我有一个C++程序和一个Rust程序，我已经成功地让它们通过POSIX共享内存(C++和rust)进行了交谈.
我现在试图做的是使它们同步.我已经设法使用原子布尔创建了一个工作但效率低下的原始系统(在 rust 面like this上创建了AtomicBool).
然而，我真的很想使用互斥/condvar在线程之间进行同步，这就是我被困住的地方.
我似乎能够初始化它的C++端，几乎逐字跟随this example个字.
我试着把它直接翻译成铁 rust :
let raw_shm = shm.get_shm();
let mut mtx_attrs = MaybeUninit::<nix::libc::pthread_mutexattr_t>::uninit();
if unsafe { nix::libc::pthread_mutexattr_init(mtx_attrs.as_mut_ptr()) } != 0 {
panic!("failed to create mtx_attrs");
};
let mtx_attrs = unsafe { mtx_attrs.assume_init() };
let mut cond_attrs = MaybeUninit::<nix::libc::pthread_condattr_t>::uninit();
if unsafe { nix::libc::pthread_condattr_init(cond_attrs.as_mut_ptr()) } != 0 {
panic!("failed to create cond_attrs");
};
let cond_attrs = unsafe { cond_attrs.assume_init() };
if unsafe {
nix::libc::pthread_mutexattr_setpshared(
&mtx_attrs as *const _ as *mut _,
PTHREAD_PROCESS_SHARED,
)
} != 0
{
panic!("failed to set mtx as process shared");
};
if unsafe {
nix::libc::pthread_condattr_setpshared(
&cond_attrs as *const _ as *mut _,
PTHREAD_PROCESS_SHARED,
)
} != 0
{
panic!("failed to set cond as process shared");
};
// I know that these offsets are correct, having used `offsetof` on the C++ side
let mtx_start = unsafe { &raw_shm.as_slice()[3110416] };
let mtx = unsafe { &*(mtx_start as *const _ as *const pthread_mutex_t) };
let cond_start = unsafe { &raw_shm.as_slice()[3110440] };
let cond = unsafe { &*(cond_start as *const _ as *const pthread_mutex_t) };
if unsafe {
nix::libc::pthread_mutex_init(&mtx as *const _ as *mut _, &mtx_attrs as *const _ as *mut _)
} != 0
{
panic!("failed to init mtx");
};
if unsafe {
nix::libc::pthread_cond_init(
&cond as *const _ as *mut _,
&cond_attrs as *const _ as *mut _,
)
} != 0
{
panic!("failed to init cond");
};
所有这些都以返回值0传递...到目前一切尚好.
我现在可以通过以下两种方式之一进行测试:
- 我可以让这个简单的C++程序继续运行，并让它停止在condvar处等待:
if (pthread_mutex_lock(&shmp->mutex) != 0)
throw("Error locking mutex");
if (pthread_cond_wait(&shmp->condition, &shmp->mutex) != 0)
throw("Error waiting for condition variable");
在铁 rust 中:
let sig = unsafe { nix::libc::pthread_cond_signal(&cond as *const _ as *mut _) };
dbg!(sig);
尽管返回0(即成功)，但我的C++程序并未释放超过condvar；它仍在等待，就好像从未收到信号一样.
- 我可以设置另一个简单的C++程序，它在循环中无休止地发出条件变量的信号:
for (unsigned int count = 0;; count++) {
if (pthread_cond_signal(condition) != 0)
throw("Error")
// sleep for a bit
}
然后在Rust 的时候，大概是这样:
loop {
if unsafe { nix::libc::pthread_mutex_lock(&mtx as *const _ as *mut _) } > 0 {
panic!("Failed to acquire lock")
};
if unsafe {
nix::libc::pthread_cond_wait(&cond as *const _ as *mut _, &mtx as *const _ as *mut _)
} > 0
{
panic!("Failed to acquire lock")
};
}
这样做，锁定互斥锁的调用是成功的，但我在pthread_cond_wait定义的here上得到了EINVAL，我似乎无法纠正...
我觉得我快到了...你有什么 idea 让它发挥作用吗？(这主要是一个概念验证).