[ViewVC] Diff of: cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.384 by sf-exg, Sun Oct 16 11:02:57 2011 UTC vs.
Revision 1.414 by root, Fri May 4 20:50:57 2012 UTC

 =head1 WHAT TO READ WHEN IN A HURRY
 This manual tries to be very detailed, but unfortunately, this also makes
 it very long. If you just want to know the basics of libev, I suggest
-reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and
+reading L</ANATOMY OF A WATCHER>, then the L</EXAMPLE PROGRAM> above and
-look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and
+look up the missing functions in L</GLOBAL FUNCTIONS> and the C<ev_io> and
-C<ev_timer> sections in L<WATCHER TYPES>.
+C<ev_timer> sections in L</WATCHER TYPES>.
 =head1 ABOUT LIBEV
 Libev is an event loop: you register interest in certain events (such as a
 file descriptor being readable or a timeout occurring), and it will manage
 the current system, you would need to look at C<ev_embeddable_backends ()
 & ev_supported_backends ()>, likewise for recommended ones.
 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) throw ())
 Sets the allocation function to use (the prototype is similar - the
 semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
 used to allocate and free memory (no surprises here). If it returns zero
 when memory needs to be allocated (C<size != 0>), the library might abort
    }
    ...
    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) throw ())
 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
 indicating the system call or subsystem causing the problem. If this
 callback is set, then libev will expect it to remedy the situation, no
 It scales in the same way as the epoll backend, but the interface to the
 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 (but
+two event changes per incident. Support for C<fork ()> is very bad (you
-sane, unlike epoll) and it drops fds silently in similarly hard-to-detect
+might have to leak fd's on fork, but it's more sane than epoll) and it
-cases
+drops fds silently in similarly hard-to-detect cases
 This backend usually performs well under most conditions.
 While nominally embeddable in other event loops, this doesn't work
 everywhere, so you might need to test for this. And since it is broken
 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 L<The special problem of time updates> in the C<ev_timer> section.
+See also L</The special problem of time updates> in the C<ev_timer> section.
 =item ev_suspend (loop)
 =item ev_resume (loop)
 without a previous call to C<ev_suspend>.
 Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
 event loop time (see C<ev_now_update>).
-=item ev_run (loop, int flags)
+=item bool ev_run (loop, int flags)
 Finally, this is it, the event handler. This function usually is called
 after you have initialised all your watchers and you want to start
 handling events. It will ask the operating system for any new events, call
-the watcher callbacks, an then repeat the whole process indefinitely: This
+the watcher callbacks, and then repeat the whole process indefinitely: This
 is why event loops are called I<loops>.
 If the flags argument is specified as C<0>, it will keep handling events
 until either no event watchers are active anymore or C<ev_break> was
 called.
+The return value is false if there are no more active watchers (which
+usually means "all jobs done" or "deadlock"), and true in all other cases
+(which usually means " you should call C<ev_run> again").
 Please note that an explicit C<ev_break> 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, that is truly a thing of
 beauty.
-This function is also I<mostly> exception-safe - you can break out of
+This function is I<mostly> exception-safe - you can break out of a
-a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
+C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
 exception and so on. This does not decrement the C<ev_depth> value, nor
 will it clear any outstanding C<EVBREAK_ONE> breaks.
 A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
 those events and any already outstanding ones, but will not wait and
 invoke the actual watchers inside another context (another thread etc.).
 If you want to reset the callback, use C<ev_invoke_pending> as new
 callback.
-=item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))
+=item ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ())
 Sometimes you want to share the same loop between multiple threads. This
 can be done relatively simply by putting mutex_lock/unlock calls around
 each call to a libev function.
 However, C<ev_run> can run an indefinite time, so it is not feasible
 to wait for it to return. One way around this is to wake up the event
-loop via C<ev_break> and C<av_async_send>, another way is to set these
+loop via C<ev_break> and C<ev_async_send>, another way is to set these
 I<release> and I<acquire> callbacks on the loop.
 When set, then C<release> will be called just before the thread is
 suspended waiting for new events, and C<acquire> is called just
 afterwards.
