Implement teardown lifecycle contract for ESPCpuMonitor

README.md

@@ -71,6 +71,7 @@ void loop() {
 
 When you set `sampleIntervalMs` to `0`, call `sampleNow()` on your monitor instance (for example, `cpuMonitor.sampleNow(sample)`) from your scheduler to drive sampling manually.
 If temperature is enabled, `getLastTemperature(current, average)` returns the latest reading and running mean (returns `false` when unsupported or not ready).
+When your feature shuts down (task exit, OTA handoff, mode switch), call `cpuMonitor.deinit()` to release idle hooks and timer resources.
 
 ## Gotchas
 - CPU usage numbers are floats in percent so you can see tiny changes; `1.0` means ~1% busy, not 100%. Feel free to round (`%.0f%%`) in your logs/UI if you prefer whole numbers.
@@ -82,7 +83,8 @@ If temperature is enabled, `getLastTemperature(current, average)` returns the la
 - Some ESP32 variants or Arduino builds omit the internal temperature sensor; in that case `temperatureC`/`temperatureAvgC` stay `NaN` and `getLastTemperature` returns `false`.
 
 ## API Reference
-- `bool init(const CpuMonitorConfig &cfg = {})` / `void deinit()` – register idle hooks, create the esp_timer (when `sampleIntervalMs > 0`), and reset state.
+- `bool init(const CpuMonitorConfig &cfg = {})` / `void deinit()` – register idle hooks, create the esp_timer (when `sampleIntervalMs > 0`), and reset state. `deinit()` is safe to call before `init()` and on repeated calls.
+- `bool isInitialized() const` – returns `true` while the monitor owns the shared idle hooks/timer resources.
 - `bool isReady() const` – returns true once calibration completed and a sample is stored.
 - `bool getLastSample(CpuUsageSample &out) const` / `float getLastAverage() const` / `float getLastSmoothedAverage() const` – read the latest sample; average/smoothed values return `-1.0f` until ready (or when smoothing is disabled).
 - `bool getLastTemperature(float &currentC, float &averageC) const` – latest temperature and running average; returns `false` if disabled, unsupported, or not yet sampled.

platformio.ini

@@ -0,0 +1,6 @@
+[env:esp32dev]
+platform = espressif32
+board = esp32dev
+framework = arduino
+monitor_speed = 115200
+build_flags = -std=gnu++17

src/esp_cpu_monitor/cpu_monitor.cpp

@@ -209,6 +209,9 @@ void ESPCpuMonitor::deinit() {
     calibrated_ = false;
     hasSample_ = false;
     history_.clear();
+    callbacks_.clear();
+    resetSmoothingState();
+    resetTemperatureState();
 }
 
 bool ESPCpuMonitor::isReady() const {
@@ -268,7 +271,7 @@ std::vector<CpuUsageSample> ESPCpuMonitor::history() const {
 }
 
 bool ESPCpuMonitor::sampleNow(CpuUsageSample &out) {
-    if (s_instance != this) {
+    if (!isInitialized()) {
         ESP_LOGE(TAG, "Call init() before sampleNow()");
         return false;
     }
@@ -306,7 +309,7 @@ bool IRAM_ATTR ESPCpuMonitor::idleHookCore1() {
 
 void ESPCpuMonitor::timerCallback(void *arg) {
     auto *self = static_cast<ESPCpuMonitor *>(arg);
-    if (!self) {
+    if (!self || !self->isInitialized()) {
         return;
     }
     CpuUsageSample sample{};

src/esp_cpu_monitor/cpu_monitor.h

@@ -124,6 +124,7 @@ class ESPCpuMonitor {
 
     bool init(const CpuMonitorConfig &cfg = {});
     void deinit();
+    bool isInitialized() const { return s_instance == this; }
 
     bool isReady() const;
     bool getLastSample(CpuUsageSample &out) const;

test/CMakeLists.txt

@@ -0,0 +1,4 @@
+# Host-side tests are not available because ESPCpuMonitor depends on
+# ESP32 FreeRTOS idle hooks and esp_timer. Run on-device tests in
+# test/test_cpu_monitor with PlatformIO/Arduino.
+message(STATUS "ESPCpuMonitor: host tests are disabled.")

test/test_cpu_monitor/test_cpu_monitor.cpp

@@ -0,0 +1,81 @@
+#include <Arduino.h>
+#include <ESPCpuMonitor.h>
+#include <unity.h>
+
+namespace {
+
+CpuMonitorConfig testConfig() {
+    CpuMonitorConfig cfg{};
+    cfg.sampleIntervalMs = 0;
+    cfg.calibrationSamples = 1;
+    cfg.historySize = 4;
+    cfg.enablePerCore = true;
+    cfg.enableTemperature = false;
+    cfg.smoothingMode = CpuSmoothingMode::None;
+    return cfg;
+}
+
+void test_deinit_is_safe_before_init() {
+    ESPCpuMonitor monitor;
+    TEST_ASSERT_FALSE(monitor.isInitialized());
+
+    monitor.deinit();
+    TEST_ASSERT_FALSE(monitor.isInitialized());
+}
+
+void test_deinit_is_idempotent() {
+    ESPCpuMonitor monitor;
+    TEST_ASSERT_TRUE(monitor.init(testConfig()));
+    TEST_ASSERT_TRUE(monitor.isInitialized());
+
+    monitor.deinit();
+    TEST_ASSERT_FALSE(monitor.isInitialized());
+
+    monitor.deinit();
+    TEST_ASSERT_FALSE(monitor.isInitialized());
+}
+
+void test_reinit_after_deinit() {
+    ESPCpuMonitor monitor;
+    TEST_ASSERT_TRUE(monitor.init(testConfig()));
+    TEST_ASSERT_TRUE(monitor.isInitialized());
+
+    monitor.deinit();
+    TEST_ASSERT_FALSE(monitor.isInitialized());
+
+    TEST_ASSERT_TRUE(monitor.init(testConfig()));
+    TEST_ASSERT_TRUE(monitor.isInitialized());
+    monitor.deinit();
+}
+
+void test_destructor_deinits_active_instance() {
+    {
+        ESPCpuMonitor first;
+        TEST_ASSERT_TRUE(first.init(testConfig()));
+        TEST_ASSERT_TRUE(first.isInitialized());
+    }
+
+    ESPCpuMonitor second;
+    TEST_ASSERT_TRUE(second.init(testConfig()));
+    TEST_ASSERT_TRUE(second.isInitialized());
+    second.deinit();
+}
+
+}  // namespace
+
+void setUp() {}
+void tearDown() {}
+
+void setup() {
+    delay(2000);
+    UNITY_BEGIN();
+    RUN_TEST(test_deinit_is_safe_before_init);
+    RUN_TEST(test_deinit_is_idempotent);
+    RUN_TEST(test_reinit_after_deinit);
+    RUN_TEST(test_destructor_deinits_active_instance);
+    UNITY_END();
+}
+
+void loop() {
+    delay(1000);
+}