[FL-3846] Event Loop Timers (#3721)

* Implement POC event loop tmers (not all edge cases are handled)
* Use a separate ready list to allow for (re)starting and stopping of timers from callback
* Improve the test application
* Improve timer API and test application
* Improve timeout calculation logic
* Improve timer API, update documentation
* Fix API usage error
* Update doxygen comments
* Revert the old (correct) check
* Improve function naming
* Check whether a timer was on the expired list before processing it
* Implement tick callback
* Add critical sections to improve timer consistency
* Simplify event loop timer API
* Remove redundant search
* Refactor timer logic, use message queue
* Simplify FuriEventLoopTimer API
* Improve event loop timer logic
* Update the f18 target
* Remove superfluous clears
* Correct f18 api symbols
* Fix doxygen comments
* Update .pvsconfig
* Use a double push list instead of deque
* Update .pvsconfig
* Add pending callback functionality
* Restore unprocessed flags when applicable
* Refactor Dolphin app to use FuriEventLoop
* Improve naming
* Update naming some more
* Fix a typo Co-authored-by: Silent <CookiePLMonster@users.noreply.github.com>
* Fix wait time in example
* Bump API version
* Debug: multiple of 25 timings in event loop blink test
* Separate FuriEventLoopTimer to its own set of files
* Improve start time calculation for periodic timers
* Do not use dynamic allocations for timer requests
* Split the tick functionality in separate files, rearrange code
* Improve timer queue handling
* Properly reset GPIO pins in the test app
* Properly initialise GPIO pins in the test app too
* Furi: variable naming in event loop
* Furi: fix spelling in event loop

Co-authored-by: あく <alleteam@gmail.com>
Co-authored-by: Silent <CookiePLMonster@users.noreply.github.com>

.pvsconfig

@@ -3,10 +3,12 @@
 //-V:M_EACH:1048,1044
 //-V:ARRAY_DEF:760,747,568,776,729,712,654,1103
 //-V:LIST_DEF:760,747,568,712,729,654,776,1103
+//-V:LIST_DUAL_PUSH_DEF:524,760,774
 //-V:BPTREE_DEF2:779,1086,557,773,512
 //-V:DICT_DEF2:779,524,776,760,1044,1001,729,590,568,747,685,1103
 //-V:ALGO_DEF:1048,747,1044
 //-V:TUPLE_DEF2:524,590,1001,760
+//-V:DEQUE_DEF:658,747,760
 
 # Non-severe malloc/null pointer deref warnings
 //-V::522:2,3

applications/debug/event_loop_blink_test/application.fam

@@ -0,0 +1,10 @@
+App(
+    appid="event_loop_blink_test",
+    name="Event Loop Blink Test",
+    apptype=FlipperAppType.DEBUG,
+    entry_point="event_loop_blink_test_app",
+    requires=["input"],
+    stack_size=1 * 1024,
+    order=20,
+    fap_category="Debug",
+)

applications/debug/event_loop_blink_test/event_loop_blink_test.c

@@ -0,0 +1,169 @@
+#include <furi.h>
+#include <furi_hal_resources.h>
+
+#include <gui/gui.h>
+#include <gui/elements.h>
+#include <gui/view_port.h>
+
+#include <input/input.h>
+
+#define TAG "EventLoopBlinkTest"
+
+#define TIMER_COUNT (6U)
+
+typedef struct {
+    FuriEventLoop* event_loop;
+    FuriMessageQueue* input_queue;
+    FuriEventLoopTimer* timers[TIMER_COUNT];
+} EventLoopBlinkTestApp;
+
+static const GpioPin* blink_gpio_pins[] = {
+    &gpio_ext_pa7,
+    &gpio_ext_pa6,
+    &gpio_ext_pa4,
+    &gpio_ext_pb3,
+    &gpio_ext_pb2,
+    &gpio_ext_pc3,
+};
+
+static_assert(COUNT_OF(blink_gpio_pins) == TIMER_COUNT);
+
+static const uint32_t timer_intervals[] = {
+    25,
+    50,
+    100,
+    200,
+    400,
+    800,
+};
+
+static_assert(COUNT_OF(timer_intervals) == TIMER_COUNT);
+
+static void blink_gpio_init(void) {
+    for(size_t i = 0; i < TIMER_COUNT; ++i) {
+        furi_hal_gpio_init_simple(blink_gpio_pins[i], GpioModeOutputPushPull);
+        furi_hal_gpio_write(blink_gpio_pins[i], false);
+    }
+
+    furi_hal_gpio_init_simple(&gpio_ext_pc0, GpioModeOutputPushPull);
+    furi_hal_gpio_write(&gpio_ext_pc0, false);
+}
+
+static void blink_gpio_deinit(void) {
+    for(size_t i = 0; i < TIMER_COUNT; ++i) {
+        furi_hal_gpio_write(blink_gpio_pins[i], false);
+        furi_hal_gpio_init_simple(blink_gpio_pins[i], GpioModeAnalog);
+    }
+
+    furi_hal_gpio_write(&gpio_ext_pc0, false);
+    furi_hal_gpio_init_simple(&gpio_ext_pc0, GpioModeAnalog);
+}
+
+static void view_port_draw_callback(Canvas* canvas, void* context) {
+    UNUSED(context);
+    canvas_clear(canvas);
+    elements_text_box(
+        canvas,
+        0,
+        0,
+        canvas_width(canvas),
+        canvas_height(canvas),
+        AlignCenter,
+        AlignCenter,
+        "\e#Event Loop Timers Test\e#\n"
+        "Press buttons\n"
+        "to enable or disable timers\n"
+        "\e#Exit\e# = long press \e#Back\e#",
+        false);
+}
+
+static void view_port_input_callback(InputEvent* input_event, void* context) {
+    EventLoopBlinkTestApp* app = context;
+    furi_message_queue_put(app->input_queue, input_event, 0);
+}
+
+static bool input_queue_callback(FuriMessageQueue* queue, void* context) {
+    EventLoopBlinkTestApp* app = context;
+
+    InputEvent event;
+    FuriStatus status = furi_message_queue_get(queue, &event, 0);
+    furi_assert(status == FuriStatusOk);
+
+    if(event.type == InputTypeShort) {
+        const size_t timer_idx = event.key;
+        furi_assert(timer_idx < TIMER_COUNT);
+
+        FuriEventLoopTimer* timer = app->timers[timer_idx];
+
+        if(furi_event_loop_timer_is_running(timer)) {
+            furi_event_loop_timer_stop(timer);
+        } else {
+            furi_event_loop_timer_restart(timer);
+        }
+
+    } else if(event.type == InputTypeLong) {
+        if(event.key == InputKeyBack) {
+            furi_event_loop_stop(app->event_loop);
+        }
+    }
+
+    return true;
+}
+
+static void blink_timer_callback(void* context) {
+    const GpioPin* gpio = blink_gpio_pins[(size_t)context];
+    furi_hal_gpio_write(gpio, !furi_hal_gpio_read(gpio));
+}
+
+static void event_loop_tick_callback(void* context) {
+    UNUSED(context);
+    furi_hal_gpio_write(&gpio_ext_pc0, !furi_hal_gpio_read(&gpio_ext_pc0));
+}
+
+int32_t event_loop_blink_test_app(void* arg) {
+    UNUSED(arg);
+
+    blink_gpio_init();
+
+    EventLoopBlinkTestApp app;
+
+    app.event_loop = furi_event_loop_alloc();
+    app.input_queue = furi_message_queue_alloc(3, sizeof(InputEvent));
+
+    for(size_t i = 0; i < TIMER_COUNT; ++i) {
+        app.timers[i] = furi_event_loop_timer_alloc(
+            app.event_loop, blink_timer_callback, FuriEventLoopTimerTypePeriodic, (void*)i);
+        furi_event_loop_timer_start(app.timers[i], timer_intervals[i]);
+    }
+
+    ViewPort* view_port = view_port_alloc();
+    view_port_draw_callback_set(view_port, view_port_draw_callback, &app);
+    view_port_input_callback_set(view_port, view_port_input_callback, &app);
+
+    Gui* gui = furi_record_open(RECORD_GUI);
+    gui_add_view_port(gui, view_port, GuiLayerFullscreen);
+
+    furi_event_loop_tick_set(app.event_loop, 500, event_loop_tick_callback, &app);
+    furi_event_loop_message_queue_subscribe(
+        app.event_loop, app.input_queue, FuriEventLoopEventIn, input_queue_callback, &app);
+
+    furi_event_loop_run(app.event_loop);
+
+    gui_remove_view_port(gui, view_port);
+    view_port_free(view_port);
+
+    furi_record_close(RECORD_GUI);
+
+    furi_event_loop_message_queue_unsubscribe(app.event_loop, app.input_queue);
+    furi_message_queue_free(app.input_queue);
+
+    for(size_t i = 0; i < TIMER_COUNT; ++i) {
+        furi_event_loop_timer_free(app.timers[i]);
+    }
+
+    furi_event_loop_free(app.event_loop);
+
+    blink_gpio_deinit();
+
+    return 0;
+}

applications/services/dolphin/dolphin.c

@@ -1,22 +1,48 @@
-#include "dolphin.h"
-#include "helpers/dolphin_state.h"
 #include "dolphin_i.h"
+
 #include <furi_hal.h>
-#include <stdint.h>
-#include <furi.h>
-#define DOLPHIN_LOCK_EVENT_FLAG (0x1)
 
