Struct io_partition::PartitionMutex

pub struct PartitionMutex<T: Read + Seek> { /* fields omitted */ }

A PartitionMutex allow you to refer to a part of the file. It consume the input file.

As the input file is an Arc<Mutex<_>>, multiple PartitionMutex can be created by file, and PartitionMutex can be cloned.

The input offset is the first byte that will be accessible. The user of the PartitionMutex won't be able to seek before it, and it will be considered the offset 0 of the PartitionMutex The input lenght is the number of byte that can be read with this PartitionMutex. The last readable byte from the input file is input_offset + input_len

It is possible to lock the mutex with PartitionMutex::lock. You need to take care when using it, or a panic may occur. Please read the documentation of the function.

Examples

use std::io::{Cursor, Read, Seek, SeekFrom};
use io_partition::PartitionMutex;
use std::sync::{Mutex, Arc};
use std::thread;

let mut some_value = (0..100).collect::<Vec<u8>>();
let some_file = Arc::new(Mutex::new(Cursor::new(some_value)));

let mut first_partition = PartitionMutex::new(some_file.clone(), 10, 20).unwrap();
let mut second_partition = PartitionMutex::new(some_file.clone(), 40, 30).unwrap();

let mut buf = [0];

first_partition.seek(SeekFrom::Start(10)).unwrap();
second_partition.seek(SeekFrom::Start(5)).unwrap();
first_partition.read_exact(&mut buf).unwrap();
assert_eq!(buf, [20]);
second_partition.read_exact(&mut buf).unwrap();
assert_eq!(buf, [45]);

second_partition.seek(SeekFrom::Start(5)).unwrap();
let mut second_clone = second_partition.clone();
let handle = thread::spawn(move || {
    second_clone.seek(SeekFrom::Current(2)).unwrap();
    let mut buf = [0];
    second_clone.read_exact(&mut buf).unwrap();
    buf[0]
});

second_partition.seek(SeekFrom::End(-1)).unwrap();
second_partition.read_exact(&mut buf).unwrap();

assert_eq!(handle.join().unwrap(), 47);
assert_eq!(buf[0], 69);

first_partition.seek(SeekFrom::Start(2)).unwrap();
{
    let mut locked = first_partition.lock().unwrap();
    let mut buffer = [0; 2];
    locked.read_exact(&mut buffer);
    assert_eq!(&buffer, &[12, 13]);
}

Implementations

impl<T: Read + Seek> PartitionMutex<T>

pub fn new(
    file: Arc<Mutex<T>>,
    start: u64,
    lenght: u64
) -> Result<PartitionMutex<T>>

Create new PartitionMutex, with the specified input file, start and lenght

pub fn lock(&mut self) -> Result<PartitionMutexLock<'_, T>, LockPartitionError>

Lock this PartitionMutex, in a similar fashion to Mutex::lock. If the same thread lock this PartitionMutex, or any other structure that use the same file, without first checking it is free, it might panic or softlock. Note that the seek/read implementation of PartitionMutex will lock the file for the duration of those function execution. you can use scope for this.

Trait Implementations

impl<T: Clone + Read + Seek> Clone for PartitionMutex<T>

fn clone(&self) -> PartitionMutex<T>

Returns a copy of the value.

pub fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug + Read + Seek> Debug for PartitionMutex<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: Read + Seek> Read for PartitionMutex<T>

fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

pub fn read_vectored(
    &mut self,
    bufs: &mut [IoSliceMut<'_>]
) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

pub fn is_read_vectored(&self) -> bool

🔬 This is a nightly-only experimental API. (can_vector)

Determines if this Reader has an efficient read_vectored implementation.

pub unsafe fn initializer(&self) -> Initializer

🔬 This is a nightly-only experimental API. (read_initializer)

Determines if this Reader can work with buffers of uninitialized memory.

pub fn read_to_end(&mut self, buf: &mut Vec<u8, Global>) -> Result<usize, Error>

Read all bytes until EOF in this source, placing them into buf.

pub fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until EOF in this source, appending them to buf.

pub fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Read the exact number of bytes required to fill buf.

pub fn by_ref(&mut self) -> &mut Self

Creates a "by reference" adaptor for this instance of Read.

pub fn bytes(self) -> Bytes<Self>

Transforms this Read instance to an Iterator over its bytes.

pub fn chain<R>(self, next: R) -> Chain<Self, R> where
    R: Read, 

Creates an adaptor which will chain this stream with another.

pub fn take(self, limit: u64) -> Take<Self>

Creates an adaptor which will read at most limit bytes from it.

impl<T: Read + Seek> Seek for PartitionMutex<T>

fn seek(&mut self, target: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in a stream.

pub fn stream_len(&mut self) -> Result<u64, Error>

🔬 This is a nightly-only experimental API. (seek_stream_len)

Returns the length of this stream (in bytes).

pub fn stream_position(&mut self) -> Result<u64, Error>

Returns the current seek position from the start of the stream.

impl<T: Read + Seek> Write for PartitionMutex<T>

fn write(&mut self, _: &[u8]) -> Result<usize>

Do not use this write function. It will always fail. It is just here because some library require this to have the Write trait to make this work with this (rust_vfs)

fn flush(&mut self) -> Result<()>

Always suceed. It is useless to call it

pub fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

pub fn is_write_vectored(&self) -> bool

🔬 This is a nightly-only experimental API. (can_vector)

Determines if this Writer has an efficient write_vectored implementation.

pub fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

pub fn write_all_vectored(
    &mut self,
    bufs: &mut [IoSlice<'_>]
) -> Result<(), Error>

🔬 This is a nightly-only experimental API. (write_all_vectored)

Attempts to write multiple buffers into this writer.

pub fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

pub fn by_ref(&mut self) -> &mut Self

Creates a "by reference" adaptor for this instance of Write.