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clientconn.go
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clientconn.go
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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/url"
"reflect"
"strings"
"sync"
"sync/atomic"
"time"
"google.golang.org/grpc/balancer"
"google.golang.org/grpc/balancer/base"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/connectivity"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/internal/backoff"
"google.golang.org/grpc/internal/channelz"
"google.golang.org/grpc/internal/grpcsync"
iresolver "google.golang.org/grpc/internal/resolver"
"google.golang.org/grpc/internal/transport"
"google.golang.org/grpc/keepalive"
"google.golang.org/grpc/resolver"
"google.golang.org/grpc/serviceconfig"
"google.golang.org/grpc/status"
_ "google.golang.org/grpc/balancer/roundrobin" // To register roundrobin.
_ "google.golang.org/grpc/internal/resolver/dns" // To register dns resolver.
_ "google.golang.org/grpc/internal/resolver/passthrough" // To register passthrough resolver.
_ "google.golang.org/grpc/internal/resolver/unix" // To register unix resolver.
)
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")
// 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.WithTransportCredentials(insecure.NewCredentials()) 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")
// errNoTransportCredsInBundle indicated that the configured creds bundle
// returned a transport credentials which was nil.
errNoTransportCredsInBundle = errors.New("grpc: credentials.Bundle must return non-nil transport credentials")
// 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)")
)
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...)
}
type defaultConfigSelector struct {
sc *ServiceConfig
}
func (dcs *defaultConfigSelector) SelectConfig(rpcInfo iresolver.RPCInfo) (*iresolver.RPCConfig, error) {
return &iresolver.RPCConfig{
Context: rpcInfo.Context,
MethodConfig: getMethodConfig(dcs.sc, rpcInfo.Method),
}, nil
}
// 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.safeConfigSelector.UpdateConfigSelector(&defaultConfigSelector{nil})
cc.ctx, cc.cancel = context.WithCancel(context.Background())
for _, opt := range extraDialOptions {
opt.apply(&cc.dopts)
}
for _, opt := range opts {
opt.apply(&cc.dopts)
}
chainUnaryClientInterceptors(cc)
chainStreamClientInterceptors(cc)
defer func() {
if err != nil {
cc.Close()
}
}()
pid := cc.dopts.channelzParentID
cc.channelzID = channelz.RegisterChannel(&channelzChannel{cc}, pid, target)
ted := &channelz.TraceEventDesc{
Desc: "Channel created",
Severity: channelz.CtInfo,
}
if cc.dopts.channelzParentID != nil {
ted.Parent = &channelz.TraceEventDesc{
Desc: fmt.Sprintf("Nested Channel(id:%d) created", cc.channelzID.Int()),
Severity: channelz.CtInfo,
}
}
channelz.AddTraceEvent(logger, cc.channelzID, 1, ted)
cc.csMgr.channelzID = cc.channelzID
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
}
if cc.dopts.copts.CredsBundle != nil && cc.dopts.copts.CredsBundle.TransportCredentials() == nil {
return nil, errNoTransportCredsInBundle
}
transportCreds := cc.dopts.copts.TransportCredentials
if transportCreds == nil {
transportCreds = cc.dopts.copts.CredsBundle.TransportCredentials()
}
if transportCreds.Info().SecurityProtocol == "insecure" {
for _, cd := range cc.dopts.copts.PerRPCCredentials {
if cd.RequireTransportSecurity() {
return nil, errTransportCredentialsMissing
}
}
}
if cc.dopts.defaultServiceConfigRawJSON != nil {
scpr := parseServiceConfig(*cc.dopts.defaultServiceConfigRawJSON)
if scpr.Err != nil {
return nil, fmt.Errorf("%s: %v", invalidDefaultServiceConfigErrPrefix, scpr.Err)
}
cc.dopts.defaultServiceConfig, _ = scpr.Config.(*ServiceConfig)
}
cc.mkp = cc.dopts.copts.KeepaliveParams
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():
switch {
case ctx.Err() == err:
conn = nil
case err == nil || !cc.dopts.returnLastError:
conn, err = nil, ctx.Err()
default:
conn, err = nil, fmt.Errorf("%v: %v", ctx.Err(), 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
cc.safeConfigSelector.UpdateConfigSelector(&defaultConfigSelector{&sc})
scSet = true
}
default:
}
}
if cc.dopts.bs == nil {
cc.dopts.bs = backoff.DefaultExponential
}
// Determine the resolver to use.
