306 lines
8.5 KiB
Go
306 lines
8.5 KiB
Go
/*
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*
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* Copyright 2014, Google Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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* * Neither the name of Google Inc. nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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package grpc
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"io"
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"math/rand"
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"os"
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"time"
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"github.com/golang/protobuf/proto"
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"golang.org/x/net/context"
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"google.golang.org/grpc/codes"
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"google.golang.org/grpc/metadata"
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"google.golang.org/grpc/transport"
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)
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// Codec defines the interface gRPC uses to encode and decode messages.
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type Codec interface {
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// Marshal returns the wire format of v.
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Marshal(v interface{}) ([]byte, error)
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// Unmarshal parses the wire format into v.
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Unmarshal(data []byte, v interface{}) error
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// String returns the name of the Codec implementation. The returned
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// string will be used as part of content type in transmission.
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String() string
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}
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// protoCodec is a Codec implemetation with protobuf. It is the default codec for gRPC.
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type protoCodec struct{}
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func (protoCodec) Marshal(v interface{}) ([]byte, error) {
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return proto.Marshal(v.(proto.Message))
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}
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func (protoCodec) Unmarshal(data []byte, v interface{}) error {
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return proto.Unmarshal(data, v.(proto.Message))
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}
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func (protoCodec) String() string {
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return "proto"
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}
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// CallOption configures a Call before it starts or extracts information from
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// a Call after it completes.
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type CallOption interface {
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// before is called before the call is sent to any server. If before
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// returns a non-nil error, the RPC fails with that error.
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before(*callInfo) error
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// after is called after the call has completed. after cannot return an
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// error, so any failures should be reported via output parameters.
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after(*callInfo)
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}
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type beforeCall func(c *callInfo) error
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func (o beforeCall) before(c *callInfo) error { return o(c) }
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func (o beforeCall) after(c *callInfo) {}
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type afterCall func(c *callInfo)
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func (o afterCall) before(c *callInfo) error { return nil }
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func (o afterCall) after(c *callInfo) { o(c) }
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// Header returns a CallOptions that retrieves the header metadata
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// for a unary RPC.
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func Header(md *metadata.MD) CallOption {
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return afterCall(func(c *callInfo) {
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*md = c.headerMD
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})
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}
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// Trailer returns a CallOptions that retrieves the trailer metadata
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// for a unary RPC.
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func Trailer(md *metadata.MD) CallOption {
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return afterCall(func(c *callInfo) {
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*md = c.trailerMD
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})
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}
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// The format of the payload: compressed or not?
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type payloadFormat uint8
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const (
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compressionNone payloadFormat = iota // no compression
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compressionFlate
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// More formats
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)
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// parser reads complelete gRPC messages from the underlying reader.
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type parser struct {
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s io.Reader
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}
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// msgFixedHeader defines the header of a gRPC message (go/grpc-wirefmt).
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type msgFixedHeader struct {
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T payloadFormat
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Length uint32
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}
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// recvMsg is to read a complete gRPC message from the stream. It is blocking if
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// the message has not been complete yet. It returns the message and its type,
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// EOF is returned with nil msg and 0 pf if the entire stream is done. Other
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// non-nil error is returned if something is wrong on reading.
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func (p *parser) recvMsg() (pf payloadFormat, msg []byte, err error) {
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var hdr msgFixedHeader
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if err := binary.Read(p.s, binary.BigEndian, &hdr); err != nil {
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return 0, nil, err
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}
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if hdr.Length == 0 {
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return hdr.T, nil, nil
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}
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msg = make([]byte, int(hdr.Length))
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if _, err := io.ReadFull(p.s, msg); err != nil {
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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}
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return 0, nil, err
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}
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return hdr.T, msg, nil
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}
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// encode serializes msg and prepends the message header. If msg is nil, it
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// generates the message header of 0 message length.
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func encode(c Codec, msg interface{}, pf payloadFormat) ([]byte, error) {
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var buf bytes.Buffer
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// Write message fixed header.
