src/mc/explo/odpor/WakeupTree_test.cpp

   1 /* Copyright (c) 2017-2023. 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/3rd-party/catch.hpp"
   7 #include "src/mc/explo/odpor/Execution.hpp"
   8 #include "src/mc/explo/odpor/WakeupTree.hpp"
   9 #include "src/mc/explo/udpor/udpor_tests_private.hpp"
  10 #include "src/xbt/utils/iter/LazyPowerset.hpp"
  11
  12 using namespace simgrid::mc;
  13 using namespace simgrid::mc::odpor;
  14 using namespace simgrid::mc::udpor;
  15
  16 static void test_tree_iterator(const WakeupTree& tree, const std::vector<PartialExecution>& expected)
  17 {
  18   uint64_t num_nodes_traversed = 0;
  19   auto tree_iter               = tree.begin();
  20   for (auto expected_iter = expected.begin(); expected_iter != expected.end();
  21        ++expected_iter, ++tree_iter, ++num_nodes_traversed) {
  22     REQUIRE(tree_iter != tree.end());
  23     REQUIRE((*tree_iter)->get_sequence() == *expected_iter);
  24   }
  25   REQUIRE(num_nodes_traversed == tree.get_num_nodes());
  26 }
  27
  28 TEST_CASE("simgrid::mc::odpor::WakeupTree: Constructing Trees")
  29 {
  30   SECTION("Constructing empty trees")
  31   {
  32     WakeupTree tree;
  33     REQUIRE(tree.empty());
  34     REQUIRE(tree.get_num_entries() == 0);
  35     REQUIRE(tree.get_num_nodes() == 1);
  36     REQUIRE_FALSE(tree.get_min_single_process_node().has_value());
  37     REQUIRE_FALSE(tree.get_min_single_process_actor().has_value());
  38     test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{}});
  39   }
  40
  41   SECTION("Testing subtree creation and manipulation")
  42   {
  43     // Here, we make everything dependent. This will ensure that each unique sequence
  44     // inserted into the tree never "eventually looks like"
  45     const auto a0 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 1);
  46     const auto a1 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 2);
  47     const auto a2 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 3);
  48     const auto a3 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 4);
  49     const auto a4 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 5);
  50     const auto a5 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 6);
  51
  52     Execution execution;
  53     execution.push_transition(a0);
  54     execution.push_transition(a1);
  55     execution.push_transition(a2);
  56     execution.push_transition(a3);
  57     execution.push_transition(a4);
  58     execution.push_transition(a5);
  59
  60     // The tree is as follows:
  61     //                  {}
  62     //               /     /
  63     //             a1       a4
  64     //           /    /       /
  65     //          a2    a3       a1
  66     //         /     /   /      /
  67     //        a3    a2   a5     a2
  68     //       /     /             /
  69     //      a4    a4             a3
  70     //
  71     // Recall that new nodes (in this case the one with
  72     // action `a2`) are added such that they are "greater than" (under
  73     // the tree's `<` relation) all those that exist under the given parent
  74     WakeupTree tree;
  75     tree.insert(Execution(), {a1, a2, a3, a4});
  76     tree.insert(Execution(), {a1, a3, a2, a4});
  77     tree.insert(Execution(), {a1, a3, a2, a4, a5});
  78     tree.insert(Execution(), {a1, a3, a5});
  79     tree.insert(Execution(), {a4, a2, a1, a3});
  80     REQUIRE(tree.get_num_nodes() == 13);
  81     test_tree_iterator(tree, std::vector<PartialExecution>{
  82                                  PartialExecution{a1, a2, a3, a4}, PartialExecution{a1, a2, a3},
  83                                  PartialExecution{a1, a2}, PartialExecution{a1, a3, a2, a4},
  84                                  PartialExecution{a1, a3, a2}, PartialExecution{a1, a3, a5}, PartialExecution{a1, a3},
  85                                  PartialExecution{a1}, PartialExecution{a4, a2, a1, a3}, PartialExecution{a4, a2, a1},
  86                                  PartialExecution{a4, a2}, PartialExecution{a4}, PartialExecution{}});
  87
