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Extract platform-specific QoS code into module

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Luna Razzaghipour 2023-05-21 02:27:49 +10:00
parent bb02ae7532
commit a416248296
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1 changed files with 95 additions and 80 deletions
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175
crates/stdx/src/thread.rs
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@ -207,105 +207,120 @@ pub enum QoSClass {
UserInteractive, UserInteractive,
} }
#[cfg(target_vendor = "apple")] pub const IS_QOS_AVAILABLE: bool = imp::IS_QOS_AVAILABLE;
pub const IS_QOS_AVAILABLE: bool = true;
#[cfg(not(target_vendor = "apple"))] pub fn set_current_thread_qos_class(class: QoSClass) {
pub const IS_QOS_AVAILABLE: bool = false; imp::set_current_thread_qos_class(class)
}
pub fn get_current_thread_qos_class() -> Option<QoSClass> {
imp::get_current_thread_qos_class()
}
// All Apple platforms use XNU as their kernel // All Apple platforms use XNU as their kernel
// and thus have the concept of QoS. // and thus have the concept of QoS.
#[cfg(target_vendor = "apple")] #[cfg(target_vendor = "apple")]
pub fn set_current_thread_qos_class(class: QoSClass) { mod imp {
let c = match class { use super::QoSClass;
QoSClass::UserInteractive => libc::qos_class_t::QOS_CLASS_USER_INTERACTIVE,
QoSClass::UserInitiated => libc::qos_class_t::QOS_CLASS_USER_INITIATED,
QoSClass::Utility => libc::qos_class_t::QOS_CLASS_UTILITY,
QoSClass::Background => libc::qos_class_t::QOS_CLASS_BACKGROUND,
};
let code = unsafe { libc::pthread_set_qos_class_self_np(c, 0) }; pub(super) const IS_QOS_AVAILABLE: bool = true;
if code == 0 { pub(super) fn set_current_thread_qos_class(class: QoSClass) {
return; let c = match class {
} QoSClass::UserInteractive => libc::qos_class_t::QOS_CLASS_USER_INTERACTIVE,
QoSClass::UserInitiated => libc::qos_class_t::QOS_CLASS_USER_INITIATED,
QoSClass::Utility => libc::qos_class_t::QOS_CLASS_UTILITY,
QoSClass::Background => libc::qos_class_t::QOS_CLASS_BACKGROUND,
};
let errno = unsafe { *libc::__error() }; let code = unsafe { libc::pthread_set_qos_class_self_np(c, 0) };
match errno { if code == 0 {
libc::EPERM => { return;
// This thread has been excluded from the QoS system
// due to a previous call to a function such as `pthread_setschedparam`
// which is incompatible with QoS.
//
// Panic instead of returning an error
// to maintain the invariant that we only use QoS APIs.
panic!("tried to set QoS of thread which has opted out of QoS (os error {errno})")
} }
libc::EINVAL => {
// This is returned if we pass something other than a qos_class_t
// to `pthread_set_qos_class_self_np`.
//
// This is impossible, so again panic.
unreachable!("invalid qos_class_t value was passed to pthread_set_qos_class_self_np")
}
_ => {
// `pthread_set_qos_class_self_np`’s documentation
// does not mention any other errors.
unreachable!("`pthread_set_qos_class_self_np` returned unexpected error {errno}")
}
}
}
#[cfg(not(target_vendor = "apple"))]
pub fn set_current_thread_qos_class(class: QoSClass) {
// FIXME: Windows has QoS APIs, we should use them!
}
#[cfg(target_vendor = "apple")]
pub fn get_current_thread_qos_class() -> Option<QoSClass> {
let current_thread = unsafe { libc::pthread_self() };
let mut qos_class_raw = libc::qos_class_t::QOS_CLASS_UNSPECIFIED;
let code = unsafe {
libc::pthread_get_qos_class_np(current_thread, &mut qos_class_raw, std::ptr::null_mut())
};
if code != 0 {
// `pthread_get_qos_class_np`’s documentation states that
// an error value is placed into errno if the return code is not zero.
// However, it never states what errors are possible.
// Inspecting the source[0] shows that, as of this writing, it always returns zero.
