From 58841ef12f6cba1bb622353c1fcaa0e3c6fb46c9 Mon Sep 17 00:00:00 2001 From: Ilya Zhuravlev Date: Tue, 23 Oct 2012 01:18:44 +0400 Subject: Add dummy and LevelDB database backends --- src/leveldb/db/skiplist_test.cc | 378 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 378 insertions(+) create mode 100644 src/leveldb/db/skiplist_test.cc (limited to 'src/leveldb/db/skiplist_test.cc') diff --git a/src/leveldb/db/skiplist_test.cc b/src/leveldb/db/skiplist_test.cc new file mode 100644 index 000000000..c78f4b4fb --- /dev/null +++ b/src/leveldb/db/skiplist_test.cc @@ -0,0 +1,378 @@ +// 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 +#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 list(cmp, &arena); + ASSERT_TRUE(!list.Contains(10)); + + SkipList::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 keys; + Arena arena; + Comparator cmp; + SkipList 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::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::Iterator iter(&list); + iter.Seek(i); + + // Compare against model iterator + std::set::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::Iterator iter(&list); + iter.SeekToLast(); + + // Compare against model iterator + for (std::set::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: +// +// 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(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(v)); + } + intptr_t Get(int k) { + return reinterpret_cast(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 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::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(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(); +} -- cgit v1.2.3