resolverBuilder, err := cc.parseTargetAndFindResolver()
if err != nil {
return nil, err
}
cc.authority, err = determineAuthority(cc.parsedTarget.Endpoint, cc.target, cc.dopts)
if err != nil {
return nil, err
}
channelz.Infof(logger, cc.channelzID, "Channel authority set to %q", cc.authority)
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
cc.safeConfigSelector.UpdateConfigSelector(&defaultConfigSelector{&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.balancerWrapper = newCCBalancerWrapper(cc, balancer.BuildOptions{
DialCreds: credsClone,
CredsBundle: cc.dopts.copts.CredsBundle,
Dialer: cc.dopts.copts.Dialer,
Authority: cc.authority,
CustomUserAgent: cc.dopts.copts.UserAgent,
ChannelzParentID: cc.channelzID,
Target: cc.parsedTarget,
})
// Build the resolver.
rWrapper, err := newCCResolverWrapper(cc, resolverBuilder)
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 {
cc.Connect()
s := cc.GetState()
if s == connectivity.Ready {
break
} else if cc.dopts.copts.FailOnNonTempDialError && s == connectivity.TransientFailure {
if err = cc.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.
if err = cc.connectionError(); err != nil && cc.dopts.returnLastError {
return nil, err
}
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 *channelz.Identifier
}
// 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
channelz.Infof(logger, csm.channelzID, "Channel Connectivity change to %v", state)
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
}
// ClientConnInterface defines the functions clients need to perform unary and
// streaming RPCs. It is implemented by *ClientConn, and is only intended to
// be referenced by generated code.
type ClientConnInterface interface {
// Invoke performs a unary RPC and returns after the response is received
// into reply.
Invoke(ctx context.Context, method string, args interface{}, reply interface{}, opts ...CallOption) error
// NewStream begins a streaming RPC.
NewStream(ctx context.Context, desc *StreamDesc, method string, opts ...CallOption) (ClientStream, error)
}
// Assert *ClientConn implements ClientConnInterface.
var _ ClientConnInterface = (*ClientConn)(nil)
// ClientConn represents a virtual connection to a conceptual endpoint, to
// perform RPCs.
//
// A ClientConn is free to have zero or more actual connections to the endpoint
// based on configuration, load, etc. It is also free to determine which actual
// endpoints to use and may change it every RPC, permitting client-side load
// balancing.
//
// A ClientConn encapsulates a range of functionality including name
// resolution, TCP connection establishment (with retries and backoff) and TLS
// handshakes. It also handles errors on established connections by
// re-resolving the name and reconnecting.
type ClientConn struct {
ctx context.Context // Initialized using the background context at dial time.
cancel context.CancelFunc // Cancelled on close.
// The following are initialized at dial time, and are read-only after that.
target string // User's dial target.
parsedTarget resolver.Target // See parseTargetAndFindResolver().
authority string // See determineAuthority().
dopts dialOptions // Default and user specified dial options.
channelzID *channelz.Identifier // Channelz identifier for the channel.
balancerWrapper *ccBalancerWrapper // Uses gracefulswitch.balancer underneath.
// The following provide their own synchronization, and therefore don't
// require cc.mu to be held to access them.
csMgr *connectivityStateManager
blockingpicker *pickerWrapper
safeConfigSelector iresolver.SafeConfigSelector
czData *channelzData
retryThrottler atomic.Value // Updated from service config.
// firstResolveEvent is used to track whether the name resolver sent us at
// least one update. RPCs block on this event.
firstResolveEvent *grpcsync.Event
// mu protects the following fields.
// TODO: split mu so the same mutex isn't used for everything.
mu sync.RWMutex
resolverWrapper *ccResolverWrapper // Initialized in Dial; cleared in Close.
sc *ServiceConfig // Latest service config received from the resolver.
conns map[*addrConn]struct{} // Set to nil on close.
mkp keepalive.ClientParameters // May be updated upon receipt of a GoAway.
lceMu sync.Mutex // protects lastConnectionError
lastConnectionError error
}
// 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.
//
// Experimental
//
// Notice: This API is EXPERIMENTAL and may be changed or removed in a
// later release.
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.
