don't start the platform timer when applying a block

Author: spoonincode

libraries/chain/include/eosio/chain/platform_timer.hpp

@@ -13,13 +13,19 @@ struct platform_timer {
    platform_timer();
    ~platform_timer();
 
+   //start() & stop() are not thread safe to each other; i.e. do not overlap calls to start() and stop()
    void start(fc::time_point tp);
    void stop();
+   //interrupt_timer() can be called from any thread
    void interrupt_timer();
 
-   /* Sets a callback for when timer expires. Be aware this could might fire from a signal handling context and/or
+   /* Sets a callback for when timer expires. Be aware this could fire from a signal handling context and/or
       on any particular thread. Only a single callback can be registered at once; trying to register more will
-      result in an exception. Setting to nullptr disables any current set callback */
+      result in an exception. Setting to nullptr disables any current set callback.
+      Also, stop() is not perfectly synchronized with the callback. It is possible for stop() to return and the
+      callback still execute if the timer expires and stop() is called nearly simultaneously.
+      However, set_expiration_callback() is synchronized with the callback.
+   */
    void set_expiration_callback(void(*func)(void*), void* user) {
       bool expect_false = false;
       while(!atomic_compare_exchange_strong(&_callback_variables_busy, &expect_false, true))
@@ -45,6 +51,7 @@ struct platform_timer {
    void expire_now();
 
    std::atomic<state_t> _state = state_t::stopped;
+   bool timer_running_forever = false;
 
    struct impl;
    constexpr static size_t fwd_size = 8;

libraries/chain/platform_timer_asio_fallback.cpp

@@ -56,11 +56,14 @@ platform_timer::~platform_timer() {
 }
 
 void platform_timer::start(fc::time_point tp) {
+   assert(_state == state_t::stopped);
    if(tp == fc::time_point::maximum()) {
       _state = state_t::running;
+      timer_running_forever = true;
       return;
    }
    fc::microseconds x = tp.time_since_epoch() - fc::time_point::now().time_since_epoch();
+   timer_running_forever = false;
    if(x.count() <= 0)
       _state = state_t::timed_out;
    else {
@@ -89,11 +92,14 @@ void platform_timer::interrupt_timer() {
 }
 
 void platform_timer::stop() {
-   if(_state == state_t::stopped)
+   const state_t prior_state = _state;
+   if(prior_state == state_t::stopped)
+      return;
+   _state = state_t::stopped;
+   if(prior_state == state_t::timed_out || timer_running_forever)
       return;
 
    my->timer->cancel();
-   _state = state_t::stopped;
 }
 
 }}

libraries/chain/platform_timer_kqueue.cpp

@@ -88,20 +88,23 @@ platform_timer::~platform_timer() {
 }
 
 void platform_timer::start(fc::time_point tp) {
+   assert(_state == state_t::stopped);
    if(tp == fc::time_point::maximum()) {
-      expired = false;
+      _state = state_t::running;
+      timer_running_forever = true;
       return;
    }
    fc::microseconds x = tp.time_since_epoch() - fc::time_point::now().time_since_epoch();
+   timer_running_forever = false;
    if(x.count() <= 0)
-      expired = true;
+      _state = state_t::timed_out;
    else {
       struct kevent64_s aTimerEvent;
       EV_SET64(&aTimerEvent, my->timerid, EVFILT_TIMER, EV_ADD|EV_ENABLE|EV_ONESHOT, NOTE_USECONDS|NOTE_CRITICAL, x.count(), (uint64_t)this, 0, 0);
 
-      expired = false;
+      _state = state_t::running;
       if(kevent64(kqueue_fd, &aTimerEvent, 1, NULL, 0, KEVENT_FLAG_IMMEDIATE, NULL) != 0)
-         expired = true;
+         _state = state_t::timed_out;
    }
 }
 
@@ -120,7 +123,11 @@ void platform_timer::interrupt_timer() {
 }
 
 void platform_timer::stop() {
-   if(_state == state_t::stopped)
+   const state_t prior_state = _state;
+   if(prior_state == state_t::stopped)
+      return;
+   _state = state_t::stopped;
+   if(prior_state == state_t::timed_out || timer_running_forever)
       return;
 
    struct kevent64_s stop_timer_event;

libraries/chain/platform_timer_posix.cpp

@@ -58,9 +58,11 @@ void platform_timer::start(fc::time_point tp) {
    assert(_state == state_t::stopped);
    if(tp == fc::time_point::maximum()) {
       _state = state_t::running;
+      timer_running_forever = true;
       return;
    }
    fc::microseconds x = tp.time_since_epoch() - fc::time_point::now().time_since_epoch();
+   timer_running_forever = false;
    if(x.count() <= 0)
       _state = state_t::timed_out;
    else {
@@ -88,11 +90,14 @@ void platform_timer::interrupt_timer() {
 }
 
 void platform_timer::stop() {
-   if(_state == state_t::stopped)
+   const state_t prior_state = _state;
+   if(prior_state == state_t::stopped)
+      return;
+   _state = state_t::stopped;
+   if(prior_state == state_t::timed_out || timer_running_forever)
       return;
    struct itimerspec disable = {{0, 0}, {0, 0}};
    timer_settime(my->timerid, 0, &disable, NULL);
-   _state = state_t::stopped;
 }
 
 }

libraries/chain/transaction_context.cpp

@@ -111,7 +111,8 @@ namespace eosio::chain {
       init_net_usage = initial_net_usage;
 
       // set maximum to a semi-valid deadline to allow for pause math and conversion to dates for logging
-      if( block_deadline == fc::time_point::maximum() ) block_deadline = start + fc::hours(24*7*52);
+      const fc::time_point far_future_time = start + fc::days(7*52);
+      if( block_deadline == fc::time_point::maximum() ) block_deadline = far_future_time;
 
       const auto& cfg = control.get_global_properties().configuration;
       auto& rl = control.get_mutable_resource_limits_manager();
@@ -250,7 +251,10 @@ namespace eosio::chain {
          _deadline = block_deadline;
       }
 
-      transaction_timer.start( _deadline );
+      if(_deadline < far_future_time)
+         transaction_timer.start( _deadline );
+      else
+         transaction_timer.start( fc::time_point::maximum() );  //avoids overhead in starting the timer at all
       checktime(); // Fail early if deadline has already been exceeded
       is_initialized = true;
    }