332 lines
8.3 KiB
Go
332 lines
8.3 KiB
Go
/*
|
|
*
|
|
* Copyright 2017 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 (
|
|
"io"
|
|
"sync"
|
|
"sync/atomic"
|
|
|
|
"golang.org/x/net/context"
|
|
"google.golang.org/grpc/balancer"
|
|
"google.golang.org/grpc/channelz"
|
|
"google.golang.org/grpc/codes"
|
|
"google.golang.org/grpc/grpclog"
|
|
"google.golang.org/grpc/metadata"
|
|
"google.golang.org/grpc/resolver"
|
|
"google.golang.org/grpc/status"
|
|
"google.golang.org/grpc/transport"
|
|
)
|
|
|
|
// pickerWrapper is a wrapper of balancer.Picker. It blocks on certain pick
|
|
// actions and unblock when there's a picker update.
|
|
type pickerWrapper struct {
|
|
mu sync.Mutex
|
|
done bool
|
|
blockingCh chan struct{}
|
|
picker balancer.Picker
|
|
|
|
// The latest connection happened.
|
|
connErrMu sync.Mutex
|
|
connErr error
|
|
|
|
stickinessMDKey atomic.Value
|
|
stickiness *stickyStore
|
|
}
|
|
|
|
func newPickerWrapper() *pickerWrapper {
|
|
bp := &pickerWrapper{
|
|
blockingCh: make(chan struct{}),
|
|
stickiness: newStickyStore(),
|
|
}
|
|
return bp
|
|
}
|
|
|
|
func (bp *pickerWrapper) updateConnectionError(err error) {
|
|
bp.connErrMu.Lock()
|
|
bp.connErr = err
|
|
bp.connErrMu.Unlock()
|
|
}
|
|
|
|
func (bp *pickerWrapper) connectionError() error {
|
|
bp.connErrMu.Lock()
|
|
err := bp.connErr
|
|
bp.connErrMu.Unlock()
|
|
return err
|
|
}
|
|
|
|
func (bp *pickerWrapper) updateStickinessMDKey(newKey string) {
|
|
// No need to check ok because mdKey == "" if ok == false.
|
|
if oldKey, _ := bp.stickinessMDKey.Load().(string); oldKey != newKey {
|
|
bp.stickinessMDKey.Store(newKey)
|
|
bp.stickiness.reset(newKey)
|
|
}
|
|
}
|
|
|
|
func (bp *pickerWrapper) getStickinessMDKey() string {
|
|
// No need to check ok because mdKey == "" if ok == false.
|
|
mdKey, _ := bp.stickinessMDKey.Load().(string)
|
|
return mdKey
|
|
}
|
|
|
|
func (bp *pickerWrapper) clearStickinessState() {
|
|
if oldKey := bp.getStickinessMDKey(); oldKey != "" {
|
|
// There's no need to reset store if mdKey was "".
|
|
bp.stickiness.reset(oldKey)
|
|
}
|
|
}
|
|
|
|
// updatePicker is called by UpdateBalancerState. It unblocks all blocked pick.
|
|
func (bp *pickerWrapper) updatePicker(p balancer.Picker) {
|
|
bp.mu.Lock()
|
|
if bp.done {
|
|
bp.mu.Unlock()
|
|
return
|
|
}
|
|
bp.picker = p
|
|
// bp.blockingCh should never be nil.
|
|
close(bp.blockingCh)
|
|
bp.blockingCh = make(chan struct{})
|
|
bp.mu.Unlock()
|
|
}
|
|
|
|
func doneChannelzWrapper(acw *acBalancerWrapper, done func(balancer.DoneInfo)) func(balancer.DoneInfo) {
|
|
acw.mu.Lock()
|
|
ac := acw.ac
|
|
acw.mu.Unlock()
|
|
ac.incrCallsStarted()
|
|
return func(b balancer.DoneInfo) {
|
|
if b.Err != nil && b.Err != io.EOF {
|
|
ac.incrCallsFailed()
|
|
} else {
|
|
ac.incrCallsSucceeded()
|
|
}
|
|
if done != nil {
|
|
done(b)
|
|
}
|
|
}
|
|
}
|
|
|
|
// pick returns the transport that will be used for the RPC.
