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/*
*
* Copyright 2014 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 grpc
import (
"context"
"errors"
"fmt"
"math"
"net"
"reflect"
"strings"
"sync"
"sync/atomic"
"time"
"google.golang.org/grpc/balancer"
_ "google.golang.org/grpc/balancer/roundrobin" // To register roundrobin.
"google.golang.org/grpc/codes"
"google.golang.org/grpc/connectivity"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/grpclog"
"google.golang.org/grpc/internal/backoff"
"google.golang.org/grpc/internal/channelz"
"google.golang.org/grpc/internal/grpcsync"
"google.golang.org/grpc/internal/transport"
"google.golang.org/grpc/keepalive"
"google.golang.org/grpc/resolver"
_ "google.golang.org/grpc/resolver/dns" // To register dns resolver.
_ "google.golang.org/grpc/resolver/passthrough" // To register passthrough resolver.
"google.golang.org/grpc/serviceconfig"
"google.golang.org/grpc/status"
)
const (
// minimum time to give a connection to complete
minConnectTimeout = 20 * time.Second
// must match grpclbName in grpclb/grpclb.go
grpclbName = "grpclb"
)
var (
// ErrClientConnClosing indicates that the operation is illegal because
// the ClientConn is closing.
//
// Deprecated: this error should not be relied upon by users; use the status
// code of Canceled instead.
ErrClientConnClosing = status.Error(codes.Canceled, "grpc: the client connection is closing")
// errConnDrain indicates that the connection starts to be drained and does not accept any new RPCs.
errConnDrain = errors.New("grpc: the connection is drained")
// errConnClosing indicates that the connection is closing.
errConnClosing = errors.New("grpc: the connection is closing")
// errBalancerClosed indicates that the balancer is closed.
errBalancerClosed = errors.New("grpc: balancer is closed")
// invalidDefaultServiceConfigErrPrefix is used to prefix the json parsing error for the default
// service config.
invalidDefaultServiceConfigErrPrefix = "grpc: the provided default service config is invalid"
)
// The following errors are returned from Dial and DialContext
var (
// errNoTransportSecurity indicates that there is no transport security
// being set for ClientConn. Users should either set one or explicitly
// call WithInsecure DialOption to disable security.
errNoTransportSecurity = errors.New("grpc: no transport security set (use grpc.WithInsecure() explicitly or set credentials)")
// errTransportCredsAndBundle indicates that creds bundle is used together
// with other individual Transport Credentials.
errTransportCredsAndBundle = errors.New("grpc: credentials.Bundle may not be used with individual TransportCredentials")
// errTransportCredentialsMissing indicates that users want to transmit security
// information (e.g., OAuth2 token) which requires secure connection on an insecure
// connection.
errTransportCredentialsMissing = errors.New("grpc: the credentials require transport level security (use grpc.WithTransportCredentials() to set)")
// errCredentialsConflict indicates that grpc.WithTransportCredentials()
// and grpc.WithInsecure() are both called for a connection.
errCredentialsConflict = errors.New("grpc: transport credentials are set for an insecure connection (grpc.WithTransportCredentials() and grpc.WithInsecure() are both called)")
)
const (
defaultClientMaxReceiveMessageSize = 1024 * 1024 * 4
defaultClientMaxSendMessageSize = math.MaxInt32
// http2IOBufSize specifies the buffer size for sending frames.
defaultWriteBufSize = 32 * 1024
defaultReadBufSize = 32 * 1024
)
// Dial creates a client connection to the given target.
func Dial(target string, opts ...DialOption) (*ClientConn, error) {
return DialContext(context.Background(), target, opts...)
}
// DialContext creates a client connection to the given target. By default, it's
// a non-blocking dial (the function won't wait for connections to be
// established, and connecting happens in the background). To make it a blocking
// dial, use WithBlock() dial option.
//
// In the non-blocking case, the ctx does not act against the connection. It
// only controls the setup steps.
//
// In the blocking case, ctx can be used to cancel or expire the pending
// connection. Once this function returns, the cancellation and expiration of
// ctx will be noop. Users should call ClientConn.Close to terminate all the
// pending operations after this function returns.
//
// The target name syntax is defined in
// https://github.com/grpc/grpc/blob/master/doc/naming.md.
// e.g. to use dns resolver, a "dns:///" prefix should be applied to the target.
