| // Copyright (c) 2011 The LevelDB Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. See the AUTHORS file for names of contributors. |
| |
| #include "db/skiplist.h" |
| #include <set> |
| #include "leveldb/env.h" |
| #include "util/arena.h" |
| #include "util/hash.h" |
| #include "util/random.h" |
| #include "util/testharness.h" |
| |
| namespace leveldb { |
| |
| typedef uint64_t Key; |
| |
| struct Comparator { |
| int operator()(const Key& a, const Key& b) const { |
| if (a < b) { |
| return -1; |
| } else if (a > b) { |
| return +1; |
| } else { |
| return 0; |
| } |
| } |
| }; |
| |
| class SkipTest { }; |
| |
| TEST(SkipTest, Empty) { |
| Arena arena; |
| Comparator cmp; |
| SkipList<Key, Comparator> list(cmp, &arena); |
| ASSERT_TRUE(!list.Contains(10)); |
| |
| SkipList<Key, Comparator>::Iterator iter(&list); |
| ASSERT_TRUE(!iter.Valid()); |
| iter.SeekToFirst(); |
| ASSERT_TRUE(!iter.Valid()); |
| iter.Seek(100); |
| ASSERT_TRUE(!iter.Valid()); |
| iter.SeekToLast(); |
| ASSERT_TRUE(!iter.Valid()); |
| } |
| |
| TEST(SkipTest, InsertAndLookup) { |
| const int N = 2000; |
| const int R = 5000; |
| Random rnd(1000); |
| std::set<Key> keys; |
| Arena arena; |
| Comparator cmp; |
| SkipList<Key, Comparator> list(cmp, &arena); |
| for (int i = 0; i < N; i++) { |
| Key key = rnd.Next() % R; |
| if (keys.insert(key).second) { |
| list.Insert(key); |
| } |
| } |
| |
| for (int i = 0; i < R; i++) { |
| if (list.Contains(i)) { |
| ASSERT_EQ(keys.count(i), 1); |
| } else { |
| ASSERT_EQ(keys.count(i), 0); |
| } |
| } |
| |
| // Simple iterator tests |
| { |
| SkipList<Key, Comparator>::Iterator iter(&list); |
| ASSERT_TRUE(!iter.Valid()); |
| |
| iter.Seek(0); |
| ASSERT_TRUE(iter.Valid()); |
| ASSERT_EQ(*(keys.begin()), iter.key()); |
| |
| iter.SeekToFirst(); |
| ASSERT_TRUE(iter.Valid()); |
| ASSERT_EQ(*(keys.begin()), iter.key()); |
| |
| iter.SeekToLast(); |
| ASSERT_TRUE(iter.Valid()); |
| ASSERT_EQ(*(keys.rbegin()), iter.key()); |
| } |
| |
| // Forward iteration test |
| for (int i = 0; i < R; i++) { |
| SkipList<Key, Comparator>::Iterator iter(&list); |
| iter.Seek(i); |
| |
| // Compare against model iterator |
| std::set<Key>::iterator model_iter = keys.lower_bound(i); |
| for (int j = 0; j < 3; j++) { |
| if (model_iter == keys.end()) { |
| ASSERT_TRUE(!iter.Valid()); |
| break; |
| } else { |
| ASSERT_TRUE(iter.Valid()); |
| ASSERT_EQ(*model_iter, iter.key()); |
| ++model_iter; |
| iter.Next(); |
| } |
| } |
| } |
| |
| // Backward iteration test |
| { |
| SkipList<Key, Comparator>::Iterator iter(&list); |
| iter.SeekToLast(); |
| |
| // Compare against model iterator |
| for (std::set<Key>::reverse_iterator model_iter = keys.rbegin(); |
| model_iter != keys.rend(); |
| ++model_iter) { |
| ASSERT_TRUE(iter.Valid()); |
| ASSERT_EQ(*model_iter, iter.key()); |
| iter.Prev(); |
| } |
| ASSERT_TRUE(!iter.Valid()); |
| } |
| } |
| |
| // We want to make sure that with a single writer and multiple |
| // concurrent readers (with no synchronization other than when a |
| // reader's iterator is created), the reader always observes all the |
| // data that was present in the skip list when the iterator was |
| // constructor. Because insertions are happening concurrently, we may |
| // also observe new values that were inserted since the iterator was |
