Revision history for Perl extension Parallel::Depend (most recent first).

4.09 Tue Jun 30 12:14:45 EDT 2009

• POD. It ain't perfect but does include the "alias % global" and "ad_hoc" settings for embedded schedules.
• share_queue without prepared queue is non-fatal, returns empty list.
• Force and restart used to be exclusive, with restart failing if any jobs looked like they were currently running. In the interest of offering more rope for your gun [bullets for your gallows?], force+restart now treats that any incomplete runfiles as non-running, failed jobs and restarts them.
• $SIG{ INT } stores an abort message -- makes it simpler to use ^C to abort a queue and then restart it.
• In order to handle situations where the jobs fork their own cleanup tasks on exit (e.g., gzip output), the reaping cycle loops via next if the current job is not in the fork table. This will reap however many orphans it can in one pass without bothering to check with runnable.

4.08 Sun Jun 28 18:52:54 EDT 2009

• Groups have to do some housekeeping on their way out. Simplest way to ensure it gets done is add an ad_hoc attribute to each group job. Since the group's job runs at the end, running it without forking allows any necessary cleanups to happen (see next item also).

  This has an advantage for long-lived schedules since purging the extra data keeps the queue at a reasonable size if multiple sets of ad-hoc jobs are added over time.

• ad_hoc groups are a convienent way for factory items to insert schedule content.

  Catch: The object that dispatched ad_hoc may not be the one used to unalias the job within execute.

  Fix: the ad_hoc method adds the current object into the attributes for its hidden group. Within unalias, the ad_hoc_mgr attribute is used if it exists to resolve method calls.

  The object will stay alive for the group execution due to being stored in the group's attributes, which are purged on the way out of the group (see previous item).

  Result is that a main handler can use something like:

my $child = $other_class->new;

$mgr->share_queue( $child );

...

$child->ad_hoc( @stuff );

and know that $child will be used to
dispatch the jobs added via ad_hoc
and also that $child will be destroyed after all of its ad-hoc jobs have been completed.

• Added "purge_group" to purge the attributes and aliases for the group job itself and the group-specific tables for jobs that ran inside of the group.

  This is called from the group method, call this via SUPER or NEXT if the method is overridden. This is where the ad hoc manager object is dropped, so failing to cause this will leave any number of otherwise-short-lived objects floating around in the attributes until the schedule completes.

• Add "has_queue" with alias "was_prepared" to check if the manager object has called prepare successfully -- which will leave it with a queue.

4.07 Mon Jun 8 19:43:45 EDT 2009

• Fix typo "INT_" in signal name.
• Two things simplify generation of template schedules: default alias and 'ad_hoc' attribute for the alias.
• Add single-level attribute for groups to use the group name as an alias for all jobs in the group.

  This is for staged operations where a set of modules handle, say, the processing of a group of files in one dataset. They all have the same methods for each stage:

    serialize   < Nodes     = pass1 >
    serialize   < Names     = pass1 >

serialize < Division = pass1 >
serialize < Delnodes = pass1 >
serialize < Merged = pass1 >

    serialize   < Nodes     :       >
    serialize   < Names     :       >
    serialize   < Division  :       >
    serialize   < Delnodes  :       >
    serialize   < Merged    :       >

becomes just:

    serialize   < alias     % pass1 >
    serialize   < Nodes     :       >
    serialize   < Names     :       >
    serialize   < Division  :       >
    serialize   < Delnodes  :       >
    serialize   < Merged    :       >

The alias is not inherited to avoid accidentally polluting ad_hoc or nested groups. This defines a default alias, allowing for:

    serialize   < alias     % pass1 >
    serialize   < Nodes     = foo   > # explicit alias is foo
    serialize   < Nodes     :       > # default alias is pass1
    serialize   < Names     :       > 
    serialize   < Division  :       >
    serialize   < Delnodes  :       >
    serialize   < Merged    :       >

• The 'ad_hoc' attribute can be assigned to an alias. This simplifies schedules like:

    serialize   < alias     % pass1 >
    serialize   < Nodes     ~ ad_hoc> 
    serialize   < Names     ~ ad_hoc> 

serialize < Division ~ ad_hoc>
serialize < Delnodes ~ ad_hoc>
serialize < Merged ~ ad_hoc>

    serialize   < Nodes     :       > # default alias is pass1
    serialize   < Names     :       > 
    serialize   < Division  :       >
    serialize   < Delnodes  :       >
    serialize   < Merged    :       >

to just:

    serialize   < alias     % pass1 >
    serialize   < pass1     ~ ad_hoc>
    serialize   < Nodes     :       >
    serialize   < Names     :       > 
    serialize   < Division  :       >
    serialize   < Delnodes  :       >
    serialize   < Merged    :       >

Which leaves each of the jobs (Nodes, Names, etc) handed of as ad_hoc jobs via the managers 'pass1' as $mgr->pass1( $job ).