 #define TAG "Dolphin"
-#define HOURS_IN_TICKS(x) ((x) * 60 * 60 * 1000)
 
-static void dolphin_update_clear_limits_timer_period(Dolphin* dolphin);
+#define DOLPHIN_LOCK_EVENT_FLAG (0x1)
+#define EVENT_QUEUE_SIZE (8)
+
+#define SECONDS_IN_TICKS(x) ((x) * 1000UL)
+#define MINUTES_IN_TICKS(x) (SECONDS_IN_TICKS(x) * 60UL)
+#define HOURS_IN_TICKS(x) (MINUTES_IN_TICKS(x) * 60UL)
+#define DATE_IN_TICKS(h, m, s) (HOURS_IN_TICKS(h) + MINUTES_IN_TICKS(m) + SECONDS_IN_TICKS(s))
+
+#define FLUSH_TIMEOUT_TICKS (SECONDS_IN_TICKS(30UL))
+
+#ifndef DOLPHIN_DEBUG
+#define BUTTHURT_INCREASE_PERIOD_TICKS (HOURS_IN_TICKS(48UL))
+#define CLEAR_LIMITS_PERIOD_TICKS (HOURS_IN_TICKS(24UL))
+#define CLEAR_LIMITS_UPDATE_PERIOD_TICKS (HOURS_IN_TICKS(1UL))
+#else
+#define BUTTHURT_INCREASE_PERIOD_TICKS (SECONDS_IN_TICKS(30UL))
+#define CLEAR_LIMITS_PERIOD_TICKS (MINUTES_IN_TICKS(1))
+#define CLEAR_LIMITS_UPDATE_PERIOD_TICKS (SECONDS_IN_TICKS(5UL))
+#endif
+
+#define CLEAR_LIMITS_UPDATE_THRESHOLD_TICKS (MINUTES_IN_TICKS(5UL))
+
+#define CLEAR_LIMITS_TIME_HOURS (5UL)
+#define CLEAR_LIMITS_TIME_TICKS (HOURS_IN_TICKS(CLEAR_LIMITS_TIME_HOURS))
+
+static void dolphin_event_send_async(Dolphin* dolphin, DolphinEvent* event);
+static void dolphin_event_send_wait(Dolphin* dolphin, DolphinEvent* event);
+
+// Public API
 
 void dolphin_deed(DolphinDeed deed) {
-    Dolphin* dolphin = (Dolphin*)furi_record_open(RECORD_DOLPHIN);
+    Dolphin* dolphin = furi_record_open(RECORD_DOLPHIN);
+
     DolphinEvent event;
     event.type = DolphinEventTypeDeed;
     event.deed = deed;
+
     dolphin_event_send_async(dolphin, &event);
+
     furi_record_close(RECORD_DOLPHIN);
 }
 
@@ -43,52 +69,75 @@ void dolphin_flush(Dolphin* dolphin) {
     dolphin_event_send_wait(dolphin, &event);
 }
 
-void dolphin_butthurt_timer_callback(void* context) {
-    Dolphin* dolphin = context;
-    furi_assert(dolphin);
+void dolphin_upgrade_level(Dolphin* dolphin) {
+    furi_check(dolphin);
 
     DolphinEvent event;
-    event.type = DolphinEventTypeIncreaseButthurt;
+    event.type = DolphinEventTypeLevel;
+
     dolphin_event_send_async(dolphin, &event);
 }
 
-void dolphin_flush_timer_callback(void* context) {
+FuriPubSub* dolphin_get_pubsub(Dolphin* dolphin) {
+    furi_check(dolphin);
+    return dolphin->pubsub;
+}
+
+// Private functions
+
+static void dolphin_butthurt_timer_callback(void* context) {
     Dolphin* dolphin = context;
     furi_assert(dolphin);
 
-    DolphinEvent event;
-    event.type = DolphinEventTypeFlush;
-    dolphin_event_send_async(dolphin, &event);
+    FURI_LOG_I(TAG, "Increase butthurt");
+    dolphin_state_butthurted(dolphin->state);
+    dolphin_state_save(dolphin->state);
 }
 
-void dolphin_clear_limits_timer_callback(void* context) {
+static void dolphin_flush_timer_callback(void* context) {
     Dolphin* dolphin = context;
     furi_assert(dolphin);
 
-    furi_timer_start(dolphin->clear_limits_timer, HOURS_IN_TICKS(24));
-
-    DolphinEvent event;
-    event.type = DolphinEventTypeClearLimits;
-    dolphin_event_send_async(dolphin, &event);
+    FURI_LOG_I(TAG, "Flush stats");
+    dolphin_state_save(dolphin->state);
 }
 
-Dolphin* dolphin_alloc(void) {
+static void dolphin_clear_limits_timer_callback(void* context) {
+    Dolphin* dolphin = context;
+    furi_assert(dolphin);
+
+    FURI_LOG_I(TAG, "Clear limits");
+    dolphin_state_clear_limits(dolphin->state);
+    dolphin_state_save(dolphin->state);
+}
+
+static Dolphin* dolphin_alloc(void) {
     Dolphin* dolphin = malloc(sizeof(Dolphin));
 
     dolphin->state = dolphin_state_alloc();
-    dolphin->event_queue = furi_message_queue_alloc(8, sizeof(DolphinEvent));
     dolphin->pubsub = furi_pubsub_alloc();
-    dolphin->butthurt_timer =
-        furi_timer_alloc(dolphin_butthurt_timer_callback, FuriTimerTypePeriodic, dolphin);
-    dolphin->flush_timer =
-        furi_timer_alloc(dolphin_flush_timer_callback, FuriTimerTypeOnce, dolphin);
-    dolphin->clear_limits_timer =
-        furi_timer_alloc(dolphin_clear_limits_timer_callback, FuriTimerTypePeriodic, dolphin);
+    dolphin->event_queue = furi_message_queue_alloc(EVENT_QUEUE_SIZE, sizeof(DolphinEvent));
+    dolphin->event_loop = furi_event_loop_alloc();
+
+    dolphin->butthurt_timer = furi_event_loop_timer_alloc(
+        dolphin->event_loop,
+        dolphin_butthurt_timer_callback,
+        FuriEventLoopTimerTypePeriodic,
+        dolphin);
+
+    dolphin->flush_timer = furi_event_loop_timer_alloc(
+        dolphin->event_loop, dolphin_flush_timer_callback, FuriEventLoopTimerTypeOnce, dolphin);
+
+    dolphin->clear_limits_timer = furi_event_loop_timer_alloc(
+        dolphin->event_loop,
+        dolphin_clear_limits_timer_callback,
+        FuriEventLoopTimerTypePeriodic,
+        dolphin);
 
     return dolphin;
 }
 
-void dolphin_event_send_async(Dolphin* dolphin, DolphinEvent* event) {
+static void dolphin_event_send_async(Dolphin* dolphin, DolphinEvent* event) {
     furi_assert(dolphin);
     furi_assert(event);
     event->flag = NULL;
@@ -96,7 +145,7 @@ void dolphin_event_send_async(Dolphin* dolphin, DolphinEvent* event) {
         furi_message_queue_put(dolphin->event_queue, event, FuriWaitForever) == FuriStatusOk);
 }
 
-void dolphin_event_send_wait(Dolphin* dolphin, DolphinEvent* event) {
+static void dolphin_event_send_wait(Dolphin* dolphin, DolphinEvent* event) {
     furi_assert(dolphin);
     furi_assert(event);
 
@@ -110,39 +159,81 @@ void dolphin_event_send_wait(Dolphin* dolphin, DolphinEvent* event) {
     furi_event_flag_free(event->flag);
 }
 
-void dolphin_event_release(Dolphin* dolphin, DolphinEvent* event) {
-    UNUSED(dolphin);
+static void dolphin_event_release(DolphinEvent* event) {
     if(event->flag) {
         furi_event_flag_set(event->flag, DOLPHIN_LOCK_EVENT_FLAG);
     }
 }
 
