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1.11 |
libev is a high-performance event loop/event model with lots of features. |
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1.9 |
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It is modelled (very losely) after libevent |
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(http://monkey.org/~provos/libevent/) and the Event perl module, but aims |
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to be faster and more correct, and also more featureful. |
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DIFFERENCES AND COMPARISON TO LIBEVENT: |
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1.1 |
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root |
1.10 |
(comparisons relative to libevent-1.3e and libev-0.00, see also the benchmark |
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at http://libev.schmorp.de/bench.html). |
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1.5 |
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1.4 |
- multiple watchers can wait for the same event without deregistering others, |
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both for file descriptors as well as signals. |
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root |
1.2 |
(registering two read events on fd 10 and unregistering one will not |
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root |
1.9 |
break the other). |
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root |
1.2 |
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- fork() is supported and can be handled |
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root |
1.9 |
(there is no way to recover from a fork when libevent is active). |
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root |
1.2 |
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root |
1.7 |
- timers are handled as a priority queue (important operations are O(1)) |
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root |
1.9 |
(libevent uses a much less efficient but more complex red-black tree). |
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1.2 |
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- supports absolute (wallclock-based) timers in addition to relative ones, |
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i.e. can schedule timers to occur after n seconds, or at a specific time. |
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root |
1.9 |
- timers can be repeating (both absolute and relative ones). |
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1.2 |
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- detects time jumps and adjusts timers |
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root |
1.9 |
(works for both forward and backward time jumps and also for absolute timers). |
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root |
1.2 |
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root |
1.3 |
- race-free signal processing |
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root |
1.9 |
(libevent may delay processing signals till after the next event). |
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root |
1.3 |
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root |
1.2 |
- less calls to epoll_ctl |
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(stopping and starting an io watcher between two loop iterations will now |
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root |
1.9 |
result in spuriois epoll_ctl calls). |
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root |
1.2 |
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- usually less calls to gettimeofday and clock_gettime |
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root |
1.9 |
(libevent calls it on every timer event change, libev twice per iteration). |
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root |
1.2 |
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- watchers use less memory |
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root |
1.9 |
(libevent on amd64: 152 bytes, libev: <= 56 bytes). |
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1.2 |
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- library uses less memory |
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(libevent allocates large data structures wether used or not, libev |
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1.9 |
scales all its data structures dynamically). |
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1.2 |
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- no hardcoded arbitrary limits |
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(libevent contains an off-by-one bug and sometimes hardcodes a limit of |
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1.9 |
32000 fds). |
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root |
1.2 |
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- libev separates timer, signal and io watchers from each other |
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(libevent combines them, but with libev you can combine them yourself |
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root |
1.9 |
by reusing the same callback and still save memory). |
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root |
1.2 |
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- simpler design, backends are potentially much simpler |
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(in libevent, backends have to deal with watchers, thus the problems) |
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root |
1.9 |
(epoll backend in libevent: 366 lines, libev: 90 lines, and more features). |
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root |
1.2 |
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root |
1.6 |
- libev handles EBADF gracefully by removing the offending fds. |
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1.8 |
- doesn't rely on nonportable BSD header files. |
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root |
1.9 |
- a event.h compatibility header exists, and can be used to run a wide |
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range of libevent programs unchanged (such as evdns.c). |
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root |
1.13 |
- win32 compatibility for the core parts. |
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- the event core library (ev and event layer) compiles and works both as |
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C and C++. |
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root |
1.2 |
whats missing? |
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root |
1.14 |
- no event-like priority support at the moment (the ev priorities |
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are not yet finished and work differently, but you cna use idle watchers |
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to get a similar effect). |
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root |
1.2 |
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78 |
root |
1.1 |
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