src/mc/api/RemoteApp.cpp

   1 /* Copyright (c) 2015-2023. 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/api/RemoteApp.hpp"
   7 #include "src/mc/explo/Exploration.hpp"
   8 #include "src/mc/mc_config.hpp"
   9 #include "xbt/asserts.h"
  10 #include "src/mc/api/State.hpp"
  11 #include "src/mc/mc_config.hpp"
  12 #include "src/mc/mc_exit.hpp"
  13 #include "src/mc/mc_private.hpp"
  14 #include "xbt/log.h"
  15 #include "xbt/system_error.hpp"
  16 #include <signal.h>
  17
  18 #include <algorithm>
  19 #include <array>
  20 #include <memory>
  21 #include <numeric>
  22 #include <string>
  23
  24 #include <sys/ptrace.h>
  25 #include <sys/wait.h>
  26
  27 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_Session, mc, "Model-checker session");
  28 XBT_LOG_EXTERNAL_CATEGORY(mc_global);
  29
  30 namespace simgrid::mc {
  31
  32 RemoteApp::RemoteApp(const std::vector<char*>& args, bool need_memory_introspection)
  33 {
  34   for (auto* arg : args)
  35     app_args_.push_back(arg);
  36
  37   checker_side_ = std::make_unique<simgrid::mc::CheckerSide>(app_args_, need_memory_introspection);
  38
  39   if (need_memory_introspection)
  40     initial_snapshot_ = std::make_shared<simgrid::mc::Snapshot>(0, page_store_, *checker_side_->get_remote_memory());
  41 }
  42
  43 RemoteApp::~RemoteApp()
  44 {
  45   initial_snapshot_ = nullptr;
  46   checker_side_     = nullptr;
  47 }
  48
  49 void RemoteApp::restore_initial_state()
  50 {
  51   if (initial_snapshot_ == nullptr) { // No memory introspection
  52     // We need to destroy the existing CheckerSide before creating the new one, or libevent gets crazy
  53     checker_side_.reset(nullptr);
  54     checker_side_.reset(new simgrid::mc::CheckerSide(app_args_, true));
  55   } else
  56     initial_snapshot_->restore(*checker_side_->get_remote_memory());
  57 }
  58
  59 unsigned long RemoteApp::get_maxpid() const
  60 {
  61   // note: we could maybe cache it and count the actor creation on checker side too.
  62   // But counting correctly accross state checkpoint/restore would be annoying.
  63
  64   checker_side_->get_channel().send(MessageType::ACTORS_MAXPID);
  65   s_mc_message_int_t answer;
  66   ssize_t answer_size = checker_side_->get_channel().receive(answer);
  67   xbt_assert(answer_size != -1, "Could not receive message");
  68   xbt_assert(answer_size == sizeof answer, "Broken message (size=%zd; expected %zu)", answer_size, sizeof answer);
  69   xbt_assert(answer.type == MessageType::ACTORS_MAXPID_REPLY,
  70              "Received unexpected message %s (%i); expected MessageType::ACTORS_MAXPID_REPLY (%i)",
  71              to_c_str(answer.type), (int)answer.type, (int)MessageType::ACTORS_MAXPID_REPLY);
  72
  73   return answer.value;
  74 }
  75
  76 void RemoteApp::get_actors_status(std::map<aid_t, ActorState>& whereto) const
  77 {
  78   // The messaging happens as follows:
  79   //
  80   // CheckerSide                  AppSide
  81   // send ACTORS_STATUS ---->
  82   //                    <----- send ACTORS_STATUS_REPLY
  83   //                    <----- send `N` `s_mc_message_actors_status_one_t` structs
  84   //                    <----- send `M` `s_mc_message_simcall_probe_one_t` structs
  85   checker_side_->get_channel().send(MessageType::ACTORS_STATUS);
  86
  87   s_mc_message_actors_status_answer_t answer;
  88   ssize_t answer_size = checker_side_->get_channel().receive(answer);
  89   xbt_assert(answer_size != -1, "Could not receive message");
  90   xbt_assert(answer_size == sizeof answer, "Broken message (size=%zd; expected %zu)", answer_size, sizeof answer);
  91   xbt_assert(answer.type == MessageType::ACTORS_STATUS_REPLY,
  92              "Received unexpected message %s (%i); expected MessageType::ACTORS_STATUS_REPLY (%i)",
  93              to_c_str(answer.type), (int)answer.type, (int)MessageType::ACTORS_STATUS_REPLY);
  94
  95   // Message sanity checks
  96   xbt_assert(answer.count >= 0, "Received an ACTOR_STATUS_REPLY message with an actor count of '%d' < 0", answer.count);
  97   xbt_assert(answer.transition_count >= 0, "Received an ACTOR_STATUS_REPLY message with transition_count '%d' < 0",
  98              answer.transition_count);
  99   xbt_assert(answer.transition_count == 0 || answer.count >= 0,
 100              "Received an ACTOR_STATUS_REPLY message with no actor data "
 101              "but with transition data nonetheless");
 102
 103   std::vector<s_mc_message_actors_status_one_t> status(answer.count);
 104   if (answer.count > 0) {
 105     size_t size      = status.size() * sizeof(s_mc_message_actors_status_one_t);
 106     ssize_t received = checker_side_->get_channel().receive(status.data(), size);
 107     xbt_assert(static_cast<size_t>(received) == size);
 108   }
 109
 110   // Ensures that each actor sends precisely `answer.transition_count` transitions. While technically
 111   // this doesn't catch the edge case where actor A sends 3 instead of 2 and actor B sends 2 instead
