--- libev/ev.pod	2008/05/24 03:08:03	1.161
+++ libev/ev.pod	2008/10/21 20:52:30	1.197
@@ -4,63 +4,63 @@
 
 =head1 SYNOPSIS
 
-  #include <ev.h>
+   #include <ev.h>
 
 =head2 EXAMPLE PROGRAM
 
-  // a single header file is required
-  #include <ev.h>
+   // a single header file is required
+   #include <ev.h>
 
-  // every watcher type has its own typedef'd struct
-  // with the name ev_<type>
-  ev_io stdin_watcher;
-  ev_timer timeout_watcher;
-
-  // all watcher callbacks have a similar signature
-  // this callback is called when data is readable on stdin
-  static void
-  stdin_cb (EV_P_ struct ev_io *w, int revents)
-  {
-    puts ("stdin ready");
-    // for one-shot events, one must manually stop the watcher
-    // with its corresponding stop function.
-    ev_io_stop (EV_A_ w);
-
-    // this causes all nested ev_loop's to stop iterating
-    ev_unloop (EV_A_ EVUNLOOP_ALL);
-  }
-
-  // another callback, this time for a time-out
-  static void
-  timeout_cb (EV_P_ struct ev_timer *w, int revents)
-  {
-    puts ("timeout");
-    // this causes the innermost ev_loop to stop iterating
-    ev_unloop (EV_A_ EVUNLOOP_ONE);
-  }
-
-  int
-  main (void)
-  {
-    // use the default event loop unless you have special needs
-    struct ev_loop *loop = ev_default_loop (0);
-
-    // initialise an io watcher, then start it
-    // this one will watch for stdin to become readable
-    ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
-    ev_io_start (loop, &stdin_watcher);
-
-    // initialise a timer watcher, then start it
-    // simple non-repeating 5.5 second timeout
-    ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
-    ev_timer_start (loop, &timeout_watcher);
-
-    // now wait for events to arrive
-    ev_loop (loop, 0);
-
-    // unloop was called, so exit
-    return 0;
-  }
+   // every watcher type has its own typedef'd struct
+   // with the name ev_<type>
+   ev_io stdin_watcher;
+   ev_timer timeout_watcher;
+
+   // all watcher callbacks have a similar signature
+   // this callback is called when data is readable on stdin
+   static void
+   stdin_cb (EV_P_ struct ev_io *w, int revents)
+   {
+     puts ("stdin ready");
+     // for one-shot events, one must manually stop the watcher
+     // with its corresponding stop function.
+     ev_io_stop (EV_A_ w);
+
+     // this causes all nested ev_loop's to stop iterating
+     ev_unloop (EV_A_ EVUNLOOP_ALL);
+   }
+
+   // another callback, this time for a time-out
+   static void
+   timeout_cb (EV_P_ struct ev_timer *w, int revents)
+   {
+     puts ("timeout");
+     // this causes the innermost ev_loop to stop iterating
+     ev_unloop (EV_A_ EVUNLOOP_ONE);
+   }
+
+   int
+   main (void)
+   {
+     // use the default event loop unless you have special needs
+     struct ev_loop *loop = ev_default_loop (0);
+
+     // initialise an io watcher, then start it
+     // this one will watch for stdin to become readable
+     ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
+     ev_io_start (loop, &stdin_watcher);
+
+     // initialise a timer watcher, then start it
+     // simple non-repeating 5.5 second timeout
+     ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
+     ev_timer_start (loop, &timeout_watcher);
+
+     // now wait for events to arrive
+     ev_loop (loop, 0);
+
+     // unloop was called, so exit
+     return 0;
+   }
 
 =head1 DESCRIPTION
 
@@ -180,9 +180,9 @@
 Example: Make sure we haven't accidentally been linked against the wrong
 version.
 
-  assert (("libev version mismatch",
-           ev_version_major () == EV_VERSION_MAJOR
-           && ev_version_minor () >= EV_VERSION_MINOR));
+   assert (("libev version mismatch",
+            ev_version_major () == EV_VERSION_MAJOR
+            && ev_version_minor () >= EV_VERSION_MINOR));
 
 =item unsigned int ev_supported_backends ()
 
@@ -194,8 +194,8 @@
 Example: make sure we have the epoll method, because yeah this is cool and
 a must have and can we have a torrent of it please!!!11
 
-  assert (("sorry, no epoll, no sex",
-           ev_supported_backends () & EVBACKEND_EPOLL));
+   assert (("sorry, no epoll, no sex",
+            ev_supported_backends () & EVBACKEND_EPOLL));
 
 =item unsigned int ev_recommended_backends ()
 
@@ -216,7 +216,7 @@
 
 See the description of C<ev_embed> watchers for more info.
 
-=item ev_set_allocator (void *(*cb)(void *ptr, long size))
+=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]
 
 Sets the allocation function to use (the prototype is similar - the
 semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
@@ -252,7 +252,7 @@
    ...
    ev_set_allocator (persistent_realloc);
 
-=item ev_set_syserr_cb (void (*cb)(const char *msg));
+=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]
 
 Set the callback function to call on a retryable system call error (such
 as failed select, poll, epoll_wait). The message is a printable string
@@ -361,6 +361,10 @@
 a look at C<ev_set_io_collect_interval ()> to increase the amount of
 readiness notifications you get per iteration.
 
+This backend maps C<EV_READ> to the C<readfds> set and C<EV_WRITE> to the
+C<writefds> set (and to work around Microsoft Windows bugs, also onto the
+C<exceptfds> set on that platform).
+
 =item C<EVBACKEND_POLL>    (value 2, poll backend, available everywhere except on windows)
 
 And this is your standard poll(2) backend. It's more complicated
@@ -370,6 +374,9 @@
 i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for
 performance tips.
 
+This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and
+C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.
+
 =item C<EVBACKEND_EPOLL>   (value 4, Linux)
 
 For few fds, this backend is a bit little slower than poll and select,
@@ -391,21 +398,25 @@
 (or space) is available.
 
 Best performance from this backend is achieved by not unregistering all
-watchers for a file descriptor until it has been closed, if possible, i.e.
-keep at least one watcher active per fd at all times.
+watchers for a file descriptor until it has been closed, if possible,
+i.e. keep at least one watcher active per fd at all times. Stopping and
+starting a watcher (without re-setting it) also usually doesn't cause
+extra overhead.
 
 While nominally embeddable in other event loops, this feature is broken in
 all kernel versions tested so far.
 
+This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
+C<EVBACKEND_POLL>.
+
 =item C<EVBACKEND_KQUEUE>  (value 8, most BSD clones)
 
-Kqueue deserves special mention, as at the time of this writing, it
-was broken on all BSDs except NetBSD (usually it doesn't work reliably
-with anything but sockets and pipes, except on Darwin, where of course
-it's completely useless). For this reason it's not being "auto-detected"
-unless you explicitly specify it explicitly in the flags (i.e. using
-C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
-system like NetBSD.
+Kqueue deserves special mention, as at the time of this writing, it was
+broken on all BSDs except NetBSD (usually it doesn't work reliably with
+anything but sockets and pipes, except on Darwin, where of course it's
+completely useless). For this reason it's not being "auto-detected" unless
+you explicitly specify it in the flags (i.e. using C<EVBACKEND_KQUEUE>) or
+libev was compiled on a known-to-be-good (-enough) system like NetBSD.
 
 You still can embed kqueue into a normal poll or select backend and use it
 only for sockets (after having made sure that sockets work with kqueue on
@@ -415,7 +426,7 @@
 kernel is more efficient (which says nothing about its actual speed, of
 course). While stopping, setting and starting an I/O watcher does never
 cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
-two event changes per incident, support for C<fork ()> is very bad and it
+two event changes per incident. Support for C<fork ()> is very bad and it
 drops fds silently in similarly hard-to-detect cases.
 
 This backend usually performs well under most conditions.
@@ -424,8 +435,12 @@
 everywhere, so you might need to test for this. And since it is broken
 almost everywhere, you should only use it when you have a lot of sockets
 (for which it usually works), by embedding it into another event loop
-(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for
-sockets.
+(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and, did I mention it,
+using it only for sockets.
+
+This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with
+C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with
+C<NOTE_EOF>.
 
 =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
 
@@ -448,9 +463,13 @@
 descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
 might perform better.
 
-On the positive side, ignoring the spurious readiness notifications, this
-backend actually performed to specification in all tests and is fully
-embeddable, which is a rare feat among the OS-specific backends.
+On the positive side, with the exception of the spurious readiness
+notifications, this backend actually performed fully to specification
+in all tests and is fully embeddable, which is a rare feat among the
+OS-specific backends.
+
+This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
+C<EVBACKEND_POLL>.
 
 =item C<EVBACKEND_ALL>
 
@@ -466,21 +485,22 @@
 backends will be tried (in the reverse order as listed here). If none are
 specified, all backends in C<ev_recommended_backends ()> will be tried.
 
-The most typical usage is like this:
+Example: This is the most typical usage.
 
-  if (!ev_default_loop (0))
-    fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
+   if (!ev_default_loop (0))
+     fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
 
-Restrict libev to the select and poll backends, and do not allow
+Example: Restrict libev to the select and poll backends, and do not allow
 environment settings to be taken into account:
 
-  ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
+   ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
 
-Use whatever libev has to offer, but make sure that kqueue is used if
-available (warning, breaks stuff, best use only with your own private
-event loop and only if you know the OS supports your types of fds):
+Example: Use whatever libev has to offer, but make sure that kqueue is
+used if available (warning, breaks stuff, best use only with your own
+private event loop and only if you know the OS supports your types of
+fds):
 
-  ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
+   ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
 
 =item struct ev_loop *ev_loop_new (unsigned int flags)
 
@@ -495,9 +515,9 @@
 
 Example: Try to create a event loop that uses epoll and nothing else.
 
-  struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
-  if (!epoller)
-    fatal ("no epoll found here, maybe it hides under your chair");
+   struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
+   if (!epoller)
+     fatal ("no epoll found here, maybe it hides under your chair");
 
 =item ev_default_destroy ()
 
@@ -546,11 +566,13 @@
 
 Like C<ev_default_fork>, but acts on an event loop created by
 C<ev_loop_new>. Yes, you have to call this on every allocated event loop
-after fork, and how you do this is entirely your own problem.
+after fork that you want to re-use in the child, and how you do this is
+entirely your own problem.
 
 =item int ev_is_default_loop (loop)
 
-Returns true when the given loop actually is the default loop, false otherwise.
+Returns true when the given loop is, in fact, the default loop, and false
+otherwise.
 
 =item unsigned int ev_loop_count (loop)
 
@@ -575,6 +597,18 @@
 time used for relative timers. You can treat it as the timestamp of the
 event occurring (or more correctly, libev finding out about it).
 
+=item ev_now_update (loop)
+
+Establishes the current time by querying the kernel, updating the time
+returned by C<ev_now ()> in the progress. This is a costly operation and
+is usually done automatically within C<ev_loop ()>.
+
+This function is rarely useful, but when some event callback runs for a
+very long time without entering the event loop, updating libev's idea of
+the current time is a good idea.
+
+See also "The special problem of time updates" in the C<ev_timer> section.
+
 =item ev_loop (loop, int flags)
 
 Finally, this is it, the event handler. This function usually is called
@@ -586,41 +620,48 @@
 
 Please note that an explicit C<ev_unloop> is usually better than
 relying on all watchers to be stopped when deciding when a program has
-finished (especially in interactive programs), but having a program that
-automatically loops as long as it has to and no longer by virtue of
-relying on its watchers stopping correctly is a thing of beauty.
+finished (especially in interactive programs), but having a program
+that automatically loops as long as it has to and no longer by virtue
+of relying on its watchers stopping correctly, that is truly a thing of
+beauty.
 
 A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle
-those events and any outstanding ones, but will not block your process in
-case there are no events and will return after one iteration of the loop.
+those events and any already outstanding ones, but will not block your
+process in case there are no events and will return after one iteration of
+the loop.
 
