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  1. 24 Sep, 2007 5 commits
    • Cecilie Fritzvold's avatar
      Update random and round-robin backends to use the new convenience functions. · 515b37cd
      Cecilie Fritzvold authored 
      
git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@2008 d4fa192b-c00b-0410-8231-f00ffab90ce4
      515b37cd
    • Poul-Henning Kamp's avatar
      Add code to VCC to output an identifier for each simple backend which · 6eef6757
      Poul-Henning Kamp authored 
      varnishd can use to decide if a backend state can be shared between
multiple VCL programs.
 
Originally the idea was to calculate a strong hash over the tokens 
which define the backend.  

Considering the relatively short lengths of backend declarations
and the infrequency of comparisons, we have opted for an extremely
weak hash instead:  We simply output the space separted tokens as
a string.
 
The net change in code for simple backends is marginal, but for
complex backends this will be a lot simpler to implement.



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@2007 d4fa192b-c00b-0410-8231-f00ffab90ce4
      6eef6757
    • Poul-Henning Kamp's avatar
      Our first cut at a LRU processing contained a three way race and can · 17662d28
      Poul-Henning Kamp authored 
      cause Really Weird Problems if you really provoke it.

+++ Redo from start +++

LRU processing is only relevant for objects which are in the cache and
on the EXP binary heap so we merge the LRU functionality with the EXP
code in order to share locks and object reference counts.

Another thing we overlooked in the first implementation is that the VCL
callout for LRU should be able to examine the client information for
the session which tries to push stuff out, so that QoS/DoS issues can be
considered:

	sub vcl_dicard {
		if (client.bandwidth > 10 mb/s) {
			keep;
		}
	}

(which sort of indicates that "error" should be a legal action as well)

To enable this, pass the session into the stevedore when we try to
allocate space and temporarily substitute the target object for its
own object while we call vcl_discard().

The outcome of an attempt to make space can take three values, did,
didn't and couldn't.  In the latter case there is no point in trying
again and again, in particular if the cause is incurable, such as
the requested size being larger than the storage.   We still need to
handle failure to allocate storage for that case rather than core dump.

When looking for targets to nuke, we only consider objects on the
binheap which has reference count of 1, objects with higher reference
counts would not free space.

We take prospective targets off the binheap, but retain their
refcount, and tag them with a magic marker while we ponder their
destiny.

It is quite possible that another session could pick the object up
via the cache while we do so, and therefore attempts to update the
ttl or shift them in the lru chain must ignore objects which has
the magic marker.  If the object is kept, the updated ttl will
automatically take effect when we reinsert it in the binheap.



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@2006 d4fa192b-c00b-0410-8231-f00ffab90ce4
      17662d28
    • Poul-Henning Kamp's avatar
      Add a couple of statistics counters for LRU · f80b4251
      Poul-Henning Kamp authored 
      
git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@2005 d4fa192b-c00b-0410-8231-f00ffab90ce4
      f80b4251
    • Poul-Henning Kamp's avatar
      Fix a NULL pointer dereference which cannot currently happen. · 2f7fee5a
      Poul-Henning Kamp authored 
      
git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@2004 d4fa192b-c00b-0410-8231-f00ffab90ce4
      2f7fee5a
  3. 23 Sep, 2007 10 commits
  5. 21 Sep, 2007 5 commits
  7. 20 Sep, 2007 19 commits
  9. 18 Sep, 2007 1 commit