Ken Van Hoeylandt
135 lines
3.3 KiB
C++
135 lines
3.3 KiB
C++
// SPDX-License-Identifier: Apache-2.0
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/**
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* Dispatcher is a thread-safe code execution queue.
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*/
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#pragma once
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#include "EventGroup.h"
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#include "Mutex.h"
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#include "kernel/Kernel.h"
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#ifdef ESP_PLATFORM
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#include <esp_log.h>
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#endif
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#include <functional>
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#include <memory>
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#include <queue>
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namespace tt {
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/**
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* A thread-safe way to defer code execution.
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* Generally, one task would dispatch the execution,
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* while the other thread consumes and executes the work.
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*/
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class Dispatcher final {
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static constexpr auto TAG = "Dispatcher";
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static constexpr EventBits_t BACKPRESSURE_WARNING_COUNT = 100U;
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static constexpr EventBits_t WAIT_FLAG = 1U;
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public:
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typedef std::function<void()> Function;
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private:
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Mutex mutex;
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std::queue<Function> queue = {};
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EventGroup eventFlag;
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bool shutdown = false;
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public:
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explicit Dispatcher() = default;
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~Dispatcher() {
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shutdown = true;
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if (mutex.lock()) {
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mutex.unlock();
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}
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}
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/**
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* Queue a function to be consumed elsewhere.
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* @param[in] function the function to execute elsewhere
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* @param[in] timeout lock acquisition timeout
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* @return true if dispatching was successful (timeout not reached)
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*/
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bool dispatch(Function function, TickType_t timeout = kernel::MAX_TICKS) {
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// Mutate
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if (!mutex.lock(timeout)) {
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#ifdef ESP_PLATFORM
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ESP_LOGE(TAG, "Mutex acquisition timeout");
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#endif
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return false;
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}
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if (shutdown) {
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mutex.unlock();
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return false;
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}
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queue.push(std::move(function));
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if (queue.size() == BACKPRESSURE_WARNING_COUNT) {
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#ifdef ESP_PLATFORM
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ESP_LOGW(TAG, "Backpressure: You're not consuming fast enough (100 queued)");
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#endif
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}
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mutex.unlock();
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if (!eventFlag.set(WAIT_FLAG)) {
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#ifdef ESP_PLATFORM
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ESP_LOGE(TAG, "Failed to set flag");
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#endif
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}
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return true;
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}
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/**
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* Consume 1 or more dispatched functions (if any) until the queue is empty.
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* @warning The timeout is only the wait time before consuming the message! It is not a limit to the total execution time when calling this method.
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* @param[in] timeout the ticks to wait for a message
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* @return the amount of messages that were consumed
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*/
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uint32_t consume(TickType_t timeout = kernel::MAX_TICKS) {
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// Wait for signal
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if (!eventFlag.wait(WAIT_FLAG, false, true, nullptr, timeout)) {
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return 0;
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}
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if (shutdown) {
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return 0;
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}
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// Mutate
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bool processing = true;
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uint32_t consumed = 0;
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do {
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if (mutex.lock(10)) {
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if (!queue.empty()) {
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auto function = queue.front();
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queue.pop();
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consumed++;
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processing = !queue.empty();
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// Don't keep lock as callback might be slow
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mutex.unlock();
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function();
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} else {
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processing = false;
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mutex.unlock();
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}
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} else {
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#ifdef ESP_PLATFORM
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ESP_LOGW(TAG, "Mutex acquisition timeout");
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#endif
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}
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} while (processing && !shutdown);
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return consumed;
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}
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};
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} // namespace
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