From 324ef87b2d397764d7ae502f3ce82bd2ff40854b Mon Sep 17 00:00:00 2001
From: Jannis Leidel <jannis@leidel.info>
Date: Wed, 2 Jun 2010 12:15:34 +0200
Subject: [PATCH] Added optional caching of mtime checks. Set
 COMPRESS_MTIME_DELAY to the amount of time (in seconds) to cache the getmtime
 results.

---
 compressor/__init__.py            | 13 ++++++++++++-
 compressor/conf/settings.py       |  3 +++
 compressor/filters/css_default.py |  4 ++--
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/compressor/__init__.py b/compressor/__init__.py
index 4bd52d5..e52b92a 100644
--- a/compressor/__init__.py
+++ b/compressor/__init__.py
@@ -5,6 +5,7 @@ from django import template
 from django.conf import settings as django_settings
 from django.template.loader import render_to_string
 
+from django.core.cache import cache
 from django.core.files.base import ContentFile
 from django.core.files.storage import get_storage_class
 
@@ -28,6 +29,16 @@ def get_hexdigest(plaintext):
         return sha.new(plaintext).hexdigest()
 
 
+def get_mtime(filename):
+    if settings.MTIME_DELAY:
+        key = "django_compressor.mtime.%s" % filename
+        mtime = cache.get(key)
+        if mtime is None:
+            mtime = os.path.getmtime(filename)
+            cache.set(key, mtime, settings.MTIME_DELAY)
+        return mtime
+    return os.path.getmtime(filename)
+
 class Compressor(object):
 
     def __init__(self, content, output_prefix="compressed"):
@@ -53,7 +64,7 @@ class Compressor(object):
 
     @property
     def mtimes(self):
-        return [os.path.getmtime(h[1]) for h in self.split_contents() if h[0] == 'file']
+        return [get_mtime(h[1]) for h in self.split_contents() if h[0] == 'file']
 
     @property
     def cachekey(self):
diff --git a/compressor/conf/settings.py b/compressor/conf/settings.py
index 3925e2c..d65d4f6 100644
--- a/compressor/conf/settings.py
+++ b/compressor/conf/settings.py
@@ -27,3 +27,6 @@ REBUILD_TIMEOUT = getattr(settings, 'COMPRESS_REBUILD_TIMEOUT', 2592000) # 30 da
 # the upper bound on how long any compression should take to be generated
 # (used against dog piling, should be a lot smaller than REBUILD_TIMEOUT
 MINT_DELAY = getattr(settings, 'COMPRESS_MINT_DELAY', 30) # 30 seconds
+
+# check for file changes only after a delay (in seconds, disabled by default)
+MTIME_DELAY = getattr(settings, 'COMPRESS_MTIME_DELAY', None)
diff --git a/compressor/filters/css_default.py b/compressor/filters/css_default.py
index 0b33039..fca6e87 100644
--- a/compressor/filters/css_default.py
+++ b/compressor/filters/css_default.py
@@ -4,7 +4,7 @@ import posixpath
 
 from compressor.filters import FilterBase, FilterError
 from compressor.conf import settings
-from compressor import get_hexdigest
+from compressor import get_hexdigest, get_mtime
 
 class CssAbsoluteFilter(FilterBase):
     def input(self, filename=None, **kwargs):
@@ -17,7 +17,7 @@ class CssAbsoluteFilter(FilterBase):
         self.media_path = self.media_path.lstrip('/')
         self.media_url = settings.MEDIA_URL.rstrip('/')
         try:
-            mtime = os.path.getmtime(filename)
+            mtime = get_mtime(filename)
             self.mtime = get_hexdigest(str(int(mtime)))[:12]
         except OSError:
             self.mtime = None