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Diffstat (limited to 'vendor/google.golang.org/grpc/balancer/pickfirst/pickfirstleaf/pickfirstleaf.go')
| -rw-r--r-- | vendor/google.golang.org/grpc/balancer/pickfirst/pickfirstleaf/pickfirstleaf.go | 911 |
1 files changed, 911 insertions, 0 deletions
diff --git a/vendor/google.golang.org/grpc/balancer/pickfirst/pickfirstleaf/pickfirstleaf.go b/vendor/google.golang.org/grpc/balancer/pickfirst/pickfirstleaf/pickfirstleaf.go new file mode 100644 index 000000000..2fc0a71f9 --- /dev/null +++ b/vendor/google.golang.org/grpc/balancer/pickfirst/pickfirstleaf/pickfirstleaf.go @@ -0,0 +1,911 @@ +/* + * + * Copyright 2024 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 pickfirstleaf contains the pick_first load balancing policy which +// will be the universal leaf policy after dualstack changes are implemented. +// +// # Experimental +// +// Notice: This package is EXPERIMENTAL and may be changed or removed in a +// later release. +package pickfirstleaf + +import ( + "encoding/json" + "errors" + "fmt" + "net" + "net/netip" + "sync" + "time" + + "google.golang.org/grpc/balancer" + "google.golang.org/grpc/balancer/pickfirst/internal" + "google.golang.org/grpc/connectivity" + expstats "google.golang.org/grpc/experimental/stats" + "google.golang.org/grpc/grpclog" + "google.golang.org/grpc/internal/envconfig" + internalgrpclog "google.golang.org/grpc/internal/grpclog" + "google.golang.org/grpc/internal/pretty" + "google.golang.org/grpc/resolver" + "google.golang.org/grpc/serviceconfig" +) + +func init() { + if envconfig.NewPickFirstEnabled { + // Register as the default pick_first balancer. + Name = "pick_first" + } + balancer.Register(pickfirstBuilder{}) +} + +// enableHealthListenerKeyType is a unique key type used in resolver attributes +// to indicate whether the health listener usage is enabled. +type enableHealthListenerKeyType struct{} + +var ( + logger = grpclog.Component("pick-first-leaf-lb") + // Name is the name of the pick_first_leaf balancer. + // It is changed to "pick_first" in init() if this balancer is to be + // registered as the default pickfirst. + Name = "pick_first_leaf" + disconnectionsMetric = expstats.RegisterInt64Count(expstats.MetricDescriptor{ + Name: "grpc.lb.pick_first.disconnections", + Description: "EXPERIMENTAL. Number of times the selected subchannel becomes disconnected.", + Unit: "disconnection", + Labels: []string{"grpc.target"}, + Default: false, + }) + connectionAttemptsSucceededMetric = expstats.RegisterInt64Count(expstats.MetricDescriptor{ + Name: "grpc.lb.pick_first.connection_attempts_succeeded", + Description: "EXPERIMENTAL. Number of successful connection attempts.", + Unit: "attempt", + Labels: []string{"grpc.target"}, + Default: false, + }) + connectionAttemptsFailedMetric = expstats.RegisterInt64Count(expstats.MetricDescriptor{ + Name: "grpc.lb.pick_first.connection_attempts_failed", + Description: "EXPERIMENTAL. Number of failed connection attempts.", + Unit: "attempt", + Labels: []string{"grpc.target"}, + Default: false, + }) +) + +const ( + // TODO: change to pick-first when this becomes the default pick_first policy. + logPrefix = "[pick-first-leaf-lb %p] " + // connectionDelayInterval is the time to wait for during the happy eyeballs + // pass before starting the next connection attempt. + connectionDelayInterval = 250 * time.Millisecond +) + +type ipAddrFamily int + +const ( + // ipAddrFamilyUnknown represents strings that can't be parsed as an IP + // address. + ipAddrFamilyUnknown ipAddrFamily = iota + ipAddrFamilyV4 + ipAddrFamilyV6 +) + +type pickfirstBuilder struct{} + +func (pickfirstBuilder) Build(cc balancer.ClientConn, bo balancer.BuildOptions) balancer.Balancer { + b := &pickfirstBalancer{ + cc: cc, + target: bo.Target.String(), + metricsRecorder: bo.MetricsRecorder, // ClientConn will always create a Metrics Recorder. + + subConns: resolver.NewAddressMap(), + state: connectivity.Connecting, + cancelConnectionTimer: func() {}, + } + b.logger = internalgrpclog.NewPrefixLogger(logger, fmt.Sprintf(logPrefix, b)) + return