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busy cache entry or to ditch it.

Ditch it as soon as we can, so we don't hold other clients on a busy objcore
longer than necessary.



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4222 d4fa192b-c00b-0410-8231-f00ffab90ce4

Fixes #549



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replace a half-baked one in vtc.c with it.



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4219 d4fa192b-c00b-0410-8231-f00ffab90ce4

expiry thread from moving objcores from one list to another.



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4218 d4fa192b-c00b-0410-8231-f00ffab90ce4

I can tell FlexeLint to ignore them.



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4217 d4fa192b-c00b-0410-8231-f00ffab90ce4

Add a parameter, so the worker thread gets forced to dump stats
into the global pool for every N requests it serves.

This should solve the problem where a wget(1) client does not
show up in the stats, until the session ends.



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4216 d4fa192b-c00b-0410-8231-f00ffab90ce4

Move most of the stat fields used in cache_center.c into the workers
private stats, hopefully reducing the lock contention and stats
precision at the same time.



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git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4213 d4fa192b-c00b-0410-8231-f00ffab90ce4

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The cruical difference is that we can remove from a VLIST without
having the head of the VLIST, which comes handy when expiring a
non-instantiated object from a -spersistent stevedore.

We flip the LRU list around, so that the frontmost element has not
been accessed for the longest time, and simulate tail-inserts by
putting a senteniel on the tail of the list.

Presently the senteniel is a full objcore, which is a non-issue with
few machines having more than a handful of stevedores, but once the
persistent stevedore moves to per-segment LRU lists, this needs to
be addressed, probably by wrapping the LRU linkage in a separate
structure.


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This allows us to put items on a blacklist for a specific backend based on
the response it gave us. The basic syntax is (vcl_fetch):

if (beresp.status == 500) {
	set beresp.saintmode = 20s;
	restart;
}

Health checks are modified accordingly, which means graced objects are used
if no healthy backends are left to try.

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and try to push objects away from the tail end so that the list
can be shortened.

It won't work if your bans contains any req.* tests, because the
lurker has no request to compare against.

By default the lurker is disabled, you enable it by setting the
'ban_lurker_sleep' parameter to the amount of time the lurker
should sleep between doing things.

If it cannot do anything, it always sleeps for a second.

NB: This feature is on probation, there is currently no guarantee
it will end up in a future varnish release, it depends on the
impact and usability.  Feedback much anticipated.


One of the quasi-nasty details of this feature, is the need to work
against the lock-order in cache_hash.c, see details in comments for
HSH_FindBan().




git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4206 d4fa192b-c00b-0410-8231-f00ffab90ce4

the reference.



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4205 d4fa192b-c00b-0410-8231-f00ffab90ce4

it was possible to have infinite recursion between vcl_error returning restart and cnt_recv calling vcl_error when you had too many restarts

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4204 d4fa192b-c00b-0410-8231-f00ffab90ce4

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4203 d4fa192b-c00b-0410-8231-f00ffab90ce4

very first functions ever written in Varnish.   Since I knew
that the file stevedore would always return the size you asked for,
or panic, I didn't bother to actually check how big the storage
segment he allocated was, I just knew it would be the right size.

Guess what, segments are finite size in the -spersistent stevedore
so you may in fact _not_ get what you ask for.

(Cue music: Theme Music from The Keystone Kops)

DuH!


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Don't explode manager if it gets overwritten.



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Add test-case for same.



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for expiry of non-instantiated objects from -spersistent



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first, so combine them into one and avoid the issue entirely.



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This is the number of good probes we pretend to have already seen when
we start up, in order to speed up getting healthy backends.

The default value is one less than the .threshold, so the backend
will be set healthy if it manages to respond correctly to the very 
first probe we send to it.

(A bit of this commit leaked in during r4184)



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