Simplify how files are created in the cache directory

The "cache prefix" concept is not immediately clear, and it's
generally speaking best to centralize the construction of filenames
in the cache to the CacheDir class anyway.

Also, use SaveFile for writing the log file, instead of writing it
to a temporary file and then copying, which is unnecessary I/O.

1 files changed, 6 insertions, 11 deletions

diff --git a/morphlib/builder.py b/morphlib/builder.py
index ed7b4378..d1a7fbde 100644
--- a/morphlib/builder.py
+++ b/morphlib/builder.py
@@ -154,8 +154,7 @@ class BlobBuilder(object): # pragma: no cover
         self.settings = None
         self.real_msg = None
         self.cachedir = None
-        self.cache_basename = None
-        self.cache_prefix = None
+        self.cache_key = None
         self.tempdir = None
         self.factory = None
         self.logfile = None
@@ -184,7 +183,7 @@ class BlobBuilder(object): # pragma: no cover
         return builds.items()
 
     def filename(self, name):
-        return '%s.%s.%s' % (self.cache_prefix,
+        return '%s.%s.%s' % (self.cachedir.name(self.cache_key),
                              self.blob.morph.kind,
                              name)
 
@@ -211,7 +210,7 @@ class BlobBuilder(object): # pragma: no cover
 
     def write_cache_metadata(self, meta):
         self.msg('Writing metadata to the cache')
-        with self.cachedir.open(self.cache_basename + '.meta') as f:
+        with self.cachedir.open(self.cache_key, suffix='.meta') as f:
             json.dump(meta, f, indent=4)
             f.write('\n')
 
@@ -228,14 +227,11 @@ class BlobBuilder(object): # pragma: no cover
         self.write_cache_metadata(meta)
 
     def prepare_logfile(self):
-        filename = self.tempdir.join('%s.log' % self.blob.morph.name)
-        self.logfile = open(filename, 'w+', 0)
+        self.logfile = self.cachedir.open(self.cache_key, suffix='.log', 
+                                          mode='w+', buffering=0)
 
     def save_logfile(self):
         self.logfile.close()
-        filename = '%s.log' % self.cache_prefix
-        self.msg('Saving build log to %s' % filename)
-        shutil.copyfile(self.logfile.name, filename)
 
 
 class ChunkBuilder(BlobBuilder): # pragma: no cover
@@ -761,8 +757,7 @@ class Builder(object): # pragma: no cover
         builder.settings = self.settings
         builder.real_msg = self.msg
         builder.cachedir = self.cachedir
-        builder.cache_prefix = self.cachedir.name(cache_id)
-        builder.cache_basename = os.path.basename(builder.cache_prefix)
+        builder.cache_key = cache_id
         builder.tempdir = self.tempdir
         builder.factory = self.factory
         builder.dump_memory_profile = self.dump_memory_profile