1# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4"""The pipeline_worker functions of the build and test stage of the framework.
5
6Part of the Chrome build flags optimization.
7
8This module defines the helper and the worker. If there are duplicate tasks, for
9example t1 and t2, needs to be built/tested, one of them, for example t1, will
10be built/tested and the helper waits for the result of t1 and set the results of
11the other task, t2 here, to be the same as that of t1. Setting the result of t2
12to be the same as t1 is referred to as resolving the result of t2.
13The worker invokes the work method of the tasks that are not duplicate.
14"""
15
16__author__ = 'yuhenglong@google.com (Yuheng Long)'
17
18import pipeline_process
19
20
21def Helper(stage, done_dict, helper_queue, completed_queue, result_queue):
22  """Helper that filters duplicate tasks.
23
24  This method Continuously pulls duplicate tasks from the helper_queue. The
25  duplicate tasks need not be compiled/tested. This method also pulls completed
26  tasks from the worker queue and let the results of the duplicate tasks be the
27  same as their corresponding finished task.
28
29  Args:
30    stage: The current stage of the pipeline, for example, build stage or test
31      stage.
32    done_dict: A dictionary of tasks that are done. The key of the dictionary is
33      the identifier of the task. The value of the dictionary is the results of
34      performing the corresponding task.
35    helper_queue: A queue of duplicate tasks whose results need to be resolved.
36      This is a communication channel between the pipeline_process and this
37      helper process.
38    completed_queue: A queue of tasks that have been built/tested. The results
39      of these tasks are needed to resolve the results of the duplicate tasks.
40      This is the communication channel between the workers and this helper
41      process.
42    result_queue: After the results of the duplicate tasks have been resolved,
43      the duplicate tasks will be sent to the next stage via this queue.
44  """
45
46  # The list of duplicate tasks, the results of which need to be resolved.
47  waiting_list = []
48
49  while True:
50    # Pull duplicate task from the helper queue.
51    if not helper_queue.empty():
52      task = helper_queue.get()
53
54      if task == pipeline_process.POISONPILL:
55        # Poison pill means no more duplicate task from the helper queue.
56        break
57
58      # The task has not been performed before.
59      assert not task.Done(stage)
60
61      # The identifier of this task.
62      identifier = task.GetIdentifier(stage)
63
64      # If a duplicate task comes before the corresponding resolved results from
65      # the completed_queue, it will be put in the waiting list. If the result
66      # arrives before the duplicate task, the duplicate task will be resolved
67      # right away.
68      if identifier in done_dict:
69        # This task has been encountered before and the result is available. The
70        # result can be resolved right away.
71        task.SetResult(stage, done_dict[identifier])
72        result_queue.put(task)
73      else:
74        waiting_list.append(task)
75
76    # Check and get completed tasks from completed_queue.
77    GetResultFromCompletedQueue(stage, completed_queue, done_dict, waiting_list,
78                                result_queue)
79
80  # Wait to resolve the results of the remaining duplicate tasks.
81  while waiting_list:
82    GetResultFromCompletedQueue(stage, completed_queue, done_dict, waiting_list,
83                                result_queue)
84
85
86def GetResultFromCompletedQueue(stage, completed_queue, done_dict, waiting_list,
87                                result_queue):
88  """Pull results from the completed queue and resolves duplicate tasks.
89
90  Args:
91    stage: The current stage of the pipeline, for example, build stage or test
92      stage.
93    completed_queue: A queue of tasks that have been performed. The results of
94      these tasks are needed to resolve the results of the duplicate tasks. This
95      is the communication channel between the workers and this method.
96    done_dict: A dictionary of tasks that are done. The key of the dictionary is
97      the optimization flags of the task. The value of the dictionary is the
98      compilation results of the corresponding task.
99    waiting_list: The list of duplicate tasks, the results of which need to be
100      resolved.
101    result_queue: After the results of the duplicate tasks have been resolved,
102      the duplicate tasks will be sent to the next stage via this queue.
103
104  This helper method tries to pull a completed task from the completed queue.
105  If it gets a task from the queue, it resolves the results of all the relevant
106  duplicate tasks in the waiting list. Relevant tasks are the tasks that have
107  the same flags as the currently received results from the completed_queue.
108  """
109  # Pull completed task from the worker queue.
110  if not completed_queue.empty():
111    (identifier, result) = completed_queue.get()
112    done_dict[identifier] = result
113
114    tasks = [t for t in waiting_list if t.GetIdentifier(stage) == identifier]
115    for duplicate_task in tasks:
116      duplicate_task.SetResult(stage, result)
117      result_queue.put(duplicate_task)
118      waiting_list.remove(duplicate_task)
119
120
121def Worker(stage, task, helper_queue, result_queue):
122  """Worker that performs the task.
123
124  This method calls the work method of the input task and distribute the result
125  to the helper and the next stage.
126
127  Args:
128    stage: The current stage of the pipeline, for example, build stage or test
129      stage.
130    task: Input task that needs to be performed.
131    helper_queue: Queue that holds the completed tasks and the results. This is
132      the communication channel between the worker and the helper.
133    result_queue: Queue that holds the completed tasks and the results. This is
134      the communication channel between the worker and the next stage.
135  """
136
137  # The task has not been completed before.
138  assert not task.Done(stage)
139
140  task.Work(stage)
141  helper_queue.put((task.GetIdentifier(stage), task.GetResult(stage)))
142  result_queue.put(task)
143