Rollup merge of #136876 - joshtriplett:locking-might-not-be-advisory, r=Amanieu
Locking documentation updates - Reword file lock documentation to clarify advisory vs mandatory. Remove the word "advisory", and make it more explicit that the lock may be advisory or mandatory depending on platform. - Document that locking a file fails on Windows if the file is opened only for append
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Matthias Krüger
GitHub
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5a942d67a6
1 changed files with 58 additions and 38 deletions
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@ -624,21 +624,21 @@ impl File {
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self.inner.datasync()
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}
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/// Acquire an exclusive advisory lock on the file. Blocks until the lock can be acquired.
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/// Acquire an exclusive lock on the file. Blocks until the lock can be acquired.
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///
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/// This acquires an exclusive advisory lock; no other file handle to this file may acquire
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/// another lock.
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/// This acquires an exclusive lock; no other file handle to this file may acquire another lock.
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///
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/// If this file handle/descriptor, or a clone of it, already holds an advisory lock the exact
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/// behavior is unspecified and platform dependent, including the possibility that it will
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/// deadlock. However, if this method returns, then an exclusive lock is held.
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/// This lock may be advisory or mandatory. This lock is meant to interact with [`lock`],
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/// [`try_lock`], [`lock_shared`], [`try_lock_shared`], and [`unlock`]. Its interactions with
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/// other methods, such as [`read`] and [`write`] are platform specific, and it may or may not
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/// cause non-lockholders to block.
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///
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/// If this file handle/descriptor, or a clone of it, already holds an lock the exact behavior
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/// is unspecified and platform dependent, including the possibility that it will deadlock.
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/// However, if this method returns, then an exclusive lock is held.
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///
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/// If the file not open for writing, it is unspecified whether this function returns an error.
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///
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/// Note, this is an advisory lock meant to interact with [`lock_shared`], [`try_lock`],
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/// [`try_lock_shared`], and [`unlock`]. Its interactions with other methods, such as [`read`]
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/// and [`write`] are platform specific, and it may or may not cause non-lockholders to block.
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///
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/// The lock will be released when this file (along with any other file descriptors/handles
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/// duplicated or inherited from it) is closed, or if the [`unlock`] method is called.
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///
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@ -648,8 +648,12 @@ impl File {
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/// and the `LockFileEx` function on Windows with the `LOCKFILE_EXCLUSIVE_LOCK` flag. Note that,
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/// this [may change in the future][changes].
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///
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/// On Windows, locking a file will fail if the file is opened only for append. To lock a file,
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/// open it with one of `.read(true)`, `.read(true).append(true)`, or `.write(true)`.
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///
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/// [changes]: io#platform-specific-behavior
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///
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/// [`lock`]: File::lock
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/// [`lock_shared`]: File::lock_shared
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/// [`try_lock`]: File::try_lock
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/// [`try_lock_shared`]: File::try_lock_shared
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@ -674,18 +678,19 @@ impl File {
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self.inner.lock()
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}
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/// Acquire a shared (non-exclusive) advisory lock on the file. Blocks until the lock can be acquired.
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/// Acquire a shared (non-exclusive) lock on the file. Blocks until the lock can be acquired.
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///
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/// This acquires a shared advisory lock; more than one file handle may hold a shared lock, but
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/// none may hold an exclusive lock at the same time.
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/// This acquires a shared lock; more than one file handle may hold a shared lock, but none may
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/// hold an exclusive lock at the same time.
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///
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/// If this file handle/descriptor, or a clone of it, already holds an advisory lock, the exact
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/// behavior is unspecified and platform dependent, including the possibility that it will
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/// deadlock. However, if this method returns, then a shared lock is held.
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/// This lock may be advisory or mandatory. This lock is meant to interact with [`lock`],
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/// [`try_lock`], [`lock_shared`], [`try_lock_shared`], and [`unlock`]. Its interactions with
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/// other methods, such as [`read`] and [`write`] are platform specific, and it may or may not
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/// cause non-lockholders to block.
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///
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/// Note, this is an advisory lock meant to interact with [`lock`], [`try_lock`],
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/// [`try_lock_shared`], and [`unlock`]. Its interactions with other methods, such as [`read`]
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/// and [`write`] are platform specific, and it may or may not cause non-lockholders to block.
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/// If this file handle/descriptor, or a clone of it, already holds an lock, the exact behavior
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/// is unspecified and platform dependent, including the possibility that it will deadlock.
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/// However, if this method returns, then a shared lock is held.
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///
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/// The lock will be released when this file (along with any other file descriptors/handles
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/// duplicated or inherited from it) is closed, or if the [`unlock`] method is called.
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@ -696,9 +701,13 @@ impl File {
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/// and the `LockFileEx` function on Windows. Note that, this
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/// [may change in the future][changes].
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///
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/// On Windows, locking a file will fail if the file is opened only for append. To lock a file,
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/// open it with one of `.read(true)`, `.read(true).append(true)`, or `.write(true)`.
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///
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/// [changes]: io#platform-specific-behavior
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///
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/// [`lock`]: File::lock
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/// [`lock_shared`]: File::lock_shared
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/// [`try_lock`]: File::try_lock
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/// [`try_lock_shared`]: File::try_lock_shared
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/// [`unlock`]: File::unlock
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@ -722,25 +731,24 @@ impl File {
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self.inner.lock_shared()
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}
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/// Try to acquire an exclusive advisory lock on the file.
