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clientconn.go
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clientconn.go
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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 (
"errors"
"fmt"
"net"
"strings"
"sync"
"time"
"golang.org/x/net/context"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/grpclog"
"google.golang.org/grpc/transport"
)
var (
// ErrUnspecTarget indicates that the target address is unspecified.
ErrUnspecTarget = errors.New("grpc: target is unspecified")
// ErrNoTransportSecurity indicates that there is no transport security
// being set for ClientConn. Users should either set one or explicityly
// call WithInsecure DialOption to disable security.
ErrNoTransportSecurity = errors.New("grpc: no transport security set (use grpc.WithInsecure() explicitly or set credentials)")
// ErrCredentialsMisuse indicates that users want to transmit security infomation
// (e.g., oauth2 token) which requires secure connection on an insecure
// connection.
ErrCredentialsMisuse = errors.New("grpc: the credentials require transport level security (use grpc.WithTransportAuthenticator() to set)")
// ErrClientConnClosing indicates that the operation is illegal because
// the session is closing.
ErrClientConnClosing = errors.New("grpc: the client connection is closing")
// ErrClientConnTimeout indicates that the connection could not be
// established or re-established within the specified timeout.
ErrClientConnTimeout = errors.New("grpc: timed out trying to connect")
// minimum time to give a connection to complete
minConnectTimeout = 20 * time.Second
)
// dialOptions configure a Dial call. dialOptions are set by the DialOption
// values passed to Dial.
type dialOptions struct {
codec Codec
block bool
insecure bool
copts transport.ConnectOptions
}
// DialOption configures how we set up the connection.
type DialOption func(*dialOptions)
// WithCodec returns a DialOption which sets a codec for message marshaling and unmarshaling.
func WithCodec(c Codec) DialOption {
return func(o *dialOptions) {
o.codec = c
}
}
// WithBlock returns a DialOption which makes caller of Dial blocks until the underlying
// connection is up. Without this, Dial returns immediately and connecting the server
// happens in background.
func WithBlock() DialOption {
return func(o *dialOptions) {
o.block = true
}
}
func WithInsecure() DialOption {
return func(o *dialOptions) {
o.insecure = true
}
}
// WithTransportCredentials returns a DialOption which configures a
// connection level security credentials (e.g., TLS/SSL).
func WithTransportCredentials(creds credentials.TransportAuthenticator) DialOption {
return func(o *dialOptions) {
o.copts.AuthOptions = append(o.copts.AuthOptions, creds)
}
}
// WithPerRPCCredentials returns a DialOption which sets
// credentials which will place auth state on each outbound RPC.
func WithPerRPCCredentials(creds credentials.Credentials) DialOption {
return func(o *dialOptions) {
o.copts.AuthOptions = append(o.copts.AuthOptions, creds)
}
}
// WithTimeout returns a DialOption that configures a timeout for dialing a client connection.
func WithTimeout(d time.Duration) DialOption {
return func(o *dialOptions) {
o.copts.Timeout = d
}
}
// WithDialer returns a DialOption that specifies a function to use for dialing network addresses.
func WithDialer(f func(addr string, timeout time.Duration) (net.Conn, error)) DialOption {
return func(o *dialOptions) {
o.copts.Dialer = f
}
}
// WithUserAgent returns a DialOption that specifies a user agent string for all the RPCs.
func WithUserAgent(s string) DialOption {
return func(o *dialOptions) {
o.copts.UserAgent = s
}
}
// Dial creates a client connection the given target.
func Dial(target string, opts ...DialOption) (*ClientConn, error) {
if target == "" {
return nil, ErrUnspecTarget
}
cc := &ClientConn{
target: target,
shutdownChan: make(chan struct{}),
}
for _, opt := range opts {
opt(&cc.dopts)
}
if !cc.dopts.insecure {
var ok bool
for _, c := range cc.dopts.copts.AuthOptions {
if _, ok := c.(credentials.TransportAuthenticator); !ok {
continue
}
ok = true
}
if !ok {
return nil, ErrNoTransportSecurity
}
} else {
for _, c := range cc.dopts.copts.AuthOptions {
if c.RequireTransportSecurity() {
return nil, ErrCredentialsMisuse
}
}
}
colonPos := strings.LastIndex(target, ":")
if colonPos == -1 {
colonPos = len(target)
}
cc.authority = target[:colonPos]
if cc.dopts.codec == nil {
// Set the default codec.
cc.dopts.codec = protoCodec{}
}
cc.stateCV = sync.NewCond(&cc.mu)
if cc.dopts.block {
if err := cc.resetTransport(false); err != nil {
cc.Close()
return nil, err
}
// Start to monitor the error status of transport.
go cc.transportMonitor()
} else {
// Start a goroutine connecting to the server asynchronously.
go func() {
if err := cc.resetTransport(false); err != nil {
grpclog.Printf("Failed to dial %s: %v; please retry.", target, err)
cc.Close()
return
}
go cc.transportMonitor()
}()
}
return cc, nil
}
// ConnectivityState indicates the state of a client connection.
type ConnectivityState int
const (
// Idle indicates the ClientConn is idle.
Idle ConnectivityState = iota
// Connecting indicates the ClienConn is connecting.
Connecting
// Ready indicates the ClientConn is ready for work.
Ready
// TransientFailure indicates the ClientConn has seen a failure but expects to recover.
TransientFailure
// Shutdown indicates the ClientConn has started shutting down.