-FuriPubSub* dolphin_get_pubsub(Dolphin* dolphin) {
-    furi_check(dolphin);
-    return dolphin->pubsub;
-}
+static void dolphin_update_clear_limits_timer_period(void* context) {
+    furi_assert(context);
+    Dolphin* dolphin = context;
 
-static void dolphin_update_clear_limits_timer_period(Dolphin* dolphin) {
-    furi_assert(dolphin);
-    uint32_t now_ticks = furi_get_tick();
-    uint32_t timer_expires_at = furi_timer_get_expire_time(dolphin->clear_limits_timer);
+    uint32_t time_to_clear_limits =
+        furi_event_loop_timer_get_remaining_time(dolphin->clear_limits_timer);
 
-    if((timer_expires_at - now_ticks) > HOURS_IN_TICKS(0.1)) {
+    if(time_to_clear_limits > CLEAR_LIMITS_UPDATE_THRESHOLD_TICKS) {
         DateTime date;
         furi_hal_rtc_get_datetime(&date);
-        uint32_t now_time_in_ms = ((date.hour * 60 + date.minute) * 60 + date.second) * 1000;
-        uint32_t time_to_clear_limits = 0;
 
-        if(date.hour < 5) {
-            time_to_clear_limits = HOURS_IN_TICKS(5) - now_time_in_ms;
+        const uint32_t now_time_ticks = DATE_IN_TICKS(date.hour, date.minute, date.second);
+
+        if(date.hour < CLEAR_LIMITS_TIME_HOURS) {
+            time_to_clear_limits = CLEAR_LIMITS_TIME_TICKS - now_time_ticks;
         } else {
-            time_to_clear_limits = HOURS_IN_TICKS(24 + 5) - now_time_in_ms;
+            time_to_clear_limits =
+                CLEAR_LIMITS_PERIOD_TICKS + CLEAR_LIMITS_TIME_TICKS - now_time_ticks;
         }
 
-        furi_timer_start(dolphin->clear_limits_timer, time_to_clear_limits);
+        furi_event_loop_timer_start(dolphin->clear_limits_timer, time_to_clear_limits);
     }
+
+    FURI_LOG_D(TAG, "Daily limits reset in %lu ms", time_to_clear_limits);
 }
 
+static bool dolphin_process_event(FuriMessageQueue* queue, void* context) {
+    UNUSED(queue);
+
+    Dolphin* dolphin = context;
+    DolphinEvent event;
+
+    FuriStatus status = furi_message_queue_get(dolphin->event_queue, &event, 0);
+    furi_check(status == FuriStatusOk);
+
+    if(event.type == DolphinEventTypeDeed) {
+        dolphin_state_on_deed(dolphin->state, event.deed);
+
+        DolphinPubsubEvent event = DolphinPubsubEventUpdate;
+        furi_pubsub_publish(dolphin->pubsub, &event);
+        furi_event_loop_timer_start(dolphin->butthurt_timer, BUTTHURT_INCREASE_PERIOD_TICKS);
+        furi_event_loop_timer_start(dolphin->flush_timer, FLUSH_TIMEOUT_TICKS);
+
+    } else if(event.type == DolphinEventTypeStats) {
+        event.stats->icounter = dolphin->state->data.icounter;
+        event.stats->butthurt = dolphin->state->data.butthurt;
+        event.stats->timestamp = dolphin->state->data.timestamp;
+        event.stats->level = dolphin_get_level(dolphin->state->data.icounter);
+        event.stats->level_up_is_pending =
+            !dolphin_state_xp_to_levelup(dolphin->state->data.icounter);
+
+    } else if(event.type == DolphinEventTypeFlush) {
+        furi_event_loop_timer_start(dolphin->flush_timer, FLUSH_TIMEOUT_TICKS);
+
+    } else if(event.type == DolphinEventTypeLevel) {
+        dolphin_state_increase_level(dolphin->state);
+        furi_event_loop_timer_start(dolphin->flush_timer, FLUSH_TIMEOUT_TICKS);
+
+    } else {
+        furi_crash();
+    }
+
+    dolphin_event_release(&event);
+
+    return true;
+}
+
+// Application thread
+
 int32_t dolphin_srv(void* p) {
     UNUSED(p);
 
@@ -157,54 +248,27 @@ int32_t dolphin_srv(void* p) {
     furi_record_create(RECORD_DOLPHIN, dolphin);
 
     dolphin_state_load(dolphin->state);
-    furi_timer_restart(dolphin->butthurt_timer, HOURS_IN_TICKS(2 * 24));
-    dolphin_update_clear_limits_timer_period(dolphin);
-    furi_timer_restart(dolphin->clear_limits_timer, HOURS_IN_TICKS(24));
 
-    DolphinEvent event;
-    while(1) {
-        if(furi_message_queue_get(dolphin->event_queue, &event, HOURS_IN_TICKS(1)) ==
-           FuriStatusOk) {
-            if(event.type == DolphinEventTypeDeed) {
-                dolphin_state_on_deed(dolphin->state, event.deed);
-                DolphinPubsubEvent event = DolphinPubsubEventUpdate;
-                furi_pubsub_publish(dolphin->pubsub, &event);
-                furi_timer_restart(dolphin->butthurt_timer, HOURS_IN_TICKS(2 * 24));
-                furi_timer_restart(dolphin->flush_timer, 30 * 1000);
-            } else if(event.type == DolphinEventTypeStats) {
-                event.stats->icounter = dolphin->state->data.icounter;
-                event.stats->butthurt = dolphin->state->data.butthurt;
-                event.stats->timestamp = dolphin->state->data.timestamp;
-                event.stats->level = dolphin_get_level(dolphin->state->data.icounter);
-                event.stats->level_up_is_pending =
-                    !dolphin_state_xp_to_levelup(dolphin->state->data.icounter);
-            } else if(event.type == DolphinEventTypeFlush) {
-                FURI_LOG_I(TAG, "Flush stats");
-                dolphin_state_save(dolphin->state);
-            } else if(event.type == DolphinEventTypeClearLimits) {
-                FURI_LOG_I(TAG, "Clear limits");
-                dolphin_state_clear_limits(dolphin->state);
-                dolphin_state_save(dolphin->state);
-            } else if(event.type == DolphinEventTypeIncreaseButthurt) {
-                FURI_LOG_I(TAG, "Increase butthurt");
-                dolphin_state_butthurted(dolphin->state);
-                dolphin_state_save(dolphin->state);
-            }
-            dolphin_event_release(dolphin, &event);
-        } else {
-            /* once per hour check rtc time is not changed */
-            dolphin_update_clear_limits_timer_period(dolphin);
-        }
-    }
+    furi_event_loop_message_queue_subscribe(
+        dolphin->event_loop,
+        dolphin->event_queue,
+        FuriEventLoopEventIn,
+        dolphin_process_event,
+        dolphin);
 
-    furi_crash("That was unexpected");
+    furi_event_loop_timer_start(dolphin->butthurt_timer, BUTTHURT_INCREASE_PERIOD_TICKS);
+    furi_event_loop_timer_start(dolphin->clear_limits_timer, CLEAR_LIMITS_PERIOD_TICKS);
+
+    furi_event_loop_tick_set(
+        dolphin->event_loop,
+        CLEAR_LIMITS_UPDATE_PERIOD_TICKS,
+        dolphin_update_clear_limits_timer_period,
+        dolphin);
+
+    furi_event_loop_pend_callback(
+        dolphin->event_loop, dolphin_update_clear_limits_timer_period, dolphin);
+
+    furi_event_loop_run(dolphin->event_loop);
 
     return 0;
 }
-
-void dolphin_upgrade_level(Dolphin* dolphin) {
-    furi_check(dolphin);
-
-    dolphin_state_increase_level(dolphin->state);
-    dolphin_flush(dolphin);
-}

applications/services/dolphin/dolphin.h

@@ -1,10 +1,9 @@
 #pragma once
 
-#include "helpers/dolphin_deed.h"
-
-#include <gui/view.h>
-#include <core/pubsub.h>
 #include <stdbool.h>
+#include <core/pubsub.h>
+
+#include "helpers/dolphin_deed.h"
 
 #ifdef __cplusplus
 extern "C" {

applications/services/dolphin/dolphin_i.h

@@ -1,8 +1,8 @@
 #pragma once
 
-#include <core/pubsub.h>
 #include <furi.h>
-#include <furi_hal.h>
+
+#include <core/pubsub.h>
 