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/// Try to acquire an exclusive lock on the file.
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///
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/// Returns `Ok(false)` if a different lock is already held on this file (via another
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/// handle/descriptor).
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///
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/// This acquires an exclusive advisory lock; no other file handle to this file may acquire
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/// another lock.
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/// This acquires an exclusive lock; no other file handle to this file may acquire another lock.
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///
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/// If this file handle/descriptor, or a clone of it, already holds an advisory lock, the exact
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/// behavior is unspecified and platform dependent, including the possibility that it will
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/// deadlock. However, if this method returns `Ok(true)`, then it has acquired an exclusive
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/// lock.
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/// This lock may be advisory or mandatory. This lock is meant to interact with [`lock`],
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/// [`try_lock`], [`lock_shared`], [`try_lock_shared`], and [`unlock`]. Its interactions with
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/// other methods, such as [`read`] and [`write`] are platform specific, and it may or may not
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/// cause non-lockholders to block.
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///
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/// If this file handle/descriptor, or a clone of it, already holds an lock, the exact behavior
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/// is unspecified and platform dependent, including the possibility that it will deadlock.
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/// However, if this method returns `Ok(true)`, then it has acquired an exclusive lock.
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///
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/// If the file not open for writing, it is unspecified whether this function returns an error.
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///
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/// Note, this is an advisory lock meant to interact with [`lock`], [`lock_shared`],
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/// [`try_lock_shared`], and [`unlock`]. Its interactions with other methods, such as [`read`]
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/// and [`write`] are platform specific, and it may or may not cause non-lockholders to block.
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///
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/// The lock will be released when this file (along with any other file descriptors/handles
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/// duplicated or inherited from it) is closed, or if the [`unlock`] method is called.
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///
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@ -751,10 +759,14 @@ impl File {
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/// and `LOCKFILE_FAIL_IMMEDIATELY` flags. Note that, this
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/// [may change in the future][changes].
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///
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/// On Windows, locking a file will fail if the file is opened only for append. To lock a file,
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/// open it with one of `.read(true)`, `.read(true).append(true)`, or `.write(true)`.
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///
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/// [changes]: io#platform-specific-behavior
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///
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/// [`lock`]: File::lock
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/// [`lock_shared`]: File::lock_shared
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/// [`try_lock`]: File::try_lock
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/// [`try_lock_shared`]: File::try_lock_shared
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/// [`unlock`]: File::unlock
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/// [`read`]: Read::read
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@ -777,22 +789,23 @@ impl File {
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self.inner.try_lock()
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}
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/// Try to acquire a shared (non-exclusive) advisory lock on the file.
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/// Try to acquire a shared (non-exclusive) lock on the file.
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///
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/// Returns `Ok(false)` if an exclusive lock is already held on this file (via another
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/// handle/descriptor).
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///
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/// This acquires a shared advisory lock; more than one file handle may hold a shared lock, but
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/// none may hold an exclusive lock at the same time.
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/// This acquires a shared lock; more than one file handle may hold a shared lock, but none may
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/// hold an exclusive lock at the same time.
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///
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/// If this file handle, or a clone of it, already holds an advisory lock, the exact behavior is
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/// This lock may be advisory or mandatory. This lock is meant to interact with [`lock`],
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/// [`try_lock`], [`lock_shared`], [`try_lock_shared`], and [`unlock`]. Its interactions with
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/// other methods, such as [`read`] and [`write`] are platform specific, and it may or may not
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/// cause non-lockholders to block.
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///
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/// If this file handle, or a clone of it, already holds an lock, the exact behavior is
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/// unspecified and platform dependent, including the possibility that it will deadlock.
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/// However, if this method returns `Ok(true)`, then it has acquired a shared lock.
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///
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/// Note, this is an advisory lock meant to interact with [`lock`], [`try_lock`],
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/// [`try_lock`], and [`unlock`]. Its interactions with other methods, such as [`read`]
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/// and [`write`] are platform specific, and it may or may not cause non-lockholders to block.
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///
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/// The lock will be released when this file (along with any other file descriptors/handles
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/// duplicated or inherited from it) is closed, or if the [`unlock`] method is called.
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///
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@ -803,11 +816,15 @@ impl File {
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/// `LOCKFILE_FAIL_IMMEDIATELY` flag. Note that, this
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/// [may change in the future][changes].
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///
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/// On Windows, locking a file will fail if the file is opened only for append. To lock a file,
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/// open it with one of `.read(true)`, `.read(true).append(true)`, or `.write(true)`.
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///
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/// [changes]: io#platform-specific-behavior
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///
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/// [`lock`]: File::lock
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/// [`lock_shared`]: File::lock_shared
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/// [`try_lock`]: File::try_lock
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/// [`try_lock_shared`]: File::try_lock_shared
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/// [`unlock`]: File::unlock
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/// [`read`]: Read::read
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/// [`write`]: Write::write
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@ -844,6 +861,9 @@ impl File {
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/// and the `UnlockFile` function on Windows. Note that, this
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/// [may change in the future][changes].
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///
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/// On Windows, locking a file will fail if the file is opened only for append. To lock a file,
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/// open it with one of `.read(true)`, `.read(true).append(true)`, or `.write(true)`.
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///
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/// [changes]: io#platform-specific-behavior
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///
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/// # Examples
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