//
// Experimental
//
// Notice: This API is EXPERIMENTAL and may be changed or removed in a later
// release.
func (cc *ClientConn) GetState() connectivity.State {
return cc.csMgr.getState()
}
// Connect causes all subchannels in the ClientConn to attempt to connect if
// the channel is idle. Does not wait for the connection attempts to begin
// before returning.
//
// Experimental
//
// Notice: This API is EXPERIMENTAL and may be changed or removed in a later
// release.
func (cc *ClientConn) Connect() {
cc.balancerWrapper.exitIdle()
}
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.safeConfigSelector.UpdateConfigSelector(&defaultConfigSelector{&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
}
}
var emptyServiceConfig *ServiceConfig
func init() {
cfg := parseServiceConfig("{}")
if cfg.Err != nil {
panic(fmt.Sprintf("impossible error parsing empty service config: %v", cfg.Err))
}
emptyServiceConfig = cfg.Config.(*ServiceConfig)
}
func (cc *ClientConn) maybeApplyDefaultServiceConfig(addrs []resolver.Address) {
if cc.sc != nil {
cc.applyServiceConfigAndBalancer(cc.sc, nil, addrs)
return
}
if cc.dopts.defaultServiceConfig != nil {
cc.applyServiceConfigAndBalancer(cc.dopts.defaultServiceConfig, &defaultConfigSelector{cc.dopts.defaultServiceConfig}, addrs)
} else {
cc.applyServiceConfigAndBalancer(emptyServiceConfig, &defaultConfigSelector{emptyServiceConfig}, addrs)
}
}
func (cc *ClientConn) updateResolverState(s resolver.State, err error) error {
defer cc.firstResolveEvent.Fire()
cc.mu.Lock()
// 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 {
cc.mu.Unlock()
return nil
}
if err != nil {
// May need to apply the initial service config in case the resolver
// doesn't support service configs, or doesn't provide a service config
// with the new addresses.
cc.maybeApplyDefaultServiceConfig(nil)
cc.balancerWrapper.resolverError(err)
// No addresses are valid with err set; return early.
cc.mu.Unlock()
return balancer.ErrBadResolverState
}
var ret error
if cc.dopts.disableServiceConfig {
channelz.Infof(logger, cc.channelzID, "ignoring service config from resolver (%v) and applying the default because service config is disabled", s.ServiceConfig)
cc.maybeApplyDefaultServiceConfig(s.Addresses)
} else if s.ServiceConfig == nil {
cc.maybeApplyDefaultServiceConfig(s.Addresses)
// TODO: do we need to apply a failing LB policy if there is no
// default, per the error handling design?
} else {
if sc, ok := s.ServiceConfig.Config.(*ServiceConfig); s.ServiceConfig.Err == nil && ok {
configSelector := iresolver.GetConfigSelector(s)
if configSelector != nil {
if len(s.ServiceConfig.Config.(*ServiceConfig).Methods) != 0 {
channelz.Infof(logger, cc.channelzID, "method configs in service config will be ignored due to presence of config selector")
}
} else {
configSelector = &defaultConfigSelector{sc}
}
cc.applyServiceConfigAndBalancer(sc, configSelector, s.Addresses)
} else {
ret = balancer.ErrBadResolverState
if cc.sc == nil {
// Apply the failing LB only if we haven't received valid service config
// from the name resolver in the past.
cc.applyFailingLB(s.ServiceConfig)
cc.mu.Unlock()
return ret
}
}
}
var balCfg serviceconfig.LoadBalancingConfig
if cc.sc != nil && cc.sc.lbConfig != nil {
balCfg = cc.sc.lbConfig.cfg
}
bw := cc.balancerWrapper
cc.mu.Unlock()
uccsErr := bw.updateClientConnState(&balancer.ClientConnState{ResolverState: s, BalancerConfig: balCfg})
if ret == nil {
ret = uccsErr // prefer ErrBadResolver state since any other error is
// currently meaningless to the caller.
}
return ret
}
// applyFailingLB is akin to configuring an LB policy on the channel which
// always fails RPCs. Here, an actual LB policy is not configured, but an always
// erroring picker is configured, which returns errors with information about
// what was invalid in the received service config. A config selector with no
// service config is configured, and the connectivity state of the channel is
// set to TransientFailure.