func DialContext(ctx context.Context, target string, opts ...DialOption) (conn *ClientConn, err error) {
cc := &ClientConn{
target: target,
csMgr: &connectivityStateManager{},
conns: make(map[*addrConn]struct{}),
dopts: defaultDialOptions(),
blockingpicker: newPickerWrapper(),
czData: new(channelzData),
firstResolveEvent: grpcsync.NewEvent(),
}
cc.retryThrottler.Store((*retryThrottler)(nil))
cc.ctx, cc.cancel = context.WithCancel(context.Background())
for _, opt := range opts {
opt.apply(&cc.dopts)
}
chainUnaryClientInterceptors(cc)
chainStreamClientInterceptors(cc)
defer func() {
if err != nil {
cc.Close()
}
}()
if channelz.IsOn() {
if cc.dopts.channelzParentID != 0 {
cc.channelzID = channelz.RegisterChannel(&channelzChannel{cc}, cc.dopts.channelzParentID, target)
channelz.AddTraceEvent(cc.channelzID, &channelz.TraceEventDesc{
Desc: "Channel Created",
Severity: channelz.CtINFO,
Parent: &channelz.TraceEventDesc{
Desc: fmt.Sprintf("Nested Channel(id:%d) created", cc.channelzID),
Severity: channelz.CtINFO,
},
})
} else {
cc.channelzID = channelz.RegisterChannel(&channelzChannel{cc}, 0, target)
channelz.AddTraceEvent(cc.channelzID, &channelz.TraceEventDesc{
Desc: "Channel Created",
Severity: channelz.CtINFO,
})
}
cc.csMgr.channelzID = cc.channelzID
}
if !cc.dopts.insecure {
if cc.dopts.copts.TransportCredentials == nil && cc.dopts.copts.CredsBundle == nil {
return nil, errNoTransportSecurity
}
if cc.dopts.copts.TransportCredentials != nil && cc.dopts.copts.CredsBundle != nil {
return nil, errTransportCredsAndBundle
}
} else {
if cc.dopts.copts.TransportCredentials != nil || cc.dopts.copts.CredsBundle != nil {
return nil, errCredentialsConflict
}
for _, cd := range cc.dopts.copts.PerRPCCredentials {
if cd.RequireTransportSecurity() {
return nil, errTransportCredentialsMissing
}
}
}
if cc.dopts.defaultServiceConfigRawJSON != nil {
sc, err := parseServiceConfig(*cc.dopts.defaultServiceConfigRawJSON)
if err != nil {
return nil, fmt.Errorf("%s: %v", invalidDefaultServiceConfigErrPrefix, err)
}
cc.dopts.defaultServiceConfig = sc
}
cc.mkp = cc.dopts.copts.KeepaliveParams
if cc.dopts.copts.Dialer == nil {
cc.dopts.copts.Dialer = newProxyDialer(
func(ctx context.Context, addr string) (net.Conn, error) {
network, addr := parseDialTarget(addr)
return (&net.Dialer{}).DialContext(ctx, network, addr)
},
)
}
if cc.dopts.copts.UserAgent != "" {
cc.dopts.copts.UserAgent += " " + grpcUA
} else {
cc.dopts.copts.UserAgent = grpcUA
}
if cc.dopts.timeout > 0 {
var cancel context.CancelFunc
ctx, cancel = context.WithTimeout(ctx, cc.dopts.timeout)
defer cancel()
}
defer func() {
select {
case <-ctx.Done():
conn, err = nil, ctx.Err()
default:
}
}()
scSet := false
if cc.dopts.scChan != nil {
// Try to get an initial service config.
select {
case sc, ok := <-cc.dopts.scChan:
if ok {
cc.sc = &sc
scSet = true
}
default:
}
}
if cc.dopts.bs == nil {
cc.dopts.bs = backoff.Exponential{
MaxDelay: DefaultBackoffConfig.MaxDelay,
}
}
if cc.dopts.resolverBuilder == nil {
// Only try to parse target when resolver builder is not already set.
cc.parsedTarget = parseTarget(cc.target)
grpclog.Infof("parsed scheme: %q", cc.parsedTarget.Scheme)
cc.dopts.resolverBuilder = resolver.Get(cc.parsedTarget.Scheme)
if cc.dopts.resolverBuilder == nil {
// If resolver builder is still nil, the parsed target's scheme is
// not registered. Fallback to default resolver and set Endpoint to
// the original target.
grpclog.Infof("scheme %q not registered, fallback to default scheme", cc.parsedTarget.Scheme)
cc.parsedTarget = resolver.Target{
Scheme: resolver.GetDefaultScheme(),
Endpoint: target,
}
cc.dopts.resolverBuilder = resolver.Get(cc.parsedTarget.Scheme)
}
} else {
cc.parsedTarget = resolver.Target{Endpoint: target}
}
creds := cc.dopts.copts.TransportCredentials
if creds != nil && creds.Info().ServerName != "" {
cc.authority = creds.Info().ServerName
} else if cc.dopts.insecure && cc.dopts.authority != "" {
cc.authority = cc.dopts.authority
} else {
// Use endpoint from "scheme://authority/endpoint" as the default
// authority for ClientConn.
cc.authority = cc.parsedTarget.Endpoint
}
if cc.dopts.scChan != nil && !scSet {
// Blocking wait for the initial service config.
select {
case sc, ok := <-cc.dopts.scChan:
if ok {
cc.sc = &sc
}
case <-ctx.Done():
return nil, ctx.Err()
}
}
if cc.dopts.scChan != nil {
go cc.scWatcher()
}
var credsClone credentials.TransportCredentials
if creds := cc.dopts.copts.TransportCredentials; creds != nil {
credsClone = creds.Clone()
}
cc.balancerBuildOpts = balancer.BuildOptions{
DialCreds: credsClone,
CredsBundle: cc.dopts.copts.CredsBundle,
Dialer: cc.dopts.copts.Dialer,
ChannelzParentID: cc.channelzID,
Target: cc.parsedTarget,
}
// Build the resolver.
rWrapper, err := newCCResolverWrapper(cc)
if err != nil {
return nil, fmt.Errorf("failed to build resolver: %v", err)
}
cc.mu.Lock()
cc.resolverWrapper = rWrapper
cc.mu.Unlock()
// A blocking dial blocks until the clientConn is ready.
if cc.dopts.block {
for {
s := cc.GetState()
if s == connectivity.Ready {
break
} else if cc.dopts.copts.FailOnNonTempDialError && s == connectivity.TransientFailure {
if err = cc.blockingpicker.connectionError(); err != nil {
terr, ok := err.(interface {
Temporary() bool
})
if ok && !terr.Temporary() {
return nil, err
}
}
}
if !cc.WaitForStateChange(ctx, s) {
// ctx got timeout or canceled.
return nil, ctx.Err()
}
}
}
return cc, nil
}
// chainUnaryClientInterceptors chains all unary client interceptors into one.
func chainUnaryClientInterceptors(cc *ClientConn) {
interceptors := cc.dopts.chainUnaryInts
// Prepend dopts.unaryInt to the chaining interceptors if it exists, since unaryInt will
// be executed before any other chained interceptors.
if cc.dopts.unaryInt != nil {
interceptors = append([]UnaryClientInterceptor{cc.dopts.unaryInt}, interceptors...)
}
var chainedInt UnaryClientInterceptor
if len(interceptors) == 0 {
chainedInt = nil
} else if len(interceptors) == 1 {
chainedInt = interceptors[0]
} else {
chainedInt = func(ctx context.Context, method string, req, reply interface{}, cc *ClientConn, invoker UnaryInvoker, opts ...CallOption) error {
return interceptors[0](ctx, method, req, reply, cc, getChainUnaryInvoker(interceptors, 0, invoker), opts...)
