MQTT和时间延迟

Question

我有一个 python 脚本，我正在尝试使用它来处理 paho mqtt 和时间延迟。我研究了类似的问题，这些问题讨论了 paho mqtt，例如Controlling Program with MQTT and Python。我的python脚本如下：这是我的脚本： import paho.mqtt.client as mqttClient    import time    import subprocess    import os            global lastprocessed, Connected    lastprocessed = None    Connected = False   #global variable for the state of the connection        def on_connect(client, userdata, flags, rc):        if rc == 0:            print("Connected to broker")            global Connected            Connected = True                #Signal connection        else:            print("Connection failed")            def on_message(client, userdata, message):        global lastprocessed        if message.payload.decode() == "hello":            lastprocessed = time.time()            if lastprocessed and time.time() - lastprocessed < 20:            print("good")broker_address= "192.168.1.111"  #Broker addressport = 1883                         #Broker portuser = "abcde"                    #Connection usernamepassword = "12345"            #Connection passwordclient = mqttClient.Client("Python")               #create new instanceclient.username_pw_set(user, password=password)    #set username and passwordclient.on_connect= on_connect                      #attach function to callbackclient.on_message= on_message                      #attach function to callbackclient.connect(broker_address,port,60) #connectclient.subscribe("home/OpenMQTTGateway/433toMQTT") #subscribeclient.loop_forever() #then keep listening forever我上面的代码发生的事情是，只要在有效负载中收到“hello”，它就会打印“good”，但如果在有效负载中收到任何其他内容，包括“hello”，它会继续打印“good”。它没有考虑 20 秒的时间。我不确定为什么？我想要实现的目标如下：当开始执行 python 脚本时，脚本应该打印“bad”。这应该停止，直到在有效负载中收到“hello”。一旦收到“hello”，“good”应该打印 20 秒，在这 20 秒内，主题中收到的任何其他消息都应该被忽略，包括“hello”。20 秒后，脚本应该继续打印“坏”，但只打印一次，循环继续。

Answer 1

我使用loop_start()andloop_stop()而不是loop_forever()然后使用 between start，stop我可以创建自己的循环来检查消息和打印文本。

我使用变量state来控制代码是在第一个hello( state = "start") 之前还是它得到hello，现在它必须检查时间并重复文本“好” ( state = "hello") 或者它有 20 秒之后hello并且它没有打印任何内容 (state = "other")

在内部on_message，我只hello在收到消息时才将状态更改为hello，而旧状态则不同hello。

import paho.mqtt.client as mqttClient

import time

# --- functions ---

def on_connect(client, userdata, flags, rc):

    #global state

    global connected

    if rc == 0:

        print("Connected to broker")

        connected = True                

    else:

        print("Connection failed")

def on_message(client, userdata, message):

    global state

    global last_processed

    

    if message.payload.decode() == "hello":

        if state != 'hello':

            state = 'hello'

            last_processed = time.time()

    # OR

    

    #if state != 'hello':

    #    if message.payload.decode() == "hello":

    #        state = 'hello'

    #        last_processed = time.time()

# --- main ---

broker_address = "192.168.1.111"  # broker address

port = 1883                       # broker port

user = "abcde"                    # connection username

password = "12345"                # connection password

# ---

client = mqttClient.Client("Python")               # create new instance

client.username_pw_set(user, password=password)    # set username and password

client.on_connect= on_connect                      # attach function to callback

client.on_message= on_message                      # attach function to callback

client.connect(broker_address, port, 60)           # connect

client.subscribe("home/OpenMQTTGateway/433toMQTT") # subscribe

# --- main loop ---

last_processed = None

connected = False      # signal connection

state = 'start' # 'start', 'hello', 'other', 'not connected'   

# ---

client.loop_start()

try:

    while True:

        if not connected:

            print('not connected')

            

        if state == 'start':

            print('bad')

            

        if state == 'hello':

            if last_processed and time.time() - last_processed < 20:

                print("good", time.time() - last_processed, end='\r') # '\r` to write it in the same line.

            else:

                print('bad')

                state = 'other'

                last_processed = None

        

        if state == 'other':

            pass

    

        time.sleep(1.0) # to slow down example

        

except KeyboardInterrupt:

    print('KeyboardInterrupt')

    

client.loop_stop()

