1247644 - Instantly get rid of unreferenced and doomed HTTP cache entries

Status: RESOLVED FIXED

Description

[Honza Bambas (:mayhemer)]

+also drop any I/O on them (except closing/erasing a file when present and not after shutdown)

When CacheEntry::mHandlesCount == 0 && mIsDoomed -> tell the cache file to "kill" itself instantly (= no (meta)data writes, just wipe the file existence, if there has even been a file physically open).

Comment 1

[Honza Bambas (:mayhemer)]

The main motivation here is the Skype bug 1215970.  But according the most recent findings, this may not be an immediate problem, turning this bug to just a small optimization.

Comment 2

[Honza Bambas (:mayhemer)]

Tho... I can see this happening often enough to get my attention when scrolling timelines on facebook.  So, it may be worth doing.

Comment 3

[Honza Bambas (:mayhemer)]

Attachment: v1

- CacheFileIOListener has a new virtual getter IsKilled
- that one is reimplemented by CacheFile
- returns true after last outer reference to CacheEntry has been released and that entry has also been doomed
- most of the operations of IO manager check for this flag being set (on main thread and in *Internal parts, and if killed, open, truncate, read and write are completely bypassed
- cache file input stream now also keeps an outer reference to its cache entry so that we don't kill a file whom input stream is life

This saves doing IO (mainly early metadata write) on cache files that will never be used (are unreachable and doomed).


Among other patches:
https://treeherder.mozilla.org/#/jobs?repo=try&revision=ee1b8b5b1464

Comment 4

[Honza Bambas (:mayhemer)]

Better try run: https://treeherder.mozilla.org/#/jobs?repo=try&revision=8468c928d0e2

Comment 5

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/74c396a8252c

Comment 6

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/74c396a8252c