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| 1 | +// Licensed to the Apache Software Foundation (ASF) under one |
| 2 | +// or more contributor license agreements. See the NOTICE file |
| 3 | +// distributed with this work for additional information |
| 4 | +// regarding copyright ownership. The ASF licenses this file |
| 5 | +// to you under the Apache License, Version 2.0 (the |
| 6 | +// "License"); you may not use this file except in compliance |
| 7 | +// with the License. You may obtain a copy of the License at |
| 8 | +// |
| 9 | +// http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | +// |
| 11 | +// Unless required by applicable law or agreed to in writing, |
| 12 | +// software distributed under the License is distributed on an |
| 13 | +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| 14 | +// KIND, either express or implied. See the License for the |
| 15 | +// specific language governing permissions and limitations |
| 16 | +// under the License.. |
| 17 | + |
| 18 | +use crate::sync::lock_api::RawMutex; |
| 19 | +use crate::tcs; |
| 20 | +use core::cell::UnsafeCell; |
| 21 | +use core::convert::From; |
| 22 | +use core::fmt; |
| 23 | +use core::hint; |
| 24 | +use core::mem; |
| 25 | +use core::ops::{Deref, DerefMut}; |
| 26 | +use core::sync::atomic::{AtomicBool, AtomicUsize, Ordering}; |
| 27 | +use sgx_types::marker::ContiguousMemory; |
| 28 | + |
| 29 | +pub struct SpinReentrantMutex<T: ?Sized> { |
| 30 | + lock: AtomicBool, |
| 31 | + owner: AtomicUsize, // tcs id |
| 32 | + count: UnsafeCell<u32>, |
| 33 | + data: UnsafeCell<T>, |
| 34 | +} |
| 35 | + |
| 36 | +unsafe impl<T: ContiguousMemory> ContiguousMemory for SpinReentrantMutex<T> {} |
| 37 | + |
| 38 | +unsafe impl<T: ?Sized + Sync> Sync for SpinReentrantMutex<T> {} |
| 39 | +unsafe impl<T: ?Sized + Send> Send for SpinReentrantMutex<T> {} |
| 40 | + |
| 41 | +impl<T> SpinReentrantMutex<T> { |
| 42 | + pub const fn new(data: T) -> Self { |
| 43 | + Self { |
| 44 | + lock: AtomicBool::new(false), |
| 45 | + owner: AtomicUsize::new(0), |
| 46 | + count: UnsafeCell::new(0), |
| 47 | + data: UnsafeCell::new(data), |
| 48 | + } |
| 49 | + } |
| 50 | + |
| 51 | + #[inline] |
| 52 | + pub fn into_inner(self) -> T { |
| 53 | + let SpinReentrantMutex { data, .. } = self; |
| 54 | + data.into_inner() |
| 55 | + } |
| 56 | +} |
| 57 | + |
| 58 | +impl<T: ?Sized> SpinReentrantMutex<T> { |
| 59 | + #[inline] |
| 60 | + pub fn lock(&self) -> SpinReentrantMutexGuard<'_, T> { |
| 61 | + let current_thread = tcs::current().id().as_usize(); |
| 62 | + if self.owner.load(Ordering::Relaxed) == current_thread { |
| 63 | + self.increment_count() |
| 64 | + } else { |
| 65 | + self.acquire_lock(); |
| 66 | + self.owner.store(current_thread, Ordering::Relaxed); |
| 67 | + unsafe { |
| 68 | + assert_eq!(*self.count.get(), 0); |
| 69 | + *self.count.get() = 1; |
| 70 | + } |
| 71 | + } |
| 72 | + |
| 73 | + SpinReentrantMutexGuard { lock: self } |
| 74 | + } |
| 75 | + |
| 76 | + #[inline] |
| 77 | + pub fn try_lock(&self) -> Option<SpinReentrantMutexGuard<'_, T>> { |
| 78 | + if self.try_acquire_lock() { |
| 79 | + Some(SpinReentrantMutexGuard { lock: self }) |
| 80 | + } else { |
| 81 | + None |
| 82 | + } |
| 83 | + } |
| 84 | + |
| 85 | + #[inline] |
| 86 | + pub fn unlock(guard: SpinReentrantMutexGuard<'_, T>) { |
| 87 | + drop(guard); |
| 88 | + } |
| 89 | + |
| 90 | + #[inline] |
| 91 | + pub unsafe fn force_unlock(&self) { |
| 92 | + self.lock.store(false, Ordering::Release); |
| 93 | + } |
| 94 | + |
| 95 | + #[inline] |
| 96 | + pub fn get_mut(&mut self) -> &mut T { |
| 97 | + unsafe { &mut *self.data.get() } |
| 98 | + } |
| 99 | + |
| 100 | + #[inline] |
| 101 | + pub fn is_locked(&self) -> bool { |
