add regular scheduled functions, now also callable on yield()

added bool schedule_function_us(std::function<bool(void)> fn, uint32_t repeat_us)
lambda must return true to be not removed from the schedule function list
if repeat_us is 0, then the function is called only once.

Legacy schedule_function() is preserved

Linked list management is simplified

This addition allows network drivers like ethernet chips on lwIP to be regularly called
- even if some user code loops on receiving data without getting out from main loop
  (callable from yield())
- without the need to call the driver handling function
  (transparent)

This may be also applicable with common libraries (mDNS, Webserver, )

Author: d-a-v

cores/esp8266/FunctionalInterrupt.cpp

@@ -3,6 +3,8 @@
 #include "Arduino.h"
 #include <ScheduledFunctions.h>
 
+static ScheduledFunctions* scheduledInterrupts;
+
 // Duplicate typedefs from core_esp8266_wiring_digital_c
 typedef void (*voidFuncPtr)(void);
 typedef void (*voidFuncPtrArg)(void*);

cores/esp8266/FunctionalInterrupt.h

@@ -29,7 +29,6 @@ struct ArgStructure {
 	FunctionInfo* functionInfo = nullptr;
 };
 
-static ScheduledFunctions* scheduledInterrupts;
 void attachInterrupt(uint8_t pin, std::function<void(void)> intRoutine, int mode);
 void attachScheduledInterrupt(uint8_t pin, std::function<void(InterruptInfo)> scheduledIntRoutine, int mode);
 

cores/esp8266/Schedule.cpp

@@ -1,16 +1,19 @@
 #include "Schedule.h"
+#include "PolledTimeout.h"
+
+typedef std::function<bool(void)> mFuncT;
 
 struct scheduled_fn_t
 {
     scheduled_fn_t* mNext;
-    std::function<void(void)> mFunc;
+    mFuncT mFunc;
+    esp8266::polledTimeout::periodicFastUs callNow;
+
+    scheduled_fn_t(): callNow(esp8266::polledTimeout::periodicFastUs::alwaysExpired) { }
 };
 
 static scheduled_fn_t* sFirst = 0;
-static scheduled_fn_t* sLast = 0;
-
 static scheduled_fn_t* sFirstUnused = 0;
-static scheduled_fn_t* sLastUnused = 0;
 
 static int sCount = 0;
 
@@ -20,9 +23,6 @@ static scheduled_fn_t* get_fn() {
     if (sFirstUnused) {
         result = sFirstUnused;
         sFirstUnused = result->mNext;
-        if (sFirstUnused == NULL) {
-            sLastUnused = NULL;
-        }
     }
     // if no unused items, and count not too high, allocate a new one
     else if (sCount != SCHEDULED_FN_MAX_COUNT) {
@@ -35,44 +35,40 @@ static scheduled_fn_t* get_fn() {
 
 static void recycle_fn(scheduled_fn_t* fn)
 {
-    if (!sLastUnused) {
-        sFirstUnused = fn;
-    }
-    else {
-        sLastUnused->mNext = fn;
-    }
-    fn->mNext = NULL;
-    sLastUnused = fn;
+    fn->mNext = sFirstUnused;
+    sFirstUnused = fn;
 }
 
-bool schedule_function(std::function<void(void)> fn)
+bool schedule_function_us(mFuncT fn, uint32_t repeat_us)
 {
     scheduled_fn_t* item = get_fn();
     if (!item) {
         return false;
     }
     item->mFunc = fn;
-    item->mNext = NULL;
-    if (!sFirst) {
-        sFirst = item;
-    }
-    else {
-        sLast->mNext = item;
-    }
-    sLast = item;
+    item->mNext = sFirst;
+    sFirst = item;
+    if (repeat_us)
+        item->callNow.reset(repeat_us);
     return true;
 }
 
+bool schedule_function(std::function<void(void)> fn)
+{
+    return schedule_function_us([&fn](){ fn(); return false; }, 0);
+}
+
 void run_scheduled_functions()
 {
-	scheduled_fn_t* rFirst = sFirst;
-	sFirst = NULL;
-	sLast  = NULL;
-    while (rFirst) {
-        scheduled_fn_t* item = rFirst;
-        rFirst = item->mNext;
-        item->mFunc();
-        item->mFunc = std::function<void(void)>();
-        recycle_fn(item);
+    scheduled_fn_t* toCall = sFirst;
+    while (toCall) {
+        scheduled_fn_t* item = toCall;
+        toCall = item->mNext;
+        if (item->callNow && !item->mFunc()) {
+            if (sFirst == item)
+                sFirst = item->mNext;
+            item->mFunc = mFuncT();
+            recycle_fn(item);
+        }
     }
 }

cores/esp8266/Schedule.h

@@ -6,20 +6,24 @@
 #define SCHEDULED_FN_MAX_COUNT 32
 #define SCHEDULED_FN_INITIAL_COUNT 4
 
-// Warning 
-// This API is not considered stable. 
+// Warning
+// This API is not considered stable.
 // Function signatures will change.
 // You have been warned.
 
-// Run given function next time `loop` function returns, 
+// Run given function ONCE next time `loop` function returns,
+// or `yield` is called,
 // or `run_scheduled_functions` is called.
 // Use std::bind to pass arguments to a function, or call a class member function.
 // Note: there is no mechanism for cancelling scheduled functions.
 // Keep that in mind when binding functions to objects which may have short lifetime.
 // Returns false if the number of scheduled functions exceeds SCHEDULED_FN_MAX_COUNT.
 bool schedule_function(std::function<void(void)> fn);
 
-// Run all scheduled functions. 
+// run given function every at least <repeat_us> microseconds until it returns false
+bool schedule_function_us(std::function<bool(void)> fn, uint32_t repeat_us);
+
+// Run all scheduled functions.
 // Use this function if your are not using `loop`, or `loop` does not return
 // on a regular basis.
 void run_scheduled_functions();

cores/esp8266/core_esp8266_main.cpp

@@ -91,13 +91,15 @@ extern "C" void esp_yield() {
 }
 
 extern "C" void esp_schedule() {
+    // always on CONT stack here
+    run_scheduled_functions();
     ets_post(LOOP_TASK_PRIORITY, 0, 0);
 }
 
 extern "C" void __yield() {
     if (cont_can_yield(g_pcont)) {
         esp_schedule();
-        esp_yield();
+        cont_yield(g_pcont); //esp_yield();
     }
     else {
         panic();
@@ -122,7 +124,6 @@ static void loop_wrapper() {
         setup_done = true;
     }
     loop();
-    run_scheduled_functions();
     esp_schedule();
 }