1 | import json, yaml |
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2 | from os import error, makedirs |
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3 | from os.path import dirname, getmtime |
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4 | |
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5 | default_src_path = '/etc/invirt/master.yaml' |
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6 | default_cache_path = '/var/lib/invirt/invirt.json' |
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7 | |
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8 | try: default_loader = yaml.CSafeLoader |
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9 | except: default_loader = yaml.SafeLoader |
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10 | |
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11 | def wrap(rsrc, func): |
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12 | "Utility to that emulates with Python 2.5's `with closing(rsrc)`." |
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13 | try: return func(rsrc) |
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14 | finally: rsrc.close() |
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15 | |
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16 | def load(src_path = default_src_path, |
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17 | cache_path = default_cache_path, |
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18 | force_refresh = False): |
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19 | """ |
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20 | Try loading the configuration from the faster-to-load JSON cache at |
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21 | cache_path. If it doesn't exist or is outdated, load the configuration |
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22 | instead from the original YAML file at src_path and regenerate the cache. |
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23 | I assume I have the permissions to write to the cache directory. |
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24 | """ |
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25 | if force_refresh: |
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26 | do_refresh = True |
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27 | else: |
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28 | src_mtime = getmtime(src_path) |
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29 | try: cache_mtime = getmtime(cache_path) |
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30 | except OSError: do_refresh = True |
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31 | else: do_refresh = src_mtime > cache_mtime |
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32 | |
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33 | if do_refresh: |
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34 | # reload the source and regenerate the cache |
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35 | cfg = wrap(file(src_path), lambda f: yaml.load(f, default_loader)) |
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36 | wrap(file(cache_path, 'w'), lambda f: f.write(json.write(cfg))) |
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37 | else: |
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38 | cfg = wrap(file(cache_path), lambda f: json.read(f.read())) |
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39 | return cfg |
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40 | |
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41 | # vim:et:sw=4:ts=4 |
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