 A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
-necessary) and will handle those and any outstanding ones. It will block
-your process until at least one new event arrives, and will return after
-one iteration of the loop. This is useful if you are waiting for some
-external event in conjunction with something not expressible using other
-libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
+necessary) and will handle those and any already outstanding ones. It
+will block your process until at least one new event arrives (which could
+be an event internal to libev itself, so there is no guarentee that a
+user-registered callback will be called), and will return after one
+iteration of the loop.
+
+This is useful if you are waiting for some external event in conjunction
+with something not expressible using other libev watchers (i.e. "roll your
+own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
 usually a better approach for this kind of thing.
 
 Here are the gory details of what C<ev_loop> does:
 
    - Before the first iteration, call any pending watchers.
    * If EVFLAG_FORKCHECK was used, check for a fork.
-   - If a fork was detected, queue and call all fork watchers.
+   - If a fork was detected (by any means), queue and call all fork watchers.
    - Queue and call all prepare watchers.
-   - If we have been forked, recreate the kernel state.
+   - If we have been forked, detach and recreate the kernel state
+     as to not disturb the other process.
    - Update the kernel state with all outstanding changes.
-   - Update the "event loop time".
+   - Update the "event loop time" (ev_now ()).
    - Calculate for how long to sleep or block, if at all
      (active idle watchers, EVLOOP_NONBLOCK or not having
      any active watchers at all will result in not sleeping).
    - Sleep if the I/O and timer collect interval say so.
    - Block the process, waiting for any events.
    - Queue all outstanding I/O (fd) events.
-   - Update the "event loop time" and do time jump handling.
-   - Queue all outstanding timers.
-   - Queue all outstanding periodics.
-   - If no events are pending now, queue all idle watchers.
+   - Update the "event loop time" (ev_now ()), and do time jump adjustments.
+   - Queue all expired timers.
+   - Queue all expired periodics.
+   - Unless any events are pending now, queue all idle watchers.
    - Queue all check watchers.
    - Call all queued watchers in reverse order (i.e. check watchers first).
      Signals and child watchers are implemented as I/O watchers, and will
@@ -635,7 +676,7 @@
    ... queue jobs here, make sure they register event watchers as long
    ... as they still have work to do (even an idle watcher will do..)
    ev_loop (my_loop, 0);
-   ... jobs done. yeah!
+   ... jobs done or somebody called unloop. yeah!
 
 =item ev_unloop (loop, how)
 
@@ -646,18 +687,23 @@
 
 This "unloop state" will be cleared when entering C<ev_loop> again.
 
+It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.
+
 =item ev_ref (loop)
 
 =item ev_unref (loop)
 
 Ref/unref can be used to add or remove a reference count on the event
 loop: Every watcher keeps one reference, and as long as the reference
-count is nonzero, C<ev_loop> will not return on its own. If you have
-a watcher you never unregister that should not keep C<ev_loop> from
-returning, ev_unref() after starting, and ev_ref() before stopping it. For
-example, libev itself uses this for its internal signal pipe: It is not
-visible to the libev user and should not keep C<ev_loop> from exiting if
-no event watchers registered by it are active. It is also an excellent
+count is nonzero, C<ev_loop> will not return on its own.
+
+If you have a watcher you never unregister that should not keep C<ev_loop>
+from returning, call ev_unref() after starting, and ev_ref() before
+stopping it.
+
+As an example, libev itself uses this for its internal signal pipe: It is
+not visible to the libev user and should not keep C<ev_loop> from exiting
+if no event watchers registered by it are active. It is also an excellent
 way to do this for generic recurring timers or from within third-party
 libraries. Just remember to I<unref after start> and I<ref before stop>
 (but only if the watcher wasn't active before, or was active before,
@@ -666,31 +712,33 @@
 Example: Create a signal watcher, but keep it from keeping C<ev_loop>
 running when nothing else is active.
 
-  struct ev_signal exitsig;
-  ev_signal_init (&exitsig, sig_cb, SIGINT);
-  ev_signal_start (loop, &exitsig);
-  evf_unref (loop);
+   struct ev_signal exitsig;
+   ev_signal_init (&exitsig, sig_cb, SIGINT);
+   ev_signal_start (loop, &exitsig);
+   evf_unref (loop);
 
 Example: For some weird reason, unregister the above signal handler again.
 
-  ev_ref (loop);
-  ev_signal_stop (loop, &exitsig);
+   ev_ref (loop);
+   ev_signal_stop (loop, &exitsig);
 
 =item ev_set_io_collect_interval (loop, ev_tstamp interval)
 
 =item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
 
 These advanced functions influence the time that libev will spend waiting
-for events. Both are by default C<0>, meaning that libev will try to
-invoke timer/periodic callbacks and I/O callbacks with minimum latency.
+for events. Both time intervals are by default C<0>, meaning that libev
+will try to invoke timer/periodic callbacks and I/O callbacks with minimum
+latency.
 
 Setting these to a higher value (the C<interval> I<must> be >= C<0>)
-allows libev to delay invocation of I/O and timer/periodic callbacks to
-increase efficiency of loop iterations.
-
-The background is that sometimes your program runs just fast enough to
-handle one (or very few) event(s) per loop iteration. While this makes
-the program responsive, it also wastes a lot of CPU time to poll for new
+allows libev to delay invocation of I/O and timer/periodic callbacks
+to increase efficiency of loop iterations (or to increase power-saving
+opportunities).
+
+The idea is that sometimes your program runs just fast enough to handle
+one (or very few) event(s) per loop iteration. While this makes the
+program responsive, it also wastes a lot of CPU time to poll for new
 events, especially with backends like C<select ()> which have a high
 overhead for the actual polling but can deliver many events at once.
 
@@ -702,9 +750,9 @@
 
 Likewise, by setting a higher I<timeout collect interval> you allow libev
 to spend more time collecting timeouts, at the expense of increased
-latency (the watcher callback will be called later). C<ev_io> watchers
-will not be affected. Setting this to a non-null value will not introduce
-any overhead in libev.
+latency/jitter/inexactness (the watcher callback will be called
+later). C<ev_io> watchers will not be affected. Setting this to a non-null
+value will not introduce any overhead in libev.
 
 Many (busy) programs can usually benefit by setting the I/O collect
 interval to a value near C<0.1> or so, which is often enough for
@@ -712,12 +760,20 @@
 usually doesn't make much sense to set it to a lower value than C<0.01>,
 as this approaches the timing granularity of most systems.
 
+Setting the I<timeout collect interval> can improve the opportunity for
+saving power, as the program will "bundle" timer callback invocations that
+are "near" in time together, by delaying some, thus reducing the number of
+times the process sleeps and wakes up again. Another useful technique to
+reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
+they fire on, say, one-second boundaries only.
+
 =item ev_loop_verify (loop)
 
 This function only does something when C<EV_VERIFY> support has been
-compiled in. It tries to go through all internal structures and checks
-them for validity. If anything is found to be inconsistent, it will print
-an error message to standard error and call C<abort ()>.
+compiled in. which is the default for non-minimal builds. It tries to go
+through all internal structures and checks them for validity. If anything
+is found to be inconsistent, it will print an error message to standard
+error and call C<abort ()>.
 
 This can be used to catch bugs inside libev itself: under normal
 circumstances, this function will never abort as of course libev keeps its
@@ -732,18 +788,18 @@
 interest in some event. For instance, if you want to wait for STDIN to
 become readable, you would create an C<ev_io> watcher for that:
 
-  static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
-  {
-    ev_io_stop (w);
-    ev_unloop (loop, EVUNLOOP_ALL);
-  }
-
-  struct ev_loop *loop = ev_default_loop (0);
-  struct ev_io stdin_watcher;
-  ev_init (&stdin_watcher, my_cb);
-  ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
-  ev_io_start (loop, &stdin_watcher);
-  ev_loop (loop, 0);
+   static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
+   {
+     ev_io_stop (w);
+     ev_unloop (loop, EVUNLOOP_ALL);
+   }
+
+   struct ev_loop *loop = ev_default_loop (0);
+   struct ev_io stdin_watcher;
+   ev_init (&stdin_watcher, my_cb);
+   ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
+   ev_io_start (loop, &stdin_watcher);
+   ev_loop (loop, 0);
 
 As you can see, you are responsible for allocating the memory for your
 watcher structures (and it is usually a bad idea to do this on the stack,
@@ -840,14 +896,19 @@
 An unspecified error has occurred, the watcher has been stopped. This might
 happen because the watcher could not be properly started because libev
 ran out of memory, a file descriptor was found to be closed or any other
-problem. You best act on it by reporting the problem and somehow coping
-with the watcher being stopped.
+problem. Libev considers these application bugs.
 
-Libev will usually signal a few "dummy" events together with an error,
-for example it might indicate that a fd is readable or writable, and if
-your callbacks is well-written it can just attempt the operation and cope
-with the error from read() or write(). This will not work in multi-threaded
-programs, though, so beware.
+You best act on it by reporting the problem and somehow coping with the
+watcher being stopped. Note that well-written programs should not receive
+an error ever, so when your watcher receives it, this usually indicates a
+bug in your program.
+
+Libev will usually signal a few "dummy" events together with an error, for
+example it might indicate that a fd is readable or writable, and if your
+callbacks is well-written it can just attempt the operation and cope with
+the error from read() or write(). This will not work in multi-threaded
+programs, though, as the fd could already be closed and reused for another
+thing, so beware.
 
 =back
 
@@ -873,6 +934,12 @@
 The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher,
 int revents)>.
 
+Example: Initialise an C<ev_io> watcher in two steps.
+
+   ev_io w;
+   ev_init (&w, my_cb);
+   ev_io_set (&w, STDIN_FILENO, EV_READ);
+
 =item C<ev_TYPE_set> (ev_TYPE *, [args])
 
 This macro initialises the type-specific parts of a watcher. You need to
@@ -884,25 +951,38 @@
 Although some watcher types do not have type-specific arguments
 (e.g. C<ev_prepare>) you still need to call its C<set> macro.
 
+See C<ev_init>, above, for an example.
+
 =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
 
 This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
 calls into a single call. This is the most convenient method to initialise
 a watcher. The same limitations apply, of course.
 
+Example: Initialise and set an C<ev_io> watcher in one step.
+
+   ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
+
 =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
 
 Starts (activates) the given watcher. Only active watchers will receive
 events. If the watcher is already active nothing will happen.
 
+Example: Start the C<ev_io> watcher that is being abused as example in this
+whole section.
+
+   ev_io_start (EV_DEFAULT_UC, &w);
+
 =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)
 
-Stops the given watcher again (if active) and clears the pending
-status. It is possible that stopped watchers are pending (for example,
-non-repeating timers are being stopped when they become pending), but
-C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If
-you want to free or reuse the memory used by the watcher it is therefore a
-good idea to always call its C<ev_TYPE_stop> function.
+Stops the given watcher if active, and clears the pending status (whether
+the watcher was active or not).
+
+It is possible that stopped watchers are pending - for example,
+non-repeating timers are being stopped when they become pending - but
+calling C<ev_TYPE_stop> ensures that the watcher is neither active nor
+pending. If you want to free or reuse the memory used by the watcher it is
+therefore a good idea to always call its C<ev_TYPE_stop> function.
 
 =item bool ev_is_active (ev_TYPE *watcher)
 
@@ -960,74 +1040,85 @@
 
 Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
 C<loop> nor C<revents> need to be valid as long as the watcher callback
-can deal with that fact.
+can deal with that fact, as both are simply passed through to the
+callback.
 
 =item int ev_clear_pending (loop, ev_TYPE *watcher)
 
-If the watcher is pending, this function returns clears its pending status
-and returns its C<revents> bitset (as if its callback was invoked). If the
+If the watcher is pending, this function clears its pending status and
+returns its C<revents> bitset (as if its callback was invoked). If the
 watcher isn't pending it does nothing and returns C<0>.
 
