import redis

# 實例化一個redis連接池
pool = redis.ConnectionPool(host='127.0.0.1', port=6379, decode_responses=True, db=4, password='')

r = redis.Redis(connection_pool=pool)
# 爬蟲實例限制為4 即只允許4個scrapy實例在運行
limited = 4

# 聲明redis的樂觀鎖
lock = r.Lock()

# lock.acquire中有while循環，即它會線程阻塞，直到當前線程獲得redis的lock，才會繼續往下執行代碼
if lock.acquire():
	# 1、從reids中取一條爬蟲信息
	info = redis.get() 
	
	# 2、while循環監聽爬蟲運行的數量
	while True:
		req = requests.get('http://127.0.0.1:6800/daemonstatus.json').json()
		# 統計當前有多少個爬蟲在運行
		running = req.get('running') + req.get('pending')
		
		# 3、判斷是否等待還是要增加爬蟲數量
		# 3.1 如果在運行的數量大于等于設置到量 則繼續等待
		if running >= limited:
			continue
		
		# 3.2 如果小于 則啟動爬蟲
		start_scrapy(info)
		# 3.3 將info從redis中刪除
		redis.delete(info)
		# 3.4 釋放鎖
		lock.release()
		break
		

@shared_task
def scrapy_control(key_uuid):

    r = redis.Redis(connection_pool=pool)
    db = MysqlDB()
    speed_limited = db.fetch_config('REPTILE_SPEED')
    speed_limited = int(speed_limited[0])

    keywords_num = MysqlDB().fetch_config('SEARCH_RANDOM')
    keywords_num = int(keywords_num[0])


    # while True:
    lock = r.lock('lock')
    with open('log/celery/info.log', 'a') as f: f.write(str(datetime.datetime.now()) + '--' + str(key_uuid) + ' 進入處理環節' +  '\n')
    try:
        # acquire默認阻塞 如果獲取不到鎖時 會一直阻塞在這個函數的while循環中
        if lock.acquire():
            with open('log/celery/info.log', 'a') as f: f.write(str(datetime.datetime.now()) + '--' + str(key_uuid) + ' 獲得鎖' +  '\n')
            # 1 從redis中獲取信息
            redis_obj = json.loads(r.get(key_uuid))
            user_id = redis_obj.get('user_id')
            contents = redis_obj.get('contents')
            
            # 2 使用while循環處理核心邏輯          
            is_hold_print = True
            while True:
                req = requests.get('http://127.0.0.1:6800/daemonstatus.json').json()
                running = req.get('running') + req.get('pending')
                # 3 如果仍然有足夠的爬蟲在運行 則hold住redis鎖，等待有空余的爬蟲位置讓出
                if running >= speed_limited:
                    if is_hold_print:
                        with open('log/celery/info.log', 'a') as f: f.write(str(datetime.datetime.now()) + '--' + str(key_uuid) + ' 爬蟲在運行，線程等待中' +  '\n')
                        is_hold_print = False
                    time.sleep(1)
                    continue
                
                # 4 有空余的爬蟲位置 則往下走
                # 4.1 處理完所有的內容后 釋放鎖
                if len(contents) == 0:
                    r.delete(key_uuid)
                    with open('log/celery/info.log', 'a') as f: f.write(str(datetime.datetime.now()) + '--' + str(key_uuid) + ' 任務已完成，從redis中刪除' +  '\n')
                    lock.release()
                    with open('log/celery/info.log', 'a') as f: f.write(str(datetime.datetime.now()) + '--' + str(key_uuid) + ' 釋放鎖' +  '\n')
                    break

                # 4.2 創建task任務
                task_uuid = str(uuid.uuid4())
                article_obj = contents.pop()
                article_id = article_obj.get('article_id')
                article = article_obj.get('content')
                try:
                    Task.objects.create(
                        task_uuid = task_uuid,
                        user_id = user_id,
                        article_id = article_id,
                        content = article
                    )
                except Exception as e:
                    with open('log/celery/error.log', 'a') as f: f.write(str(datetime.datetime.now()) + '--' + str(key_uuid) + '->' + str(task_uuid) + ' 創建Task出錯: ' + str(e) +  '\n')
                # finally:
                # 4.3 啟動爬蟲任務 即便創建task失敗也會啟動
                try:
                    task_chain(user_id, article, task_uuid, keywords_num)
                except Exception as e:
                    with open('log/celery/error.log', 'a') as f: f.write(str(datetime.datetime.now()) + '--' + str(key_uuid) + ' 啟動任務鏈失敗: ' + str(e) +  '\n')
                
                # 加入sleep 防止代碼執行速度快于爬蟲啟動速度而導致當前線程啟動額外的爬蟲
                time.sleep(5)

    except Exception as e:
        with open('log/celery/error.log', 'a') as f: f.write(str(datetime.datetime.now()) + '--' + str(key_uuid) + ' 獲得鎖之后的操作出錯: ' + str(e) +  '\n')
        lock.release()