[784] | 1 | import json |
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[778] | 2 | from invirt.common import * |
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[781] | 3 | from os.path import getmtime |
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[726] | 4 | |
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[771] | 5 | default_src_path = '/etc/invirt/master.yaml' |
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[781] | 6 | default_cache_path = '/var/lib/invirt/cache.json' |
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[726] | 7 | |
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[771] | 8 | def load(src_path = default_src_path, |
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| 9 | cache_path = default_cache_path, |
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| 10 | force_refresh = False): |
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| 11 | """ |
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| 12 | Try loading the configuration from the faster-to-load JSON cache at |
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| 13 | cache_path. If it doesn't exist or is outdated, load the configuration |
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| 14 | instead from the original YAML file at src_path and regenerate the cache. |
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| 15 | I assume I have the permissions to write to the cache directory. |
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| 16 | """ |
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| 17 | if force_refresh: |
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| 18 | do_refresh = True |
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| 19 | else: |
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| 20 | src_mtime = getmtime(src_path) |
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| 21 | try: cache_mtime = getmtime(cache_path) |
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| 22 | except OSError: do_refresh = True |
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| 23 | else: do_refresh = src_mtime > cache_mtime |
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| 24 | |
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[778] | 25 | if not do_refresh: |
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| 26 | # try reading from the cache first |
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[781] | 27 | try: cfg = with_closing(file(cache_path))(lambda f: json.read(f.read())) |
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[778] | 28 | except: do_refresh = True |
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| 29 | |
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[771] | 30 | if do_refresh: |
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[781] | 31 | # Atomically reload the source and regenerate the cache. The read and |
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| 32 | # write must be a single transaction, or a stale version may be |
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| 33 | # written. |
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| 34 | @with_lock_file('/var/lib/invirt/cache.lock') |
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| 35 | def cfg(): |
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[784] | 36 | import yaml |
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[792] | 37 | try: default_loader = yaml.CSafeLoader |
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| 38 | except: default_loader = yaml.SafeLoader |
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[781] | 39 | cfg = with_closing(file(src_path))(lambda f: yaml.load(f, default_loader)) |
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| 40 | try: with_closing(file(cache_path, 'w'))(lambda f: f.write(json.write(cfg))) |
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| 41 | except: pass # silent failure |
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| 42 | return cfg |
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[771] | 43 | return cfg |
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| 44 | |
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[778] | 45 | dicts = load() |
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| 46 | structs = dicts2struct(dicts) |
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| 47 | |
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[726] | 48 | # vim:et:sw=4:ts=4 |
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