• Pushed the alias resolver into P::D::Queue, unalias returns the name and sub, but $que->resolve_alias( $job ) will return just the alias. This is used in merge_attrib to get alias attributes.
• merge_attrib uses global, alias, and job attributes. this allows for "alias ~ foo" in the schedules.

4.06 Thu Jun 4 16:14:16 EDT 2009

• Added ./Profile programs to MANIFEST. These are stripped down schedules with empty jobs that are useful for profiling the library. For example:

make && perl -Mblib -d:Profile Profile/many-jobs-fork; less prof.out;

Note that these require Devel::Profile, which is not in the dependency tree.

• Add boilerplate to ad_hoc jobs.
• Pushed the expensive tests into t/expensive. They still require EXPENSIVE_TESTS true but this avoids the extraneous junk.
• Add a few more ad_hoc tests [which seem to work].
• Pushed namespace, group name generation and splitting of job_ids into queue in order to keep the constants used with them ($nspace_sep, $job_id_sep) private.

4.05 Fri May 29 12:36:43 EDT 2009

• Split out que contents lookups into separate module. Doesn't add any new functionality but helps keep the code cleaner and should simplify overloading storage of the contents via DBM::Deep or DBIx modules.
• The queues "attrib" and "alias" values are localized more simply using $que->alias and $que->attrib.
• Saner names for a few of the internal methods: job_attrib became merge_attrib.
• Removed unused 'group' from the queue structure.
• Test cleanups, in particular t/05* uses an autoload to make the nesting aliases more obvious -- and test the autoload feature.
• Job-specific attributes for anything pending are cached to save unnecessary calls to $que->merge_attrib (profiling showed it to be one of the big hits).
• Added a bit of boilerplate to the signal handlers to avoid a logic race with a signal arriving before the defaults had been restored in the child processes.
• The runnable test became to expensive for large jobs. The simplest speedup was to replace empty hashes with false values when the hashes are first found to be empty. This changed the code from grep { ! %{ $h->{$k} } } to grep { ! $h->{$k} } and seemed to help.
• There are also a few performance tweaks in precheck, which only checks the logdir, rundir once (via gendir) and uses them as-is for the individual file checks.
• Documentation is [surprise] lagging. It isn't hopeless but definitions of the guts are mostly useless at this point -- though the interfaces work as shown. Adding proper doc's for ad_hoc schedules is next, then the guts.

4.04 Thu May 21 15:57:40 EDT 2009

• Added '~' to set job-specific attributes. This avoids having to set jobs calling ad_hoc in their own group in order to avoid forking them. The nofork setting is requird to make the schedule changes visible to the execution handler (otherwise they are installed into a forked proc's copy of the queue and discarded).

  The new syntax also allows setting verbose, etc, for single jobs. The default for most items is true (1), separate the attribute with whitespace to store another value:

  peaches : cream

  peaches ~ ad_hoc # peaches is not forked. peaches ~ verbose # verbose % 1 for peaches. cream ~ verbose 2 # verbose %2 for cream.

  peaches = frobnicate # ad_hoc doesn't affect alias

• Begin [long overdue] POD updates.
• Isolate all attribute sanity checks in validate_attrs. Makes it easier to overload.
• Clean up t/13*t for checking ad_hoc handling.

4.03 Tue May 19 14:15:18 EDT 2009

• $mgr->ad_hoc will now add jobs into a running schedule. This is intended for cases where one job will, say, examine the filesystem and generate jobs for each file it finds. Because it is not possible [yet] to re-validated a running queue, it is up to the caller to avoid deadlocks in schedules with ad-hoc components. See t/13*t for examples of generating and using the ad_hoc call.
• Add "prefork" and "postfork" calls. The former is made in the parent process, the latter in the child. These are mainly for cleaning up things like DBI handles to a known state. If the manager object can( thing ) then it will be called.

