Enum FileLocking 

pub enum FileLocking {
    Enabled,
    Disabled,
    BestEffort,
}

File-locking policy applied at file open time.

Platform notes

On Unix (flock(2) / fcntl(F_OFD_SETLK)) the lock is advisory: a handle without a lock can still read and write a file that another handle has locked. Setting FileLocking::Disabled or FileLocking::BestEffort therefore lets the opener bypass another process’s lock at the cost of safety.

On Windows (LockFileEx) the lock is mandatory: while one handle holds an exclusive range lock, no other handle (regardless of locking policy) can read or write that range — WriteFile and ReadFile return ERROR_LOCK_VIOLATION (33). Disabled and BestEffort only control whether we try to acquire a lock, not whether the OS enforces locks held by other handles. The HDF5 C library has the same limitation on Windows.

Variants

Enabled

Acquire the lock; fail to open if it cannot be acquired (the HDF5 C-library default).

Disabled

Skip locking entirely. On Windows, OS-level locks held by other handles still apply.

BestEffort

Try to acquire the lock; if the filesystem doesn’t support locking (e.g. NFS), proceed without one. On Unix this also proceeds when the lock is contended; on Windows the resulting reads/writes still fail at the OS level if another handle holds a conflicting LockFileEx lock.

Implementations

impl FileLocking

pub fn from_env() -> Self

Returns the policy implied by the HDF5_USE_FILE_LOCKING environment variable, falling back to FileLocking::Enabled.

pub fn from_env_or(default: FileLocking) -> Self

Returns the policy implied by the env var if set, otherwise default.

Trait Implementations

impl Clone for FileLocking

fn clone(&self) -> FileLocking

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FileLocking

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

Formats the value using the given formatter.

impl Default for FileLocking

fn default() -> FileLocking

Returns the “default value” for a type.

impl PartialEq for FileLocking

fn eq(&self, other: &FileLocking) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for FileLocking

impl Eq for FileLocking

impl StructuralPartialEq for FileLocking