From 6564d6e81dc26226c515a23f41a48f6183ddf682 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] Pre-allocate the agenda's backing vector
Avoids runtime re-allocations by reserving the
maximum capacity at construction time.
---
src/shared/scheduler/TaskScheduler.cpp | 67 +++++++++++++++-----------
src/shared/scheduler/TaskScheduler.h | 33 +++++++++----
2 files changed, 62 insertions(+), 38 deletions(-)
diff --git a/src/shared/scheduler/TaskScheduler.cpp b/src/shared/scheduler/TaskScheduler.cpp
index 035233b37..3e52a5342 100644
--- a/src/shared/scheduler/TaskScheduler.cpp
+++ b/src/shared/scheduler/TaskScheduler.cpp
@@ -31,6 +31,7 @@ using namespace miosix;
namespace Boardcore
{
+
namespace Constants
{
static constexpr unsigned int TICKS_PER_MS =
@@ -39,8 +40,16 @@ static constexpr unsigned int MS_PER_TICK =
1000 / miosix::TICK_FREQ; // Number of milliseconds in a tick
} // namespace Constants
+TaskScheduler::EventQueue TaskScheduler::makeAgenda()
+{
+ std::vector<Event> agendaStorage{};
+ agendaStorage.reserve(MAX_TASKS);
+ return EventQueue{std::greater<Event>{}, std::move(agendaStorage)};
+}
+
TaskScheduler::TaskScheduler(miosix::Priority priority)
- : ActiveObject(STACK_MIN_FOR_SKYWARD, priority), tasks()
+ : ActiveObject(STACK_MIN_FOR_SKYWARD, priority), tasks(),
+ agenda(makeAgenda())
{
// Preallocate the vector to avoid dynamic allocation later on
tasks.reserve(MAX_TASKS);
@@ -65,17 +74,21 @@ size_t TaskScheduler::addTask(function_t function, uint32_t period,
return 0;
}
- // 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)
{
startTick += period;
}
- // Add the task first event in the agenda, performs in-place construction
- agenda.emplace(id, startTick);
+ // Insert a new task with the given parameters
+ tasks.emplace_back(function, period, policy, startTick);
+ size_t id = tasks.size() - 1;
+
+ // Only add the task to the agenda if the scheduler is running
+ // Otherwise, the agenda will be populated when the scheduler is started
+ if (isRunning())
+ {
+ agenda.emplace(id, startTick);
+ }
condvar.broadcast(); // Signals the run thread
mutex.unlock();
@@ -131,8 +144,8 @@ bool TaskScheduler::start()
return false;
}
- // Normalize the tasks start time if they precede the current tick
- normalizeTasks();
+ // Populate the agenda with the tasks we have so far
+ populateAgenda();
return ActiveObject::start();
}
@@ -163,27 +176,24 @@ vector<TaskStatsResult> TaskScheduler::getTaskStats()
return result;
}
-void TaskScheduler::normalizeTasks()
+void TaskScheduler::populateAgenda()
{
int64_t currentTick = getTick();
- EventQueue newAgenda;
- while (!agenda.empty())
+ for (size_t id = 1; id < tasks.size(); id++)
{
- Event event = agenda.top();
- agenda.pop();
+ Task& task = tasks[id];
- if (event.nextTick < currentTick)
+ int64_t nextTick = task.startTick;
+ // Normalize the tasks start time if they precede the current tick
+ if (nextTick < currentTick)
{
- Task& task = tasks[event.taskId];
- event.nextTick +=
- ((currentTick - event.nextTick) / task.period + 1) *
- task.period;
+ nextTick +=
+ ((currentTick - nextTick) / task.period + 1) * task.period;
}
- newAgenda.push(event);
+ agenda.emplace(id, nextTick);
}
- agenda = std::move(newAgenda);
}
void TaskScheduler::run()
@@ -304,16 +314,17 @@ void TaskScheduler::enqueue(Event event, int64_t startTick)
}
TaskScheduler::Task::Task()
- : function(nullptr), period(0), enabled(false), policy(Policy::SKIP),
- lastCall(-1), activationStats(), periodStats(), workloadStats(),
- missedEvents(0), failedEvents(0)
+ : function(nullptr), period(0), startTick(0), enabled(false),
+ policy(Policy::SKIP), lastCall(-1), activationStats(), periodStats(),
+ workloadStats(), missedEvents(0), failedEvents(0)
{
}
-TaskScheduler::Task::Task(function_t function, uint32_t period, Policy policy)
- : function(function), period(period), enabled(true), policy(policy),
- lastCall(-1), activationStats(), periodStats(), workloadStats(),
- missedEvents(0), failedEvents(0)
+TaskScheduler::Task::Task(function_t function, uint32_t period, Policy policy,
+ int64_t startTick)
+ : function(function), period(period), startTick(startTick), enabled(true),
+ policy(policy), lastCall(-1), activationStats(), periodStats(),
+ workloadStats(), missedEvents(0), failedEvents(0)
{
}
diff --git a/src/shared/scheduler/TaskScheduler.h b/src/shared/scheduler/TaskScheduler.h
index b7e83e496..fb10dcf87 100644
--- a/src/shared/scheduler/TaskScheduler.h
+++ b/src/shared/scheduler/TaskScheduler.h
@@ -87,7 +87,7 @@ public:
* respected and the task will run consecutively for some time (See issue
* #91).
*/
- enum class Policy
+ enum class Policy : uint8_t
{
ONE_SHOT, ///< Run the task one single timer.
SKIP, // Skips lost executions and stays aligned with the original
@@ -133,17 +133,13 @@ public:
std::vector<TaskStatsResult> getTaskStats();
private:
- /**
- * @brief Check the start time of the tasks in the agenda and moves them in
- * the future respecting the period in respect to the original start time.
- */
- void normalizeTasks();
-
struct Task
{
function_t function;
- uint32_t period; // [ms]
- bool enabled; ///< Whether the task should be executed.
+ uint32_t period; // [ms]
+ int64_t startTick; ///< First activation time, useful for synchronizing
+ ///< tasks.
+ bool enabled; ///< Whether the task should be executed.
Policy policy;
int64_t lastCall; ///< Last activation tick for statistics computation.
Stats activationStats; ///< Stats about activation tick error.
@@ -163,8 +159,10 @@ private:
* @param function The std::function to be called
* @param period The Period in [ms]
* @param policy The task policy in case of a miss
+ * @param startTick The first activation time
*/
- explicit Task(function_t function, uint32_t period, Policy policy);
+ explicit Task(function_t function, uint32_t period, Policy policy,
+ int64_t startTick);
// Delete copy constructor and copy assignment operator to avoid copying
// and force moving
@@ -209,6 +207,21 @@ private:
using EventQueue =
std::priority_queue<Event, std::vector<Event>, std::greater<Event>>;
+ /**
+ * @brief Instantiates a new EventQueue backed by a vector with a
+ * capacity of `MAX_TASKS` to avoid reallocations when inserting new events.
+ */
+ static EventQueue makeAgenda();
+
+ /**
+ * @brief Populates the agenda prior to starting the scheduler. Checks the
+ * start time of the tasks in the agenda and moves them in the future
+ * respecting the period in respect to the original start time.
+ * @note This function must be called before starting the scheduler or the
+ * agenda will be empty.
+ */
+ void populateAgenda();
+
void run() override;
/**
--
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