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- // Copyright 2017 Google Inc. All rights reserved.
- //
- // 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 build
- import (
- "errors"
- "fmt"
- "math"
- "os"
- "path/filepath"
- "syscall"
- "time"
- "android/soong/ui/logger"
- )
- // This file provides cross-process synchronization methods
- // i.e. making sure only one Soong process is running for a given output directory
- func BecomeSingletonOrFail(ctx Context, config Config) (lock *fileLock) {
- lockingInfo, err := newLock(config.OutDir())
- if err != nil {
- ctx.Logger.Fatal(err)
- }
- lockfilePollDuration := time.Second
- lockfileTimeout := time.Second * 10
- if envTimeout := os.Getenv("SOONG_LOCK_TIMEOUT"); envTimeout != "" {
- lockfileTimeout, err = time.ParseDuration(envTimeout)
- if err != nil {
- ctx.Logger.Fatalf("failure parsing SOONG_LOCK_TIMEOUT %q: %s", envTimeout, err)
- }
- }
- err = lockSynchronous(*lockingInfo, newSleepWaiter(lockfilePollDuration, lockfileTimeout), ctx.Logger)
- if err != nil {
- ctx.Logger.Fatal(err)
- }
- return lockingInfo
- }
- type lockable interface {
- tryLock() error
- Unlock() error
- description() string
- }
- var _ lockable = (*fileLock)(nil)
- type fileLock struct {
- File *os.File
- }
- func (l fileLock) description() (path string) {
- return l.File.Name()
- }
- func (l fileLock) tryLock() (err error) {
- return syscall.Flock(int(l.File.Fd()), syscall.LOCK_EX|syscall.LOCK_NB)
- }
- func (l fileLock) Unlock() (err error) {
- return l.File.Close()
- }
- func lockSynchronous(lock lockable, waiter waiter, logger logger.Logger) (err error) {
- waited := false
- for {
- err = lock.tryLock()
- if err == nil {
- if waited {
- // If we had to wait at all, then when the wait is done, we inform the user
- logger.Printf("Acquired lock on %v; previous Soong process must have completed. Continuing...\n", lock.description())
- }
- return nil
- }
- done, description := waiter.checkDeadline()
- if !waited {
- logger.Printf("Waiting up to %s to lock %v to ensure no other Soong process is running in the same output directory\n", description, lock.description())
- }
- waited = true
- if done {
- return fmt.Errorf("Tried to lock %s, but timed out %s . Make sure no other Soong process is using it",
- lock.description(), waiter.summarize())
- } else {
- waiter.wait()
- }
- }
- }
- func newLock(basedir string) (lock *fileLock, err error) {
- lockPath := filepath.Join(basedir, ".lock")
- os.MkdirAll(basedir, 0777)
- lockfileDescriptor, err := os.OpenFile(lockPath, os.O_RDWR|os.O_CREATE, 0666)
- if err != nil {
- return nil, errors.New("failed to open " + lockPath)
- }
- lockingInfo := &fileLock{File: lockfileDescriptor}
- return lockingInfo, nil
- }
- type waiter interface {
- wait()
- checkDeadline() (done bool, remainder string)
- summarize() (summary string)
- }
- type sleepWaiter struct {
- sleepInterval time.Duration
- deadline time.Time
- totalWait time.Duration
- }
- var _ waiter = (*sleepWaiter)(nil)
- func newSleepWaiter(interval time.Duration, duration time.Duration) (waiter *sleepWaiter) {
- return &sleepWaiter{interval, time.Now().Add(duration), duration}
- }
- func (s sleepWaiter) wait() {
- time.Sleep(s.sleepInterval)
- }
- func (s *sleepWaiter) checkDeadline() (done bool, remainder string) {
- remainingSleep := s.deadline.Sub(time.Now())
- numSecondsRounded := math.Floor(remainingSleep.Seconds()*10+0.5) / 10
- if remainingSleep > 0 {
- return false, fmt.Sprintf("%vs", numSecondsRounded)
- } else {
- return true, ""
- }
- }
- func (s sleepWaiter) summarize() (summary string) {
- return fmt.Sprintf("polling every %v until %v", s.sleepInterval, s.totalWait)
- }
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