| //! A readers-writer lock implementation backed by the SOLID kernel extension. |
| use super::{ |
| abi, |
| itron::{ |
| error::{expect_success, expect_success_aborting, fail, ItronError}, |
| spin::SpinIdOnceCell, |
| }, |
| }; |
| |
| pub struct RwLock { |
| /// The ID of the underlying mutex object |
| rwl: SpinIdOnceCell<()>, |
| } |
| |
| // Safety: `num_readers` is protected by `mtx_num_readers` |
| unsafe impl Send for RwLock {} |
| unsafe impl Sync for RwLock {} |
| |
| fn new_rwl() -> Result<abi::ID, ItronError> { |
| ItronError::err_if_negative(unsafe { abi::rwl_acre_rwl() }) |
| } |
| |
| impl RwLock { |
| #[inline] |
| pub const fn new() -> RwLock { |
| RwLock { rwl: SpinIdOnceCell::new() } |
| } |
| |
| /// Get the inner mutex's ID, which is lazily created. |
| fn raw(&self) -> abi::ID { |
| match self.rwl.get_or_try_init(|| new_rwl().map(|id| (id, ()))) { |
| Ok((id, ())) => id, |
| Err(e) => fail(e, &"rwl_acre_rwl"), |
| } |
| } |
| |
| #[inline] |
| pub fn read(&self) { |
| let rwl = self.raw(); |
| expect_success(unsafe { abi::rwl_loc_rdl(rwl) }, &"rwl_loc_rdl"); |
| } |
| |
| #[inline] |
| pub fn try_read(&self) -> bool { |
| let rwl = self.raw(); |
| match unsafe { abi::rwl_ploc_rdl(rwl) } { |
| abi::E_TMOUT => false, |
| er => { |
| expect_success(er, &"rwl_ploc_rdl"); |
| true |
| } |
| } |
| } |
| |
| #[inline] |
| pub fn write(&self) { |
| let rwl = self.raw(); |
| expect_success(unsafe { abi::rwl_loc_wrl(rwl) }, &"rwl_loc_wrl"); |
| } |
| |
| #[inline] |
| pub fn try_write(&self) -> bool { |
| let rwl = self.raw(); |
| match unsafe { abi::rwl_ploc_wrl(rwl) } { |
| abi::E_TMOUT => false, |
| er => { |
| expect_success(er, &"rwl_ploc_wrl"); |
| true |
| } |
| } |
| } |
| |
| #[inline] |
| pub unsafe fn read_unlock(&self) { |
| let rwl = self.raw(); |
| expect_success_aborting(unsafe { abi::rwl_unl_rwl(rwl) }, &"rwl_unl_rwl"); |
| } |
| |
| #[inline] |
| pub unsafe fn write_unlock(&self) { |
| let rwl = self.raw(); |
| expect_success_aborting(unsafe { abi::rwl_unl_rwl(rwl) }, &"rwl_unl_rwl"); |
| } |
| } |
| |
| impl Drop for RwLock { |
| #[inline] |
| fn drop(&mut self) { |
| if let Some(rwl) = self.rwl.get().map(|x| x.0) { |
| expect_success_aborting(unsafe { abi::rwl_del_rwl(rwl) }, &"rwl_del_rwl"); |
| } |
| } |
| } |