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Revision: 1.17
Committed: Mon Nov 12 05:40:55 2007 UTC (16 years, 11 months ago) by root
Branch: MAIN
CVS Tags: rel-0_9
Changes since 1.16: +9 -0 lines
Log Message:
applied patches by W.C.A. Wijngaards, changed env variable handling

File Contents

# Content
1 Homepage: http://software.schmorp.de/pkg/libev
2 E-Mail: libev@schmorp.de
3
4 libev is a high-performance event loop/event model with lots of features.
5
6 It is modelled (very losely) after libevent
7 (http://monkey.org/~provos/libevent/) and the Event perl module, but aims
8 to be faster and more correct, and also more featureful.
9
10 DIFFERENCES AND COMPARISON TO LIBEVENT:
11
12 (comparisons relative to libevent-1.3e and libev-0.00, see also the benchmark
13 at http://libev.schmorp.de/bench.html).
14
15 - multiple watchers can wait for the same event without deregistering others,
16 both for file descriptors as well as signals.
17 (registering two read events on fd 10 and unregistering one will not
18 break the other).
19
20 - fork() is supported and can be handled
21 (there is no way to recover from a fork when libevent is active).
22
23 - timers are handled as a priority queue (important operations are O(1))
24 (libevent uses a much less efficient but more complex red-black tree).
25
26 - supports absolute (wallclock-based) timers in addition to relative ones,
27 i.e. can schedule timers to occur after n seconds, or at a specific time.
28
29 - timers can be repeating (both absolute and relative ones).
30
31 - detects time jumps and adjusts timers
32 (works for both forward and backward time jumps and also for absolute timers).
33
34 - race-free signal processing
35 (libevent may delay processing signals till after the next event).
36
37 - less calls to epoll_ctl
38 (stopping and starting an io watcher between two loop iterations will now
39 result in spuriois epoll_ctl calls).
40
41 - usually less calls to gettimeofday and clock_gettime
42 (libevent calls it on every timer event change, libev twice per iteration).
43
44 - watchers use less memory
45 (libevent on amd64: 152 bytes, libev: <= 56 bytes).
46
47 - library uses less memory
48 (libevent allocates large data structures wether used or not, libev
49 scales all its data structures dynamically).
50
51 - no hardcoded arbitrary limits
52 (libevent contains an off-by-one bug and sometimes hardcodes a limit of
53 32000 fds).
54
55 - libev separates timer, signal and io watchers from each other
56 (libevent combines them, but with libev you can combine them yourself
57 by reusing the same callback and still save memory).
58
59 - simpler design, backends are potentially much simpler
60 (in libevent, backends have to deal with watchers, thus the problems)
61 (epoll backend in libevent: 366 lines, libev: 90 lines, and more features).
62
63 - libev handles EBADF gracefully by removing the offending fds.
64
65 - doesn't rely on nonportable BSD header files.
66
67 - a event.h compatibility header exists, and can be used to run a wide
68 range of libevent programs unchanged (such as evdns.c).
69
70 - win32 compatibility for the core parts.
71
72 - the event core library (ev and event layer) compiles and works both as
73 C and C++.
74
75 whats missing?
76
77 - no event-like priority support at the moment (the ev priorities
78 are not yet finished and work differently, but you can use idle watchers
79 to get a similar effect).
80
81 AUTHOR
82
83 libev was written and designed by Marc Lehmann and Emanuele Giaquinta.
84
85 The following people sent in patches or made other noteworthy
86 contributions (if I forgot to include you, please shout at me, it was an
87 accident):
88
89 W.C.A. Wijngaards
90 Christopher Layne
91 Chris Brody
92