}
}
cc.dopts.unaryInt = chainedInt
}
// getChainUnaryInvoker recursively generate the chained unary invoker.
func getChainUnaryInvoker(interceptors []UnaryClientInterceptor, curr int, finalInvoker UnaryInvoker) UnaryInvoker {
if curr == len(interceptors)-1 {
return finalInvoker
}
return func(ctx context.Context, method string, req, reply interface{}, cc *ClientConn, opts ...CallOption) error {
return interceptors[curr+1](ctx, method, req, reply, cc, getChainUnaryInvoker(interceptors, curr+1, finalInvoker), opts...)
}
}
// chainStreamClientInterceptors chains all stream client interceptors into one.
func chainStreamClientInterceptors(cc *ClientConn) {
interceptors := cc.dopts.chainStreamInts
// Prepend dopts.streamInt to the chaining interceptors if it exists, since streamInt will
// be executed before any other chained interceptors.
if cc.dopts.streamInt != nil {
interceptors = append([]StreamClientInterceptor{cc.dopts.streamInt}, interceptors...)
}
var chainedInt StreamClientInterceptor
if len(interceptors) == 0 {
chainedInt = nil
} else if len(interceptors) == 1 {
chainedInt = interceptors[0]
} else {
chainedInt = func(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, streamer Streamer, opts ...CallOption) (ClientStream, error) {
return interceptors[0](ctx, desc, cc, method, getChainStreamer(interceptors, 0, streamer), opts...)
}
}
cc.dopts.streamInt = chainedInt
}
// getChainStreamer recursively generate the chained client stream constructor.
func getChainStreamer(interceptors []StreamClientInterceptor, curr int, finalStreamer Streamer) Streamer {
if curr == len(interceptors)-1 {
return finalStreamer
}
return func(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, opts ...CallOption) (ClientStream, error) {
return interceptors[curr+1](ctx, desc, cc, method, getChainStreamer(interceptors, curr+1, finalStreamer), opts...)
}
}
// connectivityStateManager keeps the connectivity.State of ClientConn.
// This struct will eventually be exported so the balancers can access it.
type connectivityStateManager struct {
mu sync.Mutex
state connectivity.State
notifyChan chan struct{}
channelzID int64
}
// updateState updates the connectivity.State of ClientConn.
// If there's a change it notifies goroutines waiting on state change to
// happen.
func (csm *connectivityStateManager) updateState(state connectivity.State) {
csm.mu.Lock()
defer csm.mu.Unlock()
if csm.state == connectivity.Shutdown {
return
}
if csm.state == state {
return
}
csm.state = state
if channelz.IsOn() {
channelz.AddTraceEvent(csm.channelzID, &channelz.TraceEventDesc{
Desc: fmt.Sprintf("Channel Connectivity change to %v", state),
Severity: channelz.CtINFO,
})
}
if csm.notifyChan != nil {
// There are other goroutines waiting on this channel.
close(csm.notifyChan)
csm.notifyChan = nil
}
}
func (csm *connectivityStateManager) getState() connectivity.State {
csm.mu.Lock()
defer csm.mu.Unlock()
return csm.state
}
func (csm *connectivityStateManager) getNotifyChan() <-chan struct{} {
csm.mu.Lock()
defer csm.mu.Unlock()
if csm.notifyChan == nil {
csm.notifyChan = make(chan struct{})
}
return csm.notifyChan
}
// ClientConn represents a client connection to an RPC server.
type ClientConn struct {
ctx context.Context
cancel context.CancelFunc
target string
parsedTarget resolver.Target
authority string
dopts dialOptions
csMgr *connectivityStateManager
balancerBuildOpts balancer.BuildOptions
blockingpicker *pickerWrapper
mu sync.RWMutex
resolverWrapper *ccResolverWrapper
sc *ServiceConfig
conns map[*addrConn]struct{}
// Keepalive parameter can be updated if a GoAway is received.
mkp keepalive.ClientParameters
curBalancerName string
balancerWrapper *ccBalancerWrapper
retryThrottler atomic.Value
firstResolveEvent *grpcsync.Event
channelzID int64 // channelz unique identification number
czData *channelzData
}
// WaitForStateChange waits until the connectivity.State of ClientConn changes from sourceState or
// ctx expires. A true value is returned in former case and false in latter.
// This is an EXPERIMENTAL API.
func (cc *ClientConn) WaitForStateChange(ctx context.Context, sourceState connectivity.State) bool {
ch := cc.csMgr.getNotifyChan()
if cc.csMgr.getState() != sourceState {
return true
}
select {
case <-ctx.Done():
return false
case <-ch:
return true
}
}
// GetState returns the connectivity.State of ClientConn.
// This is an EXPERIMENTAL API.
func (cc *ClientConn) GetState() connectivity.State {
return cc.csMgr.getState()
}
func (cc *ClientConn) scWatcher() {
for {
select {
case sc, ok := <-cc.dopts.scChan:
if !ok {
return
}
cc.mu.Lock()
// TODO: load balance policy runtime change is ignored.
// We may revisit this decision in the future.
cc.sc = &sc
cc.mu.Unlock()
case <-cc.ctx.Done():
return
}
}
}
// waitForResolvedAddrs blocks until the resolver has provided addresses or the
// context expires. Returns nil unless the context expires first; otherwise
// returns a status error based on the context.
func (cc *ClientConn) waitForResolvedAddrs(ctx context.Context) error {
// This is on the RPC path, so we use a fast path to avoid the
// more-expensive "select" below after the resolver has returned once.
if cc.firstResolveEvent.HasFired() {
return nil
}
select {
case <-cc.firstResolveEvent.Done():
return nil
case <-ctx.Done():
return status.FromContextError(ctx.Err()).Err()
case <-cc.ctx.Done():
return ErrClientConnClosing
}
}
func (cc *ClientConn) updateResolverState(s resolver.State) error {
cc.mu.Lock()
defer cc.mu.Unlock()
// Check if the ClientConn is already closed. Some fields (e.g.