4.02 May 11 2009

• Remove Devel::Size from the main tests; add new ones that aren't part of the normal test cycle for anyone else who cares. That removes Devel::Size from the dependency list.

4.00 Mon Mar 23 11:01:50 EDT 2009

• use v5.10;
• Adding nested groups required a full re-write of the guts. The groups are parsed completely, including nesting, during prepare. This means that there are no more delayed-effects from parsing groups. This now allows the groups to be handled without a separate fork, so the maxjobs applies across multiple groups running at the same time.

  Keeping the group items in on place required adding a namespace for jobs within groups -- the older method hid the groups from one another via forks. This leaves the keys for job, alias, attribute, etc, entries looking like $que->{ $namespace, $job }. The default (global) namespace is an empty string, successive levels of groups are appended to their parent namespace to get their own.

  The namespace and name can be taken from:

      my $i         = rindex $fullname, $Parallel::Depend::job_id_sep;
      my $namespace = substr $fullname, 0, $i;
      my $name      = substr $fullname, $i+2;

the separator variable is a read-only copy of $; (which gets messy in syntax use).

Namespaces are also used to generate log and runfiles, with the $; replaced with '-'.

• Same basic interface, saner logging, nested groups. Also the parser and pieces of the execution engine were broken out into smaller chunks for easier viewing.

  The main external differences are that the run files include a timestamp and the log files use a group-nested namespace for everything. Logging also includes the namespace (i.e., nested group) for all jobs to uniquely identify them (i.e. no more collisions between job names in separate groups). Unneeded subs were also stripped from P::D::Util (see 00* tests for quick list of public methods).

  Dependencies between groups are also a bit more reliable with group namespaces for the jobs.

  More, smaller tests give a better illustration of how to use the code.

  This also leaves the queue structure suitable for persistence management via DBM::Deep, which would allow simpler restarts without depending on the local filesystem for bookkeeping.

3.07 Wed Jan 28 16:15:58 EST 2009

• Update META.yaml, minor cleanups.
• use fileparse to strip directory, suffix from job before generating pidfile. this allows rooted paths to be used as job specifiers.
• POD

3.06 Sun Jan 25 19:48:58 EST 2009

• Put autodie into Makefile.PL

3.05 Thu Jan 22 18:49:29 EST 2009

• Push the prefix into attributes to simplify handling during group/subqueue. This puts all of the inherited items into @inherit.
• Add tests for existing .pid, .out, .err files in t/0[12]*t.
• Update POD for changes since Schedule::Depend was retired in favor of "Parallel::Depend".
• Remove 'executed' flag: it caused too much confusion when used with subque and groups. The precheck method deals with this gracefully enough at this point.

3.04 Mon Jan 19 16:44:06 EST 2009

• Minor code & doc cleanups.
• Handle prefixes a bit more gracefully by defaulting the initial prefix to basename $0.

3.03 Sat Dec 27 15:00:13 EST 2008

• Regex Typo.

3.02 Wed Dec 24 13:05:32 EST 2008

• Clean up group handling.
• Clean up whitespace handling.
• Simplify loops for building que elements prior to breaking them out into separate sub's.
• Add autodie to requisites.

3.01 Tue Dec 23 12:59:47 EST 2008

• Modify regex to handle splitting up standalone jobs ('foo:') to handle whitespace variances.

3.0 Mon Dec 22 18:05:42 EST 2008

• Reworked interface, parsing. Interface now uses inside-out class for the que data, allows using any generic object as the manager.
• Parsing input schedule is faster, especially for large schedule lists.

2.5 Fri Apr 29 19:48:08 EDT 2005

• Added S::D::U::handle_que_args

Allows que methods to use:

my ( $que, $config ) = &handle_args;

or

my ( $config ) = &handle_args;

and yanks $que off of the stack. It also sets $DB::single = 1 if $que->debug (i.e., automatic breakpoint in debug mode) and logs the caller, arguments.

This replaces the top few lines of nearly every que method.

2.4 Tue Apr 26 16:54:56 EDT 2005

• Replaced use of internal "debug" que attribute with "validate" to avoid conflict with "runsched" use of the attribute (debugging a queue). This allows for:

$que->subque( %blah )->validate->execute;

when executing via runsched in debug mode.

2.3 Sat Jan 15 10:17:11 EST 2005

• Added "splat" to Utilities. This writes out larger items as tab-separated-values files, which saves overhead of Dumper. Update slurp to eval then split on newlines and tabs (i.e., handle splat output).

