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Diffstat (limited to 'engine/SCons/Taskmaster.py')
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diff --git a/engine/SCons/Taskmaster.py b/engine/SCons/Taskmaster.py new file mode 100644 index 0000000..ac4b4d5 --- /dev/null +++ b/engine/SCons/Taskmaster.py @@ -0,0 +1,1049 @@ +# +# Copyright (c) 2001 - 2014 The SCons Foundation +# +# Permission is hereby granted, free of charge, to any person obtaining +# a copy of this software and associated documentation files (the +# "Software"), to deal in the Software without restriction, including +# without limitation the rights to use, copy, modify, merge, publish, +# distribute, sublicense, and/or sell copies of the Software, and to +# permit persons to whom the Software is furnished to do so, subject to +# the following conditions: +# +# The above copyright notice and this permission notice shall be included +# in all copies or substantial portions of the Software. +# +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY +# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE +# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND +# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE +# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION +# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION +# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + +__doc__ = """ +Generic Taskmaster module for the SCons build engine. + +This module contains the primary interface(s) between a wrapping user +interface and the SCons build engine. There are two key classes here: + + Taskmaster + This is the main engine for walking the dependency graph and + calling things to decide what does or doesn't need to be built. + + Task + This is the base class for allowing a wrapping interface to + decide what does or doesn't actually need to be done. The + intention is for a wrapping interface to subclass this as + appropriate for different types of behavior it may need. + + The canonical example is the SCons native Python interface, + which has Task subclasses that handle its specific behavior, + like printing "`foo' is up to date" when a top-level target + doesn't need to be built, and handling the -c option by removing + targets as its "build" action. There is also a separate subclass + for suppressing this output when the -q option is used. + + The Taskmaster instantiates a Task object for each (set of) + target(s) that it decides need to be evaluated and/or built. +""" + +__revision__ = "src/engine/SCons/Taskmaster.py 2014/09/27 12:51:43 garyo" + +from itertools import chain +import operator +import sys +import traceback + +import SCons.Errors +import SCons.Node +import SCons.Warnings + +StateString = SCons.Node.StateString +NODE_NO_STATE = SCons.Node.no_state +NODE_PENDING = SCons.Node.pending +NODE_EXECUTING = SCons.Node.executing +NODE_UP_TO_DATE = SCons.Node.up_to_date +NODE_EXECUTED = SCons.Node.executed +NODE_FAILED = SCons.Node.failed + +print_prepare = 0 # set by option --debug=prepare + +# A subsystem for recording stats about how different Nodes are handled by +# the main Taskmaster loop. There's no external control here (no need for +# a --debug= option); enable it by changing the value of CollectStats. + +CollectStats = None + +class Stats(object): + """ + A simple class for holding statistics about the disposition of a + Node by the Taskmaster. If we're collecting statistics, each Node + processed by the Taskmaster gets one of these attached, in which case + the Taskmaster records its decision each time it processes the Node. + (Ideally, that's just once per Node.) + """ + def __init__(self): + """ + Instantiates a Taskmaster.Stats object, initializing all + appropriate counters to zero. + """ + self.considered = 0 + self.already_handled = 0 + self.problem = 0 + self.child_failed = 0 + self.not_built = 0 + self.side_effects = 0 + self.build = 0 + +StatsNodes = [] + +fmt = "%(considered)3d "\ + "%(already_handled)3d " \ + "%(problem)3d " \ + "%(child_failed)3d " \ + "%(not_built)3d " \ + "%(side_effects)3d " \ + "%(build)3d " + +def dump_stats(): + for n in sorted(StatsNodes, key=lambda a: str(a)): + print (fmt % n.stats.