They work like semaphores, except that they need explicit initialization
and can optionally be shared between processes.

This fixes a problem when a backend replies with 304 Not Modified
(after a http conditional request from varnish) and does not supply a
header that was duplicate in the cached object.

Before this patch, varnish would only supply (by copying from the
expired object) the first instance of a duplicate header.

This reverts commit e7779bcb.

Add "last updated" timestamp for backend health in varnishadm

OK'd by phk@.

Fixes #1883.

Spotted by Coverity

Fixes a bug where we wait for an event to fire on the backend socket
prior to passing the request body.

The VBT_Wait call is now handled in vbe_dir_finish.

Test case by thomaslc

Fixes: #1806

This reverts commit eaac258d.

The benefits in terms of readability are uncertain and YMMV, but
compilers seem to find it harder to optimize too:

   cmpl   $0x0,-0x205c(%rbp)
   sete   %al
   movzbl %al,%eax
   or     %rax,%rdx

Before the change it would translate to just:

   or     $0x1,%rax
   mov    %rax,%rdx

Spotted by @fgsch

This patch was created using Coccinelle and the following steps:

   $ cat >take.cocci <<EOF
   @@
   expression t, f;
   constant m;
   @@

   - AN(f);
   - t = *f;
   - *f = NULL;
   - CHECK_OBJ_NOTNULL(t, m);
   + TAKE_OBJ_NOTNULL(t, f, m);
   EOF
   $ spatch --sp-file take.cocci --dir . --in-place

There's a recurring pattern throughout the code base of taking over
a reference (by nulling the original) essentially when resources are
freed. Instead of repeating this anti dangling pointers measure, it
can be wrapped in a documenting utility macro.

They're part of the tree now.

With this you can also filter based on logexpect's vsl arguments.

Fixes #1869

Fixes #1876

during streaming delivery.

This will only happen if the object fills multiple storage segments,
ie: if backend sends using chunked encoding or if the object is
multiple times larger than ${fetch_maxchunksize}.

pattern in the body.

can be released after the iteration.

Implement the non-streaming case of final.

Generated using https://www.talater.com/open-source-templates/.

This really is the wrong way to go, generated files should not live
in the source tree. But lightening the load of phk is more important.