 =item C<EV_PREPARE>
 =item C<EV_CHECK>
-All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
+All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts to
-to gather new events, and all C<ev_check> watchers are invoked just after
+gather new events, and all C<ev_check> watchers are queued (not invoked)
-C<ev_run> has gathered them, but before it invokes any callbacks for any
+just after C<ev_run> has gathered them, but before it queues any callbacks
+for any received events. That means C<ev_prepare> watchers are the last
+watchers invoked before the event loop sleeps or polls for new events, and
+C<ev_check> watchers will be invoked before any other watchers of the same
+or lower priority within an event loop iteration.
-received events. Callbacks of both watcher types can start and stop as
+Callbacks of both watcher types can start and stop as many watchers as
-many watchers as they want, and all of them will be taken into account
+they want, and all of them will be taken into account (for example, a
-(for example, a C<ev_prepare> watcher might start an idle watcher to keep
+C<ev_prepare> watcher might start an idle watcher to keep C<ev_run> from
-C<ev_run> from blocking).
+blocking).
 =item C<EV_EMBED>
 The embedded event loop specified in the C<ev_embed> watcher needs attention.
 =item callback ev_cb (ev_TYPE *watcher)
 Returns the callback currently set on the watcher.
-=item ev_cb_set (ev_TYPE *watcher, callback)
+=item ev_set_cb (ev_TYPE *watcher, callback)
 Change the callback. You can change the callback at virtually any time
 (modulo threads).
 =item ev_set_priority (ev_TYPE *watcher, int priority)
 or might not have been clamped to the valid range.
 The default priority used by watchers when no priority has been set is
 always C<0>, which is supposed to not be too high and not be too low :).
-See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of
+See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of
 priorities.
 =item ev_invoke (loop, ev_TYPE *watcher, int revents)
 Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
 See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
 functions that do not need a watcher.
 =back
-See also the L<ASSOCIATING CUSTOM DATA WITH A WATCHER> and L<BUILDING YOUR
+See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR
 OWN COMPOSITE WATCHERS> idioms.
 =head2 WATCHER STATES
 There are various watcher states mentioned throughout this manual -
 In this case, it would be more efficient to leave the C<ev_timer> alone,
 but remember the time of last activity, and check for a real timeout only
 within the callback:
+   ev_tstamp timeout = 60.;
    ev_tstamp last_activity; // time of last activity
+   ev_timer timer;
    static void
    callback (EV_P_ ev_timer *w, int revents)
    {
-     ev_tstamp now     = ev_now (EV_A);
+     // calculate when the timeout would happen
-     ev_tstamp timeout = last_activity + 60.;
+     ev_tstamp after = last_activity - ev_now (EV_A) + timeout;
-     // if last_activity + 60. is older than now, we did time out
+     // if negative, it means we the timeout already occurred
-     if (timeout < now)
+     if (after < 0.)
        {
          // timeout occurred, take action
        }
      else
        {
-         // callback was invoked, but there was some activity, re-arm
+         // callback was invoked, but there was some recent
-         // the watcher to fire in last_activity + 60, which is
+         // activity. simply restart the timer to time out
-         // guaranteed to be in the future, so "again" is positive:
+         // after "after" seconds, which is the earliest time
-         w->repeat = timeout - now;
+         // the timeout can occur.
+         ev_timer_set (w, after, 0.);
-         ev_timer_again (EV_A_ w);
+         ev_timer_start (EV_A_ w);
        }
    }
-To summarise the callback: first calculate the real timeout (defined
+To summarise the callback: first calculate in how many seconds the
-as "60 seconds after the last activity"), then check if that time has
+timeout will occur (by calculating the absolute time when it would occur,
-been reached, which means something I<did>, in fact, time out. Otherwise
+C<last_activity + timeout>, and subtracting the current time, C<ev_now
-the callback was invoked too early (C<timeout> is in the future), so
+(EV_A)> from that).
-re-schedule the timer to fire at that future time, to see if maybe we have
-a timeout then.
-Note how C<ev_timer_again> is used, taking advantage of the
+If this value is negative, then we are already past the timeout, i.e. we
-C<ev_timer_again> optimisation when the timer is already running.
+timed out, and need to do whatever is needed in this case.
+Otherwise, we now the earliest time at which the timeout would trigger,
+and simply start the timer with this timeout value.
