diff options
Diffstat (limited to 'vendor/google.golang.org/grpc/grpclb_util.go')
| -rw-r--r-- | vendor/google.golang.org/grpc/grpclb_util.go | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/vendor/google.golang.org/grpc/grpclb_util.go b/vendor/google.golang.org/grpc/grpclb_util.go new file mode 100644 index 000000000..063ba9d85 --- /dev/null +++ b/vendor/google.golang.org/grpc/grpclb_util.go @@ -0,0 +1,214 @@ +/* + * + * Copyright 2016 gRPC authors. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + */ + +package grpc + +import ( + "fmt" + "sync" + "time" + + "google.golang.org/grpc/balancer" + "google.golang.org/grpc/connectivity" + "google.golang.org/grpc/resolver" +) + +// The parent ClientConn should re-resolve when grpclb loses connection to the +// remote balancer. When the ClientConn inside grpclb gets a TransientFailure, +// it calls lbManualResolver.ResolveNow(), which calls parent ClientConn's +// ResolveNow, and eventually results in re-resolve happening in parent +// ClientConn's resolver (DNS for example). +// +// parent +// ClientConn +// +-----------------------------------------------------------------+ +// | parent +---------------------------------+ | +// | DNS ClientConn | grpclb | | +// | resolver balancerWrapper | | | +// | + + | grpclb grpclb | | +// | | | | ManualResolver ClientConn | | +// | | | | + + | | +// | | | | | | Transient | | +// | | | | | | Failure | | +// | | | | | <--------- | | | +// | | | <--------------- | ResolveNow | | | +// | | <--------- | ResolveNow | | | | | +// | | ResolveNow | | | | | | +// | | | | | | | | +// | + + | + + | | +// | +---------------------------------+ | +// +-----------------------------------------------------------------+ + +// lbManualResolver is used by the ClientConn inside grpclb. It's a manual +// resolver with a special ResolveNow() function. +// +// When ResolveNow() is called, it calls ResolveNow() on the parent ClientConn, +// so when grpclb client lose contact with remote balancers, the parent +// ClientConn's resolver will re-resolve. +type lbManualResolver struct { + scheme string + ccr resolver.ClientConn + + ccb balancer.ClientConn +} + +func (r *lbManualResolver) Build(_ resolver.Target, cc resolver.ClientConn, _ resolver.BuildOption) (resolver.Resolver, error) { + r.ccr = cc + return r, nil +} + +func (r *lbManualResolver) Scheme() string { + return r.scheme +} + +// ResolveNow calls resolveNow on the parent ClientConn. +func (r *lbManualResolver) ResolveNow(o resolver.ResolveNowOption) { + r.ccb.ResolveNow(o) +} + +// Close is a noop for Resolver. +func (*lbManualResolver) Close() {} + +// NewAddress calls cc.NewAddress. +func (r *lbManualResolver) NewAddress(addrs []resolver.Address) { + r.ccr.NewAddress(addrs) +} + +// NewServiceConfig calls cc.NewServiceConfig. +func (r *lbManualResolver) NewServiceConfig(sc string) { + r.ccr.NewServiceConfig(sc) +} + +const subConnCacheTime = time.Second * 10 + +// lbCacheClientConn is a wrapper balancer.ClientConn with a SubConn cache. +// SubConns will be kept in cache for subConnCacheTime before being removed. +// +// Its new and remove methods are updated to do cache first. +type lbCacheClientConn struct { + cc balancer.ClientConn + timeout time.Duration + + mu sync.Mutex + // subConnCache only keeps subConns that are being deleted. + subConnCache map[resolver.Address]*subConnCacheEntry + subConnToAddr map[balancer.SubConn]resolver.Address +} + +type subConnCacheEntry struct { + sc balancer.SubConn + + cancel func() + abortDeleting bool +} + +func newLBCacheClientConn(cc balancer.ClientConn) *lbCacheClientConn { + return &lbCacheClientConn{ + cc: cc, + timeout: subConnCacheTime, + subConnCache: make(map[resolver.Address]*subConnCacheEntry), + subConnToAddr: make(map[balancer.SubConn]resolver.Address), + } +} + +func (ccc *lbCacheClientConn) NewSubConn(addrs []resolver.Address, opts balancer.NewSubConnOptions) (balancer.SubConn, error) { + if len(addrs) != 1 { + return nil, fmt.Errorf("grpclb calling NewSubConn with addrs of length %v", len(addrs)) + } + addrWithoutMD := addrs[0] + addrWithoutMD.Metadata = nil + + ccc.mu.Lock() + defer ccc.mu.Unlock() + if entry, ok := ccc.subConnCache[addrWithoutMD]; ok { + // If entry is in subConnCache, the SubConn was being deleted. + // cancel function will never be nil. + entry.cancel() + delete(ccc.subConnCache, addrWithoutMD) + return entry.sc, nil + } + + scNew, err := ccc.cc.NewSubConn(addrs, opts) + if err != nil { + return nil, err + } + + ccc.subConnToAddr[scNew] = addrWithoutMD + return scNew, nil +} + +func (ccc *lbCacheClientConn) RemoveSubConn(sc balancer.SubConn) { + ccc.mu.Lock() + defer ccc.mu.Unlock() + addr, ok := ccc.subConnToAddr[sc] + if !ok { + return + } + + if entry, ok := ccc.subConnCache[addr]; ok { + if entry.sc != sc { + // This could happen if NewSubConn was called multiple times for the + // same address, and those SubConns are all removed. We remove sc + // immediately here. + delete(ccc.subConnToAddr, sc) + ccc.cc.RemoveSubConn(sc) + } + return + } + + entry := &subConnCacheEntry{ + sc: sc, + } + ccc.subConnCache[addr] = entry + + timer := time.AfterFunc(ccc.timeout, func() { + ccc.mu.Lock() + if entry.abortDeleting { + return + } + ccc.cc.RemoveSubConn(sc) + delete(ccc.subConnToAddr, sc) + delete(ccc.subConnCache, addr) + ccc.mu.Unlock() + }) + entry.cancel = func() { + if !timer.Stop() { + // If stop was not successful, the timer has fired (this can only + // happen in a race). But the deleting function is blocked on ccc.mu + // because the mutex was held by the caller of this function. + // + // Set abortDeleting to true to abort the deleting function. When + // the lock is released, the deleting function will acquire the + // lock, check the value of abortDeleting and return. + entry.abortDeleting = true + } + } +} + +func (ccc *lbCacheClientConn) UpdateBalancerState(s connectivity.State, p balancer.Picker) { + ccc.cc.UpdateBalancerState(s, p) +} + +func (ccc *lbCacheClientConn) close() { + ccc.mu.Lock() + // Only cancel all existing timers. There's no need to remove SubConns. + for _, entry := range ccc.subConnCache { + entry.cancel() + } + ccc.mu.Unlock() +} |