diff --git a/go/internal/balancer/BUILD.bazel b/go/internal/balancer/BUILD.bazel new file mode 100644 index 000000000..4207ec0c9 --- /dev/null +++ b/go/internal/balancer/BUILD.bazel @@ -0,0 +1,16 @@ +load("@io_bazel_rules_go//go:def.bzl", "go_library") + +go_library( + name = "balancer", + srcs = ["balancer.go"], + importpath = "github.com/bazelbuild/remote-apis-sdks/go/internal/balancer", + visibility = ["//go:__subpackages__"], + deps = [ + "//go/internal/resolver", + "@org_golang_google_grpc//channelz", + "@org_golang_google_grpc//connectivity", + "@org_golang_google_grpc//credentials", + "@org_golang_google_grpc//metadata", + "@org_golang_google_grpc//serviceconfig", + ], +) diff --git a/go/internal/balancer/balancer.go b/go/internal/balancer/balancer.go new file mode 100644 index 000000000..6f222ef8a --- /dev/null +++ b/go/internal/balancer/balancer.go @@ -0,0 +1,430 @@ +// This file was copied from https://github.com/grpc/grpc-go/blob/b0a946cf0cf1adb094d7da9dbf2d054905702c73/balancer/balancer.go +// to avoid depending on an experimental API. See #499. + +/* + * + * 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" + + "github.com/bazelbuild/remote-apis-sdks/go/internal/resolver" + "google.golang.org/grpc/channelz" + "google.golang.org/grpc/connectivity" + "google.golang.org/grpc/credentials" + "google.golang.org/grpc/metadata" + "google.golang.org/grpc/serviceconfig" +) + +var ( + // m is a map from name to balancer builder. + m = make(map[string]Builder) + BalancerUnregister func(name string) +) + +// 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() { + 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 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 must + // be called when the Producer is no longer needed. + 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() +} + +// 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 + // StateListener is called when the state of the subconn changes. If nil, + // Balancer.UpdateSubConnState will be called instead. Will never be + // invoked until after Connect() is called on the SubConn created with + // these options. + StateListener func(SubConnState) +} + +// 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. + // + // Deprecated: please be aware that in a future version, SubConns will only + // support one address per SubConn. + NewSubConn([]resolver.Address, NewSubConnOptions) (SubConn, error) + // RemoveSubConn removes the SubConn from ClientConn. + // The SubConn will be shutdown. + // + // Deprecated: use SubConn.Shutdown instead. + 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 may trigger a state transition for the SubConn. + // + // Deprecated: this method will be removed. Create new SubConns for new + // addresses instead. + 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 credentials to use when communicating with a + // remote load balancer server. Balancer implementations which do not + // communicate with a remote load balancer server can ignore this field. + DialCreds credentials.TransportCredentials + // CredsBundle is the credentials bundle to use when communicating with a + // remote load balancer server. Balancer implementations which do not + // communicate with a remote load balancer server can ignore this field. + CredsBundle credentials.Bundle + // Dialer is the custom dialer to use when communicating with a remote load + // balancer server. Balancer implementations which do not communicate with a + // remote load balancer server can ignore this field. + Dialer func(context.Context, string) (net.Conn, error) + // Authority is the server name to use as part of the authentication + // handshake when communicating with a remote load balancer server. Balancer + // implementations which do not communicate with a remote load balancer + // server can ignore this field. + Authority string + // ChannelzParentID is the parent ClientConn's channelz ID. + ChannelzParentID *channelz.Identifier + // 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_v3.LoadReport. + ServerLoad any +} + +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) + + // Metadata provides a way for LB policies to inject arbitrary per-call + // metadata. Any metadata