+In other words, each time the callback is invoked it will check whether
+the timeout occurred. If not, it will simply reschedule itself to check
+again at the earliest time it could time out. Rinse. Repeat.
 This scheme causes more callback invocations (about one every 60 seconds
 minus half the average time between activity), but virtually no calls to
 libev to change the timeout.
-To start the timer, simply initialise the watcher and set C<last_activity>
+To start the machinery, simply initialise the watcher and set
-to the current time (meaning we just have some activity :), then call the
+C<last_activity> to the current time (meaning there was some activity just
-callback, which will "do the right thing" and start the timer:
+now), then call the callback, which will "do the right thing" and start
+the timer:
+   last_activity = ev_now (EV_A);
-   ev_init (timer, callback);
+   ev_init (&timer, callback);
-   last_activity = ev_now (loop);
+   callback (EV_A_ &timer, 0);
-   callback (loop, timer, EV_TIMER);
-And when there is some activity, simply store the current time in
+When there is some activity, simply store the current time in
 C<last_activity>, no libev calls at all:
+   if (activity detected)
-   last_activity = ev_now (loop);
+     last_activity = ev_now (EV_A);
+When your timeout value changes, then the timeout can be changed by simply
+providing a new value, stopping the timer and calling the callback, which
+will again do the right thing (for example, time out immediately :).
+   timeout = new_value;
+   ev_timer_stop (EV_A_ &timer);
+   callback (EV_A_ &timer, 0);
 This technique is slightly more complex, but in most cases where the
 time-out is unlikely to be triggered, much more efficient.
-Changing the timeout is trivial as well (if it isn't hard-coded in the
-callback :) - just change the timeout and invoke the callback, which will
-fix things for you.
 =item 4. Wee, just use a double-linked list for your timeouts.
 If there is not one request, but many thousands (millions...), all
 employing some kind of timeout with the same timeout value, then one can
 If you ask a timer to call your callback after three seconds, then
 you expect it to be invoked after three seconds - but of course, this
 cannot be guaranteed to infinite precision. Less obviously, it cannot be
 guaranteed to any precision by libev - imagine somebody suspending the
-process a STOP signal for a few hours for example.
+process with a STOP signal for a few hours for example.
 So, libev tries to invoke your callback as soon as possible I<after> the
 delay has occurred, but cannot guarantee this.
 A less obvious failure mode is calling your callback too early: many event
 keep up with the timer (because it takes longer than those 10 seconds to
 do stuff) the timer will not fire more than once per event loop iteration.
 =item ev_timer_again (loop, ev_timer *)
-This will act as if the timer timed out and restarts it again if it is
+This will act as if the timer timed out, and restarts it again if it is
-repeating. The exact semantics are:
+repeating. It basically works like calling C<ev_timer_stop>, updating the
+timeout to the C<repeat> value and calling C<ev_timer_start>.
+The exact semantics are as in the following rules, all of which will be
+applied to the watcher:
+=over 4
-If the timer is pending, its pending status is cleared.
+=item If the timer is pending, the pending status is always cleared.
-If the timer is started but non-repeating, stop it (as if it timed out).
+=item If the timer is started but non-repeating, stop it (as if it timed
+out, without invoking it).
-If the timer is repeating, either start it if necessary (with the
+=item If the timer is repeating, make the C<repeat> value the new timeout
-C<repeat> value), or reset the running timer to the C<repeat> value.
+and start the timer, if necessary.
+=back
-This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
+This sounds a bit complicated, see L</Be smart about timeouts>, above, for a
 usage example.
 =item ev_tstamp ev_timer_remaining (loop, ev_timer *)
 Returns the remaining time until a timer fires. If the timer is active,
 Apart from keeping your process non-blocking (which is a useful
 effect on its own sometimes), idle watchers are a good place to do
 "pseudo-background processing", or delay processing stuff to after the
 event loop has handled all outstanding events.
+=head3 Abusing an C<ev_idle> watcher for its side-effect
+As long as there is at least one active idle watcher, libev will never
+sleep unnecessarily. Or in other words, it will loop as fast as possible.
+For this to work, the idle watcher doesn't need to be invoked at all - the
+lowest priority will do.
+This mode of operation can be useful together with an C<ev_check> watcher,
+to do something on each event loop iteration - for example to balance load
+between different connections.