b +} + +func (b pickfirstBuilder) Name() string { + return Name +} + +func (pickfirstBuilder) ParseConfig(js json.RawMessage) (serviceconfig.LoadBalancingConfig, error) { + var cfg pfConfig + if err := json.Unmarshal(js, &cfg); err != nil { + return nil, fmt.Errorf("pickfirst: unable to unmarshal LB policy config: %s, error: %v", string(js), err) + } + return cfg, nil +} + +// EnableHealthListener updates the state to configure pickfirst for using a +// generic health listener. +func EnableHealthListener(state resolver.State) resolver.State { + state.Attributes = state.Attributes.WithValue(enableHealthListenerKeyType{}, true) + return state +} + +type pfConfig struct { + serviceconfig.LoadBalancingConfig `json:"-"` + + // If set to true, instructs the LB policy to shuffle the order of the list + // of endpoints received from the name resolver before attempting to + // connect to them. + ShuffleAddressList bool `json:"shuffleAddressList"` +} + +// scData keeps track of the current state of the subConn. +// It is not safe for concurrent access. +type scData struct { + // The following fields are initialized at build time and read-only after + // that. + subConn balancer.SubConn + addr resolver.Address + + rawConnectivityState connectivity.State + // The effective connectivity state based on raw connectivity, health state + // and after following sticky TransientFailure behaviour defined in A62. + effectiveState connectivity.State + lastErr error + connectionFailedInFirstPass bool +} + +func (b *pickfirstBalancer) newSCData(addr resolver.Address) (*scData, error) { + sd := &scData{ + rawConnectivityState: connectivity.Idle, + effectiveState: connectivity.Idle, + addr: addr, + } + sc, err := b.cc.NewSubConn([]resolver.Address{addr}, balancer.NewSubConnOptions{ + StateListener: func(state balancer.SubConnState) { + b.updateSubConnState(sd, state) + }, + }) + if err != nil { + return nil, err + } + sd.subConn = sc + return sd, nil +} + +type pickfirstBalancer struct { + // The following fields are initialized at build time and read-only after + // that and therefore do not need to be guarded by a mutex. + logger *internalgrpclog.PrefixLogger + cc balancer.ClientConn + target string + metricsRecorder expstats.MetricsRecorder // guaranteed to be non nil + + // The mutex is used to ensure synchronization of updates triggered + // from the idle picker and the already serialized resolver, + // SubConn state updates. + mu sync.Mutex + // State reported to the channel based on SubConn states and resolver + // updates. + state connectivity.State + // scData for active subonns mapped by address. + subConns *resolver.AddressMap + addressList addressList + firstPass bool + numTF int + cancelConnectionTimer func() + healthCheckingEnabled bool +} + +// ResolverError is called by the ClientConn when the name resolver produces +// an error or when pickfirst determined the resolver update to be invalid. +func (b *pickfirstBalancer) ResolverError(err error) { + b.mu.Lock() + defer b.mu.Unlock() + b.resolverErrorLocked(err) +} + +func (b *pickfirstBalancer) resolverErrorLocked(err error) { + if b.logger.V(2) { + b.logger.Infof("Received error from the name resolver: %v", err) + } + + // The picker will not change since the balancer does not currently + // report an error. If the balancer hasn't received a single good resolver + // update yet, transition to TRANSIENT_FAILURE. + if b.state != connectivity.TransientFailure && b.addressList.size() > 0 { + if b.logger.V(2) { + b.logger.Infof("Ignoring resolver error because balancer is using a previous good update.") + } + return + } + + b.updateBalancerState(balancer.State{ + ConnectivityState: connectivity.TransientFailure, + Picker: &picker{err: fmt.Errorf("name resolver error: %v", err)}, + }) +} + +func (b *pickfirstBalancer) UpdateClientConnState(state balancer.ClientConnState) error { + b.mu.Lock() + defer b.mu.Unlock() + b.cancelConnectionTimer() + if len(state.ResolverState.Addresses) == 0 && len(state.ResolverState.Endpoints) == 0 { + // Cleanup state pertaining to the previous resolver state. + // Treat an empty address list like an error by calling b.ResolverError. + b.closeSubConnsLocked() + b.addressList.updateAddrs(nil) + b.resolverErrorLocked(errors.New("produced zero addresses")) + return balancer.ErrBadResolverState + } + b.healthCheckingEnabled = state.ResolverState.Attributes.Value(enableHealthListenerKeyType{}) != nil + cfg, ok := state.BalancerConfig.