| 1 | libev is modelled (very losely) after libevent |
1 | libev is a high-performance event loop/event model with lots of features. |
| 2 | (http://monkey.org/~provos/libevent/), but aims to be faster and more |
2 | (see benchmark at http://libev.schmorp.de/bench.html) |
| 3 | correct, and also more featureful. Examples: |
|
|
| 4 | |
3 | |
| 5 | (comparisons relative to libevent-1.3e and libev-0.00) |
|
|
| 6 | |
4 | |
| 7 | - multiple watchers can wait for the same event without deregistering others, |
5 | ABOUT |
| 8 | both for file descriptors as well as signals. |
|
|
| 9 | (registering two read events on fd 10 and unregistering one will not |
|
|
| 10 | break the other) |
|
|
| 11 | |
6 | |
| 12 | - fork() is supported and can be handled |
7 | Homepage: http://software.schmorp.de/pkg/libev |
| 13 | (there is no way to recover from a fork when libevent is active) |
8 | Mailinglist: libev@lists.schmorp.de |
|
|
9 | http://lists.schmorp.de/cgi-bin/mailman/listinfo/libev |
|
|
10 | Library Documentation: http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod |
| 14 | |
11 | |
| 15 | - timers are handled as a priority queue (important operations are O(1)) |
12 | Libev is modelled (very losely) after libevent and the Event perl |
| 16 | (libevent uses a much less efficient but more complex red-black tree) |
13 | module, but is faster, scales better and is more correct, and also more |
|
|
14 | featureful. And also smaller. Yay. |
| 17 | |
15 | |
| 18 | - supports absolute (wallclock-based) timers in addition to relative ones, |
16 | Some of the specialties of libev not commonly found elsewhere are: |
| 19 | i.e. can schedule timers to occur after n seconds, or at a specific time. |
17 | |
|
|
18 | - extensive and detailed, readable documentation (not doxygen garbage). |
|
|
19 | - fully supports fork, can detect fork in various ways and automatically |
|
|
20 | re-arms kernel mechanisms that do not support fork. |
|
|
21 | - highly optimised select, poll, epoll, kqueue and event ports backends. |
|
|
22 | - filesystem object (path) watching (with optional linux inotify support). |
|
|
23 | - wallclock-based times (using absolute time, cron-like). |
|
|
24 | - relative timers/timeouts (handle time jumps). |
|
|
25 | - fast intra-thread communication between multiple |
|
|
26 | event loops (with optional fast linux eventfd backend). |
|
|
27 | - extremely easy to embed (fully documented, no dependencies, |
|
|
28 | autoconf supported but optional). |
|
|
29 | - very small codebase, no bloated library, simple code. |
|
|
30 | - fully extensible by being able to plug into the event loop, |
|
|
31 | integrate other event loops, integrate other event loop users. |
|
|
32 | - very little memory use (small watchers, small event loop data). |
|
|
33 | - optional C++ interface allowing method and function callbacks |
|
|
34 | at no extra memory or runtime overhead. |
|
|
35 | - optional Perl interface with similar characteristics (capable |
|
|
36 | of running Glib/Gtk2 on libev). |
|
|
37 | - support for other languages (multiple C++ interfaces, D, Ruby, |
|
|
38 | Python) available from third-parties. |
| 20 | |
39 | |
| 21 | - timers can be repeating (both absolute and relative ones) |
40 | Examples of programs that embed libev: the EV perl module, node.js, |
|
|
41 | auditd, rxvt-unicode, gvpe (GNU Virtual Private Ethernet), the |
|
|
42 | Deliantra MMORPG server (http://www.deliantra.net/), Rubinius (a |
|
|
43 | next-generation Ruby VM), the Ebb web server, the Rev event toolkit. |
| 22 | |
44 | |
| 23 | - detects time jumps and adjusts timers |
|
|
| 24 | (works for both forward and backward time jumps and also for absolute timers) |
|
|
| 25 | |
45 | |
| 26 | - can correctly remove timers while executing callbacks |
46 | CONTRIBUTORS |
| 27 | (libevent doesn't handle this reliably and can crash) |
|
|
| 28 | |
47 | |
| 29 | - race-free signal processing |
48 | libev was written and designed by Marc Lehmann and Emanuele Giaquinta. |
| 30 | (libevent may delay processing signals till after the next event) |
|
|
| 31 | |
49 | |
| 32 | - less calls to epoll_ctl |
50 | The following people sent in patches or made other noteworthy |
| 33 | (stopping and starting an io watcher between two loop iterations will now |
51 | contributions to the design (for minor patches, see the Changes |
| 34 | result in spuriois epoll_ctl calls) |
52 | file. If I forgot to include you, please shout at me, it was an |
|
|
53 | accident): |
| 35 | |
54 | |
| 36 | - usually less calls to gettimeofday and clock_gettime |
55 | W.C.A. Wijngaards |
| 37 | (libevent calls it on every timer event change, libev twice per iteration) |
56 | Christopher Layne |
|
|
57 | Chris Brody |
| 38 | |
58 | |
| 39 | - watchers use less memory |
|
|
| 40 | (libevent on amd64: 152 bytes, libev: <= 56 bytes) |
|
|
| 41 | |
|
|
| 42 | - library uses less memory |
|
|
| 43 | (libevent allocates large data structures wether used or not, libev |
|
|
| 44 | scales all its data structures dynamically) |
|
|
| 45 | |
|
|
| 46 | - no hardcoded arbitrary limits |
|
|
| 47 | (libevent contains an off-by-one bug and sometimes hardcodes a limit of |
|
|
| 48 | 32000 fds) |
|
|
| 49 | |
|
|
| 50 | - libev separates timer, signal and io watchers from each other |
|
|
| 51 | (libevent combines them, but with libev you can combine them yourself |
|
|
| 52 | by reusing the same callback and still save memory) |
|
|
| 53 | |
|
|
| 54 | - simpler design, backends are potentially much simpler |
|
|
| 55 | (in libevent, backends have to deal with watchers, thus the problems) |
|
|
| 56 | (epoll backend in libevent: 366 lines, libev: 90 lines, and more features) |
|
|
| 57 | |
|
|
| 58 | - libev handles EBADF gracefully by removing the offending fds. |
|
|
| 59 | |
|
|
| 60 | - doesn't rely on nonportable BSD header files. |
|
|
| 61 | |
|
|
| 62 | whats missing? |
|
|
| 63 | |
|
|
| 64 | - evdns, evhttp, bufferevent are missing, libev is only an even library at |
|
|
| 65 | the moment. |
|
|
| 66 | |
|
|
| 67 | - no priority support at the moment |
|
|
| 68 | |
|
|
| 69 | - kqueue, poll (libev currently implements epoll and select) |
|
|
| 70 | |
|
|
| 71 | - windows support (whats windows?) |
|
|
| 72 | |
|
|