+See L</Abusing an C<ev_check> watcher for its side-effect> for a longer
+example.
 =head3 Watcher-Specific Functions and Data Members
 =over 4
 =item ev_idle_init (ev_idle *, callback)
 callback, free it. Also, use no error checking, as usual.
    static void
    idle_cb (struct ev_loop *loop, ev_idle *w, int revents)
    {
+     // stop the watcher
+     ev_idle_stop (loop, w);
+     // now we can free it
      free (w);
      // now do something you wanted to do when the program has
      // no longer anything immediate to do.
    }
    ev_idle *idle_watcher = malloc (sizeof (ev_idle));
    ev_idle_start (loop, idle_watcher);
 =head2 C<ev_prepare> and C<ev_check> - customise your event loop!
-Prepare and check watchers are usually (but not always) used in pairs:
+Prepare and check watchers are often (but not always) used in pairs:
 prepare watchers get invoked before the process blocks and check watchers
 afterwards.
 You I<must not> call C<ev_run> or similar functions that enter
 the current event loop from either C<ev_prepare> or C<ev_check>
 with priority higher than or equal to the event loop and one coroutine
 of lower priority, but only once, using idle watchers to keep the event
 loop from blocking if lower-priority coroutines are active, thus mapping
 low-priority coroutines to idle/background tasks).
-It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
+When used for this purpose, it is recommended to give C<ev_check> watchers
-priority, to ensure that they are being run before any other watchers
+highest (C<EV_MAXPRI>) priority, to ensure that they are being run before
-after the poll (this doesn't matter for C<ev_prepare> watchers).
+any other watchers 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 Abusing an C<ev_check> watcher for its side-effect
+C<ev_check> (and less often also C<ev_prepare>) watchers can also be
+useful because they are called once per event loop iteration. For
+example, if you want to handle a large number of connections fairly, you
+normally only do a bit of work for each active connection, and if there
+is more work to do, you wait for the next event loop iteration, so other
+connections have a chance of making progress.
+Using an C<ev_check> watcher is almost enough: it will be called on the
+next event loop iteration. However, that isn't as soon as possible -
+without external events, your C<ev_check> watcher will not be invoked.
+This is where C<ev_idle> watchers come in handy - all you need is a
+single global idle watcher that is active as long as you have one active
+C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop
+will not sleep, and the C<ev_check> watcher makes sure a callback gets
+invoked. Neither watcher alone can do that.
 =head3 Watcher-Specific Functions and Data Members
 =over 4
 it by calling C<ev_async_send>, which is thread- and signal safe.
 This functionality is very similar to C<ev_signal> watchers, as signals,
 too, are asynchronous in nature, and signals, too, will be compressed
 (i.e. the number of callback invocations may be less than the number of
-C<ev_async_sent> calls). In fact, you could use signal watchers as a kind
+C<ev_async_send> calls). In fact, you could use signal watchers as a kind
 of "global async watchers" by using a watcher on an otherwise unused
 signal, and C<ev_feed_signal> to signal this watcher from another thread,
 even without knowing which loop owns the signal.
 =head3 Queueing
    ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
 =item ev_feed_fd_event (loop, int fd, int revents)
 Feed an event on the given fd, as if a file descriptor backend detected
-the given events it.
+the given events.
 =item ev_feed_signal_event (loop, int signum)
 Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
 which is async-safe.
    {
      struct my_biggy big = (struct my_biggy *)
        (((char *)w) - offsetof (struct my_biggy, t2));
    }
+=head2 AVOIDING FINISHING BEFORE RETURNING
+Often you have structures like this in event-based programs:
+  callback ()
+  {
+    free (request);
+  }
+  request = start_new_request (..., callback);
+The intent is to start some "lengthy" operation. The C<request> could be
+used to cancel the operation, or do other things with it.
+It's not uncommon to have code paths in C<start_new_request> that
+immediately invoke the callback, for example, to report errors. Or you add
+some caching layer that finds that it can skip the lengthy aspects of the
+operation and simply invoke the callback with the result.
+The problem here is that this will happen I<before> C<start_new_request>
+has returned, so C<request> is not set.