(pfConfig) + if state.BalancerConfig != nil && !ok { + return fmt.Errorf("pickfirst: received illegal BalancerConfig (type %T): %v: %w", state.BalancerConfig, state.BalancerConfig, balancer.ErrBadResolverState) + } + + if b.logger.V(2) { + b.logger.Infof("Received new config %s, resolver state %s", pretty.ToJSON(cfg), pretty.ToJSON(state.ResolverState)) + } + + var newAddrs []resolver.Address + if endpoints := state.ResolverState.Endpoints; len(endpoints) != 0 { + // Perform the optional shuffling described in gRFC A62. The shuffling + // will change the order of endpoints but not touch the order of the + // addresses within each endpoint. - A61 + if cfg.ShuffleAddressList { + endpoints = append([]resolver.Endpoint{}, endpoints...) + internal.RandShuffle(len(endpoints), func(i, j int) { endpoints[i], endpoints[j] = endpoints[j], endpoints[i] }) + } + + // "Flatten the list by concatenating the ordered list of addresses for + // each of the endpoints, in order." - A61 + for _, endpoint := range endpoints { + newAddrs = append(newAddrs, endpoint.Addresses...) + } + } else { + // Endpoints not set, process addresses until we migrate resolver + // emissions fully to Endpoints. The top channel does wrap emitted + // addresses with endpoints, however some balancers such as weighted + // target do not forward the corresponding correct endpoints down/split + // endpoints properly. Once all balancers correctly forward endpoints + // down, can delete this else conditional. + newAddrs = state.ResolverState.Addresses + if cfg.ShuffleAddressList { + newAddrs = append([]resolver.Address{}, newAddrs...) + internal.RandShuffle(len(endpoints), func(i, j int) { endpoints[i], endpoints[j] = endpoints[j], endpoints[i] }) + } + } + + // If an address appears in multiple endpoints or in the same endpoint + // multiple times, we keep it only once. We will create only one SubConn + // for the address because an AddressMap is used to store SubConns. + // Not de-duplicating would result in attempting to connect to the same + // SubConn multiple times in the same pass. We don't want this. + newAddrs = deDupAddresses(newAddrs) + newAddrs = interleaveAddresses(newAddrs) + + prevAddr := b.addressList.currentAddress() + prevSCData, found := b.subConns.Get(prevAddr) + prevAddrsCount := b.addressList.size() + isPrevRawConnectivityStateReady := found && prevSCData.(*scData).rawConnectivityState == connectivity.Ready + b.addressList.updateAddrs(newAddrs) + + // If the previous ready SubConn exists in new address list, + // keep this connection and don't create new SubConns. + if isPrevRawConnectivityStateReady && b.addressList.seekTo(prevAddr) { + return nil + } + + b.reconcileSubConnsLocked(newAddrs) + // If it's the first resolver update or the balancer was already READY + // (but the new address list does not contain the ready SubConn) or + // CONNECTING, enter CONNECTING. + // We may be in TRANSIENT_FAILURE due to a previous empty address list, + // we should still enter CONNECTING because the sticky TF behaviour + // mentioned in A62 applies only when the TRANSIENT_FAILURE is reported + // due to connectivity failures. + if isPrevRawConnectivityStateReady || b.state == connectivity.Connecting || prevAddrsCount == 0 { + // Start connection attempt at first address. + b.forceUpdateConcludedStateLocked(balancer.State{ + ConnectivityState: connectivity.Connecting, + Picker: &picker{err: balancer.ErrNoSubConnAvailable}, + }) + b.startFirstPassLocked() + } else if b.state == connectivity.TransientFailure { + // If we're in TRANSIENT_FAILURE, we stay in TRANSIENT_FAILURE until + // we're