+Sometimes it can be useful to "poll" a watcher instead of waiting for its
+callback to be invoked, which can be accomplished with this function.
+
 =back
 
 
 =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
 
 Each watcher has, by default, a member C<void *data> that you can change
-and read at any time, libev will completely ignore it. This can be used
+and read at any time: libev will completely ignore it. This can be used
 to associate arbitrary data with your watcher. If you need more data and
 don't want to allocate memory and store a pointer to it in that data
 member, you can also "subclass" the watcher type and provide your own
 data:
 
-  struct my_io
-  {
-    struct ev_io io;
-    int otherfd;
-    void *somedata;
-    struct whatever *mostinteresting;
-  }
+   struct my_io
+   {
+     struct ev_io io;
+     int otherfd;
+     void *somedata;
+     struct whatever *mostinteresting;
+   };
+
+   ...
+   struct my_io w;
+   ev_io_init (&w.io, my_cb, fd, EV_READ);
 
 And since your callback will be called with a pointer to the watcher, you
 can cast it back to your own type:
 
-  static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
-  {
-    struct my_io *w = (struct my_io *)w_;
-    ...
-  }
+   static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
+   {
+     struct my_io *w = (struct my_io *)w_;
+     ...
+   }
 
 More interesting and less C-conformant ways of casting your callback type
 instead have been omitted.
 
-Another common scenario is having some data structure with multiple
-watchers:
+Another common scenario is to use some data structure with multiple
+embedded watchers:
 
-  struct my_biggy
-  {
-    int some_data;
-    ev_timer t1;
-    ev_timer t2;
-  }
-
-In this case getting the pointer to C<my_biggy> is a bit more complicated,
-you need to use C<offsetof>:
-
-  #include <stddef.h>
-
-  static void
-  t1_cb (EV_P_ struct ev_timer *w, int revents)
-  {
-    struct my_biggy big = (struct my_biggy *
-      (((char *)w) - offsetof (struct my_biggy, t1));
-  }
-
-  static void
-  t2_cb (EV_P_ struct ev_timer *w, int revents)
-  {
-    struct my_biggy big = (struct my_biggy *
-      (((char *)w) - offsetof (struct my_biggy, t2));
-  }
+   struct my_biggy
+   {
+     int some_data;
+     ev_timer t1;
+     ev_timer t2;
+   }
+
+In this case getting the pointer to C<my_biggy> is a bit more
+complicated: Either you store the address of your C<my_biggy> struct
+in the C<data> member of the watcher (for woozies), or you need to use
+some pointer arithmetic using C<offsetof> inside your watchers (for real
+programmers):
+
+   #include <stddef.h>
+
+   static void
+   t1_cb (EV_P_ struct ev_timer *w, int revents)
+   {
+     struct my_biggy big = (struct my_biggy *
+       (((char *)w) - offsetof (struct my_biggy, t1));
+   }
+
+   static void
+   t2_cb (EV_P_ struct ev_timer *w, int revents)
+   {
+     struct my_biggy big = (struct my_biggy *
+       (((char *)w) - offsetof (struct my_biggy, t2));
+   }
 
 
 =head1 WATCHER TYPES
@@ -1061,9 +1152,9 @@
 descriptors to non-blocking mode is also usually a good idea (but not
 required if you know what you are doing).
 
-If you must do this, then force the use of a known-to-be-good backend
-(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
-C<EVBACKEND_POLL>).
+If you cannot use non-blocking mode, then force the use of a
+known-to-be-good backend (at the time of this writing, this includes only
+C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>).
 
 Another thing you have to watch out for is that it is quite easy to
 receive "spurious" readiness notifications, that is your callback might
@@ -1074,17 +1165,21 @@
 it is best to always use non-blocking I/O: An extra C<read>(2) returning
 C<EAGAIN> is far preferable to a program hanging until some data arrives.
 
-If you cannot run the fd in non-blocking mode (for example you should not
-play around with an Xlib connection), then you have to separately re-test
-whether a file descriptor is really ready with a known-to-be good interface
-such as poll (fortunately in our Xlib example, Xlib already does this on
-its own, so its quite safe to use).
+If you cannot run the fd in non-blocking mode (for example you should
+not play around with an Xlib connection), then you have to separately
+re-test whether a file descriptor is really ready with a known-to-be good
+interface such as poll (fortunately in our Xlib example, Xlib already
+does this on its own, so its quite safe to use). Some people additionally
+use C<SIGALRM> and an interval timer, just to be sure you won't block
+indefinitely.
+
+But really, best use non-blocking mode.
 
 =head3 The special problem of disappearing file descriptors
 
 Some backends (e.g. kqueue, epoll) need to be told about closing a file
-descriptor (either by calling C<close> explicitly or by any other means,
-such as C<dup>). The reason is that you register interest in some file
+descriptor (either due to calling C<close> explicitly or any other means,
+such as C<dup2>). The reason is that you register interest in some file
 descriptor, but when it goes away, the operating system will silently drop
 this interest. If another file descriptor with the same number then is
 registered with libev, there is no efficient way to see that this is, in
@@ -1125,11 +1220,10 @@
 
 =head3 The special problem of SIGPIPE
 
-While not really specific to libev, it is easy to forget about SIGPIPE:
-when reading from a pipe whose other end has been closed, your program
-gets send a SIGPIPE, which, by default, aborts your program. For most
-programs this is sensible behaviour, for daemons, this is usually
-undesirable.
+While not really specific to libev, it is easy to forget about C<SIGPIPE>:
+when writing to a pipe whose other end has been closed, your program gets
+sent a SIGPIPE, which, by default, aborts your program. For most programs
+this is sensible behaviour, for daemons, this is usually undesirable.
 
 So when you encounter spurious, unexplained daemon exits, make sure you
 ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
@@ -1145,8 +1239,8 @@
 =item ev_io_set (ev_io *, int fd, int events)
 
 Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
-receive events for and events is either C<EV_READ>, C<EV_WRITE> or
-C<EV_READ | EV_WRITE> to receive the given events.
+receive events for and C<events> is either C<EV_READ>, C<EV_WRITE> or
+C<EV_READ | EV_WRITE>, to express the desire to receive the given events.
 
 =item int fd [read-only]
 
@@ -1164,19 +1258,19 @@
 readable, but only once. Since it is likely line-buffered, you could
 attempt to read a whole line in the callback.
 
-  static void
-  stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
-  {
-     ev_io_stop (loop, w);
-    .. read from stdin here (or from w->fd) and haqndle any I/O errors
-  }
-
-  ...
-  struct ev_loop *loop = ev_default_init (0);
-  struct ev_io stdin_readable;
-  ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
-  ev_io_start (loop, &stdin_readable);
-  ev_loop (loop, 0);
+   static void
+   stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
+   {
+      ev_io_stop (loop, w);
+     .. read from stdin here (or from w->fd) and handle any I/O errors
+   }
+
+   ...
+   struct ev_loop *loop = ev_default_init (0);
+   struct ev_io stdin_readable;
+   ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
+   ev_io_start (loop, &stdin_readable);
+   ev_loop (loop, 0);
 
 
 =head2 C<ev_timer> - relative and optionally repeating timeouts
@@ -1186,21 +1280,33 @@
 
 The timers are based on real time, that is, if you register an event that
 times out after an hour and you reset your system clock to January last
-year, it will still time out after (roughly) and hour. "Roughly" because
+year, it will still time out after (roughly) one hour. "Roughly" because
 detecting time jumps is hard, and some inaccuracies are unavoidable (the
 monotonic clock option helps a lot here).
 
+The callback is guaranteed to be invoked only I<after> its timeout has
+passed, but if multiple timers become ready during the same loop iteration
+then order of execution is undefined.
+
+=head3 The special problem of time updates
+
+Establishing the current time is a costly operation (it usually takes at
+least two system calls): EV therefore updates its idea of the current
+time only before and after C<ev_loop> collects new events, which causes a
+growing difference between C<ev_now ()> and C<ev_time ()> when handling
+lots of events in one iteration.
+
 The relative timeouts are calculated relative to the C<ev_now ()>
 time. This is usually the right thing as this timestamp refers to the time
 of the event triggering whatever timeout you are modifying/starting. If
-you suspect event processing to be delayed and you I<need> to base the timeout
-on the current time, use something like this to adjust for this:
+you suspect event processing to be delayed and you I<need> to base the
+timeout on the current time, use something like this to adjust for this:
 
    ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
 
-The callback is guaranteed to be invoked only after its timeout has passed,
-but if multiple timers become ready during the same loop iteration then
-order of execution is undefined.
+If the event loop is suspended for a long time, you can also force an
+update of the time returned by C<ev_now ()> by calling C<ev_now_update
+()>.
 
 =head3 Watcher-Specific Functions and Data Members
 
@@ -1259,10 +1365,16 @@
 This is more slightly efficient then stopping/starting the timer each time
 you want to modify its timeout value.
 
+Note, however, that it is often even more efficient to remember the
+time of the last activity and let the timer time-out naturally. In the
+callback, you then check whether the time-out is real, or, if there was
+some activity, you reschedule the watcher to time-out in "last_activity +
+timeout - ev_now ()" seconds.
+
 =item ev_tstamp repeat [read-write]
 
 The current C<repeat> value. Will be used each time the watcher times out
-or C<ev_timer_again> is called and determines the next timeout (if any),
+or C<ev_timer_again> is called, and determines the next timeout (if any),
 which is also when any modifications are taken into account.
 
 =back
@@ -1271,33 +1383,33 @@
 
 Example: Create a timer that fires after 60 seconds.
 
-  static void
-  one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
-  {
-    .. one minute over, w is actually stopped right here
-  }
-
-  struct ev_timer mytimer;
-  ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
-  ev_timer_start (loop, &mytimer);
+   static void
+   one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
+   {
+     .. one minute over, w is actually stopped right here
+   }
+
+   struct ev_timer mytimer;
+   ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
+   ev_timer_start (loop, &mytimer);
 
 Example: Create a timeout timer that times out after 10 seconds of
 inactivity.
 
-  static void
-  timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
-  {
-    .. ten seconds without any activity
-  }
-
-  struct ev_timer mytimer;
-  ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
-  ev_timer_again (&mytimer); /* start timer */
-  ev_loop (loop, 0);
-
-  // and in some piece of code that gets executed on any "activity":
-  // reset the timeout to start ticking again at 10 seconds
-  ev_timer_again (&mytimer);
+   static void
+   timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
+   {
+     .. ten seconds without any activity
+   }
+
+   struct ev_timer mytimer;
+   ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
+   ev_timer_again (&mytimer); /* start timer */
+   ev_loop (loop, 0);
+
+   // and in some piece of code that gets executed on any "activity":
+   // reset the timeout to start ticking again at 10 seconds
+   ev_timer_again (&mytimer);
 
 
 =head2 C<ev_periodic> - to cron or not to cron?
@@ -1316,11 +1428,11 @@
 
 C<ev_periodic>s can also be used to implement vastly more complex timers,
 such as triggering an event on each "midnight, local time", or other
-complicated, rules.
+complicated rules.
 
 As with timers, the callback is guaranteed to be invoked only when the
 time (C<at>) has passed, but if multiple periodic timers become ready
-during the same loop iteration then order of execution is undefined.
+during the same loop iteration, then order of execution is undefined.
 
 =head3 Watcher-Specific Functions and Data Members
 
@@ -1331,16 +1443,16 @@
 =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
 
 Lots of arguments, lets sort it out... There are basically three modes of
-operation, and we will explain them from simplest to complex:
+operation, and we will explain them from simplest to most complex:
 
 =over 4
 
 =item * absolute timer (at = time, interval = reschedule_cb = 0)
 
 In this configuration the watcher triggers an event after the wall clock
-time C<at> has passed and doesn't repeat. It will not adjust when a time
+time C<at> has passed. It will not repeat and will not adjust when a time
 jump occurs, that is, if it is to be run at January 1st 2011 then it will
-run when the system time reaches or surpasses this time.
+only run when the system clock reaches or surpasses this time.
 
 =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
 
@@ -1348,9 +1460,9 @@
 C<at + N * interval> time (for some integer N, which can also be negative)
 and then repeat, regardless of any time jumps.
 
-This can be used to create timers that do not drift with respect to system
-time, for example, here is a C<ev_periodic> that triggers each hour, on
-the hour:
+This can be used to create timers that do not drift with respect to the
+system clock, for example, here is a C<ev_periodic> that triggers each
+hour, on the hour:
 
    ev_periodic_set (&periodic, 0., 3600., 0);
 
@@ -1447,37 +1559,37 @@
 =head3 Examples
 
 Example: Call a callback every hour, or, more precisely, whenever the
-system clock is divisible by 3600. The callback invocation times have
+system time is divisible by 3600. The callback invocation times have
 potentially a lot of jitter, but good long-term stability.
 