|
|
// It may block in the following cases:
|
|
// - there's no picker
|
|
// - the current picker returns ErrNoSubConnAvailable
|
|
// - the current picker returns other errors and failfast is false.
|
|
// - the subConn returned by the current picker is not READY
|
|
// When one of these situations happens, pick blocks until the picker gets updated.
|
|
func (bp *pickerWrapper) pick(ctx context.Context, failfast bool, opts balancer.PickOptions) (transport.ClientTransport, func(balancer.DoneInfo), error) {
|
|
|
|
mdKey := bp.getStickinessMDKey()
|
|
stickyKey, isSticky := stickyKeyFromContext(ctx, mdKey)
|
|
|
|
// Potential race here: if stickinessMDKey is updated after the above two
|
|
// lines, and this pick is a sticky pick, the following put could add an
|
|
// entry to sticky store with an outdated sticky key.
|
|
//
|
|
// The solution: keep the current md key in sticky store, and at the
|
|
// beginning of each get/put, check the mdkey against store.curMDKey.
|
|
// - Cons: one more string comparing for each get/put.
|
|
// - Pros: the string matching happens inside get/put, so the overhead for
|
|
// non-sticky RPCs will be minimal.
|
|
|
|
if isSticky {
|
|
if t, ok := bp.stickiness.get(mdKey, stickyKey); ok {
|
|
// Done function returned is always nil.
|
|
return t, nil, nil
|
|
}
|
|
}
|
|
|
|
var (
|
|
p balancer.Picker
|
|
ch chan struct{}
|
|
)
|
|
|
|
for {
|
|
bp.mu.Lock()
|
|
if bp.done {
|
|
bp.mu.Unlock()
|
|
return nil, nil, ErrClientConnClosing
|
|
}
|
|
|
|
if bp.picker == nil {
|
|
ch = bp.blockingCh
|
|
}
|
|
if ch == bp.blockingCh {
|
|
// This could happen when either:
|
|
// - bp.picker is nil (the previous if condition), or
|
|
// - has called pick on the current picker.
|
|
bp.mu.Unlock()
|
|
select {
|
|
case <-ctx.Done():
|
|
return nil, nil, ctx.Err()
|
|
case <-ch:
|
|
}
|
|
continue
|
|
}
|
|
|
|
ch = bp.blockingCh
|
|
p = bp.picker
|
|
bp.mu.Unlock()
|
|
|
|
subConn, done, err := p.Pick(ctx, opts)
|
|
|
|
if err != nil {
|
|
switch err {
|
|
case balancer.ErrNoSubConnAvailable:
|
|
continue
|
|
case balancer.ErrTransientFailure:
|
|
if !failfast {
|
|
continue
|
|
}
|
|
return nil, nil, status.Errorf(codes.Unavailable, "%v, latest connection error: %v", err, bp.connectionError())
|
|
default:
|
|
// err is some other error.
|
|
return nil, nil, toRPCErr(err)
|
|
}
|
|
}
|
|
|
|
acw, ok := subConn.(*acBalancerWrapper)
|
|
if !ok {
|
|
grpclog.Infof("subconn returned from pick is not *acBalancerWrapper")
|
|
continue
|
|
}
|
|
if t, ok := acw.getAddrConn().getReadyTransport(); ok {
|
|
if isSticky {
|
|
bp.stickiness.put(mdKey, stickyKey, acw)
|
|
}
|
|
if channelz.IsOn() {
|
|
return t, doneChannelzWrapper(acw, done), nil
|
|
}
|
|
return t, done, nil
|
|
}
|
|
grpclog.Infof("blockingPicker: the picked transport is not ready, loop back to repick")
|
|
// If ok == false, ac.state is not READY.
|
|
// A valid picker always returns READY subConn. This means the state of ac
|
|
// just changed, and picker will be updated shortly.
