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/*
*
* Copyright 2014, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
package grpc
import (
"encoding/binary"
"fmt"
"io"
"math"
"math/rand"
"os"
"time"
"github.com/golang/protobuf/proto"
"golang.org/x/net/context"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/metadata"
"google.golang.org/grpc/transport"
)
// Codec defines the interface gRPC uses to encode and decode messages.
type Codec interface {
// Marshal returns the wire format of v.
Marshal(v interface{}) ([]byte, error)
// Unmarshal parses the wire format into v.
Unmarshal(data []byte, v interface{}) error
// String returns the name of the Codec implementation. The returned
// string will be used as part of content type in transmission.
String() string
}
// protoCodec is a Codec implemetation with protobuf. It is the default codec for gRPC.
type protoCodec struct{}
func (protoCodec) Marshal(v interface{}) ([]byte, error) {
return proto.Marshal(v.(proto.Message))
}
func (protoCodec) Unmarshal(data []byte, v interface{}) error {
return proto.Unmarshal(data, v.(proto.Message))
}
func (protoCodec) String() string {
return "proto"
}
// CallOption configures a Call before it starts or extracts information from
// a Call after it completes.
type CallOption interface {
// before is called before the call is sent to any server. If before
// returns a non-nil error, the RPC fails with that error.
before(*callInfo) error
// after is called after the call has completed. after cannot return an
// error, so any failures should be reported via output parameters.
after(*callInfo)
}
type beforeCall func(c *callInfo) error
func (o beforeCall) before(c *callInfo) error { return o(c) }
func (o beforeCall) after(c *callInfo) {}
type afterCall func(c *callInfo)
func (o afterCall) before(c *callInfo) error { return nil }
func (o afterCall) after(c *callInfo) { o(c) }
// Header returns a CallOptions that retrieves the header metadata
// for a unary RPC.
func Header(md *metadata.MD) CallOption {
return afterCall(func(c *callInfo) {
*md = c.headerMD
})
}
// Trailer returns a CallOptions that retrieves the trailer metadata
// for a unary RPC.
func Trailer(md *metadata.MD) CallOption {
return afterCall(func(c *callInfo) {
*md = c.trailerMD
})
}
// The format of the payload: compressed or not?
type payloadFormat uint8
const (
compressionNone payloadFormat = iota // no compression
compressionFlate
// More formats
)
// parser reads complelete gRPC messages from the underlying reader.
type parser struct {
s io.Reader
}
// recvMsg is to read a complete gRPC message from the stream. It is blocking if
// the message has not been complete yet. It returns the message and its type,
// EOF is returned with nil msg and 0 pf if the entire stream is done. Other
// non-nil error is returned if something is wrong on reading.
func (p *parser) recvMsg() (pf payloadFormat, msg []byte, err error) {
// The header of a gRPC message. Find more detail
// at http://www.grpc.io/docs/guides/wire.html.
var buf [5]byte
if _, err := io.ReadFull(p.s, buf[:]); err != nil {
return 0, nil, err
}
pf = payloadFormat(buf[0])
length := binary.BigEndian.Uint32(buf[1:])
if length == 0 {
return pf, nil, nil
}
msg = make([]byte, int(length))
if _, err := io.ReadFull(p.s, msg); err != nil {
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
return 0, nil, err
}
return pf, msg, nil
}
// encode serializes msg and prepends the message header. If msg is nil, it
// generates the message header of 0 message length.
func encode(c Codec, msg interface{}, pf payloadFormat) ([]byte, error) {
var b []byte
var length uint
if msg != nil {
var err error
// TODO(zhaoq): optimize to reduce memory alloc and copying.