 #include "dolphin.h"
 #include "helpers/dolphin_state.h"
@@ -11,8 +11,7 @@ typedef enum {
     DolphinEventTypeDeed,
     DolphinEventTypeStats,
     DolphinEventTypeFlush,
-    DolphinEventTypeIncreaseButthurt,
-    DolphinEventTypeClearLimits,
+    DolphinEventTypeLevel,
 } DolphinEventType;
 
 typedef struct {
@@ -25,20 +24,11 @@ typedef struct {
 } DolphinEvent;
 
 struct Dolphin {
-    // State
     DolphinState* state;
-    // Queue
-    FuriMessageQueue* event_queue;
     FuriPubSub* pubsub;
-    FuriTimer* butthurt_timer;
-    FuriTimer* flush_timer;
-    FuriTimer* clear_limits_timer;
+    FuriMessageQueue* event_queue;
+    FuriEventLoop* event_loop;
+    FuriEventLoopTimer* butthurt_timer;
+    FuriEventLoopTimer* flush_timer;
+    FuriEventLoopTimer* clear_limits_timer;
 };
-
-Dolphin* dolphin_alloc(void);
-
-void dolphin_event_send_async(Dolphin* dolphin, DolphinEvent* event);
-
-void dolphin_event_send_wait(Dolphin* dolphin, DolphinEvent* event);
-
-void dolphin_event_release(Dolphin* dolphin, DolphinEvent* event);

furi/core/event_loop.c

@@ -5,32 +5,14 @@
 #include "check.h"
 #include "thread.h"
 
-#include <m-bptree.h>
-#include <m-i-list.h>
-
 #include <FreeRTOS.h>
 #include <task.h>
 
 #define TAG "FuriEventLoop"
 
-struct FuriEventLoopItem {
-    // Source
-    FuriEventLoop* owner;
-
-    // Tracking item
-    const FuriEventLoopContract* contract;
-    void* object;
-    FuriEventLoopEvent event;
-
-    // Callback and context
-    FuriEventLoopMessageQueueCallback callback;
-    void* callback_context;
-
-    // Waiting list
-    ILIST_INTERFACE(WaitingList, struct FuriEventLoopItem);
-};
-
-ILIST_DEF(WaitingList, FuriEventLoopItem, M_POD_OPLIST)
+/*
+ * Private functions
+ */
 
 static FuriEventLoopItem* furi_event_loop_item_alloc(
     FuriEventLoop* owner,
@@ -47,56 +29,17 @@ static void furi_event_loop_item_set_callback(
 
 static void furi_event_loop_item_notify(FuriEventLoopItem* instance);
 
-/* Event Loop RB tree */
-#define FURI_EVENT_LOOP_TREE_RANK (4)
+static void furi_event_loop_process_pending_callbacks(FuriEventLoop* instance) {
+    for(; !PendingQueue_empty_p(instance->pending_queue);
+        PendingQueue_pop_back(NULL, instance->pending_queue)) {
+        const FuriEventLoopPendingQueueItem* item = PendingQueue_back(instance->pending_queue);
+        item->callback(item->context);
+    }
+}
 
-BPTREE_DEF2( // NOLINT
-    FuriEventLoopTree,
-    FURI_EVENT_LOOP_TREE_RANK,
-    void*, /* pointer to object we track */
-    M_PTR_OPLIST,
-    FuriEventLoopItem*, /* pointer to the FuriEventLoopItem */
-    M_PTR_OPLIST)
-
-#define M_OPL_FuriEventLoopTree_t() BPTREE_OPLIST(FuriEventLoopTree, M_POD_OPLIST)
-
-#define FURI_EVENT_LOOP_FLAG_NOTIFY_INDEX (2)
-
-typedef enum {
-    FuriEventLoopFlagEvent = (1 << 0),
-    FuriEventLoopFlagStop = (1 << 1),
-} FuriEventLoopFlag;
-
-#define FuriEventLoopFlagAll (FuriEventLoopFlagEvent | FuriEventLoopFlagStop)
-
-typedef enum {
-    FuriEventLoopProcessStatusComplete,
-    FuriEventLoopProcessStatusIncomplete,
-    FuriEventLoopProcessStatusAgain,
-} FuriEventLoopProcessStatus;
-
-typedef enum {
-    FuriEventLoopStateIdle,
-    FuriEventLoopStateProcessing,
-} FuriEventLoopState;
-
-struct FuriEventLoop {
-    // Only works if all operations are done from the same thread
-    FuriThreadId thread_id;
-
-    // Poller state
-    volatile FuriEventLoopState state;
-
-    // Tree
-    FuriEventLoopTree_t tree;
-    // Tree waiting list
-    WaitingList_t waiting_list;
-
-    // Tick event
-    uint32_t tick_interval;
-    FuriEventLoopTickCallback tick_callback;
-    void* tick_callback_context;
-};
+/*
+ * Main public API
+ */
 
 FuriEventLoop* furi_event_loop_alloc(void) {
     FuriEventLoop* instance = malloc(sizeof(FuriEventLoop));
@@ -105,6 +48,9 @@ FuriEventLoop* furi_event_loop_alloc(void) {
 
     FuriEventLoopTree_init(instance->tree);
     WaitingList_init(instance->waiting_list);
+    TimerList_init(instance->timer_list);
+    TimerQueue_init(instance->timer_queue);
+    PendingQueue_init(instance->pending_queue);
 
     // Clear notification state and value
     xTaskNotifyStateClearIndexed(instance->thread_id, FURI_EVENT_LOOP_FLAG_NOTIFY_INDEX);
@@ -117,14 +63,19 @@ FuriEventLoop* furi_event_loop_alloc(void) {
 void furi_event_loop_free(FuriEventLoop* instance) {
     furi_check(instance);
     furi_check(instance->thread_id == furi_thread_get_current_id());
+    furi_check(instance->state == FuriEventLoopStateStopped);
+
+    furi_event_loop_process_timer_queue(instance);
+    furi_check(TimerList_empty_p(instance->timer_list));
 
     FuriEventLoopTree_clear(instance->tree);
+    PendingQueue_clear(instance->pending_queue);
 
     uint32_t flags = 0;
     BaseType_t ret = xTaskNotifyWaitIndexed(
         FURI_EVENT_LOOP_FLAG_NOTIFY_INDEX, 0, FuriEventLoopFlagAll, &flags, 0);
     if(ret == pdTRUE) {
-        FURI_LOG_D(TAG, "Some events was not processed: 0x%lx", flags);
+        FURI_LOG_D(TAG, "Some events were not processed: 0x%lx", flags);
     }
 
     free(instance);
@@ -145,33 +96,51 @@ static FuriEventLoopProcessStatus
     }
 }
 
+static void furi_event_loop_restore_flags(FuriEventLoop* instance, uint32_t flags) {
+    if(flags) {
+        xTaskNotifyIndexed(
+            instance->thread_id, FURI_EVENT_LOOP_FLAG_NOTIFY_INDEX, flags, eSetBits);
+    }
+}
+
 void furi_event_loop_run(FuriEventLoop* instance) {
     furi_check(instance);
     furi_check(instance->thread_id == furi_thread_get_current_id());
 
+    furi_event_loop_init_tick(instance);
+
     furi_thread_set_signal_callback(
         instance->thread_id, furi_event_loop_signal_callback, instance);
 
-    uint32_t timeout = instance->tick_callback ? instance->tick_interval : FuriWaitForever;
-
     while(true) {
+        instance->state = FuriEventLoopStateIdle;
+
+        const TickType_t ticks_to_sleep =
+            MIN(furi_event_loop_get_timer_wait_time(instance),
+                furi_event_loop_get_tick_wait_time(instance));
+
         uint32_t flags = 0;
         BaseType_t ret = xTaskNotifyWaitIndexed(
-            FURI_EVENT_LOOP_FLAG_NOTIFY_INDEX, 0, FuriEventLoopFlagAll, &flags, timeout);
+            FURI_EVENT_LOOP_FLAG_NOTIFY_INDEX, 0, FuriEventLoopFlagAll, &flags, ticks_to_sleep);
 
         instance->state = FuriEventLoopStateProcessing;
+
         if(ret == pdTRUE) {
             if(flags & FuriEventLoopFlagStop) {
-                instance->state = FuriEventLoopStateIdle;
+                instance->state = FuriEventLoopStateStopped;
                 break;
+
             } else if(flags & FuriEventLoopFlagEvent) {
                 FuriEventLoopItem* item = NULL;
                 FURI_CRITICAL_ENTER();
+
                 if(!WaitingList_empty_p(instance->waiting_list)) {
                     item = WaitingList_pop_front(instance->waiting_list);
                     WaitingList_init_field(item);
                 }
+
                 FURI_CRITICAL_EXIT();
+
                 if(item) {
                     while(true) {
                         FuriEventLoopProcessStatus ret =
@@ -189,13 +158,23 @@ void furi_event_loop_run(FuriEventLoop* instance) {
                         }
                     }
                 }
+
+                furi_event_loop_restore_flags(instance, flags & ~FuriEventLoopFlagEvent);
+
+            } else if(flags & FuriEventLoopFlagTimer) {
+                furi_event_loop_process_timer_queue(instance);
+                furi_event_loop_restore_flags(instance, flags & ~FuriEventLoopFlagTimer);
+
+            } else if(flags & FuriEventLoopFlagPending) {
+                furi_event_loop_process_pending_callbacks(instance);
+
+            } else {
+                furi_crash();
             }
-        } else {
-            if(instance->tick_callback) {
-                instance->tick_callback(instance->tick_callback_context);
-            }
+
+        } else if(!furi_event_loop_process_expired_timers(instance)) {
+            furi_event_loop_process_tick(instance);
         }
-        instance->state = FuriEventLoopStateIdle;
     }
 
     furi_thread_set_signal_callback(instance->thread_id, NULL, NULL);
@@ -208,20 +187,33 @@ void furi_event_loop_stop(FuriEventLoop* instance) {
         instance->thread_id, FURI_EVENT_LOOP_FLAG_NOTIFY_INDEX, FuriEventLoopFlagStop, eSetBits);
 }
 
