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 static void test_tree_empty(const WakeupTree& tree)
  29 {
  30   REQUIRE(tree.empty());
  31   REQUIRE(tree.get_num_entries() == 0);
  32   REQUIRE(tree.get_num_nodes() == 1);
  33   REQUIRE_FALSE(tree.get_min_single_process_node().has_value());
  34   REQUIRE_FALSE(tree.get_min_single_process_actor().has_value());
  35   test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{}});
  36 }
  37
  38 TEST_CASE("simgrid::mc::odpor::WakeupTree: Constructing Trees")
  39 {
  40   SECTION("Constructing empty trees")
  41   {
  42     test_tree_empty(WakeupTree());
  43   }
  44
  45   SECTION("Testing subtree creation and manipulation")
  46   {
  47     // Here, we make everything dependent. This will ensure that each unique sequence
  48     // inserted into the tree never "eventually looks like"
  49     const auto a0 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 1);
  50     const auto a1 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 2);
  51     const auto a2 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 3);
  52     const auto a3 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 4);
  53     const auto a4 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 5);
  54     const auto a5 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 6);
  55
  56     Execution execution;
  57     execution.push_transition(a0);
  58     execution.push_transition(a1);
  59     execution.push_transition(a2);
  60     execution.push_transition(a3);
  61     execution.push_transition(a4);
  62     execution.push_transition(a5);
  63
  64     // The tree is as follows:
  65     //                  {}
  66     //               /     /
  67     //             a1       a4
  68     //           /    /       /
  69     //          a2    a3       a1
  70     //         /     /   /      /
  71     //        a3    a2   a5     a2
  72     //       /     /             /
  73     //      a4    a4             a3
  74     //
  75     // Recall that new nodes (in this case the one with
  76     // action `a2`) are added such that they are "greater than" (under
  77     // the tree's `<` relation) all those that exist under the given parent
  78     WakeupTree tree;
  79     tree.insert(Execution(), {a1, a2, a3, a4});
  80     tree.insert(Execution(), {a1, a3, a2, a4});
  81     tree.insert(Execution(), {a1, a3, a2, a4, a5});
  82     tree.insert(Execution(), {a1, a3, a5});
  83     tree.insert(Execution(), {a4, a2, a1, a3});
  84     REQUIRE(tree.get_num_nodes() == 13);
  85     test_tree_iterator(tree, std::vector<PartialExecution>{
  86                                  PartialExecution{a1, a2, a3, a4}, PartialExecution{a1, a2, a3},
  87                                  PartialExecution{a1, a2}, PartialExecution{a1, a3, a2, a4},
  88                                  PartialExecution{a1, a3, a2}, PartialExecution{a1, a3, a5}, PartialExecution{a1, a3},
  89                                  PartialExecution{a1}, PartialExecution{a4, a2, a1, a3}, PartialExecution{a4, a2, a1},
  90                                  PartialExecution{a4, a2}, PartialExecution{a4}, PartialExecution{}});
  91
  92     SECTION("Cloning a tree from the root produces the same tree")
  93     {
  94       // The root node is the last node
  95       auto tree_root = tree.begin();
  96       std::advance(tree_root, tree.get_num_nodes() - 1);
  97
  98       WakeupTree clone = WakeupTree::make_subtree_rooted_at(*tree_root);
  99       REQUIRE(clone.empty() == tree.empty());
 100       REQUIRE(clone.get_num_entries() == tree.get_num_entries());
 101       REQUIRE(clone.get_num_nodes() == tree.get_num_nodes());
 102
 103       auto tree_iter = tree.begin();
 104       for (auto clone_iter = clone.begin(); clone_iter != clone.end(); ++clone_iter, ++tree_iter) {
 105         REQUIRE(tree_iter != tree.end());
 106         REQUIRE((*tree_iter)->get_sequence() == (*clone_iter)->get_sequence());
 107       }
 108     }
 109
 110     SECTION("Cloning a subtree from a leaf gives an empty tree")
 111     {
 112       // Let's pick the first leaf
 113       WakeupTree clone = WakeupTree::make_subtree_rooted_at(*tree.begin());
 114       REQUIRE(clone.empty());
 115       REQUIRE(clone.get_num_entries() == 0);
 116       REQUIRE(clone.get_num_nodes() == 1);
 117     }
 118
 119     SECTION("Cloning a subtree from an interior node gives the subtree underneath")
 120     {
 121       // Here, we pick the second-to-last node in the
 122       // series, which is the right-most child of the root
 123       auto right_most = tree.begin();
 124       std::advance(right_most, tree.get_num_nodes() - 2);
 125
 126       WakeupTree clone = WakeupTree::make_subtree_rooted_at(*right_most);
 127       REQUIRE_FALSE(clone.empty());
 128       REQUIRE(clone.get_num_entries() == 3);
 129       REQUIRE(clone.get_num_nodes() == 4);
 130       // Importantly, note that action `a4` is not included in
 131       // any of the executions; for in the subtree `clone` `a4`
 132       // is now the root.
