| 1 | /* |
1 | /* |
| 2 | * libev epoll fd activity backend |
2 | * libev epoll fd activity backend |
| 3 | * |
3 | * |
| 4 | * Copyright (c) 2007,2008,2009 Marc Alexander Lehmann <libev@schmorp.de> |
4 | * Copyright (c) 2007,2008,2009,2010 Marc Alexander Lehmann <libev@schmorp.de> |
| 5 | * All rights reserved. |
5 | * All rights reserved. |
| 6 | * |
6 | * |
| 7 | * Redistribution and use in source and binary forms, with or without modifica- |
7 | * Redistribution and use in source and binary forms, with or without modifica- |
| 8 | * tion, are permitted provided that the following conditions are met: |
8 | * tion, are permitted provided that the following conditions are met: |
| 9 | * |
9 | * |
| … | |
… | |
| 47 | * b) the fact that ADD != MOD creates a lot of extra syscalls due to a) |
47 | * b) the fact that ADD != MOD creates a lot of extra syscalls due to a) |
| 48 | * and seems not to have any advantage. |
48 | * and seems not to have any advantage. |
| 49 | * c) the inability to handle fork or file descriptors (think dup) |
49 | * c) the inability to handle fork or file descriptors (think dup) |
| 50 | * limits the applicability over poll, so this is not a generic |
50 | * limits the applicability over poll, so this is not a generic |
| 51 | * poll replacement. |
51 | * poll replacement. |
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52 | * d) epoll doesn't work the same as select with many file descriptors |
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53 | * (such as files). while not critical, no other advanced interface |
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54 | * seems to share this (rather non-unixy) limitation. |
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55 | * e) epoll claims to be embeddable, but in practise you never get |
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56 | * a ready event for the epoll fd. |
| 52 | * |
57 | * |
| 53 | * lots of "weird code" and complication handling in this file is due |
58 | * lots of "weird code" and complication handling in this file is due |
| 54 | * to these design problems with epoll, as we try very hard to avoid |
59 | * to these design problems with epoll, as we try very hard to avoid |
| 55 | * epoll_ctl syscalls for common usage patterns and handle the breakage |
60 | * epoll_ctl syscalls for common usage patterns and handle the breakage |
| 56 | * ensuing from receiving events for closed and otherwise long gone |
61 | * ensuing from receiving events for closed and otherwise long gone |