-  static void
-  clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
-  {
-    ... its now a full hour (UTC, or TAI or whatever your clock follows)
-  }
-
-  struct ev_periodic hourly_tick;
-  ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
-  ev_periodic_start (loop, &hourly_tick);
+   static void
+   clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
+   {
+     ... its now a full hour (UTC, or TAI or whatever your clock follows)
+   }
+
+   struct ev_periodic hourly_tick;
+   ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
+   ev_periodic_start (loop, &hourly_tick);
 
 Example: The same as above, but use a reschedule callback to do it:
 
-  #include <math.h>
+   #include <math.h>
 
-  static ev_tstamp
-  my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
-  {
-    return fmod (now, 3600.) + 3600.;
-  }
+   static ev_tstamp
+   my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
+   {
+     return now + (3600. - fmod (now, 3600.));
+   }
 
-  ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
+   ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
 
 Example: Call a callback every hour, starting now:
 
-  struct ev_periodic hourly_tick;
-  ev_periodic_init (&hourly_tick, clock_cb,
-                    fmod (ev_now (loop), 3600.), 3600., 0);
-  ev_periodic_start (loop, &hourly_tick);
+   struct ev_periodic hourly_tick;
+   ev_periodic_init (&hourly_tick, clock_cb,
+                     fmod (ev_now (loop), 3600.), 3600., 0);
+   ev_periodic_start (loop, &hourly_tick);
   
 
 =head2 C<ev_signal> - signal me when a signal gets signalled!
@@ -1487,12 +1599,16 @@
 will try it's best to deliver signals synchronously, i.e. as part of the
 normal event processing, like any other event.
 
+If you want signals asynchronously, just use C<sigaction> as you would
+do without libev and forget about sharing the signal. You can even use
+C<ev_async> from a signal handler to synchronously wake up an event loop.
+
 You can configure as many watchers as you like per signal. Only when the
-first watcher gets started will libev actually register a signal watcher
-with the kernel (thus it coexists with your own signal handlers as long
-as you don't register any with libev). Similarly, when the last signal
-watcher for a signal is stopped libev will reset the signal handler to
-SIG_DFL (regardless of what it was set to before).
+first watcher gets started will libev actually register a signal handler
+with the kernel (thus it coexists with your own signal handlers as long as
+you don't register any with libev for the same signal). Similarly, when
+the last signal watcher for a signal is stopped, libev will reset the
+signal handler to SIG_DFL (regardless of what it was set to before).
 
 If possible and supported, libev will install its handlers with
 C<SA_RESTART> behaviour enabled, so system calls should not be unduly
@@ -1519,26 +1635,29 @@
 
 =head3 Examples
 
-Example: Try to exit cleanly on SIGINT and SIGTERM.
+Example: Try to exit cleanly on SIGINT.
 
-  static void
-  sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
-  {
-    ev_unloop (loop, EVUNLOOP_ALL);
-  }
-
-  struct ev_signal signal_watcher;
-  ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
-  ev_signal_start (loop, &sigint_cb);
+   static void
+   sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
+   {
+     ev_unloop (loop, EVUNLOOP_ALL);
+   }
+
+   struct ev_signal signal_watcher;
+   ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
+   ev_signal_start (loop, &signal_watcher);
 
 
 =head2 C<ev_child> - watch out for process status changes
 
 Child watchers trigger when your process receives a SIGCHLD in response to
-some child status changes (most typically when a child of yours dies). It
-is permissible to install a child watcher I<after> the child has been
-forked (which implies it might have already exited), as long as the event
-loop isn't entered (or is continued from a watcher).
+some child status changes (most typically when a child of yours dies or
+exits). It is permissible to install a child watcher I<after> the child
+has been forked (which implies it might have already exited), as long
+as the event loop isn't entered (or is continued from a watcher), i.e.,
+forking and then immediately registering a watcher for the child is fine,
+but forking and registering a watcher a few event loop iterations later is
+not.
 
 Only the default event loop is capable of handling signals, and therefore
 you can only register child watchers in the default event loop.
@@ -1562,6 +1681,13 @@
 event-based approach to child reaping and thus use libev's support for
 that, so other libev users can use C<ev_child> watchers freely.
 
+=head3 Stopping the Child Watcher
+
+Currently, the child watcher never gets stopped, even when the
+child terminates, so normally one needs to stop the watcher in the
+callback. Future versions of libev might stop the watcher automatically
+when a child exit is detected.
+
 =head3 Watcher-Specific Functions and Data Members
 
 =over 4
@@ -1599,29 +1725,29 @@
 Example: C<fork()> a new process and install a child handler to wait for
 its completion.
 
-  ev_child cw;
+   ev_child cw;
+
+   static void
+   child_cb (EV_P_ struct ev_child *w, int revents)
+   {
+     ev_child_stop (EV_A_ w);
+     printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
+   }
+
+   pid_t pid = fork ();
 
-  static void
-  child_cb (EV_P_ struct ev_child *w, int revents)
-  {
-    ev_child_stop (EV_A_ w);
-    printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
-  }
-
-  pid_t pid = fork ();
-
-  if (pid < 0)
-    // error
-  else if (pid == 0)
-    {
-      // the forked child executes here
-      exit (1);
-    }
-  else
-    {
-      ev_child_init (&cw, child_cb, pid, 0);
-      ev_child_start (EV_DEFAULT_ &cw);
-    }
+   if (pid < 0)
+     // error
+   else if (pid == 0)
+     {
+       // the forked child executes here
+       exit (1);
+     }
+   else
+     {
+       ev_child_init (&cw, child_cb, pid, 0);
+       ev_child_start (EV_DEFAULT_ &cw);
+     }
 
 
 =head2 C<ev_stat> - did the file attributes just change?
@@ -1639,66 +1765,71 @@
 The path I<should> be absolute and I<must not> end in a slash. If it is
 relative and your working directory changes, the behaviour is undefined.
 
-Since there is no standard to do this, the portable implementation simply
-calls C<stat (2)> regularly on the path to see if it changed somehow. You
-can specify a recommended polling interval for this case. If you specify
-a polling interval of C<0> (highly recommended!) then a I<suitable,
-unspecified default> value will be used (which you can expect to be around
-five seconds, although this might change dynamically). Libev will also
-impose a minimum interval which is currently around C<0.1>, but thats
-usually overkill.
+Since there is no standard kernel interface to do this, the portable
+implementation simply calls C<stat (2)> regularly on the path to see if
+it changed somehow. You can specify a recommended polling interval for
+this case. If you specify a polling interval of C<0> (highly recommended!)
+then a I<suitable, unspecified default> value will be used (which
+you can expect to be around five seconds, although this might change
+dynamically). Libev will also impose a minimum interval which is currently
+around C<0.1>, but thats usually overkill.
 
 This watcher type is not meant for massive numbers of stat watchers,
 as even with OS-supported change notifications, this can be
 resource-intensive.
 
-At the time of this writing, only the Linux inotify interface is
-implemented (implementing kqueue support is left as an exercise for the
-reader, note, however, that the author sees no way of implementing ev_stat
-semantics with kqueue). Inotify will be used to give hints only and should
-not change the semantics of C<ev_stat> watchers, which means that libev
-sometimes needs to fall back to regular polling again even with inotify,
-but changes are usually detected immediately, and if the file exists there
-will be no polling.
+At the time of this writing, the only OS-specific interface implemented
+is the Linux inotify interface (implementing kqueue support is left as
+an exercise for the reader. Note, however, that the author sees no way
+of implementing C<ev_stat> semantics with kqueue).
 
 =head3 ABI Issues (Largefile Support)
 
 Libev by default (unless the user overrides this) uses the default
-compilation environment, which means that on systems with optionally
-disabled large file support, you get the 32 bit version of the stat
+compilation environment, which means that on systems with large file
+support disabled by default, you get the 32 bit version of the stat
 structure. When using the library from programs that change the ABI to
 use 64 bit file offsets the programs will fail. In that case you have to
 compile libev with the same flags to get binary compatibility. This is
 obviously the case with any flags that change the ABI, but the problem is
-most noticeably with ev_stat and large file support.
+most noticeably disabled with ev_stat and large file support.
 
-=head3 Inotify
-
-When C<inotify (7)> support has been compiled into libev (generally only
-available on Linux) and present at runtime, it will be used to speed up
-change detection where possible. The inotify descriptor will be created lazily
-when the first C<ev_stat> watcher is being started.
+The solution for this is to lobby your distribution maker to make large
+file interfaces available by default (as e.g. FreeBSD does) and not
+optional. Libev cannot simply switch on large file support because it has
+to exchange stat structures with application programs compiled using the
+default compilation environment.
+
+=head3 Inotify and Kqueue
+
+When C<inotify (7)> support has been compiled into libev (generally
+only available with Linux 2.6.25 or above due to bugs in earlier
+implementations) and present at runtime, it will be used to speed up
+change detection where possible. The inotify descriptor will be created
+lazily when the first C<ev_stat> watcher is being started.
 
 Inotify presence does not change the semantics of C<ev_stat> watchers
 except that changes might be detected earlier, and in some cases, to avoid
 making regular C<stat> calls. Even in the presence of inotify support
-there are many cases where libev has to resort to regular C<stat> polling.
+there are many cases where libev has to resort to regular C<stat> polling,
+but as long as the path exists, libev usually gets away without polling.
 
-(There is no support for kqueue, as apparently it cannot be used to
+There is no support for kqueue, as apparently it cannot be used to
 implement this functionality, due to the requirement of having a file
-descriptor open on the object at all times).
+descriptor open on the object at all times, and detecting renames, unlinks
+etc. is difficult.
 
 =head3 The special problem of stat time resolution
 
 The C<stat ()> system call only supports full-second resolution portably, and
-even on systems where the resolution is higher, many file systems still
+even on systems where the resolution is higher, most file systems still
 only support whole seconds.
 
 That means that, if the time is the only thing that changes, you can
 easily miss updates: on the first update, C<ev_stat> detects a change and
 calls your callback, which does something. When there is another update
-within the same second, C<ev_stat> will be unable to detect it as the stat
-data does not change.
+within the same second, C<ev_stat> will be unable to detect unless the
+stat data does change in other ways (e.g. file size).
 
 The solution to this is to delay acting on a change for slightly more
 than a second (or till slightly after the next full second boundary), using
@@ -1728,9 +1859,9 @@
 a suitable value. The memory pointed to by C<path> must point to the same
 path for as long as the watcher is active.
 
-The callback will receive C<EV_STAT> when a change was detected, relative
-to the attributes at the time the watcher was started (or the last change
-was detected).
+The callback will receive an C<EV_STAT> event when a change was detected,
+relative to the attributes at the time the watcher was started (or the
+last change was detected).
 
 =item ev_stat_stat (loop, ev_stat *)
 
@@ -1769,62 +1900,62 @@
 
 Example: Watch C</etc/passwd> for attribute changes.
 
-  static void
-  passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
-  {
-    /* /etc/passwd changed in some way */
-    if (w->attr.st_nlink)
-      {
-        printf ("passwd current size  %ld\n", (long)w->attr.st_size);
-        printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
-        printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
-      }
-    else
-      /* you shalt not abuse printf for puts */
-      puts ("wow, /etc/passwd is not there, expect problems. "
-            "if this is windows, they already arrived\n");
-  }
+   static void
+   passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
+   {
+     /* /etc/passwd changed in some way */
+     if (w->attr.st_nlink)
+       {
+         printf ("passwd current size  %ld\n", (long)w->attr.st_size);
+         printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
+         printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
+       }
+     else
+       /* you shalt not abuse printf for puts */
+       puts ("wow, /etc/passwd is not there, expect problems. "
+             "if this is windows, they already arrived\n");
+   }
 
-  ...
-  ev_stat passwd;
+   ...
+   ev_stat passwd;
 
-  ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
-  ev_stat_start (loop, &passwd);
+   ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
+   ev_stat_start (loop, &passwd);
 
 Example: Like above, but additionally use a one-second delay so we do not
 miss updates (however, frequent updates will delay processing, too, so
 one might do the work both on C<ev_stat> callback invocation I<and> on
 C<ev_timer> callback invocation).
 
