New value defaults to 100K events by default, but users can tune this value upto any value they seem necessary. * increase the limit to maxint64 while validating
207 lines
4.4 KiB
Go
207 lines
4.4 KiB
Go
/*
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* MinIO Cloud Storage, (C) 2019 MinIO, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package target
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import (
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"encoding/json"
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"io/ioutil"
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"math"
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"os"
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"path/filepath"
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"sort"
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"sync"
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"github.com/minio/minio/pkg/event"
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"github.com/minio/minio/pkg/sys"
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)
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const (
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defaultLimit = 100000 // Default store limit.
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eventExt = ".event"
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)
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// QueueStore - Filestore for persisting events.
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type QueueStore struct {
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sync.RWMutex
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currentEntries uint64
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entryLimit uint64
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directory string
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}
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// NewQueueStore - Creates an instance for QueueStore.
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func NewQueueStore(directory string, limit uint64) Store {
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if limit == 0 {
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limit = defaultLimit
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_, maxRLimit, err := sys.GetMaxOpenFileLimit()
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if err == nil {
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// Limit the maximum number of entries
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// to maximum open file limit
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if maxRLimit < limit {
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limit = maxRLimit
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}
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}
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}
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return &QueueStore{
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directory: directory,
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entryLimit: limit,
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}
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}
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// Open - Creates the directory if not present.
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func (store *QueueStore) Open() error {
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store.Lock()
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defer store.Unlock()
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if err := os.MkdirAll(store.directory, os.FileMode(0770)); err != nil {
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return err
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}
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names, err := store.list()
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if err != nil {
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return err
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}
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currentEntries := uint64(len(names))
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if currentEntries >= store.entryLimit {
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return errLimitExceeded
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}
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store.currentEntries = currentEntries
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return nil
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}
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// write - writes event to the directory.
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func (store *QueueStore) write(key string, e event.Event) error {
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// Marshalls the event.
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eventData, err := json.Marshal(e)
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if err != nil {
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return err
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}
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path := filepath.Join(store.directory, key+eventExt)
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if err := ioutil.WriteFile(path, eventData, os.FileMode(0770)); err != nil {
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return err
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}
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// Increment the event count.
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store.currentEntries++
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return nil
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}
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// Put - puts a event to the store.
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func (store *QueueStore) Put(e event.Event) error {
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store.Lock()
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defer store.Unlock()
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if store.currentEntries >= store.entryLimit {
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return errLimitExceeded
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}
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key, err := getNewUUID()
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if err != nil {
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return err
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}
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return store.write(key, e)
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}
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// Get - gets a event from the store.
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func (store *QueueStore) Get(key string) (event event.Event, err error) {
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store.RLock()
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defer func(store *QueueStore) {
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store.RUnlock()
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if err != nil {
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// Upon error we remove the entry.
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store.Del(key)
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}
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}(store)
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var eventData []byte
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eventData, err = ioutil.ReadFile(filepath.Join(store.directory, key+eventExt))
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if err != nil {
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return event, err
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}
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if len(eventData) == 0 {
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return event, os.ErrNotExist
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}
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if err = json.Unmarshal(eventData, &event); err != nil {
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return event, err
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}
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return event, nil
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}
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// Del - Deletes an entry from the store.
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func (store *QueueStore) Del(key string) error {
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store.Lock()
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defer store.Unlock()
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return store.del(key)
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}
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// lockless call
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func (store *QueueStore) del(key string) error {
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if err := os.Remove(filepath.Join(store.directory, key+eventExt)); err != nil {
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return err
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}
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// Decrement the current entries count.
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store.currentEntries--
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// Current entries can underflow, when multiple
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// events are being pushed in parallel, this code
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// is needed to ensure that we don't underflow.
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//
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// queueStore replayEvents is not serialized,
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// this code is needed to protect us under
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// such situations.
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if store.currentEntries == math.MaxUint64 {
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store.currentEntries = 0
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}
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return nil
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}
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// List - lists all files from the directory.
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func (store *QueueStore) List() ([]string, error) {
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store.RLock()
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defer store.RUnlock()
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return store.list()
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}
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// list lock less.
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func (store *QueueStore) list() ([]string, error) {
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var names []string
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files, err := ioutil.ReadDir(store.directory)
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if err != nil {
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return names, err
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}
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// Sort the dentries.
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sort.Slice(files, func(i, j int) bool {
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return files[i].ModTime().Before(files[j].ModTime())
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})
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for _, file := range files {
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names = append(names, file.Name())
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}
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return names, nil
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}
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