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-rw-r--r--extras/why.py78
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+#! /usr/bin/env python
+# encoding: utf-8
+# Thomas Nagy, 2010 (ita)
+
+"""
+This tool modifies the task signature scheme to store and obtain
+information about the task execution (why it must run, etc)::
+
+ def configure(conf):
+ conf.load('why')
+
+After adding the tool, a full rebuild is necessary:
+waf clean build --zones=task
+"""
+
+from waflib import Task, Utils, Logs, Errors
+
+def signature(self):
+ # compute the result one time, and suppose the scan_signature will give the good result
+ try:
+ return self.cache_sig
+ except AttributeError:
+ pass
+
+ self.m = Utils.md5()
+ self.m.update(self.hcode)
+ id_sig = self.m.digest()
+
+ # explicit deps
+ self.m = Utils.md5()
+ self.sig_explicit_deps()
+ exp_sig = self.m.digest()
+
+ # env vars
+ self.m = Utils.md5()
+ self.sig_vars()
+ var_sig = self.m.digest()
+
+ # implicit deps / scanner results
+ self.m = Utils.md5()
+ if self.scan:
+ try:
+ self.sig_implicit_deps()
+ except Errors.TaskRescan:
+ return self.signature()
+ impl_sig = self.m.digest()
+
+ ret = self.cache_sig = impl_sig + id_sig + exp_sig + var_sig
+ return ret
+
+
+Task.Task.signature = signature
+
+old = Task.Task.runnable_status
+def runnable_status(self):
+ ret = old(self)
+ if ret == Task.RUN_ME:
+ try:
+ old_sigs = self.generator.bld.task_sigs[self.uid()]
+ except (KeyError, AttributeError):
+ Logs.debug("task: task must run as no previous signature exists")
+ else:
+ new_sigs = self.cache_sig
+ def v(x):
+ return Utils.to_hex(x)
+
+ Logs.debug('Task %r', self)
+ msgs = ['* Implicit or scanner dependency', '* Task code', '* Source file, explicit or manual dependency', '* Configuration data variable']
+ tmp = 'task: -> %s: %s %s'
+ for x in range(len(msgs)):
+ l = len(Utils.SIG_NIL)
+ a = new_sigs[x*l : (x+1)*l]
+ b = old_sigs[x*l : (x+1)*l]
+ if (a != b):
+ Logs.debug(tmp, msgs[x].ljust(35), v(a), v(b))
+ return ret
+Task.Task.runnable_status = runnable_status
+