  88     SECTION("Cloning a tree from the root produces the same tree")
  89     {
  90       // The root node is the last node
  91       auto tree_root = tree.begin();
  92       std::advance(tree_root, tree.get_num_nodes() - 1);
  93
  94       WakeupTree clone = WakeupTree::make_subtree_rooted_at(*tree_root);
  95       REQUIRE(clone.empty() == tree.empty());
  96       REQUIRE(clone.get_num_entries() == tree.get_num_entries());
  97       REQUIRE(clone.get_num_nodes() == tree.get_num_nodes());
  98
  99       auto tree_iter = tree.begin();
 100       for (auto clone_iter = clone.begin(); clone_iter != clone.end(); ++clone_iter, ++tree_iter) {
 101         REQUIRE(tree_iter != tree.end());
 102         REQUIRE((*tree_iter)->get_sequence() == (*clone_iter)->get_sequence());
 103       }
 104     }
 105
 106     SECTION("Cloning a subtree from a leaf gives an empty tree")
 107     {
 108       // Let's pick the first leaf
 109       WakeupTree clone = WakeupTree::make_subtree_rooted_at(*tree.begin());
 110       REQUIRE(clone.empty());
 111       REQUIRE(clone.get_num_entries() == 0);
 112       REQUIRE(clone.get_num_nodes() == 1);
 113     }
 114
 115     SECTION("Cloning a subtree from an interior node gives the subtree underneath")
 116     {
 117       // Here, we pick the second-to-last node in the
 118       // series, which is the right-most child of the root
 119       auto right_most = tree.begin();
 120       std::advance(right_most, tree.get_num_nodes() - 2);
 121
 122       WakeupTree clone = WakeupTree::make_subtree_rooted_at(*right_most);
 123       REQUIRE_FALSE(clone.empty());
 124       REQUIRE(clone.get_num_entries() == 3);
 125       REQUIRE(clone.get_num_nodes() == 4);
 126       // Importantly, note that action `a4` is not included in
 127       // any of the executions; for in the subtree `clone` `a4`
 128       // is now the root.
 129       test_tree_iterator(clone, std::vector<PartialExecution>{PartialExecution{a2, a1, a3}, PartialExecution{a2, a1},
 130                                                               PartialExecution{a2}, PartialExecution{}});
 131     }
 132
 133     SECTION("Removing the first single-process subtree")
 134     {
 135       // Prior to removal, the first `a1` was the first single-process node
 136       REQUIRE(tree.get_min_single_process_node().has_value());
 137       REQUIRE(tree.get_min_single_process_actor().has_value());
 138       REQUIRE(tree.get_min_single_process_actor().value() == a1->aid_);
 139
 140       tree.remove_min_single_process_subtree();
 141
 142       // Now the first `a4` is
 143       REQUIRE(tree.get_min_single_process_node().has_value());
 144       REQUIRE(tree.get_min_single_process_actor().has_value());
 145       REQUIRE(tree.get_min_single_process_actor().value() == a4->aid_);
 146
 147       REQUIRE(tree.get_num_nodes() == 5);
 148       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a4, a2, a1, a3},
 149                                                              PartialExecution{a4, a2, a1}, PartialExecution{a4, a2},
 150                                                              PartialExecution{a4}, PartialExecution{}});
 151       tree.remove_min_single_process_subtree();
 152
 153       // At this point, we've removed each single-process subtree, so
 154       // the tree should be empty
 155       REQUIRE(tree.empty());
 156     }
 157   }
 158 }
 159
 160 TEST_CASE("simgrid::mc::odpor::WakeupTree: Testing Insertion for Empty Executions")
 161 {
 162   SECTION("Following an execution")
 163   {
 164     // We imagine the following completed execution `E`
 165     // consisting of executing actions a0-a3. Execution
 166     // `E` is the first such maximal execution explored
 167     // by ODPOR, which implies that a) all sleep sets are
 168     // empty and b) all wakeup trees (i.e. for each prefix) consist of the root
 169     // node with a single leaf containing the action
 170     // taken, save for the wakeup tree of the execution itself
 171     // which is empty.
 172
 173     // We first notice that there's a reversible race between
 174     // events 0 and 3.
