tusd/memorylocker/memorylocker.go

54 lines
1.6 KiB
Go

// Package memorylocker provides an in-memory locking mechanism
//
// When multiple processes are attempting to access an upload, whether it be
// by reading or writing, a syncronization mechanism is required to prevent
// data corruption, especially to ensure correct offset values and the proper
// order of chunks inside a single upload.
//
// MemoryLocker persists locks using memory and therefore allowing a simple and
// cheap mechansim. Locks will only exist as long as this object is kept in
// reference and will be erased if the program exits.
package memorylocker
import (
"github.com/tus/tusd"
)
// MemoryLocker persists locks using memory and therefore allowing a simple and
// cheap mechansim. Locks will only exist as long as this object is kept in
// reference and will be erased if the program exits.
type MemoryLocker struct {
tusd.DataStore
locks map[string]bool
}
// New creates a new lock memory wrapper around the provided storage.
func NewMemoryLocker(store tusd.DataStore) *MemoryLocker {
return &MemoryLocker{
DataStore: store,
locks: make(map[string]bool),
}
}
// LockUpload tries to obtain the exclusive lock.
func (locker *MemoryLocker) LockUpload(id string) error {
// Ensure file is not locked
if _, ok := locker.locks[id]; ok {
return tusd.ErrFileLocked
}
locker.locks[id] = true
return nil
}
// UnlockUpload releases a lock. If no such lock exists, no error will be returned.
func (locker *MemoryLocker) UnlockUpload(id string) error {
// Deleting a non-existing key does not end in unexpected errors or panic
// since this operation results in a no-op
delete(locker.locks, id)
return nil
}