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@@ -1,128 +1,56 @@ libev is a high-performance event loop/event model with lots of features. (see benchmark at http://libev.schmorp.de/bench.html) - Homepage: http://software.schmorp.de/pkg/libev - E-Mail: libev@lists.schmorp.de - Library Documentation: http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod - - It is modelled (very losely) after libevent and the Event perl module, - but aims to be faster and more correct, and also more featureful. And - also smaller. Yay. -ABOUT THIS DISTRIBUTION +ABOUT - If you downloaded the libevent+libev distribution of libev, you will - find it looks very much like libevent. In fact, the distributed libev - tarballs are indeed libevent tarballs patched up with the libev - event core, taking the evbuffer, evtag, evdns and evhttpd parts from - libevent (they use the libevent emulation inside libev). Configure and - Makefile stuff is also a more or less direct copy of libevent, and are - maintained by the libevent authors. - - If you downloaded the libev distribution (without libevent), then - you only get the core parts of the library, meaning http and dns - client/server code and similar things are missing. Only the core event - loop is included. + Homepage: http://software.schmorp.de/pkg/libev + Mailinglist: libev@lists.schmorp.de + http://lists.schmorp.de/cgi-bin/mailman/listinfo/libev + Library Documentation: http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod - If you are looking for an easily embeddable version, I recommend using - the libev standalone distribution or the CVS repository. + Libev is modelled (very losely) after libevent and the Event perl + module, but is faster, scales better and is more correct, and also more + featureful. And also smaller. Yay. + + Some of the specialties of libev not commonly found elsewhere are: + + - extensive and detailed, readable documentation (not doxygen garbage). + - fully supports fork, can detect fork in various ways and automatically + re-arms kernel mechanisms that do not support fork. + - highly optimised select, poll, epoll, kqueue and event ports backends. + - filesystem object (path) watching (with optional linux inotify support). + - wallclock-based times (using absolute time, cron-like). + - relative timers/timeouts (handle time jumps). + - fast intra-thread communication between multiple + event loops (with optional fast linux eventfd backend). + - extremely easy to embed. + - very small codebase, no bloated library. + - fully extensible by being able to plug into the event loop, + integrate other event loops, integrate other event loop users. + - very little memory use (small watchers, small event loop data). + - optional C++ interface allowing method and function callbacks + at no extra memory or runtime overhead. + - optional Perl interface with similar characteristics (capable + of running Glib/Gtk2 on libev, interfaces with Net::SNMP and + libadns). + - support for other languages (multiple C++ interfaces, D, Ruby, + Python) available from third-parties. Examples of programs that embed libev: the EV perl module, - rxvt-unicode, gvpe (GNU Virtual Private Ethernet) and deliantra - (http://www.deliantra.net). - -DIFFERENCES AND COMPARISON TO LIBEVENT - - The comparisons below are relative to libevent-1.3e. - - - multiple watchers can wait for the same event without deregistering others, - both for file descriptors as well as signals. - (registering two read events on fd 10 and unregistering one will not - break the other). - - - fork() is supported and can be handled - (there is no way to recover from a fork with libevent). - - - timers are handled as a priority queue (important operations are O(1)) - (libevent uses a much less efficient but more complex red-black tree). - - - supports absolute (wallclock-based) timers in addition to relative ones, - i.e. can schedule timers to occur after n seconds, or at a specific time. - - - timers can be repeating (both absolute and relative ones). - - - absolute timers can have customised rescheduling hooks (suitable for cron-like - applications). - - - detects time jumps and adjusts timers - (works for both forward and backward time jumps and also for absolute timers). - - - race-free signal processing - (libevent may delay processing signals till after the next event). - - - more efficient epoll backend - (stopping and starting an io watcher between two loop iterations will not - result in spurious epoll_ctl calls). - - - usually less calls to gettimeofday and clock_gettime - (libevent calls it on every timer event change, libev twice per iteration). - - - watchers use less memory - (libevent watcher on amd64: 152 bytes, libev native: <= 56 bytes, libevent emulation: 144 bytes). - - - library uses less memory - (libevent allocates large data structures wether used or not, libev - scales all its data structures dynamically). - - - no hardcoded arbitrary limits - (libevent contains an off-by-one bug and sometimes hardcodes limits). - - - libev separates timer, signal and io watchers from each other - (libevent combines them, but with libev you can combine them yourself - by reusing the same callback and still save memory). - - - simpler design, backends are potentially much simpler - (in libevent, backends have to deal with watchers, thus the problems with - wildly different semantics between diferent backends) - (epoll backend in libevent: 366 lines no caching, libev: 90 lines full caching). - - - libev handles EBADF gracefully by removing the offending fds. - - - libev communicates errors to the callback, libevent to the - event adder or not at all. - - - doesn't rely on nonportable BSD header files. - - - an event.h compatibility header exists, and can be used to run a wide - range of libevent programs unchanged (such as evdns.c). - - - win32 compatibility for the core parts. - (the backend is fd-based as documented and on other platforms, - not handle-based like libevent, and can be used for both winscoket environments - and unix-like ones). - - - libev can be embedded easily with or without autoconf support into - other programs, with no changes to the source code necessary. - - - the event core library (ev and event layer) compiles and works both as - C and C++. - - - a simple C++ wrapper that supports methods as callbacks exists. - - - a full featured and widely used perl module is available. - - whats missing? + rxvt-unicode, gvpe (GNU Virtual Private Ethernet), the Deliantra MMORPG + server (http://www.deliantra.net/), Rubinius (a next-generation Ruby + VM), the Ebb web server, the Rev event toolkit. - - no event-like priority support at the moment (the ev priorities work - differently, but you can use idle watchers to get a similar effect). -AUTHOR +CONTRIBUTORS libev was written and designed by Marc Lehmann and Emanuele Giaquinta. The following people sent in patches or made other noteworthy - contributions to the design (if I forgot to include you, please shout - at me, it was an accident): + contributions to the design (for minor patches, see the Changes + file. If I forgot to include you, please shout at me, it was an + accident): W.C.A. Wijngaards Christopher Layne |