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