// balancerWrapper) are set to nil when closing the ClientConn, and could
// cause nil pointer panic if we don't have this check.
if cc.conns == nil {
return nil
}
if cc.dopts.disableServiceConfig || s.ServiceConfig == nil {
if cc.dopts.defaultServiceConfig != nil && cc.sc == nil {
cc.applyServiceConfig(cc.dopts.defaultServiceConfig)
}
} else if sc, ok := s.ServiceConfig.(*ServiceConfig); ok {
cc.applyServiceConfig(sc)
}
var balCfg serviceconfig.LoadBalancingConfig
if cc.dopts.balancerBuilder == nil {
// Only look at balancer types and switch balancer if balancer dial
// option is not set.
var newBalancerName string
if cc.sc != nil && cc.sc.lbConfig != nil {
newBalancerName = cc.sc.lbConfig.name
balCfg = cc.sc.lbConfig.cfg
} else {
var isGRPCLB bool
for _, a := range s.Addresses {
if a.Type == resolver.GRPCLB {
isGRPCLB = true
break
}
}
if isGRPCLB {
newBalancerName = grpclbName
} else if cc.sc != nil && cc.sc.LB != nil {
newBalancerName = *cc.sc.LB
} else {
newBalancerName = PickFirstBalancerName
}
}
cc.switchBalancer(newBalancerName)
} else if cc.balancerWrapper == nil {
// Balancer dial option was set, and this is the first time handling
// resolved addresses. Build a balancer with dopts.balancerBuilder.
cc.curBalancerName = cc.dopts.balancerBuilder.Name()
cc.balancerWrapper = newCCBalancerWrapper(cc, cc.dopts.balancerBuilder, cc.balancerBuildOpts)
}
cc.balancerWrapper.updateClientConnState(&balancer.ClientConnState{ResolverState: s, BalancerConfig: balCfg})
return nil
}
// switchBalancer starts the switching from current balancer to the balancer
// with the given name.
//
// It will NOT send the current address list to the new balancer. If needed,
// caller of this function should send address list to the new balancer after
// this function returns.
//
// Caller must hold cc.mu.
func (cc *ClientConn) switchBalancer(name string) {
if strings.EqualFold(cc.curBalancerName, name) {
return
}
grpclog.Infof("ClientConn switching balancer to %q", name)
if cc.dopts.balancerBuilder != nil {
grpclog.Infoln("ignoring balancer switching: Balancer DialOption used instead")
return
}
if cc.balancerWrapper != nil {
cc.balancerWrapper.close()
}
builder := balancer.Get(name)
if channelz.IsOn() {
if builder == nil {
channelz.AddTraceEvent(cc.channelzID, &channelz.TraceEventDesc{
Desc: fmt.Sprintf("Channel switches to new LB policy %q due to fallback from invalid balancer name", PickFirstBalancerName),
Severity: channelz.CtWarning,
})
} else {
channelz.AddTraceEvent(cc.channelzID, &channelz.TraceEventDesc{
Desc: fmt.Sprintf("Channel switches to new LB policy %q", name),
Severity: channelz.CtINFO,
})
}
}
if builder == nil {
grpclog.Infof("failed to get balancer builder for: %v, using pick_first instead", name)
builder = newPickfirstBuilder()
}
cc.curBalancerName = builder.Name()
cc.balancerWrapper = newCCBalancerWrapper(cc, builder, cc.balancerBuildOpts)
}
func (cc *ClientConn) handleSubConnStateChange(sc balancer.SubConn, s connectivity.State) {
cc.mu.Lock()
if cc.conns == nil {
cc.mu.Unlock()
return
}
// TODO(bar switching) send updates to all balancer wrappers when balancer
// gracefully switching is supported.
cc.balancerWrapper.handleSubConnStateChange(sc, s)
cc.mu.Unlock()
}
// newAddrConn creates an addrConn for addrs and adds it to cc.conns.
//
// Caller needs to make sure len(addrs) > 0.
func (cc *ClientConn) newAddrConn(addrs []resolver.Address, opts balancer.NewSubConnOptions) (*addrConn, error) {
ac := &addrConn{
cc: cc,
addrs: addrs,
scopts: opts,
dopts: cc.dopts,
czData: new(channelzData),
resetBackoff: make(chan struct{}),
}
ac.ctx, ac.cancel = context.WithCancel(cc.ctx)
// Track ac in cc. This needs to be done before any getTransport(...) is called.
cc.mu.Lock()
if cc.conns == nil {
cc.mu.Unlock()
return nil, ErrClientConnClosing
}
if channelz.IsOn() {
ac.channelzID = channelz.RegisterSubChannel(ac, cc.channelzID, "")
channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{
Desc: "Subchannel Created",
Severity: channelz.CtINFO,
Parent: &channelz.TraceEventDesc{
Desc: fmt.Sprintf("Subchannel(id:%d) created", ac.channelzID),
Severity: channelz.CtINFO,
},
})
}
cc.conns[ac] = struct{}{}
cc.mu.Unlock()
return ac, nil
}
// removeAddrConn removes the addrConn in the subConn from clientConn.
// It also tears down the ac with the given error.
func (cc *ClientConn) removeAddrConn(ac *addrConn, err error) {
cc.mu.Lock()
if cc.conns == nil {
cc.mu.Unlock()
return
}
delete(cc.conns, ac)
cc.mu.Unlock()
ac.tearDown(err)
}
func (cc *ClientConn) channelzMetric() *channelz.ChannelInternalMetric {
return &channelz.ChannelInternalMetric{
State: cc.GetState(),
Target: cc.target,
CallsStarted: atomic.LoadInt64(&cc.czData.callsStarted),
CallsSucceeded: atomic.LoadInt64(&cc.czData.callsSucceeded),
CallsFailed: atomic.LoadInt64(&cc.czData.callsFailed),
LastCallStartedTimestamp: time.Unix(0, atomic.LoadInt64(&cc.czData.lastCallStartedTime)),
}
}
// Target returns the target string of the ClientConn.
