mirror of
https://github.com/restic/restic.git
synced 2024-08-23 12:50:45 +02:00
190 lines
4.9 KiB
Go
190 lines
4.9 KiB
Go
/*
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*
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* Copyright 2017 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package grpc
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import (
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"context"
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"io"
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"sync"
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"google.golang.org/grpc/balancer"
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"google.golang.org/grpc/codes"
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"google.golang.org/grpc/grpclog"
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"google.golang.org/grpc/internal/channelz"
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"google.golang.org/grpc/internal/transport"
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"google.golang.org/grpc/status"
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)
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// pickerWrapper is a wrapper of balancer.Picker. It blocks on certain pick
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// actions and unblock when there's a picker update.
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type pickerWrapper struct {
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mu sync.Mutex
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done bool
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blockingCh chan struct{}
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picker balancer.Picker
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// The latest connection happened.
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connErrMu sync.Mutex
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connErr error
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}
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func newPickerWrapper() *pickerWrapper {
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bp := &pickerWrapper{blockingCh: make(chan struct{})}
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return bp
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}
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func (bp *pickerWrapper) updateConnectionError(err error) {
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bp.connErrMu.Lock()
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bp.connErr = err
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bp.connErrMu.Unlock()
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}
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func (bp *pickerWrapper) connectionError() error {
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bp.connErrMu.Lock()
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err := bp.connErr
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bp.connErrMu.Unlock()
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return err
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}
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// updatePicker is called by UpdateBalancerState. It unblocks all blocked pick.
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func (bp *pickerWrapper) updatePicker(p balancer.Picker) {
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bp.mu.Lock()
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if bp.done {
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bp.mu.Unlock()
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return
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}
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bp.picker = p
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// bp.blockingCh should never be nil.
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close(bp.blockingCh)
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bp.blockingCh = make(chan struct{})
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bp.mu.Unlock()
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}
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func doneChannelzWrapper(acw *acBalancerWrapper, done func(balancer.DoneInfo)) func(balancer.DoneInfo) {
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acw.mu.Lock()
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ac := acw.ac
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acw.mu.Unlock()
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ac.incrCallsStarted()
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return func(b balancer.DoneInfo) {
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if b.Err != nil && b.Err != io.EOF {
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ac.incrCallsFailed()
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} else {
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ac.incrCallsSucceeded()
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}
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if done != nil {
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done(b)
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}
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}
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}
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// pick returns the transport that will be used for the RPC.
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// It may block in the following cases:
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// - there's no picker
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// - the current picker returns ErrNoSubConnAvailable
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// - the current picker returns other errors and failfast is false.
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// - the subConn returned by the current picker is not READY
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// When one of these situations happens, pick blocks until the picker gets updated.
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func (bp *pickerWrapper) pick(ctx context.Context, failfast bool, opts balancer.PickOptions) (transport.ClientTransport, func(balancer.DoneInfo), error) {
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var ch chan struct{}
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for {
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bp.mu.Lock()
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if bp.done {
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bp.mu.Unlock()
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return nil, nil, ErrClientConnClosing
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}
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if bp.picker == nil {
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ch = bp.blockingCh
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}
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if ch == bp.blockingCh {
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// This could happen when either:
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// - bp.picker is nil (the previous if condition), or
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// - has called pick on the current picker.
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bp.mu.Unlock()
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select {
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case <-ctx.Done():
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return nil, nil, ctx.Err()
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case <-ch:
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}
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continue
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}
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ch = bp.blockingCh
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p := bp.picker
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bp.mu.Unlock()
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subConn, done, err := p.Pick(ctx, opts)
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if err != nil {
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switch err {
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case balancer.ErrNoSubConnAvailable:
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continue
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case balancer.ErrTransientFailure:
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if !failfast {
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continue
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}
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return nil, nil, status.Errorf(codes.Unavailable, "%v, latest connection error: %v", err, bp.connectionError())
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case context.DeadlineExceeded:
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return nil, nil, status.Error(codes.DeadlineExceeded, err.Error())
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case context.Canceled:
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return nil, nil, status.Error(codes.Canceled, err.Error())
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default:
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if _, ok := status.FromError(err); ok {
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return nil, nil, err
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}
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// err is some other error.
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return nil, nil, status.Error(codes.Unknown, err.Error())
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}
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}
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acw, ok := subConn.(*acBalancerWrapper)
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if !ok {
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grpclog.Error("subconn returned from pick is not *acBalancerWrapper")
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continue
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}
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if t, ok := acw.getAddrConn().getReadyTransport(); ok {
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if channelz.IsOn() {
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return t, doneChannelzWrapper(acw, done), nil
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}
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return t, done, nil
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}
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if done != nil {
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// Calling done with nil error, no bytes sent and no bytes received.
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// DoneInfo with default value works.
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done(balancer.DoneInfo{})
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}
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grpclog.Infof("blockingPicker: the picked transport is not ready, loop back to repick")
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// If ok == false, ac.state is not READY.
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// A valid picker always returns READY subConn. This means the state of ac
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// just changed, and picker will be updated shortly.
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// continue back to the beginning of the for loop to repick.
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}
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}
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func (bp *pickerWrapper) close() {
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bp.mu.Lock()
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defer bp.mu.Unlock()
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if bp.done {
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return
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}
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bp.done = true
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close(bp.blockingCh)
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}
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