Fix/asio scheduler cancellation (#81)

* test - AsioScheduler called onTimer after being destructed

Signed-off-by: Alexey-N-Chernyshov <[email protected]>

* fix AsioScheduler

Signed-off-by: Alexey-N-Chernyshov <[email protected]>

* add comment

Signed-off-by: Alexey-N-Chernyshov <[email protected]>

* add correct asio_scheduler cancellation

From boost docs:
"These (scheduled after cancel() called) handlers can no longer be cancelled, and therefore are passed an error code that indicates the successful completion of the wait operation."
Adds shared_pointer flag for cancellation.

Signed-off-by: Alexey-N-Chernyshov <[email protected]>

Author: Alexey-N-Chernyshov

include/libp2p/protocol/common/asio/asio_scheduler.hpp

@@ -14,10 +14,10 @@ namespace libp2p::protocol {
 
   class AsioScheduler : public Scheduler {
    public:
-    ~AsioScheduler() override = default;
-
     AsioScheduler(boost::asio::io_context &io, SchedulerConfig config);
 
+    ~AsioScheduler() override;
+
    private:
     Ticks now() const override;
 
@@ -31,6 +31,17 @@ namespace libp2p::protocol {
     Ticks interval_;
     boost::asio::deadline_timer timer_;
     boost::posix_time::ptime started_;
+
+    /*
+     * Timer callback is canceled
+     *
+     * In case when the timer has already expired when cancel() is called and
+     * the handlers have been invoked or queued for invocation. These handlers
+     * can no longer be cancelled, and therefore are passed an error code that
+     * indicates the successful completion of the wait operation. Cancel is used
+     * to indicate that handler should not be executed.
+     */
+    std::shared_ptr<bool> canceled_;
     std::function<void(const boost::system::error_code &)> timer_cb_;
     std::function<void()> immediate_cb_;
     bool immediate_cb_scheduled_ = false;

src/protocol/common/asio/asio_scheduler.cpp

@@ -15,15 +15,22 @@ namespace libp2p::protocol {
         interval_(config.period_msec),
         timer_(io, boost::posix_time::milliseconds(interval_)),
         started_(boost::posix_time::microsec_clock::local_time()),
-        timer_cb_([this](const boost::system::error_code &error) {
-          if (!error)
+        canceled_(std::make_shared<bool>(false)),
+        timer_cb_([this, canceled{canceled_}](
+                      const boost::system::error_code &error) {
+          if (!error && !*canceled)
             onTimer();
         }),
         immediate_cb_([this] { onImmediate(); }) {
     assert(interval_ > 0 && interval_ <= 1000);
     timer_.async_wait(timer_cb_);
   }
 
+  AsioScheduler::~AsioScheduler() {
+    *canceled_ = true;
+    timer_.cancel();
+  };
+
   Scheduler::Ticks AsioScheduler::now() const {
     boost::posix_time::ptime t(boost::posix_time::microsec_clock::local_time());
     return (t - started_).total_milliseconds();