####################################################################################################################################
# THREADGROUP MODULE
####################################################################################################################################
package BackRest::ThreadGroup;

use threads;
use strict;
use warnings FATAL => qw(all);
use Carp qw(confess);

use File::Basename;

use lib dirname($0) . '/../lib';
use BackRest::Utility;
use BackRest::Config;
use BackRest::RestoreFile;
use BackRest::BackupFile;

####################################################################################################################################
# MODULE EXPORTS
####################################################################################################################################
use Exporter qw(import);

our @EXPORT = qw(threadGroupCreate threadGroupRun threadGroupComplete threadGroupDestroy);

my @oyThread;
my @oyMessageQueue;
my @oyCommandQueue;
my @oyResultQueue;
my @byThreadRunning;

####################################################################################################################################
# threadGroupCreate
####################################################################################################################################
sub threadGroupCreate
{
    # If thread-max is not defined then this operation does not use threads
    if (!optionTest(OPTION_THREAD_MAX))
    {
        return;
    }

    # Get thread-max
    my $iThreadMax = optionGet(OPTION_THREAD_MAX);

    # Only create threads when thread-max > 1
    if ($iThreadMax > 1)
    {
        for (my $iThreadIdx = 0; $iThreadIdx < $iThreadMax; $iThreadIdx++)
        {
            push @oyCommandQueue, Thread::Queue->new();
            push @oyMessageQueue, Thread::Queue->new();
            push @oyResultQueue, Thread::Queue->new();
            push @oyThread, (threads->create(\&threadGroupThread, $iThreadIdx));
            push @byThreadRunning, false;
        }
    }
}

####################################################################################################################################
# threadGroupThread
####################################################################################################################################
sub threadGroupThread
{
    my $iThreadIdx = shift;

    # When a KILL signal is received, immediately abort
    $SIG{'KILL'} = sub {threads->exit();};

    while (my $oCommand = $oyCommandQueue[$iThreadIdx]->dequeue())
    {
        # Exit thread
        if ($$oCommand{function} eq 'exit')
        {
            &log(TRACE, 'thread terminated');
            return;
        }

        &log(TRACE, "$$oCommand{function} thread started");

        # Create a file object
        my $oFile = new BackRest::File
        (
            optionGet(OPTION_STANZA),
            optionRemoteTypeTest(BACKUP) ? optionGet(OPTION_REPO_REMOTE_PATH) : optionGet(OPTION_REPO_PATH),
            optionRemoteType(),
            optionRemote(undef, false),
            undef, undef,
            $iThreadIdx + 1
        );

        # Notify parent that init is complete
        threadMessage($oyResultQueue[$iThreadIdx], 'init');

        my $iDirection = $iThreadIdx % 2 == 0 ? 1 : -1;     # Size of files currently copied by this thread

        # Initialize the starting and current queue index based in the total number of threads in relation to this thread
        my $iQueueStartIdx = int((@{$$oCommand{param}{queue}} / $$oCommand{thread_total}) * $iThreadIdx);
        my $iQueueIdx = $iQueueStartIdx;

        # Keep track of progress
        my $lSizeCurrent = 0;   # Running total of bytes copied

        # Loop through all the queues (exit when the original queue is reached)
        do
        {
            &log(TRACE, "reading queue ${iQueueIdx}, start queue ${iQueueStartIdx}");

            while (my $oMessage = ${$$oCommand{param}{queue}}[$iQueueIdx]->dequeue_nb())
            {
                if ($$oCommand{function} eq 'restore')
                {
                    restoreFile($oMessage, $$oCommand{param}{copy_time_begin}, $$oCommand{param}{delta}, $$oCommand{param}{force},
                                $$oCommand{param}{backup_path}, $$oCommand{param}{source_compression},
                                $$oCommand{param}{current_user}, $$oCommand{param}{current_group}, $oFile, 0, 0);
                }
                elsif ($$oCommand{function} eq 'backup')
                {
                    # Result hash that can be passed back to the master process
                    my $oResult = {};