 112   // of 3 transitions, that is ignored here since that invariant needs to be enforced on the AppSide
 113   const auto expected_transitions = std::accumulate(
 114       status.begin(), status.end(), 0, [](int total, const auto& actor) { return total + actor.n_transitions; });
 115   xbt_assert(expected_transitions == answer.transition_count,
 116              "Expected to receive %d transition(s) but was only notified of %d by the app side", expected_transitions,
 117              answer.transition_count);
 118
 119   whereto.clear();
 120
 121   for (const auto& actor : status) {
 122     xbt_assert(actor.n_transitions == 0 || actor.n_transitions == actor.max_considered,
 123                "If any transitions are serialized for an actor, it must match the "
 124                "total number of transitions that can be considered for the actor "
 125                "(currently %d), but only %d transition(s) was/were said to be encoded",
 126                actor.max_considered, actor.n_transitions);
 127
 128     std::vector<std::shared_ptr<Transition>> actor_transitions;
 129     for (int times_considered = 0; times_considered < actor.n_transitions; times_considered++) {
 130       s_mc_message_simcall_probe_one_t probe;
 131       ssize_t received = checker_side_->get_channel().receive(probe);
 132       xbt_assert(received >= 0, "Could not receive response to ACTORS_PROBE message (%s)", strerror(errno));
 133       xbt_assert(static_cast<size_t>(received) == sizeof probe,
 134                  "Could not receive response to ACTORS_PROBE message (%zd bytes received != %zu bytes expected",
 135                  received, sizeof probe);
 136
 137       std::stringstream stream(probe.buffer.data());
 138       actor_transitions.emplace_back(deserialize_transition(actor.aid, times_considered, stream));
 139     }
 140
 141     XBT_DEBUG("Received %zu transitions for actor %ld", actor_transitions.size(), actor.aid);
 142     whereto.try_emplace(actor.aid, actor.aid, actor.enabled, actor.max_considered, std::move(actor_transitions));
 143   }
 144 }
 145
 146 void RemoteApp::check_deadlock() const
 147 {
 148   xbt_assert(checker_side_->get_channel().send(MessageType::DEADLOCK_CHECK) == 0, "Could not check deadlock state");
 149   s_mc_message_int_t message;
 150   ssize_t received = checker_side_->get_channel().receive(message);
 151   xbt_assert(received != -1, "Could not receive message");
 152   xbt_assert(received == sizeof message, "Broken message (size=%zd; expected %zu)", received, sizeof message);
 153   xbt_assert(message.type == MessageType::DEADLOCK_CHECK_REPLY,
 154              "Received unexpected message %s (%i); expected MessageType::DEADLOCK_CHECK_REPLY (%i)",
 155              to_c_str(message.type), (int)message.type, (int)MessageType::DEADLOCK_CHECK_REPLY);
 156
 157   if (message.value != 0) {
 158     auto* explo = Exploration::get_instance();
 159     XBT_CINFO(mc_global, "Counter-example execution trace:");
 160     for (auto const& frame : explo->get_textual_trace())
 161       XBT_CINFO(mc_global, "  %s", frame.c_str());
 162     XBT_INFO("You can debug the problem (and see the whole details) by rerunning out of simgrid-mc with "
 163              "--cfg=model-check/replay:'%s'",
 164              explo->get_record_trace().to_string().c_str());
 165     explo->log_state();
 166     throw DeadlockError();
 167   }
 168 }
 169
 170 void RemoteApp::wait_for_requests()
 171 {
 172   checker_side_->wait_for_requests();
 173 }
 174
 175 Transition* RemoteApp::handle_simcall(aid_t aid, int times_considered, bool new_transition)
 176 {
 177   s_mc_message_simcall_execute_t m = {};
 178   m.type                           = MessageType::SIMCALL_EXECUTE;
 179   m.aid_                           = aid;
 180   m.times_considered_              = times_considered;
 181   checker_side_->get_channel().send(m);
 182
 183   if (auto* memory = get_remote_process_memory(); memory != nullptr)
 184     memory->clear_cache();
 185   if (checker_side_->running())
 186     checker_side_->dispatch_events(); // The app may send messages while processing the transition
 187
 188   s_mc_message_simcall_execute_answer_t answer;
 189   ssize_t s = checker_side_->get_channel().receive(answer);
 190   xbt_assert(s != -1, "Could not receive message");
 191   xbt_assert(s == sizeof answer, "Broken message (size=%zd; expected %zu)", s, sizeof answer);
 192   xbt_assert(answer.type == MessageType::SIMCALL_EXECUTE_ANSWER,
 193              "Received unexpected message %s (%i); expected MessageType::SIMCALL_EXECUTE_ANSWER (%i)",
 194              to_c_str(answer.type), (int)answer.type, (int)MessageType::SIMCALL_EXECUTE_ANSWER);
 195
 196   if (new_transition) {
 197     std::stringstream stream(answer.buffer.data());
 198     return deserialize_transition(aid, times_considered, stream);
 199   } else
 200     return nullptr;
 201 }
 202
 203 void RemoteApp::finalize_app(bool terminate_asap)
 204 {
 205   checker_side_->finalize(terminate_asap);
 206 }
 207
 208 } // namespace simgrid::mc