Add Unique Queue infrastructure and move TestPullRequests to this (#9856)

* Upgrade levelqueue to version 0.2.0

This adds functionality for Unique Queues

* Add UniqueQueue interface and functions to create them

* Add UniqueQueue implementations

* Move TestPullRequests over to use UniqueQueue

* Reduce code duplication

* Add bytefifos

* Ensure invalid types are logged

* Fix close race in PersistableChannelQueue Shutdown

vendor/gitea.com/lunny/levelqueue/uniquequeue.go

@@ -0,0 +1,184 @@
+// Copyright 2020 Andrew Thornton. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package levelqueue
+
+import (
+	"fmt"
+
+	"github.com/syndtr/goleveldb/leveldb"
+)
+
+const (
+	uniqueQueuePrefixStr = "unique"
+)
+
+// UniqueQueue defines an unique queue struct
+type UniqueQueue struct {
+	q                 *Queue
+	set               *Set
+	db                *leveldb.DB
+	closeUnderlyingDB bool
+}
+
+// OpenUnique opens an unique queue from the db path or creates a set if it doesn't exist.
+// The keys in the queue portion will not be prefixed, and the set keys will be prefixed with "set-"
+func OpenUnique(dataDir string) (*UniqueQueue, error) {
+	db, err := leveldb.OpenFile(dataDir, nil)
+	if err != nil {
+		return nil, err
+	}
+	return NewUniqueQueue(db, []byte{}, []byte(uniqueQueuePrefixStr), true)
+}
+
+// NewUniqueQueue creates a new unique queue from a db.
+// The queue keys will be prefixed with queuePrefix and the set keys with setPrefix
+// and at close the db will be closed as per closeUnderlyingDB
+func NewUniqueQueue(db *leveldb.DB, queuePrefix []byte, setPrefix []byte, closeUnderlyingDB bool) (*UniqueQueue, error) {
+	internal, err := NewQueue(db, queuePrefix, false)
+	if err != nil {
+		return nil, err
+	}
+	set, err := NewSet(db, setPrefix, false)
+	if err != nil {
+		return nil, err
+	}
+	queue := &UniqueQueue{
+		q:                 internal,
+		set:               set,
+		db:                db,
+		closeUnderlyingDB: closeUnderlyingDB,
+	}
+
+	return queue, err
+}
+
+// LPush pushes data to the left of the queue
+func (queue *UniqueQueue) LPush(data []byte) error {
+	return queue.LPushFunc(data, nil)
+}
+
+// LPushFunc pushes data to the left of the queue and calls the callback if it is added
+func (queue *UniqueQueue) LPushFunc(data []byte, fn func() error) error {
+	added, err := queue.set.Add(data)
+	if err != nil {
+		return err
+	}
+	if !added {
+		return ErrAlreadyInQueue
+	}
+
+	if fn != nil {
+		err = fn()
+		if err != nil {
+			_, remErr := queue.set.Remove(data)
+			if remErr != nil {
+				return fmt.Errorf("%v & %v", err, remErr)
+			}
+			return err
+		}
+	}
+
+	return queue.q.LPush(data)
+}
+
+// RPush pushes data to the right of the queue
+func (queue *UniqueQueue) RPush(data []byte) error {
+	return queue.RPushFunc(data, nil)
+}
+
+// RPushFunc pushes data to the right of the queue and calls the callback if is added
+func (queue *UniqueQueue) RPushFunc(data []byte, fn func() error) error {
+	added, err := queue.set.Add(data)
+	if err != nil {
+		return err
+	}
+	if !added {
+		return ErrAlreadyInQueue
+	}
+
+	if fn != nil {
+		err = fn()
+		if err != nil {
+			_, remErr := queue.set.Remove(data)
+			if remErr != nil {
+				return fmt.Errorf("%v & %v", err, remErr)
+			}
+			return err
+		}
+	}
+
+	return queue.q.RPush(data)
+}
+
+// RPop pop data from the right of the queue
+func (queue *UniqueQueue) RPop() ([]byte, error) {
+	popped, err := queue.q.RPop()
+	if err != nil {
+		return popped, err
+	}
+	_, err = queue.set.Remove(popped)
+
+	return popped, err
+}
+
+// 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.
+func (queue *UniqueQueue) RHandle(h func([]byte) error) error {
+	return queue.q.RHandle(func(data []byte) error {
+		err := h(data)
+		if err != nil {
+			return err
+		}
+		_, err = queue.set.Remove(data)
+		return err
+	})
+}
+
+// LPop pops data from left of the queue
+func (queue *UniqueQueue) LPop() ([]byte, error) {
+	popped, err := queue.q.LPop()
+	if err != nil {
+		return popped, err
+	}
+	_, err = queue.set.Remove(popped)
+
+	return popped, err
+}
+
+// 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.
+func (queue *UniqueQueue) LHandle(h func([]byte) error) error {
+	return queue.q.LHandle(func(data []byte) error {
+		err := h(data)
+		if err != nil {
+			return err
+		}
+		_, err = queue.set.Remove(data)
+		return err
+	})
+}
+
+// Has checks whether the data is already in the queue
+func (queue *UniqueQueue) Has(data []byte) (bool, error) {
+	return queue.set.Has(data)
+}
+
+// Len returns the length of the queue
+func (queue *UniqueQueue) Len() int64 {
+	queue.set.lock.Lock()
+	defer queue.set.lock.Unlock()
+	return queue.q.Len()
+}
+
+// Close closes the queue (and the underlying DB if set to closeUnderlyingDB)
+func (queue *UniqueQueue) Close() error {
+	_ = queue.q.Close()
+	_ = queue.set.Close()
+	if !queue.closeUnderlyingDB {
+		queue.db = nil
+		return nil
+	}
+	err := queue.db.Close()
+	queue.db = nil
+	return err
+}