-  static ev_stat passwd;
-  static ev_timer timer;
+   static ev_stat passwd;
+   static ev_timer timer;
 
-  static void
-  timer_cb (EV_P_ ev_timer *w, int revents)
-  {
-    ev_timer_stop (EV_A_ w);
-
-    /* now it's one second after the most recent passwd change */
-  }
-
-  static void
-  stat_cb (EV_P_ ev_stat *w, int revents)
-  {
-    /* reset the one-second timer */
-    ev_timer_again (EV_A_ &timer);
-  }
-
-  ...
-  ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
-  ev_stat_start (loop, &passwd);
-  ev_timer_init (&timer, timer_cb, 0., 1.02);
+   static void
+   timer_cb (EV_P_ ev_timer *w, int revents)
+   {
+     ev_timer_stop (EV_A_ w);
+
+     /* now it's one second after the most recent passwd change */
+   }
+
+   static void
+   stat_cb (EV_P_ ev_stat *w, int revents)
+   {
+     /* reset the one-second timer */
+     ev_timer_again (EV_A_ &timer);
+   }
+
+   ...
+   ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
+   ev_stat_start (loop, &passwd);
+   ev_timer_init (&timer, timer_cb, 0., 1.02);
 
 
 =head2 C<ev_idle> - when you've got nothing better to do...
 
 Idle watchers trigger events when no other events of the same or higher
-priority are pending (prepare, check and other idle watchers do not
-count).
+priority are pending (prepare, check and other idle watchers do not count
+as receiving "events").
 
 That is, as long as your process is busy handling sockets or timeouts
 (or even signals, imagine) of the same or higher priority it will not be
@@ -1858,22 +1989,22 @@
 Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
 callback, free it. Also, use no error checking, as usual.
 
-  static void
-  idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
-  {
-    free (w);
-    // now do something you wanted to do when the program has
-    // no longer anything immediate to do.
-  }
-
-  struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
-  ev_idle_init (idle_watcher, idle_cb);
-  ev_idle_start (loop, idle_cb);
+   static void
+   idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
+   {
+     free (w);
+     // now do something you wanted to do when the program has
+     // no longer anything immediate to do.
+   }
+
+   struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
+   ev_idle_init (idle_watcher, idle_cb);
+   ev_idle_start (loop, idle_cb);
 
 
 =head2 C<ev_prepare> and C<ev_check> - customise your event loop!
 
-Prepare and check watchers are usually (but not always) used in tandem:
+Prepare and check watchers are usually (but not always) used in pairs:
 prepare watchers get invoked before the process blocks and check watchers
 afterwards.
 
@@ -1886,21 +2017,21 @@
 called in pairs bracketing the blocking call.
 
 Their main purpose is to integrate other event mechanisms into libev and
-their use is somewhat advanced. This could be used, for example, to track
+their use is somewhat advanced. They could be used, for example, to track
 variable changes, implement your own watchers, integrate net-snmp or a
 coroutine library and lots more. They are also occasionally useful if
 you cache some data and want to flush it before blocking (for example,
 in X programs you might want to do an C<XFlush ()> in an C<ev_prepare>
 watcher).
 
-This is done by examining in each prepare call which file descriptors need
-to be watched by the other library, registering C<ev_io> watchers for
-them and starting an C<ev_timer> watcher for any timeouts (many libraries
-provide just this functionality). Then, in the check watcher you check for
-any events that occurred (by checking the pending status of all watchers
-and stopping them) and call back into the library. The I/O and timer
-callbacks will never actually be called (but must be valid nevertheless,
-because you never know, you know?).
+This is done by examining in each prepare call which file descriptors
+need to be watched by the other library, registering C<ev_io> watchers
+for them and starting an C<ev_timer> watcher for any timeouts (many
+libraries provide exactly this functionality). Then, in the check watcher,
+you check for any events that occurred (by checking the pending status
+of all watchers and stopping them) and call back into the library. The
+I/O and timer callbacks will never actually be called (but must be valid
+nevertheless, because you never know, you know?).
 
 As another example, the Perl Coro module uses these hooks to integrate
 coroutines into libev programs, by yielding to other active coroutines
@@ -1913,13 +2044,15 @@
 
 It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
 priority, to ensure that they are being run before any other watchers
-after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
-too) should not activate ("feed") events into libev. While libev fully
-supports this, they might get executed before other C<ev_check> watchers
-did their job. As C<ev_check> watchers are often used to embed other
-(non-libev) event loops those other event loops might be in an unusable
-state until their C<ev_check> watcher ran (always remind yourself to
-coexist peacefully with others).
+after the poll (this doesn't matter for C<ev_prepare> watchers).
+
+Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not
+activate ("feed") events into libev. While libev fully supports this, they
+might get executed before other C<ev_check> watchers did their job. As
+C<ev_check> watchers are often used to embed other (non-libev) event
+loops those other event loops might be in an unusable state until their
+C<ev_check> watcher ran (always remind yourself to coexist peacefully with
+others).
 
 =head3 Watcher-Specific Functions and Data Members
 
@@ -1931,7 +2064,8 @@
 
 Initialises and configures the prepare or check watcher - they have no
 parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
-macros, but using them is utterly, utterly and completely pointless.
+macros, but using them is utterly, utterly, utterly and completely
+pointless.
 
 =back
 
@@ -1950,60 +2084,60 @@
 priority for the check watcher or use C<ev_clear_pending> explicitly, as
 the callbacks for the IO/timeout watchers might not have been called yet.
 
-  static ev_io iow [nfd];
-  static ev_timer tw;
+   static ev_io iow [nfd];
+   static ev_timer tw;
+
+   static void
+   io_cb (ev_loop *loop, ev_io *w, int revents)
+   {
+   }
+
+   // create io watchers for each fd and a timer before blocking
+   static void
+   adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
+   {
+     int timeout = 3600000;
+     struct pollfd fds [nfd];
+     // actual code will need to loop here and realloc etc.
+     adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
+
+     /* the callback is illegal, but won't be called as we stop during check */
+     ev_timer_init (&tw, 0, timeout * 1e-3);
+     ev_timer_start (loop, &tw);
+
+     // create one ev_io per pollfd
+     for (int i = 0; i < nfd; ++i)
+       {
+         ev_io_init (iow + i, io_cb, fds [i].fd,
+           ((fds [i].events & POLLIN ? EV_READ : 0)
+            | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
+
+         fds [i].revents = 0;
+         ev_io_start (loop, iow + i);
+       }
+   }
 
-  static void
-  io_cb (ev_loop *loop, ev_io *w, int revents)
-  {
-  }
-
-  // create io watchers for each fd and a timer before blocking
-  static void
-  adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
-  {
-    int timeout = 3600000;
-    struct pollfd fds [nfd];
-    // actual code will need to loop here and realloc etc.
-    adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
-
-    /* the callback is illegal, but won't be called as we stop during check */
-    ev_timer_init (&tw, 0, timeout * 1e-3);
-    ev_timer_start (loop, &tw);
-
-    // create one ev_io per pollfd
-    for (int i = 0; i < nfd; ++i)
-      {
-        ev_io_init (iow + i, io_cb, fds [i].fd,
-          ((fds [i].events & POLLIN ? EV_READ : 0)
-           | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
-
-        fds [i].revents = 0;
-        ev_io_start (loop, iow + i);
-      }
-  }
-
-  // stop all watchers after blocking
-  static void
-  adns_check_cb (ev_loop *loop, ev_check *w, int revents)
-  {
-    ev_timer_stop (loop, &tw);
-
-    for (int i = 0; i < nfd; ++i)
-      {
-        // set the relevant poll flags
-        // could also call adns_processreadable etc. here
-        struct pollfd *fd = fds + i;
-        int revents = ev_clear_pending (iow + i);
-        if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
-        if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
-
-        // now stop the watcher
-        ev_io_stop (loop, iow + i);
-      }
+   // stop all watchers after blocking
+   static void
+   adns_check_cb (ev_loop *loop, ev_check *w, int revents)
+   {
+     ev_timer_stop (loop, &tw);
 
-    adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
-  }
+     for (int i = 0; i < nfd; ++i)
+       {
+         // set the relevant poll flags
+         // could also call adns_processreadable etc. here
+         struct pollfd *fd = fds + i;
+         int revents = ev_clear_pending (iow + i);
+         if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
+         if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
+
+         // now stop the watcher
+         ev_io_stop (loop, iow + i);
+       }
+
+     adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
+   }
 
 Method 2: This would be just like method 1, but you run C<adns_afterpoll>
 in the prepare watcher and would dispose of the check watcher.
@@ -2012,57 +2146,58 @@
 notification (libadns does), you can also make use of the actual watcher
 callbacks, and only destroy/create the watchers in the prepare watcher.
 
-  static void
-  timer_cb (EV_P_ ev_timer *w, int revents)
-  {
-    adns_state ads = (adns_state)w->data;
-    update_now (EV_A);
-
-    adns_processtimeouts (ads, &tv_now);
-  }
-
-  static void
-  io_cb (EV_P_ ev_io *w, int revents)
-  {
-    adns_state ads = (adns_state)w->data;
-    update_now (EV_A);
-
-    if (revents & EV_READ ) adns_processreadable  (ads, w->fd, &tv_now);
-    if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
-  }
+   static void
+   timer_cb (EV_P_ ev_timer *w, int revents)
+   {
+     adns_state ads = (adns_state)w->data;
+     update_now (EV_A);
+
+     adns_processtimeouts (ads, &tv_now);
+   }
+
+   static void
+   io_cb (EV_P_ ev_io *w, int revents)
+   {
+     adns_state ads = (adns_state)w->data;
+     update_now (EV_A);
 
-  // do not ever call adns_afterpoll
+     if (revents & EV_READ ) adns_processreadable  (ads, w->fd, &tv_now);
+     if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
+   }
+
+   // do not ever call adns_afterpoll
 
 Method 4: Do not use a prepare or check watcher because the module you
-want to embed is too inflexible to support it. Instead, you can override
-their poll function.  The drawback with this solution is that the main
-loop is now no longer controllable by EV. The C<Glib::EV> module does
-this.
-
-  static gint
-  event_poll_func (GPollFD *fds, guint nfds, gint timeout)
-  {
-    int got_events = 0;
-
-    for (n = 0; n < nfds; ++n)
-      // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
-
-    if (timeout >= 0)
-      // create/start timer
-
-    // poll
-    ev_loop (EV_A_ 0);
-
-    // stop timer again
-    if (timeout >= 0)
-      ev_timer_stop (EV_A_ &to);
-
-    // stop io watchers again - their callbacks should have set
-    for (n = 0; n < nfds; ++n)
-      ev_io_stop (EV_A_ iow [n]);
+want to embed is not flexible enough to support it. Instead, you can
+override their poll function. The drawback with this solution is that the
+main loop is now no longer controllable by EV. The C<Glib::EV> module uses
+this approach, effectively embedding EV as a client into the horrible
+libglib event loop.
 
-    return got_events;
-  }
+   static gint
+   event_poll_func (GPollFD *fds, guint nfds, gint timeout)
+   {
+     int got_events = 0;
+
+     for (n = 0; n < nfds; ++n)
+       // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
+
+     if (timeout >= 0)
+       // create/start timer
+
+     // poll
+     ev_loop (EV_A_ 0);
+
+     // stop timer again
+     if (timeout >= 0)
+       ev_timer_stop (EV_A_ &to);
+
+     // stop io watchers again - their callbacks should have set
+     for (n = 0; n < nfds; ++n)
+       ev_io_stop (EV_A_ iow [n]);
+
+     return got_events;
+   }
 
 
 =head2 C<ev_embed> - when one backend isn't enough...
@@ -2078,16 +2213,17 @@
 As an example for a bug workaround, the kqueue backend might only support
 sockets on some platform, so it is unusable as generic backend, but you
 still want to make use of it because you have many sockets and it scales
-so nicely. In this case, you would create a kqueue-based loop and embed it
-into your default loop (which might use e.g. poll). Overall operation will
-be a bit slower because first libev has to poll and then call kevent, but
-at least you can use both at what they are best.
-
-As for prioritising I/O: rarely you have the case where some fds have
-to be watched and handled very quickly (with low latency), and even
-priorities and idle watchers might have too much overhead. In this case
-you would put all the high priority stuff in one loop and all the rest in
-a second one, and embed the second one in the first.
+so nicely. In this case, you would create a kqueue-based loop and embed
+it into your default loop (which might use e.g. poll). Overall operation
+will be a bit slower because first libev has to call C<poll> and then
+C<kevent>, but at least you can use both mechanisms for what they are
+best: C<kqueue> for scalable sockets and C<poll> if you want it to work :)
+
+As for prioritising I/O: under rare circumstances you have the case where
+some fds have to be watched and handled very quickly (with low latency),
+and even priorities and idle watchers might have too much overhead. In
+this case you would put all the high priority stuff in one loop and all
+the rest in a second one, and embed the second one in the first.
 
