src/mc/VisitedState.cpp

   1 /* Copyright (c) 2011-2023. The SimGrid Team. All rights reserved.          */
   2
   3 /* This program is free software; you can redistribute it and/or modify it
   4  * under the terms of the license (GNU LGPL) which comes with this package. */
   5
   6 #include "src/mc/VisitedState.hpp"
   7 #include "src/mc/explo/Exploration.hpp"
   8 #include "src/mc/mc_config.hpp"
   9 #include "src/mc/mc_private.hpp"
  10
  11 #include <unistd.h>
  12 #include <sys/wait.h>
  13 #include <memory>
  14 #include <boost/range/algorithm.hpp>
  15
  16 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_VisitedState, mc, "Logging specific to state equality detection mechanisms");
  17
  18 namespace simgrid::mc {
  19
  20 /** @brief Save the current state */
  21 VisitedState::VisitedState(unsigned long state_number, unsigned int actor_count, RemoteApp& remote_app)
  22     : heap_bytes_used_(remote_app.get_remote_process_memory()->get_remote_heap_bytes())
  23     , actor_count_(actor_count)
  24     , num_(state_number)
  25 {
  26   this->system_state_ = std::make_shared<simgrid::mc::Snapshot>(state_number, remote_app.get_page_store(),
  27                                                                 *remote_app.get_remote_process_memory());
  28 }
  29
  30 void VisitedStates::prune()
  31 {
  32   while (states_.size() > (std::size_t)_sg_mc_max_visited_states) {
  33     XBT_DEBUG("Try to remove visited state (maximum number of stored states reached)");
  34     auto min_element = boost::range::min_element(
  35         states_, [](const std::unique_ptr<simgrid::mc::VisitedState>& a,
  36                     const std::unique_ptr<simgrid::mc::VisitedState>& b) { return a->num_ < b->num_; });
  37     xbt_assert(min_element != states_.end());
  38     // and drop it:
  39     states_.erase(min_element);
  40     XBT_DEBUG("Remove visited state (maximum number of stored states reached)");
  41   }
  42 }
  43
  44 /** @brief Checks whether a given state has already been visited by the algorithm. */
  45 std::unique_ptr<simgrid::mc::VisitedState>
  46 VisitedStates::addVisitedState(unsigned long state_number, simgrid::mc::State* graph_state, RemoteApp& remote_app)
  47 {
  48   auto new_state =
  49       std::make_unique<simgrid::mc::VisitedState>(state_number, graph_state->get_actor_count(), remote_app);
  50
  51   graph_state->set_system_state(new_state->system_state_);
  52   XBT_DEBUG("Snapshot %p of visited state %ld (exploration stack state %ld)", new_state->system_state_.get(),
  53             new_state->num_, graph_state->get_num());
  54
  55   auto [range_begin, range_end] = boost::range::equal_range(states_, new_state.get(), [](auto const& a, auto const& b) {
  56     return std::make_pair(a->actor_count_, a->heap_bytes_used_) < std::make_pair(b->actor_count_, b->heap_bytes_used_);
  57   });
  58
  59   for (auto i = range_begin; i != range_end; ++i) {
  60     auto& visited_state = *i;
  61     if (visited_state->system_state_->equals_to(*new_state->system_state_.get(),
  62                                                 *remote_app.get_remote_process_memory())) {
  63       // The state has been visited:
  64
  65       std::unique_ptr<simgrid::mc::VisitedState> old_state = std::move(visited_state);
  66
  67       if (old_state->original_num_ == -1) // I'm the copy of an original process
  68         new_state->original_num_ = old_state->num_;
  69       else // I'm the copy of a copy
  70         new_state->original_num_ = old_state->original_num_;
  71
  72       XBT_DEBUG("State %ld already visited ! (equal to state %ld (state %ld in dot_output))", new_state->num_,
  73                 old_state->num_, new_state->original_num_);
  74
  75       /* Replace the old state with the new one (with a bigger num)
  76           (when the max number of visited states is reached,  the oldest
  77           one is removed according to its number (= with the min number) */
  78       XBT_DEBUG("Replace visited state %ld with the new visited state %ld", old_state->num_, new_state->num_);
  79
  80       visited_state = std::move(new_state);
  81       return old_state;
  82     }
  83   }
  84
  85   XBT_DEBUG("Insert new visited state %ld (total : %lu)", new_state->num_, (unsigned long)states_.size());
  86   states_.insert(range_begin, std::move(new_state));
  87   this->prune();
  88   return nullptr;
  89 }
  90
  91 } // namespace simgrid::mc