77 lines
1.9 KiB
Go
77 lines
1.9 KiB
Go
// lock logic heavily inspired by go-ipfs/repo/fsrepo/lock/lock.go
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package main
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import (
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"fmt"
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"io"
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"os"
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"path"
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fslock "github.com/ipfs/go-fs-lock"
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)
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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 procees 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() error {
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if l.lockCloser != nil {
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return fmt.Errorf("cannot acquire lock twice")
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}
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if err := l.checkConfigExists(); err != nil {
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return err
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}
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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 := fmt.Sprintf(`could not obtain execution lock. If no other process
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is running, remove %s, or make sure that the config folder is
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writable for the user running ipfs-cluster. Run with -d for more information
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about the error`, path.Join(l.path, lockFileName))
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logger.Error(errStr)
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return fmt.Errorf("could not obtain execution lock")
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}
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logger.Debug("Success! ipfs-cluster-service lock acquired")
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l.lockCloser = lk
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return nil
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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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func (l *lock) checkConfigExists() error {
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if _, err := os.Stat(l.path); os.IsNotExist(err) {
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logger.Error("ipfs-cluster-service config hasn't been initialized.\nPlease run ipfs-cluster-service init")
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return err
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}
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if _, err := os.Stat(fmt.Sprintf("%s/%s", l.path, "service.json")); os.IsNotExist(err) {
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logger.Error("ipfs-cluster-service config hasn't been initialized.\nPlease run ipfs-cluster-service init")
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return err
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}
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return nil
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}
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