Elia Battiston | be9edc1 | 2022-03-09 11:35:58 +0100 | [diff] [blame^] | 1 | /* |
| 2 | * |
| 3 | * Copyright 2014 gRPC authors. |
| 4 | * |
| 5 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | * you may not use this file except in compliance with the License. |
| 7 | * You may obtain a copy of the License at |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | * See the License for the specific language governing permissions and |
| 15 | * limitations under the License. |
| 16 | * |
| 17 | */ |
| 18 | |
| 19 | package grpc |
| 20 | |
| 21 | import ( |
| 22 | "context" |
| 23 | "errors" |
| 24 | "fmt" |
| 25 | "math" |
| 26 | "net" |
| 27 | "reflect" |
| 28 | "strings" |
| 29 | "sync" |
| 30 | "sync/atomic" |
| 31 | "time" |
| 32 | |
| 33 | "google.golang.org/grpc/balancer" |
| 34 | "google.golang.org/grpc/balancer/base" |
| 35 | "google.golang.org/grpc/codes" |
| 36 | "google.golang.org/grpc/connectivity" |
| 37 | "google.golang.org/grpc/credentials" |
| 38 | "google.golang.org/grpc/grpclog" |
| 39 | "google.golang.org/grpc/internal/backoff" |
| 40 | "google.golang.org/grpc/internal/channelz" |
| 41 | "google.golang.org/grpc/internal/grpcsync" |
| 42 | "google.golang.org/grpc/internal/transport" |
| 43 | "google.golang.org/grpc/keepalive" |
| 44 | "google.golang.org/grpc/resolver" |
| 45 | "google.golang.org/grpc/serviceconfig" |
| 46 | "google.golang.org/grpc/status" |
| 47 | |
| 48 | _ "google.golang.org/grpc/balancer/roundrobin" // To register roundrobin. |
| 49 | _ "google.golang.org/grpc/internal/resolver/dns" // To register dns resolver. |
| 50 | _ "google.golang.org/grpc/internal/resolver/passthrough" // To register passthrough resolver. |
| 51 | ) |
| 52 | |
| 53 | const ( |
| 54 | // minimum time to give a connection to complete |
| 55 | minConnectTimeout = 20 * time.Second |
| 56 | // must match grpclbName in grpclb/grpclb.go |
| 57 | grpclbName = "grpclb" |
| 58 | ) |
| 59 | |
| 60 | var ( |
| 61 | // ErrClientConnClosing indicates that the operation is illegal because |
| 62 | // the ClientConn is closing. |
| 63 | // |
| 64 | // Deprecated: this error should not be relied upon by users; use the status |
| 65 | // code of Canceled instead. |
| 66 | ErrClientConnClosing = status.Error(codes.Canceled, "grpc: the client connection is closing") |
| 67 | // errConnDrain indicates that the connection starts to be drained and does not accept any new RPCs. |
| 68 | errConnDrain = errors.New("grpc: the connection is drained") |
| 69 | // errConnClosing indicates that the connection is closing. |
| 70 | errConnClosing = errors.New("grpc: the connection is closing") |
| 71 | // errBalancerClosed indicates that the balancer is closed. |
| 72 | errBalancerClosed = errors.New("grpc: balancer is closed") |
| 73 | // invalidDefaultServiceConfigErrPrefix is used to prefix the json parsing error for the default |
| 74 | // service config. |
| 75 | invalidDefaultServiceConfigErrPrefix = "grpc: the provided default service config is invalid" |
| 76 | ) |
| 77 | |
| 78 | // The following errors are returned from Dial and DialContext |
| 79 | var ( |
| 80 | // errNoTransportSecurity indicates that there is no transport security |
| 81 | // being set for ClientConn. Users should either set one or explicitly |
| 82 | // call WithInsecure DialOption to disable security. |
| 83 | errNoTransportSecurity = errors.New("grpc: no transport security set (use grpc.WithInsecure() explicitly or set credentials)") |
| 84 | // errTransportCredsAndBundle indicates that creds bundle is used together |
| 85 | // with other individual Transport Credentials. |
| 86 | errTransportCredsAndBundle = errors.New("grpc: credentials.Bundle may not be used with individual TransportCredentials") |
| 87 | // errTransportCredentialsMissing indicates that users want to transmit security |
| 88 | // information (e.g., OAuth2 token) which requires secure connection on an insecure |
| 89 | // connection. |
| 90 | errTransportCredentialsMissing = errors.New("grpc: the credentials require transport level security (use grpc.WithTransportCredentials() to set)") |
| 91 | // errCredentialsConflict indicates that grpc.WithTransportCredentials() |
| 92 | // and grpc.WithInsecure() are both called for a connection. |
| 93 | errCredentialsConflict = errors.New("grpc: transport credentials are set for an insecure connection (grpc.WithTransportCredentials() and grpc.WithInsecure() are both called)") |
| 94 | ) |
| 95 | |
| 96 | const ( |
| 97 | defaultClientMaxReceiveMessageSize = 1024 * 1024 * 4 |
| 98 | defaultClientMaxSendMessageSize = math.MaxInt32 |
| 99 | // http2IOBufSize specifies the buffer size for sending frames. |
| 100 | defaultWriteBufSize = 32 * 1024 |
| 101 | defaultReadBufSize = 32 * 1024 |
| 102 | ) |
| 103 | |
| 104 | // Dial creates a client connection to the given target. |
| 105 | func Dial(target string, opts ...DialOption) (*ClientConn, error) { |
| 106 | return DialContext(context.Background(), target, opts...) |
| 107 | } |
| 108 | |
| 109 | // DialContext creates a client connection to the given target. By default, it's |
| 110 | // a non-blocking dial (the function won't wait for connections to be |
| 111 | // established, and connecting happens in the background). To make it a blocking |
| 112 | // dial, use WithBlock() dial option. |
| 113 | // |
| 114 | // In the non-blocking case, the ctx does not act against the connection. It |
| 115 | // only controls the setup steps. |
| 116 | // |
| 117 | // In the blocking case, ctx can be used to cancel or expire the pending |
| 118 | // connection. Once this function returns, the cancellation and expiration of |
| 119 | // ctx will be noop. Users should call ClientConn.Close to terminate all the |
| 120 | // pending operations after this function returns. |
| 121 | // |
| 122 | // The target name syntax is defined in |
| 123 | // https://github.com/grpc/grpc/blob/master/doc/naming.md. |
| 124 | // e.g. to use dns resolver, a "dns:///" prefix should be applied to the target. |
| 125 | func DialContext(ctx context.Context, target string, opts ...DialOption) (conn *ClientConn, err error) { |
| 126 | cc := &ClientConn{ |
| 127 | target: target, |
| 128 | csMgr: &connectivityStateManager{}, |
| 129 | conns: make(map[*addrConn]struct{}), |
| 130 | dopts: defaultDialOptions(), |
| 131 | blockingpicker: newPickerWrapper(), |
| 132 | czData: new(channelzData), |
| 133 | firstResolveEvent: grpcsync.NewEvent(), |
| 134 | } |
| 135 | cc.retryThrottler.Store((*retryThrottler)(nil)) |
| 136 | cc.ctx, cc.cancel = context.WithCancel(context.Background()) |
| 137 | |
| 138 | for _, opt := range opts { |
| 139 | opt.apply(&cc.dopts) |
| 140 | } |
| 141 | |
| 142 | chainUnaryClientInterceptors(cc) |
| 143 | chainStreamClientInterceptors(cc) |
| 144 | |
| 145 | defer func() { |
| 146 | if err != nil { |
| 147 | cc.Close() |
| 148 | } |
| 149 | }() |
| 150 | |
| 151 | if channelz.IsOn() { |
| 152 | if cc.dopts.channelzParentID != 0 { |
| 153 | cc.channelzID = channelz.RegisterChannel(&channelzChannel{cc}, cc.dopts.channelzParentID, target) |
| 154 | channelz.AddTraceEvent(cc.channelzID, &channelz.TraceEventDesc{ |
| 155 | Desc: "Channel Created", |
| 156 | Severity: channelz.CtINFO, |
| 157 | Parent: &channelz.TraceEventDesc{ |
| 158 | Desc: fmt.Sprintf("Nested Channel(id:%d) created", cc.channelzID), |
| 159 | Severity: channelz.CtINFO, |
| 160 | }, |
| 161 | }) |
| 162 | } else { |
| 163 | cc.channelzID = channelz.RegisterChannel(&channelzChannel{cc}, 0, target) |
| 164 | channelz.AddTraceEvent(cc.channelzID, &channelz.TraceEventDesc{ |
| 165 | Desc: "Channel Created", |