-void furi_event_loop_tick_set(
+/*
+ * Public deferred function call API
+ */
+
+void furi_event_loop_pend_callback(
     FuriEventLoop* instance,
-    uint32_t interval,
-    FuriEventLoopTickCallback callback,
+    FuriEventLoopPendingCallback callback,
     void* context) {
     furi_check(instance);
     furi_check(instance->thread_id == furi_thread_get_current_id());
-    furi_check(callback ? interval > 0 : true);
+    furi_check(callback);
 
-    instance->tick_interval = interval;
-    instance->tick_callback = callback;
-    instance->tick_callback_context = context;
+    const FuriEventLoopPendingQueueItem item = {
+        .callback = callback,
+        .context = context,
+    };
+
+    PendingQueue_push_front(instance->pending_queue, item);
+
+    xTaskNotifyIndexed(
+        instance->thread_id, FURI_EVENT_LOOP_FLAG_NOTIFY_INDEX, FuriEventLoopFlagPending, eSetBits);
 }
 
+/*
+ * Message queue API
+ */
+
 void furi_event_loop_message_queue_subscribe(
     FuriEventLoop* instance,
     FuriMessageQueue* message_queue,
@@ -230,7 +222,7 @@ void furi_event_loop_message_queue_subscribe(
     void* context) {
     furi_check(instance);
     furi_check(instance->thread_id == furi_thread_get_current_id());
-    furi_check(instance->state == FuriEventLoopStateIdle);
+    furi_check(instance->state == FuriEventLoopStateStopped);
     furi_check(message_queue);
 
     FURI_CRITICAL_ENTER();
@@ -267,7 +259,7 @@ void furi_event_loop_message_queue_unsubscribe(
     FuriEventLoop* instance,
     FuriMessageQueue* message_queue) {
     furi_check(instance);
-    furi_check(instance->state == FuriEventLoopStateIdle);
+    furi_check(instance->state == FuriEventLoopStateStopped);
     furi_check(instance->thread_id == furi_thread_get_current_id());
 
     FURI_CRITICAL_ENTER();

furi/core/event_loop.h

@@ -34,7 +34,7 @@ typedef struct FuriEventLoop FuriEventLoop;
  * Couple things to keep in mind:
  * - You can have 1 event_loop per 1 thread
  * - You can not use event_loop instance in the other thread
- * - Do not use blocking api to query object delegated to Event Loop
+ * - Do not use blocking API to query object delegated to Event Loop
  *
  * @return     The Event Loop instance
  */
@@ -72,8 +72,10 @@ typedef void (*FuriEventLoopTickCallback)(void* context);
 
 /** Set Event Loop tick callback
  *
- * Tick callback called after specified inactivity time. It's not periodic. If
- * Event Loop is busy then ticks will be skipped.
+ * Tick callback is called periodically after specified inactivity time.
+ * It acts like a low-priority timer: it will only fire if there is time
+ * left after processing the synchronization primitives and the regular timers.
+ * Therefore, it is not monotonic: ticks will be skipped if the event loop is busy.
  *
  * @param      instance  The Event Loop instance
  * @param[in]  interval  The tick interval
@@ -86,6 +88,32 @@ void furi_event_loop_tick_set(
     FuriEventLoopTickCallback callback,
     void* context);
 
+/*
+ * Deferred function call API
+ */
+
+/**
+ * @brief Timer callback type for functions to be called in a deferred manner.
+ *
+ * @param[in,out] context pointer to a user-specific object that was provided during
+ *                        furi_event_loop_pend_callback() call
+ */
+typedef void (*FuriEventLoopPendingCallback)(void* context);
+
+/**
+ * @brief Call a function when all preceding timer commands are processed
+ *
+ * This function may be useful to call another function when the event loop has been started.
+ *
+ * @param[in,out] instance pointer to the current FuriEventLoop instance
+ * @param[in] callback pointer to the callback to be executed when previous commands have been processed
+ * @param[in,out] context pointer to a user-specific object (will be passed to the callback)
+ */
+void furi_event_loop_pend_callback(
+    FuriEventLoop* instance,
+    FuriEventLoopPendingCallback callback,
+    void* context);
+
 /*
  * Message queue related APIs
  */

furi/core/event_loop_i.h

@@ -1,35 +1,97 @@
 #pragma once
 
 #include "event_loop.h"
+#include "event_loop_link_i.h"
+#include "event_loop_timer_i.h"
+#include "event_loop_tick_i.h"
 
-#ifdef __cplusplus
-extern "C" {
-#endif
+#include <m-list.h>
+#include <m-bptree.h>
+#include <m-i-list.h>
 
-typedef struct FuriEventLoopItem FuriEventLoopItem;
+#include "thread.h"
 
-/* Link between Event Loop  */
+struct FuriEventLoopItem {
+    // Source
+    FuriEventLoop* owner;
+
+    // Tracking item
+    const FuriEventLoopContract* contract;
+    void* object;
+    FuriEventLoopEvent event;
+
+    // Callback and context
+    FuriEventLoopMessageQueueCallback callback;
+    void* callback_context;
+
+    // Waiting list
+    ILIST_INTERFACE(WaitingList, struct FuriEventLoopItem);
+};
+
+ILIST_DEF(WaitingList, FuriEventLoopItem, M_POD_OPLIST)
+
+/* Event Loop RB tree */
+#define FURI_EVENT_LOOP_TREE_RANK (4)
+
+BPTREE_DEF2( // NOLINT
+    FuriEventLoopTree,
+    FURI_EVENT_LOOP_TREE_RANK,
+    void*, /* pointer to object we track */
+    M_PTR_OPLIST,
+    FuriEventLoopItem*, /* pointer to the FuriEventLoopItem */
+    M_PTR_OPLIST)
+
+#define M_OPL_FuriEventLoopTree_t() BPTREE_OPLIST(FuriEventLoopTree, M_POD_OPLIST)
+
+#define FURI_EVENT_LOOP_FLAG_NOTIFY_INDEX (2)
+
+typedef enum {
+    FuriEventLoopFlagEvent = (1 << 0),
+    FuriEventLoopFlagStop = (1 << 1),
+    FuriEventLoopFlagTimer = (1 << 2),
+    FuriEventLoopFlagPending = (1 << 3),
+} FuriEventLoopFlag;
+
+#define FuriEventLoopFlagAll                                                   \
+    (FuriEventLoopFlagEvent | FuriEventLoopFlagStop | FuriEventLoopFlagTimer | \
+     FuriEventLoopFlagPending)
+
+typedef enum {
+    FuriEventLoopProcessStatusComplete,
+    FuriEventLoopProcessStatusIncomplete,
+    FuriEventLoopProcessStatusAgain,
+} FuriEventLoopProcessStatus;
+
+typedef enum {
+    FuriEventLoopStateStopped,
+    FuriEventLoopStateIdle,
+    FuriEventLoopStateProcessing,
+} FuriEventLoopState;
 
 typedef struct {
-    FuriEventLoopItem* item_in;
-    FuriEventLoopItem* item_out;
-} FuriEventLoopLink;
+    FuriEventLoopPendingCallback callback;
+    void* context;
+} FuriEventLoopPendingQueueItem;
 
-void furi_event_loop_link_notify(FuriEventLoopLink* instance, FuriEventLoopEvent event);
+LIST_DUAL_PUSH_DEF(PendingQueue, FuriEventLoopPendingQueueItem, M_POD_OPLIST)
 
-/* Contract between event loop and an object */
+struct FuriEventLoop {
+    // Only works if all operations are done from the same thread
+    FuriThreadId thread_id;
 
-typedef FuriEventLoopLink* (*FuriEventLoopContractGetLink)(void* object);
+    // Poller state
+    volatile FuriEventLoopState state;
 
