Skip to content

Use os_unfair_lock on Darwin platforms #882

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 1 commit into from
Closed

Use os_unfair_lock on Darwin platforms #882

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
28 changes: 13 additions & 15 deletions Sources/SwiftSyntax/PlatformMutex.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -20,8 +20,9 @@

/// A protocol that platform-specific mutual exclusion primitives should conform to.
final class PlatformMutex {
// FIXME: Use os_unfair_lock when we bump to macOS 12.0 on Darwin
#if canImport(Darwin) || canImport(Glibc)
#if canImport(Darwin)
typealias Primitive = os_unfair_lock
#elseif canImport(Glibc)
typealias Primitive = pthread_mutex_t
#elseif canImport(WinSDK)
typealias Primitive = SRWLOCK
Expand All @@ -45,7 +46,9 @@ final class PlatformMutex {
/// - Warning: Do not call `.deallocate()` on any pointers allocated by the
/// `BumpPtrAllocator` here.
func deinitialize() {
#if canImport(Darwin) || canImport(Glibc)
#if canImport(Darwin)
self.lock.deinitialize(count: 1)
#elseif canImport(Glibc)
pthread_mutex_destroy(self.lock)
#endif
self.lock.deinitialize(count: 1)
Expand All @@ -62,16 +65,7 @@ final class PlatformMutex {
extension PlatformMutex {
private static func initialize(_ platformLock: PlatformLock) {
#if canImport(Darwin)
// HACK: On Darwin, the value of PTHREAD_MUTEX_INITIALIZER installs
// signature bits into the mutex that are later checked by other aspects
// of the mutex API. This is a completely optional POSIX-ism that most
// Linuxes don't implement - often so that (global) lock variables can be
// stuck in .bss. Swift doesn't know how to import
// PTHREAD_MUTEX_INITIALIZER, so we'll replicate its signature-installing
// magic with the bit it can import.
platformLock.pointee.__sig = Int(_PTHREAD_MUTEX_SIG_init)
let result = pthread_mutex_init(platformLock, nil)
precondition(result == 0)
// Platform specific initialization is not needed.
#elseif canImport(Glibc)
let result = pthread_mutex_init(platformLock, nil)
precondition(result == 0)
Expand All @@ -81,7 +75,9 @@ extension PlatformMutex {
}

private static func lock(_ platformLock: PlatformLock) {
#if canImport(Darwin) || canImport(Glibc)
#if canImport(Darwin)
os_unfair_lock_lock(platformLock)
#elseif canImport(Glibc)
let result = pthread_mutex_lock(platformLock)
assert(result == 0)
#elseif canImport(WinSDK)
Expand All @@ -90,7 +86,9 @@ extension PlatformMutex {
}

private static func unlock(_ platformLock: PlatformLock) {
#if canImport(Darwin) || canImport(Glibc)
#if canImport(Darwin)
os_unfair_lock_unlock(platformLock)
#elseif canImport(Glibc)
let result = pthread_mutex_unlock(platformLock)
assert(result == 0)
#elseif canImport(WinSDK)
Expand Down