resolver

Documentation

Overview

Package resolver provides internal resolver-related functionality.

Index

• func SetConfigSelector(state resolver.State, cs ConfigSelector) resolver.State
• type ClientInterceptor
• type ClientStream
• type ConfigSelector
  • func GetConfigSelector(state resolver.State) ConfigSelector
• type RPCConfig
• type RPCInfo
• type SafeConfigSelector
  • func (scs *SafeConfigSelector) SelectConfig(r RPCInfo) (*RPCConfig, error)
  • func (scs *SafeConfigSelector) UpdateConfigSelector(cs ConfigSelector)
• type ServerInterceptor

Functions

func SetConfigSelector

func SetConfigSelector(state resolver.State, cs ConfigSelector) resolver.State

SetConfigSelector sets the config selector in state and returns the new state.

Types

type ClientInterceptor

type ClientInterceptor interface {
	// NewStream produces a ClientStream for an RPC which may optionally use
	// the provided function to produce a stream for delegation.  Note:
	// RPCInfo.Context should not be used (will be nil).
	//
	// done is invoked when the RPC is finished using its connection, or could
	// not be assigned a connection.  RPC operations may still occur on
	// ClientStream after done is called, since the interceptor is invoked by
	// application-layer operations.  done must never be nil when called.
	NewStream(ctx context.Context, ri RPCInfo, done func(), newStream func(ctx context.Context, done func()) (ClientStream, error)) (ClientStream, error)
}

ClientInterceptor is an interceptor for gRPC client streams.

type ClientStream

type ClientStream interface {
	// Header returns the header metadata received from the server if there
	// is any. It blocks if the metadata is not ready to read.
	Header() (metadata.MD, error)
	// Trailer returns the trailer metadata from the server, if there is any.
	// It must only be called after stream.CloseAndRecv has returned, or
	// stream.Recv has returned a non-nil error (including io.EOF).
	Trailer() metadata.MD
	// CloseSend closes the send direction of the stream. It closes the stream
	// when non-nil error is met. It is also not safe to call CloseSend
	// concurrently with SendMsg.
	CloseSend() error
	// Context returns the context for this stream.
	//
	// It should not be called until after Header or RecvMsg has returned. Once
	// called, subsequent client-side retries are disabled.
	Context() context.Context
	// SendMsg is generally called by generated code. On error, SendMsg aborts
	// the stream. If the error was generated by the client, the status is
	// returned directly; otherwise, io.EOF is returned and the status of
	// the stream may be discovered using RecvMsg.
	//
	// SendMsg blocks until:
	//   - There is sufficient flow control to schedule m with the transport, or
	//   - The stream is done, or
	//   - The stream breaks.
	//
	// SendMsg does not wait until the message is received by the server. An
	// untimely stream closure may result in lost messages. To ensure delivery,
	// users should ensure the RPC completed successfully using RecvMsg.
	//
	// It is safe to have a goroutine calling SendMsg and another goroutine
	// calling RecvMsg on the same stream at the same time, but it is not safe
	// to call SendMsg on the same stream in different goroutines. It is also
	// not safe to call CloseSend concurrently with SendMsg.
	SendMsg(m interface{}) error
	// RecvMsg blocks until it receives a message into m or the stream is
	// done. It returns io.EOF when the stream completes successfully. On
	// any other error, the stream is aborted and the error contains the RPC
	// status.
	//
	// It is safe to have a goroutine calling SendMsg and another goroutine
	// calling RecvMsg on the same stream at the same time, but it is not
	// safe to call RecvMsg on the same stream in different goroutines.
	RecvMsg(m interface{}) error
}

ClientStream is the same as grpc.ClientStream, but defined here for circular dependency reasons.

type ConfigSelector

type ConfigSelector interface {
	// Selects the configuration for the RPC, or terminates it using the error.
	// This error will be converted by the gRPC library to a status error with
	// code UNKNOWN if it is not returned as a status error.
	SelectConfig(RPCInfo) (*RPCConfig, error)
}

ConfigSelector controls what configuration to use for every RPC.

func GetConfigSelector

func GetConfigSelector(state resolver.State) ConfigSelector

GetConfigSelector retrieves the config selector from state, if present, and returns it or nil if absent.

type RPCConfig

type RPCConfig struct {
	// The context to use for the remainder of the RPC; can pass info to LB
	// policy or affect timeout or metadata.
	Context      context.Context
	MethodConfig serviceconfig.MethodConfig // configuration to use for this RPC
	OnCommitted  func()                     // Called when the RPC has been committed (retries no longer possible)
	Interceptor  ClientInterceptor
}

RPCConfig describes the configuration to use for each RPC.

type RPCInfo

type RPCInfo struct {
	// Context is the user's context for the RPC and contains headers and
	// application timeout.  It is passed for interception purposes and for
	// efficiency reasons.  SelectConfig should not be blocking.
	Context context.Context
	Method  string // i.e. "/Service/Method"
}

RPCInfo contains RPC information needed by a ConfigSelector.

type SafeConfigSelector

type SafeConfigSelector struct {
	// contains filtered or unexported fields
}

SafeConfigSelector allows for safe switching of ConfigSelector implementations such that previous values are guaranteed to not be in use when UpdateConfigSelector returns.

func (*SafeConfigSelector) SelectConfig

func (scs *SafeConfigSelector) SelectConfig(r RPCInfo) (*RPCConfig, error)

SelectConfig defers to the current ConfigSelector in scs.

func (*SafeConfigSelector) UpdateConfigSelector

func (scs *SafeConfigSelector) UpdateConfigSelector(cs ConfigSelector)

UpdateConfigSelector swaps to the provided ConfigSelector and blocks until all uses of the previous ConfigSelector have completed.

type ServerInterceptor

type ServerInterceptor interface {
	// AllowRPC checks if an incoming RPC is allowed to proceed based on
	// information about connection RPC was received on, and HTTP Headers. This
	// information will be piped into context.
	AllowRPC(ctx context.Context) error // TODO: Make this a real interceptor for filters such as rate limiting.
}

ServerInterceptor is an interceptor for incoming RPC's on gRPC server side.