+Even if you pass the request by some safer means to the callback, you
+might want to do something to the request after starting it, such as
+canceling it, which probably isn't working so well when the callback has
+already been invoked.
+A common way around all these issues is to make sure that
+C<start_new_request> I<always> returns before the callback is invoked. If
+C<start_new_request> immediately knows the result, it can artificially
+delay invoking the callback by e.g. using a C<prepare> or C<idle> watcher
+for example, or more sneakily, by reusing an existing (stopped) watcher
+and pushing it into the pending queue:
+   ev_set_cb (watcher, callback);
+   ev_feed_event (EV_A_ watcher, 0);
+This way, C<start_new_request> can safely return before the callback is
+invoked, while not delaying callback invocation too much.
 =head2 MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS
 Often (especially in GUI toolkits) there are places where you have
 I<modal> interaction, which is most easily implemented by recursively
 invoking C<ev_run>.
    int exit_main_loop = 0;
    while (!exit_main_loop)
      ev_run (EV_DEFAULT_ EVRUN_ONCE);
-   // in a model watcher
+   // in a modal watcher
    int exit_nested_loop = 0;
    while (!exit_nested_loop)
      ev_run (EV_A_ EVRUN_ONCE);
 called):
    void
    wait_for_event (ev_watcher *w)
    {
-     ev_cb_set (w) = current_coro;
+     ev_set_cb (w, current_coro);
      switch_to (libev_coro);
    }
 That basically suspends the coroutine inside C<wait_for_event> and
 continues the libev coroutine, which, when appropriate, switches back to
-this or any other coroutine. I am sure if you sue this your own :)
+this or any other coroutine.
 You can do similar tricks if you have, say, threads with an event queue -
 instead of storing a coroutine, you store the queue object and instead of
 switching to a coroutine, you push the watcher onto the queue and notify
 any waiters.
-To embed libev, see L<EMBEDDING>, but in short, it's easiest to create two
+To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two
 files, F<my_ev.h> and F<my_ev.c> that include the respective libev files:
    // my_ev.h
    #define EV_CB_DECLARE(type)   struct my_coro *cb;
    #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb);
 to use the libev header file and library.
 =back
 =head1 C++ SUPPORT
+=head2 C API
+The normal C API should work fine when used from C++: both ev.h and the
+libev sources can be compiled as C++. Therefore, code that uses the C API
+will work fine.
+Proper exception specifications might have to be added to callbacks passed
+to libev: exceptions may be thrown only from watcher callbacks, all
+other callbacks (allocator, syserr, loop acquire/release and periodioc
+reschedule callbacks) must not throw exceptions, and might need a C<throw
+()> specification. If you have code that needs to be compiled as both C
+and C++ you can use the C<EV_THROW> macro for this:
+   static void
+   fatal_error (const char *msg) EV_THROW
+   {
+     perror (msg);
+     abort ();
+   }
+   ...
+   ev_set_syserr_cb (fatal_error);
+The only API functions that can currently throw exceptions are C<ev_run>,
+C<ev_invoke>, C<ev_invoke_pending> and C<ev_loop_destroy> (the latter
+because it runs cleanup watchers).
+Throwing exceptions in watcher callbacks is only supported if libev itself
+is compiled with a C++ compiler or your C and C++ environments allow
+throwing exceptions through C libraries (most do).
+=head2 C++ API
 Libev comes with some simplistic wrapper classes for C++ that mainly allow
 you to use some convenience methods to start/stop watchers and also change
 the callback model to a model using method callbacks on objects.
 with C<operator ()> can be used as callbacks. Other types should be easy
 to add as long as they only need one additional pointer for context. If
 you need support for other types of functors please contact the author
 (preferably after implementing it).
+For all this to work, your C++ compiler either has to use the same calling
+conventions as your C compiler (for static member functions), or you have
+to embed libev and compile libev itself as C++.
 Here is a list of things available in the C<ev> namespace:
 =over 4
 =item C<ev::READ>, C<ev::WRITE> etc.
 =item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc.
 For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of
 the same name in the C<ev> namespace, with the exception of C<ev_signal>
 which is called C<ev::sig> to avoid clashes with the C<signal> macro
-defines by many implementations.
+defined by many implementations.
