/brz/remove-bazaar

To get this branch, use:
bzr branch http://gegoxaren.bato24.eu/bzr/brz/remove-bazaar

« back to all changes in this revision

Viewing changes to bzrlib/lockable_files.py

  • Committer: John Arbash Meinel
  • Date: 2009-09-09 18:52:56 UTC
  • mto: (4634.52.16 2.0)
  • mto: This revision was merged to the branch mainline in revision 4738.
  • Revision ID: john@arbash-meinel.com-20090909185256-rdaxy872xauoem46
https://launchpad.net/bugs/402623
Work around bug #402623 by allowing BTreeGraphIndex(...,unlimited_cache=True).

The basic issue is that the access pattern for chk pages is fully random,
because the keys are 'sha1' handles. As such, we have no locality of
reference, and downloading a large project over HTTP can cause us to
redownload all of the .cix pages multiple times. The bug report
noticed the pages getting downloaded 4-5 times.
This was causing a significant increase in the total bytes downloaded.
(For Launchpad, downloading the 10MB cix file 5 times was 50MB, out of
around 160MB total download.)

Show diffs side-by-side

added added

removed removed

Lines of Context:
bzrlib/lockable_files.py
14
14
# along with this program; if not, write to the Free Software
15
15
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
16
16
 
 
17
from cStringIO import StringIO
 
18
 
17
19
from bzrlib.lazy_import import lazy_import
18
20
lazy_import(globals(), """
19
21
import codecs
30
32
""")
31
33
 
32
34
from bzrlib.decorators import (
33
 
    only_raises,
 
35
    needs_read_lock,
 
36
    needs_write_lock,
 
37
    )
 
38
from bzrlib.symbol_versioning import (
 
39
    deprecated_in,
 
40
    deprecated_method,
34
41
    )
35
42
 
36
43
 
214
221
        """Setup a write transaction."""
215
222
        self._set_transaction(transactions.WriteTransaction())
216
223
 
217
 
    @only_raises(errors.LockNotHeld, errors.LockBroken)
218
224
    def unlock(self):
219
225
        if not self._lock_mode:
220
226
            return lock.cant_unlock_not_held(self)