| 166 | Severity: channelz.CtINFO, |
| 167 | }) |
| 168 | } |
| 169 | cc.csMgr.channelzID = cc.channelzID |
| 170 | } |
| 171 | |
| 172 | if !cc.dopts.insecure { |
| 173 | if cc.dopts.copts.TransportCredentials == nil && cc.dopts.copts.CredsBundle == nil { |
| 174 | return nil, errNoTransportSecurity |
| 175 | } |
| 176 | if cc.dopts.copts.TransportCredentials != nil && cc.dopts.copts.CredsBundle != nil { |
| 177 | return nil, errTransportCredsAndBundle |
| 178 | } |
| 179 | } else { |
| 180 | if cc.dopts.copts.TransportCredentials != nil || cc.dopts.copts.CredsBundle != nil { |
| 181 | return nil, errCredentialsConflict |
| 182 | } |
| 183 | for _, cd := range cc.dopts.copts.PerRPCCredentials { |
| 184 | if cd.RequireTransportSecurity() { |
| 185 | return nil, errTransportCredentialsMissing |
| 186 | } |
| 187 | } |
| 188 | } |
| 189 | |
| 190 | if cc.dopts.defaultServiceConfigRawJSON != nil { |
| 191 | scpr := parseServiceConfig(*cc.dopts.defaultServiceConfigRawJSON) |
| 192 | if scpr.Err != nil { |
| 193 | return nil, fmt.Errorf("%s: %v", invalidDefaultServiceConfigErrPrefix, scpr.Err) |
| 194 | } |
| 195 | cc.dopts.defaultServiceConfig, _ = scpr.Config.(*ServiceConfig) |
| 196 | } |
| 197 | cc.mkp = cc.dopts.copts.KeepaliveParams |
| 198 | |
| 199 | if cc.dopts.copts.Dialer == nil { |
| 200 | cc.dopts.copts.Dialer = newProxyDialer( |
| 201 | func(ctx context.Context, addr string) (net.Conn, error) { |
| 202 | network, addr := parseDialTarget(addr) |
| 203 | return (&net.Dialer{}).DialContext(ctx, network, addr) |
| 204 | }, |
| 205 | ) |
| 206 | } |
| 207 | |
| 208 | if cc.dopts.copts.UserAgent != "" { |
| 209 | cc.dopts.copts.UserAgent += " " + grpcUA |
| 210 | } else { |
| 211 | cc.dopts.copts.UserAgent = grpcUA |
| 212 | } |
| 213 | |
| 214 | if cc.dopts.timeout > 0 { |
| 215 | var cancel context.CancelFunc |
| 216 | ctx, cancel = context.WithTimeout(ctx, cc.dopts.timeout) |
| 217 | defer cancel() |
| 218 | } |
| 219 | defer func() { |
| 220 | select { |
| 221 | case <-ctx.Done(): |
| 222 | conn, err = nil, ctx.Err() |
| 223 | default: |
| 224 | } |
| 225 | }() |
| 226 | |
| 227 | scSet := false |
| 228 | if cc.dopts.scChan != nil { |
| 229 | // Try to get an initial service config. |
| 230 | select { |
| 231 | case sc, ok := <-cc.dopts.scChan: |
| 232 | if ok { |
| 233 | cc.sc = &sc |
| 234 | scSet = true |
| 235 | } |
| 236 | default: |
| 237 | } |
| 238 | } |
| 239 | if cc.dopts.bs == nil { |
| 240 | cc.dopts.bs = backoff.DefaultExponential |
| 241 | } |
| 242 | if cc.dopts.resolverBuilder == nil { |
| 243 | // Only try to parse target when resolver builder is not already set. |
| 244 | cc.parsedTarget = parseTarget(cc.target) |
| 245 | grpclog.Infof("parsed scheme: %q", cc.parsedTarget.Scheme) |
| 246 | cc.dopts.resolverBuilder = resolver.Get(cc.parsedTarget.Scheme) |
| 247 | if cc.dopts.resolverBuilder == nil { |
| 248 | // If resolver builder is still nil, the parsed target's scheme is |
| 249 | // not registered. Fallback to default resolver and set Endpoint to |
| 250 | // the original target. |
| 251 | grpclog.Infof("scheme %q not registered, fallback to default scheme", cc.parsedTarget.Scheme) |
| 252 | cc.parsedTarget = resolver.Target{ |
| 253 | Scheme: resolver.GetDefaultScheme(), |
| 254 | Endpoint: target, |
| 255 | } |
| 256 | cc.dopts.resolverBuilder = resolver.Get(cc.parsedTarget.Scheme) |
| 257 | } |
| 258 | } else { |
| 259 | cc.parsedTarget = resolver.Target{Endpoint: target} |
| 260 | } |
| 261 | creds := cc.dopts.copts.TransportCredentials |
| 262 | if creds != nil && creds.Info().ServerName != "" { |
| 263 | cc.authority = creds.Info().ServerName |
| 264 | } else if cc.dopts.insecure && cc.dopts.authority != "" { |
| 265 | cc.authority = cc.dopts.authority |
| 266 | } else { |
| 267 | // Use endpoint from "scheme://authority/endpoint" as the default |
| 268 | // authority for ClientConn. |
| 269 | cc.authority = cc.parsedTarget.Endpoint |
| 270 | } |
| 271 | |
| 272 | if cc.dopts.scChan != nil && !scSet { |
| 273 | // Blocking wait for the initial service config. |
| 274 | select { |
| 275 | case sc, ok := <-cc.dopts.scChan: |
| 276 | if ok { |
| 277 | cc.sc = &sc |
| 278 | } |
| 279 | case <-ctx.Done(): |
| 280 | return nil, ctx.Err() |
| 281 | } |
| 282 | } |
| 283 | if cc.dopts.scChan != nil { |
| 284 | go cc.scWatcher() |
| 285 | } |
| 286 | |
| 287 | var credsClone credentials.TransportCredentials |
| 288 | if creds := cc.dopts.copts.TransportCredentials; creds != nil { |
| 289 | credsClone = creds.Clone() |
| 290 | } |
| 291 | cc.balancerBuildOpts = balancer.BuildOptions{ |
| 292 | DialCreds: credsClone, |
| 293 | CredsBundle: cc.dopts.copts.CredsBundle, |
| 294 | Dialer: cc.dopts.copts.Dialer, |
| 295 | ChannelzParentID: cc.channelzID, |
| 296 | Target: cc.parsedTarget, |
| 297 | } |
| 298 | |
| 299 | // Build the resolver. |
| 300 | rWrapper, err := newCCResolverWrapper(cc) |
| 301 | if err != nil { |
| 302 | return nil, fmt.Errorf("failed to build resolver: %v", err) |
| 303 | } |
| 304 | |
| 305 | cc.mu.Lock() |
| 306 | cc.resolverWrapper = rWrapper |
| 307 | cc.mu.Unlock() |
| 308 | // A blocking dial blocks until the clientConn is ready. |
| 309 | if cc.dopts.block { |
| 310 | for { |
| 311 | s := cc.GetState() |
| 312 | if s == connectivity.Ready { |
| 313 | break |
| 314 | } else if cc.dopts.copts.FailOnNonTempDialError && s == connectivity.TransientFailure { |
| 315 | if err = cc.blockingpicker.connectionError(); err != nil { |
| 316 | terr, ok := err.(interface { |
| 317 | Temporary() bool |
| 318 | }) |
| 319 | if ok && !terr.Temporary() { |
| 320 | return nil, err |
| 321 | } |
| 322 | } |
| 323 | } |
| 324 | if !cc.WaitForStateChange(ctx, s) { |
| 325 | // ctx got timeout or canceled. |
| 326 | return nil, ctx.Err() |
| 327 | } |
| 328 | } |
| 329 | } |
| 330 | |
| 331 | return cc, nil |
| 332 | } |
| 333 | |
| 334 | // chainUnaryClientInterceptors chains all unary client interceptors into one. |
| 335 | func chainUnaryClientInterceptors(cc *ClientConn) { |
| 336 | interceptors := cc.dopts.chainUnaryInts |
| 337 | // Prepend dopts.unaryInt to the chaining interceptors if it exists, since unaryInt will |
| 338 | // be executed before any other chained interceptors. |
| 339 | if cc.dopts.unaryInt != nil { |
| 340 | interceptors = append([]UnaryClientInterceptor{cc.dopts.unaryInt}, interceptors...) |
| 341 | } |
| 342 | var chainedInt UnaryClientInterceptor |
| 343 | if len(interceptors) == 0 { |
| 344 | chainedInt = nil |
| 345 | } else if len(interceptors) == 1 { |
| 346 | chainedInt = interceptors[0] |
| 347 | } else { |
| 348 | chainedInt = func(ctx context.Context, method string, req, reply interface{}, cc *ClientConn, invoker UnaryInvoker, opts ...CallOption) error { |
| 349 | return interceptors[0](ctx, method, req, reply, cc, getChainUnaryInvoker(interceptors, 0, invoker), opts...) |
| 350 | } |
| 351 | } |
| 352 | cc.dopts.unaryInt = chainedInt |
| 353 | } |
| 354 | |
| 355 | // getChainUnaryInvoker recursively generate the chained unary invoker. |
| 356 | func getChainUnaryInvoker(interceptors []UnaryClientInterceptor, curr int, finalInvoker UnaryInvoker) UnaryInvoker { |
| 357 | if curr == len(interceptors)-1 { |
| 358 | return finalInvoker |
| 359 | } |
| 360 | return func(ctx context.Context, method string, req, reply interface{}, cc *ClientConn, opts ...CallOption) error { |
| 361 | return interceptors[curr+1](ctx, method, req, reply, cc, getChainUnaryInvoker(interceptors, curr+1, finalInvoker), opts...) |
| 362 | } |
| 363 | } |
| 364 | |
| 365 | // chainStreamClientInterceptors chains all stream client interceptors into one. |