 All of those classes have these methods:
 =over 4
 If defined to be C<1>, libev will compile in support for the Linux inotify
 interface to speed up C<ev_stat> watchers. Its actual availability will
 be detected at runtime. If undefined, it will be enabled if the headers
 indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
+=item EV_NO_SMP
+If defined to be C<1>, libev will assume that memory is always coherent
+between threads, that is, threads can be used, but threads never run on
+different cpus (or different cpu cores). This reduces dependencies
+and makes libev faster.
+=item EV_NO_THREADS
+If defined to be C<1>, libev will assume that it will never be called
+from different threads, which is a stronger assumption than C<EV_NO_SMP>,
+above. This reduces dependencies and makes libev faster.
 =item EV_ATOMIC_T
 Libev requires an integer type (suitable for storing C<0> or C<1>) whose
 access is atomic and serialised with respect to other threads or signal
 contexts. No such type is easily found in the C language, so you can
    #define EV_USE_POLL 1
    #define EV_CHILD_ENABLE 1
    #define EV_ASYNC_ENABLE 1
 The actual value is a bitset, it can be a combination of the following
-values:
+values (by default, all of these are enabled):
 =over 4
 =item C<1> - faster/larger code
 code size by roughly 30% on amd64).
 When optimising for size, use of compiler flags such as C<-Os> with
 gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
 assertions.
+The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler
+(e.g. gcc with C<-Os>).
 =item C<2> - faster/larger data structures
 Replaces the small 2-heap for timer management by a faster 4-heap, larger
 hash table sizes and so on. This will usually further increase code size
 and can additionally have an effect on the size of data structures at
 runtime.
+The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler
+(e.g. gcc with C<-Os>).
 =item C<4> - full API configuration
 This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
 enables multiplicity (C<EV_MULTIPLICITY>=1).
 With an intelligent-enough linker (gcc+binutils are intelligent enough
 when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
 your program might be left out as well - a binary starting a timer and an
 I/O watcher then might come out at only 5Kb.
+=item EV_API_STATIC
+If this symbol is defined (by default it is not), then all identifiers
+will have static linkage. This means that libev will not export any
+identifiers, and you cannot link against libev anymore. This can be useful
+when you embed libev, only want to use libev functions in a single file,
+and do not want its identifiers to be visible.
+To use this, define C<EV_API_STATIC> and include F<ev.c> in the file that
+wants to use libev.
+This option only works when libev is compiled with a C compiler, as C++
+doesn't support the required declaration syntax.
 =item EV_AVOID_STDIO
 If this is set to C<1> at compiletime, then libev will avoid using stdio
 functions (printf, scanf, perror etc.). This will increase the code size
 default loop and triggering an C<ev_async> watcher from the default loop
 watcher callback into the event loop interested in the signal.
 =back
-See also L<THREAD LOCKING EXAMPLE>.
+See also L</THREAD LOCKING EXAMPLE>.
 =head3 COROUTINES
 Libev is very accommodating to coroutines ("cooperative threads"):
 libev fully supports nesting calls to its functions from different
 =over 4
 =item C<EV_COMPAT3> backwards compatibility mechanism
 The backward compatibility mechanism can be controlled by
-C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
+C<EV_COMPAT3>. See L</PREPROCESSOR SYMBOLS/MACROS> in the L</EMBEDDING>
 section.
 =item C<ev_default_destroy> and C<ev_default_fork> have been removed
 These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
 =over 4
 =item active
 A watcher is active as long as it has been started and not yet stopped.
-See L<WATCHER STATES> for details.
+See L</WATCHER STATES> for details.
 =item application
 In this document, an application is whatever is using libev.
 watchers and events.
 =item pending
 A watcher is pending as soon as the corresponding event has been
-detected. See L<WATCHER STATES> for details.
+detected. See L</WATCHER STATES> for details.
 =item real time
 The physical time that is observed. It is apparently strictly monotonic :)

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Comparing libev/ev.pod (file contents): Revision 1.384 by sf-exg, Sun Oct 16 11:02:57 2011 UTC vs. Revision 1.414 by root, Fri May 4 20:50:57 2012 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.384 by sf-exg, Sun Oct 16 11:02:57 2011 UTC vs.
Revision 1.414 by root, Fri May 4 20:50:57 2012 UTC