From cc08185235a0375cf5488e2f21be064f41cfb5ba Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=BCrg=20Billeter?= <j@bitron.ch>
Date: Fri, 21 Jul 2017 13:25:40 +0200
Subject: element.py: Calculate effective cache key before calling plugin
 methods

---
 buildstream/_artifactcache/artifactcache.py |  6 +++---
 buildstream/element.py                      | 11 +++++++++--
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/buildstream/_artifactcache/artifactcache.py b/buildstream/_artifactcache/artifactcache.py
index a7208e8f2..4e0d70360 100644
--- a/buildstream/_artifactcache/artifactcache.py
+++ b/buildstream/_artifactcache/artifactcache.py
@@ -220,12 +220,12 @@ class ArtifactCache():
     #     element (Element): The Element commit an artifact for
     #     content (str): The element's content directory
     #
-    def commit(self, element, content):
+    def commit(self, key, weak_key, element, content):
         # tag with strong cache key based on dependency versions used for the build
-        ref = buildref(element, element._get_cache_key_for_build())
+        ref = buildref(element, key)
 
         # also store under weak cache key
-        weak_ref = buildref(element, element._get_cache_key(strength=_KeyStrength.WEAK))
+        weak_ref = buildref(element, weak_key)
 
         _ostree.commit(self.repo, content, ref, weak_ref)
 
diff --git a/buildstream/element.py b/buildstream/element.py
index 60e81fda1..0d0a68d8a 100644
--- a/buildstream/element.py
+++ b/buildstream/element.py
@@ -1015,6 +1015,11 @@ class Element(Plugin):
                 # The plugin's assemble() method may modify this, though.
                 self.__dynamic_public = self.__public
 
+                # Calculate effective cache key before calling plugin methods
+                # to ensure the key is not affected by any side-effects of
+                # these methods
+                effective_cache_key = self._get_cache_key_for_build()
+
                 # Call the abstract plugin methods
                 try:
                     # Step 1 - Configure
@@ -1067,7 +1072,7 @@ class Element(Plugin):
                     }
                     meta = {
                         'keys': {
-                            'strong': self._get_cache_key_for_build(),
+                            'strong': effective_cache_key,
                             'weak': self._get_cache_key(_KeyStrength.WEAK),
                             'dependencies': dependencies
                         },
@@ -1077,7 +1082,9 @@ class Element(Plugin):
                     _yaml.dump(_yaml.node_sanitize(meta), os.path.join(metadir, 'artifact.yaml'))
 
                     with self.timed_activity("Caching Artifact"):
-                        self.__artifacts.commit(self, assembledir)
+                        self.__artifacts.commit(effective_cache_key,
+                                                self._get_cache_key(strength=_KeyStrength.WEAK),
+                                                self, assembledir)
 
             # Finally cleanup the build dir
             shutil.rmtree(rootdir)
-- 
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