 133       test_tree_iterator(clone, std::vector<PartialExecution>{PartialExecution{a2, a1, a3}, PartialExecution{a2, a1},
 134                                                               PartialExecution{a2}, PartialExecution{}});
 135     }
 136
 137     SECTION("Removing the first single-process subtree")
 138     {
 139       // Prior to removal, the first `a1` was the first single-process node
 140       REQUIRE(tree.get_min_single_process_node().has_value());
 141       REQUIRE(tree.get_min_single_process_actor().has_value());
 142       REQUIRE(tree.get_min_single_process_actor().value() == a1->aid_);
 143
 144       tree.remove_min_single_process_subtree();
 145
 146       // Now the first `a4` is
 147       REQUIRE(tree.get_min_single_process_node().has_value());
 148       REQUIRE(tree.get_min_single_process_actor().has_value());
 149       REQUIRE(tree.get_min_single_process_actor().value() == a4->aid_);
 150
 151       REQUIRE(tree.get_num_nodes() == 5);
 152       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a4, a2, a1, a3},
 153                                                              PartialExecution{a4, a2, a1}, PartialExecution{a4, a2},
 154                                                              PartialExecution{a4}, PartialExecution{}});
 155       tree.remove_min_single_process_subtree();
 156
 157       // At this point, we've removed each single-process subtree, so
 158       // the tree should be empty
 159       REQUIRE(tree.empty());
 160     }
 161
 162     SECTION("Removing the first single-process subtree from an empty tree has no effect")
 163     {
 164       WakeupTree empty_tree;
 165       test_tree_empty(empty_tree);
 166
 167       empty_tree.remove_min_single_process_subtree();
 168
 169       // There should be no effect: the tree should still be empty
 170       // and the function should have no effect
 171       test_tree_empty(empty_tree);
 172     }
 173   }
 174 }
 175
 176 TEST_CASE("simgrid::mc::odpor::WakeupTree: Testing Insertion for Empty Executions")
 177 {
 178   SECTION("Following an execution")
 179   {
 180     // We imagine the following completed execution `E`
 181     // consisting of executing actions a0-a3. Execution
 182     // `E` is the first such maximal execution explored
 183     // by ODPOR, which implies that a) all sleep sets are
 184     // empty and b) all wakeup trees (i.e. for each prefix) consist of the root
 185     // node with a single leaf containing the action
 186     // taken, save for the wakeup tree of the execution itself
 187     // which is empty.
 188
 189     // We first notice that there's a reversible race between
 190     // events 0 and 3.
 191
 192     const auto a0 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 3);
 193     const auto a1 = std::make_shared<IndependentAction>(Transition::Type::UNKNOWN, 4);
 194     const auto a2 = std::make_shared<ConditionallyDependentAction>(Transition::Type::UNKNOWN, 1);
 195     const auto a3 = std::make_shared<ConditionallyDependentAction>(Transition::Type::UNKNOWN, 4);
 196
 197     Execution execution;
 198     execution.push_transition(a0);
 199     execution.push_transition(a1);
 200     execution.push_transition(a2);
 201     execution.push_transition(a3);
 202
 203     REQUIRE(execution.get_racing_events_of(2) == std::unordered_set<Execution::EventHandle>{0});
 204     REQUIRE(execution.get_racing_events_of(3) == std::unordered_set<Execution::EventHandle>{0});
 205
 206     WakeupTree tree;
 207
 208     SECTION("Attempting to insert the empty sequence into an empty tree should have no effect")
 209     {
 210       tree.insert(Execution(), {});
 211       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{}});
 212     }
 213
 214     // First, we initialize the tree to how it looked prior
 215     // to the insertion of the race.
