(Perl) Async Task Chain

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

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux

use chilkat();

# All Chilkat classes can be unlocked at once at the beginning of a program
# by calling UnlockBundle.  It requires a Bundle unlock code.
$chilkatGlob = chilkat::CkGlobal->new();
$success = $chilkatGlob->UnlockBundle("Anything for 30-day trial.");
if ($success != 1) {
    print $chilkatGlob->lastErrorText() . "\r\n";
    exit;
}

$mailman = chilkat::CkMailMan->new();

# Set the POP3 server's hostname
$mailman->put_MailHost("pop.someMailServer.com");

# Set the POP3 login/password and any other requirements..
$mailman->put_PopUsername("myLogin");
$mailman->put_PopPassword("myPassword");
$mailman->put_PopSsl(1);
$mailman->put_MailPort(995);

# Connect to the POP3 server:
$success = $mailman->Pop3BeginSession();
if (!$success) {
    print $mailman->lastErrorText() . "\r\n";
    exit;
}

# Get the number of messages in the mailbox.
$numMessages = $mailman->GetMailboxCount();
if ($numMessages == 0) {
    print "No email messages in the POP3 mailbox." . "\r\n";
    exit;
}

$taskChain = chilkat::CkTaskChain->new();

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

for ($i = 1; $i <= $numMessages; $i++) {

    # task is a Task
    $task = $mailman->FetchByMsgnumAsync($i);
    if ($mailman->get_LastMethodSuccess() == 0) {
        print $mailman->lastErrorText() . "\r\n";
        exit;
    }

    # Append each task to the task chain.
    $success = $taskChain->Append($task);
    if (!$success) {
        print $taskChain->lastErrorText() . "\r\n";
        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->put_StopOnFailedTask(1);
$success = $taskChain->Run();
if (!$success) {
    print $taskChain->lastErrorText() . "\r\n";
    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->get_Finished() != 1) {

    # 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->get_StatusInt() != 7) {
    print "Task did not complete." . "\r\n";
    print "task chain status: " . $taskChain->status() . "\r\n";
    exit;
}

$email = chilkat::CkEmail->new();

$numTasks = $taskChain->get_NumTasks();
$taskIdx = 0;

while (($taskIdx < $numTasks)) {

    # task is a Task
    $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." . "\r\n";
    }
    else {
        print $email->ck_from() . "; " . $email->subject() . "\r\n";
    }

    $taskIdx = $taskIdx + 1;
}