-typedef uint32_t (*FuriEventLoopContractGetLevel)(void* object, FuriEventLoopEvent event);
+    // Event handling
+    FuriEventLoopTree_t tree;
+    WaitingList_t waiting_list;
 
-typedef struct {
-    const FuriEventLoopContractGetLink get_link;
-    const FuriEventLoopContractGetLevel get_level;
-} FuriEventLoopContract;
-
-bool furi_event_loop_signal_callback(uint32_t signal, void* arg, void* context);
-
-#ifdef __cplusplus
-}
-#endif
+    // Active timer list
+    TimerList_t timer_list;
+    // Timer request queue
+    TimerQueue_t timer_queue;
+    // Pending callback queue
+    PendingQueue_t pending_queue;
+    // Tick event
+    FuriEventLoopTick tick;
+};

furi/core/event_loop_link_i.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include "event_loop.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct FuriEventLoopItem FuriEventLoopItem;
+
+/* Link between Event Loop  */
+
+typedef struct {
+    FuriEventLoopItem* item_in;
+    FuriEventLoopItem* item_out;
+} FuriEventLoopLink;
+
+void furi_event_loop_link_notify(FuriEventLoopLink* instance, FuriEventLoopEvent event);
+
+/* Contract between event loop and an object */
+
+typedef FuriEventLoopLink* (*FuriEventLoopContractGetLink)(void* object);
+
+typedef uint32_t (*FuriEventLoopContractGetLevel)(void* object, FuriEventLoopEvent event);
+
+typedef struct {
+    const FuriEventLoopContractGetLink get_link;
+    const FuriEventLoopContractGetLevel get_level;
+} FuriEventLoopContract;
+
+bool furi_event_loop_signal_callback(uint32_t signal, void* arg, void* context);
+
+#ifdef __cplusplus
+}
+#endif

furi/core/event_loop_tick.c

@@ -0,0 +1,69 @@
+#include "event_loop_i.h"
+
+#include <FreeRTOS.h>
+#include <task.h>
+
+#include <furi.h>
+
+/**
+ * Private functions
+ */
+
+static inline uint32_t furi_event_loop_tick_get_elapsed_time(const FuriEventLoop* instance) {
+    return xTaskGetTickCount() - instance->tick.prev_time;
+}
+
+static inline uint32_t furi_event_loop_tick_get_remaining_time(const FuriEventLoop* instance) {
+    const uint32_t elapsed_time = furi_event_loop_tick_get_elapsed_time(instance);
+    return elapsed_time < instance->tick.interval ? instance->tick.interval - elapsed_time : 0;
+}
+
+static inline bool furi_event_loop_tick_is_expired(const FuriEventLoop* instance) {
+    return furi_event_loop_tick_get_elapsed_time(instance) >= instance->tick.interval;
+}
+
+/*
+ * Private tick API
+ */
+
+void furi_event_loop_init_tick(FuriEventLoop* instance) {
+    if(instance->tick.callback) {
+        instance->tick.prev_time = xTaskGetTickCount();
+    }
+}
+
+void furi_event_loop_process_tick(FuriEventLoop* instance) {
+    if(instance->tick.callback && furi_event_loop_tick_is_expired(instance)) {
+        instance->tick.prev_time += instance->tick.interval;
+        instance->tick.callback(instance->tick.callback_context);
+    }
+}
+
+uint32_t furi_event_loop_get_tick_wait_time(const FuriEventLoop* instance) {
+    uint32_t wait_time = FuriWaitForever;
+
+    if(instance->tick.callback) {
+        wait_time = furi_event_loop_tick_get_remaining_time(instance);
+    }
+
+    return wait_time;
+}
+
+/*
+ * Public tick API
+ */
+
+void furi_event_loop_tick_set(
+    FuriEventLoop* instance,
+    uint32_t interval,
+    FuriEventLoopTickCallback callback,
+    void* context) {
+    furi_check(instance);
+    furi_check(instance->thread_id == furi_thread_get_current_id());
+    furi_check(callback ? interval > 0 : true);
+
+    instance->tick.callback = callback;
+    instance->tick.callback_context = context;
+    instance->tick.interval = interval;
+    instance->tick.prev_time = xTaskGetTickCount();
+}

furi/core/event_loop_tick_i.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include "event_loop.h"
+
+typedef struct {
+    uint32_t interval;
+    uint32_t prev_time;
+    FuriEventLoopTickCallback callback;
+    void* callback_context;
+} FuriEventLoopTick;
+
+void furi_event_loop_init_tick(FuriEventLoop* instance);
+
+void furi_event_loop_process_tick(FuriEventLoop* instance);
+
+uint32_t furi_event_loop_get_tick_wait_time(const FuriEventLoop* instance);

furi/core/event_loop_timer.c

@@ -0,0 +1,215 @@
+#include "event_loop_i.h"
+
+#include <FreeRTOS.h>
+#include <task.h>
+
+#include <furi.h>
+
+/*
+ * Private functions
+ */
+
+static inline uint32_t furi_event_loop_timer_get_elapsed_time(const FuriEventLoopTimer* timer) {
+    return xTaskGetTickCount() - timer->start_time;
+}
+
+static inline uint32_t
+    furi_event_loop_timer_get_remaining_time_private(const FuriEventLoopTimer* timer) {
+    const uint32_t elapsed_time = furi_event_loop_timer_get_elapsed_time(timer);
+    return elapsed_time < timer->interval ? timer->interval - elapsed_time : 0;
+}
+
+static inline bool furi_event_loop_timer_is_expired(const FuriEventLoopTimer* timer) {
+    return furi_event_loop_timer_get_elapsed_time(timer) >= timer->interval;
+}
+
+static void furi_event_loop_schedule_timer(FuriEventLoop* instance, FuriEventLoopTimer* timer) {
+    FuriEventLoopTimer* timer_pos = NULL;
+
+    FURI_CRITICAL_ENTER();
+
+    const uint32_t remaining_time = furi_event_loop_timer_get_remaining_time_private(timer);
+
+    TimerList_it_t it;
+    for(TimerList_it_last(it, instance->timer_list); !TimerList_end_p(it);
+        TimerList_previous(it)) {
+        FuriEventLoopTimer* tmp = TimerList_ref(it);
+        if(remaining_time >= furi_event_loop_timer_get_remaining_time_private(tmp)) {
+            timer_pos = tmp;
+            break;
+        }
+    }
+
+    FURI_CRITICAL_EXIT();
+
+    if(timer_pos) {
+        TimerList_push_after(timer_pos, timer);
+    } else {
+        TimerList_push_front(instance->timer_list, timer);
+    }
+    // At this point, TimerList_front() points to the first timer to expire
+}
+
+static void furi_event_loop_timer_enqueue_request(
+    FuriEventLoopTimer* timer,
+    FuriEventLoopTimerRequest request) {
+    if(timer->request != FuriEventLoopTimerRequestNone) {
+        // You cannot change your mind after calling furi_event_loop_timer_free()
+        furi_check(timer->request != FuriEventLoopTimerRequestFree);
+        TimerQueue_unlink(timer);
+    }
+
+    timer->request = request;
+
+    FuriEventLoop* instance = timer->owner;
+    TimerQueue_push_back(instance->timer_queue, timer);
+
+    xTaskNotifyIndexed(
+        instance->thread_id, FURI_EVENT_LOOP_FLAG_NOTIFY_INDEX, FuriEventLoopFlagTimer, eSetBits);
+}
+
+/*
+ * Private API
+ */
+
+uint32_t furi_event_loop_get_timer_wait_time(const FuriEventLoop* instance) {
+    uint32_t wait_time = FuriWaitForever;
+
+    if(!TimerList_empty_p(instance->timer_list)) {
+        FuriEventLoopTimer* timer = TimerList_front(instance->timer_list);
+        wait_time = furi_event_loop_timer_get_remaining_time_private(timer);
+    }
+
+    return wait_time;
+}
+
+void furi_event_loop_process_timer_queue(FuriEventLoop* instance) {
+    while(!TimerQueue_empty_p(instance->timer_queue)) {
+        FuriEventLoopTimer* timer = TimerQueue_pop_front(instance->timer_queue);
+
+        if(timer->active) {
+            TimerList_unlink(timer);
+        }
+
+        if(timer->request == FuriEventLoopTimerRequestStart) {
+            timer->active = true;
+            timer->interval = timer->next_interval;
+            timer->start_time = xTaskGetTickCount();
+            timer->request = FuriEventLoopTimerRequestNone;
+
+            furi_event_loop_schedule_timer(instance, timer);
+
+        } else if(timer->request == FuriEventLoopTimerRequestStop) {
+            timer->active = false;
+            timer->request = FuriEventLoopTimerRequestNone;
+
+        } else if(timer->request == FuriEventLoopTimerRequestFree) {
+            free(timer);
+
+        } else {
+            furi_crash();
+        }
+    }
+}
+
+bool furi_event_loop_process_expired_timers(FuriEventLoop* instance) {
+    if(TimerList_empty_p(instance->timer_list)) {
+        return false;
+    }
+    // The front() element contains the earliest-expiring timer
+    FuriEventLoopTimer* timer = TimerList_front(instance->timer_list);
+
+    if(!furi_event_loop_timer_is_expired(timer)) {
+        return false;
+    }
+
+    TimerList_unlink(timer);
+
+    if(timer->periodic) {
+        const uint32_t num_events =
+            furi_event_loop_timer_get_elapsed_time(timer) / timer->interval;
+
+        timer->start_time += timer->interval * num_events;
+        furi_event_loop_schedule_timer(instance, timer);
+
+    } else {
+        timer->active = false;
+    }
+
+    timer->callback(timer->context);
+    return true;
+}
+
+/*
+ * Public timer API
+ */
+
+FuriEventLoopTimer* furi_event_loop_timer_alloc(
+    FuriEventLoop* instance,
+    FuriEventLoopTimerCallback callback,
+    FuriEventLoopTimerType type,
+    void* context) {
+    furi_check(instance);
+    furi_check(instance->thread_id == furi_thread_get_current_id());
+    furi_check(callback);
+    furi_check(type <= FuriEventLoopTimerTypePeriodic);
+
+    FuriEventLoopTimer* timer = malloc(sizeof(FuriEventLoopTimer));
+
+    timer->owner = instance;
+    timer->callback = callback;
+    timer->context = context;
+    timer->periodic = (type == FuriEventLoopTimerTypePeriodic);
+
+    TimerList_init_field(timer);
+    TimerQueue_init_field(timer);
+
+    return timer;
+}
+
+void furi_event_loop_timer_free(FuriEventLoopTimer* timer) {
+    furi_check(timer);
+    furi_check(timer->owner->thread_id == furi_thread_get_current_id());
+
+    furi_event_loop_timer_enqueue_request(timer, FuriEventLoopTimerRequestFree);
+}
+
+void furi_event_loop_timer_start(FuriEventLoopTimer* timer, uint32_t interval) {
+    furi_check(timer);
+    furi_check(timer->owner->thread_id == furi_thread_get_current_id());
+
+    timer->next_interval = interval;
+
+    furi_event_loop_timer_enqueue_request(timer, FuriEventLoopTimerRequestStart);
+}
+
+void furi_event_loop_timer_restart(FuriEventLoopTimer* timer) {
+    furi_check(timer);
+    furi_check(timer->owner->thread_id == furi_thread_get_current_id());
+
+    timer->next_interval = timer->interval;
+
+    furi_event_loop_timer_enqueue_request(timer, FuriEventLoopTimerRequestStart);
+}
+
+void furi_event_loop_timer_stop(FuriEventLoopTimer* timer) {
+    furi_check(timer);
+    furi_check(timer->owner->thread_id == furi_thread_get_current_id());
+
+    furi_event_loop_timer_enqueue_request(timer, FuriEventLoopTimerRequestStop);
+}
+
+uint32_t furi_event_loop_timer_get_remaining_time(const FuriEventLoopTimer* timer) {
+    furi_check(timer);
+    return furi_event_loop_timer_get_remaining_time_private(timer);
+}
+
+uint32_t furi_event_loop_timer_get_interval(const FuriEventLoopTimer* timer) {
+    furi_check(timer);
+    return timer->interval;
+}
+
+bool furi_event_loop_timer_is_running(const FuriEventLoopTimer* timer) {
+    furi_check(timer);
+    return timer->active;
+}