| // constructed, but we should never miss any values that were present |
| // at iterator construction time. |
| // |
| // We generate multi-part keys: |
| // <key,gen,hash> |
| // where: |
| // key is in range [0..K-1] |
| // gen is a generation number for key |
| // hash is hash(key,gen) |
| // |
| // The insertion code picks a random key, sets gen to be 1 + the last |
| // generation number inserted for that key, and sets hash to Hash(key,gen). |
| // |
| // At the beginning of a read, we snapshot the last inserted |
| // generation number for each key. We then iterate, including random |
| // calls to Next() and Seek(). For every key we encounter, we |
| // check that it is either expected given the initial snapshot or has |
| // been concurrently added since the iterator started. |
| class ConcurrentTest { |
| private: |
| static const uint32_t K = 4; |
| |
| static uint64_t key(Key key) { return (key >> 40); } |
| static uint64_t gen(Key key) { return (key >> 8) & 0xffffffffu; } |
| static uint64_t hash(Key key) { return key & 0xff; } |
| |
| static uint64_t HashNumbers(uint64_t k, uint64_t g) { |
| uint64_t data[2] = { k, g }; |
| return Hash(reinterpret_cast<char*>(data), sizeof(data), 0); |
| } |
| |
| static Key MakeKey(uint64_t k, uint64_t g) { |
| assert(sizeof(Key) == sizeof(uint64_t)); |
| assert(k <= K); // We sometimes pass K to seek to the end of the skiplist |
| assert(g <= 0xffffffffu); |
| return ((k << 40) | (g << 8) | (HashNumbers(k, g) & 0xff)); |
| } |
| |
| static bool IsValidKey(Key k) { |
| return hash(k) == (HashNumbers(key(k), gen(k)) & 0xff); |
| } |
| |
| static Key RandomTarget(Random* rnd) { |
| switch (rnd->Next() % 10) { |
| case 0: |
| // Seek to beginning |
| return MakeKey(0, 0); |
| case 1: |
| // Seek to end |
| return MakeKey(K, 0); |
| default: |
| // Seek to middle |
| return MakeKey(rnd->Next() % K, 0); |
| } |
| } |
| |
| // Per-key generation |
| struct State { |
| port::AtomicPointer generation[K]; |
| void Set(int k, intptr_t v) { |
| generation[k].Release_Store(reinterpret_cast<void*>(v)); |
| } |
| intptr_t Get(int k) { |
| return reinterpret_cast<intptr_t>(generation[k].Acquire_Load()); |
| } |
| |
| State() { |
| for (int k = 0; k < K; k++) { |
| Set(k, 0); |
| } |
| } |
| }; |
| |
| // Current state of the test |
| State current_; |
| |
| Arena arena_; |
| |
| // SkipList is not protected by mu_. We just use a single writer |
| // thread to modify it. |
| SkipList<Key, Comparator> list_; |
| |
| public: |
| ConcurrentTest() : list_(Comparator(), &arena_) { } |
| |
| // REQUIRES: External synchronization |
| void WriteStep(Random* rnd) { |
| const uint32_t k = rnd->Next() % K; |
| const intptr_t g = current_.Get(k) + 1; |
| const Key key = MakeKey(k, g); |
| list_.Insert(key); |
| current_.Set(k, g); |
| } |
| |
| void ReadStep(Random* rnd) { |
| // Remember the initial committed state of the skiplist. |
| State initial_state; |
| for (int k = 0; k < K; k++) { |
| initial_state.Set(k, current_.Get(k)); |
| } |
| |
| Key pos = RandomTarget(rnd); |
| SkipList<Key, Comparator>::Iterator iter(&list_); |
| iter.Seek(pos); |
| while (true) { |
| Key current; |
| if (!iter.Valid()) { |
| current = MakeKey(K, 0); |
| } else { |
| current = iter.key(); |
| ASSERT_TRUE(IsValidKey(current)) << current; |
| } |