2.2 Mon Jan 10 08:20:47 UTC 2005

• Added sanity check for missing classes after use base of the user's use_base list. This spots missing classes (i.e, ones that didn't compile) before their sub's fail up as "shellexec" calls at runtime.

2.1 Sun Dec 26 06:34:50 EST 2004

• Fixed a typo in Utilities, replaced {basename} with {basenames} in config check for localpath.

2.00 Sun Dec 26 06:34:50 EST 2004

• Added doc's for Execute, Utilities, and Config modules. Updated comments in all of the modules.

1.00 Fri Apr 9 01:28:58 CDT 2004

• Added Parallel::Depend::Execute, S::D::Config,
• Added Parallel::Depend::Execute, S::D::Config, S::D::Utilities to simplify generating #! code and methods for schedules. Execute exports "runsched" to handle running or debugging the schedules. The user supplies one more module to define a defaults hash and the #! code can be 4 lines.
• Utilities includes logging, nastygrams, progress mail, directory sanity checks, local path generation.
• Config handles extracting relavant portions of the main config hash. This is mainly for use in methods since they can use "$que->moduleconfig" to get a hash of defaults useful in the current module.
• The S::D interface is unlikely to change at this point.
• 2do: The added modules need more POD and tests in test.pl.

0.33 Mon Mar 15 23:07:33 CST 2004

• Added use of @::ttyz to fork handler for easier debugging of multi-level forks. Pre-opened term's can be listed in the global variable, which is shifted off before each fork. This simplifies multi-level debugs (e.g., for groups).
• execute does a better job of handling non-zero group exits and die's. They are stored in the $que object along with being handed back via exit status.
• Doc bugs.

0.31 Sat Jan 4 21:40:03 CST 2003

• Fixed noabort mode (works like "make -k"). Passing in abort => 0 will not set the $que->{abort} value and will thus skip only jobs which depend on the one that failed.
• Comment cleanups.

0.30 Mon Nov 4 17:11:56 CST 2002

• Parallel::Depend::subque can also handle a hash referent
• Parallel::Depend::subque can also handle a hash referent as the schedule object.
• ref $_[0] eq 'ARRAY' allows passing the queue in as an array referent. Doesn't allow for blessed arrays, however, which should stringify into the schedule.
• added "ttylog" to avoid re-opening STDERR/STDOUT to .out and .err files. This puts everything from the scheule onto the tty. Mainly useful for debugging or where network interfaces might get cut off if there isn't any activitiy on the connection for too long.
• ttylog mode does not overwrite any existing log files (or create new ones). This avoids creating a directory full of empty logs or overwriting valid ones during a test run.
• Replaced the top-level que attributes (verbose, ttylog, force, ...) with $que->{attrib}. This is the single unit of inherited data for sub-queues.
• Added $que->{user} as inherited piece of sub-queues along with $que->{attrib}. The "user" entry is not managed in any other way by by S::D can be used to store information carried into sub-qeues, blessed, whatever.
• Minor internal bugfixes.
• Updated test.pl to handle new que syntax.

0.29 Thu Sep 12 19:31:32 CDT 2002

• Parallel::Depend::prepare will now take a hash ref as
• Parallel::Depend::prepare will now take a hash ref as the schedule argument. This allows the schedule to be a list, text scalar, or hash ref.

0.28 Thu Sep 12 19:31:11 CDT 2002

• Nothing, dealt with an upload screwup.

0.27 Tue Sep 10 14:32:58 CDT 2002

• Doc, comment cleanups.
• Cleaned up the distribution package a bit (Depend.pm now lives in lib/Schedule).

0.26 Thu Jun 6 09:06:45 CDT 2002

• debug argument avoids calling unalias, simply checks if the job list deadlocks. This will >>not<< process groups beyond determining if they deadlock w/in the main schedule. The main purpose for this is assuring that the log and run directories are in place and that the que doesn't obviously deadlock.
• nofork argument runs the que serially without forking. This is intended mainly for debugging and allows running scheduled using "perl -d" with impunity. It effectively limits the maxjobs to 1 since nothing is forked, the jobs are executed in an eval one by one.
• In order to avoid conflicts with the accessor methods, the "debug" sub has been renamed to "validate". If someone thinks of a better name warn me.
• POD updates.

