| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 nmxutil |
| |
| import ( |
| "fmt" |
| "sync" |
| "time" |
| ) |
| |
| // Blocks a variable number of waiters until Unblock() is called. Subsequent |
| // waiters are unblocked until the next call to Block(). |
| type Blocker struct { |
| ch chan struct{} |
| mtx sync.Mutex |
| val interface{} |
| } |
| |
| func (b *Blocker) unblockNoLock(val interface{}) { |
| if b.ch != nil { |
| b.val = val |
| close(b.ch) |
| b.ch = nil |
| } |
| } |
| |
| func (b *Blocker) startNoLock() { |
| if b.ch == nil { |
| b.ch = make(chan struct{}) |
| } |
| } |
| |
| func (b *Blocker) Started() bool { |
| b.mtx.Lock() |
| defer b.mtx.Unlock() |
| |
| return b.ch != nil |
| } |
| |
| func (b *Blocker) Wait(timeout time.Duration, stopChan <-chan struct{}) ( |
| interface{}, error) { |
| |
| b.mtx.Lock() |
| ch := b.ch |
| b.mtx.Unlock() |
| |
| if ch == nil { |
| return b.val, nil |
| } |
| |
| if stopChan == nil { |
| stopChan = make(chan struct{}) |
| } |
| |
| timer := time.NewTimer(timeout) |
| select { |
| case <-ch: |
| StopAndDrainTimer(timer) |
| return b.val, nil |
| case <-timer.C: |
| return nil, fmt.Errorf("timeout after %s", timeout.String()) |
| case <-stopChan: |
| return nil, fmt.Errorf("aborted") |
| } |
| } |
| |
| func (b *Blocker) Start() { |
| b.mtx.Lock() |
| defer b.mtx.Unlock() |
| |
| b.startNoLock() |
| } |
| |
| func (b *Blocker) Unblock(val interface{}) { |
| b.mtx.Lock() |
| defer b.mtx.Unlock() |
| |
| b.unblockNoLock(val) |
| } |
| |
| func (b *Blocker) UnblockAndRestart(val interface{}) { |
| b.mtx.Lock() |
| defer b.mtx.Unlock() |
| |
| b.unblockNoLock(val) |
| b.startNoLock() |
| } |