Created
February 5, 2019 14:40
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| #include <sys/time.h> | |
| #include <sys/resource.h> | |
| #include <sys/types.h> | |
| #include <sys/socket.h> | |
| #include <netdb.h> | |
| #include <stdio.h> | |
| #include <string.h> | |
| #include <resolv.h> | |
| #include <netdb.h> | |
| void set_max_fds(int count) { | |
| struct rlimit rlim; | |
| getrlimit(RLIMIT_NOFILE, &rlim); | |
| rlim.rlim_cur = count; | |
| setrlimit(RLIMIT_NOFILE, &rlim); | |
| } | |
| void try_resolve(char *msg) { | |
| struct addrinfo *res; | |
| printf("%s: resolving localhost:1234: ", msg); | |
| int r = getaddrinfo("localhost", "1234", NULL, &res); | |
| if (r != 0) { | |
| printf("%s\n", gai_strerror(r)); | |
| } else { | |
| printf("ok\n"); | |
| } | |
| } | |
| int main() { | |
| try_resolve("initial"); | |
| set_max_fds(3); | |
| try_resolve("with too many fds open"); | |
| set_max_fds(128); | |
| // uncomment this hack to make it work | |
| // h_errno = 0; | |
| try_resolve("with fds available again"); | |
| return 0; | |
| } |
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| use std::io; | |
| use std::net::ToSocketAddrs; | |
| use libc::{RLIMIT_NOFILE, getrlimit, rlimit, setrlimit}; | |
| fn set_max_fds(count: usize) -> io::Result<()> { | |
| let mut rlim = rlimit{ rlim_cur: 0, rlim_max: 0 }; | |
| unsafe { | |
| if getrlimit(RLIMIT_NOFILE, &mut rlim as *mut rlimit) != 0 { | |
| return Err(io::Error::last_os_error()); | |
| } | |
| rlim.rlim_cur = count as u64; | |
| if setrlimit(RLIMIT_NOFILE, &rlim as *const rlimit) != 0 { | |
| Err(io::Error::last_os_error()) | |
| } else { | |
| Ok(()) | |
| } | |
| } | |
| } | |
| fn try_resolve(msg: &str) { | |
| let addr = "localhost:1234"; | |
| println!("{}: resolving {}: {:?}", msg, addr, addr.to_socket_addrs()); | |
| } | |
| fn main() -> Result<(), Box<std::error::Error>> { | |
| try_resolve("initial"); | |
| set_max_fds(3)?; | |
| try_resolve("with too many fds open"); | |
| set_max_fds(128)?; | |
| // uncomment this hack to make it work | |
| // extern { fn __h_errno_location() -> *mut i32; } | |
| // unsafe { *__h_errno_location() = 0 } | |
| try_resolve("with fds available again"); | |
| Ok(()) | |
| } |
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