0.25 Wed May 22 02:17:08 CDT 2002

• Blocking on job slots displays the blocked jobs if verbose > 1.
• Replace $que->{abort} with $que->{failure} to avoid confusion with $que->{noabort} switch value. Failed queues now have the message in $que->{failure}. This doesn't effect the external interface (aside from removing the "abort" accessor method and replacing it with "failure").
• Added "force" argument to override precheck croaking on non-empty pidfiles without an exit. Used with restart, it forces execution of anything without an exit status in the pidfile.
• Decided on group syntax. Using '::' for groups is problematic due to Perl's module notation; almost anything else might appear in a shell alias. Current notation is to enclose the jobs in angle-brackets ("<>") surrounded by whitespace. The closing delimeter makes it a bit more obvious that the group "encloses" the jobs.

                groupname < job1 job2 : job3 >
                groupname < job4 : job5 job6 >

        creates a single group with 6 jobs in it. Syntax for
        the group is a full scheudule. The default handler is
        group (i.e., groupname is aliased to "group" if none
        already exists when the group is processed).

        The group mechanism will look something like:

                Create a lookaside list for the group with the group's
                schedule in it. The schedule is keyed by the groupname.

                When the group becomes runnable then $que->group('groupname')
                is called, which prepares the schedule from the lookaside
                list and then executes it. If the groupname is aliased to
                another method then that one will be used to dispatch the
                group's schedule (e.g., $que->mygroup('groupname') via 
                "groupname = mygroup" in the schedule).

        The schedule then looks something like:

                transform = group       # optional, added automatically 

                transform < mungethis : mungethat >
                transform < mungeother : >

                transform : extract
                load : transform

        This creates a group with munge* jobs in it (they can be spread
        out however is most useful). The group handler converts this into
        something like:

                transform = group

                transform : extract
                load : transform

        When "transform" becomes runnable it is called via
        $que->group( 'transform' ) which calles subque with
        ( sched => 'mungethis mungethat mungeother :' ) then
        prepares executes the sub-que.

 -      More doc updates. They now reflect most of reality.
        Included example of using multi-line entries in the
        schedule via array ref.

 -      Fix typos in progress message trim, docs.

0.24

• unalias now returns an array of two items: the id string and a closure. the string is used in execute for displaying job status, the closure does the deed. This avoids the current stringified code referent going into the pidfile as the job identifier.
• Added "STUB" with behavior identical to PHONY (i.e., returns $job (STUB) immediately). Only purpose is to improve documentation during devleopment.
• Internal change to handle subque argument. This should not be visible if the "subque" argument is not passed to preapre.

0.23 Wed May 15 11:12:44 CDT 2002

• Add'l sanity check in prepare for assigning to maxjob: arguments only assign non-zero maxjob and only if maxjob is already zero. This avoids the prepare aruments overriding a schedule limit. Since zero is the default anyway this shouldn't cause any real pain.
• Minor boilerplate added to status sub.
• Comments.

0.22 Tue May 7 22:48:42 CDT 2002

• Added "informational" sub's to extract configuration and status of object:

alias()

alias( @items )

                        returns a copy of the alias hash (not the
                        original) or a hash slice of the requested
                        items from the hash.

                status()
                
                        Returns an anon. hash with the values of
                        alias(), restart, noabort, abort, verbose,
                        and debug keyed by their names.

                These are mainly useful for creating sub-queues with
                largely the same values as the parent.

                And single-value items:

                restart()       true/false if que is restarting
                noabort()       true/false if que is running noabort.
                abort()         current abort value (string).

                verbose()       integer of verbosity.
                debug()         true/false if in debug mode.

                jobz()          $jobz{$pid} = $job (i.e., pid => job string ).
                pidz()          $pidz{$pid} = $pidfilepath

                rundir()        path of run directory
                logdir()        path of log directory

 -      Minor cleanups.

0.21 Sat May 4 13:43:47 CDT 2002

• PHONY jobs don't pre-check pidfiles.
• Zero-size pidfiles are assumed non-running in restart mode, this saves having to blow off the unused pidfiles after a que is aborted via ^C.
• Few minor '==' code bugs.
• ^C handling via $SIG{INT} handler setting $que->{abort}.
• TERM handler forwards a SIGTERM to the process group; forked process sets $SIG{TERM} = 'DEFAULT'; if the child process needs any speical SIGTERM handling it will install that for itself on startup.
• Turned off warnings during the + 0 check in the child process to avoid logging warnings about non-numeric values.
• test.pl is in serious need of updates to check all of this properly.
• Minor code, comment cleanups.
• Remove Depndency on Text::Balanced.

