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borg mount: cache partially read data chunks

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Fixes #966
This commit is contained in:
Marian Beermann 2016-04-23 18:03:05 +02:00
parent 528913b220
commit bfb00dfa01
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GPG key ID: 9B8450B91D1362C1
2 changed files with 22 additions and 1 deletions
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5
borg/archiver.py
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@ -1533,6 +1533,11 @@ def build_parser(self, args=None, prog=None):
To allow a regular user to use fstab entries, add the ``user`` option: To allow a regular user to use fstab entries, add the ``user`` option:
``/path/to/repo /mnt/point fuse.borgfs defaults,noauto,user 0 0`` ``/path/to/repo /mnt/point fuse.borgfs defaults,noauto,user 0 0``
The BORG_MOUNT_DATA_CACHE_ENTRIES environment variable is meant for advanced users
to tweak the performance. It sets the number of cached data chunks; additional
memory usage can be up to ~8 MiB times this number. The default is the number
of CPU cores.
""") """)
subparser = subparsers.add_parser('mount', parents=[common_parser], add_help=False, subparser = subparsers.add_parser('mount', parents=[common_parser], add_help=False,
description=self.do_mount.__doc__, description=self.do_mount.__doc__,

16
borg/fuse.py
View file

@ -8,9 +8,13 @@
import time import time
from .archive import Archive from .archive import Archive
from .helpers import daemonize, bigint_to_int from .helpers import daemonize, bigint_to_int
from .logger import create_logger
from .lrucache import LRUCache
from distutils.version import LooseVersion from distutils.version import LooseVersion
import msgpack import msgpack
logger = create_logger()
# Does this version of llfuse support ns precision? # Does this version of llfuse support ns precision?
have_fuse_xtime_ns = hasattr(llfuse.EntryAttributes, 'st_mtime_ns') have_fuse_xtime_ns = hasattr(llfuse.EntryAttributes, 'st_mtime_ns')
@ -54,6 +58,9 @@ def __init__(self, key, repository, manifest, archive, cached_repo):
self.pending_archives = {} self.pending_archives = {}
self.accounted_chunks = {} self.accounted_chunks = {}
self.cache = ItemCache() self.cache = ItemCache()
data_cache_capacity = int(os.environ.get('BORG_MOUNT_DATA_CACHE_ENTRIES', os.cpu_count() or 1))
logger.debug('mount data cache capacity: %d chunks', data_cache_capacity)
self.data_cache = LRUCache(capacity=data_cache_capacity, dispose=lambda _: None)
if archive: if archive:
self.process_archive(archive) self.process_archive(archive)
else: else:
@ -229,7 +236,16 @@ def read(self, fh, offset, size):
offset -= s offset -= s
continue continue
n = min(size, s - offset) n = min(size, s - offset)
if id in self.data_cache:
data = self.data_cache[id]
if offset + n == len(data):
# evict fully read chunk from cache
del self.data_cache[id]
else:
_, data = self.key.decrypt(id, self.repository.get(id)) _, data = self.key.decrypt(id, self.repository.get(id))
if offset + n < len(data):
# chunk was only partially read, cache it
self.data_cache[id] = data
parts.append(data[offset:offset + n]) parts.append(data[offset:offset + n])
offset = 0 offset = 0
size -= n size -= n