source: vendor/current/buildtools/wafsamba/nothreads.py

# encoding: utf-8
# Thomas Nagy, 2005-2008 (ita)

# this replaces the core of Runner.py in waf with a varient that works
# on systems with completely broken threading (such as Python 2.5.x on
# AIX). For simplicity we enable this when JOBS=1, which is triggered
# by the compatibility makefile used for the waf build. That also ensures
# this code is tested, as it means it is used in the build farm, and by
# anyone using 'make' to build Samba with waf

"Execute the tasks"

import sys, random, threading
try: from Queue import Queue
except ImportError: from queue import Queue
import Utils, Options
from Constants import EXCEPTION, CRASHED, MAXJOBS, ASK_LATER, SKIPPED, SKIP_ME, SUCCESS

GAP = 15

run_old = threading.Thread.run
def run(*args, **kwargs):
    try:
        run_old(*args, **kwargs)
    except (KeyboardInterrupt, SystemExit):
        raise
    except:
        sys.excepthook(*sys.exc_info())
threading.Thread.run = run


class TaskConsumer(object):
    consumers = 1

def process(tsk):
    m = tsk.master
    if m.stop:
        m.out.put(tsk)
        return

    try:
        tsk.generator.bld.printout(tsk.display())
        if tsk.__class__.stat: ret = tsk.__class__.stat(tsk)
        # actual call to task's run() function
        else: ret = tsk.call_run()
    except Exception, e:
        tsk.err_msg = Utils.ex_stack()
        tsk.hasrun = EXCEPTION

        # TODO cleanup
        m.error_handler(tsk)
        m.out.put(tsk)
        return

    if ret:
        tsk.err_code = ret
        tsk.hasrun = CRASHED
    else:
        try:
            tsk.post_run()
        except Utils.WafError:
            pass
        except Exception:
            tsk.err_msg = Utils.ex_stack()
            tsk.hasrun = EXCEPTION
        else:
            tsk.hasrun = SUCCESS
    if tsk.hasrun != SUCCESS:
        m.error_handler(tsk)

    m.out.put(tsk)

class Parallel(object):
    """
    keep the consumer threads busy, and avoid consuming cpu cycles
    when no more tasks can be added (end of the build, etc)
    """
    def __init__(self, bld, j=2):

        # number of consumers
        self.numjobs = j

        self.manager = bld.task_manager
        self.manager.current_group = 0

        self.total = self.manager.total()

        # tasks waiting to be processed - IMPORTANT
        self.outstanding = []
        self.maxjobs = MAXJOBS

        # tasks that are awaiting for another task to complete
        self.frozen = []

        # tasks returned by the consumers
        self.out = Queue(0)

        self.count = 0 # tasks not in the producer area

        self.processed = 1 # progress indicator

        self.stop = False # error condition to stop the build
        self.error = False # error flag

    def get_next(self):
        "override this method to schedule the tasks in a particular order"
        if not self.outstanding:
            return None
        return self.outstanding.pop(0)

    def postpone(self, tsk):
        "override this method to schedule the tasks in a particular order"
        # TODO consider using a deque instead
        if random.randint(0, 1):
            self.frozen.insert(0, tsk)
        else:
            self.frozen.append(tsk)

    def refill_task_list(self):
        "called to set the next group of tasks"

        while self.count > self.numjobs + GAP or self.count >= self.maxjobs:
            self.get_out()

        while not self.outstanding:
            if self.count:
                self.get_out()

            if self.frozen:
                self.outstanding += self.frozen
                self.frozen = []
            elif not self.count:
                (jobs, tmp) = self.manager.get_next_set()
                if jobs is not None:
                    self.maxjobs = jobs
                if tmp:
                    self.outstanding += tmp
                break

    def get_out(self):
        "the tasks that are put to execute are all collected using get_out"
        ret = self.out.get()
        self.manager.add_finished(ret)
        if not self.stop and getattr(ret, 'more_tasks', None):
            self.outstanding += ret.more_tasks
            self.total += len(ret.more_tasks)
        self.count -= 1

    def error_handler(self, tsk):
        "by default, errors make the build stop (not thread safe so be careful)"
        if not Options.options.keep:
            self.stop = True
        self.error = True

    def start(self):
        "execute the tasks"

        while not self.stop:

            self.refill_task_list()

            # consider the next task
            tsk = self.get_next()
            if not tsk:
                if self.count:
                    # tasks may add new ones after they are run
                    continue
                else:
                    # no tasks to run, no tasks running, time to exit
                    break

            if tsk.hasrun:
                # if the task is marked as "run", just skip it
                self.processed += 1
                self.manager.add_finished(tsk)
                continue

            try:
                st = tsk.runnable_status()
            except Exception, e:
                self.processed += 1
                if self.stop and not Options.options.keep:
                    tsk.hasrun = SKIPPED
                    self.manager.add_finished(tsk)
                    continue
                self.error_handler(tsk)
                self.manager.add_finished(tsk)
                tsk.hasrun = EXCEPTION
                tsk.err_msg = Utils.ex_stack()
                continue

            if st == ASK_LATER:
                self.postpone(tsk)
            elif st == SKIP_ME:
                self.processed += 1
                tsk.hasrun = SKIPPED
                self.manager.add_finished(tsk)
            else:
                # run me: put the task in ready queue
                tsk.position = (self.processed, self.total)
                self.count += 1
                self.processed += 1
                tsk.master = self

                process(tsk)

        # self.count represents the tasks that have been made available to the consumer threads
        # collect all the tasks after an error else the message may be incomplete
        while self.error and self.count:
            self.get_out()

        #print loop
        assert (self.count == 0 or self.stop)


# enable nothreads
import Runner
Runner.process = process
Runner.Parallel = Parallel