| 366 | func chainStreamClientInterceptors(cc *ClientConn) { |
| 367 | interceptors := cc.dopts.chainStreamInts |
| 368 | // Prepend dopts.streamInt to the chaining interceptors if it exists, since streamInt will |
| 369 | // be executed before any other chained interceptors. |
| 370 | if cc.dopts.streamInt != nil { |
| 371 | interceptors = append([]StreamClientInterceptor{cc.dopts.streamInt}, interceptors...) |
| 372 | } |
| 373 | var chainedInt StreamClientInterceptor |
| 374 | if len(interceptors) == 0 { |
| 375 | chainedInt = nil |
| 376 | } else if len(interceptors) == 1 { |
| 377 | chainedInt = interceptors[0] |
| 378 | } else { |
| 379 | chainedInt = func(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, streamer Streamer, opts ...CallOption) (ClientStream, error) { |
| 380 | return interceptors[0](ctx, desc, cc, method, getChainStreamer(interceptors, 0, streamer), opts...) |
| 381 | } |
| 382 | } |
| 383 | cc.dopts.streamInt = chainedInt |
| 384 | } |
| 385 | |
| 386 | // getChainStreamer recursively generate the chained client stream constructor. |
| 387 | func getChainStreamer(interceptors []StreamClientInterceptor, curr int, finalStreamer Streamer) Streamer { |
| 388 | if curr == len(interceptors)-1 { |
| 389 | return finalStreamer |
| 390 | } |
| 391 | return func(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, opts ...CallOption) (ClientStream, error) { |
| 392 | return interceptors[curr+1](ctx, desc, cc, method, getChainStreamer(interceptors, curr+1, finalStreamer), opts...) |
| 393 | } |
| 394 | } |
| 395 | |
| 396 | // connectivityStateManager keeps the connectivity.State of ClientConn. |
| 397 | // This struct will eventually be exported so the balancers can access it. |
| 398 | type connectivityStateManager struct { |
| 399 | mu sync.Mutex |
| 400 | state connectivity.State |
| 401 | notifyChan chan struct{} |
| 402 | channelzID int64 |
| 403 | } |
| 404 | |
| 405 | // updateState updates the connectivity.State of ClientConn. |
| 406 | // If there's a change it notifies goroutines waiting on state change to |
| 407 | // happen. |
| 408 | func (csm *connectivityStateManager) updateState(state connectivity.State) { |
| 409 | csm.mu.Lock() |
| 410 | defer csm.mu.Unlock() |
| 411 | if csm.state == connectivity.Shutdown { |
| 412 | return |
| 413 | } |
| 414 | if csm.state == state { |
| 415 | return |
| 416 | } |
| 417 | csm.state = state |
| 418 | if channelz.IsOn() { |
| 419 | channelz.AddTraceEvent(csm.channelzID, &channelz.TraceEventDesc{ |
| 420 | Desc: fmt.Sprintf("Channel Connectivity change to %v", state), |
| 421 | Severity: channelz.CtINFO, |
| 422 | }) |
| 423 | } |
| 424 | if csm.notifyChan != nil { |
| 425 | // There are other goroutines waiting on this channel. |
| 426 | close(csm.notifyChan) |
| 427 | csm.notifyChan = nil |
| 428 | } |
| 429 | } |
| 430 | |
| 431 | func (csm *connectivityStateManager) getState() connectivity.State { |
| 432 | csm.mu.Lock() |
| 433 | defer csm.mu.Unlock() |
| 434 | return csm.state |
| 435 | } |
| 436 | |
| 437 | func (csm *connectivityStateManager) getNotifyChan() <-chan struct{} { |
| 438 | csm.mu.Lock() |
| 439 | defer csm.mu.Unlock() |
| 440 | if csm.notifyChan == nil { |
| 441 | csm.notifyChan = make(chan struct{}) |
| 442 | } |
| 443 | return csm.notifyChan |
| 444 | } |
| 445 | |
| 446 | // ClientConn represents a virtual connection to a conceptual endpoint, to |
| 447 | // perform RPCs. |
| 448 | // |
| 449 | // A ClientConn is free to have zero or more actual connections to the endpoint |
| 450 | // based on configuration, load, etc. It is also free to determine which actual |
| 451 | // endpoints to use and may change it every RPC, permitting client-side load |
| 452 | // balancing. |
| 453 | // |
| 454 | // A ClientConn encapsulates a range of functionality including name |
| 455 | // resolution, TCP connection establishment (with retries and backoff) and TLS |
| 456 | // handshakes. It also handles errors on established connections by |
| 457 | // re-resolving the name and reconnecting. |
| 458 | type ClientConn struct { |
| 459 | ctx context.Context |
| 460 | cancel context.CancelFunc |
| 461 | |
| 462 | target string |
| 463 | parsedTarget resolver.Target |
| 464 | authority string |
| 465 | dopts dialOptions |
| 466 | csMgr *connectivityStateManager |
| 467 | |
| 468 | balancerBuildOpts balancer.BuildOptions |
| 469 | blockingpicker *pickerWrapper |
| 470 | |
| 471 | mu sync.RWMutex |
| 472 | resolverWrapper *ccResolverWrapper |
| 473 | sc *ServiceConfig |
| 474 | conns map[*addrConn]struct{} |
| 475 | // Keepalive parameter can be updated if a GoAway is received. |
| 476 | mkp keepalive.ClientParameters |
| 477 | curBalancerName string |
| 478 | balancerWrapper *ccBalancerWrapper |
| 479 | retryThrottler atomic.Value |
| 480 | |
| 481 | firstResolveEvent *grpcsync.Event |
| 482 | |
| 483 | channelzID int64 // channelz unique identification number |
| 484 | czData *channelzData |
| 485 | } |
| 486 | |
| 487 | // WaitForStateChange waits until the connectivity.State of ClientConn changes from sourceState or |
| 488 | // ctx expires. A true value is returned in former case and false in latter. |
| 489 | // This is an EXPERIMENTAL API. |
| 490 | func (cc *ClientConn) WaitForStateChange(ctx context.Context, sourceState connectivity.State) bool { |
| 491 | ch := cc.csMgr.getNotifyChan() |
| 492 | if cc.csMgr.getState() != sourceState { |
| 493 | return true |
| 494 | } |
| 495 | select { |
| 496 | case <-ctx.Done(): |
| 497 | return false |
| 498 | case <-ch: |
| 499 | return true |
| 500 | } |
| 501 | } |
| 502 | |
| 503 | // GetState returns the connectivity.State of ClientConn. |
| 504 | // This is an EXPERIMENTAL API. |
| 505 | func (cc *ClientConn) GetState() connectivity.State { |
| 506 | return cc.csMgr.getState() |
| 507 | } |
| 508 | |
| 509 | func (cc *ClientConn) scWatcher() { |
| 510 | for { |
| 511 | select { |
| 512 | case sc, ok := <-cc.dopts.scChan: |
| 513 | if !ok { |
| 514 | return |
| 515 | } |
| 516 | cc.mu.Lock() |
| 517 | // TODO: load balance policy runtime change is ignored. |
| 518 | // We may revisit this decision in the future. |
| 519 | cc.sc = &sc |
| 520 | cc.mu.Unlock() |
| 521 | case <-cc.ctx.Done(): |
| 522 | return |
| 523 | } |
| 524 | } |
| 525 | } |
| 526 | |
| 527 | // waitForResolvedAddrs blocks until the resolver has provided addresses or the |
| 528 | // context expires. Returns nil unless the context expires first; otherwise |
| 529 | // returns a status error based on the context. |
| 530 | func (cc *ClientConn) waitForResolvedAddrs(ctx context.Context) error { |
| 531 | // This is on the RPC path, so we use a fast path to avoid the |
| 532 | // more-expensive "select" below after the resolver has returned once. |
| 533 | if cc.firstResolveEvent.HasFired() { |
| 534 | return nil |
| 535 | } |
| 536 | select { |
| 537 | case <-cc.firstResolveEvent.Done(): |
| 538 | return nil |
| 539 | case <-ctx.Done(): |
| 540 | return status.FromContextError(ctx.Err()).Err() |
| 541 | case <-cc.ctx.Done(): |
| 542 | return ErrClientConnClosing |
| 543 | } |
| 544 | } |
| 545 | |
| 546 | var emptyServiceConfig *ServiceConfig |
| 547 | |
| 548 | func init() { |
| 549 | cfg := parseServiceConfig("{}") |
| 550 | if cfg.Err != nil { |
| 551 | panic(fmt.Sprintf("impossible error parsing empty service config: %v", cfg.Err)) |
| 552 | } |
| 553 | emptyServiceConfig = cfg.Config.(*ServiceConfig) |
| 554 | } |
| 555 | |
| 556 | func (cc *ClientConn) maybeApplyDefaultServiceConfig(addrs []resolver.Address) { |
| 557 | if cc.sc != nil { |
| 558 | cc.applyServiceConfigAndBalancer(cc.sc, addrs) |
| 559 | return |
