Ruby

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. Ruby

require 'chilkat'

success = false

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

success = false

mailman = Chilkat::CkMailMan.new()

# Set the POP3 server's hostname
mailman.put_MailHost("pop.example.com")

# Set the POP3 login/password and any other requirements..
mailman.put_PopUsername("myLogin")
mailman.put_PopPassword("myPassword")
mailman.put_PopSsl(true)
mailman.put_MailPort(995)

# Connect to the POP3 server:
success = mailman.Pop3BeginSession()
if (!success)
    print mailman.lastErrorText() + "\n";
    exit
end

# Get the number of messages in the mailbox.
numMessages = mailman.GetMailboxCount()
if (numMessages == 0)
    print "No email messages in the POP3 mailbox." + "\n";
    exit
end

taskChain = Chilkat::CkTaskChain.new()

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

for i in 1 .. numMessages

    # task is a CkTask
    task = mailman.FetchByMsgnumAsync(i)
    if (mailman.get_LastMethodSuccess() == false)
        print mailman.lastErrorText() + "\n";
        exit
    end

    # Append each task to the task chain.
    success = taskChain.Append(task)
    if (!success)
        print taskChain.lastErrorText() + "\n";
        exit
    end

end

# 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.put_StopOnFailedTask(true)
success = taskChain.Run()
if (!success)
    print taskChain.lastErrorText() + "\n";
    exit
end

# 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.get_Finished() != true

    # Sleep 100 ms.
    taskChain.SleepMs(100)

end

# 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.get_StatusInt() != 7)
    print "Task did not complete." + "\n";
    print "task chain status: " + taskChain.status() + "\n";
    exit
end

email = Chilkat::CkEmail.new()

numTasks = taskChain.get_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 (!success)
        print "Failed to load email object for task." + "\n";
    else
        print email.ck_from() + "; " + email.subject() + "\n";
    end

    taskIdx = taskIdx + 1
end