80 lines
1.8 KiB
Go
80 lines
1.8 KiB
Go
//go:build unix
|
|
|
|
package cli
|
|
|
|
import (
|
|
"context"
|
|
"errors"
|
|
"fmt"
|
|
"os"
|
|
"time"
|
|
|
|
"golang.org/x/sys/unix"
|
|
)
|
|
|
|
func acquireSyncLock(ctx context.Context, path string) (func() error, error) {
|
|
file, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0o600)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("open sync lock: %w", err)
|
|
}
|
|
locked := false
|
|
defer func() {
|
|
if !locked {
|
|
_ = file.Close()
|
|
}
|
|
}()
|
|
ticker := time.NewTicker(200 * time.Millisecond)
|
|
defer ticker.Stop()
|
|
for {
|
|
err = unix.Flock(int(file.Fd()), unix.LOCK_EX|unix.LOCK_NB)
|
|
if err == nil {
|
|
locked = true
|
|
_, _ = file.Seek(0, 0)
|
|
_ = file.Truncate(0)
|
|
_, _ = fmt.Fprintf(file, "pid=%d\n", os.Getpid())
|
|
return func() error {
|
|
unlockErr := unix.Flock(int(file.Fd()), unix.LOCK_UN)
|
|
closeErr := file.Close()
|
|
if unlockErr != nil {
|
|
return unlockErr
|
|
}
|
|
return closeErr
|
|
}, nil
|
|
}
|
|
if !errors.Is(err, unix.EWOULDBLOCK) && !errors.Is(err, unix.EAGAIN) {
|
|
return nil, fmt.Errorf("acquire sync lock: %w", err)
|
|
}
|
|
select {
|
|
case <-ctx.Done():
|
|
return nil, syncLockErr(ctx, path)
|
|
case <-ticker.C:
|
|
}
|
|
}
|
|
}
|
|
|
|
func tryAcquireSyncLock(path string) (func() error, bool, error) {
|
|
file, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0o600)
|
|
if err != nil {
|
|
return nil, false, fmt.Errorf("open sync lock: %w", err)
|
|
}
|
|
err = unix.Flock(int(file.Fd()), unix.LOCK_EX|unix.LOCK_NB)
|
|
if err != nil {
|
|
_ = file.Close()
|
|
if errors.Is(err, unix.EWOULDBLOCK) || errors.Is(err, unix.EAGAIN) {
|
|
return nil, false, nil
|
|
}
|
|
return nil, false, fmt.Errorf("acquire sync lock: %w", err)
|
|
}
|
|
_, _ = file.Seek(0, 0)
|
|
_ = file.Truncate(0)
|
|
_, _ = fmt.Fprintf(file, "pid=%d\n", os.Getpid())
|
|
return func() error {
|
|
unlockErr := unix.Flock(int(file.Fd()), unix.LOCK_UN)
|
|
closeErr := file.Close()
|
|
if unlockErr != nil {
|
|
return unlockErr
|
|
}
|
|
return closeErr
|
|
}, true, nil
|
|
}
|