Question

我试图让mqtt客户端收到它订阅的主题中的所有消息，但是每次我使用另一个客户端发送消息时它只接收第一个消息。问题是客户端应该使用qos 2处理10条消息，而只处理第一条消息。消息以几毫秒的时间间隔同时发送。我不是经常发送消息。我每分钟发送10条消息。两个客户都是持久的。我确定该消息离开了发布者，因为无论何时发送消息，我都会打印它的有效负载。我使用qos 2因为收到的邮件然后保存到数据库中，我不想要重复。我使用的经纪人是activemq。所以问题是为什么会发生这种情况？

from sqlalchemy.ext.automap import automap_base
from sqlalchemy.orm import Session
from sqlalchemy import create_engine
from sqlalchemy import update
from sqlalchemy.ext.automap import generate_relationship
import sqlalchemy
import paho.mqtt.client as mqtt
import time  
#Function that define what to do on client conenction
def on_connect(client, userdata, rc):
    #Subscribe to all specified topics
    mqttc.subscribe(topic='/+/mysignals/sensors/+/')
def on_message(client,userdata,message):
    #Get the mysignals member id from the topic
    topic_split = message.topic.split('/')
    member_id = topic_split[1]
    session = Session(engine)
    sensor_id = topic_split[4]
    patient = session.query(Patient).filter(Patient.mysignalsid==member_id).first()
    if message.payload == None:
        payload = 0
    else:
        payload = message.payload
    if patient:
        current_time = time.time()
        if patient.id in pending.keys() and (current_time - pending[patient.id]['time_created']) <= 55:
            pending[patient.id]['record'].__dict__[sensor_id] = payload
            print time.time()
        else:
            pending.pop(patient.id,None)
            patientdata = PatientData()
            patientdata.__dict__[sensor_id] = payload
            print patientdata.__dict__[sensor_id]
            print payload
            print patientdata.temp
            patient.patientdata_collection.append(patientdata)
            session.add(patientdata)
            print time.time()
            pending.update({patient.id:{
                                    'time_created':time.time(),
                                    'record':patientdata,
                                    }})
        session.flush()
        session.commit()
        print('Wrote to database.')

pending = {}
Base = automap_base()
engine = create_engine('mysql+mysqlconnector://user:pass@localhost/db')
# reflect the tables
Base.prepare(engine, reflect=True)
Patient = Base.classes.patient
PatientData = Base.classes.patientdata
session = Session(engine)
#Create a mqtt client object
mqttc = mqtt.Client(client_id='database_logger',clean_session=False)
#Set mqtt client callbacks
mqttc.on_connect = on_connect
mqttc.on_message = on_message
#Set mqtt broker username and password
mqttc.username_pw_set('blah','blahblah')
#Connect to the mqtt broker with the specified hostname/ip adress
mqttc.connect('127.0.0.1')
mqttc.loop_forever()

输出继电器：

98
98
None
1500576377.3
Wrote to database.
1500576377.43
Wrote to database.

输出应为：

98
98
None
1500576377.3
Wrote to database.
25.4
25.4
25.4
1500576377.43
Wrote to database.

Answer 1

最终这不是mqtt客户端的问题。代码错误，第二条消息没有写入数据库。

为了让它工作，我不得不更换以下行：

pending[patient.id]['record'].__dict__[sensor_id] = payload

这一个：

setattr(pending[patient.id]['record'],sensor_id,payload)

同时删除该行：

session = Session(engine)

在on_message函数之外。

我还添加了一行：

session.expunge_all()

线下方：

session.commit()

每次在数据库中完成事务时清理会话。

Mqtt客户端无法同时处理多条消息

1 个答案: