Disable event/eventopt if apr skiplist isn't available

Revert Paul's lock free circular queue changes done on MPM-event. The changes have been moved to branches/mpm-event-optimization. This puts trunk's MPM-event back to the state of 2.4.x, except for serf support. The following commits are reverted: ------------------------------------------------------------------------ r1203404 | trawick | 2011-11-17 23:48:35 +0100 event no longer requires APR_POLLSET_THREADSAFE, or any other non-standard feature (all but OS/2 have APR_POLLSET_WAKEABLE) config-foo: don't require thread-safe pollset in order to build event event.c: don't stress APR_ENOTIMPL in apr_pollset_create errors; just give the standard "check system or user limits" message ------------------------------------------------------------------------ r1203858 | trawick | 2011-11-18 22:39:33 +0100 follow up to r1202257 -- perform normal wakeup processing when APR_EINTR is seen from apr_pollset_poll(), with expectation that it was triggered by apr_pollset_wakeup() ------------------------------------------------------------------------ r1202395 | trawick | 2011-11-15 20:38:31 +0100 spellcheck r1202258 ------------------------------------------------------------------------ r1202329 | pquerna | 2011-11-15 18:47:33 +0100 Calculate the power of two size of the buffer before allocating it. Spotted by: Rüdiger Plüm ------------------------------------------------------------------------ r1202259 | pquerna | 2011-11-15 16:52:59 +0100 Use apr_pollset_wakeup to ensure that the listener thread will process most enqueue'd events quickly ------------------------------------------------------------------------ r1202258 | pquerna | 2011-11-15 16:52:00 +0100 Because the pollset is now only mutated from the event thread, we no longer need the APR_POLLSET_THREADSAFE flag for the event_pollset ------------------------------------------------------------------------ r1202257 | pquerna | 2011-11-15 16:51:03 +0100 Create a new lock free circular queue, and use it in the EventMPM to remove the timeout mutex that was wrapping both timeout queue operations and pollset operations. ------------------------------------------------------------------------ r1202256 | pquerna | 2011-11-15 16:50:09 +0100 Instead of disabling the listening sockets from the pollset when under load, just stop calling the accept call, but leave the sockets in the pollset.

event no longer requires APR_POLLSET_THREADSAFE, or any other non-standard feature (all but OS/2 have APR_POLLSET_WAKEABLE) config-foo: don't require thread-safe pollset in order to build event event.c: don't stress APR_ENOTIMPL in apr_pollset_create errors; just give the standard "check system or user limits" message

Improve hack to "determine" if APR supports thread-safe pollsets by hiding the presence of kqueue() on Leopard, matching APR's configuration. Event and Simple no longer report that they are supported on Leopard, resolving a broken default config file with --enable-mpms-shared=all on that platform. (Event was loaded by default in httpd.conf, and it failed at startup when it failed to obtain a thread-safe pollset.)

Move logic to decide if an MPM is supported, and whether the MPM is threaded, down to the MPM itself. (server/mpm/FOO/config.m4, which runs before the actual MPM selection) server/mpm/config.m4 makes some general platform checks that can be used for MPM decisions, and contains some functions related to MPMs. XXX The check here for whether APR_POLLSET_THREADSAFE is available is a rough approximation and needs to be replaced by a run-time check. Replace the limited per-platform hard-coded MPM selection and the current defaulting to event (whether or not it works) with a selection based on which MPMs work on the platform, as reported by the MPMs themselves. (config2.m4, which runs after the MPMs record whether they are supported) Order of preference: WinNT (mingw32 only) then Event then Worker then Prefork