From d3bc8b552c9bd5a0a88bdc40b71e09ec8c149cb7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niccol=C3=B2=20Betto?= <niccolo.betto@skywarder.eu>
Date: Wed, 28 Dec 2022 16:28:24 +0100
Subject: [PATCH] [TaskScheduler] Store tasks in a preallocated `std::vector`
The tasks vector is resized to MAX_TASKS (256 at the time of writing
this) immediately after construction to avoid reallocations.
---
src/shared/scheduler/TaskScheduler.cpp | 58 ++++++++++----------------
src/shared/scheduler/TaskScheduler.h | 19 ++++-----
2 files changed, 30 insertions(+), 47 deletions(-)
diff --git a/src/shared/scheduler/TaskScheduler.cpp b/src/shared/scheduler/TaskScheduler.cpp
index 5b41ac35c..44f5f363d 100644
--- a/src/shared/scheduler/TaskScheduler.cpp
+++ b/src/shared/scheduler/TaskScheduler.cpp
@@ -40,47 +40,33 @@ static constexpr unsigned int MS_PER_TICK =
} // namespace Constants
TaskScheduler::TaskScheduler(miosix::Priority priority)
- : ActiveObject(STACK_MIN_FOR_SKYWARD, priority)
+ : ActiveObject(STACK_MIN_FOR_SKYWARD, priority), tasks()
{
- // Create dynamically the tasks vector because of too much space
- tasks = new std::array<Task, TASKS_SIZE>();
+ // Preallocate the vector to avoid dynamic allocation later on
+ tasks.reserve(MAX_TASKS);
- // Initialize the vector elements
- for (size_t i = 1; i < TASKS_SIZE; i++)
- {
- (*tasks)[i] = Task();
- }
+ // Reserve the zeroth element so that the task ID is never zero, for
+ // API compatibility: returned value from addTask() is zero on error.
+ tasks.emplace_back();
}
-TaskScheduler::~TaskScheduler() { delete tasks; }
-
size_t TaskScheduler::addTask(function_t function, uint32_t period,
Policy policy, int64_t startTick)
{
Lock<FastMutex> lock(mutex);
- size_t id = 1;
-
- // Find a suitable id for the new task
- for (; id < TASKS_SIZE; id++)
- {
- if ((*tasks)[id].empty())
- {
- break;
- }
- }
- // Check if in the corresponding id there's already a task
- if ((*tasks)[id].enabled)
+ if (tasks.size() >= MAX_TASKS)
{
- // Unlock the mutex for expensive operation
+ // Unlock the mutex to release the scheduler resources before logging
Unlock<FastMutex> unlock(mutex);
- LOG_ERR(logger, "Full task scheduler, id = {:zu}", id);
+ LOG_ERR(logger, "Full task scheduler");
return 0;
}
- // Create a new task with the given parameters
- (*tasks)[id] = Task(function, period, policy);
+ // Insert a new task with the given parameters
+ tasks.emplace_back(function, period, policy);
+ size_t id = tasks.size() - 1;
if (policy == Policy::ONE_SHOT)
{
@@ -96,14 +82,14 @@ size_t TaskScheduler::addTask(function_t function, uint32_t period,
void TaskScheduler::enableTask(size_t id)
{
- if (id > TASKS_SIZE)
+ if (id > tasks.size() - 1)
{
LOG_ERR(logger, "Tried to enable an out-of-range task, id = {}", id);
return;
}
Lock<FastMutex> lock(mutex);
- Task& task = (*tasks)[id];
+ Task& task = tasks[id];
// Check that the task function is not empty
// Attempting to run an empty function will throw a bad_function_call
@@ -122,14 +108,14 @@ void TaskScheduler::enableTask(size_t id)
void TaskScheduler::disableTask(size_t id)
{
- if (id > TASKS_SIZE)
+ if (id > tasks.size() - 1)
{
LOG_ERR(logger, "Tried to disable an out-of-range task, id = {}", id);
return;
}
Lock<FastMutex> lock(mutex);
- (*tasks)[id].enabled = false;
+ tasks[id].enabled = false;
}
bool TaskScheduler::start()
@@ -161,9 +147,9 @@ vector<TaskStatsResult> TaskScheduler::getTaskStats()
vector<TaskStatsResult> result;
- for (size_t id = 1; id < TASKS_SIZE; id++)