|
|
// continue back to the beginning of the for loop to repick.
|
|
}
|
|
}
|
|
|
|
func (bp *pickerWrapper) close() {
|
|
bp.mu.Lock()
|
|
defer bp.mu.Unlock()
|
|
if bp.done {
|
|
return
|
|
}
|
|
bp.done = true
|
|
close(bp.blockingCh)
|
|
}
|
|
|
|
type stickyStoreEntry struct {
|
|
acw *acBalancerWrapper
|
|
addr resolver.Address
|
|
}
|
|
|
|
type stickyStore struct {
|
|
mu sync.Mutex
|
|
// curMDKey is check before every get/put to avoid races. The operation will
|
|
// abort immediately when the given mdKey is different from the curMDKey.
|
|
curMDKey string
|
|
store map[string]*stickyStoreEntry
|
|
}
|
|
|
|
func newStickyStore() *stickyStore {
|
|
return &stickyStore{
|
|
store: make(map[string]*stickyStoreEntry),
|
|
}
|
|
}
|
|
|
|
// reset clears the map in stickyStore, and set the currentMDKey to newMDKey.
|
|
func (ss *stickyStore) reset(newMDKey string) {
|
|
ss.mu.Lock()
|
|
ss.curMDKey = newMDKey
|
|
ss.store = make(map[string]*stickyStoreEntry)
|
|
ss.mu.Unlock()
|
|
}
|
|
|
|
// stickyKey is the key to look up in store. mdKey will be checked against
|
|
// curMDKey to avoid races.
|
|
func (ss *stickyStore) put(mdKey, stickyKey string, acw *acBalancerWrapper) {
|
|
ss.mu.Lock()
|
|
defer ss.mu.Unlock()
|
|
if mdKey != ss.curMDKey {
|
|
return
|
|
}
|
|
// TODO(stickiness): limit the total number of entries.
|
|
ss.store[stickyKey] = &stickyStoreEntry{
|
|
acw: acw,
|
|
addr: acw.getAddrConn().getCurAddr(),
|
|
}
|
|
}
|
|
|
|
// stickyKey is the key to look up in store. mdKey will be checked against
|
|
// curMDKey to avoid races.
|
|
func (ss *stickyStore) get(mdKey, stickyKey string) (transport.ClientTransport, bool) {
|
|
ss.mu.Lock()
|
|
defer ss.mu.Unlock()
|
|
if mdKey != ss.curMDKey {
|
|
return nil, false
|
|
}
|
|
entry, ok := ss.store[stickyKey]
|
|
if !ok {
|
|
return nil, false
|
|
}
|
|
ac := entry.acw.getAddrConn()
|
|
if ac.getCurAddr() != entry.addr {
|
|
delete(ss.store, stickyKey)
|
|
return nil, false
|
|
}
|
|
t, ok := ac.getReadyTransport()
|
|
if !ok {
|
|
delete(ss.store, stickyKey)
|
|
return nil, false
|
|
}
|
|
return t, true
|
|
}
|
|
|
|
// Get one value from metadata in ctx with key stickinessMDKey.
|
|
//
|
|
// It returns "", false if stickinessMDKey is an empty string.
|
|
func stickyKeyFromContext(ctx context.Context, stickinessMDKey string) (string, bool) {
|
|
if stickinessMDKey == "" {
|
|
return "", false
|
|
}
|
|
|
|
md, added, ok := metadata.FromOutgoingContextRaw(ctx)
|
|
if !ok {
|
|
return "", false
|
|
}
|
|
|
|
if vv, ok := md[stickinessMDKey]; ok {
|
|
if len(vv) > 0 {
|
|
return vv[0], true
|
|
}
|
|
}
|
|
|
|
for _, ss := range added {
|
|
for i := 0; i < len(ss)-1; i += 2 {
|
|
if ss[i] == stickinessMDKey {
|
|
return ss[i+1], true
|
|
}
|
|
}
|
|
}
|
|
|
|
return "", false
|
|
}
|