furi/core/event_loop_timer.h

@@ -0,0 +1,118 @@
+/**
+ * @file event_loop_timer.h
+ * @brief Software timer functionality for FuriEventLoop.
+ */
+
+#pragma once
+
+#include "event_loop.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Enumeration of possible timer types.
+ */
+typedef enum {
+    FuriEventLoopTimerTypeOnce = 0, /**< One-shot timer. */
+    FuriEventLoopTimerTypePeriodic = 1, /**< Repeating timer. */
+} FuriEventLoopTimerType;
+
+/**
+ * @brief Timer callback type for functions to be called when a timer expires.
+ *
+ * In the timer callback, it is ALLOWED:
+ * - To start, stop, or restart an existing timer,
+ * - To create new timers using furi_event_loop_timer_alloc(),
+ * - To delete timers using furi_event_loop_timer_free().
+ *
+ * @param[in,out] context pointer to a user-specific object that was provided during timer creation
+ */
+typedef void (*FuriEventLoopTimerCallback)(void* context);
+
+/**
+ * @brief Opaque event loop timer type.
+ */
+typedef struct FuriEventLoopTimer FuriEventLoopTimer;
+
+/**
+ * @brief Create a new event loop timer instance.
+ *
+ * @param[in,out] instance pointer to the current FuriEventLoop instance
+ * @param[in] callback pointer to the callback function to be executed upon timer timeout
+ * @param[in] type timer type value to determine its behavior (single-shot or periodic)
+ * @param[in,out] context pointer to a user-specific object (will be passed to the callback)
+ * @returns pointer to the created timer instance
+ */
+FuriEventLoopTimer* furi_event_loop_timer_alloc(
+    FuriEventLoop* instance,
+    FuriEventLoopTimerCallback callback,
+    FuriEventLoopTimerType type,
+    void* context);
+
+/**
+ * @brief Delete an event loop timer instance.
+ *
+ * @warning The user code MUST call furi_event_loop_timer_free() on ALL instances
+ *          associated with the current event loop BEFORE calling furi_event_loop_free().
+ *          The event loop may EITHER be running OR stopped when the timers are being deleted.
+ *
+ * @param[in,out] timer pointer to the timer instance to be deleted
+ */
+void furi_event_loop_timer_free(FuriEventLoopTimer* timer);
+
+/**
+ * @brief Start a timer or restart it with a new interval.
+ *
+ * @param[in,out] timer pointer to the timer instance to be (re)started
+ * @param[in] interval timer interval in ticks
+ */
+void furi_event_loop_timer_start(FuriEventLoopTimer* timer, uint32_t interval);
+
+/**
+ * @brief Restart a timer with the previously set interval.
+ *
+ * @param[in,out] timer pointer to the timer instance to be restarted
+ */
+void furi_event_loop_timer_restart(FuriEventLoopTimer* timer);
+
+/**
+ * @brief Stop a timer without firing its callback.
+ *
+ * It is safe to call this function on an already stopped timer (it will do nothing).
+ *
+ * @param[in,out] timer pointer to the timer instance to be stopped
+ */
+void furi_event_loop_timer_stop(FuriEventLoopTimer* timer);
+
+/**
+ * @brief Get the time remaining before the timer becomes expires.
+ *
+ * For stopped or expired timers, this function returns 0.
+ *
+ * @param[in] timer pointer to the timer to be queried
+ * @returns remaining time in ticks
+ */
+uint32_t furi_event_loop_timer_get_remaining_time(const FuriEventLoopTimer* timer);
+
+/**
+ * @brief Get the timer interval.
+ *
+ * @param[in] timer pointer to the timer to be queried
+ * @returns timer interval in ticks
+ */
+uint32_t furi_event_loop_timer_get_interval(const FuriEventLoopTimer* timer);
+
+/**
+ * @brief Check if the timer is currently running.
+ *
+ * A timer is considered running if it has not expired yet.
+ * @param[in] timer pointer to the timer to be queried
+ * @returns true if the timer is running, false otherwise
+ */
+bool furi_event_loop_timer_is_running(const FuriEventLoopTimer* timer);
+
+#ifdef __cplusplus
+}
+#endif

furi/core/event_loop_timer_i.h

@@ -0,0 +1,43 @@
+#pragma once
+
+#include "event_loop_timer.h"
+
+#include <m-i-list.h>
+
+typedef enum {
+    FuriEventLoopTimerRequestNone,
+    FuriEventLoopTimerRequestStart,
+    FuriEventLoopTimerRequestStop,
+    FuriEventLoopTimerRequestFree,
+} FuriEventLoopTimerRequest;
+
+struct FuriEventLoopTimer {
+    FuriEventLoop* owner;
+
+    FuriEventLoopTimerCallback callback;
+    void* context;
+
+    uint32_t interval;
+    uint32_t start_time;
+    uint32_t next_interval;
+
+    // Interface for the active timer list
+    ILIST_INTERFACE(TimerList, FuriEventLoopTimer);
+
+    // Interface for the timer request queue
+    ILIST_INTERFACE(TimerQueue, FuriEventLoopTimer);
+
+    FuriEventLoopTimerRequest request;
+
+    bool active;
+    bool periodic;
+};
+
+ILIST_DEF(TimerList, FuriEventLoopTimer, M_POD_OPLIST)
+ILIST_DEF(TimerQueue, FuriEventLoopTimer, M_POD_OPLIST)
+
+uint32_t furi_event_loop_get_timer_wait_time(const FuriEventLoop* instance);
+
+void furi_event_loop_process_timer_queue(FuriEventLoop* instance);
+
+bool furi_event_loop_process_expired_timers(FuriEventLoop* instance);

furi/core/message_queue.c

@@ -1,5 +1,11 @@
 #include "message_queue_i.h"
 