| 560 | } |
| 561 | if cc.dopts.defaultServiceConfig != nil { |
| 562 | cc.applyServiceConfigAndBalancer(cc.dopts.defaultServiceConfig, addrs) |
| 563 | } else { |
| 564 | cc.applyServiceConfigAndBalancer(emptyServiceConfig, addrs) |
| 565 | } |
| 566 | } |
| 567 | |
| 568 | func (cc *ClientConn) updateResolverState(s resolver.State, err error) error { |
| 569 | defer cc.firstResolveEvent.Fire() |
| 570 | cc.mu.Lock() |
| 571 | // Check if the ClientConn is already closed. Some fields (e.g. |
| 572 | // balancerWrapper) are set to nil when closing the ClientConn, and could |
| 573 | // cause nil pointer panic if we don't have this check. |
| 574 | if cc.conns == nil { |
| 575 | cc.mu.Unlock() |
| 576 | return nil |
| 577 | } |
| 578 | |
| 579 | if err != nil { |
| 580 | // May need to apply the initial service config in case the resolver |
| 581 | // doesn't support service configs, or doesn't provide a service config |
| 582 | // with the new addresses. |
| 583 | cc.maybeApplyDefaultServiceConfig(nil) |
| 584 | |
| 585 | if cc.balancerWrapper != nil { |
| 586 | cc.balancerWrapper.resolverError(err) |
| 587 | } |
| 588 | |
| 589 | // No addresses are valid with err set; return early. |
| 590 | cc.mu.Unlock() |
| 591 | return balancer.ErrBadResolverState |
| 592 | } |
| 593 | |
| 594 | var ret error |
| 595 | if cc.dopts.disableServiceConfig || s.ServiceConfig == nil { |
| 596 | cc.maybeApplyDefaultServiceConfig(s.Addresses) |
| 597 | // TODO: do we need to apply a failing LB policy if there is no |
| 598 | // default, per the error handling design? |
| 599 | } else { |
| 600 | if sc, ok := s.ServiceConfig.Config.(*ServiceConfig); s.ServiceConfig.Err == nil && ok { |
| 601 | cc.applyServiceConfigAndBalancer(sc, s.Addresses) |
| 602 | } else { |
| 603 | ret = balancer.ErrBadResolverState |
| 604 | if cc.balancerWrapper == nil { |
| 605 | var err error |
| 606 | if s.ServiceConfig.Err != nil { |
| 607 | err = status.Errorf(codes.Unavailable, "error parsing service config: %v", s.ServiceConfig.Err) |
| 608 | } else { |
| 609 | err = status.Errorf(codes.Unavailable, "illegal service config type: %T", s.ServiceConfig.Config) |
| 610 | } |
| 611 | cc.blockingpicker.updatePicker(base.NewErrPicker(err)) |
| 612 | cc.csMgr.updateState(connectivity.TransientFailure) |
| 613 | cc.mu.Unlock() |
| 614 | return ret |
| 615 | } |
| 616 | } |
| 617 | } |
| 618 | |
| 619 | var balCfg serviceconfig.LoadBalancingConfig |
| 620 | if cc.dopts.balancerBuilder == nil && cc.sc != nil && cc.sc.lbConfig != nil { |
| 621 | balCfg = cc.sc.lbConfig.cfg |
| 622 | } |
| 623 | |
| 624 | cbn := cc.curBalancerName |
| 625 | bw := cc.balancerWrapper |
| 626 | cc.mu.Unlock() |
| 627 | if cbn != grpclbName { |
| 628 | // Filter any grpclb addresses since we don't have the grpclb balancer. |
| 629 | for i := 0; i < len(s.Addresses); { |
| 630 | if s.Addresses[i].Type == resolver.GRPCLB { |
| 631 | copy(s.Addresses[i:], s.Addresses[i+1:]) |
| 632 | s.Addresses = s.Addresses[:len(s.Addresses)-1] |
| 633 | continue |
| 634 | } |
| 635 | i++ |
| 636 | } |
| 637 | } |
| 638 | uccsErr := bw.updateClientConnState(&balancer.ClientConnState{ResolverState: s, BalancerConfig: balCfg}) |
| 639 | if ret == nil { |
| 640 | ret = uccsErr // prefer ErrBadResolver state since any other error is |
| 641 | // currently meaningless to the caller. |
| 642 | } |
| 643 | return ret |
| 644 | } |
| 645 | |
| 646 | // switchBalancer starts the switching from current balancer to the balancer |
| 647 | // with the given name. |
| 648 | // |
| 649 | // It will NOT send the current address list to the new balancer. If needed, |
| 650 | // caller of this function should send address list to the new balancer after |
| 651 | // this function returns. |
| 652 | // |
| 653 | // Caller must hold cc.mu. |
| 654 | func (cc *ClientConn) switchBalancer(name string) { |
| 655 | if strings.EqualFold(cc.curBalancerName, name) { |
| 656 | return |
| 657 | } |
| 658 | |
| 659 | grpclog.Infof("ClientConn switching balancer to %q", name) |
| 660 | if cc.dopts.balancerBuilder != nil { |
| 661 | grpclog.Infoln("ignoring balancer switching: Balancer DialOption used instead") |
| 662 | return |
| 663 | } |
| 664 | if cc.balancerWrapper != nil { |
| 665 | cc.balancerWrapper.close() |
| 666 | } |
| 667 | |
| 668 | builder := balancer.Get(name) |
| 669 | if channelz.IsOn() { |
| 670 | if builder == nil { |
| 671 | channelz.AddTraceEvent(cc.channelzID, &channelz.TraceEventDesc{ |
| 672 | Desc: fmt.Sprintf("Channel switches to new LB policy %q due to fallback from invalid balancer name", PickFirstBalancerName), |
| 673 | Severity: channelz.CtWarning, |
| 674 | }) |
| 675 | } else { |
| 676 | channelz.AddTraceEvent(cc.channelzID, &channelz.TraceEventDesc{ |
| 677 | Desc: fmt.Sprintf("Channel switches to new LB policy %q", name), |
| 678 | Severity: channelz.CtINFO, |
| 679 | }) |
| 680 | } |
| 681 | } |
| 682 | if builder == nil { |
| 683 | grpclog.Infof("failed to get balancer builder for: %v, using pick_first instead", name) |
| 684 | builder = newPickfirstBuilder() |
| 685 | } |
| 686 | |
| 687 | cc.curBalancerName = builder.Name() |
| 688 | cc.balancerWrapper = newCCBalancerWrapper(cc, builder, cc.balancerBuildOpts) |
| 689 | } |
| 690 | |
| 691 | func (cc *ClientConn) handleSubConnStateChange(sc balancer.SubConn, s connectivity.State) { |
| 692 | cc.mu.Lock() |
| 693 | if cc.conns == nil { |
| 694 | cc.mu.Unlock() |
| 695 | return |
| 696 | } |
| 697 | // TODO(bar switching) send updates to all balancer wrappers when balancer |
| 698 | // gracefully switching is supported. |
| 699 | cc.balancerWrapper.handleSubConnStateChange(sc, s) |
| 700 | cc.mu.Unlock() |
| 701 | } |
| 702 | |
| 703 | // newAddrConn creates an addrConn for addrs and adds it to cc.conns. |
| 704 | // |
| 705 | // Caller needs to make sure len(addrs) > 0. |
| 706 | func (cc *ClientConn) newAddrConn(addrs []resolver.Address, opts balancer.NewSubConnOptions) (*addrConn, error) { |
| 707 | ac := &addrConn{ |
| 708 | cc: cc, |
| 709 | addrs: addrs, |
| 710 | scopts: opts, |
| 711 | dopts: cc.dopts, |
| 712 | czData: new(channelzData), |
| 713 | resetBackoff: make(chan struct{}), |
| 714 | } |
| 715 | ac.ctx, ac.cancel = context.WithCancel(cc.ctx) |
| 716 | // Track ac in cc. This needs to be done before any getTransport(...) is called. |
| 717 | cc.mu.Lock() |
| 718 | if cc.conns == nil { |
| 719 | cc.mu.Unlock() |
| 720 | return nil, ErrClientConnClosing |
| 721 | } |
| 722 | if channelz.IsOn() { |
| 723 | ac.channelzID = channelz.RegisterSubChannel(ac, cc.channelzID, "") |
| 724 | channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{ |
| 725 | Desc: "Subchannel Created", |
| 726 | Severity: channelz.CtINFO, |
| 727 | Parent: &channelz.TraceEventDesc{ |
| 728 | Desc: fmt.Sprintf("Subchannel(id:%d) created", ac.channelzID), |
| 729 | Severity: channelz.CtINFO, |
| 730 | }, |
| 731 | }) |
| 732 | } |
| 733 | cc.conns[ac] = struct{}{} |
| 734 | cc.mu.Unlock() |
| 735 | return ac, nil |
| 736 | } |
| 737 | |
| 738 | // removeAddrConn removes the addrConn in the subConn from clientConn. |
| 739 | // It also tears down the ac with the given error. |
| 740 | func (cc *ClientConn) removeAddrConn(ac *addrConn, err error) { |
| 741 | cc.mu.Lock() |
| 742 | if cc.conns == nil { |
| 743 | cc.mu.Unlock() |
| 744 | return |
| 745 | } |
| 746 | delete(cc.conns, ac) |
| 747 | cc.mu.Unlock() |
| 748 | ac.tearDown(err) |
| 749 | } |
| 750 | |
| 751 | func (cc *ClientConn) channelzMetric() *channelz.ChannelInternalMetric { |
| 752 | return &channelz.ChannelInternalMetric{ |
| 753 | State: cc.GetState(), |