// This is an EXPERIMENTAL API.
func (cc *ClientConn) Target() string {
return cc.target
}
func (cc *ClientConn) incrCallsStarted() {
atomic.AddInt64(&cc.czData.callsStarted, 1)
atomic.StoreInt64(&cc.czData.lastCallStartedTime, time.Now().UnixNano())
}
func (cc *ClientConn) incrCallsSucceeded() {
atomic.AddInt64(&cc.czData.callsSucceeded, 1)
}
func (cc *ClientConn) incrCallsFailed() {
atomic.AddInt64(&cc.czData.callsFailed, 1)
}
// connect starts creating a transport.
// It does nothing if the ac is not IDLE.
// TODO(bar) Move this to the addrConn section.
func (ac *addrConn) connect() error {
ac.mu.Lock()
if ac.state == connectivity.Shutdown {
ac.mu.Unlock()
return errConnClosing
}
if ac.state != connectivity.Idle {
ac.mu.Unlock()
return nil
}
// Update connectivity state within the lock to prevent subsequent or
// concurrent calls from resetting the transport more than once.
ac.updateConnectivityState(connectivity.Connecting)
ac.mu.Unlock()
// Start a goroutine connecting to the server asynchronously.
go ac.resetTransport()
return nil
}
// tryUpdateAddrs tries to update ac.addrs with the new addresses list.
//
// If ac is Connecting, it returns false. The caller should tear down the ac and
// create a new one. Note that the backoff will be reset when this happens.
//
// If ac is TransientFailure, it updates ac.addrs and returns true. The updated
// addresses will be picked up by retry in the next iteration after backoff.
//
// If ac is Shutdown or Idle, it updates ac.addrs and returns true.
//
// If ac is Ready, it checks whether current connected address of ac is in the
// new addrs list.
// - If true, it updates ac.addrs and returns true. The ac will keep using
// the existing connection.
// - If false, it does nothing and returns false.
func (ac *addrConn) tryUpdateAddrs(addrs []resolver.Address) bool {
ac.mu.Lock()
defer ac.mu.Unlock()
grpclog.Infof("addrConn: tryUpdateAddrs curAddr: %v, addrs: %v", ac.curAddr, addrs)
if ac.state == connectivity.Shutdown ||
ac.state == connectivity.TransientFailure ||
ac.state == connectivity.Idle {
ac.addrs = addrs
return true
}
if ac.state == connectivity.Connecting {
return false
}
// ac.state is Ready, try to find the connected address.
var curAddrFound bool
for _, a := range addrs {
if reflect.DeepEqual(ac.curAddr, a) {
curAddrFound = true
break
}
}
grpclog.Infof("addrConn: tryUpdateAddrs curAddrFound: %v", curAddrFound)
if curAddrFound {
ac.addrs = addrs
}
return curAddrFound
}
// GetMethodConfig gets the method config of the input method.
// If there's an exact match for input method (i.e. /service/method), we return
// the corresponding MethodConfig.
// If there isn't an exact match for the input method, we look for the default config
// under the service (i.e /service/). If there is a default MethodConfig for
// the service, we return it.
// Otherwise, we return an empty MethodConfig.
func (cc *ClientConn) GetMethodConfig(method string) MethodConfig {
// TODO: Avoid the locking here.
cc.mu.RLock()
defer cc.mu.RUnlock()
if cc.sc == nil {
return MethodConfig{}
}
m, ok := cc.sc.Methods[method]
if !ok {
i := strings.LastIndex(method, "/")
m = cc.sc.Methods[method[:i+1]]
}
return m
}
func (cc *ClientConn) healthCheckConfig() *healthCheckConfig {
cc.mu.RLock()
defer cc.mu.RUnlock()
if cc.sc == nil {
return nil
}
return cc.sc.healthCheckConfig
}
func (cc *ClientConn) getTransport(ctx context.Context, failfast bool, method string) (transport.ClientTransport, func(balancer.DoneInfo), error) {
t, done, err := cc.blockingpicker.pick(ctx, failfast, balancer.PickOptions{
FullMethodName: method,
})
if err != nil {
return nil, nil, toRPCErr(err)
}
return t, done, nil
}
func (cc *ClientConn) applyServiceConfig(sc *ServiceConfig) error {
if sc == nil {
// should never reach here.
return fmt.Errorf("got nil pointer for service config")
}
cc.sc = sc
if cc.sc.retryThrottling != nil {
newThrottler := &retryThrottler{
tokens: cc.sc.retryThrottling.MaxTokens,
max: cc.sc.retryThrottling.MaxTokens,
thresh: cc.sc.retryThrottling.MaxTokens / 2,
ratio: cc.sc.retryThrottling.TokenRatio,
}
cc.retryThrottler.Store(newThrottler)
} else {
cc.retryThrottler.Store((*retryThrottler)(nil))
}
return nil
}
func (cc *ClientConn) resolveNow(o resolver.ResolveNowOption) {
cc.mu.RLock()
r := cc.resolverWrapper
cc.mu.RUnlock()
if r == nil {
return
}
go r.resolveNow(o)
}
// ResetConnectBackoff wakes up all subchannels in transient failure and causes
// them to attempt another connection immediately. It also resets the backoff
// times used for subsequent attempts regardless of the current state.
//
// In general, this function should not be used. Typical service or network
// outages result in a reasonable client reconnection strategy by default.
// However, if a previously unavailable network becomes available, this may be
// used to trigger an immediate reconnect.
