Chilkat2-Python

Async Task Chain

See more Async Examples

Demonstrates how to combine a sequence of asynchronous tasks into a single task chain to be run in a background thread. Chilkat2-Python

import sys
import chilkat2

success = False

# This example assumes the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

success = False

mailman = chilkat2.MailMan()

# Set the POP3 server's hostname
mailman.MailHost = "pop.example.com"

# Set the POP3 login/password and any other requirements..
mailman.PopUsername = "myLogin"
mailman.PopPassword = "myPassword"
mailman.PopSsl = True
mailman.MailPort = 995

# Connect to the POP3 server:
success = mailman.Pop3BeginSession()
if (not success):
    print(mailman.LastErrorText)
    sys.exit()

# Get the number of messages in the mailbox.
numMessages = mailman.GetMailboxCount()
if (numMessages == 0):
    print("No email messages in the POP3 mailbox.")
    sys.exit()

taskChain = chilkat2.TaskChain()

# Create async task objects to fetch each email message
# by its sequence number

for i in range(1,(numMessages)-1):

    # task is a CkTask
    task = mailman.FetchByMsgnumAsync(i)
    if (mailman.LastMethodSuccess == False):
        print(mailman.LastErrorText)
        sys.exit()

    # Append each task to the task chain.
    success = taskChain.Append(task)
    if (not success):
        print(taskChain.LastErrorText)
        sys.exit()

# At this point, no tasks have actually started running.
# All we've done so far is to create tasks for the work that will be done
# when the task chain is run.

# Start the task chain running in a background thread.
# Each task is run one after the other (on the same background thread) until all tasks have completed.
# The task chain will stop at the first task that fails.
taskChain.StopOnFailedTask = True
success = taskChain.Run()
if (not success):
    print(taskChain.LastErrorText)
    sys.exit()

# The application is now free to do anything else
# while the emails are being downloaded

# For this example, we'll simply sleep and periodically
# check to see if the taskchain if finished. 
while taskChain.Finished != True :

    # Sleep 100 ms.
    taskChain.SleepMs(100)

# A finished task chain could be one that was canceled, aborted, or truly finished.  

# If the task chain "completed", then it ran to completion.  A "completed" task will
# have a StatusInt equal to 7.   If the task finished, but was not completed, then it must've
# been aborted or canceled:
if (taskChain.StatusInt != 7):
    print("Task did not complete.")
    print("task chain status: " + taskChain.Status)
    sys.exit()

email = chilkat2.Email()

numTasks = taskChain.NumTasks
taskIdx = 0

while (taskIdx < numTasks) :

    # task is a CkTask
    task = taskChain.GetTask(taskIdx)

    # Load the email object with email downloaded by this task.
    success = email.LoadTaskResult(task)
    if (not success):
        print("Failed to load email object for task.")
    else:
        print(email.From + "; " + email.Subject)

    taskIdx = taskIdx + 1