Created
July 26, 2018 16:16
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test whether closing an fd which is being waited on in epoll_wait causes the wait to wake up (it doesn't)
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const std = @import("std"); | |
pub fn main() !void { | |
const epollfd = blk: { | |
const rc = std.os.linux.epoll_create1(std.os.linux.EPOLL_CLOEXEC); | |
const err = std.os.linux.getErrno(rc); | |
if (err != 0) return error.EpollCreateFailed; | |
break :blk @intCast(i32, rc); | |
}; | |
defer std.os.close(epollfd); | |
var pipe: [2]i32 = undefined; | |
{ | |
const rc = std.os.linux.pipe2(&pipe, std.os.linux.O_CLOEXEC); | |
const err = std.os.linux.getErrno(rc); | |
if (err != 0) return error.PipeCreateFailed; | |
} | |
var ev: std.os.linux.epoll_event = undefined; | |
ev.events = std.os.linux.EPOLLIN | std.os.linux.EPOLLET; | |
ev.data.fd = pipe[0]; | |
{ | |
const rc = std.os.linux.epoll_ctl(epollfd, std.os.linux.EPOLL_CTL_ADD, pipe[0], &ev); | |
const err = std.os.linux.getErrno(rc); | |
if (err != 0) return error.EpollCtlFailed; | |
} | |
const thread = try std.os.spawnThread(pipe[0], threadStart); | |
var events: [10]std.os.linux.epoll_event = undefined; | |
const nfds = blk: { | |
std.debug.warn("epoll wait\n"); | |
const rc = std.os.linux.epoll_wait(epollfd, &events, @intCast(u32, events.len), -1); | |
std.debug.warn("epoll wakeup\n"); | |
const err = std.os.linux.getErrno(rc); | |
if (err != 0) return error.EpollWaitFailed; | |
break :blk rc; | |
}; | |
if (nfds != 1) return error.NotExactly1FileDescriptor; | |
std.debug.assert(events[0].data.fd == pipe[0]); | |
thread.wait(); | |
} | |
fn threadStart(fd: i32) void { | |
std.os.time.sleep(1, 0); | |
std.debug.warn("close fd\n"); | |
std.os.close(fd); | |
} |
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epoll wait | |
close fd | |
^C |
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execve("./test", ["./test"], 0x7fff311ff208 /* 122 vars */) = 0 | |
epoll_create1(EPOLL_CLOEXEC) = 3 | |
pipe2([4, 5], O_CLOEXEC) = 0 | |
epoll_ctl(3, EPOLL_CTL_ADD, 4, {EPOLLIN|EPOLLET, {u32=4, u64=4}}) = 0 | |
mmap(NULL, 8388608, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_GROWSDOWN, -1, 0) = 0x7fd082ed9000 | |
clone(child_stack=0x7fd0836d8fd8, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID|0x400000, parent_tidptr=0x7fd0836d8fe4, child_tidptr=0x7fd0836d8fe4) = 13547 | |
strace: Process 13547 attached | |
[pid 13546] write(2, "epoll wait\n", 11epoll wait | |
<unfinished ...> | |
[pid 13547] nanosleep({tv_sec=1, tv_nsec=0}, <unfinished ...> | |
[pid 13546] <... write resumed> ) = 11 | |
[pid 13546] epoll_wait(3, <unfinished ...> | |
[pid 13547] <... nanosleep resumed> 0x7fd0836d8f20) = 0 | |
[pid 13547] write(2, "close fd\n", 9close fd | |
) = 9 | |
[pid 13547] close(4) = 0 | |
[pid 13547] exit(0) = ? | |
[pid 13547] +++ exited with 0 +++ | |
^Cstrace: Process 13546 detached |
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