Merge "Add a mini-cinder volume create with resumption"

taskflow/examples/resume_volume_create.py

@@ -0,0 +1,153 @@
+# -*- coding: utf-8 -*-
+
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+#    Copyright (C) 2013 Yahoo! Inc. All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import contextlib
+import hashlib
+import logging
+import os
+import random
+import sys
+import time
+
+logging.basicConfig(level=logging.ERROR)
+
+top_dir = os.path.abspath(os.path.join(os.path.dirname(__file__),
+                                       os.pardir,
+                                       os.pardir))
+sys.path.insert(0, top_dir)
+
+from taskflow.patterns import graph_flow as gf
+from taskflow.patterns import linear_flow as lf
+
+from taskflow import engines
+from taskflow import task
+
+from taskflow.persistence import backends
+from taskflow.utils import eventlet_utils as e_utils
+from taskflow.utils import persistence_utils as p_utils
+
+
+@contextlib.contextmanager
+def slow_down(how_long=0.5):
+    try:
+        yield how_long
+    finally:
+        print("** Ctrl-c me please!!! **")
+        time.sleep(how_long)
+
+
+def find_flow_detail(backend, book_id, flow_id):
+    with contextlib.closing(backend.get_connection()) as conn:
+        lb = conn.get_logbook(book_id)
+        return lb.find(flow_id)
+
+
+def get_backend():
+    try:
+        backend_uri = sys.argv[1]
+    except Exception:
+        backend_uri = 'sqlite://'
+
+    backend = backends.fetch({'connection': backend_uri})
+    backend.get_connection().upgrade()
+    return backend
+
+
+class PrintText(task.Task):
+    def __init__(self, print_what, no_slow=False):
+        content_hash = hashlib.md5(print_what).hexdigest()[0:8]
+        super(PrintText, self).__init__(name="Print: %s" % (content_hash))
+        self._text = print_what
+        self._no_slow = no_slow
+
+    def execute(self):
+        if self._no_slow:
+            print("-" * (len(self._text)))
+            print(self._text)
+            print("-" * (len(self._text)))
+        else:
+            with slow_down():
+                print("-" * (len(self._text)))
+                print(self._text)
+                print("-" * (len(self._text)))
+
+
+class CreateSpecForVolumes(task.Task):
+    def execute(self):
+        volumes = []
+        for i in range(0, random.randint(1, 10)):
+            volumes.append({
+                'type': 'disk',
+                'location': "/dev/vda%s" % (i + 1),
+            })
+        return volumes
+
+
+class PrepareVolumes(task.Task):
+    def execute(self, volume_specs):
+        for v in volume_specs:
+            with slow_down():
+                print("Dusting off your hard drive %s" % (v))
+            with slow_down():
+                print("Taking a well deserved break.")
+            print("Your drive %s has been certified." % (v))
+
+
+# Setup the set of things to do (mini-cinder).
+flow = lf.Flow("root").add(
+    PrintText("Starting volume create", no_slow=True),
+    gf.Flow('maker').add(
+        CreateSpecForVolumes("volume_specs", provides='volume_specs'),
+        PrintText("I need a nap, it took me a while to build those specs."),
+        PrepareVolumes(),
+    ),
+    PrintText("Finished volume create", no_slow=True))
+
+# Setup the persistence & resumption layer.
+backend = get_backend()
+try:
+    book_id, flow_id = sys.argv[2].split("+", 1)
+except (IndexError, ValueError):
+    book_id = None
+    flow_id = None
+
+if not all([book_id, flow_id]):
+    logbook = p_utils.temporary_log_book(backend)
+    flow_detail = p_utils.create_flow_detail(flow, logbook, backend)
+    print("!! Your tracking id is: '%s+%s'" % (logbook.uuid, flow_detail.uuid))
+    print("!! Please submit this on later runs for tracking purposes")
+else:
+    flow_detail = find_flow_detail(backend, book_id, flow_id)
+
+# Annnnd load and run.
+engine = engines.load(flow,
+                      flow_detail=flow_detail,
+                      backend=backend,
+                      engine_conf={
+                          'engine': 'parallel',
+                          'executor': e_utils.GreenExecutor(10),
+                      })
+engine.run()
+
+# How to use.
+#
+# 1. $ python me.py "sqlite:////tmp/cinder.db"
+# 2. ctrl-c before this finishes
+# 3. Find the tracking id (search for 'Your tracking id is')
+# 4. $ python me.py "sqlite:////tmp/cinder.db" "$tracking_id"
+# 5. Profit!