Let QuicLRUCache take explicit hasher. Also added various iterators, change Lookup to return iterator and add Erase function.

PiperOrigin-RevId: 411112825

quic/core/crypto/quic_compressed_certs_cache.cc

diff --git a/quic/core/crypto/quic_compressed_certs_cache.cc b/quic/core/crypto/quic_compressed_certs_cache.cc
index fcc081f..6377a64 100644
--- a/quic/core/crypto/quic_compressed_certs_cache.cc
+++ b/quic/core/crypto/quic_compressed_certs_cache.cc
@@ -81,7 +81,11 @@
 
   uint64_t key = ComputeUncompressedCertsHash(uncompressed_certs);
 
-  CachedCerts* cached_value = certs_cache_.Lookup(key);
+  CachedCerts* cached_value = nullptr;
+  auto iter = certs_cache_.Lookup(key);
+  if (iter != certs_cache_.end()) {
+    cached_value = iter->second.get();
+  }
   if (cached_value != nullptr &&
       cached_value->MatchesUncompressedCerts(uncompressed_certs)) {
     return cached_value->compressed_cert();

quic/core/quic_lru_cache.h

diff --git a/quic/core/quic_lru_cache.h b/quic/core/quic_lru_cache.h
index 67541ee..44024b6 100644
--- a/quic/core/quic_lru_cache.h
+++ b/quic/core/quic_lru_cache.h
@@ -19,13 +19,36 @@
 // This cache CANNOT be shared by multiple threads (even with locks) because
 // Value* returned by Lookup() can be invalid if the entry is evicted by other
 // threads.
-template <class K, class V>
+template <class K, class V, class Hash = std::hash<K>,
+          class Eq = std::equal_to<K>>
 class QUIC_NO_EXPORT QuicLRUCache {
+ private:
+  using HashMapType =
+      typename quiche::QuicheLinkedHashMap<K, std::unique_ptr<V>, Hash, Eq>;
+
  public:
+  // The iterator, if valid, points to std::pair<K, std::unique_ptr<V>>.
+  using iterator = typename HashMapType::iterator;
+  using const_iterator = typename HashMapType::const_iterator;
+  using reverse_iterator = typename HashMapType::reverse_iterator;
+  using const_reverse_iterator = typename HashMapType::const_reverse_iterator;
+
   explicit QuicLRUCache(size_t capacity) : capacity_(capacity) {}
   QuicLRUCache(const QuicLRUCache&) = delete;
   QuicLRUCache& operator=(const QuicLRUCache&) = delete;
 
+  iterator begin() { return cache_.begin(); }
+  const_iterator begin() const { return cache_.begin(); }
+
+  iterator end() { return cache_.end(); }
+  const_iterator end() const { return cache_.end(); }
+
+  reverse_iterator rbegin() { return cache_.rbegin(); }
+  const_reverse_iterator rbegin() const { return cache_.rbegin(); }
+
+  reverse_iterator rend() { return cache_.rend(); }
+  const_reverse_iterator rend() const { return cache_.rend(); }
+
   // Inserts one unit of |key|, |value| pair to the cache. Cache takes ownership
   // of inserted |value|.
   void Insert(const K& key, std::unique_ptr<V> value) {
@@ -41,22 +64,21 @@
     QUICHE_DCHECK_LE(cache_.size(), capacity_);
   }
 
-  // If cache contains an entry for |key|, return a pointer to it. This returned
-  // value is guaranteed to be valid until Insert or Clear.
-  // Else return nullptr.
-  V* Lookup(const K& key) {
-    auto it = cache_.find(key);
-    if (it == cache_.end()) {
-      return nullptr;
+  iterator Lookup(const K& key) {
+    auto iter = cache_.find(key);
+    if (iter == cache_.end()) {
+      return iter;
     }
 