READY. See A62. + b.startFirstPassLocked() + } + return nil +} + +// UpdateSubConnState is unused as a StateListener is always registered when +// creating SubConns. +func (b *pickfirstBalancer) UpdateSubConnState(subConn balancer.SubConn, state balancer.SubConnState) { + b.logger.Errorf("UpdateSubConnState(%v, %+v) called unexpectedly", subConn, state) +} + +func (b *pickfirstBalancer) Close() { + b.mu.Lock() + defer b.mu.Unlock() + b.closeSubConnsLocked() + b.cancelConnectionTimer() + b.state = connectivity.Shutdown +} + +// ExitIdle moves the balancer out of idle state. It can be called concurrently +// by the idlePicker and clientConn so access to variables should be +// synchronized. +func (b *pickfirstBalancer) ExitIdle() { + b.mu.Lock() + defer b.mu.Unlock() + if b.state == connectivity.Idle { + b.startFirstPassLocked() + } +} + +func (b *pickfirstBalancer) startFirstPassLocked() { + b.firstPass = true + b.numTF = 0 + // Reset the connection attempt record for existing SubConns. + for _, sd := range b.subConns.Values() { + sd.(*scData).connectionFailedInFirstPass = false + } + b.requestConnectionLocked() +} + +func (b *pickfirstBalancer) closeSubConnsLocked() { + for _, sd := range b.subConns.Values() { + sd.(*scData).subConn.Shutdown() + } + b.subConns = resolver.NewAddressMap() +} + +// deDupAddresses ensures that each address appears only once in the slice. +func deDupAddresses(addrs []resolver.Address) []resolver.Address { + seenAddrs := resolver.NewAddressMap() + retAddrs := []resolver.Address{} + + for _, addr := range addrs { + if _, ok := seenAddrs.Get(addr); ok { + continue + } + retAddrs = append(retAddrs, addr) + } + return retAddrs +} + +// interleaveAddresses interleaves addresses of both families (IPv4 and IPv6) +// as per RFC-8305 section 4. +// Whichever address family is first in the list is followed by an address of +// the other address family; that is, if the first address in the list is IPv6, +// then the first IPv4 address should be moved up in the list to be second in +// the list. It doesn't support configuring "First Address Family Count", i.e. +// there will always be a single member of the first address family at the +// beginning of the interleaved list. +// Addresses that are neither IPv4 nor IPv6 are treated as part of a third +// "unknown" family for interleaving. +// See: https://datatracker.ietf.org/doc/html/rfc8305#autoid-6 +func interleaveAddresses(addrs []resolver.Address) []resolver.Address { + familyAddrsMap := map[ipAddrFamily][]resolver.Address{} + interleavingOrder := []ipAddrFamily{} + for _, addr := range addrs { + family := addressFamily(addr.Addr) + if _, found := familyAddrsMap[family]; !found { + interleavingOrder = append(interleavingOrder, family) + } + familyAddrsMap[family] = append(familyAddrsMap[family], addr) + } + + interleavedAddrs := make([]resolver.Address, 0, len(addrs)) + + for curFamilyIdx := 0; len(interleavedAddrs) < len(addrs); curFamilyIdx = (curFamilyIdx + 1) % len(interleavingOrder) { + // Some IP types may have fewer addresses than others, so we look for + // the next type that has a remaining member to add to the interleaved + // list. + family := interleavingOrder[curFamilyIdx] + remainingMembers := familyAddrsMap[family] + if len(remainingMembers) > 0 { + interleavedAddrs = append(interleavedAddrs, remainingMembers[0]) + familyAddrsMap[family] = remainingMembers[1:] + } + } + + return interleavedAddrs +} + +// addressFamily returns the ipAddrFamily after parsing the address string. +// If the address isn't of the format "ip-address:port", it returns +// ipAddrFamilyUnknown. The address may be valid even if it's not an IP when +// using a resolver like passthrough where the address may be a hostname in +// some format that the dialer can resolve. +func addressFamily(address string) ipAddrFamily { + // Parse the IP after removing the port. + host, _, err := net.SplitHostPort(address) + if err != nil { + return ipAddrFamilyUnknown + } + ip, err := netip.ParseAddr(host) + if err != nil { + return ipAddrFamilyUnknown + } + switch { + case ip.Is4() || ip.Is4In6(): + return ipAddrFamilyV4 + case ip.Is6(): + return ipAddrFamilyV6 + default: + return ipAddrFamilyUnknown + } +} + +// reconcileSubConnsLocked updates the active subchannels based on a new address +// list from the resolver. It does this by: +// - closing subchannels: any existing subchannels associated with addresses +// that are no longer in the updated list are shut down. +// - removing subchannels: entries for these closed subchannels are removed +// from the subchannel map. +// +// This ensures that the subchannel map accurately reflects the current set of +// addresses received from the name resolver. +func (b *pickfirstBalancer) reconcileSubConnsLocked(newAddrs []resolver.Address) { + newAddrsMap := resolver.NewAddressMap() + for _, addr := range newAddrs { + newAddrsMap.Set(addr, true) + } + + for _, oldAddr := range b.subConns.Keys() { + if _, ok := newAddrsMap.Get(oldAddr); ok { + continue + } + val, _ := b.subConns.Get(oldAddr) + val.(*scData).subConn.Shutdown() + b.subConns.Delete(oldAddr) + } +} + +// shutdownRemainingLocked shuts down remaining subConns. Called when a subConn +// becomes ready, which means that all other subConn must be shutdown. +func (b *pickfirstBalancer) shutdownRemainingLocked(selected *scData) { + b.cancelConnectionTimer() + for _, v := range b.subConns.Values() { + sd := v.(*scData) + if sd.subConn != selected.subConn { + sd.subConn.Shutdown() + } + } + b.subConns = resolver.NewAddressMap() + b.subConns.Set(selected.addr, selected) +} + +// requestConnectionLocked starts connecting on the subchannel corresponding to +// the current address. If no subchannel exists, one is created. If the current +// subchannel is in TransientFailure, a connection to the next address is +// attempted until a subchannel is found. +func (b *pickfirstBalancer) requestConnectionLocked() { + if !b.addressList.isValid() { + return + } + var lastErr error + for valid := true; valid; valid = b.addressList.increment() { + curAddr := b.addressList.currentAddress() + sd, ok := b.subConns.Get(curAddr) + if !ok { + var err error + // We want to assign the new scData to sd from the outer scope, + // hence we can't use := below. + sd, err = b.newSCData(curAddr) + if err != nil { + // This should never happen, unless the clientConn is being shut + // down. + if b.logger.V(2) { + b.logger.Infof("Failed to create a subConn for address %v: %v", curAddr.String(), err) + } + // Do nothing, the LB policy will be closed soon. + return + } + b.subConns.Set(curAddr, sd) + } + + scd := sd.(*scData) + switch scd.rawConnectivityState { + case connectivity.Idle: + scd.subConn.Connect() + b.scheduleNextConnectionLocked() + return + case connectivity.TransientFailure: + // The SubConn is being re-used and failed during a previous pass + // over the addressList. It has not completed backoff yet. + // Mark it as having failed and try the next address. + scd.connectionFailedInFirstPass = true + lastErr = scd.lastErr + continue + case connectivity.Connecting: + // Wait for the connection attempt to complete or the timer to fire + // before attempting the next address. + b.scheduleNextConnectionLocked() + return + default: + b.logger.Errorf("SubConn with unexpected state %v present in SubConns map.", scd.rawConnectivityState) + return + + } + } + + // All the remaining addresses in the list are in TRANSIENT_FAILURE, end the + // first pass if possible. + b.endFirstPassIfPossibleLocked(lastErr) +} + +func (b *pickfirstBalancer) scheduleNextConnectionLocked() { + b.cancelConnectionTimer() + if !b.addressList.hasNext() { + return + } + curAddr := b.addressList.currentAddress() + cancelled := false // Access to this is protected by the balancer's mutex. + closeFn := internal.TimeAfterFunc(connectionDelayInterval, func() { + b.mu.Lock() + defer b.mu.Unlock() + // If the scheduled task is cancelled while acquiring the mutex, return. + if cancelled { + return + } + if b.logger.V(2) { + b.logger.Infof("Happy Eyeballs timer expired while waiting for connection