 175
 176     const auto a0 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 3);
 177     const auto a1 = std::make_shared<IndependentAction>(Transition::Type::UNKNOWN, 4);
 178     const auto a2 = std::make_shared<ConditionallyDependentAction>(Transition::Type::UNKNOWN, 1);
 179     const auto a3 = std::make_shared<ConditionallyDependentAction>(Transition::Type::UNKNOWN, 4);
 180
 181     Execution execution;
 182     execution.push_transition(a0);
 183     execution.push_transition(a1);
 184     execution.push_transition(a2);
 185     execution.push_transition(a3);
 186
 187     REQUIRE(execution.get_racing_events_of(2) == std::unordered_set<Execution::EventHandle>{0});
 188     REQUIRE(execution.get_racing_events_of(3) == std::unordered_set<Execution::EventHandle>{0});
 189
 190     WakeupTree tree;
 191
 192     SECTION("Attempting to insert the empty sequence into an empty tree should have no effect")
 193     {
 194       tree.insert(Execution(), {});
 195       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{}});
 196     }
 197
 198     // First, we initialize the tree to how it looked prior
 199     // to the insertion of the race.
 200     tree.insert(Execution(), {a0});
 201
 202     // Then, after insertion, we ensure that the node was
 203     // indeed added to the tree.
 204     tree.insert(Execution(), {a1, a3});
 205     test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a1, a3},
 206                                                            PartialExecution{a1}, PartialExecution{}});
 207
 208     SECTION("Attempting to re-insert the same EXACT sequence should have no effect")
 209     {
 210       tree.insert(Execution(), {a1, a3});
 211       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a1, a3},
 212                                                              PartialExecution{a1}, PartialExecution{}});
 213     }
 214
 215     SECTION("Attempting to re-insert an equivalent sequence should have no effect")
 216     {
 217       // a3 and a1 are interchangeable since `a1` is independent with everything.
 218       // Since we found an equivalent sequence that is a leaf, nothing should result..
 219       tree.insert(Execution(), {a3, a1});
 220       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a1, a3},
 221                                                              PartialExecution{a1}, PartialExecution{}});
 222     }
 223
 224     SECTION("Attempting to insert the empty sequence should have no effect")
 225     {
 226       tree.insert(Execution(), {});
 227       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a1, a3},
 228                                                              PartialExecution{a1}, PartialExecution{}});
 229     }
 230
 231     SECTION("Inserting an extension should create a branch point")
 232     {
 233       // `a1.a2` shares the same `a1` prefix as `a1.a3`. Thus, the tree
 234       // should now look as follows:
 235       //
 236       //                 {}
 237       //               /    /
 238       //             a0     a1
 239       //                   /   /
 240       //                  a3   a2
 241       //
 242       // Recall that new nodes (in this case the one with
 243       // action `a2`) are added such that they are "greater than" (under
 244       // the tree's `<` relation) all those that exist under the given parent.
 245       tree.insert(Execution(), {a1, a2});
 246       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a1, a3},
 247                                                              PartialExecution{a1, a2}, PartialExecution{a1},
 248                                                              PartialExecution{}});
 249     }
 250   }
 251
 252   SECTION("Performing Arbitrary Insertions")
 253   {
 254     const auto a0 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 2);
 255     const auto a1 = std::make_shared<IndependentAction>(Transition::Type::UNKNOWN, 4);
 256     const auto a2 = std::make_shared<ConditionallyDependentAction>(Transition::Type::UNKNOWN, 3);
 257     const auto a3 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 1);
 258     const auto a4 = std::make_shared<IndependentAction>(Transition::Type::UNKNOWN, 2);
 259     const auto a5 = std::make_shared<ConditionallyDependentAction>(Transition::Type::UNKNOWN, 4);
 260     WakeupTree tree;
 261
 262     SECTION("Attempting to insert the empty sequence into an empty tree should have no effect")
 263     {
 264       tree.insert(Execution(), {});
 265       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{}});
 266     }
 267
 268     SECTION("Attempting to re-insert the same sequence multiple times should have no extra effect")
 269     {
 270       tree.insert(Execution(), {a4});
 271       tree.insert(Execution(), {a4});
 272       tree.insert(Execution(), {a4});
 273       REQUIRE(tree.get_num_nodes() == 2);
 274       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a4}, PartialExecution{}});
 275     }
 276
 277     SECTION("Attempting to insert an independent sequence same should have no extra effect")
 278     {
 279       // a4 and a1 are independent actions. Intuitively, then, we need only
 280       // search one ordering of the two actions. The wakeup tree handles
 281       // this by computing the `~` relation. The relation itself determines
 282       // whether the `a1` is an initial of `a3`, which it is not. It then
 283       // checks whether `a1` is independent with everything in the sequence
 284       // (in this case, consisting only of `a1`) which IS true. Since `a4`
 285       // is already a leaf node of the tree, it suffices to only have `a4`
 286       // in this tree to guide ODPOR.
