我有一个从各种输入生成哈希的函数。我想存储一个这样的哈希，Arc<[u8; 16]>以便我可以在线程和结构之间共享它。之前，我将它存储为Vec<u8>，通过通道传递，然后将其转换为[u8; 16]本地。显然效率低下，因此Arc<[u8; 16]>. 但是当我进行转换时，我得到了这样的错误：
error[E0277]: `std::sync::mpsc::Sender<Header<'a, Body<'a>>>` cannot be shared between threads safely
--> src/lib.rs:182:13
|
182 | spawn(move || {
| ^^^^^ `std::sync::mpsc::Sender<Header<'a, Body<'a>>>` cannot be shared between threads safely
|
= help: within `CreatorPipeline<Header<'a, Body<'a>>, std::sync::Arc<[u8; 16]>, (std::sync::Arc<[u8; 16]>, std::path::PathBuf, u64), (std::vec::Vec<u8>, u64, std::vec::Vec<u8>), Block, Body<'a>>`, the trait `std::marker::Sync` is not implemented for `std::sync::mpsc::Sender<Header<'a, Body<'a>>>`
= note: required because it appears within the type `(std::sync::mpsc::Sender<Header<'a, Body<'a>>>, std::sync::mpsc::Receiver<Header<'a, Body<'a>>>)`
= note: required because it appears within the type `CreatorPipeline<Header<'a, Body<'a>>, std::sync::Arc<[u8; 16]>, (std::sync::Arc<[u8; 16]>, std::path::PathBuf, u64), (std::vec::Vec<u8>, u64, std::vec::Vec<u8>), Block, Body<'a>>`
= note: required because of the requirements on the impl of `std::marker::Send` for `&CreatorPipeline<Header<'a, Body<'a>>, std::sync::Arc<[u8; 16]>, (std::sync::Arc<[u8; 16]>, std::path::PathBuf, u64), (std::vec::Vec<u8>, u64, std::vec::Vec<u8>), Block, Body<'a>>`
= note: required because it appears within the type `[closure@src/lib.rs:182:19: 232:14 file:std::path::PathBuf, self:&CreatorPipeline<Header<'a, Body<'a>>, std::sync::Arc<[u8; 16]>, (std::sync::Arc<[u8; 16]>, std::path::PathBuf, u64), (std::vec::Vec<u8>, u64, std::vec::Vec<u8>), Block, Body<'a>>, tx_main:std::sync::mpsc::Sender<std::sync::Arc<[u8; 16]>>, tx_input:std::sync::mpsc::Sender<(std::sync::Arc<[u8; 16]>, std::path::PathBuf, u64)>, tx_fd:std::sync::mpsc::Sender<(std::vec::Vec<u8>, u64, std::vec::Vec<u8>)>]`
= note: required by `rayon_core::spawn::spawn`
还有11个这样的错误。的所有一些变化Foo cannot be shared between threads safely。这是所有错误的要点。
这是我的代码片段：
...
// File creation pipeline
pub struct CreatorPipeline<A, B, C, D, E, F> {
magic: Arc<[u8; 8]>,
rec_set_id: Arc<RwLock<Option<&'static [u8; 16]>>>,
writes: (Sender<A>, Receiver<A>), // A: Header<Body>
main: (Sender<B>, Receiver<B>), // B: Arc<[u8; 16]>
input: (Sender<C>, Receiver<C>), // C: (Arc<[u8; 16]>, File)
body: (Sender<F>, Receiver<F>), // F: Body
file_description: (Sender<D>, Receiver<D>), // D: (Arc<[u8; 16]>, u64, Vec<u8>)
recovery: (Sender<E>, Receiver<E>), // E: Block
}
// Creation pipeline methods
impl<'a>
CreatorPipeline<
Header<Body<'a>>, // writes Packet
Arc<[u8; 16]>, // main file_id
(Arc<[u8; 16]>, PathBuf, u64), // input (file_id, file, length)
(Vec<u8>, u64, Vec<u8>), // file_description (name, length, hash_16k)
Block, // recovery Block
Body<'a>, // packet Body
>
{
...
// First Stage: Create file ids and partial bodies for FileDescription. Send
// file ids, partial bodies and file readers to the correct channels.
fn create_file_id(&self, files: Vec<PathBuf>) -> Result<(), ExitFailure> {
let (tx_main, _) = &self.main; // sender for create_main()
let (tx_input, _) = &self.input; // sender for create_input()
let (tx_fd, _) = &self.file_description; // sender for create_fd()
for file in files {
let tx_main = tx_main.clone();
let tx_input = tx_input.clone();
let tx_fd = tx_fd.clone();
// Spawn thread
spawn(move || {
let mut reader = File::open(&file)
.with_context(|_| format!("Could not open file {}", file.display()))
.unwrap();
// Get filename from path
let name = file
.file_stem()
.unwrap()
.to_string_lossy()
.into_owned()
.into_bytes();
let length = {
let metadata = metadata(&file).unwrap();
metadata.len()
};
// Hash first 16k of the file
let hash_16k = {
let mut hasher_16k = Md5::new();
let mut buffer = [0; 16384];
reader.read(&mut buffer).unwrap();
for byte in buffer.iter() {
hasher_16k.input([byte.clone()]);
}
let result = hasher_16k.result();
let hash_16k = result.as_slice().to_owned();
hash_16k
};
// Generate File ID
let file_id = {
let mut hasher_file_id = Md5::new();
hasher_file_id.input(&hash_16k);
hasher_file_id.input(&length.to_le_bytes());
hasher_file_id.input(&name);
let file_id = hasher_file_id.result().to_vec();
let file_id = self.convert_to_byte_array(file_id);
Arc::new(file_id) // Problem line
};
// Partial FileDescription (name, length, hash_16k)
let partial_body = (name, length, hash_16k);
// sender for channels
tx_main.send(Arc::clone(&file_id)).unwrap();
tx_input.send((Arc::clone(&file_id), file, length)).unwrap();
tx_fd.send(partial_body).unwrap();
});
}
Ok(())
}
...
}
编辑：忘了提到我使用的是 2018 版稳定版。