returned here will be merged with existing + // metadata added by the client application. + // + // LB policies with child policies are responsible for propagating metadata + // injected by their children to the ClientConn, as part of Pick(). + Metadata metadata.MD +} + +// 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. + // + // Deprecated: Use NewSubConnOptions.StateListener when creating the + // SubConn instead. + UpdateSubConnState(SubConn, SubConnState) + // Close closes the balancer. The balancer is not currently required to + // call SubConn.Shutdown for its existing SubConns; however, this will be + // required in a future release, so it is recommended. + 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") + +// 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. Should also return a close function that will be called when all + // references to the Producer have been given up. + Build(grpcClientConnInterface any) (p Producer, close func()) +} + +// 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 diff --git a/go/internal/resolver/BUILD.bazel b/go/internal/resolver/BUILD.bazel new file mode 100644 index 000000000..92f3994bb --- /dev/null +++ b/go/internal/resolver/BUILD.bazel @@ -0,0 +1,13 @@ +load("@io_bazel_rules_go//go:def.bzl", "go_library") + +go_library( + name = "resolver", + srcs = ["resolver.go"], + importpath = "github.com/bazelbuild/remote-apis-sdks/go/internal/resolver", + visibility = ["//go:__subpackages__"], + deps = [ + "@org_golang_google_grpc//attributes", + "@org_golang_google_grpc//credentials", + "@org_golang_google_grpc//serviceconfig", + ], +) diff --git a/go/internal/resolver/resolver.go b/go/internal/resolver/resolver.go new file mode 100644 index 000000000..f7b11669b --- /dev/null +++ b/go/internal/resolver/resolver.go @@ -0,0 +1,319 @@ +// This file was copied from https://github.com/grpc/grpc-go/blob/b0a946cf0cf1adb094d7da9dbf2d054905702c73/resolver/resolver.go +// to avoid depending on an experimental API. See #499. + +/* + * + * 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 resolver defines APIs for name resolution in gRPC. +// All APIs in this package are experimental. +package resolver + +import ( + "context" + "fmt" + "net" + "net/url" + "strings" + + "google.golang.org/grpc/attributes" + "google.golang.org/grpc/credentials" + "google.golang.org/grpc/serviceconfig" +) + +var ( + // m is a map from scheme to resolver builder. + m = make(map[string]Builder) + // defaultScheme is the default scheme to use. + defaultScheme = "passthrough" +) + +// TODO(bar) install dns resolver in init(){}. + +// Register registers the resolver builder to the resolver map. b.Scheme will +// be used as the scheme registered with this builder. The registry is case +// sensitive, and schemes should not contain any uppercase characters. +// +// NOTE: this function must only be called during initialization time (i.e. in +// an init() function), and is not thread-safe. If multiple Resolvers are +// registered with the same name, the one registered last will take effect. +func Register(b Builder) { + m[b.Scheme()] = b +} + +// Get returns the resolver builder registered with the given scheme. +// +// If no builder is register with the scheme, nil will be returned. +func Get(scheme string) Builder { + if b, ok := m[scheme]; ok { + return b + } + return nil +} + +// SetDefaultScheme sets the default scheme that will be used. The default +// default scheme is "passthrough". +// +// NOTE: this function must only be called during initialization time (i.e. in +// an init() function), and is not thread-safe. The scheme set last overrides +// previously set values. +func SetDefaultScheme(scheme string) { + defaultScheme = scheme +} + +// GetDefaultScheme gets the default scheme that will be used. +func GetDefaultScheme() string { + return defaultScheme +} + +// Address represents a server the client connects to. +// +// # Experimental +// +// Notice: This type is EXPERIMENTAL and may be changed or removed in a +// later release. +type Address struct { + // Addr is the server address on which a connection will be established. + Addr string + + // ServerName is the name of this address. + // If non-empty, the