 287       tree.insert(Execution(), {a4});
 288       tree.insert(Execution(), {a1});
 289       REQUIRE(tree.get_num_nodes() == 2);
 290       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a4}, PartialExecution{}});
 291     }
 292
 293     SECTION(
 294         "Attempting to insert a progression of executions should have no extra effect when the first process is a leaf")
 295     {
 296       // All progressions starting with `a0` are effectively already accounted
 297       // for by inserting `a0` since we `a0` "can always be made to look like"
 298       // (viz. the `~` relation) `a0.*` where `*` is some sequence of actions
 299       tree.insert(Execution(), {a0});
 300       tree.insert(Execution(), {a0, a3});
 301       tree.insert(Execution(), {a0, a3, a2});
 302       tree.insert(Execution(), {a0, a3, a2, a4});
 303       tree.insert(Execution(), {a0, a3, a2, a4});
 304       REQUIRE(tree.get_num_nodes() == 2);
 305       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{}});
 306     }
 307
 308     SECTION("Stress test with multiple branch points: `~_E` with different looking sequences")
 309     {
 310       // After the insertions below, the tree looks like the following:
 311       //                {}
 312       //              /    /
 313       //            a0     a2
 314       //                 /  |   /
 315       //               a0  a3   a5
 316       tree.insert(Execution(), {a0});
 317       tree.insert(Execution(), {a2, a0});
 318       tree.insert(Execution(), {a2, a3});
 319       tree.insert(Execution(), {a2, a5});
 320       REQUIRE(tree.get_num_nodes() == 6);
 321       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a2, a0},
 322                                                              PartialExecution{a2, a3}, PartialExecution{a2, a5},
 323                                                              PartialExecution{a2}, PartialExecution{}});
 324       SECTION("Adding more stress")
 325       {
 326         // In this case, `a2` and `a1` can be interchanged with each other.
 327         // Thus `a2.a1 == a1.a2`. Since there is already an interior node
 328         // containing `a2`, we attempt to add the what remains (viz. `a1`) to the
 329         // series. HOWEVER: we notice that `a2.a5` is "eventually equivalent to"
 330         // (that is `~` with) `a1.a2` since `a2` is an initial of the latter and
 331         // `a1` and `a5` are independent of each other.
 332         tree.insert(Execution(), {a1, a2});
 333         REQUIRE(tree.get_num_nodes() == 6);
 334         test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a2, a0},
 335                                                                PartialExecution{a2, a3}, PartialExecution{a2, a5},
 336                                                                PartialExecution{a2}, PartialExecution{}});
 337
 338         // With a3.a0, we notice that starting a sequence with `a3` is
 339         // always different than starting one with either `a0` or
 340         //
 341         // After the insertion, the tree looks like the following:
 342         //                     {}
 343         //              /     /        /
 344         //            a0     a2        a3
 345         //                 /  |  /     |
 346         //               a0  a3  a5    a0
 347         tree.insert(Execution(), {a3, a0});
 348         REQUIRE(tree.get_num_nodes() == 8);
 349         test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a2, a0},
 350                                                                PartialExecution{a2, a3}, PartialExecution{a2, a5},
 351                                                                PartialExecution{a2}, PartialExecution{a3, a0},
 352                                                                PartialExecution{a3}, PartialExecution{}});
 353       }
 354     }
 355   }
 356 }