| ASSERT_LE(pos, current) << "should not go backwards"; |
| |
| // Verify that everything in [pos,current) was not present in |
| // initial_state. |
| while (pos < current) { |
| ASSERT_LT(key(pos), K) << pos; |
| |
| // Note that generation 0 is never inserted, so it is ok if |
| // <*,0,*> is missing. |
| ASSERT_TRUE((gen(pos) == 0) || |
| (gen(pos) > initial_state.Get(key(pos))) |
| ) << "key: " << key(pos) |
| << "; gen: " << gen(pos) |
| << "; initgen: " |
| << initial_state.Get(key(pos)); |
| |
| // Advance to next key in the valid key space |
| if (key(pos) < key(current)) { |
| pos = MakeKey(key(pos) + 1, 0); |
| } else { |
| pos = MakeKey(key(pos), gen(pos) + 1); |
| } |
| } |
| |
| if (!iter.Valid()) { |
| break; |
| } |
| |
| if (rnd->Next() % 2) { |
| iter.Next(); |
| pos = MakeKey(key(pos), gen(pos) + 1); |
| } else { |
| Key new_target = RandomTarget(rnd); |
| if (new_target > pos) { |
| pos = new_target; |
| iter.Seek(new_target); |
| } |
| } |
| } |
| } |
| }; |
| const uint32_t ConcurrentTest::K; |
| |
| // Simple test that does single-threaded testing of the ConcurrentTest |
| // scaffolding. |
| TEST(SkipTest, ConcurrentWithoutThreads) { |
| ConcurrentTest test; |
| Random rnd(test::RandomSeed()); |
| for (int i = 0; i < 10000; i++) { |
| test.ReadStep(&rnd); |
| test.WriteStep(&rnd); |
| } |
| } |
| |
| class TestState { |
| public: |
| ConcurrentTest t_; |
| int seed_; |
| port::AtomicPointer quit_flag_; |
| |
| enum ReaderState { |
| STARTING, |
| RUNNING, |
| DONE |
| }; |
| |
| explicit TestState(int s) |
| : seed_(s), |
| quit_flag_(NULL), |
| state_(STARTING), |
| state_cv_(&mu_) {} |
| |
| void Wait(ReaderState s) { |
| mu_.Lock(); |
| while (state_ != s) { |
| state_cv_.Wait(); |
| } |
| mu_.Unlock(); |
| } |
| |
| void Change(ReaderState s) { |
| mu_.Lock(); |
| state_ = s; |
| state_cv_.Signal(); |
| mu_.Unlock(); |
| } |
| |
| private: |
| port::Mutex mu_; |
| ReaderState state_; |
| port::CondVar state_cv_; |
| }; |
| |
| static void ConcurrentReader(void* arg) { |
| TestState* state = reinterpret_cast<TestState*>(arg); |
| Random rnd(state->seed_); |
| int64_t reads = 0; |
| state->Change(TestState::RUNNING); |
| while (!state->quit_flag_.Acquire_Load()) { |
| state->t_.ReadStep(&rnd); |
| ++reads; |
| } |
| state->Change(TestState::DONE); |
| } |
| |
| static void RunConcurrent(int run) { |
| const int seed = test::RandomSeed() + (run * 100); |
| Random rnd(seed); |
| const int N = 1000; |
| const int kSize = 1000; |
| for (int i = 0; i < N; i++) { |
| if ((i % 100) == 0) { |
| fprintf(stderr, "Run %d of %d\n", i, N); |
| } |
| TestState state(seed + 1); |
| Env::Default()->Schedule(ConcurrentReader, &state); |
| state.Wait(TestState::RUNNING); |
| for (int i = 0; i < kSize; i++) { |
| state.t_.WriteStep(&rnd); |
| } |
| state.quit_flag_.Release_Store(&state); // Any non-NULL arg will do |
| state.Wait(TestState::DONE); |
| } |
| } |
| |
| TEST(SkipTest, Concurrent1) { RunConcurrent(1); } |
| TEST(SkipTest, Concurrent2) { RunConcurrent(2); } |
| TEST(SkipTest, Concurrent3) { RunConcurrent(3); } |
| TEST(SkipTest, Concurrent4) { RunConcurrent(4); } |
| TEST(SkipTest, Concurrent5) { RunConcurrent(5); } |
| |
| } // namespace leveldb |
| |
| int main(int argc, char** argv) { |
| return leveldb::test::RunAllTests(); |
| } |