ServerName is used as the transport certification authority for + // the address, instead of the hostname from the Dial target string. In most cases, + // this should not be set. + // + // WARNING: ServerName must only be populated with trusted values. It + // is insecure to populate it with data from untrusted inputs since untrusted + // values could be used to bypass the authority checks performed by TLS. + ServerName string + + // Attributes contains arbitrary data about this address intended for + // consumption by the SubConn. + Attributes *attributes.Attributes + + // BalancerAttributes contains arbitrary data about this address intended + // for consumption by the LB policy. These attributes do not affect SubConn + // creation, connection establishment, handshaking, etc. + // + // Deprecated: when an Address is inside an Endpoint, this field should not + // be used, and it will eventually be removed entirely. + BalancerAttributes *attributes.Attributes + + // Metadata is the information associated with Addr, which may be used + // to make load balancing decision. + // + // Deprecated: use Attributes instead. + Metadata any +} + +// Equal returns whether a and o are identical. Metadata is compared directly, +// not with any recursive introspection. +// +// This method compares all fields of the address. When used to tell apart +// addresses during subchannel creation or connection establishment, it might be +// more appropriate for the caller to implement custom equality logic. +func (a Address) Equal(o Address) bool { + return a.Addr == o.Addr && a.ServerName == o.ServerName && + a.Attributes.Equal(o.Attributes) && + a.BalancerAttributes.Equal(o.BalancerAttributes) && + a.Metadata == o.Metadata +} + +// String returns JSON formatted string representation of the address. +func (a Address) String() string { + var sb strings.Builder + sb.WriteString(fmt.Sprintf("{Addr: %q, ", a.Addr)) + sb.WriteString(fmt.Sprintf("ServerName: %q, ", a.ServerName)) + if a.Attributes != nil { + sb.WriteString(fmt.Sprintf("Attributes: %v, ", a.Attributes.String())) + } + if a.BalancerAttributes != nil { + sb.WriteString(fmt.Sprintf("BalancerAttributes: %v", a.BalancerAttributes.String())) + } + sb.WriteString("}") + return sb.String() +} + +// BuildOptions includes additional information for the builder to create +// the resolver. +type BuildOptions struct { + // DisableServiceConfig indicates whether a resolver implementation should + // fetch service config data. + DisableServiceConfig bool + // DialCreds is the transport credentials used by the ClientConn for + // communicating with the target gRPC service (set via + // WithTransportCredentials). In cases where a name resolution service + // requires the same credentials, the resolver may use this field. In most + // cases though, it is not appropriate, and this field may be ignored. + DialCreds credentials.TransportCredentials + // CredsBundle is the credentials bundle used by the ClientConn for + // communicating with the target gRPC service (set via + // WithCredentialsBundle). In cases where a name resolution service + // requires the same credentials, the resolver may use this field. In most + // cases though, it is not appropriate, and this field may be ignored. + CredsBundle credentials.Bundle + // Dialer is the custom dialer used by the ClientConn for dialling the + // target gRPC service (set via WithDialer). In cases where a name + // resolution service requires the same dialer, the resolver may use this + // field. In most cases though, it is not appropriate, and this field may + // be ignored. + Dialer func(context.Context, string) (net.Conn, error) +} + +// An Endpoint is one network endpoint, or server, which may have multiple +// addresses with which it can be accessed. +type Endpoint struct { + // Addresses contains a list of addresses used to access this endpoint. + Addresses []Address + + // Attributes contains arbitrary data about this endpoint intended for + // consumption by the LB policy. + Attributes *attributes.Attributes +} + +// State contains the current Resolver state relevant to the ClientConn. +type State struct { + // Addresses is the latest set of resolved addresses