mirror of
https://fuchsia.googlesource.com/third_party/pigweed.googlesource.com/pigweed/pigweed
synced 2024-09-20 05:41:06 +00:00
5ff8cc5b2b
The signatures, comments, and docs are updated to reflect the most recent terminology for describing blocking APIs with timeouts and deadlines. Change-Id: Iea7ea5490c44c9ce698a694e532345909bba562f Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/60040 Reviewed-by: Keir Mierle <keir@google.com> Pigweed-Auto-Submit: Ewout van Bekkum <ewout@google.com> Commit-Queue: Ewout van Bekkum <ewout@google.com>
67 lines
2.4 KiB
C++
67 lines
2.4 KiB
C++
// 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/counting_semaphore.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 {
|
|
|
|
void CountingSemaphore::release(ptrdiff_t update) {
|
|
for (; update > 0; --update) {
|
|
// There is no API to atomically detect overflow, however debug builds of
|
|
// embOS call OS_Error() internally when overflow is detected for the native
|
|
// token representation. Rather than enter a critical section both due to
|
|
// cost and potential direct use of the native handle, a lazy check is used
|
|
// for debug builds which may not trigger on the initial overflow.
|
|
PW_DCHECK_UINT_LE(OS_GetCSemaValue(&native_type_),
|
|
CountingSemaphore::max(),
|
|
"Overflowed counting semaphore.");
|
|
OS_SignalCSema(&native_type_);
|
|
}
|
|
}
|
|
|
|
bool CountingSemaphore::try_acquire_for(SystemClock::duration timeout) {
|
|
PW_DCHECK(!interrupt::InInterruptContext());
|
|
|
|
// Use non-blocking try_acquire for negative and zero length durations.
|
|
if (timeout <= SystemClock::duration::zero()) {
|
|
return try_acquire();
|
|
}
|
|
|
|
// 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 (timeout > kMaxTimeoutMinusOne) {
|
|
if (OS_WaitCSemaTimed(&native_type_,
|
|
static_cast<OS_TIME>(kMaxTimeoutMinusOne.count()))) {
|
|
return true;
|
|
}
|
|
timeout -= kMaxTimeoutMinusOne;
|
|
}
|
|
return OS_WaitCSemaTimed(&native_type_,
|
|
static_cast<OS_TIME>(timeout.count() + 1));
|
|
}
|
|
|
|
} // namespace pw::sync
|