| // Copyright 2020 The Pigweed Authors |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| // use this file except in compliance with the License. You may obtain a copy of |
| // the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| // License for the specific language governing permissions and limitations under |
| // the License. |
| |
| #include "pw_sync/thread_notification.h" |
| |
| #include <mutex> |
| |
| #include "pw_assert/check.h" |
| #include "pw_interrupt/context.h" |
| #include "pw_sync/interrupt_spin_lock.h" |
| #include "tx_api.h" |
| |
| namespace pw::sync { |
| namespace backend { |
| |
| InterruptSpinLock thread_notification_isl; |
| |
| } // namespace backend |
| |
| void ThreadNotification::acquire() { |
| // Enforce the pw::sync::ThreadNotification IRQ contract. |
| PW_DCHECK(!interrupt::InInterruptContext()); |
| |
| // Enforce that only a single thread can block at a time. |
| PW_DCHECK(native_type_.blocked_thread == nullptr); |
| |
| { |
| std::lock_guard lock(backend::thread_notification_isl); |
| if (native_type_.notified) { |
| native_type_.notified = false; |
| return; |
| } |
| // Not notified yet, register the thread for a one-time notification. |
| native_type_.blocked_thread = tx_thread_identify(); |
| } |
| |
| PW_CHECK_UINT_EQ(tx_thread_sleep(TX_WAIT_FOREVER), TX_WAIT_ABORTED); |
| { |
| // The thread pointer was cleared by the notifier. |
| // Note that this may hide another notification, however this is considered |
| // a form of notification saturation just like as if this happened before |
| // acquire() was invoked. |
| std::lock_guard lock(backend::thread_notification_isl); |
| native_type_.notified = false; |
| } |
| } |
| |
| } // namespace pw::sync |