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| 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 | |
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32 | /* |
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33 | * general notes about epoll: |
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34 | * |
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35 | * a) epoll silently removes fds from the fd set. as nothing tells us |
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36 | * that an fd has been removed otherwise, we have to continually |
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37 | * "rearm" fds that we suspect *might* have changed (same |
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38 | * problem with kqueue, but much less costly there). |
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39 | * b) the fact that ADD != MOD creates a lot of extra syscalls due to a) |
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40 | * and seems not to have any advantage. |
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41 | * c) the inability to handle fork or file descriptors (think dup) |
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42 | * limits the applicability over poll, so this is not a generic |
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43 | * poll replacement. |
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44 | * |
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45 | * lots of "weird code" and complication handling in this file is due |
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46 | * to these design problems with epoll, as we try very hard to avoid |
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47 | * epoll_ctl syscalls for common usage patterns. |
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48 | */ |
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49 | |
| 32 | #include <sys/epoll.h> |
50 | #include <sys/epoll.h> |
| 33 | |
51 | |
| 34 | static void |
52 | static void |
| 35 | epoll_modify (EV_P_ int fd, int oev, int nev) |
53 | epoll_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 | /* |
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58 | * we handle EPOLL_CTL_DEL by ignoring it here |
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59 | * on the assumption that the fd is gone anyways |
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60 | * if that is wrong, we have to handle the spurious |
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61 | * event in epoll_poll. |
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62 | */ |
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63 | if (!nev) |
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64 | return; |
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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 = |
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| 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 | if (expect_false (epoll_ctl (backend_fd, mode, fd, &ev))) |
70 | if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev))) |
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71 | return; |
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72 | |
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73 | if (expect_true (errno == ENOENT)) |
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74 | { |
| 46 | if (errno != ENOENT /* on ENOENT the fd went away, so try to do the right thing */ |
75 | /* on ENOENT the fd went away, so try to do the right thing */ |
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76 | if (!nev) |
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77 | return; |
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78 | |
| 47 | || (nev && epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev))) |
79 | if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)) |
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80 | return; |
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81 | } |
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82 | else if (expect_true (errno == EEXIST)) |
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83 | { |
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84 | /* on EEXIST we ignored a previous DEL */ |
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85 | if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev)) |
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86 | return; |
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87 | } |
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88 | |
| 48 | fd_kill (EV_A_ fd); |
89 | fd_kill (EV_A_ fd); |
| 49 | } |
90 | } |
| 50 | |
91 | |
| 51 | static void |
92 | static void |
| 52 | epoll_poll (EV_P_ ev_tstamp timeout) |
93 | epoll_poll (EV_P_ ev_tstamp timeout) |
| 53 | { |
94 | { |
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| 61 | |
102 | |
| 62 | return; |
103 | return; |
| 63 | } |
104 | } |
| 64 | |
105 | |
| 65 | for (i = 0; i < eventcnt; ++i) |
106 | for (i = 0; i < eventcnt; ++i) |
| 66 | fd_event ( |
107 | { |
| 67 | EV_A_ |
108 | struct epoll_event *ev = epoll_events + i; |
| 68 | epoll_events [i].data.u64, |
109 | |
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110 | int fd = ev->data.u64; |
| 69 | (epoll_events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) |
111 | int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) |
| 70 | | (epoll_events [i].events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0) |
112 | | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0); |
| 71 | ); |
113 | int want = anfds [fd].events; |
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114 | |
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115 | if (expect_false (got & ~want)) |
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116 | { |
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117 | /* we received an event but are not interested in it, try mod or del */ |
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118 | ev->events = (want & EV_READ ? EPOLLIN : 0) |
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119 | | (want & EV_WRITE ? EPOLLOUT : 0); |
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120 | |
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121 | epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev); |
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122 | } |
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123 | |
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124 | fd_event (EV_A_ fd, got); |
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125 | } |
| 72 | |
126 | |
| 73 | /* if the receive array was full, increase its size */ |
127 | /* if the receive array was full, increase its size */ |
| 74 | if (expect_false (eventcnt == epoll_eventmax)) |
128 | if (expect_false (eventcnt == epoll_eventmax)) |
| 75 | { |
129 | { |
| 76 | ev_free (epoll_events); |
130 | ev_free (epoll_events); |
