1  // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
  2  // Use of this source code is governed by a BSD-style license that can be
  3  // found in the LICENSE file. See the AUTHORS file for names of contributors.
  4  
  5  #include "leveldb/cache.h"
  6  
  7  #include <vector>
  8  #include "util/coding.h"
  9  #include "util/testharness.h"
 10  
 11  namespace leveldb {
 12  
 13  // Conversions between numeric keys/values and the types expected by Cache.
 14  static std::string EncodeKey(int k) {
 15    std::string result;
 16    PutFixed32(&result, k);
 17    return result;
 18  }
 19  static int DecodeKey(const Slice& k) {
 20    assert(k.size() == 4);
 21    return DecodeFixed32(k.data());
 22  }
 23  static void* EncodeValue(uintptr_t v) { return reinterpret_cast<void*>(v); }
 24  static int DecodeValue(void* v) { return reinterpret_cast<uintptr_t>(v); }
 25  
 26  class CacheTest {
 27   public:
 28    static void Deleter(const Slice& key, void* v) {
 29      current_->deleted_keys_.push_back(DecodeKey(key));
 30      current_->deleted_values_.push_back(DecodeValue(v));
 31    }
 32  
 33    static const int kCacheSize = 1000;
 34    std::vector<int> deleted_keys_;
 35    std::vector<int> deleted_values_;
 36    Cache* cache_;
 37  
 38    CacheTest() : cache_(NewLRUCache(kCacheSize)) { current_ = this; }
 39  
 40    ~CacheTest() { delete cache_; }
 41  
 42    int Lookup(int key) {
 43      Cache::Handle* handle = cache_->Lookup(EncodeKey(key));
 44      const int r = (handle == nullptr) ? -1 : DecodeValue(cache_->Value(handle));
 45      if (handle != nullptr) {
 46        cache_->Release(handle);
 47      }
 48      return r;
 49    }
 50  
 51    void Insert(int key, int value, int charge = 1) {
 52      cache_->Release(cache_->Insert(EncodeKey(key), EncodeValue(value), charge,
 53                                     &CacheTest::Deleter));
 54    }
 55  
 56    Cache::Handle* InsertAndReturnHandle(int key, int value, int charge = 1) {
 57      return cache_->Insert(EncodeKey(key), EncodeValue(value), charge,
 58                            &CacheTest::Deleter);
 59    }
 60  
 61    void Erase(int key) { cache_->Erase(EncodeKey(key)); }
 62  
 63    static CacheTest* current_;
 64  };
 65  CacheTest* CacheTest::current_;
 66  
 67  TEST(CacheTest, HitAndMiss) {
 68    ASSERT_EQ(-1, Lookup(100));
 69  
 70    Insert(100, 101);
 71    ASSERT_EQ(101, Lookup(100));
 72    ASSERT_EQ(-1, Lookup(200));
 73    ASSERT_EQ(-1, Lookup(300));
 74  
 75    Insert(200, 201);
 76    ASSERT_EQ(101, Lookup(100));
 77    ASSERT_EQ(201, Lookup(200));
 78    ASSERT_EQ(-1, Lookup(300));
 79  
 80    Insert(100, 102);
 81    ASSERT_EQ(102, Lookup(100));
 82    ASSERT_EQ(201, Lookup(200));
 83    ASSERT_EQ(-1, Lookup(300));
 84  
 85    ASSERT_EQ(1, deleted_keys_.size());
 86    ASSERT_EQ(100, deleted_keys_[0]);
 87    ASSERT_EQ(101, deleted_values_[0]);
 88  }
 89  
 90  TEST(CacheTest, Erase) {
 91    Erase(200);
 92    ASSERT_EQ(0, deleted_keys_.size());
 93  
 94    Insert(100, 101);
 95    Insert(200, 201);
 96    Erase(100);
 97    ASSERT_EQ(-1, Lookup(100));
 98    ASSERT_EQ(201, Lookup(200));
 99    ASSERT_EQ(1, deleted_keys_.size());
100    ASSERT_EQ(100, deleted_keys_[0]);
101    ASSERT_EQ(101, deleted_values_[0]);
102  
103    Erase(100);
104    ASSERT_EQ(-1, Lookup(100));
105    ASSERT_EQ(201, Lookup(200));
106    ASSERT_EQ(1, deleted_keys_.size());
107  }
108  
109  TEST(CacheTest, EntriesArePinned) {
110    Insert(100, 101);
111    Cache::Handle* h1 = cache_->Lookup(EncodeKey(100));
112    ASSERT_EQ(101, DecodeValue(cache_->Value(h1)));
113  
114    Insert(100, 102);
115    Cache::Handle* h2 = cache_->Lookup(EncodeKey(100));
116    ASSERT_EQ(102, DecodeValue(cache_->Value(h2)));
117    ASSERT_EQ(0, deleted_keys_.size());
118  
119    cache_->Release(h1);
120    ASSERT_EQ(1, deleted_keys_.size());
121    ASSERT_EQ(100, deleted_keys_[0]);
122    ASSERT_EQ(101, deleted_values_[0]);
123  
124    Erase(100);
125    ASSERT_EQ(-1, Lookup(100));
126    ASSERT_EQ(1, deleted_keys_.size());
127  
128    cache_->Release(h2);
129    ASSERT_EQ(2, deleted_keys_.size());
130    ASSERT_EQ(100, deleted_keys_[1]);
131    ASSERT_EQ(102, deleted_values_[1]);
132  }
133  
134  TEST(CacheTest, EvictionPolicy) {
135    Insert(100, 101);
136    Insert(200, 201);
137    Insert(300, 301);
138    Cache::Handle* h = cache_->Lookup(EncodeKey(300));
139  
140    // Frequently used entry must be kept around,
141    // as must things that are still in use.
142    for (int i = 0; i < kCacheSize + 100; i++) {
143      Insert(1000 + i, 2000 + i);
144      ASSERT_EQ(2000 + i, Lookup(1000 + i));
145      ASSERT_EQ(101, Lookup(100));
146    }
147    ASSERT_EQ(101, Lookup(100));
148    ASSERT_EQ(-1, Lookup(200));
149    ASSERT_EQ(301, Lookup(300));
150    cache_->Release(h);
151  }
152  
153  TEST(CacheTest, UseExceedsCacheSize) {
154    // Overfill the cache, keeping handles on all inserted entries.
155    std::vector<Cache::Handle*> h;
156    for (int i = 0; i < kCacheSize + 100; i++) {
157      h.push_back(InsertAndReturnHandle(1000 + i, 2000 + i));
158    }
159  
160    // Check that all the entries can be found in the cache.
161    for (int i = 0; i < h.size(); i++) {
162      ASSERT_EQ(2000 + i, Lookup(1000 + i));
163    }
164  
165    for (int i = 0; i < h.size(); i++) {
166      cache_->Release(h[i]);
167    }
168  }
169  
170  TEST(CacheTest, HeavyEntries) {
171    // Add a bunch of light and heavy entries and then count the combined
172    // size of items still in the cache, which must be approximately the
173    // same as the total capacity.
174    const int kLight = 1;
175    const int kHeavy = 10;
176    int added = 0;
177    int index = 0;
178    while (added < 2 * kCacheSize) {
179      const int weight = (index & 1) ? kLight : kHeavy;
180      Insert(index, 1000 + index, weight);
181      added += weight;
182      index++;
183    }
184  
185    int cached_weight = 0;
186    for (int i = 0; i < index; i++) {
187      const int weight = (i & 1 ? kLight : kHeavy);
188      int r = Lookup(i);
189      if (r >= 0) {
190        cached_weight += weight;
191        ASSERT_EQ(1000 + i, r);
192      }
193    }
194    ASSERT_LE(cached_weight, kCacheSize + kCacheSize / 10);
195  }
196  
197  TEST(CacheTest, NewId) {
198    uint64_t a = cache_->NewId();
199    uint64_t b = cache_->NewId();
200    ASSERT_NE(a, b);
201  }
202  
203  TEST(CacheTest, Prune) {
204    Insert(1, 100);
205    Insert(2, 200);
206  
207    Cache::Handle* handle = cache_->Lookup(EncodeKey(1));
208    ASSERT_TRUE(handle);
209    cache_->Prune();
210    cache_->Release(handle);
211  
212    ASSERT_EQ(100, Lookup(1));
213    ASSERT_EQ(-1, Lookup(2));
214  }
215  
216  TEST(CacheTest, ZeroSizeCache) {
217    delete cache_;
218    cache_ = NewLRUCache(0);
219  
220    Insert(1, 100);
221    ASSERT_EQ(-1, Lookup(1));
222  }
223  
224  }  // namespace leveldb
225  
226  int main(int argc, char** argv) { return leveldb::test::RunAllTests(); }