 As long as the watcher is active, the callback will be invoked every time
 there might be events pending in the embedded loop. The callback must then
@@ -2105,9 +2241,10 @@
 Also, there have not currently been made special provisions for forking:
 when you fork, you not only have to call C<ev_loop_fork> on both loops,
 but you will also have to stop and restart any C<ev_embed> watchers
-yourself.
+yourself - but you can use a fork watcher to handle this automatically,
+and future versions of libev might do just that.
 
-Unfortunately, not all backends are embeddable, only the ones returned by
+Unfortunately, not all backends are embeddable: only the ones returned by
 C<ev_embeddable_backends> are, which, unfortunately, does not include any
 portable one.
 
@@ -2116,6 +2253,14 @@
 this is to have a separate variables for your embeddable loop, try to
 create it, and if that fails, use the normal loop for everything.
 
+=head3 C<ev_embed> and fork
+
+While the C<ev_embed> watcher is running, forks in the embedding loop will
+automatically be applied to the embedded loop as well, so no special
+fork handling is required in that case. When the watcher is not running,
+however, it is still the task of the libev user to call C<ev_loop_fork ()>
+as applicable.
+
 =head3 Watcher-Specific Functions and Data Members
 
 =over 4
@@ -2150,45 +2295,45 @@
 C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
 used).
 
-  struct ev_loop *loop_hi = ev_default_init (0);
-  struct ev_loop *loop_lo = 0;
-  struct ev_embed embed;
-  
-  // see if there is a chance of getting one that works
-  // (remember that a flags value of 0 means autodetection)
-  loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
-    ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
-    : 0;
-
-  // if we got one, then embed it, otherwise default to loop_hi
-  if (loop_lo)
-    {
-      ev_embed_init (&embed, 0, loop_lo);
-      ev_embed_start (loop_hi, &embed);
-    }
-  else
-    loop_lo = loop_hi;
+   struct ev_loop *loop_hi = ev_default_init (0);
+   struct ev_loop *loop_lo = 0;
+   struct ev_embed embed;
+   
+   // see if there is a chance of getting one that works
+   // (remember that a flags value of 0 means autodetection)
+   loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
+     ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
+     : 0;
+
+   // if we got one, then embed it, otherwise default to loop_hi
+   if (loop_lo)
+     {
+       ev_embed_init (&embed, 0, loop_lo);
+       ev_embed_start (loop_hi, &embed);
+     }
+   else
+     loop_lo = loop_hi;
 
 Example: Check if kqueue is available but not recommended and create
 a kqueue backend for use with sockets (which usually work with any
 kqueue implementation). Store the kqueue/socket-only event loop in
 C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
 
-  struct ev_loop *loop = ev_default_init (0);
-  struct ev_loop *loop_socket = 0;
-  struct ev_embed embed;
-  
-  if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
-    if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
-      {
-        ev_embed_init (&embed, 0, loop_socket);
-        ev_embed_start (loop, &embed);
-      }
+   struct ev_loop *loop = ev_default_init (0);
+   struct ev_loop *loop_socket = 0;
+   struct ev_embed embed;
+   
+   if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
+     if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
+       {
+         ev_embed_init (&embed, 0, loop_socket);
+         ev_embed_start (loop, &embed);
+       }
 
-  if (!loop_socket)
-    loop_socket = loop;
+   if (!loop_socket)
+     loop_socket = loop;
 
-  // now use loop_socket for all sockets, and loop for everything else
+   // now use loop_socket for all sockets, and loop for everything else
 
 
 =head2 C<ev_fork> - the audacity to resume the event loop after a fork
@@ -2242,7 +2387,7 @@
 need elaborate support such as pthreads.
 
 That means that if you want to queue data, you have to provide your own
-queue. But at least I can tell you would implement locking around your
+queue. But at least I can tell you how to implement locking around your
 queue:
 
 =over 4
@@ -2250,8 +2395,8 @@
 =item queueing from a signal handler context
 
 To implement race-free queueing, you simply add to the queue in the signal
-handler but you block the signal handler in the watcher callback. Here is an example that does that for
-some fictitious SIGUSR1 handler:
+handler but you block the signal handler in the watcher callback. Here is
+an example that does that for some fictitious SIGUSR1 handler:
 
    static ev_async mysig;
 
@@ -2328,13 +2473,13 @@
 
 Initialises and configures the async watcher - it has no parameters of any
 kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless,
-believe me.
+trust me.
 
 =item ev_async_send (loop, ev_async *)
 
 Sends/signals/activates the given C<ev_async> watcher, that is, feeds
 an C<EV_ASYNC> event on the watcher into the event loop. Unlike
-C<ev_feed_event>, this call is safe to do in other threads, signal or
+C<ev_feed_event>, this call is safe to do from other threads, signal or
 similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
 section below on what exactly this means).
 
@@ -2368,34 +2513,37 @@
 =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)
 
 This function combines a simple timer and an I/O watcher, calls your
-callback on whichever event happens first and automatically stop both
+callback on whichever event happens first and automatically stops both
 watchers. This is useful if you want to wait for a single event on an fd
 or timeout without having to allocate/configure/start/stop/free one or
 more watchers yourself.
 
-If C<fd> is less than 0, then no I/O watcher will be started and events
-is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
-C<events> set will be created and started.
+If C<fd> is less than 0, then no I/O watcher will be started and the
+C<events> argument is being ignored. Otherwise, an C<ev_io> watcher for
+the given C<fd> and C<events> set will be created and started.
 
 If C<timeout> is less than 0, then no timeout watcher will be
 started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
-repeat = 0) will be started. While C<0> is a valid timeout, it is of
-dubious value.
+repeat = 0) will be started. C<0> is a valid timeout.
 
 The callback has the type C<void (*cb)(int revents, void *arg)> and gets
 passed an C<revents> set like normal event callbacks (a combination of
 C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
-value passed to C<ev_once>:
+value passed to C<ev_once>. Note that it is possible to receive I<both>
+a timeout and an io event at the same time - you probably should give io
+events precedence.
 
-  static void stdin_ready (int revents, void *arg)
-  {
-    if (revents & EV_TIMEOUT)
-      /* doh, nothing entered */;
-    else if (revents & EV_READ)
-      /* stdin might have data for us, joy! */;
-  }
+Example: wait up to ten seconds for data to appear on STDIN_FILENO.
 
-  ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
+   static void stdin_ready (int revents, void *arg)
+   {
+     if (revents & EV_READ)
+       /* stdin might have data for us, joy! */;
+     else if (revents & EV_TIMEOUT)
+       /* doh, nothing entered */;
+   }
+
+   ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
 
 =item ev_feed_event (ev_loop *, watcher *, int revents)
 
@@ -2454,7 +2602,7 @@
 
 To use it,
    
-  #include <ev++.h>
+   #include <ev++.h>
 
 This automatically includes F<ev.h> and puts all of its definitions (many
 of them macros) into the global namespace. All C++ specific things are
@@ -2531,14 +2679,14 @@
 
 Example: simple class declaration and watcher initialisation
 
-  struct myclass
-  {
-    void io_cb (ev::io &w, int revents) { }
-  }
-
-  myclass obj;
-  ev::io iow;
-  iow.set <myclass, &myclass::io_cb> (&obj);
+   struct myclass
+   {
+     void io_cb (ev::io &w, int revents) { }
+   }
+
+   myclass obj;
+   ev::io iow;
+   iow.set <myclass, &myclass::io_cb> (&obj);
 
 =item w->set<function> (void *data = 0)
 
@@ -2550,10 +2698,10 @@
 
 See the method-C<set> above for more details.
 
-Example:
+Example: Use a plain function as callback.
 
-  static void io_cb (ev::io &w, int revents) { }
-  iow.set <io_cb> ();
+   static void io_cb (ev::io &w, int revents) { }
+   iow.set <io_cb> ();
 
 =item w->set (struct ev_loop *)
 
@@ -2596,19 +2744,19 @@
 Example: Define a class with an IO and idle watcher, start one of them in
 the constructor.
 
-  class myclass
-  {
-    ev::io   io;  void io_cb   (ev::io   &w, int revents);
-    ev:idle idle  void idle_cb (ev::idle &w, int revents);
-
-    myclass (int fd)
-    {
-      io  .set <myclass, &myclass::io_cb  > (this);
-      idle.set <myclass, &myclass::idle_cb> (this);
-
-      io.start (fd, ev::READ);
-    }
-  };
+   class myclass
+   {
+     ev::io   io  ; void io_cb   (ev::io   &w, int revents);
+     ev::idle idle; void idle_cb (ev::idle &w, int revents);
+
+     myclass (int fd)
+     {
+       io  .set <myclass, &myclass::io_cb  > (this);
+       idle.set <myclass, &myclass::idle_cb> (this);
+
+       io.start (fd, ev::READ);
+     }
+   };
 
 
 =head1 OTHER LANGUAGE BINDINGS
@@ -2625,12 +2773,22 @@
 The EV module implements the full libev API and is actually used to test
 libev. EV is developed together with libev. Apart from the EV core module,
 there are additional modules that implement libev-compatible interfaces
-to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
-C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
+to C<libadns> (C<EV::ADNS>, but C<AnyEvent::DNS> is preferred nowadays),
+C<Net::SNMP> (C<Net::SNMP::EV>) and the C<libglib> event core (C<Glib::EV>
+and C<EV::Glib>).
 
-It can be found and installed via CPAN, its homepage is found at
+It can be found and installed via CPAN, its homepage is at
 L<http://software.schmorp.de/pkg/EV>.
 
+=item Python
+
+Python bindings can be found at L<http://code.google.com/p/pyev/>. It
+seems to be quite complete and well-documented. Note, however, that the
+patch they require for libev is outright dangerous as it breaks the ABI
+for everybody else, and therefore, should never be applied in an installed
+libev (if python requires an incompatible ABI then it needs to embed
+libev).
+
 =item Ruby
 
 Tony Arcieri has written a ruby extension that offers access to a subset
@@ -2641,7 +2799,7 @@
 =item D
 
 Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
-be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.
+be found at L<http://proj.llucax.com.ar/wiki/evd>.
 
 =back
 
@@ -2663,9 +2821,9 @@
 loop argument"). The C<EV_A> form is used when this is the sole argument,
 C<EV_A_> is used when other arguments are following. Example:
 
-  ev_unref (EV_A);
-  ev_timer_add (EV_A_ watcher);
-  ev_loop (EV_A_ 0);
+   ev_unref (EV_A);
+   ev_timer_add (EV_A_ watcher);
+   ev_loop (EV_A_ 0);
 
 It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
 which is often provided by the following macro.
@@ -2676,11 +2834,11 @@
 loop parameter"). The C<EV_P> form is used when this is the sole parameter,
 C<EV_P_> is used when other parameters are following. Example:
 
-  // this is how ev_unref is being declared
-  static void ev_unref (EV_P);
+   // this is how ev_unref is being declared
+   static void ev_unref (EV_P);
 
-  // this is how you can declare your typical callback
-  static void cb (EV_P_ ev_timer *w, int revents)
+   // this is how you can declare your typical callback
+   static void cb (EV_P_ ev_timer *w, int revents)
 
 It declares a parameter C<loop> of type C<struct ev_loop *>, quite
 suitable for use with C<EV_A>.
@@ -2706,16 +2864,16 @@
 macros so it will work regardless of whether multiple loops are supported
 or not.
 
