stuartl/tornado-gallery
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Code Issues Releases Wiki Activity

resizer: Avoid using mutex if already cached.

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Waiting for file I/O reading from cache is not nearly as expensive as
waiting for an image to be resized.
This commit is contained in:
Stuart Longland 2018-04-18 20:08:36 +10:00
parent 19b432cdb9
commit 7fd9c1a6a5
Signed by: stuartl
GPG Key ID: 6AA32EFB18079BAA
1 changed files with 42 additions and 21 deletions
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63
tornado_gallery/resizer.py
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@ -103,6 +103,15 @@ class ResizerPool(object):
self._log.debug('%s/%s target dimensions %d by %d',
gallery, photo, width, height)
# Determine where the file would be cached
(cache_dir, cache_name) = self._get_cache_name(gallery, photo,
width,height, quality, rotation, img_format)
# Do we have this file?
data = self._read_cache(orig_node, cache_dir, cache_name)
if data is not None:
raise Return((img_format, cache_name, data))
# Locate the lock for this photo.
mutex_key = (gallery, photo, width, height, quality, rotation,
img_format)
@ -136,22 +145,11 @@ class ResizerPool(object):
finally:
mutex.release()
def _do_resize(self, gallery, photo, width, height, quality,
def _get_cache_name(self, gallery, photo, width, height, quality,
rotation, img_format):
"""
Perform a resize of the image, and return the result.
Determine what the name of a cached resized image would be.
"""
img_format = ImageFormat(img_format)
log = self._log.getChild('%s/%s@%dx%d' \
% (gallery, photo, width, height))
log.debug('Resizing photo; quality %f, '\
'rotation %f, format %s',
quality, rotation, img_format.name)
# Determine the path to the original file.
orig_node = self._fs_node.join_node(gallery, photo)
# Determine the name of the cache file.
photo_noext = '.'.join(photo.split('.')[:-1])
cache_name = ('%(gallery)s-%(photo)s-'\
@ -166,12 +164,10 @@ class ResizerPool(object):
'ext': img_format.ext
}
cache_dir = self._cache_node.join(gallery, photo_noext)
log.debug('Resized file: %s in %s', cache_name, cache_dir)
return (cache_dir, cache_name)
# Ensure the directory exists
makedirs(cache_dir, exist_ok=True)
# Do we have this file?
def _read_cache(self, orig_node, cache_dir, cache_name):
# Do we have this file now?
cache_path = self._cache_node.join(cache_dir, cache_name)
try:
cache_node = self._cache_node[cache_path]
@ -179,13 +175,37 @@ class ResizerPool(object):
if (cache_node.stat.st_size > 0) and \
(cache_node.stat.st_mtime >= orig_node.stat.st_mtime):
# This will do. Re-use the existing file.
log.info('Returning cached result')
return (img_format, cache_name,
open(cache_node.abs_path, 'rb').read())
return open(cache_node.abs_path, 'rb').read()
except KeyError:
# We do not, press on!
pass
def _do_resize(self, gallery, photo, width, height, quality,
rotation, img_format):
"""
Perform a resize of the image, and return the result.
"""
img_format = ImageFormat(img_format)
(cache_dir, cache_name) = self._get_cache_name(gallery, photo,
width,height, quality, rotation, img_format)
log = self._log.getChild('%s/%s@%dx%d' \
% (gallery, photo, width, height))
log.debug('Resizing photo; quality %f, '\
'rotation %f, format %s; save as %s in %s',
quality, rotation, img_format.name, cache_name, cache_dir)
# Determine the path to the original file.
orig_node = self._fs_node.join_node(gallery, photo)
# Ensure the directory exists
makedirs(cache_dir, exist_ok=True)
# Do we have this file now?
data = self._read_cache(orig_node, cache_dir, cache_name)
if data is not None:
return (img_format, cache_name, data)
# Open the image
img = Image.open(open(orig_node.abs_path,'rb'))
@ -200,6 +220,7 @@ class ResizerPool(object):
img = img.convert('RGB')
# Write out the new file.
cache_path = self._cache_node.join(cache_dir, cache_name)
img.save(open(cache_path,'wb'), img_format.pil_fmt)
# Return to caller