+ for (size_t id = 1; id < tasks.size(); id++)
{
- const Task& task = (*tasks)[id];
+ const Task& task = tasks[id];
if (task.enabled)
{
result.push_back(fromTaskIdPairToStatsResult(task, id));
@@ -185,7 +171,7 @@ void TaskScheduler::normalizeTasks()
if (event.nextTick < currentTick)
{
- Task& task = (*tasks)[event.taskId];
+ Task& task = tasks[event.taskId];
event.nextTick +=
((currentTick - event.nextTick) / task.period + 1) *
task.period;
@@ -213,7 +199,7 @@ void TaskScheduler::run()
int64_t startTick = getTick();
Event nextEvent = agenda.top();
- Task& nextTask = (*tasks)[nextEvent.taskId];
+ Task& nextTask = tasks[nextEvent.taskId];
// If the task has the SKIP policy and its execution was missed, we need
// to move it forward to match the period
@@ -260,7 +246,7 @@ void TaskScheduler::run()
void TaskScheduler::updateStats(const Event& event, int64_t startTick,
int64_t endTick)
{
- Task& task = (*tasks)[event.taskId];
+ Task& task = tasks[event.taskId];
// Activation stats
float activationError = startTick - event.nextTick;
@@ -281,7 +267,7 @@ void TaskScheduler::updateStats(const Event& event, int64_t startTick,
void TaskScheduler::enqueue(Event event, int64_t startTick)
{
- Task& task = (*tasks)[event.taskId];
+ Task& task = tasks[event.taskId];
switch (task.policy)
{
case Policy::ONE_SHOT:
diff --git a/src/shared/scheduler/TaskScheduler.h b/src/shared/scheduler/TaskScheduler.h
index b4a275939..b7e83e496 100644
--- a/src/shared/scheduler/TaskScheduler.h
+++ b/src/shared/scheduler/TaskScheduler.h
@@ -63,9 +63,9 @@ public:
using function_t = std::function<void()>;
/**
- * @brief It defines the tasks array maximum size
+ * @brief The maximum number of tasks the scheduler can handle.
*/
- static constexpr size_t TASKS_SIZE = 256;
+ static constexpr size_t MAX_TASKS = 256;
/**
* @brief Task behavior policy.
@@ -98,14 +98,10 @@ public:
explicit TaskScheduler(miosix::Priority priority = miosix::PRIORITY_MAX -
1);
- ~TaskScheduler();
-
/**
- * @brief Add a task function to the scheduler with an auto generated id.
+ * @brief Add a task function to the scheduler with an auto generated ID.
*
* Note that each task has it's own unique ID, even one shot tasks!
- * Therefore, if a task already exists with the same id, the function will
- * fail and return false.
*
* For one shot tasks, the period is used as a delay. If 0 the task will be
* executed immediately, otherwise after the given period.
@@ -114,7 +110,7 @@ public:
* @param period Inter call period [ms].
* @param policy Task policy, default is SKIP.
* @param startTick First activation time, useful for synchronizing tasks.
- * @return true if the task was added successfully.
+ * @return The ID of the task if it was added successfully, 0 otherwise.
*/
size_t addTask(function_t function, uint32_t period,
Policy policy = Policy::SKIP,
@@ -252,9 +248,10 @@ private:
}
miosix::FastMutex mutex; ///< Mutex to protect tasks and agenda.
- std::array<Task, TASKS_SIZE>* tasks; ///< Holds all tasks to be scheduled.
- miosix::ConditionVariable condvar; ///< Used when agenda is empty.
- EventQueue agenda; ///< Ordered list of functions.
+ std::vector<Task> tasks; ///< Holds all tasks to be scheduled, preallocated
+ ///< to MAX_TASKS avoid dynamic allocations.
+ miosix::ConditionVariable condvar; ///< Used when agenda is empty.
+ EventQueue agenda; ///< Ordered list of functions.
PrintLogger logger = Logging::getLogger("taskscheduler");
};
--
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