gecko-dev/taskcluster/taskgraph/generator.py

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

from __future__ import absolute_import, print_function, unicode_literals
import logging
import os
import yaml

from .graph import Graph
from .types import TaskGraph

logger = logging.getLogger(__name__)

class TaskGraphGenerator(object):
    """
    The central controller for taskgraph.  This handles all phases of graph
    generation.  The task is generated from all of the kinds defined in
    subdirectories of the generator's root directory.

    Access to the results of this generation, as well as intermediate values at
    various phases of generation, is available via properties.  This encourages
    the provision of all generation inputs at instance construction time.
    """

    # Task-graph generation is implemented as a Python generator that yields
    # each "phase" of generation.  This allows some mach subcommands to short-
    # circuit generation of the entire graph by never completing the generator.

    def __init__(self, root_dir, parameters,
                 target_tasks_method):
        """
        @param root_dir: root directory, with subdirectories for each kind
        @param parameters: parameters for this task-graph generation
        @type parameters: dict
        @param target_tasks_method: function to determine the target_task_set;
                see `./target_tasks.py`.
        @type target_tasks_method: function
        """

        self.root_dir = root_dir
        self.parameters = parameters
        self.target_tasks_method = target_tasks_method

        # this can be set up until the time the target task set is generated;
        # it defaults to parameters['target_tasks']
        self._target_tasks = parameters.get('target_tasks')

        # start the generator
        self._run = self._run()
        self._run_results = {}

    @property
    def full_task_set(self):
        """
        The full task set: all tasks defined by any kind (a graph without edges)

        @type: TaskGraph
        """
        return self._run_until('full_task_set')


    @property
    def full_task_graph(self):
        """
        The full task graph: the full task set, with edges representing
        dependencies.

        @type: TaskGraph
        """
        return self._run_until('full_task_graph')

    @property
    def target_task_set(self):
        """
        The set of targetted tasks (a graph without edges)

        @type: TaskGraph
        """
        return self._run_until('target_task_set')

    @property
    def target_task_graph(self):
        """
        The set of targetted tasks and all of their dependencies

        @type: TaskGraph
        """
        return self._run_until('target_task_graph')

    @property
    def optimized_task_graph(self):
        """
        The set of targetted tasks and all of their dependencies; tasks that
        have been optimized out are either omitted or replaced with a Task
        instance containing only a task_id.

        @type: TaskGraph
        """
        return self._run_until('optimized_task_graph')

    def _load_kinds(self):
        for path in os.listdir(self.root_dir):
            path = os.path.join(self.root_dir, path)
            if not os.path.isdir(path):
                continue
            name = os.path.basename(path)
            logger.debug("loading kind `{}` from `{}`".format(name, path))

            kind_yml = os.path.join(path, 'kind.yml')
            with open(kind_yml) as f:
                config = yaml.load(f)

            # load the class defined by implementation
            try:
                impl = config['implementation']
            except KeyError:
                raise KeyError("{!r} does not define implementation".format(kind_yml))
            if impl.count(':') != 1:
                raise TypeError('{!r} implementation does not have the form "module:object"'
                                .format(kind_yml))

            impl_module, impl_object = impl.split(':')
            impl_class = __import__(impl_module)
            for a in impl_module.split('.')[1:]:
                impl_class = getattr(impl_class, a)
            for a in impl_object.split('.'):
                impl_class = getattr(impl_class, a)

            yield impl_class(path, config)

    def _run(self):
        all_tasks = {}
        for kind in self._load_kinds():
            for task in kind.load_tasks(self.parameters):
                if task.label in all_tasks:
                    raise Exception("duplicate tasks with label " + task.label)
                all_tasks[task.label] = task

        full_task_set = TaskGraph(all_tasks, Graph(set(all_tasks), set()))
        yield 'full_task_set', full_task_set

        edges = set()
        for t in full_task_set:
            for dep, depname in t.kind.get_task_dependencies(t, full_task_set):
                edges.add((t.label, dep, depname))

        full_task_graph = TaskGraph(all_tasks,
                                    Graph(full_task_set.graph.nodes, edges))
        yield 'full_task_graph', full_task_graph

        target_tasks = set(self.target_tasks_method(full_task_graph, self.parameters))

        target_task_set = TaskGraph(
            {l: all_tasks[l] for l in target_tasks},
            Graph(target_tasks, set()))
        yield 'target_task_set', target_task_set

        target_graph = full_task_graph.graph.transitive_closure(target_tasks)
        target_task_graph = TaskGraph(
            {l: all_tasks[l] for l in target_graph.nodes},
            target_graph)
        yield 'target_task_graph', target_task_graph

        # optimization is not yet implemented

        yield 'optimized_task_graph', target_task_graph

    def _run_until(self, name):
        while name not in self._run_results:
            try:
                k, v = self._run.next()
            except StopIteration:
                raise AttributeError("No such run result {}".format(name))
            self._run_results[k] = v
        return self._run_results[name]