We should queue bo tasks to avoid failing client requests
unnecessarily.

The detailed parameter description of the queue_limit was already
correct, improve the short one.

The nthr => wthread_min assertion could trigger if
wthread_min was changed after the first comparison.

Previously, after sending a thread to varnish heaven, the herder slept
for wthread_destroy_delay unconditionally. Instead, we now wait on the
cv so we get woken up in case we run dry during the delay.

This change is relevant proportionally to the value of
wthread_destroy_delay if the spread between thread_pool_min and
thread_pool_max is big and varnish is exposed to sudden traffic peaks.

IOW, it will probably be only relevant for high performance setups.

Also, we now sleep for thread_pool_timeout unless a shorter delay is
warranted. This will delay the effect of thread parameter changes for
up to thread_pool_timeout seconds unless the pool runs dry, in which
case they will become effective immediately.

doc-fixes #2129

For epoll, we tolerate spurious reports, for all other waiters
we assert.

fixes #2117

Conflicts:
	bin/varnishd/waiter/cache_waiter_epoll.c

Fixes #1899
Closes #2110

Ramp up from simple tokens to here documents.

Conflicts:
	doc/sphinx/reference/varnish-cli.rst

When checking the timestamps on deleting a session, allow up to
clock_step seconds error before bailing.

Fixes: #1874

This value is used in calculations that could reveal clock step,
specifying the amount of error we allow before panicking. It defaults
to a conservative 1 second.

Show both the real and the monotonic time in the panic output when the
panic is created. This is useful to have something to compare other
panic timestamps against.

The existing timestamp in the panic output is recorded by the
management process at the time of receiving the panic from the child
process. Due to processing and possible core dump creation, this time
isn't very useful for comparison purposes.

Spotted & prodded by: 	Hermunn
Closes: #2026

Use MGT_complain() to log any errors; we might have a better chance to
understand what's going in.

Fixes #2115.

When we renamed resp.msg to resp.reason to match RFC and VCL terminology
we forgot to rename its counterpart. Instead of renaming -msg to -reason
the former will instead become an alias of the latter. This way it can
be applied to older branches (modulus inline documentation).

(Backport of 2bbcde1d with the fix b698aec2 squashed in)

doc fixes #2107

Updated error message in MGT_Child_Cli_Fail to indicate that we
actually have sent the kill signal to the child process.

A new jail level, JAIL_MASTER_KILL, is introduced. The mgt process
takes this level before killing the child process.

Fixes: #2010

A new function, kill_child() is introduced, so that kill() is only
called from this function. This is a preparation of fixing the jail
implementation.

There seems to be an error in the varnish jail design, which makes the
mgt process uable to kill the child process. To confirm this, add some
error checking to the relevant code.

Related to: #2010

This test wasn't working as it was supposed to, and would cause the
forward links graph building of log transactions to fail. The fail was
soft, as the reverse mapping still succeeded creating the right
mapping.

Depending on when the local thread log buffer was flushed, the problem
would show as spurious "duplicate link" log records to be inserted.

Fixes: #1830

Fixes #2017.

With a bit of documentation to explain how to use the two new macros.

Closes #2054

This file will now contain legacy macros, that is to say shims to deal
with older platforms and macros for out-of-tree VMODs introduced with
Varnish 4.0.0-tp1.

These macros work well but their interfaces aren't ideal and they leave
too much autotools work to downstream VMOD maintainers. They have also
suffered a lack of maintenance, like this 3yo comment:

    # Uses internal function for now..

New macros will be introduced, but the current macros are left as-is and
VMOD maintainers won't be forced to upgrade their build system.

A previous backport, "Use "none" to disable authentication" did not
skip mgt_cli_secret(S_arg) when -S '' was used. This fixes the
problem, so that -S '' has the same behavior as before.

Related to #2025.

thanks to @dridi for the dictionary lookup

Maybe it's just my brain that is incapable of considering the
fact that a bit of macro-fillin may in fact be #if 0 - disabled
here, so this should hopefully help me (and others?) to not
spend more life time than absolutely necessary on feeling stupid.