-  static void
-  check_cb (EV_P_ ev_timer *w, int revents)
-  {
-    ev_check_stop (EV_A_ w);
-  }
-
-  ev_check check;
-  ev_check_init (&check, check_cb);
-  ev_check_start (EV_DEFAULT_ &check);
-  ev_loop (EV_DEFAULT_ 0);
+   static void
+   check_cb (EV_P_ ev_timer *w, int revents)
+   {
+     ev_check_stop (EV_A_ w);
+   }
+
+   ev_check check;
+   ev_check_init (&check, check_cb);
+   ev_check_start (EV_DEFAULT_ &check);
+   ev_loop (EV_DEFAULT_ 0);
 
 =head1 EMBEDDING
 
@@ -2739,8 +2897,8 @@
 To include only the libev core (all the C<ev_*> functions), with manual
 configuration (no autoconf):
 
-  #define EV_STANDALONE 1
-  #include "ev.c"
+   #define EV_STANDALONE 1
+   #include "ev.c"
 
 This will automatically include F<ev.h>, too, and should be done in a
 single C source file only to provide the function implementations. To use
@@ -2748,8 +2906,8 @@
 done by writing a wrapper around F<ev.h> that you can include instead and
 where you can put other configuration options):
 
-  #define EV_STANDALONE 1
-  #include "ev.h"
+   #define EV_STANDALONE 1
+   #include "ev.h"
 
 Both header files and implementation files can be compiled with a C++
 compiler (at least, thats a stated goal, and breakage will be treated
@@ -2758,18 +2916,18 @@
 You need the following files in your source tree, or in a directory
 in your include path (e.g. in libev/ when using -Ilibev):
 
-  ev.h
-  ev.c
-  ev_vars.h
-  ev_wrap.h
-
-  ev_win32.c      required on win32 platforms only
-
-  ev_select.c     only when select backend is enabled (which is enabled by default)
-  ev_poll.c       only when poll backend is enabled (disabled by default)
-  ev_epoll.c      only when the epoll backend is enabled (disabled by default)
-  ev_kqueue.c     only when the kqueue backend is enabled (disabled by default)
-  ev_port.c       only when the solaris port backend is enabled (disabled by default)
+   ev.h
+   ev.c
+   ev_vars.h
+   ev_wrap.h
+
+   ev_win32.c      required on win32 platforms only
+
+   ev_select.c     only when select backend is enabled (which is enabled by default)
+   ev_poll.c       only when poll backend is enabled (disabled by default)
+   ev_epoll.c      only when the epoll backend is enabled (disabled by default)
+   ev_kqueue.c     only when the kqueue backend is enabled (disabled by default)
+   ev_port.c       only when the solaris port backend is enabled (disabled by default)
 
 F<ev.c> includes the backend files directly when enabled, so you only need
 to compile this single file.
@@ -2778,18 +2936,18 @@
 
 To include the libevent compatibility API, also include:
 
-  #include "event.c"
+   #include "event.c"
 
 in the file including F<ev.c>, and:
 
-  #include "event.h"
+   #include "event.h"
 
 in the files that want to use the libevent API. This also includes F<ev.h>.
 
 You need the following additional files for this:
 
-  event.h
-  event.c
+   event.h
+   event.c
 
 =head3 AUTOCONF SUPPORT
 
@@ -2800,13 +2958,13 @@
 
 For this of course you need the m4 file:
 
-  libev.m4
+   libev.m4
 
 =head2 PREPROCESSOR SYMBOLS/MACROS
 
 Libev can be configured via a variety of preprocessor symbols you have to
 define before including any of its files. The default in the absence of
-autoconf is noted for every option.
+autoconf is documented for every option.
 
 =over 4
 
@@ -2986,8 +3144,8 @@
 and time, so using the defaults of five priorities (-2 .. +2) is usually
 fine.
 
-If your embedding application does not need any priorities, defining these both to
-C<0> will save some memory and CPU.
+If your embedding application does not need any priorities, defining these
+both to C<0> will save some memory and CPU.
 
 =item EV_PERIODIC_ENABLE
 
@@ -3004,7 +3162,8 @@
 =item EV_EMBED_ENABLE
 
 If undefined or defined to be C<1>, then embed watchers are supported. If
-defined to be C<0>, then they are not.
+defined to be C<0>, then they are not. Embed watchers rely on most other
+watcher types, which therefore must not be disabled.
 
 =item EV_STAT_ENABLE
 
@@ -3046,9 +3205,9 @@
 =item EV_USE_4HEAP
 
 Heaps are not very cache-efficient. To improve the cache-efficiency of the
-timer and periodics heap, libev uses a 4-heap when this symbol is defined
-to C<1>. The 4-heap uses more complicated (longer) code but has
-noticeably faster performance with many (thousands) of watchers.
+timer and periodics heaps, libev uses a 4-heap when this symbol is defined
+to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
+faster performance with many (thousands) of watchers.
 
 The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
 (disabled).
@@ -3056,11 +3215,11 @@
 =item EV_HEAP_CACHE_AT
 
 Heaps are not very cache-efficient. To improve the cache-efficiency of the
-timer and periodics heap, libev can cache the timestamp (I<at>) within
+timer and periodics heaps, libev can cache the timestamp (I<at>) within
 the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
 which uses 8-12 bytes more per watcher and a few hundred bytes more code,
 but avoids random read accesses on heap changes. This improves performance
-noticeably with with many (hundreds) of watchers.
+noticeably with many (hundreds) of watchers.
 
 The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
 (disabled).
@@ -3076,7 +3235,7 @@
 libev considerably.
 
 The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
-C<0.>
+C<0>.
 
 =item EV_COMMON
 
@@ -3087,9 +3246,9 @@
 
 For example, the perl EV module uses something like this:
 
-  #define EV_COMMON                       \
-    SV *self; /* contains this struct */  \
-    SV *cb_sv, *fh /* note no trailing ";" */
+   #define EV_COMMON                       \
+     SV *self; /* contains this struct */  \
+     SV *cb_sv, *fh /* note no trailing ";" */
 
 =item EV_CB_DECLARE (type)
 
@@ -3104,14 +3263,16 @@
 avoid the C<struct ev_loop *> as first argument in all cases, or to use
 method calls instead of plain function calls in C++.
 
+=back
+
 =head2 EXPORTED API SYMBOLS
 
 If you need to re-export the API (e.g. via a DLL) and you need a list of
 exported symbols, you can use the provided F<Symbol.*> files which list
 all public symbols, one per line:
 
-  Symbols.ev      for libev proper
-  Symbols.event   for the libevent emulation
+   Symbols.ev      for libev proper
+   Symbols.event   for the libevent emulation
 
 This can also be used to rename all public symbols to avoid clashes with
 multiple versions of libev linked together (which is obviously bad in
@@ -3142,41 +3303,51 @@
 The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
 that everybody includes and which overrides some configure choices:
 
-  #define EV_MINIMAL 1
-  #define EV_USE_POLL 0
-  #define EV_MULTIPLICITY 0
-  #define EV_PERIODIC_ENABLE 0
-  #define EV_STAT_ENABLE 0
-  #define EV_FORK_ENABLE 0
-  #define EV_CONFIG_H <config.h>
-  #define EV_MINPRI 0
-  #define EV_MAXPRI 0
+   #define EV_MINIMAL 1
+   #define EV_USE_POLL 0
+   #define EV_MULTIPLICITY 0
+   #define EV_PERIODIC_ENABLE 0
+   #define EV_STAT_ENABLE 0
+   #define EV_FORK_ENABLE 0
+   #define EV_CONFIG_H <config.h>
+   #define EV_MINPRI 0
+   #define EV_MAXPRI 0
 
-  #include "ev++.h"
+   #include "ev++.h"
 
 And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
 
-  #include "ev_cpp.h"
-  #include "ev.c"
-
+   #include "ev_cpp.h"
+   #include "ev.c"
 
-=head1 THREADS AND COROUTINES
+=head1 INTERACTION WITH OTHER PROGRAMS OR LIBRARIES
 
-=head2 THREADS
+=head2 THREADS AND COROUTINES
 
-Libev itself is completely thread-safe, but it uses no locking. This
-means that you can use as many loops as you want in parallel, as long as
-only one thread ever calls into one libev function with the same loop
-parameter.
+=head3 THREADS
 
-Or put differently: calls with different loop parameters can be done in
-parallel from multiple threads, calls with the same loop parameter must be
-done serially (but can be done from different threads, as long as only one
-thread ever is inside a call at any point in time, e.g. by using a mutex
-per loop).
-
-If you want to know which design is best for your problem, then I cannot
-help you but by giving some generic advice:
+All libev functions are reentrant and thread-safe unless explicitly
+documented otherwise, but libev implements no locking itself. This means
+that you can use as many loops as you want in parallel, as long as there
+are no concurrent calls into any libev function with the same loop
+parameter (C<ev_default_*> calls have an implicit default loop parameter,
+of course): libev guarantees that different event loops share no data
+structures that need any locking.
+
+Or to put it differently: calls with different loop parameters can be done
+concurrently from multiple threads, calls with the same loop parameter
+must be done serially (but can be done from different threads, as long as
+only one thread ever is inside a call at any point in time, e.g. by using
+a mutex per loop).
+
+Specifically to support threads (and signal handlers), libev implements
+so-called C<ev_async> watchers, which allow some limited form of
+concurrency on the same event loop, namely waking it up "from the
+outside".
+
+If you want to know which design (one loop, locking, or multiple loops
+without or something else still) is best for your problem, then I cannot
+help you, but here is some generic advice:
 
 =over 4
 
@@ -3198,96 +3369,96 @@
 better than you currently do :-)
 
 =item * often you need to talk to some other thread which blocks in the
-event loop - C<ev_async> watchers can be used to wake them up from other
-threads safely (or from signal contexts...).
+event loop.
+
+C<ev_async> watchers can be used to wake them up from other threads safely
+(or from signal contexts...).
+
+An example use would be to communicate signals or other events that only
+work in the default loop by registering the signal watcher with the
+default loop and triggering an C<ev_async> watcher from the default loop
+watcher callback into the event loop interested in the signal.
 
 =back
 
-=head2 COROUTINES
+=head3 COROUTINES
 
-Libev is much more accommodating to coroutines ("cooperative threads"):
-libev fully supports nesting calls to it's functions from different
+Libev is very accommodating to coroutines ("cooperative threads"):
+libev fully supports nesting calls to its functions from different
 coroutines (e.g. you can call C<ev_loop> on the same loop from two
-different coroutines and switch freely between both coroutines running the
+different coroutines, and switch freely between both coroutines running the
 loop, as long as you don't confuse yourself). The only exception is that
 you must not do this from C<ev_periodic> reschedule callbacks.
 
-Care has been invested into making sure that libev does not keep local
-state inside C<ev_loop>, and other calls do not usually allow coroutine
-switches.
-
-
-=head1 COMPLEXITIES
-
-In this section the complexities of (many of) the algorithms used inside
-libev will be explained. For complexity discussions about backends see the
-documentation for C<ev_default_init>.
-
-All of the following are about amortised time: If an array needs to be
-extended, libev needs to realloc and move the whole array, but this
-happens asymptotically never with higher number of elements, so O(1) might
-mean it might do a lengthy realloc operation in rare cases, but on average
-it is much faster and asymptotically approaches constant time.
+Care has been taken to ensure that libev does not keep local state inside
+C<ev_loop>, and other calls do not usually allow for coroutine switches as
+they do not clal any callbacks.
 
-=over 4
+=head2 COMPILER WARNINGS
 
-=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
-
-This means that, when you have a watcher that triggers in one hour and
-there are 100 watchers that would trigger before that then inserting will
-have to skip roughly seven (C<ld 100>) of these watchers.
-
-=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
-
-That means that changing a timer costs less than removing/adding them
-as only the relative motion in the event queue has to be paid for.
-
-=item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)
-
-These just add the watcher into an array or at the head of a list.
+Depending on your compiler and compiler settings, you might get no or a
+lot of warnings when compiling libev code. Some people are apparently
+scared by this.
 
