optimisemapproxycache.py

#!/usr/bin/env python

"""
Optimise JPEGs in a mapproxy cache with mozjpeg.

Remembers processed files so they are only processed once.

Find -mtime wouldn't work because optimising the files changes the mtime.
"""

import os
from subprocess import call

PATH = "/home/openstreetmap/mapproxy/"
MOZJPEG = "/usr/local/bin/mozjpeg"

PROCESSED_FILES_FILE = os.path.join(PATH, "mozjpeg_optimised_tiles.txt")
PROCESSED_FILES = set(line.strip() for line in open(PROCESSED_FILES_FILE))

CACHE_DATA = os.path.join(PATH, "cache_data")

with open(PROCESSED_FILES_FILE, "a") as pff:
    for root, dirs, files in os.walk(CACHE_DATA):
        for tilefile in files:
            if tilefile.endswith(".jpeg"):
                tilepath = os.path.join(root, tilefile)
                if tilepath not in PROCESSED_FILES:
                    call([MOZJPEG, "-copy", "none", "-outfile", tilepath, tilepath])
                    pff.write("%s\n" % tilepath)