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Alternate implementation that doesn't require the thread. Instead write the cache whenever sync_booklists is called, meaning the cache always be "almost right". Also, use a tmp file and atomic rename to prevent truncating the file if calibre dies while it is being written.

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This commit is contained in:
Charles Haley 2014-10-12 13:46:00 +02:00
parent 44ae1fbb76
commit c0c5cc31a6
1 changed files with 13 additions and 12 deletions
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25
src/calibre/devices/smart_device_app/driver.py
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@ -803,18 +803,18 @@ class SMART_DEVICE_APP(DeviceConfig, DevicePlugin):
traceback.print_exc()
def _write_metadata_cache(self):
from calibre.utils.date import now
self._debug()
from calibre.utils.date import now
now_ = now()
from calibre.utils.config import to_json
cache_file_name = os.path.join(cache_dir(),
'wireless_device_' + self.device_uuid +
'_metadata_cache.json')
try:
purged = 0
count = 0
with open(cache_file_name, mode='wb') as fd:
prefix = os.path.join(cache_dir(),
'wireless_device_' + self.device_uuid + '_metadata_cache')
with open(prefix + '.tmp', mode='wb') as fd:
for key,book in self.device_book_cache.iteritems():
if (now() - book['last_used']).days > self.PURGE_CACHE_ENTRIES_DAYS:
if (now_ - book['last_used']).days > self.PURGE_CACHE_ENTRIES_DAYS:
purged += 1
continue
json_metadata = defaultdict(dict)
@ -825,14 +825,12 @@ class SMART_DEVICE_APP(DeviceConfig, DevicePlugin):
fd.write(result)
fd.write('\n')
count += 1
self._debug('wrote', count, 'entries, purged', purged, 'entries')
self._debug('wrote', count, 'entries, purged', purged, 'entries')
from calibre.utils.filenames import atomic_rename
atomic_rename(fd.name, prefix + '.json')
except:
traceback.print_exc()
try:
if os.path.exists(cache_file_name):
os.remove(cache_file_name)
except:
traceback.print_exc()
def _make_metadata_cache_key(self, uuid, lpath_or_ext):
key = None
@ -1392,6 +1390,9 @@ class SMART_DEVICE_APP(DeviceConfig, DevicePlugin):
except:
self._debug('failed to set local copy of _last_read_date_')
traceback.print_exc()
# Write the cache here so that if we are interrupted on disconnect then the
# almost-latest info will be available.
self._write_metadata_cache()
@synchronous('sync_lock')
def eject(self):