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Comparing libev/ev_epoll.c (file contents):
Revision 1.16 by root, Sun Nov 4 18:29:44 2007 UTC vs.
Revision 1.32 by root, Thu Dec 13 16:52:50 2007 UTC

… …
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */ 30 */
31 31
32/*
33 * general notes about epoll:
34 *
35 * a) epoll silently removes fds from the fd set. as nothing tells us
36 * that an fd has been removed otherwise, we have to continually
37 * "rearm" fds that we suspect *might* have changed (same
38 * problem with kqueue, but much less costly there).
39 * b) the fact that ADD != MOD creates a lot of extra syscalls due to a)
40 * and seems not to have any advantage.
41 * c) the inability to handle fork or file descriptors (think dup)
42 * limits the applicability over poll, so this is not a generic
43 * poll replacement.
44 *
45 * lots of "weird code" and complication handling in this file is due
46 * to these design problems with epoll, as we try very hard to avoid
47 * epoll_ctl syscalls for common usage patterns.
48 */
49
32#include <sys/epoll.h> 50#include <sys/epoll.h>
33 51
34static void 52static void
35epoll_modify (EV_P_ int fd, int oev, int nev) 53epoll_modify (EV_P_ int fd, int oev, int nev)
36{ 54{
37 int mode = nev ? oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD : EPOLL_CTL_DEL; 55 struct epoll_event ev;
38 56
39 struct epoll_event ev; 57 /*
58 * we handle EPOLL_CTL_DEL by ignoring it here
59 * on the assumption that the fd is gone anyways
60 * if that is wrong, we have to handle the spurious
61 * event in epoll_poll.
62 */
63 if (!nev)
64 return;
65
40 ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */ 66 ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */
41 ev.events =
42 (nev & EV_READ ? EPOLLIN : 0) 67 ev.events = (nev & EV_READ ? EPOLLIN : 0)
43 | (nev & EV_WRITE ? EPOLLOUT : 0); 68 | (nev & EV_WRITE ? EPOLLOUT : 0);
44 69
45 epoll_ctl (epoll_fd, mode, fd, &ev); 70 if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev)))
71 return;
72
73 if (expect_true (errno == ENOENT))
74 {
75 /* on ENOENT the fd went away, so try to do the right thing */
76 if (!nev)
77 return;
78
79 if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev))
80 return;
81 }
82 else if (expect_true (errno == EEXIST))
83 {
84 /* on EEXIST we ignored a previous DEL */
85 if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev))
86 return;
87 }
88
89 fd_kill (EV_A_ fd);
46} 90}
47 91
48static void 92static void
49epoll_poll (EV_P_ ev_tstamp timeout) 93epoll_poll (EV_P_ ev_tstamp timeout)
50{ 94{
51 int eventcnt = epoll_wait (epoll_fd, epoll_events, epoll_eventmax, ceil (timeout * 1000.));
52 int i; 95 int i;
96 int eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.));
53 97
54 if (eventcnt < 0) 98 if (expect_false (eventcnt < 0))
99 {
100 if (errno != EINTR)
101 syserr ("(libev) epoll_wait");
102
55 return; 103 return;
104 }
56 105
57 for (i = 0; i < eventcnt; ++i) 106 for (i = 0; i < eventcnt; ++i)
58 fd_event ( 107 {
59 EV_A_ 108 struct epoll_event *ev = epoll_events + i;
60 epoll_events [i].data.u64, 109
110 int fd = ev->data.u64;
61 (epoll_events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) 111 int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0)
62 | (epoll_events [i].events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0) 112 | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0);
63 ); 113 int want = anfds [fd].events;
114
115 if (expect_false (got & ~want))
116 {
117 /* we received an event but are not interested in it, try mod or del */
118 ev->events = (want & EV_READ ? EPOLLIN : 0)
119 | (want & EV_WRITE ? EPOLLOUT : 0);
120
121 epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev);
122 }
123
124 fd_event (EV_A_ fd, got);
125 }
64 126
65 /* if the receive array was full, increase its size */ 127 /* if the receive array was full, increase its size */
66 if (expect_false (eventcnt == epoll_eventmax)) 128 if (expect_false (eventcnt == epoll_eventmax))
67 { 129 {
68 free (epoll_events); 130 ev_free (epoll_events);
69 epoll_eventmax = array_roundsize (epoll_events, epoll_eventmax << 1); 131 epoll_eventmax = array_nextsize (sizeof (struct epoll_event), epoll_eventmax, epoll_eventmax + 1);
70 epoll_events = malloc (sizeof (struct epoll_event) * epoll_eventmax); 132 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
71 } 133 }
72} 134}
73 135
74static int 136int inline_size
75epoll_init (EV_P_ int flags) 137epoll_init (EV_P_ int flags)
76{ 138{
77 epoll_fd = epoll_create (256); 139 backend_fd = epoll_create (256);
78 140
79 if (epoll_fd < 0) 141 if (backend_fd < 0)
80 return 0; 142 return 0;
81 143
82 fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); 144 fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
83 145
84 method_fudge = 1e-3; /* needed to compensate for epoll returning early */ 146 backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */
85 method_modify = epoll_modify; 147 backend_modify = epoll_modify;
86 method_poll = epoll_poll; 148 backend_poll = epoll_poll;
87 149
88 epoll_eventmax = 64; /* intiial number of events receivable per poll */ 150 epoll_eventmax = 64; /* intiial number of events receivable per poll */
89 epoll_events = malloc (sizeof (struct epoll_event) * epoll_eventmax); 151 epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax);
90 152
91 return EVMETHOD_EPOLL; 153 return EVBACKEND_EPOLL;
92} 154}
93 155
94static void 156void inline_size
95epoll_destroy (EV_P) 157epoll_destroy (EV_P)
96{ 158{
97 close (epoll_fd);
98
99 free (epoll_events); 159 ev_free (epoll_events);
100} 160}
101 161
102static void 162void inline_size
103epoll_fork (EV_P) 163epoll_fork (EV_P)
104{ 164{
105 epoll_fd = epoll_create (256); 165 close (backend_fd);
166
167 while ((backend_fd = epoll_create (256)) < 0)
168 syserr ("(libev) epoll_create");
169
106 fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); 170 fcntl (backend_fd, F_SETFD, FD_CLOEXEC);
107 171
108 fd_rearm_all (EV_A); 172 fd_rearm_all (EV_A);
109} 173}
110 174

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