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-rw-r--r--waflib/Tools/md5_tstamp.py39
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diff --git a/waflib/Tools/md5_tstamp.py b/waflib/Tools/md5_tstamp.py
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+#! /usr/bin/env python
+# encoding: utf-8
+
+"""
+Re-calculate md5 hashes of files only when the file times or the file
+size have changed.
+
+The hashes can also reflect either the file contents (STRONGEST=True) or the
+file time and file size.
+
+The performance benefits of this module are usually insignificant.
+"""
+
+import os, stat
+from waflib import Utils, Build, Node
+
+STRONGEST = True
+
+Build.SAVED_ATTRS.append('hashes_md5_tstamp')
+def h_file(self):
+ filename = self.abspath()
+ st = os.stat(filename)
+
+ cache = self.ctx.hashes_md5_tstamp
+ if filename in cache and cache[filename][0] == st.st_mtime:
+ return cache[filename][1]
+
+ if STRONGEST:
+ ret = Utils.h_file(filename)
+ else:
+ if stat.S_ISDIR(st[stat.ST_MODE]):
+ raise IOError('Not a file')
+ ret = Utils.md5(str((st.st_mtime, st.st_size)).encode()).digest()
+
+ cache[filename] = (st.st_mtime, ret)
+ return ret
+h_file.__doc__ = Node.Node.h_file.__doc__
+Node.Node.h_file = h_file
+