-=item Stopping check/prepare/idle/fork/async watchers: O(1)
+However, these are unavoidable for many reasons. For one, each compiler
+has different warnings, and each user has different tastes regarding
+warning options. "Warn-free" code therefore cannot be a goal except when
+targeting a specific compiler and compiler-version.
 
-=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
+Another reason is that some compiler warnings require elaborate
+workarounds, or other changes to the code that make it less clear and less
+maintainable.
 
-These watchers are stored in lists then need to be walked to find the
-correct watcher to remove. The lists are usually short (you don't usually
-have many watchers waiting for the same fd or signal).
+And of course, some compiler warnings are just plain stupid, or simply
+wrong (because they don't actually warn about the condition their message
+seems to warn about). For example, certain older gcc versions had some
+warnings that resulted an extreme number of false positives. These have
+been fixed, but some people still insist on making code warn-free with
+such buggy versions.
 
-=item Finding the next timer in each loop iteration: O(1)
+While libev is written to generate as few warnings as possible,
+"warn-free" code is not a goal, and it is recommended not to build libev
+with any compiler warnings enabled unless you are prepared to cope with
+them (e.g. by ignoring them). Remember that warnings are just that:
+warnings, not errors, or proof of bugs.
 
-By virtue of using a binary or 4-heap, the next timer is always found at a
-fixed position in the storage array.
 
-=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
+=head2 VALGRIND
 
-A change means an I/O watcher gets started or stopped, which requires
-libev to recalculate its status (and possibly tell the kernel, depending
-on backend and whether C<ev_io_set> was used).
+Valgrind has a special section here because it is a popular tool that is
+highly useful. Unfortunately, valgrind reports are very hard to interpret.
 
-=item Activating one watcher (putting it into the pending state): O(1)
+If you think you found a bug (memory leak, uninitialised data access etc.)
+in libev, then check twice: If valgrind reports something like:
 
-=item Priority handling: O(number_of_priorities)
+   ==2274==    definitely lost: 0 bytes in 0 blocks.
+   ==2274==      possibly lost: 0 bytes in 0 blocks.
+   ==2274==    still reachable: 256 bytes in 1 blocks.
 
-Priorities are implemented by allocating some space for each
-priority. When doing priority-based operations, libev usually has to
-linearly search all the priorities, but starting/stopping and activating
-watchers becomes O(1) w.r.t. priority handling.
+Then there is no memory leak, just as memory accounted to global variables
+is not a memleak - the memory is still being refernced, and didn't leak.
 
-=item Sending an ev_async: O(1)
+Similarly, under some circumstances, valgrind might report kernel bugs
+as if it were a bug in libev (e.g. in realloc or in the poll backend,
+although an acceptable workaround has been found here), or it might be
+confused.
 
-=item Processing ev_async_send: O(number_of_async_watchers)
+Keep in mind that valgrind is a very good tool, but only a tool. Don't
+make it into some kind of religion.
 
-=item Processing signals: O(max_signal_number)
+If you are unsure about something, feel free to contact the mailing list
+with the full valgrind report and an explanation on why you think this
+is a bug in libev (best check the archives, too :). However, don't be
+annoyed when you get a brisk "this is no bug" answer and take the chance
+of learning how to interpret valgrind properly.
 
-Sending involves a system call I<iff> there were no other C<ev_async_send>
-calls in the current loop iteration. Checking for async and signal events
-involves iterating over all running async watchers or all signal numbers.
+If you need, for some reason, empty reports from valgrind for your project
+I suggest using suppression lists.
 
-=back
 
+=head1 PORTABILITY NOTES
 
-=head1 Win32 platform limitations and workarounds
+=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
 
 Win32 doesn't support any of the standards (e.g. POSIX) that libev
 requires, and its I/O model is fundamentally incompatible with the POSIX
@@ -3304,6 +3475,13 @@
 There is no supported compilation method available on windows except
 embedding it into other applications.
 
+Not a libev limitation but worth mentioning: windows apparently doesn't
+accept large writes: instead of resulting in a partial write, windows will
+either accept everything or return C<ENOBUFS> if the buffer is too large,
+so make sure you only write small amounts into your sockets (less than a
+megabyte seems safe, but this apparently depends on the amount of memory
+available).
+
 Due to the many, low, and arbitrary limits on the win32 platform and
 the abysmal performance of winsockets, using a large number of sockets
 is not recommended (and not reasonable). If your program needs to use
@@ -3312,6 +3490,21 @@
 notification model, which cannot be implemented efficiently on windows
 (Microsoft monopoly games).
 
+A typical way to use libev under windows is to embed it (see the embedding
+section for details) and use the following F<evwrap.h> header file instead
+of F<ev.h>:
+
+   #define EV_STANDALONE              /* keeps ev from requiring config.h */
+   #define EV_SELECT_IS_WINSOCKET 1   /* configure libev for windows select */
+
+   #include "ev.h"
+
+And compile the following F<evwrap.c> file into your project (make sure
+you do I<not> compile the F<ev.c> or any other embedded source files!):
+
+   #include "evwrap.h"
+   #include "ev.c"
+
 =over 4
 
 =item The winsocket select function
@@ -3319,15 +3512,16 @@
 The winsocket C<select> function doesn't follow POSIX in that it
 requires socket I<handles> and not socket I<file descriptors> (it is
 also extremely buggy). This makes select very inefficient, and also
-requires a mapping from file descriptors to socket handles. See the
+requires a mapping from file descriptors to socket handles (the Microsoft
+C runtime provides the function C<_open_osfhandle> for this). See the
 discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
 C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
 
 The configuration for a "naked" win32 using the Microsoft runtime
 libraries and raw winsocket select is:
 
-  #define EV_USE_SELECT 1
-  #define EV_SELECT_IS_WINSOCKET 1   /* forces EV_SELECT_USE_FD_SET, too */
+   #define EV_USE_SELECT 1
+   #define EV_SELECT_IS_WINSOCKET 1   /* forces EV_SELECT_USE_FD_SET, too */
 
 Note that winsockets handling of fd sets is O(n), so you can easily get a
 complexity in the O(n²) range when using win32.
@@ -3361,18 +3555,26 @@
 
 =back
 
+=head2 PORTABILITY REQUIREMENTS
 
-=head1 PORTABILITY REQUIREMENTS
-
-In addition to a working ISO-C implementation, libev relies on a few
-additional extensions:
+In addition to a working ISO-C implementation and of course the
+backend-specific APIs, libev relies on a few additional extensions:
 
 =over 4
 
+=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
+calling conventions regardless of C<ev_watcher_type *>.
+
+Libev assumes not only that all watcher pointers have the same internal
+structure (guaranteed by POSIX but not by ISO C for example), but it also
+assumes that the same (machine) code can be used to call any watcher
+callback: The watcher callbacks have different type signatures, but libev
+calls them using an C<ev_watcher *> internally.
+
 =item C<sig_atomic_t volatile> must be thread-atomic as well
 
 The type C<sig_atomic_t volatile> (or whatever is defined as
-C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
+C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
 threads. This is not part of the specification for C<sig_atomic_t>, but is
 believed to be sufficiently portable.
 
@@ -3391,11 +3593,11 @@
 
 =item C<long> must be large enough for common memory allocation sizes
 
-To improve portability and simplify using libev, libev uses C<long>
-internally instead of C<size_t> when allocating its data structures. On
-non-POSIX systems (Microsoft...) this might be unexpectedly low, but
-is still at least 31 bits everywhere, which is enough for hundreds of
-millions of watchers.
+To improve portability and simplify its API, libev uses C<long> internally
+instead of C<size_t> when allocating its data structures. On non-POSIX
+systems (Microsoft...) this might be unexpectedly low, but is still at
+least 31 bits everywhere, which is enough for hundreds of millions of
+watchers.
 
 =item C<double> must hold a time value in seconds with enough accuracy
 
@@ -3409,56 +3611,75 @@
 If you know of other additional requirements drop me a note.
 
 
-=head1 COMPILER WARNINGS
+=head1 ALGORITHMIC COMPLEXITIES
 
-Depending on your compiler and compiler settings, you might get no or a
-lot of warnings when compiling libev code. Some people are apparently
-scared by this.
+In this section the complexities of (many of) the algorithms used inside
+libev will be documented. For complexity discussions about backends see
+the documentation for C<ev_default_init>.
 
-However, these are unavoidable for many reasons. For one, each compiler
-has different warnings, and each user has different tastes regarding
-warning options. "Warn-free" code therefore cannot be a goal except when
-targeting a specific compiler and compiler-version.
+All of the following are about amortised time: If an array needs to be
+extended, libev needs to realloc and move the whole array, but this
+happens asymptotically rarer with higher number of elements, so O(1) might
+mean that libev does a lengthy realloc operation in rare cases, but on
+average it is much faster and asymptotically approaches constant time.
 
-Another reason is that some compiler warnings require elaborate
-workarounds, or other changes to the code that make it less clear and less
-maintainable.
+=over 4
 
-And of course, some compiler warnings are just plain stupid, or simply
-wrong (because they don't actually warn about the condition their message
-seems to warn about).
+=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
 
-While libev is written to generate as few warnings as possible,
-"warn-free" code is not a goal, and it is recommended not to build libev
-with any compiler warnings enabled unless you are prepared to cope with
-them (e.g. by ignoring them). Remember that warnings are just that:
-warnings, not errors, or proof of bugs.
+This means that, when you have a watcher that triggers in one hour and
+there are 100 watchers that would trigger before that, then inserting will
+have to skip roughly seven (C<ld 100>) of these watchers.
 
+=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
 
-=head1 VALGRIND
+That means that changing a timer costs less than removing/adding them,
+as only the relative motion in the event queue has to be paid for.
 
-Valgrind has a special section here because it is a popular tool that is
-highly useful, but valgrind reports are very hard to interpret.
+=item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)
 
-If you think you found a bug (memory leak, uninitialised data access etc.)
-in libev, then check twice: If valgrind reports something like:
+These just add the watcher into an array or at the head of a list.
 
-   ==2274==    definitely lost: 0 bytes in 0 blocks.
-   ==2274==      possibly lost: 0 bytes in 0 blocks.
-   ==2274==    still reachable: 256 bytes in 1 blocks.
+=item Stopping check/prepare/idle/fork/async watchers: O(1)
 
-Then there is no memory leak. Similarly, under some circumstances,
-valgrind might report kernel bugs as if it were a bug in libev, or it
-might be confused (it is a very good tool, but only a tool).
+=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
 
-If you are unsure about something, feel free to contact the mailing list
-with the full valgrind report and an explanation on why you think this is
-a bug in libev. However, don't be annoyed when you get a brisk "this is
-no bug" answer and take the chance of learning how to interpret valgrind
-properly.
+These watchers are stored in lists, so they need to be walked to find the
+correct watcher to remove. The lists are usually short (you don't usually
+have many watchers waiting for the same fd or signal: one is typical, two
+is rare).
 
-If you need, for some reason, empty reports from valgrind for your project
-I suggest using suppression lists.
+=item Finding the next timer in each loop iteration: O(1)
+
+By virtue of using a binary or 4-heap, the next timer is always found at a
+fixed position in the storage array.
+
+=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
+
+A change means an I/O watcher gets started or stopped, which requires
+libev to recalculate its status (and possibly tell the kernel, depending
+on backend and whether C<ev_io_set> was used).
+
+=item Activating one watcher (putting it into the pending state): O(1)
+
+=item Priority handling: O(number_of_priorities)
+
+Priorities are implemented by allocating some space for each
+priority. When doing priority-based operations, libev usually has to
+linearly search all the priorities, but starting/stopping and activating
+watchers becomes O(1) with respect to priority handling.
+
+=item Sending an ev_async: O(1)
+
+=item Processing ev_async_send: O(number_of_async_watchers)
+
+=item Processing signals: O(max_signal_number)
+
+Sending involves a system call I<iff> there were no other C<ev_async_send>
+calls in the current loop iteration. Checking for async and signal events
+involves iterating over all running async watchers or all signal numbers.
+
+=back
 
 
 =head1 AUTHOR