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use libc;
use std::io::{self, Result, Error, ErrorKind};
#[allow(dead_code)]
#[repr(C)]
#[derive(Copy, Clone)]
#[cfg(target_os = "linux")]
pub enum Sem {
GETPID = 11,
GETVAL = 12,
GETALL = 13,
GETZCNT = 15,
SETVAL = 16,
SETALL = 17,
}
#[allow(dead_code)]
#[repr(C)]
#[derive(Copy, Clone)]
#[cfg(target_os = "macos")]
pub enum Sem {
GETPID = 4,
GETVAL = 5,
GETALL = 6,
GETZCNT = 7,
SETVAL = 8,
SETALL = 9,
}
pub const SEM_NUM: u16 = 0;
pub const NSOPS: usize = 1;
pub const SEM_UNDO: i16 = 0x1000;
#[doc(hidden)]
pub trait IsMinusOne {
fn is_minus_one(&self) -> bool;
}
macro_rules! impl_is_minus_one {
($($t:ident)*) => ($(impl IsMinusOne for $t {
fn is_minus_one(&self) -> bool {
*self == -1
}
})*)
}
impl_is_minus_one! { i8 i16 i32 i64 isize }
pub fn cvt<T: IsMinusOne>(t: T) -> io::Result<T> {
if t.is_minus_one() {
Err(io::Error::last_os_error())
} else {
Ok(t)
}
}
#[derive(Debug)]
pub struct LockGuard {
id: libc::c_int,
}
impl Drop for LockGuard {
fn drop(&mut self) {
let _ = ProcessLock::unlock_by_id(self.id);
}
}
pub struct ProcessLock {
id: libc::c_int,
}
impl ProcessLock {
fn hash_code(name: &String) -> i32 {
let bytes = name.as_bytes();
let mut h = 0 as i32;
for byte in bytes {
h = h.wrapping_mul(31).wrapping_add(*byte as i32);
}
return h;
}
pub fn new(name: String, path_name: Option<String>) -> Result<ProcessLock> {
let path = path_name.clone().unwrap_or(String::from("."));
let code = Self::hash_code(&name);
unsafe {
let key = cvt(libc::ftok(path.as_bytes().as_ptr() as *mut i8, code))?;
let (id, is_create) = match cvt(libc::semget(key, 1024, 0o0666)) {
Ok(id) => {
(id, false)
}
Err(_) => {
(cvt(libc::semget(key, 1024, 0o0666 | libc::IPC_CREAT | libc::IPC_EXCL))?, true)
}
};
if is_create {
cvt(libc::semctl(id, SEM_NUM as i32, Sem::SETVAL as libc::c_int, 1))?;
}
return Ok(ProcessLock {
id: id,
})
}
}
pub fn trylock(&self) -> Result<Option<LockGuard>> {
let mut op = libc::sembuf {
sem_num: SEM_NUM,
sem_op: -1,
sem_flg: SEM_UNDO | libc::IPC_NOWAIT as i16,
};
unsafe {
let ret = libc::semop(self.id, &mut op as *mut libc::sembuf, NSOPS);
let err = io::Error::last_os_error();
if err.raw_os_error() == Some(libc::EAGAIN) {
return Ok(None);
} else if ret == -1 {
return Err(err);
}
Ok(Some(LockGuard {
id: self.id
}))
}
}
pub fn lock(&self) -> Result<LockGuard> {
unsafe {
let mut op = libc::sembuf {
sem_num: SEM_NUM,
sem_op: -1,
sem_flg: SEM_UNDO,
};
cvt(libc::semop(self.id, &mut op as *mut libc::sembuf, NSOPS))?;
Ok(LockGuard {
id: self.id
})
}
}
pub fn unlock(&self) -> Result<()> {
Self::unlock_by_id(self.id)
}
pub fn unlock_by_id(id: libc::c_int) -> Result<()> {
unsafe {
let mut op = libc::sembuf {
sem_num: SEM_NUM,
sem_op: 1,
sem_flg: SEM_UNDO,
};
cvt(libc::semop(id, &mut op, NSOPS))?;
Ok(())
}
}
pub fn destory(&mut self) -> Result<()> {
self.check_vaild()?;
unsafe {
cvt(libc::semctl(self.id, SEM_NUM as i32, libc::IPC_RMID))?;
self.id = -1;
}
Ok(())
}
pub fn check_vaild(&self) -> Result<bool> {
if self.id == -1 {
return Err(Error::new(ErrorKind::InvalidData, "no vaild"));
}
return Ok(true);
}
}