//
// This API is EXPERIMENTAL.
func (cc *ClientConn) ResetConnectBackoff() {
cc.mu.Lock()
defer cc.mu.Unlock()
for ac := range cc.conns {
ac.resetConnectBackoff()
}
}
// Close tears down the ClientConn and all underlying connections.
func (cc *ClientConn) Close() error {
defer cc.cancel()
cc.mu.Lock()
if cc.conns == nil {
cc.mu.Unlock()
return ErrClientConnClosing
}
conns := cc.conns
cc.conns = nil
cc.csMgr.updateState(connectivity.Shutdown)
rWrapper := cc.resolverWrapper
cc.resolverWrapper = nil
bWrapper := cc.balancerWrapper
cc.balancerWrapper = nil
cc.mu.Unlock()
cc.blockingpicker.close()
if rWrapper != nil {
rWrapper.close()
}
if bWrapper != nil {
bWrapper.close()
}
for ac := range conns {
ac.tearDown(ErrClientConnClosing)
}
if channelz.IsOn() {
ted := &channelz.TraceEventDesc{
Desc: "Channel Deleted",
Severity: channelz.CtINFO,
}
if cc.dopts.channelzParentID != 0 {
ted.Parent = &channelz.TraceEventDesc{
Desc: fmt.Sprintf("Nested channel(id:%d) deleted", cc.channelzID),
Severity: channelz.CtINFO,
}
}
channelz.AddTraceEvent(cc.channelzID, ted)
// TraceEvent needs to be called before RemoveEntry, as TraceEvent may add trace reference to
// the entity being deleted, and thus prevent it from being deleted right away.
channelz.RemoveEntry(cc.channelzID)
}
return nil
}
// addrConn is a network connection to a given address.
type addrConn struct {
ctx context.Context
cancel context.CancelFunc
cc *ClientConn
dopts dialOptions
acbw balancer.SubConn
scopts balancer.NewSubConnOptions
// transport is set when there's a viable transport (note: ac state may not be READY as LB channel
// health checking may require server to report healthy to set ac to READY), and is reset
// to nil when the current transport should no longer be used to create a stream (e.g. after GoAway
// is received, transport is closed, ac has been torn down).
transport transport.ClientTransport // The current transport.
mu sync.Mutex
curAddr resolver.Address // The current address.
addrs []resolver.Address // All addresses that the resolver resolved to.
// Use updateConnectivityState for updating addrConn's connectivity state.
state connectivity.State
backoffIdx int // Needs to be stateful for resetConnectBackoff.
resetBackoff chan struct{}
channelzID int64 // channelz unique identification number.
czData *channelzData
}
// Note: this requires a lock on ac.mu.
func (ac *addrConn) updateConnectivityState(s connectivity.State) {
if ac.state == s {
return
}
updateMsg := fmt.Sprintf("Subchannel Connectivity change to %v", s)
ac.state = s
if channelz.IsOn() {
channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{
Desc: updateMsg,
Severity: channelz.CtINFO,
})
}
ac.cc.handleSubConnStateChange(ac.acbw, s)
}
// adjustParams updates parameters used to create transports upon
// receiving a GoAway.
func (ac *addrConn) adjustParams(r transport.GoAwayReason) {
switch r {
case transport.GoAwayTooManyPings:
v := 2 * ac.dopts.copts.KeepaliveParams.Time
ac.cc.mu.Lock()
if v > ac.cc.mkp.Time {
ac.cc.mkp.Time = v
}
ac.cc.mu.Unlock()
}
}
func (ac *addrConn) resetTransport() {
for i := 0; ; i++ {
if i > 0 {
ac.cc.resolveNow(resolver.ResolveNowOption{})
}
ac.mu.Lock()
if ac.state == connectivity.Shutdown {
ac.mu.Unlock()
return
}
addrs := ac.addrs
backoffFor := ac.dopts.bs.Backoff(ac.backoffIdx)
// This will be the duration that dial gets to finish.
dialDuration := minConnectTimeout
if ac.dopts.minConnectTimeout != nil {
dialDuration = ac.dopts.minConnectTimeout()
}
if dialDuration < backoffFor {
// Give dial more time as we keep failing to connect.
dialDuration = backoffFor
}
// We can potentially spend all the time trying the first address, and
// if the server accepts the connection and then hangs, the following
// addresses will never be tried.
//
// The spec doesn't mention what should be done for multiple addresses.
// https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md#proposed-backoff-algorithm
connectDeadline := time.Now().Add(dialDuration)
ac.updateConnectivityState(connectivity.Connecting)
ac.transport = nil
ac.mu.Unlock()
newTr, addr, reconnect, err := ac.tryAllAddrs(addrs, connectDeadline)
if err != nil {
// After exhausting all addresses, the addrConn enters
// TRANSIENT_FAILURE.
ac.mu.Lock()
if ac.state == connectivity.Shutdown {
ac.mu.Unlock()
return
}
ac.updateConnectivityState(connectivity.TransientFailure)
// Backoff.
b := ac.resetBackoff
ac.mu.Unlock()
timer := time.NewTimer(backoffFor)
select {
case <-timer.C:
ac.mu.Lock()
ac.backoffIdx++
ac.mu.Unlock()
case <-b:
timer.Stop()
case <-ac.ctx.Done():
timer.Stop()
return
}
continue
}
ac.mu.Lock()
if ac.state == connectivity.Shutdown {
ac.mu.Unlock()
newTr.Close()
return
}
ac.curAddr = addr
ac.transport = newTr
ac.backoffIdx = 0
hctx, hcancel := context.WithCancel(ac.ctx)
ac.startHealthCheck(hctx)
ac.mu.Unlock()
// Block until the created transport is down. And when this happens,
// we restart from the top of the addr list.
<-reconnect.Done()
hcancel()
// restart connecting - the top of the loop will set state to
// CONNECTING. This is against the current connectivity semantics doc,
// however it allows for graceful behavior for RPCs not yet dispatched
// - unfortunate timing would otherwise lead to the RPC failing even
// though the TRANSIENT_FAILURE state (called for by the doc) would be
// instantaneous.