 216     tree.insert(Execution(), {a0});
 217
 218     // Then, after insertion, we ensure that the node was
 219     // indeed added to the tree.
 220     tree.insert(Execution(), {a1, a3});
 221     test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a1, a3},
 222                                                            PartialExecution{a1}, PartialExecution{}});
 223
 224     SECTION("Attempting to re-insert the same EXACT sequence should have no effect")
 225     {
 226       tree.insert(Execution(), {a1, a3});
 227       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a1, a3},
 228                                                              PartialExecution{a1}, PartialExecution{}});
 229     }
 230
 231     SECTION("Attempting to re-insert an equivalent sequence should have no effect")
 232     {
 233       // a3 and a1 are interchangeable since `a1` is independent with everything.
 234       // Since we found an equivalent sequence that is a leaf, nothing should result..
 235       tree.insert(Execution(), {a3, a1});
 236       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a1, a3},
 237                                                              PartialExecution{a1}, PartialExecution{}});
 238     }
 239
 240     SECTION("Attempting to insert the empty sequence should have no effect")
 241     {
 242       tree.insert(Execution(), {});
 243       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a1, a3},
 244                                                              PartialExecution{a1}, PartialExecution{}});
 245     }
 246
 247     SECTION("Inserting an extension should create a branch point")
 248     {
 249       // `a1.a2` shares the same `a1` prefix as `a1.a3`. Thus, the tree
 250       // should now look as follows:
 251       //
 252       //                 {}
 253       //               /    /
 254       //             a0     a1
 255       //                   /   /
 256       //                  a3   a2
 257       //
 258       // Recall that new nodes (in this case the one with
 259       // action `a2`) are added such that they are "greater than" (under
 260       // the tree's `<` relation) all those that exist under the given parent.
 261       tree.insert(Execution(), {a1, a2});
 262       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a1, a3},
 263                                                              PartialExecution{a1, a2}, PartialExecution{a1},
 264                                                              PartialExecution{}});
 265     }
 266   }
 267
 268   SECTION("Performing Arbitrary Insertions")
 269   {
 270     const auto a0 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 2);
 271     const auto a1 = std::make_shared<IndependentAction>(Transition::Type::UNKNOWN, 4);
 272     const auto a2 = std::make_shared<ConditionallyDependentAction>(Transition::Type::UNKNOWN, 3);
 273     const auto a3 = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 1);
 274     const auto a4 = std::make_shared<IndependentAction>(Transition::Type::UNKNOWN, 2);
 275     const auto a5 = std::make_shared<ConditionallyDependentAction>(Transition::Type::UNKNOWN, 4);
 276     WakeupTree tree;
 277
 278     SECTION("Attempting to insert the empty sequence into an empty tree should have no effect")
 279     {
 280       tree.insert(Execution(), {});
 281       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{}});
 282     }
 283
 284     SECTION("Attempting to re-insert the same sequence multiple times should have no extra effect")
 285     {
 286       tree.insert(Execution(), {a4});
 287       tree.insert(Execution(), {a4});
 288       tree.insert(Execution(), {a4});
 289       REQUIRE(tree.get_num_nodes() == 2);
 290       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a4}, PartialExecution{}});
 291     }
 292
 293     SECTION("Attempting to insert an independent sequence same should have no extra effect")
 294     {
 295       // a4 and a1 are independent actions. Intuitively, then, we need only
 296       // search one ordering of the two actions. The wakeup tree handles
 297       // this by computing the `~` relation. The relation itself determines
 298       // whether the `a1` is an initial of `a3`, which it is not. It then
 299       // checks whether `a1` is independent with everything in the sequence
 300       // (in this case, consisting only of `a1`) which IS true. Since `a4`
 301       // is already a leaf node of the tree, it suffices to only have `a4`
 302       // in this tree to guide ODPOR.