__dict__) + str(n) + + + +class Task(object): + """ + Default SCons build engine task. + + This controls the interaction of the actual building of node + and the rest of the engine. + + This is expected to handle all of the normally-customizable + aspects of controlling a build, so any given application + *should* be able to do what it wants by sub-classing this + class and overriding methods as appropriate. If an application + needs to customze something by sub-classing Taskmaster (or + some other build engine class), we should first try to migrate + that functionality into this class. + + Note that it's generally a good idea for sub-classes to call + these methods explicitly to update state, etc., rather than + roll their own interaction with Taskmaster from scratch. + """ + def __init__(self, tm, targets, top, node): + self.tm = tm + self.targets = targets + self.top = top + self.node = node + self.exc_clear() + + def trace_message(self, method, node, description='node'): + fmt = '%-20s %s %s\n' + return fmt % (method + ':', description, self.tm.trace_node(node)) + + def display(self, message): + """ + Hook to allow the calling interface to display a message. + + This hook gets called as part of preparing a task for execution + (that is, a Node to be built). As part of figuring out what Node + should be built next, the actually target list may be altered, + along with a message describing the alteration. The calling + interface can subclass Task and provide a concrete implementation + of this method to see those messages. + """ + pass + + def prepare(self): + """ + Called just before the task is executed. + + This is mainly intended to give the target Nodes a chance to + unlink underlying files and make all necessary directories before + the Action is actually called to build the targets. + """ + global print_prepare + T = self.tm.trace + if T: T.write(self.trace_message(u'Task.prepare()', self.node)) + + # Now that it's the appropriate time, give the TaskMaster a + # chance to raise any exceptions it encountered while preparing + # this task. + self.exception_raise() + + if self.tm.message: + self.display(self.tm.message) + self.tm.message = None + + # Let the targets take care of any necessary preparations. + # This includes verifying that all of the necessary sources + # and dependencies exist, removing the target file(s), etc. + # + # As of April 2008, the get_executor().prepare() method makes + # sure that all of the aggregate sources necessary to build this + # Task's target(s) exist in one up-front check. The individual + # target t.prepare() methods check that each target's explicit + # or implicit dependencies exists, and also initialize the + # .sconsign info. + executor = self.targets[0].get_executor() + if executor is None: + return + executor.prepare() + for t in executor.get_action_targets(): + if print_prepare: + print "Preparing target %s..."%t + for s in t.side_effects: + print "...with side-effect %s..."%s + t.prepare() + for s in t.side_effects: + if print_prepare: + print "...Preparing side-effect %s..."%s + s.prepare() + + def get_target(self): + """Fetch the target being built or updated by this task. + """ + return self.node + + def needs_execute(self): + # TODO(deprecate): "return True" is the old default behavior; + # change it to NotImplementedError (after running through the + # Deprecation Cycle) so the desired behavior is explicitly + # determined by which concrete subclass is used. + #raise NotImplementedError + msg = ('Taskmaster.Task is an abstract base class; instead of\n' + '\tusing it directly, ' + 'derive from it and override the abstract methods.') + SCons.Warnings.warn(SCons.Warnings.TaskmasterNeedsExecuteWarning, msg) + return True + + def execute(self): + """ + Called to execute the task. + + This method is called from multiple threads in a parallel build, + so only do thread safe stuff here. Do thread unsafe stuff in + prepare(), executed() or failed(). + """ + T = self.tm.trace + if T: T.write(self.trace_message(u'Task.execute()', self.node)) + + try: + cached_targets = [] + for t in self.targets: + if not t.retrieve_from_cache(): + break + cached_targets.append(t) + if len(cached_targets) < len(self.targets): + # Remove targets before building. It's possible that we + # partially retrieved targets from the cache, leaving + # them in read-only mode. That might cause the command + # to fail. + # + for t in cached_targets: + try: + t.fs.unlink(t.path) + except (IOError, OSError): + pass + self.targets[0].build() + else: + for t in cached_targets: + t.cached = 1 + except SystemExit: + exc_value = sys.exc_info()[1] + raise SCons.Errors.ExplicitExit(self.targets[0], exc_value.code) + except SCons.Errors.UserError: + raise + except SCons.Errors.BuildError: + raise + except Exception, e: + buildError = SCons.Errors.convert_to_BuildError(e) + buildError.node = self.targets[0] + buildError.exc_info = sys.exc_info() + raise buildError + + def executed_without_callbacks(self): + """ + Called when the task has been successfully executed + and the Taskmaster instance doesn't want to call + the Node's callback methods. + """ + T = self.tm.trace + if T: T.write(self.trace_message('Task.executed_without_callbacks()', + self.node)) + + for t in self.targets: + if t.get_state() == NODE_EXECUTING: + for side_effect