72 lines
1.6 KiB
Go
72 lines
1.6 KiB
Go
package main
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import (
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"errors"
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"fmt"
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"io"
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"path"
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fslock "github.com/ipfs/go-fs-lock"
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"github.com/ipfs-cluster/ipfs-cluster/cmdutils"
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)
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// lock logic heavily inspired by go-ipfs/repo/fsrepo/lock/lock.go
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// The name of the file used for locking
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const lockFileName = "cluster.lock"
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var locker *lock
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// lock helps to coordinate proceeds via a lock file
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type lock struct {
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lockCloser io.Closer
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path string
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}
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func (l *lock) lock() {
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if l.lockCloser != nil {
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checkErr("", errors.New("cannot acquire lock twice"))
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}
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// we should have a config folder whenever we try to lock
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cfgHelper := cmdutils.NewConfigHelper(configPath, identityPath, "", "")
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cfgHelper.MakeConfigFolder()
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// set the lock file within this function
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logger.Debug("checking lock")
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lk, err := fslock.Lock(l.path, lockFileName)
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if err != nil {
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logger.Debug(err)
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l.lockCloser = nil
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errStr := "%s. If no other "
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errStr += "%s process is running, remove %s, or make sure "
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errStr += "that the config folder is writable for the user "
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errStr += "running %s."
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errStr = fmt.Sprintf(
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errStr,
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err,
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programName,
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path.Join(l.path, lockFileName),
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programName,
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)
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checkErr("obtaining execution lock", errors.New(errStr))
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}
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logger.Debugf("%s execution lock acquired", programName)
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l.lockCloser = lk
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}
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func (l *lock) tryUnlock() error {
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// Noop in the uninitialized case
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if l.lockCloser == nil {
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logger.Debug("locking not initialized, unlock is noop")
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return nil
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}
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err := l.lockCloser.Close()
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if err != nil {
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return err
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}
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logger.Debug("successfully released execution lock")
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l.lockCloser = nil
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return nil
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}
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