forked from ROMEO/obsw
73 lines
2.0 KiB
Rust
73 lines
2.0 KiB
Rust
use core::slice::SliceIndex;
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use crate::check_global_threading_available;
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trait StoreBackend {
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fn free_slot(&mut self, length: usize) -> Option<*mut [u8]>;
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}
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struct Store<'a> {
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mutex: crate::fsrc::mutex::RawMutex,
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backend: &'a mut dyn StoreBackend,
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}
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impl<'a> Store<'a> {
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pub fn accessor(&mut self) -> StoreAccessor {
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check_global_threading_available!();
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// holy shit, this is really unsafe, even for us:
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// we cast away the lifetime
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// this is safe as we only do it in threading
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// and the Accessor will only use it while still in threading
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// (the accessor is a smart pointer refusing to be smart outside
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// of threading)
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let static_pointer = unsafe { core::mem::transmute::<*mut Store<'a>, *mut Store<'static>>(self) };
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StoreAccessor {
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store: static_pointer,
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}
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}
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fn free_slot(&mut self, length: usize) -> Result<StoreSlot, ()> {
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if let Ok(_guard) = self.mutex.take() {
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if let Some(data) = self.backend.free_slot(length){
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Ok(StoreSlot { data: data })
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} else {
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Err(())
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}
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} else {
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Err(())
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}
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}
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}
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// TODO needs to be able to be uninitialized as it should be usable as member
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// A smart pointer to a Store protecting insane (static) pointer usage
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// only works during threading, panics otherwise
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struct StoreAccessor {
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store: *mut Store<'static>,
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}
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impl StoreAccessor {
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fn free_slot(&self, length: usize) -> Result<StoreSlot, ()> {
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check_global_threading_available!();
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unsafe { (*self.store).free_slot(length) }
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}
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}
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struct StoreSlot {
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data: *mut [u8],
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}
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impl StoreSlot {
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pub fn get<I>(&self, index: I) -> &mut [u8]
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where I: SliceIndex<u8>
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{
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check_global_threading_available!();
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unsafe { &mut (*self.data) }
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}
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pub fn get_all(&self) -> &mut [u8] {
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check_global_threading_available!();
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unsafe { &mut (*self.data) }
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}
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}
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