 303       tree.insert(Execution(), {a4});
 304       tree.insert(Execution(), {a1});
 305       REQUIRE(tree.get_num_nodes() == 2);
 306       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a4}, PartialExecution{}});
 307     }
 308
 309     SECTION(
 310         "Attempting to insert a progression of executions should have no extra effect when the first process is a leaf")
 311     {
 312       // All progressions starting with `a0` are effectively already accounted
 313       // for by inserting `a0` since we `a0` "can always be made to look like"
 314       // (viz. the `~` relation) `a0.*` where `*` is some sequence of actions
 315       tree.insert(Execution(), {a0});
 316       tree.insert(Execution(), {a0, a3});
 317       tree.insert(Execution(), {a0, a3, a2});
 318       tree.insert(Execution(), {a0, a3, a2, a4});
 319       tree.insert(Execution(), {a0, a3, a2, a4});
 320       REQUIRE(tree.get_num_nodes() == 2);
 321       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{}});
 322     }
 323
 324     SECTION("Stress test with multiple branch points: `~_E` with different looking sequences")
 325     {
 326       // After the insertions below, the tree looks like the following:
 327       //                {}
 328       //              /    /
 329       //            a0     a2
 330       //                 /  |   /
 331       //               a0  a3   a5
 332       tree.insert(Execution(), {a0});
 333       tree.insert(Execution(), {a2, a0});
 334       tree.insert(Execution(), {a2, a3});
 335       tree.insert(Execution(), {a2, a5});
 336       REQUIRE(tree.get_num_nodes() == 6);
 337       test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a2, a0},
 338                                                              PartialExecution{a2, a3}, PartialExecution{a2, a5},
 339                                                              PartialExecution{a2}, PartialExecution{}});
 340       SECTION("Adding more stress")
 341       {
 342         // In this case, `a2` and `a1` can be interchanged with each other.
 343         // Thus `a2.a1 == a1.a2`. Since there is already an interior node
 344         // containing `a2`, we attempt to add the what remains (viz. `a1`) to the
 345         // series. HOWEVER: we notice that `a2.a5` is "eventually equivalent to"
 346         // (that is `~` with) `a1.a2` since `a2` is an initial of the latter and
 347         // `a1` and `a5` are independent of each other.
 348         tree.insert(Execution(), {a1, a2});
 349         REQUIRE(tree.get_num_nodes() == 6);
 350         test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a2, a0},
 351                                                                PartialExecution{a2, a3}, PartialExecution{a2, a5},
 352                                                                PartialExecution{a2}, PartialExecution{}});
 353
 354         // With a3.a0, we notice that starting a sequence with `a3` is
 355         // always different than starting one with either `a0` or
 356         //
 357         // After the insertion, the tree looks like the following:
 358         //                     {}
 359         //              /     /        /
 360         //            a0     a2        a3
 361         //                 /  |  /     |
 362         //               a0  a3  a5    a0
 363         tree.insert(Execution(), {a3, a0});
 364         REQUIRE(tree.get_num_nodes() == 8);
 365         test_tree_iterator(tree, std::vector<PartialExecution>{PartialExecution{a0}, PartialExecution{a2, a0},
 366                                                                PartialExecution{a2, a3}, PartialExecution{a2, a5},
 367                                                                PartialExecution{a2}, PartialExecution{a3, a0},
 368                                                                PartialExecution{a3}, PartialExecution{}});
 369       }
 370     }
 371   }
 372
 373   SECTION("Insertion with non-obvious equivalent leaf")
 374   {
 375     const auto cd_1 = std::make_shared<ConditionallyDependentAction>(Transition::Type::UNKNOWN, 1);
 376     const auto i_2  = std::make_shared<IndependentAction>(Transition::Type::UNKNOWN, 2);
 377     const auto i_3  = std::make_shared<IndependentAction>(Transition::Type::UNKNOWN, 3);
 378     const auto d_1  = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 1);
 379     const auto d_2  = std::make_shared<DependentAction>(Transition::Type::UNKNOWN, 2);
 380     WakeupTree complex_tree;
 381     // After the insertions below, the tree looks like the following:
 382     //                {}
 383     //              /    /
 384     //            a0     a2
 385     //                 /  |  /
 386     //               a0  a3   a5
 387     complex_tree.insert(Execution(), {cd_1, i_2, d_1, i_3, d_2, d_2});
 388     complex_tree.insert(Execution(), {i_2, d_2, cd_1, d_1, i_3, d_2});
 389     complex_tree.insert(Execution(), {i_2, d_2, cd_1, i_3, d_2, d_1});
 390     REQUIRE(complex_tree.get_num_nodes() == 16);
 391   }
 392 }