Add an actual awesome worker structure.

To put messages on queues, use this:

    @job('normal')
    def foo(x, y):
        return x + y

    foo.delay(4, 5)

To run workers, start any number of these:

    $ python runworker.py high normal low

You can give arbitrary queue names, they are not limited to these
priority-based names.  They just serve as a useful example.

__init__.py

@@ -1,21 +1,40 @@
-from rdb import conn
+import uuid
 from pickle import loads, dumps
+from rdb import conn
+
+def to_queue_key(queue_name):
+    return 'rq:%s' % (queue_name,)
+
+class DelayedResult(object):
+    def __init__(self, key):
+        self.key = key
+        self._rv = None
+
+    @property
+    def return_value(self):
+        if self._rv is None:
+            rv = conn.get(self.key)
+            if rv is not None:
+                # cache the result
+                self._rv = loads(rv)
+        return self._rv
+
+
+class task(object):
+    def __init__(self, queue='normal'):
+        self.queue = queue
+
+    def __call__(self, f):
+        def delay(*args, **kwargs):
+            queue_key = to_queue_key(self.queue)
+            key = '%s:result:%s' % (queue_key, str(uuid.uuid4()))
+            if f.__module__ == '__main__':
+                raise ValueError('Functions from the __main__ module cannot be processed by workers.')
+            s = dumps((f, key, args, kwargs))
+            conn.rpush(queue_key, s)
+            return DelayedResult(key)
+        f.delay = delay
+        return f
+
 
-def queue_daemon(app, queue_keys, rv_ttl=500):
-    """Simple implementation of a Redis queue worker, based on
-    http://flask.pocoo.org/snippets/73/
 
-    Will listen endlessly on the given queue keys.
-    """
-    while True:
-        msg = conn.blpop(queue_keys)
-        func, key, args, kwargs = loads(msg[1])
-        try:
-            rv = func(*args, **kwargs)
-        except Exception, e:
-            rv = e
-        if rv is not None:
-            p = conn.pipeline()
-            conn.set(key, dumps(rv))
-            conn.expire(key, rv_ttl)
-            p.execute()

daemon.py

@@ -0,0 +1,17 @@
+from logbook import Logger
+from .worker import Worker
+
+def run_daemon(queue_keys, rv_ttl=500):
+    """Simple implementation of a Redis queue worker, based on
+    http://flask.pocoo.org/snippets/73/
+
+    Will listen endlessly on the given queue keys.
+    """
+    worker = Worker(queue_keys, rv_ttl)
+
+    log = Logger('worker')
+    log.info('Listening for messages on Redis queues:')
+    for key in queue_keys:
+        log.info('- %s' % (key,))
+
+    worker.work()

worker.py

@@ -0,0 +1,78 @@
+import sys
+import os
+import random
+import time
+import procname
+from logbook import Logger
+from pickle import loads, dumps
+from rdb import conn
+from . import to_queue_key
+
+class NoQueueError(Exception): pass
+
+class Worker(object):
+    def __init__(self, queue_names, rv_ttl=500):
+        self.queue_names = queue_names
+        self.rv_ttl = rv_ttl
+        self._working = False
+        self.log = Logger('worker')
+        self.validate_queues()
+
+    def validate_queues(self):
+        if not self.queue_names:
+            raise NoQueueError('Give each worker at least one queue.')
+
+    @property
+    def queue_keys(self):
+        return map(to_queue_key, self.queue_names)
+
+    def is_idle(self):
+        return not self.is_working()
+
+    def is_working(self):
+        return self._working
+
+    @property
+    def pid(self):
+        return os.getpid()
+
+    def procline(self, message):
+        self.log.debug(message)
+        procname.setprocname('rq: %s' % (message,))
+
+    def work(self):
+        while True:
+            self.procline('Waiting on %s' % (', '.join(self.queue_names),))
+            queue, msg = conn.blpop(self.queue_keys)
+            self.fork_and_perform_task(queue, msg)
+
+    def fork_and_perform_task(self, queue, msg):
+        child_pid = os.fork()
+        if child_pid == 0:
+            random.seed()
+            self.log = Logger('horse')
+            try:
+                self.procline('Processing work since %d' % (time.time(),))
+                self._working = True
+                self.perform_task(queue, msg)
+            except Exception, e:
+                self.log.exception(e)
+                sys.exit(1)
+            sys.exit(0)
+        else:
+            self.procline('Forked %d at %d' % (child_pid, time.time()))
+            os.waitpid(child_pid, 0)
+            self._working = False
+
+    def perform_task(self, queue, msg):
+        func, key, args, kwargs = loads(msg)
+        self.procline('Processing %s from %s since %s' % (func.__name__, queue, time.time()))
+        try:
+            rv = func(*args, **kwargs)
+        except Exception, e:
+            rv = e
+        if rv is not None:
+            p = conn.pipeline()
+            conn.set(key, dumps(rv))
+            conn.expire(key, self.rv_ttl)
+            p.execute()