+#include <FreeRTOS.h>
+#include <queue.h>
+
+#include "kernel.h"
+#include "check.h"
+
 // Internal FreeRTOS member names
 #define uxMessagesWaiting uxDummy4[0]
 #define uxLength uxDummy4[1]

furi/core/message_queue_i.h

@@ -1,12 +1,6 @@
 #pragma once
 
 #include "message_queue.h"
-
-#include "kernel.h"
-#include "event_loop_i.h"
-#include "check.h"
-
-#include <FreeRTOS.h>
-#include <queue.h>
+#include "event_loop_link_i.h"
 
 extern const FuriEventLoopContract furi_message_queue_event_loop_contract;

furi/furi.h

@@ -5,6 +5,7 @@
 #include "core/check.h"
 #include "core/common_defines.h"
 #include "core/event_loop.h"
+#include "core/event_loop_timer.h"
 #include "core/event_flag.h"
 #include "core/kernel.h"
 #include "core/log.h"

targets/f18/api_symbols.csv

@@ -1,5 +1,5 @@
 entry,status,name,type,params
-Version,+,67.1,,
+Version,+,67.2,,
 Header,+,applications/services/bt/bt_service/bt.h,,
 Header,+,applications/services/bt/bt_service/bt_keys_storage.h,,
 Header,+,applications/services/cli/cli.h,,
@@ -1105,13 +1105,22 @@ Function,+,furi_event_flag_free,void,FuriEventFlag*
 Function,+,furi_event_flag_get,uint32_t,FuriEventFlag*
 Function,+,furi_event_flag_set,uint32_t,"FuriEventFlag*, uint32_t"
 Function,+,furi_event_flag_wait,uint32_t,"FuriEventFlag*, uint32_t, uint32_t, uint32_t"
-Function,-,furi_event_loop_alloc,FuriEventLoop*,
-Function,-,furi_event_loop_free,void,FuriEventLoop*
-Function,-,furi_event_loop_message_queue_subscribe,void,"FuriEventLoop*, FuriMessageQueue*, FuriEventLoopEvent, FuriEventLoopMessageQueueCallback, void*"
-Function,-,furi_event_loop_message_queue_unsubscribe,void,"FuriEventLoop*, FuriMessageQueue*"
-Function,-,furi_event_loop_run,void,FuriEventLoop*
-Function,-,furi_event_loop_stop,void,FuriEventLoop*
-Function,-,furi_event_loop_tick_set,void,"FuriEventLoop*, uint32_t, FuriEventLoopTickCallback, void*"
+Function,+,furi_event_loop_alloc,FuriEventLoop*,
+Function,+,furi_event_loop_free,void,FuriEventLoop*
+Function,+,furi_event_loop_message_queue_subscribe,void,"FuriEventLoop*, FuriMessageQueue*, FuriEventLoopEvent, FuriEventLoopMessageQueueCallback, void*"
+Function,+,furi_event_loop_message_queue_unsubscribe,void,"FuriEventLoop*, FuriMessageQueue*"
+Function,+,furi_event_loop_pend_callback,void,"FuriEventLoop*, FuriEventLoopPendingCallback, void*"
+Function,+,furi_event_loop_run,void,FuriEventLoop*
+Function,+,furi_event_loop_stop,void,FuriEventLoop*
+Function,+,furi_event_loop_tick_set,void,"FuriEventLoop*, uint32_t, FuriEventLoopTickCallback, void*"
+Function,+,furi_event_loop_timer_alloc,FuriEventLoopTimer*,"FuriEventLoop*, FuriEventLoopTimerCallback, FuriEventLoopTimerType, void*"
+Function,+,furi_event_loop_timer_free,void,FuriEventLoopTimer*
+Function,+,furi_event_loop_timer_get_interval,uint32_t,const FuriEventLoopTimer*
+Function,+,furi_event_loop_timer_get_remaining_time,uint32_t,const FuriEventLoopTimer*
+Function,+,furi_event_loop_timer_is_running,_Bool,const FuriEventLoopTimer*
+Function,+,furi_event_loop_timer_restart,void,FuriEventLoopTimer*
+Function,+,furi_event_loop_timer_start,void,"FuriEventLoopTimer*, uint32_t"
+Function,+,furi_event_loop_timer_stop,void,FuriEventLoopTimer*
 Function,+,furi_get_tick,uint32_t,
 Function,+,furi_hal_adc_acquire,FuriHalAdcHandle*,
 Function,+,furi_hal_adc_configure,void,FuriHalAdcHandle*

targets/f7/api_symbols.csv

@@ -1,5 +1,5 @@
 entry,status,name,type,params
-Version,+,67.1,,
+Version,+,67.2,,
 Header,+,applications/drivers/subghz/cc1101_ext/cc1101_ext_interconnect.h,,
 Header,+,applications/services/bt/bt_service/bt.h,,
 Header,+,applications/services/bt/bt_service/bt_keys_storage.h,,
@@ -1210,13 +1210,22 @@ Function,+,furi_event_flag_free,void,FuriEventFlag*
 Function,+,furi_event_flag_get,uint32_t,FuriEventFlag*
 Function,+,furi_event_flag_set,uint32_t,"FuriEventFlag*, uint32_t"
 Function,+,furi_event_flag_wait,uint32_t,"FuriEventFlag*, uint32_t, uint32_t, uint32_t"
-Function,-,furi_event_loop_alloc,FuriEventLoop*,
-Function,-,furi_event_loop_free,void,FuriEventLoop*
-Function,-,furi_event_loop_message_queue_subscribe,void,"FuriEventLoop*, FuriMessageQueue*, FuriEventLoopEvent, FuriEventLoopMessageQueueCallback, void*"
-Function,-,furi_event_loop_message_queue_unsubscribe,void,"FuriEventLoop*, FuriMessageQueue*"
-Function,-,furi_event_loop_run,void,FuriEventLoop*
-Function,-,furi_event_loop_stop,void,FuriEventLoop*
-Function,-,furi_event_loop_tick_set,void,"FuriEventLoop*, uint32_t, FuriEventLoopTickCallback, void*"
+Function,+,furi_event_loop_alloc,FuriEventLoop*,
+Function,+,furi_event_loop_free,void,FuriEventLoop*
+Function,+,furi_event_loop_message_queue_subscribe,void,"FuriEventLoop*, FuriMessageQueue*, FuriEventLoopEvent, FuriEventLoopMessageQueueCallback, void*"
+Function,+,furi_event_loop_message_queue_unsubscribe,void,"FuriEventLoop*, FuriMessageQueue*"
+Function,+,furi_event_loop_pend_callback,void,"FuriEventLoop*, FuriEventLoopPendingCallback, void*"
+Function,+,furi_event_loop_run,void,FuriEventLoop*
+Function,+,furi_event_loop_stop,void,FuriEventLoop*
+Function,+,furi_event_loop_tick_set,void,"FuriEventLoop*, uint32_t, FuriEventLoopTickCallback, void*"
+Function,+,furi_event_loop_timer_alloc,FuriEventLoopTimer*,"FuriEventLoop*, FuriEventLoopTimerCallback, FuriEventLoopTimerType, void*"
+Function,+,furi_event_loop_timer_free,void,FuriEventLoopTimer*
+Function,+,furi_event_loop_timer_get_interval,uint32_t,const FuriEventLoopTimer*
+Function,+,furi_event_loop_timer_get_remaining_time,uint32_t,const FuriEventLoopTimer*
+Function,+,furi_event_loop_timer_is_running,_Bool,const FuriEventLoopTimer*
+Function,+,furi_event_loop_timer_restart,void,FuriEventLoopTimer*
+Function,+,furi_event_loop_timer_start,void,"FuriEventLoopTimer*, uint32_t"
+Function,+,furi_event_loop_timer_stop,void,FuriEventLoopTimer*
 Function,+,furi_get_tick,uint32_t,
 Function,+,furi_hal_adc_acquire,FuriHalAdcHandle*,
 Function,+,furi_hal_adc_configure,void,FuriHalAdcHandle*