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https://fuchsia.googlesource.com/third_party/pigweed.googlesource.com/pigweed/pigweed
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39144b6f0f
Adds documentation covering thread identification, yielding, sleeping, and portable thread creation. The signatures, comments, and docs are updated to reflect the most recent terminology for describing blocking APIs with timeouts and deadlines. Change-Id: I5d802335d3e52416131ad437ef8bfa19e04e637b Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/60042 Reviewed-by: Keir Mierle <keir@google.com> Pigweed-Auto-Submit: Ewout van Bekkum <ewout@google.com> Commit-Queue: Ewout van Bekkum <ewout@google.com>
60 lines
2.2 KiB
C++
60 lines
2.2 KiB
C++
// Copyright 2020 The Pigweed Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy of
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// the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations under
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// the License.
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#include "pw_thread/sleep.h"
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#include <algorithm>
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#include "pw_assert/check.h"
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#include "pw_chrono/system_clock.h"
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#include "pw_chrono_threadx/system_clock_constants.h"
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#include "pw_thread/id.h"
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#include "tx_api.h"
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using pw::chrono::SystemClock;
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namespace pw::this_thread {
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void sleep_for(chrono::SystemClock::duration sleep_duration) {
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// Ensure this is being called by a thread.
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PW_DCHECK(get_id() != thread::Id());
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// Yield for negative and zero length durations.
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if (sleep_duration <= chrono::SystemClock::duration::zero()) {
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tx_thread_relinquish();
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return;
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}
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// In case the timeout is too long for us to express through the native
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// ThreadX API, we repeatedly wait with shorter durations. Note that on a tick
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// based kernel we cannot tell how far along we are on the current tick, ergo
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// we add one whole tick to the final duration. However, this also means that
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// the loop must ensure that timeout + 1 is less than the max timeout.
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constexpr SystemClock::duration kMaxTimeoutMinusOne =
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pw::chrono::threadx::kMaxTimeout - SystemClock::duration(1);
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while (sleep_duration > kMaxTimeoutMinusOne) {
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const UINT result =
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tx_thread_sleep(static_cast<ULONG>(kMaxTimeoutMinusOne.count()));
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PW_CHECK_UINT_EQ(TX_SUCCESS, result);
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sleep_duration -= kMaxTimeoutMinusOne;
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}
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// On a tick based kernel we cannot tell how far along we are on the current
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// tick, ergo we add one whole tick to the final duration.
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const UINT result =
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tx_thread_sleep(static_cast<ULONG>(sleep_duration.count() + 1));
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PW_CHECK_UINT_EQ(TX_SUCCESS, result);
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}
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} // namespace pw::this_thread
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