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buf.WriteByte(uint8(pf))
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var b []byte
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var length uint32
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if msg != nil {
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var err error
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// TODO(zhaoq): optimize to reduce memory alloc and copying.
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b, err = c.Marshal(msg)
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if err != nil {
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return nil, err
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}
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length = uint32(len(b))
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}
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var szHdr [4]byte
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binary.BigEndian.PutUint32(szHdr[:], length)
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buf.Write(szHdr[:])
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buf.Write(b)
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return buf.Bytes(), nil
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}
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func recv(p *parser, c Codec, m interface{}) error {
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pf, d, err := p.recvMsg()
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if err != nil {
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return err
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}
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switch pf {
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case compressionNone:
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if err := c.Unmarshal(d, m); err != nil {
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return Errorf(codes.Internal, "grpc: %v", err)
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}
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default:
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return Errorf(codes.Internal, "gprc: compression is not supported yet.")
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}
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return nil
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}
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// rpcError defines the status from an RPC.
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type rpcError struct {
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code codes.Code
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desc string
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}
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func (e rpcError) Error() string {
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return fmt.Sprintf("rpc error: code = %d desc = %q", e.code, e.desc)
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}
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// Code returns the error code for err if it was produced by the rpc system.
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// Otherwise, it returns codes.Unknown.
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func Code(err error) codes.Code {
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if err == nil {
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return codes.OK
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}
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if e, ok := err.(rpcError); ok {
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return e.code
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}
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return codes.Unknown
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}
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// Errorf returns an error containing an error code and a description;
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// Errorf returns nil if c is OK.
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func Errorf(c codes.Code, format string, a ...interface{}) error {
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if c == codes.OK {
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return nil
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}
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return rpcError{
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code: c,
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desc: fmt.Sprintf(format, a...),
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}
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}
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// toRPCErr converts an error into a rpcError.
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func toRPCErr(err error) error {
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switch e := err.(type) {
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case transport.StreamError:
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return rpcError{
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code: e.Code,
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desc: e.Desc,
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}
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case transport.ConnectionError:
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return rpcError{
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code: codes.Internal,
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desc: e.Desc,
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}
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}
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return Errorf(codes.Unknown, "%v", err)
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}
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// convertCode converts a standard Go error into its canonical code. Note that
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// this is only used to translate the error returned by the server applications.
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func convertCode(err error) codes.Code {
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switch err {
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case nil:
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return codes.OK
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case io.EOF:
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return codes.OutOfRange
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case io.ErrClosedPipe, io.ErrNoProgress, io.ErrShortBuffer, io.ErrShortWrite, io.ErrUnexpectedEOF:
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return codes.FailedPrecondition
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case os.ErrInvalid:
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return codes.InvalidArgument
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case context.Canceled:
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return codes.Canceled
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case context.DeadlineExceeded:
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return codes.DeadlineExceeded
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}
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switch {
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case os.IsExist(err):
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return codes.AlreadyExists
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case os.IsNotExist(err):
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return codes.NotFound
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case os.IsPermission(err):
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return codes.PermissionDenied
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}
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return codes.Unknown
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}
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const (
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// how long to wait after the first failure before retrying
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baseDelay = 1.0 * time.Second
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// upper bound on backoff delay
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maxDelay = 120 * time.Second
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backoffFactor = 2.0 // backoff increases by this factor on each retry
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backoffRange = 0.4 // backoff is randomized downwards by this factor
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)
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// backoff returns a value in [0, maxDelay] that increases exponentially with
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// retries, starting from baseDelay.
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func backoff(retries int) time.Duration {
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backoff, max := float64(baseDelay), float64(maxDelay)
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for backoff < max && retries > 0 {
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backoff = backoff * backoffFactor
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retries--
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}
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if backoff > max {
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backoff = max
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}
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// Randomize backoff delays so that if a cluster of requests start at
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// the same time, they won't operate in lockstep. We just subtract up
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// to 40% so that we obey maxDelay.
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backoff -= backoff * backoffRange * rand.Float64()
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if backoff < 0 {
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return 0
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}
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return time.Duration(backoff)
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}
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