| 754 | Target: cc.target, |
| 755 | CallsStarted: atomic.LoadInt64(&cc.czData.callsStarted), |
| 756 | CallsSucceeded: atomic.LoadInt64(&cc.czData.callsSucceeded), |
| 757 | CallsFailed: atomic.LoadInt64(&cc.czData.callsFailed), |
| 758 | LastCallStartedTimestamp: time.Unix(0, atomic.LoadInt64(&cc.czData.lastCallStartedTime)), |
| 759 | } |
| 760 | } |
| 761 | |
| 762 | // Target returns the target string of the ClientConn. |
| 763 | // This is an EXPERIMENTAL API. |
| 764 | func (cc *ClientConn) Target() string { |
| 765 | return cc.target |
| 766 | } |
| 767 | |
| 768 | func (cc *ClientConn) incrCallsStarted() { |
| 769 | atomic.AddInt64(&cc.czData.callsStarted, 1) |
| 770 | atomic.StoreInt64(&cc.czData.lastCallStartedTime, time.Now().UnixNano()) |
| 771 | } |
| 772 | |
| 773 | func (cc *ClientConn) incrCallsSucceeded() { |
| 774 | atomic.AddInt64(&cc.czData.callsSucceeded, 1) |
| 775 | } |
| 776 | |
| 777 | func (cc *ClientConn) incrCallsFailed() { |
| 778 | atomic.AddInt64(&cc.czData.callsFailed, 1) |
| 779 | } |
| 780 | |
| 781 | // connect starts creating a transport. |
| 782 | // It does nothing if the ac is not IDLE. |
| 783 | // TODO(bar) Move this to the addrConn section. |
| 784 | func (ac *addrConn) connect() error { |
| 785 | ac.mu.Lock() |
| 786 | if ac.state == connectivity.Shutdown { |
| 787 | ac.mu.Unlock() |
| 788 | return errConnClosing |
| 789 | } |
| 790 | if ac.state != connectivity.Idle { |
| 791 | ac.mu.Unlock() |
| 792 | return nil |
| 793 | } |
| 794 | // Update connectivity state within the lock to prevent subsequent or |
| 795 | // concurrent calls from resetting the transport more than once. |
| 796 | ac.updateConnectivityState(connectivity.Connecting) |
| 797 | ac.mu.Unlock() |
| 798 | |
| 799 | // Start a goroutine connecting to the server asynchronously. |
| 800 | go ac.resetTransport() |
| 801 | return nil |
| 802 | } |
| 803 | |
| 804 | // tryUpdateAddrs tries to update ac.addrs with the new addresses list. |
| 805 | // |
| 806 | // If ac is Connecting, it returns false. The caller should tear down the ac and |
| 807 | // create a new one. Note that the backoff will be reset when this happens. |
| 808 | // |
| 809 | // If ac is TransientFailure, it updates ac.addrs and returns true. The updated |
| 810 | // addresses will be picked up by retry in the next iteration after backoff. |
| 811 | // |
| 812 | // If ac is Shutdown or Idle, it updates ac.addrs and returns true. |
| 813 | // |
| 814 | // If ac is Ready, it checks whether current connected address of ac is in the |
| 815 | // new addrs list. |
| 816 | // - If true, it updates ac.addrs and returns true. The ac will keep using |
| 817 | // the existing connection. |
| 818 | // - If false, it does nothing and returns false. |
| 819 | func (ac *addrConn) tryUpdateAddrs(addrs []resolver.Address) bool { |
| 820 | ac.mu.Lock() |
| 821 | defer ac.mu.Unlock() |
| 822 | grpclog.Infof("addrConn: tryUpdateAddrs curAddr: %v, addrs: %v", ac.curAddr, addrs) |
| 823 | if ac.state == connectivity.Shutdown || |
| 824 | ac.state == connectivity.TransientFailure || |
| 825 | ac.state == connectivity.Idle { |
| 826 | ac.addrs = addrs |
| 827 | return true |
| 828 | } |
| 829 | |
| 830 | if ac.state == connectivity.Connecting { |
| 831 | return false |
| 832 | } |
| 833 | |
| 834 | // ac.state is Ready, try to find the connected address. |
| 835 | var curAddrFound bool |
| 836 | for _, a := range addrs { |
| 837 | if reflect.DeepEqual(ac.curAddr, a) { |
| 838 | curAddrFound = true |
| 839 | break |
| 840 | } |
| 841 | } |
| 842 | grpclog.Infof("addrConn: tryUpdateAddrs curAddrFound: %v", curAddrFound) |
| 843 | if curAddrFound { |
| 844 | ac.addrs = addrs |
| 845 | } |
| 846 | |
| 847 | return curAddrFound |
| 848 | } |
| 849 | |
| 850 | // GetMethodConfig gets the method config of the input method. |
| 851 | // If there's an exact match for input method (i.e. /service/method), we return |
| 852 | // the corresponding MethodConfig. |
| 853 | // If there isn't an exact match for the input method, we look for the default config |
| 854 | // under the service (i.e /service/). If there is a default MethodConfig for |
| 855 | // the service, we return it. |
| 856 | // Otherwise, we return an empty MethodConfig. |
| 857 | func (cc *ClientConn) GetMethodConfig(method string) MethodConfig { |
| 858 | // TODO: Avoid the locking here. |
| 859 | cc.mu.RLock() |
| 860 | defer cc.mu.RUnlock() |
| 861 | if cc.sc == nil { |
| 862 | return MethodConfig{} |
| 863 | } |
| 864 | m, ok := cc.sc.Methods[method] |
| 865 | if !ok { |
| 866 | i := strings.LastIndex(method, "/") |
| 867 | m = cc.sc.Methods[method[:i+1]] |
| 868 | } |
| 869 | return m |
| 870 | } |
| 871 | |
| 872 | func (cc *ClientConn) healthCheckConfig() *healthCheckConfig { |
| 873 | cc.mu.RLock() |
| 874 | defer cc.mu.RUnlock() |
| 875 | if cc.sc == nil { |
| 876 | return nil |
| 877 | } |
| 878 | return cc.sc.healthCheckConfig |
| 879 | } |
| 880 | |
| 881 | func (cc *ClientConn) getTransport(ctx context.Context, failfast bool, method string) (transport.ClientTransport, func(balancer.DoneInfo), error) { |
| 882 | t, done, err := cc.blockingpicker.pick(ctx, failfast, balancer.PickOptions{ |
| 883 | FullMethodName: method, |
| 884 | }) |
| 885 | if err != nil { |
| 886 | return nil, nil, toRPCErr(err) |
| 887 | } |
| 888 | return t, done, nil |
| 889 | } |
| 890 | |
| 891 | func (cc *ClientConn) applyServiceConfigAndBalancer(sc *ServiceConfig, addrs []resolver.Address) { |
| 892 | if sc == nil { |
| 893 | // should never reach here. |
| 894 | return |
| 895 | } |
| 896 | cc.sc = sc |
| 897 | |
| 898 | if cc.sc.retryThrottling != nil { |
| 899 | newThrottler := &retryThrottler{ |
| 900 | tokens: cc.sc.retryThrottling.MaxTokens, |
| 901 | max: cc.sc.retryThrottling.MaxTokens, |
| 902 | thresh: cc.sc.retryThrottling.MaxTokens / 2, |
| 903 | ratio: cc.sc.retryThrottling.TokenRatio, |
| 904 | } |
| 905 | cc.retryThrottler.Store(newThrottler) |
| 906 | } else { |
| 907 | cc.retryThrottler.Store((*retryThrottler)(nil)) |
| 908 | } |
| 909 | |
| 910 | if cc.dopts.balancerBuilder == nil { |
| 911 | // Only look at balancer types and switch balancer if balancer dial |
| 912 | // option is not set. |
| 913 | var newBalancerName string |
| 914 | if cc.sc != nil && cc.sc.lbConfig != nil { |
| 915 | newBalancerName = cc.sc.lbConfig.name |
| 916 | } else { |
| 917 | var isGRPCLB bool |
| 918 | for _, a := range addrs { |
| 919 | if a.Type == resolver.GRPCLB { |
| 920 | isGRPCLB = true |
| 921 | break |
| 922 | } |
| 923 | } |
| 924 | if isGRPCLB { |
| 925 | newBalancerName = grpclbName |
| 926 | } else if cc.sc != nil && cc.sc.LB != nil { |
| 927 | newBalancerName = *cc.sc.LB |
| 928 | } else { |
| 929 | newBalancerName = PickFirstBalancerName |
| 930 | } |
| 931 | } |
| 932 | cc.switchBalancer(newBalancerName) |
| 933 | } else if cc.balancerWrapper == nil { |
| 934 | // Balancer dial option was set, and this is the first time handling |
| 935 | // resolved addresses. Build a balancer with dopts.balancerBuilder. |
| 936 | cc.curBalancerName = cc.dopts.balancerBuilder.Name() |
| 937 | cc.balancerWrapper = newCCBalancerWrapper(cc, cc.dopts.balancerBuilder, cc.balancerBuildOpts) |
| 938 | } |
| 939 | } |
| 940 | |
| 941 | func (cc *ClientConn) resolveNow(o resolver.ResolveNowOption) { |
| 942 | cc.mu.RLock() |
| 943 | r := cc.resolverWrapper |
| 944 | cc.mu.RUnlock() |
| 945 | if r == nil { |
| 946 | return |
| 947 | } |
| 948 | go r.resolveNow(o) |
| 949 | } |
| 950 | |
| 951 | // ResetConnectBackoff wakes up all subchannels in transient failure and causes |
| 952 | // them to attempt another connection immediately. It also resets the backoff |
