Queue: Add generic graceful queues with settings

modules/queue/queue_disk.go

@@ -0,0 +1,158 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package queue
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"reflect"
+	"time"
+
+	"code.gitea.io/gitea/modules/log"
+
+	"gitea.com/lunny/levelqueue"
+)
+
+// LevelQueueType is the type for level queue
+const LevelQueueType Type = "level"
+
+// LevelQueueConfiguration is the configuration for a LevelQueue
+type LevelQueueConfiguration struct {
+	DataDir     string
+	BatchLength int
+}
+
+// LevelQueue implements a disk library queue
+type LevelQueue struct {
+	handle      HandlerFunc
+	queue       *levelqueue.Queue
+	batchLength int
+	closed      chan struct{}
+	exemplar    interface{}
+}
+
+// NewLevelQueue creates a ledis local queue
+func NewLevelQueue(handle HandlerFunc, cfg, exemplar interface{}) (Queue, error) {
+	configInterface, err := toConfig(LevelQueueConfiguration{}, cfg)
+	if err != nil {
+		return nil, err
+	}
+	config := configInterface.(LevelQueueConfiguration)
+
+	queue, err := levelqueue.Open(config.DataDir)
+	if err != nil {
+		return nil, err
+	}
+
+	return &LevelQueue{
+		handle:      handle,
+		queue:       queue,
+		batchLength: config.BatchLength,
+		exemplar:    exemplar,
+		closed:      make(chan struct{}),
+	}, nil
+}
+
+// Run starts to run the queue
+func (l *LevelQueue) Run(atShutdown, atTerminate func(context.Context, func())) {
+	atShutdown(context.Background(), l.Shutdown)
+	atTerminate(context.Background(), l.Terminate)
+	var i int
+	var datas = make([]Data, 0, l.batchLength)
+	for {
+		select {
+		case <-l.closed:
+			if len(datas) > 0 {
+				log.Trace("Handling: %d data, %v", len(datas), datas)
+				l.handle(datas...)
+			}
+			return
+		default:
+		}
+		i++
+		if len(datas) > l.batchLength || (len(datas) > 0 && i > 3) {
+			log.Trace("Handling: %d data, %v", len(datas), datas)
+			l.handle(datas...)
+			datas = make([]Data, 0, l.batchLength)
+			i = 0
+			continue
+		}
+
+		bs, err := l.queue.RPop()
+		if err != nil {
+			if err != levelqueue.ErrNotFound {
+				log.Error("RPop: %v", err)
+			}
+			time.Sleep(time.Millisecond * 100)
+			continue
+		}
+
+		if len(bs) == 0 {
+			time.Sleep(time.Millisecond * 100)
+			continue
+		}
+
+		var data Data
+		if l.exemplar != nil {
+			t := reflect.TypeOf(l.exemplar)
+			n := reflect.New(t)
+			ne := n.Elem()
+			err = json.Unmarshal(bs, ne.Addr().Interface())
+			data = ne.Interface().(Data)
+		} else {
+			err = json.Unmarshal(bs, &data)
+		}
+		if err != nil {
+			log.Error("Unmarshal: %v", err)
+			time.Sleep(time.Millisecond * 10)
+			continue
+		}
+
+		log.Trace("LevelQueue: task found: %#v", data)
+
+		datas = append(datas, data)
+	}
+}
+
+// Push will push the indexer data to queue
+func (l *LevelQueue) Push(data Data) error {
+	if l.exemplar != nil {
+		// Assert data is of same type as r.exemplar
+		value := reflect.ValueOf(data)
+		t := value.Type()
+		exemplarType := reflect.ValueOf(l.exemplar).Type()
+		if !t.AssignableTo(exemplarType) || data == nil {
+			return fmt.Errorf("Unable to assign data: %v to same type as exemplar: %v in %s", data, l.exemplar, l.name)
+		}
+	}
+	bs, err := json.Marshal(data)
+	if err != nil {
+		return err
+	}
+	return l.queue.LPush(bs)
+}
+
+// Shutdown this queue and stop processing
+func (l *LevelQueue) Shutdown() {
+	select {
+	case <-l.closed:
+	default:
+		close(l.closed)
+	}
+}
+
+// Terminate this queue and close the queue
+func (l *LevelQueue) Terminate() {
+	l.Shutdown()
+	if err := l.queue.Close(); err != nil && err.Error() != "leveldb: closed" {
+		log.Error("Error whilst closing internal queue: %v", err)
+	}
+
+}
+
+func init() {
+	queuesMap[LevelQueueType] = NewLevelQueue
+}