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