| // Copyright 2021 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/timed_mutex.h" |
| |
| #include <algorithm> |
| |
| #include "RTOS.h" |
| #include "pw_assert/check.h" |
| #include "pw_chrono/system_clock.h" |
| #include "pw_chrono_embos/system_clock_constants.h" |
| #include "pw_interrupt/context.h" |
| |
| using pw::chrono::SystemClock; |
| |
| namespace pw::sync { |
| |
| bool TimedMutex::try_lock_for(SystemClock::duration for_at_least) { |
| PW_DCHECK(!interrupt::InInterruptContext()); |
| |
| // Use non-blocking try_lock for negative and zero length durations. |
| if (for_at_least <= SystemClock::duration::zero()) { |
| return try_lock(); |
| } |
| |
| // On a tick based kernel we cannot tell how far along we are on the current |
| // tick, ergo we add one whole tick to the final duration. |
| constexpr SystemClock::duration kMaxTimeoutMinusOne = |
| pw::chrono::embos::kMaxTimeout - SystemClock::duration(1); |
| while (for_at_least > kMaxTimeoutMinusOne) { |
| const int lock_count = OS_UseTimed( |
| &native_handle(), static_cast<OS_TIME>(kMaxTimeoutMinusOne.count())); |
| if (lock_count != 0) { |
| PW_CHECK_UINT_EQ(1, lock_count, "Recursive locking is not permitted"); |
| return true; |
| } |
| for_at_least -= kMaxTimeoutMinusOne; |
| } |
| const int lock_count = OS_UseTimed( |
| &native_handle(), static_cast<OS_TIME>(for_at_least.count() + 1)); |
| PW_CHECK_UINT_LE(1, lock_count, "Recursive locking is not permitted"); |
| return lock_count == 1; |
| } |
| |
| } // namespace pw::sync |