[−][src]Struct advisory_lock::AdvisoryFileLock
An advisory lock for files.
An advisory lock provides a mutual-exclusion mechanism among processes which explicitly acquires and releases the lock. Processes that are not aware of the lock will ignore it.
AdvisoryFileLock
provides following features:
- Blocking or non-blocking operations.
- Shared or exclusive modes.
- All operations are thread-safe.
Notes
AdvisoryFileLock
has following limitations:
- Locks are allowed only on files, but not directories.
Implementations
impl AdvisoryFileLock
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pub fn new<P: AsRef<Path>>(
path: P,
file_lock_mode: FileLockMode
) -> Result<Self, FileLockError>
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path: P,
file_lock_mode: FileLockMode
) -> Result<Self, FileLockError>
Create a new FileLock
.
pub fn is_shared(&self) -> bool
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Return true
if the advisory lock is acquired by shared mode.
pub fn is_exclusive(&self) -> bool
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Return true
if the advisory lock is acquired by exclusive mode.
pub fn lock(&mut self) -> Result<(), FileLockError>
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Acquire the advisory file lock.
lock
is blocking; it will block the current thread until it succeeds or errors.
pub fn try_lock(&mut self) -> Result<(), FileLockError>
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Try to acquire the advisory file lock.
try_lock
returns immediately.
pub fn unlock(&mut self) -> Result<(), FileLockError>
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Unlock this advisory file lock.
Methods from Deref<Target = File>
pub fn sync_all(&self) -> Result<(), Error>
1.0.0[src]
Attempts to sync all OS-internal metadata to disk.
This function will attempt to ensure that all in-memory data reaches the filesystem before returning.
This can be used to handle errors that would otherwise only be caught
when the File
is closed. Dropping a file will ignore errors in
synchronizing this in-memory data.
Examples
use std::fs::File; use std::io::prelude::*; fn main() -> std::io::Result<()> { let mut f = File::create("foo.txt")?; f.write_all(b"Hello, world!")?; f.sync_all()?; Ok(()) }
pub fn sync_data(&self) -> Result<(), Error>
1.0.0[src]
This function is similar to sync_all
, except that it may not
synchronize file metadata to the filesystem.
This is intended for use cases that must synchronize content, but don't need the metadata on disk. The goal of this method is to reduce disk operations.
Note that some platforms may simply implement this in terms of
sync_all
.
Examples
use std::fs::File; use std::io::prelude::*; fn main() -> std::io::Result<()> { let mut f = File::create("foo.txt")?; f.write_all(b"Hello, world!")?; f.sync_data()?; Ok(()) }
pub fn set_len(&self, size: u64) -> Result<(), Error>
1.0.0[src]
Truncates or extends the underlying file, updating the size of
this file to become size
.
If the size
is less than the current file's size, then the file will
be shrunk. If it is greater than the current file's size, then the file
will be extended to size
and have all of the intermediate data filled
in with 0s.
The file's cursor isn't changed. In particular, if the cursor was at the end and the file is shrunk using this operation, the cursor will now be past the end.
Errors
This function will return an error if the file is not opened for writing. Also, std::io::ErrorKind::InvalidInput will be returned if the desired length would cause an overflow due to the implementation specifics.
Examples
use std::fs::File; fn main() -> std::io::Result<()> { let mut f = File::create("foo.txt")?; f.set_len(10)?; Ok(()) }
Note that this method alters the content of the underlying file, even
though it takes &self
rather than &mut self
.
pub fn metadata(&self) -> Result<Metadata, Error>
1.0.0[src]
Queries metadata about the underlying file.
Examples
use std::fs::File; fn main() -> std::io::Result<()> { let mut f = File::open("foo.txt")?; let metadata = f.metadata()?; Ok(()) }
pub fn try_clone(&self) -> Result<File, Error>
1.9.0[src]
Creates a new File
instance that shares the same underlying file handle
as the existing File
instance. Reads, writes, and seeks will affect
both File
instances simultaneously.
Examples
Creates two handles for a file named foo.txt
:
use std::fs::File; fn main() -> std::io::Result<()> { let mut file = File::open("foo.txt")?; let file_copy = file.try_clone()?; Ok(()) }
Assuming there’s a file named foo.txt
with contents abcdef\n
, create
two handles, seek one of them, and read the remaining bytes from the
other handle:
use std::fs::File; use std::io::SeekFrom; use std::io::prelude::*; fn main() -> std::io::Result<()> { let mut file = File::open("foo.txt")?; let mut file_copy = file.try_clone()?; file.seek(SeekFrom::Start(3))?; let mut contents = vec![]; file_copy.read_to_end(&mut contents)?; assert_eq!(contents, b"def\n"); Ok(()) }
pub fn set_permissions(&self, perm: Permissions) -> Result<(), Error>
1.16.0[src]
Changes the permissions on the underlying file.
Platform-specific behavior
This function currently corresponds to the fchmod
function on Unix and
the SetFileInformationByHandle
function on Windows. Note that, this
may change in the future.
Errors
This function will return an error if the user lacks permission change attributes on the underlying file. It may also return an error in other os-specific unspecified cases.
Examples
fn main() -> std::io::Result<()> { use std::fs::File; let file = File::open("foo.txt")?; let mut perms = file.metadata()?.permissions(); perms.set_readonly(true); file.set_permissions(perms)?; Ok(()) }
Note that this method alters the permissions of the underlying file,
even though it takes &self
rather than &mut self
.
Trait Implementations
impl Deref for AdvisoryFileLock
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impl DerefMut for AdvisoryFileLock
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impl Drop for AdvisoryFileLock
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Auto Trait Implementations
impl RefUnwindSafe for AdvisoryFileLock
impl Send for AdvisoryFileLock
impl Sync for AdvisoryFileLock
impl Unpin for AdvisoryFileLock
impl UnwindSafe for AdvisoryFileLock
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,