141 lines
3.8 KiB
Go
141 lines
3.8 KiB
Go
// Package limitedstore provides a storage with a limited space.
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//
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// This goal is achieved by using a simple wrapper around existing
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// datastores (tusd.DataStore) while limiting the used storage size.
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// It will start terminating existing uploads if not enough space is left in
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// order to create a new upload.
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// The order in which the uploads will be terminated is defined by their size,
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// whereas the biggest ones are deleted first.
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// This package's functionality is very limited and naive. It will terminate
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// uploads whether they are finished yet or not. Only one datastore is allowed to
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// access the underlying storage else the limited store will not function
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// properly. Two tusd.FileStore instances using the same directory, for example.
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// In addition the limited store will keep a list of the uploads' IDs in memory
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// which may create a growing memory leak.
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package limitedstore
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import (
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"os"
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"sort"
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"sync"
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"github.com/tus/tusd"
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)
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type LimitedStore struct {
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tusd.DataStore
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terminater tusd.TerminaterDataStore
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StoreSize int64
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uploads map[string]int64
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usedSize int64
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mutex *sync.Mutex
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}
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// pair structure to perform map-sorting
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type pair struct {
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key string
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value int64
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}
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type pairlist []pair
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func (p pairlist) Len() int { return len(p) }
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func (p pairlist) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
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func (p pairlist) Less(i, j int) bool { return p[i].value < p[j].value }
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// New creates a new limited store with the given size as the maximum storage
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// size. The wrapped data store needs to implement the TerminaterDataStore
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// interface, in order to provide the required Terminate method.
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func New(storeSize int64, dataStore tusd.DataStore, terminater tusd.TerminaterDataStore) *LimitedStore {
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return &LimitedStore{
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StoreSize: storeSize,
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DataStore: dataStore,
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terminater: terminater,
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uploads: make(map[string]int64),
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mutex: new(sync.Mutex),
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}
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}
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func (store *LimitedStore) UseIn(composer *tusd.StoreComposer) {
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composer.UseCore(store)
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composer.UseTerminater(store)
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}
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func (store *LimitedStore) NewUpload(info tusd.FileInfo) (string, error) {
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store.mutex.Lock()
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defer store.mutex.Unlock()
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if err := store.ensureSpace(info.Size); err != nil {
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return "", err
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}
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id, err := store.DataStore.NewUpload(info)
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if err != nil {
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return "", err
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}
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store.usedSize += info.Size
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store.uploads[id] = info.Size
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return id, nil
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}
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func (store *LimitedStore) Terminate(id string) error {
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store.mutex.Lock()
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defer store.mutex.Unlock()
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return store.terminate(id)
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}
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func (store *LimitedStore) terminate(id string) error {
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err := store.terminater.Terminate(id)
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// Ignore the error if the upload could not be found. In this case, the upload
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// has likely already been removed by another service (e.g. a cron job) and we
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// just remove the upload from our internal list and claim the used space back.
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if err != nil && err != tusd.ErrNotFound && !os.IsNotExist(err) {
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return err
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}
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size := store.uploads[id]
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delete(store.uploads, id)
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store.usedSize -= size
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return nil
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}
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// Ensure enough space is available to store an upload of the specified size.
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// It will terminate uploads until enough space is freed.
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func (store *LimitedStore) ensureSpace(size int64) error {
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if (store.usedSize + size) <= store.StoreSize {
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// Enough space is available to store the new upload
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return nil
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}
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sortedUploads := make(pairlist, len(store.uploads))
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i := 0
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for u, h := range store.uploads {
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sortedUploads[i] = pair{u, h}
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i++
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}
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sort.Sort(sort.Reverse(sortedUploads))
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// Forward traversal through the uploads in terms of size, biggest upload first
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for _, k := range sortedUploads {
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id := k.key
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if err := store.terminate(id); err != nil {
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return err
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}
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if (store.usedSize + size) <= store.StoreSize {
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// Enough space has been freed to store the new upload
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return nil
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}
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}
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return nil
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}
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