in t.side_effects: + side_effect.set_state(NODE_NO_STATE) + t.set_state(NODE_EXECUTED) + + def executed_with_callbacks(self): + """ + Called when the task has been successfully executed and + the Taskmaster instance wants to call the Node's callback + methods. + + This may have been a do-nothing operation (to preserve build + order), so we must check the node's state before deciding whether + it was "built", in which case we call the appropriate Node method. + In any event, we always call "visited()", which will handle any + post-visit actions that must take place regardless of whether + or not the target was an actual built target or a source Node. + """ + global print_prepare + T = self.tm.trace + if T: T.write(self.trace_message('Task.executed_with_callbacks()', + self.node)) + + for t in self.targets: + if t.get_state() == NODE_EXECUTING: + for side_effect in t.side_effects: + side_effect.set_state(NODE_NO_STATE) + t.set_state(NODE_EXECUTED) + if not t.cached: + t.push_to_cache() + t.built() + t.visited() + if (not print_prepare and + (not hasattr(self, 'options') or not self.options.debug_includes)): + t.release_target_info() + else: + t.visited() + + executed = executed_with_callbacks + + def failed(self): + """ + Default action when a task fails: stop the build. + + Note: Although this function is normally invoked on nodes in + the executing state, it might also be invoked on up-to-date + nodes when using Configure(). + """ + self.fail_stop() + + def fail_stop(self): + """ + Explicit stop-the-build failure. + + This sets failure status on the target nodes and all of + their dependent parent nodes. + + Note: Although this function is normally invoked on nodes in + the executing state, it might also be invoked on up-to-date + nodes when using Configure(). + """ + T = self.tm.trace + if T: T.write(self.trace_message('Task.failed_stop()', self.node)) + + # Invoke will_not_build() to clean-up the pending children + # list. + self.tm.will_not_build(self.targets, lambda n: n.set_state(NODE_FAILED)) + + # Tell the taskmaster to not start any new tasks + self.tm.stop() + + # We're stopping because of a build failure, but give the + # calling Task class a chance to postprocess() the top-level + # target under which the build failure occurred. + self.targets = [self.tm.current_top] + self.top = 1 + + def fail_continue(self): + """ + Explicit continue-the-build failure. + + This sets failure status on the target nodes and all of + their dependent parent nodes. + + Note: Although this function is normally invoked on nodes in + the executing state, it might also be invoked on up-to-date + nodes when using Configure(). + """ + T = self.tm.trace + if T: T.write(self.trace_message('Task.failed_continue()', self.node)) + + self.tm.will_not_build(self.targets, lambda n: n.set_state(NODE_FAILED)) + + def make_ready_all(self): + """ + Marks all targets in a task ready for execution. + + This is used when the interface needs every target Node to be + visited--the canonical example being the "scons -c" option. + """ + T = self.tm.trace + if T: T.write(self.trace_message('Task.make_ready_all()', self.node)) + + self.out_of_date = self.targets[:] + for t in self.targets: + t.disambiguate().set_state(NODE_EXECUTING) + for s in t.side_effects: + # add disambiguate here to mirror the call on targets above + s.disambiguate().set_state(NODE_EXECUTING) + + def make_ready_current(self): + """ + Marks all targets in a task ready for execution if any target + is not current. + + This is the default behavior for building only what's necessary. + """ + global print_prepare + T = self.tm.trace + if T: T.write(self.trace_message(u'Task.make_ready_current()', + self.node)) + + self.out_of_date = [] + needs_executing = False + for t in self.targets: + try: + t.disambiguate().make_ready() + is_up_to_date = not t.has_builder() or \ + (not t.always_build and t.is_up_to_date()) + except EnvironmentError, e: + raise SCons.Errors.BuildError(node=t, errstr=e.strerror, filename=e.filename) + + if not is_up_to_date: + self.out_of_date.append(t) + needs_executing = True + + if needs_executing: + for t in self.targets: + t.set_state(NODE_EXECUTING) + for s in t.side_effects: + # add disambiguate here to mirror the call on targets in first loop above + s.disambiguate().set_state(NODE_EXECUTING) + else: + for t in self.targets: + # We must invoke visited() to ensure that the node + # information has been computed before allowing the + # parent nodes to execute. (That could occur in a + # parallel build...) + t.visited() + t.set_state(NODE_UP_TO_DATE) + if (not print_prepare and + (not hasattr(self, 'options') or not self.options.debug_includes)): + t.release_target_info() + + make_ready = make_ready_current + + def postprocess(self): + """ + Post-processes a task after it's been executed. + + This examines all the targets just built (or not, we don't care + if the build was successful, or even if there was no build + because everything was up-to-date) to see if they have any + waiting parent Nodes, or Nodes waiting on a common side effect, + that can be put back on the candidates list. + """ + T = self.tm.trace + if T: T.write(self.trace_message(u'Task.postprocess()', self.node)) + + # We may have built multiple targets, some of which may have + # common parents waiting for this build. Count up how many + # targets each parent was waiting for so we can subtract the + # values later, and so we *don't* put waiting side-effect Nodes + # back on the candidates list if the Node is also a waiting + # parent. + + targets = set(self.targets) + + pending_children = self.tm.pending_children + parents = {} + for t in targets: + # A node can only be in the pending_children set if it has + # some waiting_parents. + if t.waiting_parents: + if T: T.write(self.trace_message(u'Task.postprocess()', + t, + 'removing')) + pending_children.discard(t) + for p in t.waiting_parents: + parents[p] = parents.get(p, 0) + 1 + + for t in targets: + if t.side_effects is not None: + for s in t.side_effects: + if s.get_state() == NODE_EXECUTING: + s.set_state(NODE_NO_STATE) + for p in s.waiting_parents: + parents[p] = parents.get(p, 0) + 1 + for p in s.waiting_s_e: + if p.ref_count == 0: + self.tm.candidates.append(p) + + for p, subtract in parents.items(): + p.ref_count = p.ref_count - subtract + if T: T.write(self.trace_message(u'Task.postprocess()', + p, + 'adjusted parent ref count')) + if p.ref_count == 0: + self.tm.candidates.append(p) + + for t in targets: + t.postprocess() + + # Exception handling subsystem. + # + # Exceptions that occur while walking the DAG or examining Nodes + # must be raised, but must be raised at an appropriate time and in + # a controlled manner so we can, if necessary, recover gracefully, + # possibly write out signature information for Nodes we've updated, + # etc. This is done by having the Taskmaster tell us about the + # exception, and letting + + def exc_info(self): + """ + Returns info about a recorded exception. + """ + return self.exception + + def exc_clear(self): + """ + Clears any recorded exception. + + This also changes the "exception_raise" attribute to point + to the appropriate do-nothing method. + """ + self.exception = (None, None, None) + self.exception_raise = self._no_exception_to_raise + + def exception_set(self, exception=None): + """ + Records an exception to be raised at the appropriate time. + + This also changes the "exception_raise" attribute to point + to the method that will, in fact + """ + if not exception: + exception = sys.exc_info() + self.exception = exception + self.exception_raise = self._exception_raise + + def _no_exception_to_raise(self): + pass + + def _exception_raise(self): + """ + Raises a pending exception that was recorded while getting a + Task ready for execution. + """ + exc = self.exc_info()[:] + try: + exc_type, exc_value, exc_traceback = exc + except ValueError: + exc_type, exc_value = exc + exc_traceback = None + raise exc_type, exc_value, exc_traceback + +class AlwaysTask(Task): + def needs_execute(self): + """ + Always returns True (indicating this Task should always + be executed). + + Subclasses that need this behavior (as opposed to the default + of only executing Nodes that are out of date w.r.t. their + dependencies) can use this as follows: + + class MyTaskSubclass(SCons.Taskmaster.Task): + needs_execute = SCons.Taskmaster.Task.execute_always + """ + return True + +class OutOfDateTask(Task): + def needs_execute(self): + """ + Returns True (indicating this Task should be executed) if this + Task's target state indicates it needs executing, which has + already been determined by an earlier up-to-date check. + """ + return self.targets[0].get_state() == SCons.Node.executing + + +def find_cycle(stack, visited): + if stack[-1] in visited: + return None + visited.add(stack[-1]) + for n in stack[-1].waiting_parents: + stack.append(n) + if stack[0] == stack[-1]: + return stack + if find_cycle(stack, visited): + return stack + stack.pop() + return None + + +class Taskmaster(object): + """ + The Taskmaster for walking the dependency DAG. + """ + + def __init__(self, targets=[], tasker=None, order=None, trace=None): + self.original_top = targets + self.top_targets_left = targets[:] + self.top_targets_left.reverse() + self.candidates = [] + if tasker is None: + tasker = OutOfDateTask + self.tasker = tasker + if not order: + order = lambda l: l + self.order = order + self.message = None + self.trace = trace + self.next_candidate = self.find_next_candidate + self.pending_children = set() + + def find_next_candidate(self): + """ + Returns the next candidate Node for (potential) evaluation. + + The candidate list (really a stack) initially consists of all of + the top-level (command line) targets provided when the Taskmaster + was initialized. While we walk the DAG, visiting Nodes, all the + children that haven't finished processing get pushed on to the + candidate list. Each child can then be popped and examined in + turn for whether *their* children are all up-to-date, in which + case a Task will be created for their actual evaluation and + potential building. + + Here is where we also allow candidate Nodes to alter the list of + Nodes that should be examined. This is used, for example, when + invoking SCons in a source directory. A source directory Node can + return its corresponding build directory Node, essentially saying, + "Hey, you really need to build this thing over here instead." + """ + try: + return self.candidates.pop() + except IndexError: + pass + try: + node = self.top_targets_left.pop() + except IndexError: + return None + self.current_top = node + alt, message = node.alter_targets() + if alt: + self.message = message + self.candidates.append(node) + self.candidates.extend(self.order(alt)) + node = self.candidates.pop() + return node + + def no_next_candidate(self): + """ + Stops Taskmaster processing by not returning a next candidate. + + Note that we have to clean-up the Taskmaster candidate list + because the cycle detection depends on the fact all nodes have + been processed somehow. + """ + while self.candidates: + candidates = self.candidates + self.candidates = [] + self.will_not_build(candidates) + return None + + def _validate_pending_children(self): + """ + Validate the content of the pending_children set. Assert if an + internal error is found. + + This function is used strictly for debugging the taskmaster by + checking that no invariants are violated. It is not used in + normal operation. + + The pending_children set is used to detect cycles in the + dependency graph. We call a "pending child" a child that is + found in the "pending" state when checking the dependencies of + its parent node. + + A pending child can occur when the Taskmaster completes a loop + through a cycle. For example, lets imagine a graph made of + three node (A, B and C) making a cycle. The evaluation starts + at node A. The taskmaster first consider whether node A's + child B is up-to-date. Then, recursively, node B needs to + check whether node C is up-to-date. This leaves us with a + dependency graph looking like: + + Next candidate \ + \ + Node A (Pending) --> Node B(Pending) --> Node C (NoState) + ^ | + | | + +-------------------------------------+ + + Now, when the Taskmaster examines the Node C's child Node A, + it finds that Node A is in the "pending" state. Therefore, + Node A is a pending child of node C. + + Pending children indicate that the Taskmaster has potentially + loop back through a cycle. We say potentially because it could + also occur when a DAG is evaluated in parallel. For example, + consider the following graph: + + + Node A (Pending) --> Node B(Pending) --> Node C (Pending) --> ... + | ^ + | | + +----------> Node D (NoState) --------+ + / + Next candidate / + + The Taskmaster first evaluates the nodes A, B, and C and + starts building some children of node C. Assuming, that the + maximum parallel level has not been reached, the Taskmaster + will examine Node D. It will find that Node C is a pending + child of Node D. + + In summary, evaluating a graph with a cycle will always + involve a pending child at one point. A pending child might + indicate either a cycle or a diamond-shaped DAG. Only a + fraction of the nodes ends-up being a "pending child" of + another node. This keeps the pending_children set small in + practice. + + We can differentiate between the two cases if we wait until + the end of the build. At this point, all the pending children + nodes due to a diamond-shaped DAG will have been properly + built (or will have failed to build). But, the pending + children involved in a cycle will still be in the pending + state. + + The taskmaster removes nodes from the pending_children set as + soon as a pending_children node moves out of the pending + state. This also helps to keep the pending_children set small. + """ + + for n in self.pending_children: + assert n.state in (NODE_PENDING, NODE_EXECUTING), \ + (str(n), StateString[n.state]) + assert len(n.waiting_parents) != 0, (str(n), len(n.waiting_parents)) + for p in n.waiting_parents: + assert p.ref_count > 0, (str(n), str(p), p.ref_count) + + + def trace_message(self, message): + return 'Taskmaster: %s\n' % message + + def trace_node(self, node): + return '<%-10s %-3s %s>' % (StateString[node.get_state()], + node.ref_count, + repr(str(node))) + + def _find_next_ready_node(self): + """ + Finds the next node that is ready to be built. + + This is *the* main guts of the DAG walk. We loop through the + list of candidates, looking for something that has no un-built + children (i.e., that is a leaf Node or has dependencies that are + all leaf Nodes or up-to-date). Candidate Nodes are re-scanned + (both the target Node itself and its sources, which are always + scanned in the context of a given target) to discover implicit + dependencies. A Node that must wait for some children to be + built will be put back on the candidates list after the children + have finished building. A Node that has been put back on the + candidates list in this way may have itself (or its sources) + re-scanned, in order to handle generated header files (e.g.) and + the implicit dependencies therein. + + Note that this method does not do any signature calculation or + up-to-date check itself. All of that is handled by the Task + class. This is purely concerned with the dependency graph walk. + """ + + self.ready_exc = None + + T = self.trace + if T: T.write(u'\n' + self.trace_message('Looking for a node to evaluate')) + + while True: + node = self.next_candidate() + if node is None: + if T: T.write(self.trace_message('No candidate anymore.') + u'\n') + return None + + node = node.disambiguate() + state = node.get_state() + + # For debugging only: + # + # try: + # self._validate_pending_children() + # except: + # self.ready_exc = sys.exc_info() + # return node + + if CollectStats: + if not hasattr(node, 'stats'): + node.stats = Stats() + StatsNodes.append(node) + S = node.stats + S.considered = S.considered + 1 + else: + S = None + + if T: T.write(self.trace_message(u' Considering node %s and its children:' % self.trace_node(node))) + + if state == NODE_NO_STATE: + # Mark this node as being on the execution stack: + node.set_state(NODE_PENDING) + elif state > NODE_PENDING: + # Skip this node if it has already been evaluated: + if S: S.already_handled = S.already_handled + 1 + if T: T.write(self.trace_message(u' already handled (executed)')) + continue + + executor = node.get_executor() + + try: + children = executor.get_all_children() + except SystemExit: + exc_value = sys.exc_info()[1] + e = SCons.Errors.ExplicitExit(node, exc_value.code) + self.ready_exc = (SCons.Errors.ExplicitExit, e) + if T: T.write(self.trace_message(' SystemExit')) + return node + except Exception, e: + # We had a problem just trying to figure out the + # children (like a child couldn't be linked in to a + # VariantDir, or a Scanner threw something). Arrange to + # raise the exception when the Task is "executed." + self.ready_exc = sys.exc_info() + if S: S.problem = S.problem + 1 + if T: T.write(self.trace_message(' exception %s while scanning children.\n' % e)) + return node + + children_not_visited = [] + children_pending = set() + children_not_ready = [] + children_failed = False + + for child in chain(executor.get_all_prerequisites(), children): + childstate = child.get_state() + + if T: T.write(self.trace_message(u' ' + self.trace_node(child))) + + if childstate == NODE_NO_STATE: + children_not_visited.append(child) + elif childstate == NODE_PENDING: + children_pending.add(child) + elif childstate == NODE_FAILED: + children_failed = True + + if childstate <= NODE_EXECUTING: + children_not_ready.append(child) + + + # These nodes have not even been visited yet. Add + # them to the list so that on some next pass we can + # take a stab at evaluating them (or their children). + children_not_visited.reverse() + self.candidates.extend(self.order(children_not_visited)) + #if T and children_not_visited: + # T.write(self.trace_message(' adding to candidates: %s' % map(str, children_not_visited))) + # T.write(self.trace_message(' candidates now: %s\n' % map(str, self.candidates))) + + # Skip this node if any of its children have failed. + # + # This catches the case where we're descending a top-level + # target and one of our children failed while trying to be + # built by a *previous* descent of an earlier top-level + # target. + # + # It can also occur if a node is reused in multiple + # targets. One first descends though the one of the + # target, the next time occurs through the other target. + # + # Note that we can only have failed_children if the + # --keep-going flag was used, because without it the build + # will stop before diving in the other branch. + # + # Note that even if one of the children fails, we still + # added the other children to the list of candidate nodes + # to keep on building (--keep-going). + if children_failed: + for n in executor.get_action_targets(): + n.set_state(NODE_FAILED) + + if