Struct File

pub struct File { /* private fields */ }

Locks a resource to eventually be overwritten with the content of this file.

Dropping the file without committing will delete it, leaving the underlying resource unchanged.

Implementations

impl File

pub fn acquire_to_update_resource( at_path: impl AsRef<Path>, mode: Fail, boundary_directory: Option<PathBuf>, ) -> Result<File, Error>

Create a writable lock file with failure mode whose content will eventually overwrite the given resource at_path.

If boundary_directory is given, non-existing directories will be created automatically and removed in the case of a rollback. Otherwise the containing directory is expected to exist, even though the resource doesn’t have to.

Note that permissions will be set to 0o666, which usually results in 0o644 after passing a default umask, on Unix systems.

Warning of potential resource leak

Please note that the underlying file will remain if destructors don’t run, as is the case when interrupting the application. This results in the resource being locked permanently unless the lock file is removed by other means. See the crate documentation for more information.

pub fn acquire_to_update_resource_with_permissions( at_path: impl AsRef<Path>, mode: Fail, boundary_directory: Option<PathBuf>, make_permissions: impl Fn() -> Permissions, ) -> Result<File, Error>

Like acquire_to_update_resource(), but allows to set filesystem permissions using make_permissions.

impl File

pub fn commit(self) -> Result<(PathBuf, Option<File>), Error<Self>>

Commit the changes written to this lock file and overwrite the original file atomically, returning the resource path and an open file handle on success.

impl File

pub fn with_mut<T>( &mut self, f: impl FnOnce(&mut File) -> Result<T>, ) -> Result<T>

Obtain a mutable reference to the write handle and call f(out) with it.

pub fn close(self) -> Result<Marker>

Close the lock file to prevent further writes and to save system resources. A call to Marker::commit() is allowed on the Marker to write changes back to the resource.

pub fn lock_path(&self) -> &Path

Return the path at which the lock file resides

pub fn resource_path(&self) -> PathBuf

Return the path at which the locked resource resides

Trait Implementations

impl Debug for File

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

Formats the value using the given formatter.

impl Read for File

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.

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

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

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.

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

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

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

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

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

Reads the exact number of bytes required to fill buf.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error>

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

Pull some bytes from this source into the specified buffer.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

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

Reads the exact number of bytes required to fill cursor.

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

where Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

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

where R: Read, Self: Sized,

Creates an adapter which will chain this stream with another.

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

where Self: Sized,

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

impl Seek for File

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

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

fn rewind(&mut self) -> Result<(), Error>

Rewind to the beginning of a stream.

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).

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

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

fn seek_relative(&mut self, offset: i64) -> Result<(), Error>

Seeks relative to the current position.

impl Write for File

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

Writes a buffer into this writer, returning how many bytes were written.

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

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

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

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

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.

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

Attempts to write an entire buffer into this writer.

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.

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

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

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

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.