//
// Whatever errors the function could report in future are likely to be
// ones which we cannot handle anyway
//
// 0: https://github.com/apple-oss-distributions/libpthread/blob/67e155c94093be9a204b69637d198eceff2c7c46/src/qos.c#L171-L177
let errno = unsafe { *libc::__error() }; let errno = unsafe { *libc::__error() };
unreachable!("`pthread_get_qos_class_np` failed unexpectedly (os error {errno})");
match errno {
libc::EPERM => {
// This thread has been excluded from the QoS system
// due to a previous call to a function such as `pthread_setschedparam`
// which is incompatible with QoS.
//
// Panic instead of returning an error
// to maintain the invariant that we only use QoS APIs.
panic!("tried to set QoS of thread which has opted out of QoS (os error {errno})")
}
libc::EINVAL => {
// This is returned if we pass something other than a qos_class_t
// to `pthread_set_qos_class_self_np`.
//
// This is impossible, so again panic.
unreachable!(
"invalid qos_class_t value was passed to pthread_set_qos_class_self_np"
)
}
_ => {
// `pthread_set_qos_class_self_np`’s documentation
// does not mention any other errors.
unreachable!("`pthread_set_qos_class_self_np` returned unexpected error {errno}")
}
}
} }
match qos_class_raw { pub(super) fn get_current_thread_qos_class() -> Option<QoSClass> {
libc::qos_class_t::QOS_CLASS_USER_INTERACTIVE => Some(QoSClass::UserInteractive), let current_thread = unsafe { libc::pthread_self() };
libc::qos_class_t::QOS_CLASS_USER_INITIATED => Some(QoSClass::UserInitiated), let mut qos_class_raw = libc::qos_class_t::QOS_CLASS_UNSPECIFIED;
libc::qos_class_t::QOS_CLASS_DEFAULT => None, // QoS has never been set let code = unsafe {
libc::qos_class_t::QOS_CLASS_UTILITY => Some(QoSClass::Utility), libc::pthread_get_qos_class_np(current_thread, &mut qos_class_raw, std::ptr::null_mut())
libc::qos_class_t::QOS_CLASS_BACKGROUND => Some(QoSClass::Background), };
libc::qos_class_t::QOS_CLASS_UNSPECIFIED => { if code != 0 {
// Using manual scheduling APIs causes threads to “opt out” of QoS. // `pthread_get_qos_class_np`’s documentation states that
// At this point they become incompatible with QoS, // an error value is placed into errno if the return code is not zero.
// and as such have the “unspecified” QoS class. // However, it never states what errors are possible.
// Inspecting the source[0] shows that, as of this writing, it always returns zero.
// //
// Panic instead of returning an error // Whatever errors the function could report in future are likely to be
// to maintain the invariant that we only use QoS APIs. // ones which we cannot handle anyway
panic!("tried to get QoS of thread which has opted out of QoS") //
// 0: https://github.com/apple-oss-distributions/libpthread/blob/67e155c94093be9a204b69637d198eceff2c7c46/src/qos.c#L171-L177
let errno = unsafe { *libc::__error() };
unreachable!("`pthread_get_qos_class_np` failed unexpectedly (os error {errno})");
}
match qos_class_raw {
libc::qos_class_t::QOS_CLASS_USER_INTERACTIVE => Some(QoSClass::UserInteractive),
libc::qos_class_t::QOS_CLASS_USER_INITIATED => Some(QoSClass::UserInitiated),
libc::qos_class_t::QOS_CLASS_DEFAULT => None, // QoS has never been set
libc::qos_class_t::QOS_CLASS_UTILITY => Some(QoSClass::Utility),
libc::qos_class_t::QOS_CLASS_BACKGROUND => Some(QoSClass::Background),
libc::qos_class_t::QOS_CLASS_UNSPECIFIED => {
// Using manual scheduling APIs causes threads to “opt out” of QoS.
// At this point they become incompatible with QoS,
// and as such have the “unspecified” QoS class.
//
// Panic instead of returning an error
// to maintain the invariant that we only use QoS APIs.
panic!("tried to get QoS of thread which has opted out of QoS")
}
} }
} }
} }
// FIXME: Windows has QoS APIs, we should use them!
#[cfg(not(target_vendor = "apple"))] #[cfg(not(target_vendor = "apple"))]
pub fn get_current_thread_qos_class() -> Option<QoSClass> { mod imp {
None use super::QoSClass;
pub(super) const IS_QOS_AVAILABLE: bool = false;
pub(super) fn set_current_thread_qos_class(_: QoSClass) {}
pub(super) fn get_current_thread_qos_class() -> Option<QoSClass> {
None
}
} }