| 953 | // times used for subsequent attempts regardless of the current state. |
| 954 | // |
| 955 | // In general, this function should not be used. Typical service or network |
| 956 | // outages result in a reasonable client reconnection strategy by default. |
| 957 | // However, if a previously unavailable network becomes available, this may be |
| 958 | // used to trigger an immediate reconnect. |
| 959 | // |
| 960 | // This API is EXPERIMENTAL. |
| 961 | func (cc *ClientConn) ResetConnectBackoff() { |
| 962 | cc.mu.Lock() |
| 963 | conns := cc.conns |
| 964 | cc.mu.Unlock() |
| 965 | for ac := range conns { |
| 966 | ac.resetConnectBackoff() |
| 967 | } |
| 968 | } |
| 969 | |
| 970 | // Close tears down the ClientConn and all underlying connections. |
| 971 | func (cc *ClientConn) Close() error { |
| 972 | defer cc.cancel() |
| 973 | |
| 974 | cc.mu.Lock() |
| 975 | if cc.conns == nil { |
| 976 | cc.mu.Unlock() |
| 977 | return ErrClientConnClosing |
| 978 | } |
| 979 | conns := cc.conns |
| 980 | cc.conns = nil |
| 981 | cc.csMgr.updateState(connectivity.Shutdown) |
| 982 | |
| 983 | rWrapper := cc.resolverWrapper |
| 984 | cc.resolverWrapper = nil |
| 985 | bWrapper := cc.balancerWrapper |
| 986 | cc.balancerWrapper = nil |
| 987 | cc.mu.Unlock() |
| 988 | |
| 989 | cc.blockingpicker.close() |
| 990 | |
| 991 | if rWrapper != nil { |
| 992 | rWrapper.close() |
| 993 | } |
| 994 | if bWrapper != nil { |
| 995 | bWrapper.close() |
| 996 | } |
| 997 | |
| 998 | for ac := range conns { |
| 999 | ac.tearDown(ErrClientConnClosing) |
| 1000 | } |
| 1001 | if channelz.IsOn() { |
| 1002 | ted := &channelz.TraceEventDesc{ |
| 1003 | Desc: "Channel Deleted", |
| 1004 | Severity: channelz.CtINFO, |
| 1005 | } |
| 1006 | if cc.dopts.channelzParentID != 0 { |
| 1007 | ted.Parent = &channelz.TraceEventDesc{ |
| 1008 | Desc: fmt.Sprintf("Nested channel(id:%d) deleted", cc.channelzID), |
| 1009 | Severity: channelz.CtINFO, |
| 1010 | } |
| 1011 | } |
| 1012 | channelz.AddTraceEvent(cc.channelzID, ted) |
| 1013 | // TraceEvent needs to be called before RemoveEntry, as TraceEvent may add trace reference to |
| 1014 | // the entity being deleted, and thus prevent it from being deleted right away. |
| 1015 | channelz.RemoveEntry(cc.channelzID) |
| 1016 | } |
| 1017 | return nil |
| 1018 | } |
| 1019 | |
| 1020 | // addrConn is a network connection to a given address. |
| 1021 | type addrConn struct { |
| 1022 | ctx context.Context |
| 1023 | cancel context.CancelFunc |
| 1024 | |
| 1025 | cc *ClientConn |
| 1026 | dopts dialOptions |
| 1027 | acbw balancer.SubConn |
| 1028 | scopts balancer.NewSubConnOptions |
| 1029 | |
| 1030 | // transport is set when there's a viable transport (note: ac state may not be READY as LB channel |
| 1031 | // health checking may require server to report healthy to set ac to READY), and is reset |
| 1032 | // to nil when the current transport should no longer be used to create a stream (e.g. after GoAway |
| 1033 | // is received, transport is closed, ac has been torn down). |
| 1034 | transport transport.ClientTransport // The current transport. |
| 1035 | |
| 1036 | mu sync.Mutex |
| 1037 | curAddr resolver.Address // The current address. |
| 1038 | addrs []resolver.Address // All addresses that the resolver resolved to. |
| 1039 | |
| 1040 | // Use updateConnectivityState for updating addrConn's connectivity state. |
| 1041 | state connectivity.State |
| 1042 | |
| 1043 | backoffIdx int // Needs to be stateful for resetConnectBackoff. |
| 1044 | resetBackoff chan struct{} |
| 1045 | |
| 1046 | channelzID int64 // channelz unique identification number. |
| 1047 | czData *channelzData |
| 1048 | } |
| 1049 | |
| 1050 | // Note: this requires a lock on ac.mu. |
| 1051 | func (ac *addrConn) updateConnectivityState(s connectivity.State) { |
| 1052 | if ac.state == s { |
| 1053 | return |
| 1054 | } |
| 1055 | |
| 1056 | updateMsg := fmt.Sprintf("Subchannel Connectivity change to %v", s) |
| 1057 | ac.state = s |
| 1058 | if channelz.IsOn() { |
| 1059 | channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{ |
| 1060 | Desc: updateMsg, |
| 1061 | Severity: channelz.CtINFO, |
| 1062 | }) |
| 1063 | } |
| 1064 | ac.cc.handleSubConnStateChange(ac.acbw, s) |
| 1065 | } |
| 1066 | |
| 1067 | // adjustParams updates parameters used to create transports upon |
| 1068 | // receiving a GoAway. |
| 1069 | func (ac *addrConn) adjustParams(r transport.GoAwayReason) { |
| 1070 | switch r { |
| 1071 | case transport.GoAwayTooManyPings: |
| 1072 | v := 2 * ac.dopts.copts.KeepaliveParams.Time |
| 1073 | ac.cc.mu.Lock() |
| 1074 | if v > ac.cc.mkp.Time { |
| 1075 | ac.cc.mkp.Time = v |
| 1076 | } |
| 1077 | ac.cc.mu.Unlock() |
| 1078 | } |
| 1079 | } |
| 1080 | |
| 1081 | func (ac *addrConn) resetTransport() { |
| 1082 | for i := 0; ; i++ { |
| 1083 | if i > 0 { |
| 1084 | ac.cc.resolveNow(resolver.ResolveNowOption{}) |
| 1085 | } |
| 1086 | |
| 1087 | ac.mu.Lock() |
| 1088 | if ac.state == connectivity.Shutdown { |
| 1089 | ac.mu.Unlock() |
| 1090 | return |
| 1091 | } |
| 1092 | |
| 1093 | addrs := ac.addrs |
| 1094 | backoffFor := ac.dopts.bs.Backoff(ac.backoffIdx) |
| 1095 | // This will be the duration that dial gets to finish. |
| 1096 | dialDuration := minConnectTimeout |
| 1097 | if ac.dopts.minConnectTimeout != nil { |
| 1098 | dialDuration = ac.dopts.minConnectTimeout() |
| 1099 | } |
| 1100 | |
| 1101 | if dialDuration < backoffFor { |
| 1102 | // Give dial more time as we keep failing to connect. |
| 1103 | dialDuration = backoffFor |
| 1104 | } |
| 1105 | // We can potentially spend all the time trying the first address, and |
| 1106 | // if the server accepts the connection and then hangs, the following |
| 1107 | // addresses will never be tried. |
| 1108 | // |
| 1109 | // The spec doesn't mention what should be done for multiple addresses. |
| 1110 | // https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md#proposed-backoff-algorithm |
| 1111 | connectDeadline := time.Now().Add(dialDuration) |
| 1112 | |
| 1113 | ac.updateConnectivityState(connectivity.Connecting) |
| 1114 | ac.transport = nil |
| 1115 | ac.mu.Unlock() |
| 1116 | |
| 1117 | newTr, addr, reconnect, err := ac.tryAllAddrs(addrs, connectDeadline) |
| 1118 | if err != nil { |
| 1119 | // After exhausting all addresses, the addrConn enters |
| 1120 | // TRANSIENT_FAILURE. |
| 1121 | ac.mu.Lock() |
| 1122 | if ac.state == connectivity.Shutdown { |
| 1123 | ac.mu.Unlock() |
| 1124 | return |
| 1125 | } |
| 1126 | ac.updateConnectivityState(connectivity.TransientFailure) |
| 1127 | |
| 1128 | // Backoff. |
| 1129 | b := ac.resetBackoff |
| 1130 | ac.mu.Unlock() |
| 1131 | |
| 1132 | timer := time.NewTimer(backoffFor) |
| 1133 | select { |
| 1134 | case <-timer.C: |
| 1135 | ac.mu.Lock() |
| 1136 | ac.backoffIdx++ |
| 1137 | ac.mu.Unlock() |
| 1138 | case <-b: |
| 1139 | timer.Stop() |
| 1140 | case <-ac.ctx.Done(): |
| 1141 | timer.Stop() |
| 1142 | return |
| 1143 | } |
| 1144 | continue |
| 1145 | } |
| 1146 | |
| 1147 | ac.mu.Lock() |
| 1148 | if ac.state == connectivity.Shutdown { |
| 1149 | ac.mu.Unlock() |
| 1150 | newTr.Close() |
| 1151 | return |
| 1152 | } |
| 1153 | ac.curAddr = addr |
| 1154 | ac.transport = newTr |
| 1155 | ac.backoffIdx = 0 |
| 1156 | |
| 1157 | hctx, hcancel := context.WithCancel(ac.ctx) |
| 1158 | ac.startHealthCheck(hctx) |
| 1159 | ac.mu.Unlock() |
| 1160 | |
| 1161 | // Block until the created transport is down. And when this happens, |
| 1162 | // we restart from the top of the addr list. |
| 1163 | <-reconnect.Done() |
| 1164 | hcancel() |
