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Revision: 1.8
Committed: Thu Nov 1 11:55:54 2007 UTC (17 years ago) by root
Branch: MAIN
Changes since 1.7: +5 -2 lines
Log Message:
*** empty log message ***

File Contents

# Content
1 libev is modelled (very losely) after libevent
2 (http://monkey.org/~provos/libevent/), but aims to be faster and more
3 correct, and also more featureful. Examples:
4
5 (comparisons relative to libevent-1.3e and libev-0.00)
6
7 - multiple watchers can wait for the same event without deregistering others,
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
12 - fork() is supported and can be handled
13 (there is no way to recover from a fork when libevent is active)
14
15 - timers are handled as a priority queue (important operations are O(1))
16 (libevent uses a much less efficient but more complex red-black tree)
17
18 - supports absolute (wallclock-based) timers in addition to relative ones,
19 i.e. can schedule timers to occur after n seconds, or at a specific time.
20
21 - timers can be repeating (both absolute and relative ones)
22
23 - detects time jumps and adjusts timers
24 (works for both forward and backward time jumps and also for absolute timers)
25
26 - can correctly remove timers while executing callbacks
27 (libevent doesn't handle this reliably and can crash)
28
29 - race-free signal processing
30 (libevent may delay processing signals till after the next event)
31
32 - less calls to epoll_ctl
33 (stopping and starting an io watcher between two loop iterations will now
34 result in spuriois epoll_ctl calls)
35
36 - usually less calls to gettimeofday and clock_gettime
37 (libevent calls it on every timer event change, libev twice per iteration)
38
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