编辑：

如果您只需要bad一次hello，那么您可以bad在循环之前先打印，然后hello在收到消息时打印，然后time.sleep(20)在打印bad和更改状态之前打印。

import paho.mqtt.client as mqttClient

import time

# --- functions ---

def on_connect(client, userdata, flags, rc):

    #global state

    global connected

    if rc == 0:

        print("Connected to broker")

        connected = True                

    else:

        print("Connection failed")

def on_message(client, userdata, message):

    global state

    message = message.payload.decode()

    

    if state != 'hello':

        if message == 'hello':

            state = 'hello'

            print('good') # once when start `hello`

        else:

            print('msg:', message)        

# --- main ---

broker_address = "192.168.1.111"  # broker address

port = 1883                       # broker port

user = "abcde"                    # connection username

password = "12345"                # connection password

# ---

client = mqttClient.Client("Python")               # create new instance

client.username_pw_set(user, password=password)    # set username and password

client.on_connect= on_connect                      # attach function to callback

client.on_message= on_message                      # attach function to callback

client.connect(broker_address, port, 60)           # connect

client.subscribe("home/OpenMQTTGateway/433toMQTT") # subscribe

# --- main loop ---

connected = False      # signal connection

state = 'other' # 'hello'

# ---

client.loop_start()

print('bad') # once at start

try:

    while True:

        

        if state == 'hello':

            time.sleep(20)

            print('bad')  # once when end `hello`

            state = 'other'

    

        time.sleep(1.0) # to slow down example

        

except KeyboardInterrupt:

    print('KeyboardInterrupt')

    

client.loop_stop()

使用threading.Timerinstead of time.sleep()because sleep()blocks loop 会很有用，如果你想做更多的事情，它就没那么有用了。

import paho.mqtt.client as mqttClient

import threading

# --- functions ---

def on_connect(client, userdata, flags, rc):

    #global state

    global connected

    if rc == 0:

        print("Connected to broker")

        connected = True                

    else:

        print("Connection failed")

def on_message(client, userdata, message):

    global state

    message = message.payload.decode()

    

    if state != 'hello':

        if message == 'hello':

            state = 'hello'

            print('good') # once when start `hello`

            threading.Timer(20, end_hello).start()

        else:

            print('msg:', message)

        

def end_hello():

    global state

    

    print('bad')  # once when end `hello`

    state = 'other'

# --- main ---

broker_address = "192.168.1.111"  # broker address

port = 1883                       # broker port

user = "abcde"                    # connection username

password = "12345"                # connection password

# ---

client = mqttClient.Client("Python")               # create new instance

client.username_pw_set(user, password=password)    # set username and password

client.on_connect= on_connect                      # attach function to callback

client.on_message= on_message                      # attach function to callback

client.connect(broker_address, port, 60)           # connect

client.subscribe("home/OpenMQTTGateway/433toMQTT") # subscribe

# --- main loop ---

connected = False      # signal connection

state = 'other' # 'hello'

# ---

print('bad') # once at start

client.loop_forever()

最终你仍然可以检查循环时间

import paho.mqtt.client as mqttClient

import time

# --- functions ---

def on_connect(client, userdata, flags, rc):

    #global state

    global connected

    if rc == 0:

        print("Connected to broker")

        connected = True                

    else:

        print("Connection failed")

def on_message(client, userdata, message):

    global state

    global last_processed

    

    message = message.payload.decode()

    

    if state != 'hello':

        if message == 'hello':

            state = 'hello'

            last_processed = time.time()

            print('good') # once when start `hello`

        else:

            print('msg:', message)        

# --- main ---

broker_address = "192.168.1.111"  # broker address

port = 1883                       # broker port

user = "abcde"                    # connection username

password = "12345"                # connection password

# ---

client = mqttClient.Client("Python")               # create new instance

client.username_pw_set(user, password=password)    # set username and password

client.on_connect= on_connect                      # attach function to callback

client.on_message= on_message                      # attach function to callback

client.connect(broker_address, port, 60)           # connect

client.subscribe("home/OpenMQTTGateway/433toMQTT") # subscribe

# --- main loop ---

last_processed = None

connected = False      # signal connection

state = 'other' # 'hello'

# ---

client.loop_start()

print('bad') # once at start

try:

    while True:

        

        if state == 'hello':

            if time.time() >= last_processed + 20:

                print('bad')  # once when end `hello`

                state = 'other'

    

        time.sleep(1.0) # to slow down example

        

except KeyboardInterrupt:

    print('KeyboardInterrupt')

    

client.loop_stop()