0.19 Sat Apr 20 22:27:38 CDT 2002

• At this point the interface isn't going to change.
• Clean up unalias a bit, pushed lexicals into the if-ladder.
• Added croak ... unless $que at top of execute. Catches accidental re-runs quicker.
• Code allows unalias to be called as a class method. Main use of this is more automatic handling of the if-ladder for cases where a preliminary job has to be run outside of the schedule.
• Added eval to require the package for A::B-type aliases. This guarantees that $packag->can( $subroutine ) succeeds even if S::D doesn't already have the package available.
• Package::Subroutine alias handling includes an eval to require the sub in case it hasn't already been pulled in where unalias can see it.
• unalias always returns a code referent. handling of system calls is pushed into S::D->shellexec. This allows better logging of return values, since they actually mean something speicific. Also allows overloaded method to run better sanity checks before dispatching to the shell if the environment is better controlled.
• Slightly better testing in test.pl to account for some of the more offball alias formats.

0.18 Fri Apr 20 2002

• Comments, POD.

0.17 Pretend this never happend...

0.16 Wed Apr 17 20:54:30 CDT 2002

• Updated &precheck to use the last line of a pidfile if has >= 3 lines and perform a numeric comparison to 0 for the exit status. This allows for the child + parent both writing the status and sub's returning strings for successful execution.
• Put back the code that has the child writing the returned scalar to the pidfile unmodified. This will store any return strings from called sub's. Parent gets back $result + 0 and writes the numeric pic to the file. Either way, the next pass with precheck can use "$linz[-1] = 0" to determine if the job completed successfully.
• Removed Text::Balanced until I can find out why it returns a block for "/foo/bar". Using regex /^({.+})$/ to extract any blocks.

0.15 Tue Apr 16 12:13:59 CDT 2002

• Add the use of Text::Balanced::extract_codeblock to handle anon sub's in the aliases. This allows a schedule to contain valid perl blocks that will be compiled and executed at runtime.

  For example:

foo = { do_this($dir) || do_that($dir) or croak "$$: Neither that nor this!" }

...

foo : bar

        Will call the do_this or do_that sub's with the 
        value of $dir expanded in the parent process at
        runtime. 
        
        Note that the code must be on a single line.

        Since unalias() is called in the parent this can
        have side effects on subsequent children (e.g., 
        foo = {do_this(pop @dirlist)}). 

0.12 Fri Apr 12 14:05:41 CDT 2002

• Added handling for sub's named with packages for the calls. e.g., "Foo::Bar::bletch : frobnicate" will call the subroutine in that package if it exists. This requirs some change in the parser since it now has to detect colons that aren't followed by colons to perform the split (not difficult).

  At this point unalias can automatically detect methods, local subs and subs w/ package names before dispatching to the shell.

  Order of lookups is also changed, from Package::Sub through method to sub.

• Replaced assignment for $run with test for ref $que and defined $que->{alias}{$job}. This allows false values for placeholders and avoids problems if unalias is called as a class method.

0.11 Fri Apr 12 03:46:48 CDT 2002

• Stamped out some doc bugs. Mainly that the required argument is "sched" not "depend", empty aliases are no longer errors and bogus pod.

0.10 Thu Apr 11 14:16:40 CDT 2002

• Update unlias to search for $que->can( $run ) or __PACKAGE__->can($run)', using closures to call the method/sub with the aliased string as an argument. This allows scheduling of methods or subs by name without any modification to the S::D code.

  The mechanism for finding sub's is to unalis the jobname first, look for the ->can or CODE ref and pass it the original jobname if it's found.

  Thus

                abc : foo
                xyz : foo
                bar : foo

                bar : abc xyz

        to call foo('abc'), foo('xyz') and foo('bar').
        This might be useful for, say, cleaning up multiple
        directories. To pass more informaiton just use 
        the arguments as hash keys into a package/global
        value with the extra info.

 -      Assigning an empty or 'PHONY' alias is a noop.
        Thus:

                foo =

        or 

                foo = PHONY

        Will insert an immediate return of zero job into
        the schedule. This is mainly to neaten things up:

                foo =
                
                foo : long_named_job_one
                foo : even_longer_named_job_two
                foo : something_you_surely_do_not_want_to_type

                bar : foo

        now bar depends on all of the other three jobs without
        the line-from-hell in the middle of a schedule. This can
        also be handy for generating schedules on the fly, where
        bar is a placeholder and the others are pushed onto a 
        stack if they are needed.

