Reimplemented the gzip compression as a plugin.

Extending the Writer wasn't the complete answer because the static
generator also copies some files. Instead, I implemented the work as a
plugin that attaches to the finalized event.

pelican/plugins/gzip_cache.py

@@ -0,0 +1,78 @@
+# Copyright (c) 2012 Matt Layman
+'''A plugin to create .gz cache files for optimization.'''
+
+import gzip
+import logging
+import os
+
+from pelican import signals
+
+logger = logging.getLogger(__name__)
+
+# A list of file types to exclude from possible compression
+EXCLUDE_TYPES = [
+    # Compressed types
+    '.bz2',
+    '.gz',
+
+    # Audio types
+    '.aac',
+    '.flac',
+    '.mp3',
+    '.wma',
+
+    # Image types
+    '.gif',
+    '.jpg',
+    '.jpeg',
+    '.png',
+
+    # Video types
+    '.avi',
+    '.mov',
+    '.mp4',
+]
+
+def create_gzip_cache(pelican):
+    '''Create a gzip cache file for every file that a webserver would
+    reasonably want to cache (e.g., text type files).
+
+    :param pelican: The Pelican instance
+    '''
+    for dirpath, _, filenames in os.walk(pelican.settings['OUTPUT_PATH']):
+        for name in filenames:
+            if should_compress(name):
+                filepath = os.path.join(dirpath, name)
+                create_gzip_file(filepath)
+
+def should_compress(filename):
+    '''Check if the filename is a type of file that should be compressed.
+
+    :param filename: A file name to check against
+    '''
+    for extension in EXCLUDE_TYPES:
+        if filename.endswith(extension):
+            return False
+
+    return True
+
+def create_gzip_file(filepath):
+    '''Create a gzipped file in the same directory with a filepath.gz name.
+
+    :param filepath: A file to compress
+    '''
+    compressed_path = filepath + '.gz'
+
+    with open(filepath, 'rb') as uncompressed:
+        try:
+            logger.debug('Compressing: %s' % filepath)
+            compressed = gzip.open(compressed_path, 'wb')
+            compressed.writelines(uncompressed)
+        except Exception, ex:
+            logger.critical('Gzip compression failed: %s' % ex)
+        finally:
+            compressed.close()
+
+def register():
+    signals.finalized.connect(create_gzip_cache)
+