Shutdown
)
func (s ConnectivityState) String() string {
switch s {
case Idle:
return "IDLE"
case Connecting:
return "CONNECTING"
case Ready:
return "READY"
case TransientFailure:
return "TRANSIENT_FAILURE"
case Shutdown:
return "SHUTDOWN"
default:
panic(fmt.Sprintf("unknown connectivity state: %d", s))
}
}
// ClientConn represents a client connection to an RPC service.
type ClientConn struct {
target string
authority string
dopts dialOptions
shutdownChan chan struct{}
mu sync.Mutex
state ConnectivityState
stateCV *sync.Cond
// ready is closed and becomes nil when a new transport is up or failed
// due to timeout.
ready chan struct{}
transport transport.ClientTransport
}
// State returns the connectivity state of the ClientConn
func (cc *ClientConn) State() ConnectivityState {
cc.mu.Lock()
defer cc.mu.Unlock()
return cc.state
}
// WaitForStateChange blocks until the state changes to something other than the sourceState
// or timeout fires. It returns false if timeout fires and true otherwise.
func (cc *ClientConn) WaitForStateChange(timeout time.Duration, sourceState ConnectivityState) bool {
start := time.Now()
cc.mu.Lock()
defer cc.mu.Unlock()
if sourceState != cc.state {
return true
}
expired := timeout <= time.Since(start)
if expired {
return false
}
done := make(chan struct{})
go func() {
select {
case <-time.After(timeout - time.Since(start)):
cc.mu.Lock()
expired = true
cc.stateCV.Broadcast()
cc.mu.Unlock()
case <-done:
}
}()
defer close(done)
for sourceState == cc.state {
cc.stateCV.Wait()
if expired {
return false
}
}
return true
}
func (cc *ClientConn) resetTransport(closeTransport bool) error {
var retries int
start := time.Now()
for {
cc.mu.Lock()
if cc.state == Shutdown {
cc.mu.Unlock()
return ErrClientConnClosing
}
cc.state = Connecting
cc.stateCV.Broadcast()
cc.mu.Unlock()
if closeTransport {
cc.transport.Close()
}
// Adjust timeout for the current try.
copts := cc.dopts.copts
if copts.Timeout < 0 {
cc.Close()
return ErrClientConnTimeout
}
if copts.Timeout > 0 {
copts.Timeout -= time.Since(start)
if copts.Timeout <= 0 {
cc.Close()
return ErrClientConnTimeout
}
}
sleepTime := backoff(retries)
timeout := sleepTime
if timeout < minConnectTimeout {
timeout = minConnectTimeout
}
if copts.Timeout == 0 || copts.Timeout > timeout {
copts.Timeout = timeout
}
connectTime := time.Now()
newTransport, err := transport.NewClientTransport(cc.target, &copts)
if err != nil {
cc.mu.Lock()
cc.state = TransientFailure
cc.stateCV.Broadcast()
cc.mu.Unlock()
sleepTime -= time.Since(connectTime)
if sleepTime < 0 {
sleepTime = 0
}
// Fail early before falling into sleep.
if cc.dopts.copts.Timeout > 0 && cc.dopts.copts.Timeout < sleepTime+time.Since(start) {
cc.Close()
return ErrClientConnTimeout
}
closeTransport = false
time.Sleep(sleepTime)
retries++
grpclog.Printf("grpc: ClientConn.resetTransport failed to create client transport: %v; Reconnecting to %q", err, cc.target)
continue
}
cc.mu.Lock()
if cc.state == Shutdown {
// cc.Close() has been invoked.
cc.mu.Unlock()
newTransport.Close()
return ErrClientConnClosing
}
cc.state = Ready
cc.stateCV.Broadcast()
cc.transport = newTransport
if cc.ready != nil {
close(cc.ready)
cc.ready = nil
}
cc.mu.Unlock()
return nil
}
}
// Run in a goroutine to track the error in transport and create the
// new transport if an error happens. It returns when the channel is closing.
func (cc *ClientConn) transportMonitor() {
for {
select {
// shutdownChan is needed to detect the teardown when
// the ClientConn is idle (i.e., no RPC in flight).
case <-cc.shutdownChan:
return
case <-cc.transport.Error():
cc.mu.Lock()
cc.state = TransientFailure
cc.stateCV.Broadcast()
cc.mu.Unlock()
if err := cc.resetTransport(true); err != nil {
// The ClientConn is closing.
grpclog.Printf("grpc: ClientConn.transportMonitor exits due to: %v", err)
return
}
continue
}
}
}
// When wait returns, either the new transport is up or ClientConn is
// closing.
func (cc *ClientConn) wait(ctx context.Context) (transport.ClientTransport, error) {
for {
cc.mu.Lock()
switch {
case cc.state == Shutdown:
cc.mu.Unlock()
return nil, ErrClientConnClosing
case cc.state == Ready:
cc.mu.Unlock()
return cc.transport, nil
default:
ready := cc.ready
if ready == nil {
ready = make(chan struct{})
cc.ready = ready
}
cc.mu.Unlock()
select {
case <-ctx.Done():
return nil, transport.ContextErr(ctx.Err())
// Wait until the new transport is ready or failed.
case <-ready:
}
}
}
}
// Close starts to tear down the ClientConn. Returns ErrClientConnClosing if
// it has been closed (mostly due to dial time-out).
// TODO(zhaoq): Make this synchronous to avoid unbounded memory consumption in
// some edge cases (e.g., the caller opens and closes many ClientConn's in a
// tight loop.
func (cc *ClientConn) Close() error {
cc.mu.Lock()
defer cc.mu.Unlock()
if cc.state == Shutdown {
return ErrClientConnClosing
}
cc.state = Shutdown
cc.stateCV.Broadcast()
if cc.ready != nil {
close(cc.ready)
cc.ready = nil
}
if cc.transport != nil {
cc.transport.Close()
}
if cc.shutdownChan != nil {
close(cc.shutdownChan)
}
return nil
}