b, err = c.Marshal(msg)
if err != nil {
return nil, err
}
length = uint(len(b))
}
if length > math.MaxUint32 {
return nil, Errorf(codes.InvalidArgument, "grpc: message too large (%d bytes)", length)
}
const (
payloadLen = 1
sizeLen = 4
)
var buf = make([]byte, payloadLen+sizeLen+len(b))
// Write payload format
buf[0] = byte(pf)
// Write length of b into buf
binary.BigEndian.PutUint32(buf[1:], uint32(length))
// Copy encoded msg to buf
copy(buf[5:], b)
return buf, nil
}
func recv(p *parser, c Codec, m interface{}) error {
pf, d, err := p.recvMsg()
if err != nil {
return err
}
switch pf {
case compressionNone:
if err := c.Unmarshal(d, m); err != nil {
if rErr, ok := err.(rpcError); ok {
return rErr
} else {
return Errorf(codes.Internal, "grpc: %v", err)
}
}
default:
return Errorf(codes.Internal, "gprc: compression is not supported yet.")
}
return nil
}
// rpcError defines the status from an RPC.
type rpcError struct {
code codes.Code
desc string
}
func (e rpcError) Error() string {
return fmt.Sprintf("rpc error: code = %d desc = %q", e.code, e.desc)
}
// Code returns the error code for err if it was produced by the rpc system.
// Otherwise, it returns codes.Unknown.
func Code(err error) codes.Code {
if err == nil {
return codes.OK
}
if e, ok := err.(rpcError); ok {
return e.code
}
return codes.Unknown
}
// ErrorDesc returns the error description of err if it was produced by the rpc system.
// Otherwise, it returns err.Error() or empty string when err is nil.
func ErrorDesc(err error) string {
if err == nil {
return ""
}
if e, ok := err.(rpcError); ok {
return e.desc
}
return err.Error()
}
// Errorf returns an error containing an error code and a description;
// Errorf returns nil if c is OK.
func Errorf(c codes.Code, format string, a ...interface{}) error {
if c == codes.OK {
return nil
}
return rpcError{
code: c,
desc: fmt.Sprintf(format, a...),
}
}
// toRPCErr converts an error into a rpcError.
func toRPCErr(err error) error {
switch e := err.(type) {
case rpcError:
return err
case transport.StreamError:
return rpcError{
code: e.Code,
desc: e.Desc,
}
case transport.ConnectionError:
return rpcError{
code: codes.Internal,
desc: e.Desc,
}
}
return Errorf(codes.Unknown, "%v", err)
}
// convertCode converts a standard Go error into its canonical code. Note that
// this is only used to translate the error returned by the server applications.
func convertCode(err error) codes.Code {
switch err {
case nil:
return codes.OK
case io.EOF:
return codes.OutOfRange
case io.ErrClosedPipe, io.ErrNoProgress, io.ErrShortBuffer, io.ErrShortWrite, io.ErrUnexpectedEOF:
return codes.FailedPrecondition
case os.ErrInvalid:
return codes.InvalidArgument
case context.Canceled:
return codes.Canceled
case context.DeadlineExceeded:
return codes.DeadlineExceeded
}
switch {
case os.IsExist(err):
return codes.AlreadyExists
case os.IsNotExist(err):
return codes.NotFound
case os.IsPermission(err):
return codes.PermissionDenied
}
return codes.Unknown
}
const (
// how long to wait after the first failure before retrying
baseDelay = 1.0 * time.Second
// upper bound of backoff delay
maxDelay = 120 * time.Second
// backoff increases by this factor on each retry
backoffFactor = 1.6
// backoff is randomized downwards by this factor
backoffJitter = 0.2
)
func backoff(retries int) (t time.Duration) {
if retries == 0 {
return baseDelay
}
backoff, max := float64(baseDelay), float64(maxDelay)
for backoff < max && retries > 0 {
backoff *= backoffFactor
retries--
}
if backoff > max {
backoff = max
}
// Randomize backoff delays so that if a cluster of requests start at
// the same time, they won't operate in lockstep.
backoff *= 1 + backoffJitter*(rand.Float64()*2-1)
if backoff < 0 {
return 0
}
return time.Duration(backoff)
}