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194 lines
4.7 KiB
Go
Vendored
194 lines
4.7 KiB
Go
Vendored
// Copyright 2020 Andrew Thornton. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package levelqueue
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import (
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"fmt"
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"github.com/syndtr/goleveldb/leveldb"
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"github.com/syndtr/goleveldb/leveldb/errors"
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)
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const (
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uniqueQueuePrefixStr = "unique"
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)
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// UniqueQueue defines an unique queue struct
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type UniqueQueue struct {
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q *Queue
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set *Set
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db *leveldb.DB
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closeUnderlyingDB bool
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}
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// OpenUnique opens an unique queue from the db path or creates a set if it doesn't exist.
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// The keys in the queue portion will not be prefixed, and the set keys will be prefixed with "set-"
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func OpenUnique(dataDir string) (*UniqueQueue, error) {
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db, err := leveldb.OpenFile(dataDir, nil)
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if err != nil {
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if !errors.IsCorrupted(err) {
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return nil, err
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}
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db, err = leveldb.RecoverFile(dataDir, nil)
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if err != nil {
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return nil, err
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}
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}
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return NewUniqueQueue(db, []byte{}, []byte(uniqueQueuePrefixStr), true)
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}
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// NewUniqueQueue creates a new unique queue from a db.
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// The queue keys will be prefixed with queuePrefix and the set keys with setPrefix
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// and at close the db will be closed as per closeUnderlyingDB
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func NewUniqueQueue(db *leveldb.DB, queuePrefix []byte, setPrefix []byte, closeUnderlyingDB bool) (*UniqueQueue, error) {
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internal, err := NewQueue(db, queuePrefix, false)
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if err != nil {
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return nil, err
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}
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set, err := NewSet(db, setPrefix, false)
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if err != nil {
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return nil, err
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}
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queue := &UniqueQueue{
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q: internal,
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set: set,
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db: db,
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closeUnderlyingDB: closeUnderlyingDB,
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}
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return queue, err
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}
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// LPush pushes data to the left of the queue
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func (queue *UniqueQueue) LPush(data []byte) error {
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return queue.LPushFunc(data, nil)
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}
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// LPushFunc pushes data to the left of the queue and calls the callback if it is added
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func (queue *UniqueQueue) LPushFunc(data []byte, fn func() error) error {
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added, err := queue.set.Add(data)
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if err != nil {
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return err
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}
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if !added {
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return ErrAlreadyInQueue
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}
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if fn != nil {
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err = fn()
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if err != nil {
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_, remErr := queue.set.Remove(data)
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if remErr != nil {
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return fmt.Errorf("%v & %v", err, remErr)
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}
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return err
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}
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}
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return queue.q.LPush(data)
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}
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// RPush pushes data to the right of the queue
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func (queue *UniqueQueue) RPush(data []byte) error {
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return queue.RPushFunc(data, nil)
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}
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// RPushFunc pushes data to the right of the queue and calls the callback if is added
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func (queue *UniqueQueue) RPushFunc(data []byte, fn func() error) error {
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added, err := queue.set.Add(data)
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if err != nil {
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return err
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}
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if !added {
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return ErrAlreadyInQueue
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}
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if fn != nil {
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err = fn()
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if err != nil {
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_, remErr := queue.set.Remove(data)
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if remErr != nil {
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return fmt.Errorf("%v & %v", err, remErr)
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}
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return err
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}
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}
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return queue.q.RPush(data)
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}
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// RPop pop data from the right of the queue
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func (queue *UniqueQueue) RPop() ([]byte, error) {
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popped, err := queue.q.RPop()
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if err != nil {
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return popped, err
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}
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_, err = queue.set.Remove(popped)
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return popped, err
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}
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// RHandle receives a user callback function to handle the right element of the queue, if the function returns nil, then delete the element, otherwise keep the element.
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func (queue *UniqueQueue) RHandle(h func([]byte) error) error {
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return queue.q.RHandle(func(data []byte) error {
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err := h(data)
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if err != nil {
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return err
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}
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_, err = queue.set.Remove(data)
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return err
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})
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}
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// LPop pops data from left of the queue
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func (queue *UniqueQueue) LPop() ([]byte, error) {
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popped, err := queue.q.LPop()
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if err != nil {
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return popped, err
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}
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_, err = queue.set.Remove(popped)
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return popped, err
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}
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// LHandle receives a user callback function to handle the left element of the queue, if the function returns nil, then delete the element, otherwise keep the element.
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func (queue *UniqueQueue) LHandle(h func([]byte) error) error {
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return queue.q.LHandle(func(data []byte) error {
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err := h(data)
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if err != nil {
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return err
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}
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_, err = queue.set.Remove(data)
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return err
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})
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}
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// Has checks whether the data is already in the queue
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func (queue *UniqueQueue) Has(data []byte) (bool, error) {
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return queue.set.Has(data)
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}
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// Len returns the length of the queue
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func (queue *UniqueQueue) Len() int64 {
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queue.set.lock.Lock()
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defer queue.set.lock.Unlock()
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return queue.q.Len()
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}
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// Close closes the queue (and the underlying DB if set to closeUnderlyingDB)
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func (queue *UniqueQueue) Close() error {
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_ = queue.q.Close()
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_ = queue.set.Close()
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queue.set.lock.Lock()
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defer queue.set.lock.Unlock()
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if !queue.closeUnderlyingDB {
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queue.db = nil
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return nil
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}
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err := queue.db.Close()
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queue.db = nil
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return err
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}
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