CoroutineScheduler.h

/*
MIT License
 
Copyright (c) 2018 Brian T. Park
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
 
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
 
#ifndef ACE_ROUTINE_COROUTINE_SCHEDULER_H
#define ACE_ROUTINE_COROUTINE_SCHEDULER_H
 
#if ACE_ROUTINE_DEBUG == 1
  #include <Arduino.h> // Serial, Print
#endif
#include "Coroutine.h"
#include "CoroutineProfiler.h"
 
class Print;
 
namespace ace_routine {
 
template <typename T_COROUTINE>
class CoroutineSchedulerTemplate {
  public:
    static void setup() { getScheduler()->setupScheduler(); }
 
    static void setupCoroutines() {
      getScheduler()->setupCoroutinesInternal();
    }
 
    static void loop() { getScheduler()->runCoroutine(); }
 
    static void loopWithProfiler() {
      getScheduler()->runCoroutineWithProfiler();
    }
 
    static void list(Print& printer) {
      getScheduler()->listCoroutines(printer);
    }
 
  private:
    // Disable copy-constructor and assignment operator
    CoroutineSchedulerTemplate(const CoroutineSchedulerTemplate&) = delete;
    CoroutineSchedulerTemplate& operator=(const CoroutineSchedulerTemplate&) =
        delete;
 
    static CoroutineSchedulerTemplate* getScheduler() {
      static CoroutineSchedulerTemplate singletonScheduler;
      return &singletonScheduler;
    }
 
    CoroutineSchedulerTemplate() = default;
 
    void setupScheduler() {
      mCurrent = T_COROUTINE::getRoot();
    }
 
    void setupCoroutinesInternal() {
      for (T_COROUTINE** p = T_COROUTINE::getRoot();
          (*p) != nullptr;
          p = (*p)->getNext()) {
 
        (*p)->setupCoroutine();
      }
    }
 
    void runCoroutine() {
      // If reached the end, start from the beginning again.
      if (*mCurrent == nullptr) {
        mCurrent = T_COROUTINE::getRoot();
        // Return if the list is empty. Checking for a null getRoot() inside the
        // if-statement is deliberate, since it optimizes the common case where
        // the linked list is not empty.
        if (*mCurrent == nullptr) {
          return;
        }
      }
 
      // Handle the coroutine's dispatch back to the last known internal status.
      switch ((*mCurrent)->getStatus()) {
        case T_COROUTINE::kStatusYielding:
        case T_COROUTINE::kStatusDelaying:
          // The coroutine itself knows whether it is yielding or delaying, and
          // its continuation context determines whether to call
          // Coroutine::isDelayExpired(), Coroutine::isDelayMicrosExpired(), or
          // Coroutine::isDelaySecondsExpired().
          (*mCurrent)->runCoroutine();
          break;
 
        case T_COROUTINE::kStatusEnding:
          // mark it terminated
          (*mCurrent)->setTerminated();
          break;
 
        default:
          // For all other cases, just skip to the next coroutine.
          break;
      }
 
      // Go to the next coroutine
      mCurrent = (*mCurrent)->getNext();
    }
 
    /*
     * Run the current coroutine with profiling enabled by calling
     * Coroutine::runCoroutineWithProfiler().
     */
    void runCoroutineWithProfiler() {
      // If reached the end, start from the beginning again.
      if (*mCurrent == nullptr) {
        mCurrent = T_COROUTINE::getRoot();
        // Return if the list is empty. Checking for a null getRoot() inside the
        // if-statement is deliberate, since it optimizes the common case where
        // the linked list is not empty.
        if (*mCurrent == nullptr) {
          return;
        }
      }
 
      // Handle the coroutine's dispatch back to the last known internal status.
      switch ((*mCurrent)->getStatus()) {
        case T_COROUTINE::kStatusYielding:
        case T_COROUTINE::kStatusDelaying:
          // The coroutine itself knows whether it is yielding or delaying, and
          // its continuation context determines whether to call
          // Coroutine::isDelayExpired(), Coroutine::isDelayMicrosExpired(), or
          // Coroutine::isDelaySecondsExpired().
          //
          // This version calls `Coroutine::runCoroutineWithProfiler()` to
          // enable the profiler.
          (*mCurrent)->runCoroutineWithProfiler();
          break;
 
        case T_COROUTINE::kStatusEnding:
          // mark it terminated
          (*mCurrent)->setTerminated();
          break;
 
        default:
          // For all other cases, just skip to the next coroutine.
          break;
      }
 
      // Go to the next coroutine
      mCurrent = (*mCurrent)->getNext();
    }
 
    void listCoroutines(Print& printer) {
      for (T_COROUTINE** p = T_COROUTINE::getRoot(); (*p) != nullptr;
          p = (*p)->getNext()) {
        printer.print(F("Coroutine "));
        (*p)->printNameTo(printer);
        printer.print(F("; status: "));
        (*p)->statusPrintTo(printer);
        printer.println();
      }
    }
 
    // The current coroutine is represented by a pointer to a pointer. This
    // allows the root node to be treated the same as all the other nodes, and
    // simplifies the code that traverses the singly-linked list.
    T_COROUTINE** mCurrent = nullptr;
};
 
using CoroutineScheduler = CoroutineSchedulerTemplate<Coroutine>;
 
}
 
#endif