                    # Backup the file
                    ($$oResult{copied}, $lSizeCurrent, $$oResult{size}, $$oResult{checksum}) =
                        backupFile($oFile, $$oMessage{db_file}, $$oMessage{backup_file}, $$oCommand{param}{compress},
                                   $$oMessage{checksum}, $$oMessage{modification_time},
                                   $$oMessage{size}, 0, 0);

                    # Send a message to update the manifest
                    $$oResult{file_section} = $$oMessage{file_section};
                    $$oResult{file} = $$oMessage{file};

                    $$oCommand{param}{result_queue}->enqueue($oResult);
                }
                else
                {
                    confess &log(ERROR, "unknown command");
                }
            }

            # Even numbered threads move up when they have finished a queue, odd numbered threads move down
            $iQueueIdx += $iDirection;

            # Reset the queue index when it goes over or under the number of queues
            if ($iQueueIdx < 0)
            {
                $iQueueIdx = @{$$oCommand{param}{queue}} - 1;
            }
            elsif ($iQueueIdx >= @{$$oCommand{param}{queue}})
            {
                $iQueueIdx = 0;
            }
        }
        while ($iQueueIdx != $iQueueStartIdx);

        # Notify parent of shutdown
        threadMessage($oyResultQueue[$iThreadIdx], 'shutdown');
        threadMessageExpect($oyMessageQueue[$iThreadIdx], 'continue');

        # Destroy the file object
        undef($oFile);

        # Notify the parent process of thread exit
        $oyResultQueue[$iThreadIdx]->enqueue('complete');

        &log(TRACE, "$$oCommand{function} thread exiting");
    }
}

####################################################################################################################################
# threadMessage
####################################################################################################################################
sub threadMessage
{
    my $oQueue = shift;
    my $strMessage = shift;
    my $iThreadIdx = shift;

    # Send the message
    $oQueue->enqueue($strMessage);

    # Define calling context
    &log(TRACE, "sent message '${strMessage}' to " . (defined($iThreadIdx) ? 'thread ' . ($iThreadIdx + 1) : 'controller'));
}

####################################################################################################################################
# threadMessageExpect
####################################################################################################################################
sub threadMessageExpect
{
    my $oQueue = shift;
    my $strExpected = shift;
    my $iThreadIdx = shift;
    my $bNoBlock = shift;

    # Set timeout based on the message type
    my $iTimeout = defined($bNoBlock) ? undef: 600;

    # Define calling context
    my $strContext = defined($iThreadIdx) ? 'thread ' . ($iThreadIdx + 1) : 'controller';

    # Wait for the message
    my $strMessage;

    if (defined($iTimeout))
    {
        &log(TRACE, "waiting for '${strExpected}' message from ${strContext}");
        $strMessage = $oQueue->dequeue_timed($iTimeout);
    }
    else
    {
        $strMessage = $oQueue->dequeue_nb();

        return false if !defined($strMessage);
    }

    # Throw an exeception when the message was not received
    if (!defined($strMessage) || $strMessage ne $strExpected)
    {
        confess &log(ASSERT, "expected message '$strExpected' from ${strContext} but " .
                             (defined($strMessage) ? "got '$strMessage'" : "timed out after ${iTimeout} second(s)"));
    }

    &log(TRACE, "got '${strExpected}' message from ${strContext}");

    return true;
}

####################################################################################################################################
# threadGroupRun
####################################################################################################################################
sub threadGroupRun
{
    my $iThreadIdx = shift;
    my $strFunction = shift;
    my $oParam = shift;

    my %oCommand;
    $oCommand{function} = $strFunction;
    $oCommand{thread_total} = @oyThread;
    $oCommand{param} = $oParam;

    $oyCommandQueue[$iThreadIdx]->enqueue(\%oCommand);

    threadMessageExpect($oyResultQueue[$iThreadIdx], 'init', $iThreadIdx);
    $byThreadRunning[$iThreadIdx] = true;
}