//
// Caller must hold cc.mu.
func (cc *ClientConn) applyFailingLB(sc *serviceconfig.ParseResult) {
var err error
if sc.Err != nil {
err = status.Errorf(codes.Unavailable, "error parsing service config: %v", sc.Err)
} else {
err = status.Errorf(codes.Unavailable, "illegal service config type: %T", sc.Config)
}
cc.safeConfigSelector.UpdateConfigSelector(&defaultConfigSelector{nil})
cc.blockingpicker.updatePicker(base.NewErrPicker(err))
cc.csMgr.updateState(connectivity.TransientFailure)
}
func (cc *ClientConn) handleSubConnStateChange(sc balancer.SubConn, s connectivity.State, err error) {
cc.balancerWrapper.updateSubConnState(sc, s, err)
}
// 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{
state: connectivity.Idle,
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
}
var err error
ac.channelzID, err = channelz.RegisterSubChannel(ac, cc.channelzID, "")
if err != nil {
return nil, err
}
channelz.AddTraceEvent(logger, ac.channelzID, 0, &channelz.TraceEventDesc{
Desc: "Subchannel created",
Severity: channelz.CtInfo,
Parent: &channelz.TraceEventDesc{
Desc: fmt.Sprintf("Subchannel(id:%d) created", ac.channelzID.Int()),
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.
//
// Experimental
//
// Notice: This API is EXPERIMENTAL and may be changed or removed in a
// later release.
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, nil)
ac.mu.Unlock()
ac.resetTransport()
return nil
}
func equalAddresses(a, b []resolver.Address) bool {
if len(a) != len(b) {
return false
}
for i, v := range a {
if !v.Equal(b[i]) {
return false
}
}
return true
}
// tryUpdateAddrs tries to update ac.addrs with the new addresses list.
//
// 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 the addresses is the same as the old list, it does nothing and returns
// true.
//
// 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 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()
channelz.Infof(logger, ac.channelzID, "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 equalAddresses(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 {
a.ServerName = ac.cc.getServerName(a)
if reflect.DeepEqual(ac.curAddr, a) {
curAddrFound = true
break
}
}
channelz.Infof(logger, ac.channelzID, "addrConn: tryUpdateAddrs curAddrFound: %v", curAddrFound)
if curAddrFound {
ac.addrs = addrs
}
return curAddrFound
}
// getServerName determines the serverName to be used in the connection
// handshake. The default value for the serverName is the authority on the
// ClientConn, which either comes from the user's dial target or through an
// authority override specified using the WithAuthority dial option. Name
// resolvers can specify a per-address override for the serverName through the
// resolver.Address.ServerName field which is used only if the WithAuthority
// dial option was not used. The rationale is that per-address authority
// overrides specified by the name resolver can represent a security risk, while
// an override specified by the user is more dependable since they probably know
// what they are doing.
func (cc *ClientConn) getServerName(addr resolver.Address) string {
if cc.dopts.authority != "" {
return cc.dopts.authority
}
if addr.ServerName != "" {
return addr.ServerName
}
return cc.authority
}
func getMethodConfig(sc *ServiceConfig, method string) MethodConfig {
if sc == nil {
return MethodConfig{}
}
if m, ok := sc.Methods[method]; ok {
return m
}
i := strings.LastIndex(method, "/")
if m, ok := sc.Methods[method[:i+1]]; ok {
return m
}
return sc.Methods[""]
}
// 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 service's default
// config under the service (i.e /service/) and then for the default for all services (empty string).
//
// 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()
return getMethodConfig(cc.sc, method)
}
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) {
return cc.blockingpicker.pick(ctx, failfast, balancer.PickInfo{
Ctx: ctx,
FullMethodName: method,
})
}
func (cc *ClientConn) applyServiceConfigAndBalancer(sc *ServiceConfig, configSelector iresolver.ConfigSelector, addrs []resolver.Address) {
if sc == nil {
// should never reach here.
return
}
cc.sc = sc
if configSelector != nil {
cc.safeConfigSelector.UpdateConfigSelector(configSelector)
}
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))
}
var newBalancerName string
if cc.sc != nil && cc.sc.lbConfig != nil {
newBalancerName = cc.sc.lbConfig.name
} else {
var isGRPCLB bool
for _, a := range addrs {
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.balancerWrapper.switchTo(newBalancerName)
}
func (cc *ClientConn) resolveNow(o resolver.ResolveNowOptions) {
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.