for the target. + // + // If a resolver sets Addresses but does not set Endpoints, one Endpoint + // will be created for each Address before the State is passed to the LB + // policy. The BalancerAttributes of each entry in Addresses will be set + // in Endpoints.Attributes, and be cleared in the Endpoint's Address's + // BalancerAttributes. + // + // Soon, Addresses will be deprecated and replaced fully by Endpoints. + Addresses []Address + + // Endpoints is the latest set of resolved endpoints for the target. + // + // If a resolver produces a State containing Endpoints but not Addresses, + // it must take care to ensure the LB policies it selects will support + // Endpoints. + Endpoints []Endpoint + + // ServiceConfig contains the result from parsing the latest service + // config. If it is nil, it indicates no service config is present or the + // resolver does not provide service configs. + ServiceConfig *serviceconfig.ParseResult + + // Attributes contains arbitrary data about the resolver intended for + // consumption by the load balancing policy. + Attributes *attributes.Attributes +} + +// ClientConn contains the callbacks for resolver to notify any updates +// to the 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 { + // UpdateState updates the state of the ClientConn appropriately. + // + // If an error is returned, the resolver should try to resolve the + // target again. The resolver should use a backoff timer to prevent + // overloading the server with requests. If a resolver is certain that + // reresolving will not change the result, e.g. because it is + // a watch-based resolver, returned errors can be ignored. + // + // If the resolved State is the same as the last reported one, calling + // UpdateState can be omitted. + UpdateState(State) error + // ReportError notifies the ClientConn that the Resolver encountered an + // error. The ClientConn will notify the load balancer and begin calling + // ResolveNow on the Resolver with exponential backoff. + ReportError(error) + // NewAddress is called by resolver to notify ClientConn a new list + // of resolved addresses. + // The address list should be the complete list of resolved addresses. + // + // Deprecated: Use UpdateState instead. + NewAddress(addresses []Address) + // NewServiceConfig is called by resolver to notify ClientConn a new + // service config. The service config should be provided as a json string. + // + // Deprecated: Use UpdateState instead. + NewServiceConfig(serviceConfig string) + // ParseServiceConfig parses the provided service config and returns an + // object that provides the parsed config. + ParseServiceConfig(serviceConfigJSON string) *serviceconfig.ParseResult +} + +// Target represents a target for gRPC, as specified in: +// https://github.com/grpc/grpc/blob/master/doc/naming.md. +// It is parsed from the target string that gets passed into Dial or DialContext +// by the user. And gRPC passes it to the resolver and the balancer. +// +// If the target follows the naming spec, and the parsed scheme is registered +// with gRPC, we will parse the target string according to the spec. If the +// target does not contain a scheme or if the parsed scheme is not registered +// (i.e. no corresponding resolver available to resolve the endpoint), we will +// apply the default scheme, and will attempt to reparse it. +type Target struct { + // URL contains the parsed dial target with an optional default scheme added + // to it if the original dial target contained no scheme or contained an + // unregistered scheme. Any query params specified in the original dial + // target can be accessed from here. + URL url.URL +} + +// Endpoint retrieves endpoint without leading "/" from either `URL.Path` +// or `URL.Opaque`. The latter is used when the former is empty. +func (t Target) Endpoint() string { + endpoint := t.URL.Path + if endpoint == "" { + endpoint = t.URL.Opaque + } + // For targets of the form "[scheme]://[authority]/endpoint, the endpoint + // value returned from url.Parse() contains a leading "/". Although this is + // in accordance with RFC 3986, we do not want to break existing resolver + // implementations which expect the endpoint without