//
// Ideally we should transition to Idle here and block until there is
// RPC activity that leads to the balancer requesting a reconnect of
// the associated SubConn.
}
}
// tryAllAddrs tries to creates a connection to the addresses, and stop when at the
// first successful one. It returns the transport, the address and a Event in
// the successful case. The Event fires when the returned transport disconnects.
func (ac *addrConn) tryAllAddrs(addrs []resolver.Address, connectDeadline time.Time) (transport.ClientTransport, resolver.Address, *grpcsync.Event, error) {
for _, addr := range addrs {
ac.mu.Lock()
if ac.state == connectivity.Shutdown {
ac.mu.Unlock()
return nil, resolver.Address{}, nil, errConnClosing
}
ac.cc.mu.RLock()
ac.dopts.copts.KeepaliveParams = ac.cc.mkp
ac.cc.mu.RUnlock()
copts := ac.dopts.copts
if ac.scopts.CredsBundle != nil {
copts.CredsBundle = ac.scopts.CredsBundle
}
ac.mu.Unlock()
if channelz.IsOn() {
channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{
Desc: fmt.Sprintf("Subchannel picks a new address %q to connect", addr.Addr),
Severity: channelz.CtINFO,
})
}
newTr, reconnect, err := ac.createTransport(addr, copts, connectDeadline)
if err == nil {
return newTr, addr, reconnect, nil
}
ac.cc.blockingpicker.updateConnectionError(err)
}
// Couldn't connect to any address.
return nil, resolver.Address{}, nil, fmt.Errorf("couldn't connect to any address")
}
// createTransport creates a connection to addr. It returns the transport and a
// Event in the successful case. The Event fires when the returned transport
// disconnects.
func (ac *addrConn) createTransport(addr resolver.Address, copts transport.ConnectOptions, connectDeadline time.Time) (transport.ClientTransport, *grpcsync.Event, error) {
prefaceReceived := make(chan struct{})
onCloseCalled := make(chan struct{})
reconnect := grpcsync.NewEvent()
target := transport.TargetInfo{
Addr: addr.Addr,
Metadata: addr.Metadata,
Authority: ac.cc.authority,
}
once := sync.Once{}
onGoAway := func(r transport.GoAwayReason) {
ac.mu.Lock()
ac.adjustParams(r)
once.Do(func() {
if ac.state == connectivity.Ready {
// Prevent this SubConn from being used for new RPCs by setting its
// state to Connecting.
//
// TODO: this should be Idle when grpc-go properly supports it.
ac.updateConnectivityState(connectivity.Connecting)
}
})
ac.mu.Unlock()
reconnect.Fire()
}
onClose := func() {
ac.mu.Lock()
once.Do(func() {
if ac.state == connectivity.Ready {
// Prevent this SubConn from being used for new RPCs by setting its
// state to Connecting.
//
// TODO: this should be Idle when grpc-go properly supports it.
ac.updateConnectivityState(connectivity.Connecting)
}
})
ac.mu.Unlock()
close(onCloseCalled)
reconnect.Fire()
}
onPrefaceReceipt := func() {
close(prefaceReceived)
}
connectCtx, cancel := context.WithDeadline(ac.ctx, connectDeadline)
defer cancel()
if channelz.IsOn() {
copts.ChannelzParentID = ac.channelzID
}
newTr, err := transport.NewClientTransport(connectCtx, ac.cc.ctx, target, copts, onPrefaceReceipt, onGoAway, onClose)
if err != nil {
// newTr is either nil, or closed.
grpclog.Warningf("grpc: addrConn.createTransport failed to connect to %v. Err :%v. Reconnecting...", addr, err)
return nil, nil, err
}
select {
case <-time.After(connectDeadline.Sub(time.Now())):
// We didn't get the preface in time.
newTr.Close()
grpclog.Warningf("grpc: addrConn.createTransport failed to connect to %v: didn't receive server preface in time. Reconnecting...", addr)
return nil, nil, errors.New("timed out waiting for server handshake")
case <-prefaceReceived:
// We got the preface - huzzah! things are good.
case <-onCloseCalled:
// The transport has already closed - noop.
return nil, nil, errors.New("connection closed")
// TODO(deklerk) this should bail on ac.ctx.Done(). Add a test and fix.
}
return newTr, reconnect, nil
}
// startHealthCheck starts the health checking stream (RPC) to watch the health
// stats of this connection if health checking is requested and configured.
//
// LB channel health checking is enabled when all requirements below are met:
// 1. it is not disabled by the user with the WithDisableHealthCheck DialOption
// 2. internal.HealthCheckFunc is set by importing the grpc/healthcheck package
// 3. a service config with non-empty healthCheckConfig field is provided
// 4. the load balancer requests it
//
// It sets addrConn to READY if the health checking stream is not started.
//
// Caller must hold ac.mu.
func (ac *addrConn) startHealthCheck(ctx context.Context) {
var healthcheckManagingState bool
defer func() {
if !healthcheckManagingState {
ac.updateConnectivityState(connectivity.Ready)
}
}()
if ac.cc.dopts.disableHealthCheck {
return
}
healthCheckConfig := ac.cc.healthCheckConfig()
if healthCheckConfig == nil {
return
}
if !ac.scopts.HealthCheckEnabled {
return
}
healthCheckFunc := ac.cc.dopts.healthCheckFunc
if healthCheckFunc == nil {
// The health package is not imported to set health check function.
