From ac470e95852336172197810a9a4f6d2e8c8b6574 Mon Sep 17 00:00:00 2001 From: Benoît du Garreau Date: Thu, 29 Apr 2021 09:53:19 +0200 Subject: Multiple improvements to RwLocks - Split `sys_common::RWLock` between `StaticRWLock` and `MovableRWLock` - Unbox `RwLock` on some platforms (Windows, Wasm and unsupported) - Simplify `RwLock::into_inner` --- library/std/src/sys/hermit/rwlock.rs | 2 ++ library/std/src/sys/sgx/rwlock.rs | 2 ++ library/std/src/sys/unix/os.rs | 11 +++--- library/std/src/sys/unix/rwlock.rs | 54 ++---------------------------- library/std/src/sys/unsupported/rwlock.rs | 2 ++ library/std/src/sys/wasm/atomics/rwlock.rs | 2 ++ library/std/src/sys/windows/rwlock.rs | 2 ++ 7 files changed, 17 insertions(+), 58 deletions(-) (limited to 'library/std/src/sys') diff --git a/library/std/src/sys/hermit/rwlock.rs b/library/std/src/sys/hermit/rwlock.rs index 06442e925f4..d2058180121 100644 --- a/library/std/src/sys/hermit/rwlock.rs +++ b/library/std/src/sys/hermit/rwlock.rs @@ -8,6 +8,8 @@ pub struct RWLock { state: UnsafeCell, } +pub type MovableRWLock = Box; + enum State { Unlocked, Reading(usize), diff --git a/library/std/src/sys/sgx/rwlock.rs b/library/std/src/sys/sgx/rwlock.rs index 0c96e3fcddc..2d038b51896 100644 --- a/library/std/src/sys/sgx/rwlock.rs +++ b/library/std/src/sys/sgx/rwlock.rs @@ -13,6 +13,8 @@ pub struct RWLock { writer: SpinMutex>, } +pub type MovableRWLock = Box; + // Check at compile time that RWLock size matches C definition (see test_c_rwlock_initializer below) // // # Safety diff --git a/library/std/src/sys/unix/os.rs b/library/std/src/sys/unix/os.rs index bbc4691d963..41ca9762390 100644 --- a/library/std/src/sys/unix/os.rs +++ b/library/std/src/sys/unix/os.rs @@ -20,8 +20,7 @@ use crate::str; use crate::sys::cvt; use crate::sys::fd; use crate::sys::memchr; -use crate::sys::rwlock::{RWLockReadGuard, StaticRWLock}; -use crate::sys_common::mutex::{StaticMutex, StaticMutexGuard}; +use crate::sys_common::rwlock::{StaticRWLock, StaticRWLockReadGuard}; use crate::vec; use libc::{c_char, c_int, c_void}; @@ -490,8 +489,8 @@ pub unsafe fn environ() -> *mut *const *const c_char { static ENV_LOCK: StaticRWLock = StaticRWLock::new(); -pub fn env_read_lock() -> RWLockReadGuard { - ENV_LOCK.read_with_guard() +pub fn env_read_lock() -> StaticRWLockReadGuard { + ENV_LOCK.read() } /// Returns a vector of (variable, value) byte-vector pairs for all the @@ -551,7 +550,7 @@ pub fn setenv(k: &OsStr, v: &OsStr) -> io::Result<()> { let v = CString::new(v.as_bytes())?; unsafe { - let _guard = ENV_LOCK.write_with_guard(); + let _guard = ENV_LOCK.write(); cvt(libc::setenv(k.as_ptr(), v.as_ptr(), 1)).map(drop) } } @@ -560,7 +559,7 @@ pub fn unsetenv(n: &OsStr) -> io::Result<()> { let nbuf = CString::new(n.as_bytes())?; unsafe { - let _guard = ENV_LOCK.write_with_guard(); + let _guard = ENV_LOCK.write(); cvt(libc::unsetenv(nbuf.as_ptr())).map(drop) } } diff --git a/library/std/src/sys/unix/rwlock.rs b/library/std/src/sys/unix/rwlock.rs index d97d9d712fc..b1faf12c226 100644 --- a/library/std/src/sys/unix/rwlock.rs +++ b/library/std/src/sys/unix/rwlock.rs @@ -7,6 +7,8 @@ pub struct RWLock { num_readers: AtomicUsize, } +pub type MovableRWLock = Box; + unsafe impl Send for RWLock {} unsafe impl Sync for RWLock {} @@ -139,55 +141,3 @@ impl RWLock { } } } - -pub struct StaticRWLock(RWLock); - -impl StaticRWLock { - pub const fn new() -> StaticRWLock { - StaticRWLock(RWLock::new()) - } - - /// Acquires shared access to the underlying lock, blocking the current - /// thread to do so. - /// - /// The lock is automatically unlocked when the returned guard is dropped. - #[inline] - pub fn read_with_guard(&'static self) -> RWLockReadGuard { - // SAFETY: All methods require static references, therefore self - // cannot be moved between invocations. - unsafe { - self.0.read(); - } - RWLockReadGuard(&self.0) - } - - /// Acquires write access to the underlying lock, blocking the current thread - /// to do so. - /// - /// The lock is automatically unlocked when the returned guard is dropped. - #[inline] - pub fn write_with_guard(&'static self) -> RWLockWriteGuard { - // SAFETY: All methods require static references, therefore self - // cannot be moved between invocations. - unsafe { - self.0.write(); - } - RWLockWriteGuard(&self.0) - } -} - -pub struct RWLockReadGuard(&'static RWLock); - -impl Drop for RWLockReadGuard { - fn drop(&mut self) { - unsafe { self.0.read_unlock() } - } -} - -pub struct RWLockWriteGuard(&'static RWLock); - -impl Drop for RWLockWriteGuard { - fn drop(&mut self) { - unsafe { self.0.write_unlock() } - } -} diff --git a/library/std/src/sys/unsupported/rwlock.rs b/library/std/src/sys/unsupported/rwlock.rs index 6982b2b155f..8438adeb5b5 100644 --- a/library/std/src/sys/unsupported/rwlock.rs +++ b/library/std/src/sys/unsupported/rwlock.rs @@ -5,6 +5,8 @@ pub struct RWLock { mode: Cell, } +pub type MovableRWLock = RWLock; + unsafe impl Send for RWLock {} unsafe impl Sync for RWLock {} // no threads on this platform diff --git a/library/std/src/sys/wasm/atomics/rwlock.rs b/library/std/src/sys/wasm/atomics/rwlock.rs index 06442e925f4..64eaa2fc482 100644 --- a/library/std/src/sys/wasm/atomics/rwlock.rs +++ b/library/std/src/sys/wasm/atomics/rwlock.rs @@ -8,6 +8,8 @@ pub struct RWLock { state: UnsafeCell, } +pub type MovableRWLock = RWLock; + enum State { Unlocked, Reading(usize), diff --git a/library/std/src/sys/windows/rwlock.rs b/library/std/src/sys/windows/rwlock.rs index a769326352c..b7a5b1e7acc 100644 --- a/library/std/src/sys/windows/rwlock.rs +++ b/library/std/src/sys/windows/rwlock.rs @@ -5,6 +5,8 @@ pub struct RWLock { inner: UnsafeCell, } +pub type MovableRWLock = RWLock; + unsafe impl Send for RWLock {} unsafe impl Sync for RWLock {} -- cgit 1.4.1-3-g733a5