parking_lot

Release parking_lot 0.12.2, parking_lot_core 0.9.10, lock_api 0.4.12

• Fixed incorrect memory ordering in RwLock. (#344)
• Added Condvar::wait_while convenience methods (#343)

• The MSRV is bumped to 1.49.0.
• Disabled eventual fairness on wasm32-unknown-unknown. (#302)
• Added a rwlock method to report if lock is held exclusively. (#303)
• Use new asm! macro. (#304)
• Use windows-rs instead of winapi for faster builds. (#311)
• Moved hardware lock elision support to a separate Cargo feature. (#313)
• Removed used of deprecated spin_loop_hint. (#314)

• Fixed incorrect memory orderings on RwLock and WordLock. (#294, #292)
• Added Arc-based lock guards. (#291)
• Added workaround for TSan's lack of support for fence. (#292)

• Fix bounds on Send and Sync impls for lock guards. (#262)
• Fix incorrect memory ordering in RwLock. (#260)

• Add is_locked method to mutex types. (#235)
• Make RawReentrantMutex public. (#233)
• Allow lock guard to be sent to another thread with the send_guard feature. (#240)
• Use Instant type from the instant crate on wasm32-unknown-unknown. (#231)
• Remove deprecated and unsound MappedRwLockWriteGuard::downgrade. (#244)
• Most methods on the Raw* traits have been made unsafe since they assume the current thread holds the lock. (#243)

• Update minimum version of lock_api.

• Add methods to construct Mutex, RwLock, etc in a const context. (#217)
• Add FairMutex which always uses fair unlocking. (#204)
• Fixed panic with deadlock detection on macOS. (#203)
• Fixed incorrect synchronization in create_hashtable. (#210)
• Use llvm_asm! instead of the deprecated asm!. (#223)

• Upgrade smallvec dependency to 1.0 in parking_lot_core.
• Replace all usage of mem::uninitialized with mem::MaybeUninit.
• The minimum required Rust version is bumped to 1.36. Because of the above two changes.
• Make methods on WaitTimeoutResult and OnceState take self by value instead of reference.

• Re-export lock_api (0.3.1) from parking_lot (#150)
• Removed (non-dev) dependency on rand crate for fairness mechanism, by including a simple xorshift PRNG in core (#144)
• Android now uses the futex-based ThreadParker. (#140)
• Fixed CloudABI ThreadParker. (#140)
• Fix race condition in lock_api::ReentrantMutex (da16c2c7)

• Removed deprecated CloudABI support. (#263)
• Fixed build on wasm32-unknown-unknown. (#265)
• Relaxed dependency on smallvec. (#266)

• Fix race conditions in deadlock detection.
• Support for more platforms by adding ThreadParker implementations for Wasm, Redox, SGX and CloudABI.
• Drop support for older Rust. parking_lot now requires 1.31 and is a Rust 2018 edition crate (#122).
• Disable the owning_ref feature by default.
• Fix was_last_thread value in the timeout callback of park() (#129).
• Support single byte Mutex/Once on stable Rust when compiler is at least version 1.34.
• Make Condvar::new and Once::new const fns on stable Rust and remove ONCE_INIT (#134).
• Add optional Serde support (#135).

• Fixed potential deadlock when upgrading a RwLock.
• Fixed overflow panic on very long timeouts (#111).

• Return if or how many threads were notified from Condvar::notify_*

• Export RawMutex, RawRwLock and RawThreadId.

• Fixed compile error on Windows with old cfg_if version. (#164)

• Fixed Android build. (#163)

This release moves most of the code for type-safe Mutex and RwLock types into a separate crate called lock_api. This new crate is compatible with no_std and provides Mutex and RwLock type-safe wrapper types from a raw mutex type which implements the RawMutex or RawRwLock trait. The API provided by the wrapper types can be extended by implementing more traits on the raw mutex type which provide more functionality (e.g. RawMutexTimed). See the crate documentation for more details.

There are also several major changes:

• The minimum required Rust version is bumped to 1.26.
• All methods on MutexGuard (and other guard types) are no longer inherent methods and must be called as MutexGuard::method(self). This avoids conflicts with methods from the inner type.
• MutexGuard (and other guard types) add the unlocked method which temporarily unlocks a mutex, runs the given closure, and then re-locks the mutex.
• MutexGuard (and other guard types) add the bump method which gives a chance for other threads to acquire the mutex by temporarily unlocking it and re-locking it. However this is optimized for the common case where there are no threads waiting on the lock, in which case no unlocking is performed.
• MutexGuard (and other guard types) add the map method which returns a MappedMutexGuard which holds only a subset of the original locked type. The MappedMutexGuard type is identical to MutexGuard except that it does not support the unlocked and bump methods, and can't be used with CondVar.

• Fixed unsound Sync/Send impls for ArcMutexGuard. (#349)
• Added ArcMutexGuard::into_arc. (#350)

• Update for latest nightly. (#281)

• Added [Raw]ReentrantMutex::is_owned. (#280)

• Deprecate unsound MappedRwLockWriteGuard::downgrade (#198)

• Use NonZeroUsize in GetThreadId::nonzero_thread_id (#148)
• Debug assert lock_count in ReentrantMutex (#148)
• Tag as unsafe and document some internal methods (#148)
• This release was yanked due to a regression in ReentrantMutex (da16c2c7)