VOL-1497 : Add more control to kv/memory access
- Added kv locking mechanism (etcd only)
- (watch) control path access whenever possible
- (watch) use a transaction for updates and merge with memory
- cleaned up vendoring
- misc changes to fix exceptions found along the way
Amendments:
- Copyright header got removed in auto-generated file
- Changed default locking to false for KV list operation
- Updated backend api to allow the passing of locking parameter
Change-Id: Ie1a55d3ca8b9d92ae71a85ce42bb22fcf1419e2c
diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/balancer.go b/vendor/go.etcd.io/etcd/clientv3/balancer/balancer.go
new file mode 100644
index 0000000..25dc2b7
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/clientv3/balancer/balancer.go
@@ -0,0 +1,275 @@
+// Copyright 2018 The etcd 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 balancer
+
+import (
+ "fmt"
+ "strconv"
+ "sync"
+ "time"
+
+ "go.etcd.io/etcd/clientv3/balancer/picker"
+
+ "go.uber.org/zap"
+ "google.golang.org/grpc/balancer"
+ "google.golang.org/grpc/connectivity"
+ "google.golang.org/grpc/resolver"
+ _ "google.golang.org/grpc/resolver/dns" // register DNS resolver
+ _ "google.golang.org/grpc/resolver/passthrough" // register passthrough resolver
+)
+
+// RegisterBuilder creates and registers a builder. Since this function calls balancer.Register, it
+// must be invoked at initialization time.
+func RegisterBuilder(cfg Config) {
+ bb := &builder{cfg}
+ balancer.Register(bb)
+
+ bb.cfg.Logger.Info(
+ "registered balancer",
+ zap.String("policy", bb.cfg.Policy.String()),
+ zap.String("name", bb.cfg.Name),
+ )
+}
+
+type builder struct {
+ cfg Config
+}
+
+// Build is called initially when creating "ccBalancerWrapper".
+// "grpc.Dial" is called to this client connection.
+// Then, resolved addresses will be handled via "HandleResolvedAddrs".
+func (b *builder) Build(cc balancer.ClientConn, opt balancer.BuildOptions) balancer.Balancer {
+ bb := &baseBalancer{
+ id: strconv.FormatInt(time.Now().UnixNano(), 36),
+ policy: b.cfg.Policy,
+ name: b.cfg.Policy.String(),
+ lg: b.cfg.Logger,
+
+ addrToSc: make(map[resolver.Address]balancer.SubConn),
+ scToAddr: make(map[balancer.SubConn]resolver.Address),
+ scToSt: make(map[balancer.SubConn]connectivity.State),
+
+ currentConn: nil,
+ csEvltr: &connectivityStateEvaluator{},
+
+ // initialize picker always returns "ErrNoSubConnAvailable"
+ Picker: picker.NewErr(balancer.ErrNoSubConnAvailable),
+ }
+ if b.cfg.Name != "" {
+ bb.name = b.cfg.Name
+ }
+ if bb.lg == nil {
+ bb.lg = zap.NewNop()
+ }
+
+ // TODO: support multiple connections
+ bb.mu.Lock()
+ bb.currentConn = cc
+ bb.mu.Unlock()
+
+ bb.lg.Info(
+ "built balancer",
+ zap.String("balancer-id", bb.id),
+ zap.String("policy", bb.policy.String()),
+ zap.String("resolver-target", cc.Target()),
+ )
+ return bb
+}
+
+// Name implements "grpc/balancer.Builder" interface.
+func (b *builder) Name() string { return b.cfg.Name }
+
+// Balancer defines client balancer interface.
+type Balancer interface {
+ // Balancer is called on specified client connection. Client initiates gRPC
+ // connection with "grpc.Dial(addr, grpc.WithBalancerName)", and then those resolved
+ // addresses are passed to "grpc/balancer.Balancer.HandleResolvedAddrs".
+ // For each resolved address, balancer calls "balancer.ClientConn.NewSubConn".
+ // "grpc/balancer.Balancer.HandleSubConnStateChange" is called when connectivity state
+ // changes, thus requires failover logic in this method.
+ balancer.Balancer
+
+ // Picker calls "Pick" for every client request.
+ picker.Picker
+}
+
+type baseBalancer struct {
+ id string
+ policy picker.Policy
+ name string
+ lg *zap.Logger
+
+ mu sync.RWMutex
+
+ addrToSc map[resolver.Address]balancer.SubConn
+ scToAddr map[balancer.SubConn]resolver.Address
+ scToSt map[balancer.SubConn]connectivity.State
+
+ currentConn balancer.ClientConn
+ currentState connectivity.State
+ csEvltr *connectivityStateEvaluator
+
+ picker.Picker
+}
+
+// HandleResolvedAddrs implements "grpc/balancer.Balancer" interface.
+// gRPC sends initial or updated resolved addresses from "Build".