to %q.", curAddr.Addr) + } + if b.addressList.increment() { + b.requestConnectionLocked() + } + }) + // Access to the cancellation callback held by the balancer is guarded by + // the balancer's mutex, so it's safe to set the boolean from the callback. + b.cancelConnectionTimer = sync.OnceFunc(func() { + cancelled = true + closeFn() + }) +} + +func (b *pickfirstBalancer) updateSubConnState(sd *scData, newState balancer.SubConnState) { + b.mu.Lock() + defer b.mu.Unlock() + oldState := sd.rawConnectivityState + sd.rawConnectivityState = newState.ConnectivityState + // Previously relevant SubConns can still callback with state updates. + // To prevent pickers from returning these obsolete SubConns, this logic + // is included to check if the current list of active SubConns includes this + // SubConn. + if !b.isActiveSCData(sd) { + return + } + if newState.ConnectivityState == connectivity.Shutdown { + sd.effectiveState = connectivity.Shutdown + return + } + + // Record a connection attempt when exiting CONNECTING. + if newState.ConnectivityState == connectivity.TransientFailure { + sd.connectionFailedInFirstPass = true + connectionAttemptsFailedMetric.Record(b.metricsRecorder, 1, b.target) + } + + if newState.ConnectivityState == connectivity.Ready { + connectionAttemptsSucceededMetric.Record(b.metricsRecorder, 1, b.target) + b.shutdownRemainingLocked(sd) + if !b.addressList.seekTo(sd.addr) { + // This should not fail as we should have only one SubConn after + // entering READY. The SubConn should be present in the addressList. + b.logger.Errorf("Address %q not found address list in %v", sd.addr, b.addressList.addresses) + return + } + if !b.healthCheckingEnabled { + if b.logger.V(2) { + b.logger.Infof("SubConn %p reported connectivity state READY and the health listener is disabled. Transitioning SubConn to READY.", sd.subConn) + } + + sd.effectiveState = connectivity.Ready + b.updateBalancerState(balancer.State{ + ConnectivityState: connectivity.Ready, + Picker: &picker{result: balancer.PickResult{SubConn: sd.subConn}}, + }) + return + } + if b.logger.V(2) { + b.logger.Infof("SubConn %p reported connectivity state READY. Registering health listener.", sd.subConn) + } + // Send a CONNECTING update to take the SubConn out of sticky-TF if + // required. + sd.effectiveState = connectivity.Connecting + b.updateBalancerState(balancer.State{ + ConnectivityState: connectivity.Connecting, + Picker: &picker{err: balancer.ErrNoSubConnAvailable}, + }) + sd.subConn.RegisterHealthListener(func(scs balancer.SubConnState) { + b.updateSubConnHealthState(sd, scs) + }) + return + } + + // If the LB policy is READY, and it receives a subchannel state change, + // it means that the READY subchannel has failed. + // A SubConn can also transition from CONNECTING directly to IDLE when + // a transport is successfully created, but the connection fails + // before the SubConn can send the notification for READY. We treat + // this as a successful connection and transition to IDLE. + // TODO: https://github.com/grpc/grpc-go/issues/7862 - Remove the second + // part of the if condition below once the issue is fixed. + if oldState == connectivity.Ready || (oldState == connectivity.Connecting && newState.ConnectivityState == connectivity.Idle) { + // Once a transport fails, the balancer enters IDLE and starts from + // the first address when the picker is used. + b.shutdownRemainingLocked(sd) + sd.effectiveState = newState.ConnectivityState + // READY SubConn interspliced in between CONNECTING and IDLE, need to + // account for that. + if oldState == connectivity.Connecting { + // A known issue (https://github.com/grpc/grpc-go/issues/7862) + // causes a race that prevents the READY state change notification. + // This works around it. + connectionAttemptsSucceededMetric.Record(b.metricsRecorder, 1, b.target) + } + disconnectionsMetric.Record(b.metricsRecorder, 1, b.target) + b.addressList.reset() + b.updateBalancerState(balancer.State{ + ConnectivityState: connectivity.Idle, + Picker: &idlePicker{exitIdle: sync.OnceFunc(b.ExitIdle)}, + }) + return + } + + if b.firstPass { + switch newState.ConnectivityState { + case connectivity.Connecting: + // The effective state can be in either IDLE, CONNECTING or + // TRANSIENT_FAILURE. If it's TRANSIENT_FAILURE, stay in + // TRANSIENT_FAILURE until it's READY. See A62. + if sd.effectiveState != connectivity.TransientFailure { + sd.effectiveState = connectivity.Connecting + b.updateBalancerState(balancer.State{ + ConnectivityState: connectivity.Connecting, + Picker: &picker{err: balancer.ErrNoSubConnAvailable}, + }) + } + case connectivity.TransientFailure: + sd.lastErr = newState.ConnectionError + sd.effectiveState = connectivity.TransientFailure + // Since we're re-using common SubConns while handling resolver + // updates, we could receive an out of turn TRANSIENT_FAILURE from + // a pass over the previous address list. Happy Eyeballs will also + // cause out of order updates to arrive. + + if curAddr := b.addressList.currentAddress(); equalAddressIgnoringBalAttributes(&curAddr, &sd.addr) { + b.cancelConnectionTimer() + if b.addressList.increment() { + b.requestConnectionLocked() + return + } + } + + // End the first pass if we've seen a TRANSIENT_FAILURE from all + // SubConns once. + b.endFirstPassIfPossibleLocked(newState.ConnectionError) + } + return + } + + // We have finished the first pass, keep re-connecting failing SubConns. + switch newState.ConnectivityState { + case connectivity.TransientFailure: + b.numTF = (b.numTF + 1) % b.subConns.Len() + sd.lastErr = newState.ConnectionError + if b.numTF%b.subConns.Len() == 0 { + b.updateBalancerState(balancer.State{ + ConnectivityState: connectivity.TransientFailure, + Picker: &picker{err: newState.ConnectionError}, + }) + } + // We don't need to request re-resolution since the SubConn already + // does that before reporting TRANSIENT_FAILURE. + // TODO: #7534 - Move re-resolution requests from SubConn into + // pick_first. + case connectivity.Idle: + sd.subConn.Connect() + } +} + +// endFirstPassIfPossibleLocked ends the first happy-eyeballs pass if all the +// addresses are tried and their SubConns have reported a failure. +func (b *pickfirstBalancer) endFirstPassIfPossibleLocked(lastErr error) { + // An optimization to avoid iterating over the entire SubConn map. + if b.addressList.isValid() { + return + } + // Connect() has been called on all the SubConns. The first pass can be + // ended if all the SubConns have reported a failure. + for _, v := range b.subConns.Values() { + sd := v.(*scData) + if !sd.connectionFailedInFirstPass { + return + } + } + b.firstPass = false + b.updateBalancerState(balancer.State{ + ConnectivityState: connectivity.TransientFailure, + Picker: &picker{err: lastErr}, + }) + // Start re-connecting all the SubConns that are already in IDLE. + for _, v := range b.subConns.Values() { + sd := v.(*scData) + if sd.rawConnectivityState == connectivity.Idle { + sd.subConn.Connect() + } + } +} + +func (b *pickfirstBalancer) isActiveSCData(sd *scData) bool { + activeSD, found := b.subConns.Get(sd.addr) + return found && activeSD == sd +} + +func (b *pickfirstBalancer) updateSubConnHealthState(sd *scData, state balancer.SubConnState) { + b.mu.Lock() + defer b.mu.Unlock() + // Previously relevant SubConns can still callback with state updates. + // To prevent pickers from returning these obsolete SubConns, this logic + // is included to check if the current list of active SubConns includes + // this SubConn. + if !b.isActiveSCData(sd) { + return + } + sd.effectiveState = state.ConnectivityState + switch state.ConnectivityState { + case connectivity.Ready: + b.updateBalancerState(balancer.State{ + ConnectivityState: connectivity.Ready, + Picker: &picker{result: balancer.PickResult{SubConn: sd.subConn}}, + }) + case connectivity.TransientFailure: + b.updateBalancerState(balancer.State{ + ConnectivityState: connectivity.TransientFailure, + Picker: &picker{err: fmt.Errorf("pickfirst: health check failure: %v", state.ConnectionError)}, + }) + case connectivity.Connecting: + b.updateBalancerState(balancer.State{ + ConnectivityState: connectivity.Connecting, + Picker: &picker{err: balancer.ErrNoSubConnAvailable}, + }) + default: + b.logger.Errorf("Got unexpected health update for SubConn %p: %v", state) + } +} + +// updateBalancerState stores the state reported to the channel and calls +// ClientConn.UpdateState(). As an optimization, it avoids sending duplicate +// updates to the channel. +func (b *pickfirstBalancer) updateBalancerState(newState balancer.State) { + // In case of TransientFailures allow the picker to be updated to update + // the connectivity error, in all other cases don't send duplicate state + // updates. + if newState.ConnectivityState == b.state && b.state != connectivity.TransientFailure { + return + } + b.forceUpdateConcludedStateLocked(newState) +} + +// forceUpdateConcludedStateLocked stores the state reported to the channel and +// calls ClientConn.UpdateState(). +// A separate function is defined to force update the ClientConn state since the +// channel doesn't correctly assume that LB policies start in CONNECTING and +// relies on LB policy to send an initial CONNECTING update. +func (b *pickfirstBalancer) forceUpdateConcludedStateLocked(newState balancer.State) { + b.state = newState.ConnectivityState + b.cc.UpdateState(newState) +} + +type picker struct { + result balancer.PickResult + err error +} + +func (p *picker) Pick(balancer.PickInfo) (balancer.PickResult, error) { + return p.result, p.err +} + +// idlePicker is used when the SubConn is IDLE and kicks the SubConn into +// CONNECTING when Pick is called. +type idlePicker struct { + exitIdle func() +} + +func (i *idlePicker) Pick(balancer.PickInfo) (balancer.PickResult, error) { + i.exitIdle() + return balancer.PickResult{}, balancer.ErrNoSubConnAvailable +} + +// addressList manages sequentially iterating over addresses present in a list +// of endpoints. It provides a 1 dimensional view of the addresses present in +// the endpoints. +// This type is not safe for concurrent access. +type addressList struct { + addresses []resolver.Address + idx int +} + +func (al *addressList) isValid() bool { + return al.idx < len(al.addresses) +} + +func (al *addressList) size() int { + return len(al.addresses) +} + +// increment moves to the next index in the address list. +// This method returns false if it went off the list, true otherwise. +func (al *addressList) increment() bool { + if !al.isValid() { + return false + } + al.idx++ + return al.idx < len(al.addresses) +} + +// currentAddress returns the current address pointed to in the addressList. +// If the list is in an invalid state, it returns an empty address instead. +func (al *addressList) currentAddress() resolver.Address { + if !al.isValid() { + return resolver.Address{} + } + return al.addresses[al.idx] +} + +func (al *addressList) reset() { + al.idx = 0 +} + +func (al *addressList) updateAddrs(addrs []resolver.Address) { + al.addresses = addrs + al.reset() +} + +// seekTo returns false if the needle was not found and the current index was +// left unchanged. +func (al *addressList) seekTo(needle resolver.Address) bool { + for ai, addr := range al.addresses { + if !equalAddressIgnoringBalAttributes(&addr, &needle) { + continue + } + al.idx = ai + return true + } + return false +} + +// hasNext returns whether incrementing the addressList will result in moving +// past the end of the list. If the list has already moved past the end, it +// returns false. +func (al *addressList) hasNext() bool { + if !al.isValid() { + return false + } + return al.idx+1 < len(al.addresses) +} + +// equalAddressIgnoringBalAttributes returns true is a and b are considered +// equal. This is different from the Equal method on the resolver.Address type +// which considers all fields to determine equality. Here, we only consider +// fields that are meaningful to the SubConn. +func equalAddressIgnoringBalAttributes(a, b *resolver.Address) bool { + return a.Addr == b.Addr && a.ServerName == b.ServerName && + a.Attributes.Equal(b.Attributes) && + a.Metadata == b.Metadata +} |