| 102 | + self.lock.load(Ordering::Relaxed) |
| 103 | + } |
| 104 | + |
| 105 | + #[inline] |
| 106 | + fn increment_count(&self) { |
| 107 | + unsafe { |
| 108 | + *self.count.get() = (*self.count.get()) |
| 109 | + .checked_add(1) |
| 110 | + .expect("lock count overflow in reentrant mutex"); |
| 111 | + } |
| 112 | + } |
| 113 | + |
| 114 | + #[inline] |
| 115 | + fn acquire_lock(&self) { |
| 116 | + while self |
| 117 | + .lock |
| 118 | + .compare_exchange_weak(false, true, Ordering::Acquire, Ordering::Relaxed) |
| 119 | + .is_err() |
| 120 | + { |
| 121 | + while self.is_locked() { |
| 122 | + hint::spin_loop(); |
| 123 | + } |
| 124 | + } |
| 125 | + } |
| 126 | + |
| 127 | + #[inline] |
| 128 | + fn try_acquire_lock(&self) -> bool { |
| 129 | + self.lock |
| 130 | + .compare_exchange(false, true, Ordering::Acquire, Ordering::Relaxed) |
| 131 | + .is_ok() |
| 132 | + } |
| 133 | +} |
| 134 | + |
| 135 | +impl<T: ?Sized + fmt::Debug> fmt::Debug for SpinReentrantMutex<T> { |
| 136 | + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| 137 | + match self.try_lock() { |
| 138 | + Some(guard) => write!(f, "SpinReentrantMutex {{ value: ") |
| 139 | + .and_then(|()| (*guard).fmt(f)) |
| 140 | + .and_then(|()| write!(f, "}}")), |
| 141 | + None => write!(f, "SpinReentrantMutex {{ <locked> }}"), |
| 142 | + } |
| 143 | + } |
| 144 | +} |
| 145 | + |
| 146 | +impl<T: ?Sized + Default> Default for SpinReentrantMutex<T> { |
| 147 | + fn default() -> SpinReentrantMutex<T> { |
| 148 | + SpinReentrantMutex::new(Default::default()) |
| 149 | + } |
| 150 | +} |
| 151 | + |
| 152 | +impl<T> From<T> for SpinReentrantMutex<T> { |
| 153 | + fn from(value: T) -> SpinReentrantMutex<T> { |
| 154 | + SpinReentrantMutex::new(value) |
| 155 | + } |
| 156 | +} |
| 157 | + |
| 158 | +impl<T> RawMutex for SpinReentrantMutex<T> { |
| 159 | + #[inline] |
| 160 | + fn lock(&self) { |
| 161 | + mem::forget(SpinReentrantMutex::lock(self)); |
| 162 | + } |
| 163 | + |
| 164 | + #[inline] |
| 165 | + fn try_lock(&self) -> bool { |
| 166 | + SpinReentrantMutex::try_lock(self) |
| 167 | + .map(mem::forget) |
| 168 | + .is_some() |
| 169 | + } |
| 170 | + |
| 171 | + #[inline] |
| 172 | + unsafe fn unlock(&self) { |
| 173 | + self.force_unlock(); |
| 174 | + } |
| 175 | +} |
| 176 | + |
| 177 | +pub struct SpinReentrantMutexGuard<'a, T: 'a + ?Sized> { |
| 178 | + lock: &'a SpinReentrantMutex<T>, |
| 179 | +} |
| 180 | + |
| 181 | +impl<T: ?Sized> !Send for SpinReentrantMutexGuard<'_, T> {} |
| 182 | +unsafe impl<T: ?Sized + Sync> Sync for SpinReentrantMutexGuard<'_, T> {} |
| 183 | + |
| 184 | +impl<T: ?Sized> Drop for SpinReentrantMutexGuard<'_, T> { |
| 185 | + fn drop(&mut self) { |
| 186 | + let remutx = self.lock; |
| 187 | + unsafe { |
| 188 | + *remutx.count.get() -= 1; |
| 189 | + if *remutx.count.get() == 0 { |
| 190 | + remutx.owner.store(0, Ordering::Relaxed); |
| 191 | + remutx.lock.store(false, Ordering::Release); |
| 192 | + } |
| 193 | + } |
| 194 | + } |
| 195 | +} |
| 196 | + |
| 197 | +impl<T: ?Sized> Deref for SpinReentrantMutexGuard<'_, T> { |
| 198 | + type Target = T; |
| 199 | + fn deref(&self) -> &Self::Target { |
| 200 | + unsafe { &*self.lock.data.get() } |
| 201 | + } |
| 202 | +} |
| 203 | + |
| 204 | +impl<T: ?Sized> DerefMut for SpinReentrantMutexGuard<'_, T> { |
| 205 | + fn deref_mut(&mut self) -> &mut Self::Target { |
| 206 | + unsafe { &mut *self.lock.data.get() } |
| 207 | + } |
| 208 | +} |
| 209 | + |
| 210 | +impl<T: ?Sized + fmt::Debug> fmt::Debug for SpinReentrantMutexGuard<'_, T> { |
| 211 | + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| 212 | + fmt::Debug::fmt(&**self, f) |
| 213 | + } |
| 214 | +} |
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