| 1165 | // restart connecting - the top of the loop will set state to |
| 1166 | // CONNECTING. This is against the current connectivity semantics doc, |
| 1167 | // however it allows for graceful behavior for RPCs not yet dispatched |
| 1168 | // - unfortunate timing would otherwise lead to the RPC failing even |
| 1169 | // though the TRANSIENT_FAILURE state (called for by the doc) would be |
| 1170 | // instantaneous. |
| 1171 | // |
| 1172 | // Ideally we should transition to Idle here and block until there is |
| 1173 | // RPC activity that leads to the balancer requesting a reconnect of |
| 1174 | // the associated SubConn. |
| 1175 | } |
| 1176 | } |
| 1177 | |
| 1178 | // tryAllAddrs tries to creates a connection to the addresses, and stop when at the |
| 1179 | // first successful one. It returns the transport, the address and a Event in |
| 1180 | // the successful case. The Event fires when the returned transport disconnects. |
| 1181 | func (ac *addrConn) tryAllAddrs(addrs []resolver.Address, connectDeadline time.Time) (transport.ClientTransport, resolver.Address, *grpcsync.Event, error) { |
| 1182 | for _, addr := range addrs { |
| 1183 | ac.mu.Lock() |
| 1184 | if ac.state == connectivity.Shutdown { |
| 1185 | ac.mu.Unlock() |
| 1186 | return nil, resolver.Address{}, nil, errConnClosing |
| 1187 | } |
| 1188 | |
| 1189 | ac.cc.mu.RLock() |
| 1190 | ac.dopts.copts.KeepaliveParams = ac.cc.mkp |
| 1191 | ac.cc.mu.RUnlock() |
| 1192 | |
| 1193 | copts := ac.dopts.copts |
| 1194 | if ac.scopts.CredsBundle != nil { |
| 1195 | copts.CredsBundle = ac.scopts.CredsBundle |
| 1196 | } |
| 1197 | ac.mu.Unlock() |
| 1198 | |
| 1199 | if channelz.IsOn() { |
| 1200 | channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{ |
| 1201 | Desc: fmt.Sprintf("Subchannel picks a new address %q to connect", addr.Addr), |
| 1202 | Severity: channelz.CtINFO, |
| 1203 | }) |
| 1204 | } |
| 1205 | |
| 1206 | newTr, reconnect, err := ac.createTransport(addr, copts, connectDeadline) |
| 1207 | if err == nil { |
| 1208 | return newTr, addr, reconnect, nil |
| 1209 | } |
| 1210 | ac.cc.blockingpicker.updateConnectionError(err) |
| 1211 | } |
| 1212 | |
| 1213 | // Couldn't connect to any address. |
| 1214 | return nil, resolver.Address{}, nil, fmt.Errorf("couldn't connect to any address") |
| 1215 | } |
| 1216 | |
| 1217 | // createTransport creates a connection to addr. It returns the transport and a |
| 1218 | // Event in the successful case. The Event fires when the returned transport |
| 1219 | // disconnects. |
| 1220 | func (ac *addrConn) createTransport(addr resolver.Address, copts transport.ConnectOptions, connectDeadline time.Time) (transport.ClientTransport, *grpcsync.Event, error) { |
| 1221 | prefaceReceived := make(chan struct{}) |
| 1222 | onCloseCalled := make(chan struct{}) |
| 1223 | reconnect := grpcsync.NewEvent() |
| 1224 | |
| 1225 | authority := ac.cc.authority |
| 1226 | // addr.ServerName takes precedent over ClientConn authority, if present. |
| 1227 | if addr.ServerName != "" { |
| 1228 | authority = addr.ServerName |
| 1229 | } |
| 1230 | |
| 1231 | target := transport.TargetInfo{ |
| 1232 | Addr: addr.Addr, |
| 1233 | Metadata: addr.Metadata, |
| 1234 | Authority: authority, |
| 1235 | } |
| 1236 | |
| 1237 | once := sync.Once{} |
| 1238 | onGoAway := func(r transport.GoAwayReason) { |
| 1239 | ac.mu.Lock() |
| 1240 | ac.adjustParams(r) |
| 1241 | once.Do(func() { |
| 1242 | if ac.state == connectivity.Ready { |
| 1243 | // Prevent this SubConn from being used for new RPCs by setting its |
| 1244 | // state to Connecting. |
| 1245 | // |
| 1246 | // TODO: this should be Idle when grpc-go properly supports it. |
| 1247 | ac.updateConnectivityState(connectivity.Connecting) |
| 1248 | } |
| 1249 | }) |
| 1250 | ac.mu.Unlock() |
| 1251 | reconnect.Fire() |
| 1252 | } |
| 1253 | |
| 1254 | onClose := func() { |
| 1255 | ac.mu.Lock() |
| 1256 | once.Do(func() { |
| 1257 | if ac.state == connectivity.Ready { |
| 1258 | // Prevent this SubConn from being used for new RPCs by setting its |
| 1259 | // state to Connecting. |
| 1260 | // |
| 1261 | // TODO: this should be Idle when grpc-go properly supports it. |
| 1262 | ac.updateConnectivityState(connectivity.Connecting) |
| 1263 | } |
| 1264 | }) |
| 1265 | ac.mu.Unlock() |
| 1266 | close(onCloseCalled) |
| 1267 | reconnect.Fire() |
| 1268 | } |
| 1269 | |
| 1270 | onPrefaceReceipt := func() { |
| 1271 | close(prefaceReceived) |
| 1272 | } |
| 1273 | |
| 1274 | connectCtx, cancel := context.WithDeadline(ac.ctx, connectDeadline) |
| 1275 | defer cancel() |
| 1276 | if channelz.IsOn() { |
| 1277 | copts.ChannelzParentID = ac.channelzID |
| 1278 | } |
| 1279 | |
| 1280 | newTr, err := transport.NewClientTransport(connectCtx, ac.cc.ctx, target, copts, onPrefaceReceipt, onGoAway, onClose) |
| 1281 | if err != nil { |
| 1282 | // newTr is either nil, or closed. |
| 1283 | grpclog.Warningf("grpc: addrConn.createTransport failed to connect to %v. Err :%v. Reconnecting...", addr, err) |
| 1284 | return nil, nil, err |
| 1285 | } |
| 1286 | |
| 1287 | select { |
| 1288 | case <-time.After(connectDeadline.Sub(time.Now())): |
| 1289 | // We didn't get the preface in time. |
| 1290 | newTr.Close() |
| 1291 | grpclog.Warningf("grpc: addrConn.createTransport failed to connect to %v: didn't receive server preface in time. Reconnecting...", addr) |
| 1292 | return nil, nil, errors.New("timed out waiting for server handshake") |
| 1293 | case <-prefaceReceived: |
| 1294 | // We got the preface - huzzah! things are good. |
| 1295 | case <-onCloseCalled: |
| 1296 | // The transport has already closed - noop. |
| 1297 | return nil, nil, errors.New("connection closed") |
| 1298 | // TODO(deklerk) this should bail on ac.ctx.Done(). Add a test and fix. |
| 1299 | } |
| 1300 | return newTr, reconnect, nil |
| 1301 | } |
| 1302 | |
| 1303 | // startHealthCheck starts the health checking stream (RPC) to watch the health |
| 1304 | // stats of this connection if health checking is requested and configured. |
| 1305 | // |
| 1306 | // LB channel health checking is enabled when all requirements below are met: |
| 1307 | // 1. it is not disabled by the user with the WithDisableHealthCheck DialOption |
| 1308 | // 2. internal.HealthCheckFunc is set by importing the grpc/healthcheck package |
| 1309 | // 3. a service config with non-empty healthCheckConfig field is provided |
| 1310 | // 4. the load balancer requests it |
| 1311 | // |
| 1312 | // It sets addrConn to READY if the health checking stream is not started. |
| 1313 | // |
| 1314 | // Caller must hold ac.mu. |
| 1315 | func (ac *addrConn) startHealthCheck(ctx context.Context) { |
| 1316 | var healthcheckManagingState bool |
| 1317 | defer func() { |
| 1318 | if !healthcheckManagingState { |
| 1319 | ac.updateConnectivityState(connectivity.Ready) |
| 1320 | } |
| 1321 | }() |
| 1322 | |
| 1323 | if ac.cc.dopts.disableHealthCheck { |
| 1324 | return |
| 1325 | } |
| 1326 | healthCheckConfig := ac.cc.healthCheckConfig() |
| 1327 | if healthCheckConfig == nil { |
| 1328 | return |
| 1329 | } |
| 1330 | if !ac.scopts.HealthCheckEnabled { |
| 1331 | return |
| 1332 | } |
| 1333 | healthCheckFunc := ac.cc.dopts.healthCheckFunc |
| 1334 | if healthCheckFunc == nil { |
| 1335 | // The health package is not imported to set health check function. |
| 1336 | // |
| 1337 | // TODO: add a link to the health check doc in the error message. |
| 1338 | grpclog.Error("Health check is requested but health check function is not set.") |
| 1339 | return |
| 1340 | } |
| 1341 | |
| 1342 | healthcheckManagingState = true |