S: S.child_failed = S.child_failed + 1 + if T: T.write(self.trace_message('****** %s\n' % self.trace_node(node))) + continue + + if children_not_ready: + for child in children_not_ready: + # We're waiting on one or more derived targets + # that have not yet finished building. + if S: S.not_built = S.not_built + 1 + + # Add this node to the waiting parents lists of + # anything we're waiting on, with a reference + # count so we can be put back on the list for + # re-evaluation when they've all finished. + node.ref_count = node.ref_count + child.add_to_waiting_parents(node) + if T: T.write(self.trace_message(u' adjusted ref count: %s, child %s' % + (self.trace_node(node), repr(str(child))))) + + if T: + for pc in children_pending: + T.write(self.trace_message(' adding %s to the pending children set\n' % + self.trace_node(pc))) + self.pending_children = self.pending_children | children_pending + + continue + + # Skip this node if it has side-effects that are + # currently being built: + wait_side_effects = False + for se in executor.get_action_side_effects(): + if se.get_state() == NODE_EXECUTING: + se.add_to_waiting_s_e(node) + wait_side_effects = True + + if wait_side_effects: + if S: S.side_effects = S.side_effects + 1 + continue + + # The default when we've gotten through all of the checks above: + # this node is ready to be built. + if S: S.build = S.build + 1 + if T: T.write(self.trace_message(u'Evaluating %s\n' % + self.trace_node(node))) + + # For debugging only: + # + # try: + # self._validate_pending_children() + # except: + # self.ready_exc = sys.exc_info() + # return node + + return node + + return None + + def next_task(self): + """ + Returns the next task to be executed. + + This simply asks for the next Node to be evaluated, and then wraps + it in the specific Task subclass with which we were initialized. + """ + node = self._find_next_ready_node() + + if node is None: + return None + + executor = node.get_executor() + if executor is None: + return None + + tlist = executor.get_all_targets() + + task = self.tasker(self, tlist, node in self.original_top, node) + try: + task.make_ready() + except: + # We had a problem just trying to get this task ready (like + # a child couldn't be linked in to a VariantDir when deciding + # whether this node is current). Arrange to raise the + # exception when the Task is "executed." + self.ready_exc = sys.exc_info() + + if self.ready_exc: + task.exception_set(self.ready_exc) + + self.ready_exc = None + + return task + + def will_not_build(self, nodes, node_func=lambda n: None): + """ + Perform clean-up about nodes that will never be built. Invokes + a user defined function on all of these nodes (including all + of their parents). + """ + + T = self.trace + + pending_children = self.pending_children + + to_visit = set(nodes) + pending_children = pending_children - to_visit + + if T: + for n in nodes: + T.write(self.trace_message(' removing node %s from the pending children set\n' % + self.trace_node(n))) + try: + while len(to_visit): + node = to_visit.pop() + node_func(node) + + # Prune recursion by flushing the waiting children + # list immediately. + parents = node.waiting_parents + node.waiting_parents = set() + + to_visit = to_visit | parents + pending_children = pending_children - parents + + for p in parents: + p.ref_count = p.ref_count - 1 + if T: T.write(self.trace_message(' removing parent %s from the pending children set\n' % + self.trace_node(p))) + except KeyError: + # The container to_visit has been emptied. + pass + + # We have the stick back the pending_children list into the + # taskmaster because the python 1.5.2 compatibility does not + # allow us to use in-place updates + self.pending_children = pending_children + + def stop(self): + """ + Stops the current build completely. + """ + self.next_candidate = self.no_next_candidate + + def cleanup(self): + """ + Check for dependency cycles. + """ + if not self.pending_children: + return + + nclist = [(n, find_cycle([n], set())) for n in self.pending_children] + + genuine_cycles = [ + node for node,cycle in nclist + if cycle or node.get_state() != NODE_EXECUTED + ] + if not genuine_cycles: + # All of the "cycles" found were single nodes in EXECUTED state, + # which is to say, they really weren't cycles. Just return. + return + + desc = 'Found dependency cycle(s):\n' + for node, cycle in nclist: + if cycle: + desc = desc + " " + " -> ".join(map(str, cycle)) + "\n" + else: + desc = desc + \ + " Internal Error: no cycle found for node %s (%s) in state %s\n" % \ + (node, repr(node), StateString[node.get_state()]) + + raise SCons.Errors.UserError(desc) + +# Local Variables: +# tab-width:4 +# indent-tabs-mode:nil +# End: +# vim: set expandtab tabstop=4 shiftwidth=4: |