-    std::unique_ptr<V> value = std::move(it->second);
-    cache_.erase(it);
+    std::unique_ptr<V> value = std::move(iter->second);
+    cache_.erase(iter);
     auto result = cache_.emplace(key, std::move(value));
     QUICHE_DCHECK(result.second);
-    return result.first->second.get();
+    return result.first;
   }
 
+  iterator Erase(iterator iter) { return cache_.erase(iter); }
+
   // Removes all entries from the cache.
   void Clear() { cache_.clear(); }
 
@@ -67,7 +89,7 @@
   size_t Size() const { return cache_.size(); }
 
  private:
-  quiche::QuicheLinkedHashMap<K, std::unique_ptr<V>> cache_;
+  quiche::QuicheLinkedHashMap<K, std::unique_ptr<V>, Hash, Eq> cache_;
   const size_t capacity_;
 };
 

quic/core/quic_lru_cache_test.cc

diff --git a/quic/core/quic_lru_cache_test.cc b/quic/core/quic_lru_cache_test.cc
index d2c0505..8c6b5b8 100644
--- a/quic/core/quic_lru_cache_test.cc
+++ b/quic/core/quic_lru_cache_test.cc
@@ -18,7 +18,7 @@
 
 TEST(QuicLRUCacheTest, InsertAndLookup) {
   QuicLRUCache<int, CachedItem> cache(5);
-  EXPECT_EQ(nullptr, cache.Lookup(1));
+  EXPECT_EQ(cache.end(), cache.Lookup(1));
   EXPECT_EQ(0u, cache.Size());
   EXPECT_EQ(5u, cache.MaxSize());
 
@@ -26,18 +26,23 @@
   std::unique_ptr<CachedItem> item1(new CachedItem(11));
   cache.Insert(1, std::move(item1));
   EXPECT_EQ(1u, cache.Size());
-  EXPECT_EQ(11u, cache.Lookup(1)->value);
+  EXPECT_EQ(11u, cache.Lookup(1)->second->value);
 
   // Check that item 2 overrides item 1.
   std::unique_ptr<CachedItem> item2(new CachedItem(12));
   cache.Insert(1, std::move(item2));
   EXPECT_EQ(1u, cache.Size());
-  EXPECT_EQ(12u, cache.Lookup(1)->value);
+  EXPECT_EQ(12u, cache.Lookup(1)->second->value);
 
   std::unique_ptr<CachedItem> item3(new CachedItem(13));
   cache.Insert(3, std::move(item3));
   EXPECT_EQ(2u, cache.Size());
-  EXPECT_EQ(13u, cache.Lookup(3)->value);
+  auto iter = cache.Lookup(3);
+  ASSERT_NE(cache.end(), iter);
+  EXPECT_EQ(13u, iter->second->value);
+  cache.Erase(iter);
+  ASSERT_EQ(cache.end(), cache.Lookup(3));
+  EXPECT_EQ(1u, cache.Size());
 
   // No memory leakage.
   cache.Clear();
@@ -56,15 +61,15 @@
   EXPECT_EQ(3u, cache.MaxSize());
 
   // Make sure item 1 is evicted.
-  EXPECT_EQ(nullptr, cache.Lookup(1));
-  EXPECT_EQ(14u, cache.Lookup(4)->value);
+  EXPECT_EQ(cache.end(), cache.Lookup(1));
+  EXPECT_EQ(14u, cache.Lookup(4)->second->value);
 
-  EXPECT_EQ(12u, cache.Lookup(2)->value);
+  EXPECT_EQ(12u, cache.Lookup(2)->second->value);
   std::unique_ptr<CachedItem> item5(new CachedItem(15));
   cache.Insert(5, std::move(item5));
   // Make sure item 3 is evicted.
-  EXPECT_EQ(nullptr, cache.Lookup(3));
-  EXPECT_EQ(15u, cache.Lookup(5)->value);
+  EXPECT_EQ(cache.end(), cache.Lookup(3));
+  EXPECT_EQ(15u, cache.Lookup(5)->second->value);
 
   // No memory leakage.
   cache.Clear();