+func (bb *baseBalancer) HandleResolvedAddrs(addrs []resolver.Address, err error) {
+ if err != nil {
+ bb.lg.Warn("HandleResolvedAddrs called with error", zap.String("balancer-id", bb.id), zap.Error(err))
+ return
+ }
+ bb.lg.Info("resolved", zap.String("balancer-id", bb.id), zap.Strings("addresses", addrsToStrings(addrs)))
+
+ bb.mu.Lock()
+ defer bb.mu.Unlock()
+
+ resolved := make(map[resolver.Address]struct{})
+ for _, addr := range addrs {
+ resolved[addr] = struct{}{}
+ if _, ok := bb.addrToSc[addr]; !ok {
+ sc, err := bb.currentConn.NewSubConn([]resolver.Address{addr}, balancer.NewSubConnOptions{})
+ if err != nil {
+ bb.lg.Warn("NewSubConn failed", zap.String("balancer-id", bb.id), zap.Error(err), zap.String("address", addr.Addr))
+ continue
+ }
+ bb.addrToSc[addr] = sc
+ bb.scToAddr[sc] = addr
+ bb.scToSt[sc] = connectivity.Idle
+ sc.Connect()
+ }
+ }
+
+ for addr, sc := range bb.addrToSc {
+ if _, ok := resolved[addr]; !ok {
+ // was removed by resolver or failed to create subconn
+ bb.currentConn.RemoveSubConn(sc)
+ delete(bb.addrToSc, addr)
+
+ bb.lg.Info(
+ "removed subconn",
+ zap.String("balancer-id", bb.id),
+ zap.String("address", addr.Addr),
+ zap.String("subconn", scToString(sc)),
+ )
+
+ // Keep the state of this sc in bb.scToSt until sc's state becomes Shutdown.
+ // The entry will be deleted in HandleSubConnStateChange.
+ // (DO NOT) delete(bb.scToAddr, sc)
+ // (DO NOT) delete(bb.scToSt, sc)
+ }
+ }
+}
+
+// HandleSubConnStateChange implements "grpc/balancer.Balancer" interface.
+func (bb *baseBalancer) HandleSubConnStateChange(sc balancer.SubConn, s connectivity.State) {
+ bb.mu.Lock()
+ defer bb.mu.Unlock()
+
+ old, ok := bb.scToSt[sc]
+ if !ok {
+ bb.lg.Warn(
+ "state change for an unknown subconn",
+ zap.String("balancer-id", bb.id),
+ zap.String("subconn", scToString(sc)),
+ zap.String("state", s.String()),
+ )
+ return
+ }
+
+ bb.lg.Info(
+ "state changed",
+ zap.String("balancer-id", bb.id),
+ zap.Bool("connected", s == connectivity.Ready),
+ zap.String("subconn", scToString(sc)),
+ zap.String("address", bb.scToAddr[sc].Addr),
+ zap.String("old-state", old.String()),
+ zap.String("new-state", s.String()),
+ )
+
+ bb.scToSt[sc] = s
+ switch s {
+ case connectivity.Idle:
+ sc.Connect()
+ case connectivity.Shutdown:
+ // When an address was removed by resolver, b called RemoveSubConn but
+ // kept the sc's state in scToSt. Remove state for this sc here.
+ delete(bb.scToAddr, sc)
+ delete(bb.scToSt, sc)
+ }
+
+ oldAggrState := bb.currentState
+ bb.currentState = bb.csEvltr.recordTransition(old, s)
+
+ // Regenerate picker when one of the following happens:
+ // - this sc became ready from not-ready
+ // - this sc became not-ready from ready
+ // - the aggregated state of balancer became TransientFailure from non-TransientFailure
+ // - the aggregated state of balancer became non-TransientFailure from TransientFailure
+ if (s == connectivity.Ready) != (old == connectivity.Ready) ||
+ (bb.currentState == connectivity.TransientFailure) != (oldAggrState == connectivity.TransientFailure) {
+ bb.regeneratePicker()
+ }
+
+ bb.currentConn.UpdateBalancerState(bb.currentState, bb.Picker)
+ return
+}
+
+func (bb *baseBalancer) regeneratePicker() {
+ if bb.currentState == connectivity.TransientFailure {
+ bb.lg.Info(
+ "generated transient error picker",
+ zap.String("balancer-id", bb.id),
+ zap.String("policy", bb.policy.String()),
+ )
+ bb.Picker = picker.NewErr(balancer.ErrTransientFailure)
+ return
+ }
+
+ // only pass ready subconns to picker
+ scs := make([]balancer.SubConn, 0)
+ addrToSc := make(map[resolver.Address]balancer.SubConn)
+ scToAddr := make(map[balancer.SubConn]resolver.Address)
+ for addr, sc := range bb.addrToSc {
+ if st, ok := bb.scToSt[sc]; ok && st == connectivity.Ready {
+ scs = append(scs, sc)
+ addrToSc[addr] = sc
+ scToAddr[sc] = addr
+ }
+ }
+
+ switch bb.policy {
+ case picker.RoundrobinBalanced:
+ bb.Picker = picker.NewRoundrobinBalanced(bb.lg, scs, addrToSc, scToAddr)
+
+ default:
+ panic(fmt.Errorf("invalid balancer picker policy (%d)", bb.policy))
+ }
+
+ bb.lg.Info(
+ "generated picker",
+ zap.String("balancer-id", bb.id),
+ zap.String("policy", bb.policy.String()),
+ zap.Strings("subconn-ready", scsToStrings(addrToSc)),
+ zap.Int("subconn-size", len(addrToSc)),
+ )
+}
+
+// Close implements "grpc/balancer.Balancer" interface.
+// Close is a nop because base balancer doesn't have internal state to clean up,
+// and it doesn't need to call RemoveSubConn for the SubConns.
+func (bb *baseBalancer) Close() {
+ // TODO
+}