####################################################################################################################################
# threadGroupComplete
#
# Wait for threads to complete.
####################################################################################################################################
sub threadGroupComplete
{
    my $self = shift;
    my $iTimeout = shift;
    my $bConfessOnError = shift;

    # Set defaults
    $bConfessOnError = defined($bConfessOnError) ? $bConfessOnError : true;

    # Wait for all threads to complete and handle errors
    my $iThreadComplete = 0;
    my $lTimeBegin = time();
    my $strFirstError;
    my $iFirstErrorThreadIdx;

    &log(DEBUG, "waiting for " . @oyThread . " threads to complete");

    # Rejoin the threads
    # while ($iThreadComplete < @oyThread)
    # {
        hsleep(.1);

        # If a timeout has been defined, make sure we have not been running longer than that
        if (defined($iTimeout))
        {
            if (time() - $lTimeBegin >= $iTimeout)
            {
                confess &log(ERROR, "threads have been running more than ${iTimeout} seconds, exiting...");
            }
        }

        for (my $iThreadIdx = 0; $iThreadIdx < @oyThread; $iThreadIdx++)
        {
            if ($byThreadRunning[$iThreadIdx])
            {
                my $oError = $oyThread[$iThreadIdx]->error();

                if (defined($oError))
                {
                    my $strError;

                    if ($oError->isa('BackRest::Exception'))
                    {
                        $strError = $oError->message();
                    }
                    else
                    {
                        $strError = $oError;
                        &log(ERROR, "thread " . ($iThreadIdx) . ": ${strError}");
                    }

                    if (!defined($strFirstError))
                    {
                        $strFirstError = $strError;
                        $iFirstErrorThreadIdx = $iThreadIdx;
                    }

                    $byThreadRunning[$iThreadIdx] = false;
                    $iThreadComplete++;
                }
                elsif (threadMessageExpect($oyResultQueue[$iThreadIdx], 'shutdown', $iThreadIdx, true))
                {
                    threadMessage($oyMessageQueue[$iThreadIdx], 'continue', $iThreadIdx);
                    threadMessageExpect($oyResultQueue[$iThreadIdx], 'complete', $iThreadIdx);
                    $byThreadRunning[$iThreadIdx] = false;
                    $iThreadComplete++;
                }
            }
            else
            {
                $iThreadComplete++;
            }
        }
    # }

    # If there were errors then confess them
    if (defined($strFirstError) && $bConfessOnError)
    {
        confess &log(ERROR, 'error in thread' . ($iFirstErrorThreadIdx + 1) . ": $strFirstError");
    }

    # Return true if all threads have completed
    if ($iThreadComplete == @oyThread)
    {
        &log(DEBUG, 'all threads exited');
        return true;
    }

    return false;
}

####################################################################################################################################
# threadGroupDestroy
####################################################################################################################################
sub threadGroupDestroy
{
    my $self = shift;

    &log(TRACE, "waiting for " . @oyThread . " threads to be destroyed");

    for (my $iThreadIdx = 0; $iThreadIdx < @oyThread; $iThreadIdx++)
    {
        my %oCommand;
        $oCommand{function} = 'exit';

        $oyCommandQueue[$iThreadIdx]->enqueue(\%oCommand);
        hsleep(.1);

        if ($oyThread[$iThreadIdx]->is_running())
        {
            $oyThread[$iThreadIdx]->kill('KILL')->join();
            &log(TRACE, "thread ${iThreadIdx} killed");
        }
        elsif ($oyThread[$iThreadIdx]->is_joinable())
        {
            $oyThread[$iThreadIdx]->join();
            &log(TRACE, "thread ${iThreadIdx} joined");
        }

        undef($oyThread[$iThreadIdx]);
    }

    &log(TRACE, @oyThread . " threads destroyed");

    return(@oyThread);
}

1;