Introduce a check_config phase between pre_config and open_logs,

to allow modules to review interdependent configuration directive
values and adjust them while messages can still be logged to the
console.

The open_logs phase is already used somewhat for this purpose by
certain MPMs (winnt, prefork, worker, and event) but only by forcing
their functions ahead of the core ap_open_logs() function, and
since this phase runs after the ap_signal_server function during startup,
it can not be used to generate messages on the console when restarting.

Add the check_config phase to mod_info and mod_example.

Handle relevant MPM directives during this phase and format messages
for both the console and the error log, as appropriate.  Bounds and sanity
checks on the values of the MPM directives are handled in sequence in
this phase instead of in the various directive handling functions, since
those functions (e.g., set_max_clients()) may not be called at all if their
directives do not appear in the configuration files, and even if they
are called, there is no guarantee that this will occur in any particular
order.

Remove from the worker and event MPMs the code in the pre_config phase
that alters the configuration node tree by re-ordering ThreadsPerChild
ahead of MaxClients.  This code is effective but insufficient; for
example, if ServerLimit follows MaxClients, the test against server_limit
in set_max_clients() is invalid.  (In practice, this only results in
incorrect or absent warnings on the console, because server_limit is
set to its configured value when the main loop re-runs the configuration
process.)

Prevent ap_threads_per_child from exceeding thread_limit in the
winnt, worker, and event MPMs.  This situation could occur if
ThreadsPerChild was not specified in the configuration files and
ThreadLimit was set to a value smaller than DEFAULT_THREADS_PER_CHILD,
because set_threads_per_child() would never be called and therefore
its bounds check against thread_limit would not be performed.

Remove from the winnt, prefork, worker, and event MPMs the
changed_limit_at_restart flag.  Set the first_server_limit and
first_thread_limit values during the first execution of the check_config
function, and use them to detect changes to ServerLimit and ThreadLimit
across restarts and issue appropriately formatted warnings.  Remove the
comments about the error log being a "bit bucket"; this was true when
the code was originally committed in r92530 but that was due to a bug
fixed in r92769.

Be consistent about setting all MPM configuration directive values in the
pre_config phase.

Rephrase and reformat the console and log file messages relating to
MPM configuration directives to be consistent across all MPMs.  Use
briefer messages when logging to the error log than to the console.

Update miscellaneous stale comments and messages (e.g., reference to
daemons_min_free in worker and event MPMs, "prefork open_logs" in
winnt MPM, and StartServers in netware MPM).

The winnt, netware, beos, and mpmt_os2 MPMs should be tested by developers
with access to those platforms, especially the winnt MPM, which has
unique logic with respect to distinguishing between parent and child
processes during the configuration phases.

Update the English documentation for the worker MPM's ThreadsPerChild
directive, which no longer needs to precede other MPM directives in the
configuration files if it has a non-default value.  The German (.de) and
Japanese (.ja) translations should be updated by developers fluent in
those languages.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@431460 13f79535-47bb-0310-9956-ffa450edef68