method, if implemented.
+ BalancerConfig serviceconfig.LoadBalancingConfig
+}
+
+// ErrBadResolverState may be returned by UpdateClientConnState to indicate a
+// problem with the provided name resolver data.
+var ErrBadResolverState = errors.New("bad resolver state")
+
+// ConnectivityStateEvaluator takes the connectivity states of multiple SubConns
+// and returns one aggregated connectivity state.
+//
+// It's not thread safe.
+type ConnectivityStateEvaluator struct {
+ numReady uint64 // Number of addrConns in ready state.
+ numConnecting uint64 // Number of addrConns in connecting state.
+ numTransientFailure uint64 // Number of addrConns in transient failure state.
+ numIdle uint64 // Number of addrConns in idle state.
+}
+
+// RecordTransition records state change happening in subConn and based on that
+// it evaluates what aggregated state should be.
+//
+// - If at least one SubConn in Ready, the aggregated state is Ready;
+// - Else if at least one SubConn in Connecting, the aggregated state is Connecting;
+// - Else if at least one SubConn is TransientFailure, the aggregated state is Transient Failure;
+// - Else if at least one SubConn is Idle, the aggregated state is Idle;
+// - Else there are no subconns and the aggregated state is Transient Failure
+//
+// Shutdown is not considered.
+func (cse *ConnectivityStateEvaluator) RecordTransition(oldState, newState connectivity.State) connectivity.State {
+ // Update counters.
+ for idx, state := range []connectivity.State{oldState, newState} {
+ updateVal := 2*uint64(idx) - 1 // -1 for oldState and +1 for new.
+ switch state {
+ case connectivity.Ready:
+ cse.numReady += updateVal
+ case connectivity.Connecting:
+ cse.numConnecting += updateVal
+ case connectivity.TransientFailure:
+ cse.numTransientFailure += updateVal
+ case connectivity.Idle:
+ cse.numIdle += updateVal
+ }
+ }
+
+ // Evaluate.
+ if cse.numReady > 0 {
+ return connectivity.Ready
+ }
+ if cse.numConnecting > 0 {
+ return connectivity.Connecting
+ }
+ if cse.numTransientFailure > 0 {
+ return connectivity.TransientFailure
+ }
+ if cse.numIdle > 0 {
+ return connectivity.Idle
+ }
+ return connectivity.TransientFailure
+}