| 1343 | |
| 1344 | // Set up the health check helper functions. |
| 1345 | currentTr := ac.transport |
| 1346 | newStream := func(method string) (interface{}, error) { |
| 1347 | ac.mu.Lock() |
| 1348 | if ac.transport != currentTr { |
| 1349 | ac.mu.Unlock() |
| 1350 | return nil, status.Error(codes.Canceled, "the provided transport is no longer valid to use") |
| 1351 | } |
| 1352 | ac.mu.Unlock() |
| 1353 | return newNonRetryClientStream(ctx, &StreamDesc{ServerStreams: true}, method, currentTr, ac) |
| 1354 | } |
| 1355 | setConnectivityState := func(s connectivity.State) { |
| 1356 | ac.mu.Lock() |
| 1357 | defer ac.mu.Unlock() |
| 1358 | if ac.transport != currentTr { |
| 1359 | return |
| 1360 | } |
| 1361 | ac.updateConnectivityState(s) |
| 1362 | } |
| 1363 | // Start the health checking stream. |
| 1364 | go func() { |
| 1365 | err := ac.cc.dopts.healthCheckFunc(ctx, newStream, setConnectivityState, healthCheckConfig.ServiceName) |
| 1366 | if err != nil { |
| 1367 | if status.Code(err) == codes.Unimplemented { |
| 1368 | if channelz.IsOn() { |
| 1369 | channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{ |
| 1370 | Desc: "Subchannel health check is unimplemented at server side, thus health check is disabled", |
| 1371 | Severity: channelz.CtError, |
| 1372 | }) |
| 1373 | } |
| 1374 | grpclog.Error("Subchannel health check is unimplemented at server side, thus health check is disabled") |
| 1375 | } else { |
| 1376 | grpclog.Errorf("HealthCheckFunc exits with unexpected error %v", err) |
| 1377 | } |
| 1378 | } |
| 1379 | }() |
| 1380 | } |
| 1381 | |
| 1382 | func (ac *addrConn) resetConnectBackoff() { |
| 1383 | ac.mu.Lock() |
| 1384 | close(ac.resetBackoff) |
| 1385 | ac.backoffIdx = 0 |
| 1386 | ac.resetBackoff = make(chan struct{}) |
| 1387 | ac.mu.Unlock() |
| 1388 | } |
| 1389 | |
| 1390 | // getReadyTransport returns the transport if ac's state is READY. |
| 1391 | // Otherwise it returns nil, false. |
| 1392 | // If ac's state is IDLE, it will trigger ac to connect. |
| 1393 | func (ac *addrConn) getReadyTransport() (transport.ClientTransport, bool) { |
| 1394 | ac.mu.Lock() |
| 1395 | if ac.state == connectivity.Ready && ac.transport != nil { |
| 1396 | t := ac.transport |
| 1397 | ac.mu.Unlock() |
| 1398 | return t, true |
| 1399 | } |
| 1400 | var idle bool |
| 1401 | if ac.state == connectivity.Idle { |
| 1402 | idle = true |
| 1403 | } |
| 1404 | ac.mu.Unlock() |
| 1405 | // Trigger idle ac to connect. |
| 1406 | if idle { |
| 1407 | ac.connect() |
| 1408 | } |
| 1409 | return nil, false |
| 1410 | } |
| 1411 | |
| 1412 | // tearDown starts to tear down the addrConn. |
| 1413 | // TODO(zhaoq): Make this synchronous to avoid unbounded memory consumption in |
| 1414 | // some edge cases (e.g., the caller opens and closes many addrConn's in a |
| 1415 | // tight loop. |
| 1416 | // tearDown doesn't remove ac from ac.cc.conns. |
| 1417 | func (ac *addrConn) tearDown(err error) { |
| 1418 | ac.mu.Lock() |
| 1419 | if ac.state == connectivity.Shutdown { |
| 1420 | ac.mu.Unlock() |
| 1421 | return |
| 1422 | } |
| 1423 | curTr := ac.transport |
| 1424 | ac.transport = nil |
| 1425 | // We have to set the state to Shutdown before anything else to prevent races |
| 1426 | // between setting the state and logic that waits on context cancellation / etc. |
| 1427 | ac.updateConnectivityState(connectivity.Shutdown) |
| 1428 | ac.cancel() |
| 1429 | ac.curAddr = resolver.Address{} |
| 1430 | if err == errConnDrain && curTr != nil { |
| 1431 | // GracefulClose(...) may be executed multiple times when |
| 1432 | // i) receiving multiple GoAway frames from the server; or |
| 1433 | // ii) there are concurrent name resolver/Balancer triggered |
| 1434 | // address removal and GoAway. |
| 1435 | // We have to unlock and re-lock here because GracefulClose => Close => onClose, which requires locking ac.mu. |
| 1436 | ac.mu.Unlock() |
| 1437 | curTr.GracefulClose() |
| 1438 | ac.mu.Lock() |
| 1439 | } |
| 1440 | if channelz.IsOn() { |
| 1441 | channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{ |
| 1442 | Desc: "Subchannel Deleted", |
| 1443 | Severity: channelz.CtINFO, |
| 1444 | Parent: &channelz.TraceEventDesc{ |
| 1445 | Desc: fmt.Sprintf("Subchanel(id:%d) deleted", ac.channelzID), |
| 1446 | Severity: channelz.CtINFO, |
| 1447 | }, |
| 1448 | }) |
| 1449 | // TraceEvent needs to be called before RemoveEntry, as TraceEvent may add trace reference to |
| 1450 | // the entity being deleted, and thus prevent it from being deleted right away. |
| 1451 | channelz.RemoveEntry(ac.channelzID) |
| 1452 | } |
| 1453 | ac.mu.Unlock() |
| 1454 | } |
| 1455 | |
| 1456 | func (ac *addrConn) getState() connectivity.State { |
| 1457 | ac.mu.Lock() |
| 1458 | defer ac.mu.Unlock() |
| 1459 | return ac.state |
| 1460 | } |
| 1461 | |
| 1462 | func (ac *addrConn) ChannelzMetric() *channelz.ChannelInternalMetric { |
| 1463 | ac.mu.Lock() |
| 1464 | addr := ac.curAddr.Addr |
| 1465 | ac.mu.Unlock() |
| 1466 | return &channelz.ChannelInternalMetric{ |
| 1467 | State: ac.getState(), |
| 1468 | Target: addr, |
| 1469 | CallsStarted: atomic.LoadInt64(&ac.czData.callsStarted), |
| 1470 | CallsSucceeded: atomic.LoadInt64(&ac.czData.callsSucceeded), |
| 1471 | CallsFailed: atomic.LoadInt64(&ac.czData.callsFailed), |
| 1472 | LastCallStartedTimestamp: time.Unix(0, atomic.LoadInt64(&ac.czData.lastCallStartedTime)), |
| 1473 | } |
| 1474 | } |
| 1475 | |
| 1476 | func (ac *addrConn) incrCallsStarted() { |
| 1477 | atomic.AddInt64(&ac.czData.callsStarted, 1) |
| 1478 | atomic.StoreInt64(&ac.czData.lastCallStartedTime, time.Now().UnixNano()) |
| 1479 | } |
| 1480 | |
| 1481 | func (ac *addrConn) incrCallsSucceeded() { |
| 1482 | atomic.AddInt64(&ac.czData.callsSucceeded, 1) |
| 1483 | } |
| 1484 | |
| 1485 | func (ac *addrConn) incrCallsFailed() { |
| 1486 | atomic.AddInt64(&ac.czData.callsFailed, 1) |
| 1487 | } |
| 1488 | |
| 1489 | type retryThrottler struct { |
| 1490 | max float64 |
| 1491 | thresh float64 |
| 1492 | ratio float64 |
| 1493 | |
| 1494 | mu sync.Mutex |
| 1495 | tokens float64 // TODO(dfawley): replace with atomic and remove lock. |
| 1496 | } |
| 1497 | |
| 1498 | // throttle subtracts a retry token from the pool and returns whether a retry |
| 1499 | // should be throttled (disallowed) based upon the retry throttling policy in |
| 1500 | // the service config. |
| 1501 | func (rt *retryThrottler) throttle() bool { |
| 1502 | if rt == nil { |
| 1503 | return false |
| 1504 | } |
| 1505 | rt.mu.Lock() |
| 1506 | defer rt.mu.Unlock() |
| 1507 | rt.tokens-- |
| 1508 | if rt.tokens < 0 { |
| 1509 | rt.tokens = 0 |
| 1510 | } |
| 1511 | return rt.tokens <= rt.thresh |
| 1512 | } |
| 1513 | |
| 1514 | func (rt *retryThrottler) successfulRPC() { |
| 1515 | if rt == nil { |
| 1516 | return |
| 1517 | } |
| 1518 | rt.mu.Lock() |
| 1519 | defer rt.mu.Unlock() |
| 1520 | rt.tokens += rt.ratio |
| 1521 | if rt.tokens > rt.max { |
| 1522 | rt.tokens = rt.max |
| 1523 | } |
| 1524 | } |
| 1525 | |
| 1526 | type channelzChannel struct { |
| 1527 | cc *ClientConn |
| 1528 | } |
| 1529 | |
| 1530 | func (c *channelzChannel) ChannelzMetric() *channelz.ChannelInternalMetric { |
| 1531 | return c.cc.channelzMetric() |
| 1532 | } |
| 1533 | |
| 1534 | // ErrClientConnTimeout indicates that the ClientConn cannot establish the |
| 1535 | // underlying connections within the specified timeout. |
| 1536 | // |
| 1537 | // Deprecated: This error is never returned by grpc and should not be |
| 1538 | // referenced by users. |
| 1539 | var ErrClientConnTimeout = errors.New("grpc: timed out when dialing") |