//
// TODO: add a link to the health check doc in the error message.
grpclog.Error("Health check is requested but health check function is not set.")
return
}
healthcheckManagingState = true
// Set up the health check helper functions.
currentTr := ac.transport
newStream := func(method string) (interface{}, error) {
ac.mu.Lock()
if ac.transport != currentTr {
ac.mu.Unlock()
return nil, status.Error(codes.Canceled, "the provided transport is no longer valid to use")
}
ac.mu.Unlock()
return newNonRetryClientStream(ctx, &StreamDesc{ServerStreams: true}, method, currentTr, ac)
}
setConnectivityState := func(s connectivity.State) {
ac.mu.Lock()
defer ac.mu.Unlock()
if ac.transport != currentTr {
return
}
ac.updateConnectivityState(s)
}
// Start the health checking stream.
go func() {
err := ac.cc.dopts.healthCheckFunc(ctx, newStream, setConnectivityState, healthCheckConfig.ServiceName)
if err != nil {
if status.Code(err) == codes.Unimplemented {
if channelz.IsOn() {
channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{
Desc: "Subchannel health check is unimplemented at server side, thus health check is disabled",
Severity: channelz.CtError,
})
}
grpclog.Error("Subchannel health check is unimplemented at server side, thus health check is disabled")
} else {
grpclog.Errorf("HealthCheckFunc exits with unexpected error %v", err)
}
}
}()
}
func (ac *addrConn) resetConnectBackoff() {
ac.mu.Lock()
close(ac.resetBackoff)
ac.backoffIdx = 0
ac.resetBackoff = make(chan struct{})
ac.mu.Unlock()
}
// getReadyTransport returns the transport if ac's state is READY.
// Otherwise it returns nil, false.
// If ac's state is IDLE, it will trigger ac to connect.
func (ac *addrConn) getReadyTransport() (transport.ClientTransport, bool) {
ac.mu.Lock()
if ac.state == connectivity.Ready && ac.transport != nil {
t := ac.transport
ac.mu.Unlock()
return t, true
}
var idle bool
if ac.state == connectivity.Idle {
idle = true
}
ac.mu.Unlock()
// Trigger idle ac to connect.
if idle {
ac.connect()
}
return nil, false
}
// tearDown starts to tear down the addrConn.
// TODO(zhaoq): Make this synchronous to avoid unbounded memory consumption in
// some edge cases (e.g., the caller opens and closes many addrConn's in a
// tight loop.
// tearDown doesn't remove ac from ac.cc.conns.
func (ac *addrConn) tearDown(err error) {
ac.mu.Lock()
if ac.state == connectivity.Shutdown {
ac.mu.Unlock()
return
}
curTr := ac.transport
ac.transport = nil
// We have to set the state to Shutdown before anything else to prevent races
// between setting the state and logic that waits on context cancelation / etc.
ac.updateConnectivityState(connectivity.Shutdown)
ac.cancel()
ac.curAddr = resolver.Address{}
if err == errConnDrain && curTr != nil {
// GracefulClose(...) may be executed multiple times when
// i) receiving multiple GoAway frames from the server; or
// ii) there are concurrent name resolver/Balancer triggered
// address removal and GoAway.
// We have to unlock and re-lock here because GracefulClose => Close => onClose, which requires locking ac.mu.
ac.mu.Unlock()
curTr.GracefulClose()
ac.mu.Lock()
}
if channelz.IsOn() {
channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{
Desc: "Subchannel Deleted",
Severity: channelz.CtINFO,
Parent: &channelz.TraceEventDesc{
Desc: fmt.Sprintf("Subchanel(id:%d) deleted", ac.channelzID),
Severity: channelz.CtINFO,
},
})
// TraceEvent needs to be called before RemoveEntry, as TraceEvent may add trace reference to
// the entity beng deleted, and thus prevent it from being deleted right away.
channelz.RemoveEntry(ac.channelzID)
}
ac.mu.Unlock()
}
func (ac *addrConn) getState() connectivity.State {
ac.mu.Lock()
defer ac.mu.Unlock()
return ac.state
}
func (ac *addrConn) ChannelzMetric() *channelz.ChannelInternalMetric {
ac.mu.Lock()
addr := ac.curAddr.Addr
ac.mu.Unlock()
return &channelz.ChannelInternalMetric{
State: ac.getState(),
Target: addr,
CallsStarted: atomic.LoadInt64(&ac.czData.callsStarted),
CallsSucceeded: atomic.LoadInt64(&ac.czData.callsSucceeded),
CallsFailed: atomic.LoadInt64(&ac.czData.callsFailed),
LastCallStartedTimestamp: time.Unix(0, atomic.LoadInt64(&ac.czData.lastCallStartedTime)),
}
}
func (ac *addrConn) incrCallsStarted() {
atomic.AddInt64(&ac.czData.callsStarted, 1)
atomic.StoreInt64(&ac.czData.lastCallStartedTime, time.Now().UnixNano())
}
func (ac *addrConn) incrCallsSucceeded() {
atomic.AddInt64(&ac.czData.callsSucceeded, 1)
}
func (ac *addrConn) incrCallsFailed() {
atomic.AddInt64(&ac.czData.callsFailed, 1)
}
type retryThrottler struct {
max float64
thresh float64
ratio float64
mu sync.Mutex
tokens float64 // TODO(dfawley): replace with atomic and remove lock.
}
// throttle subtracts a retry token from the pool and returns whether a retry
// should be throttled (disallowed) based upon the retry throttling policy in
// the service config.
func (rt *retryThrottler) throttle() bool {
if rt == nil {
return false
}
rt.mu.Lock()
defer rt.mu.Unlock()
rt.tokens--
if rt.tokens < 0 {
rt.tokens = 0
}
return rt.tokens <= rt.thresh
}
func (rt *retryThrottler) successfulRPC() {
if rt == nil {
return
}
rt.mu.Lock()
defer rt.mu.Unlock()
rt.tokens += rt.ratio
if rt.tokens > rt.max {
rt.tokens = rt.max
}
}
type channelzChannel struct {
cc *ClientConn
}
func (c *channelzChannel) ChannelzMetric() *channelz.ChannelInternalMetric {
return c.cc.channelzMetric()
}
// ErrClientConnTimeout indicates that the ClientConn cannot establish the
// underlying connections within the specified timeout.
//
// Deprecated: This error is never returned by grpc and should not be
// referenced by users.
var ErrClientConnTimeout = errors.New("grpc: timed out when dialing")
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