the leading "/". So, we + // end up stripping the leading "/" here. But this will result in an + // incorrect parsing for something like "unix:///path/to/socket". Since we + // own the "unix" resolver, we can workaround in the unix resolver by using + // the `URL` field. + return strings.TrimPrefix(endpoint, "/") +} + +// Builder creates a resolver that will be used to watch name resolution updates. +type Builder interface { + // Build creates a new resolver for the given target. + // + // gRPC dial calls Build synchronously, and fails if the returned error is + // not nil. + Build(target Target, cc ClientConn, opts BuildOptions) (Resolver, error) + // Scheme returns the scheme supported by this resolver. Scheme is defined + // at https://github.com/grpc/grpc/blob/master/doc/naming.md. The returned + // string should not contain uppercase characters, as they will not match + // the parsed target's scheme as defined in RFC 3986. + Scheme() string +} + +// ResolveNowOptions includes additional information for ResolveNow. +type ResolveNowOptions struct{} + +// Resolver watches for the updates on the specified target. +// Updates include address updates and service config updates. +type Resolver interface { + // ResolveNow will be called by gRPC to try to resolve the target name + // again. It's just a hint, resolver can ignore this if it's not necessary. + // + // It could be called multiple times concurrently. + ResolveNow(ResolveNowOptions) + // Close closes the resolver. + Close() +} diff --git a/go/pkg/balancer/BUILD.bazel b/go/pkg/balancer/BUILD.bazel index 4470a66b7..b4ff0ad80 100644 --- a/go/pkg/balancer/BUILD.bazel +++ b/go/pkg/balancer/BUILD.bazel @@ -11,11 +11,11 @@ go_library( visibility = ["//visibility:public"], deps = [ "//go/pkg/balancer/proto", + "//go/internal/balancer", + "//go/internal/resolver", "@org_golang_google_grpc//:go_default_library", - "@org_golang_google_grpc//balancer:go_default_library", "@org_golang_google_grpc//connectivity:go_default_library", "@org_golang_google_grpc//grpclog:go_default_library", - "@org_golang_google_grpc//resolver:go_default_library", "@org_golang_google_protobuf//encoding/protojson:go_default_library", ], ) @@ -25,9 +25,9 @@ go_test( srcs = ["gcp_balancer_test.go"], embed = [":balancer"], deps = [ + "//go/internal/balancer", + "//go/internal/resolver", "@com_github_pborman_uuid//:go_default_library", - "@org_golang_google_grpc//balancer:go_default_library", "@org_golang_google_grpc//connectivity:go_default_library", - "@org_golang_google_grpc//resolver:go_default_library", ], ) diff --git a/go/pkg/balancer/gcp_balancer.go b/go/pkg/balancer/gcp_balancer.go index 7d03801ba..7b6162df5 100644 --- a/go/pkg/balancer/gcp_balancer.go +++ b/go/pkg/balancer/gcp_balancer.go @@ -5,11 +5,11 @@ import ( "sync" "sync/atomic" - "google.golang.org/grpc/balancer" + "github.com/bazelbuild/remote-apis-sdks/go/internal/balancer" + "github.com/bazelbuild/remote-apis-sdks/go/internal/resolver" "google.golang.org/grpc/connectivity" "google.golang.org/grpc/grpclog" - "google.golang.org/grpc/resolver" ) const ( diff --git a/go/pkg/balancer/gcp_balancer_test.go b/go/pkg/balancer/gcp_balancer_test.go index 4e29cb02c..ca86563b6 100644 --- a/go/pkg/balancer/gcp_balancer_test.go +++ b/go/pkg/balancer/gcp_balancer_test.go @@ -5,11 +5,11 @@ import ( "testing" "time" - "github.com/pborman/uuid" + grpcbalancer "github.com/bazelbuild/remote-apis-sdks/go/internal/balancer" + "github.com/bazelbuild/remote-apis-sdks/go/internal/resolver" - grpcbalancer "google.golang.org/grpc/balancer" + "github.com/pborman/uuid" "google.golang.org/grpc/connectivity" - "google.golang.org/grpc/resolver" ) func TestGCPBalancer_UpdatingConnectionStateIsMutuallyExclusive(t *testing.T) { diff --git a/go/pkg/balancer/gcp_picker.go b/go/pkg/balancer/gcp_picker.go index f3031e90c..6b5a5c248 100644 --- a/go/pkg/balancer/gcp_picker.go +++ b/go/pkg/balancer/gcp_picker.go @@ -7,8 +7,8 @@ import ( "strings" "sync" + "github.com/bazelbuild/remote-apis-sdks/go/internal/balancer" pb "github.com/bazelbuild/remote-apis-sdks/go/pkg/balancer/proto" - "google.golang.org/grpc/balancer" ) func newGCPPicker(readySCRefs []*subConnRef, gb *gcpBalancer) balancer.Picker {