 -      Doc updates.

0.09

        Put the tarball into a tarball rahter than 
        cpio archive, no change to the code.

0.08 Fri Apr 5 10:10:08 CST 2002

• Added runjob to handle the result of unalias after the fork. If the unaliased scalar is a code reference then it exits with the result of &$job; otherwise exec's $job.

  Using an unalias with:

                no strict 'refs';
                \&$job

        to expand the tag from the scheule allows 
        queueing subroutines -- or a mixture of
        subroutines and shell execs. This could also
        return a closure to push evaluation parameters
        even later into the cycle (or for testing).

        See notes for unalias & runjob for examples.

 -      Added switch for handling failed jobs without
        aborting the queue. This offers the same effect
        as "make -k". If "noabort => true" is passed
        into prepare then jobs that fail will have their
        dependencies marked for skipping and the pidfiles
        will get a nastygram + exit status of -1 (i.e.,
        they will be re-executed on a restart). 

        The noabort code doesn't seem to break anything,
        but has not been fully tested (yet).

 -      pidfile and output directories can be passed in with the arguments,
        picked up from the environment or default to the current
        executable's directory name. the environment method can be
        handy for the single-argument version.

 -      Serious updates to pod and comments.

0.07

        Default for $que->{alias}{logdir} and {rundir}
        are "dirname $0". Simplifies running multpile
        copies of the same file and schedule from 
        different directories via soft link.

        Revised exit status writing. The child uses
        system instead of exec and writes $? to its
        own pidfile; the parent writes $? to the pidfile
        if it is non-zero. This allows either the parent
        or child to get zapped by a signal, leave the
        other running and correctly record the status.
        It also means that the pidfiles may be 4 lines
        long on failure. Fix there is to read [0..2]
        to check the status on the way in for restarts.

        Updated comments to reflect reality a bit better.

0.06

        Remove some of the extra newlines -- they aren't
        required since individual job output goes to 
        stdout/stderr files.

        Shuffled verobse prints to a bit to give saner
        combinatins of output. At this point test.log 
        should give a reasonable idea of what slient,
        progress and detailed output look like.

        Process verbose as an alias for setting verbosity.

        Add sanity check for odd number of arg's > 1
        in prepare. Makes it harder to zap thyself by
        adding "verbose => X" after a single-value
        schedule entry.

        test.pl checks for forkatotis in the module by 
        comparing the initial pid running test.pl with
        what's running after the test_blah call; croaks
        if the pid has changed since test.pl startup.

        Updated comments, pod to reflect the changes 
        since 0.03.

        Note: Still need to come up with a reasonable
        definition for processing the debug alias/arg
        during prepare and execution. It may require
        debug levels like: 1 => don't fork, 2 => also
        don't check or write pidfiles. Problem there
        is making sure that mixing $que->debug with 
        $que->prepare( ... debug => X ) doesn't cause
        unnecessary errors.

0.05:

        Output of individual jobs goes to $logdir/$job.out
        and $logdir/$job.err. Main purpose is to keep the
        top-level schedule logs clean.

        test.pl puts stdout to test.log -- saves a lotta 
        stuff flying by on make test.

        verbose and debug arg's to prepare and execute
        are independent (i.e, you can now debug in silent
        mode and get minimal output).

0.04 Fri Mar 1 13:52:34 CST 2002

        debug uses copy of queue, doesn't consume original
        object during debug, returns original object if 
        debug is successful. see comments for use.

        updated verbose handling, now has three levels: 0, 1, 2.
        0 == stop/start messages and nastygrams, 1 == progress
        messages from fork/reap; 2 == fairly detailed.  $q->{verbose}
        overrides the debug switch; no verbose setting w/ debug
        gives verbose == 2. added description of changes to POD.

        all verbose-controlled output goes to STDOUT, nastygrams
        and que start/complete messages to STDERR.

        doc updates to reflect changes in verbosity.

0.03 Wed Feb 27 12:20:18 CST 2002

        Doc updates.
        test.pl updated.

0.02 Wed Feb 6 17:25:02 CST 2002

Release-able version.

0.01 Wed Feb 6 10:20:32 2002

Beta