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Simplify LruCache a little bit. (#199)

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scturtle 2017-12-28 15:27:42 +08:00 committed by Fangrui Song
parent d7d8b820ac
commit 32bcac38af
1 changed files with 7 additions and 22 deletions
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29
src/lru_cache.h
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@ -40,6 +40,7 @@ struct LruCache {
uint32_t score = 0;
TKey key;
std::shared_ptr<TValue> value;
bool operator<(const Entry &other) const { return score < other.score; }
};
void IncrementScore();
@ -69,8 +70,8 @@ std::shared_ptr<TValue> LruCache<TKey, TValue>::TryGet(const TKey& key) {
// Assign new score.
for (Entry& entry : entries_) {
if (entry.key == key) {
IncrementScore();
entry.score = next_score_;
IncrementScore();
return entry.value;
}
}
@ -94,25 +95,12 @@ std::shared_ptr<TValue> LruCache<TKey, TValue>::TryTake(const TKey& key) {
template <typename TKey, typename TValue>
void LruCache<TKey, TValue>::Insert(const TKey& key,
const std::shared_ptr<TValue>& value) {
if (entries_.size() >= max_entries_) {
// Find entry with the lowest score.
size_t lowest_idx = 0;
uint32_t lowest_score = std::numeric_limits<uint32_t>::max();
for (size_t i = 0; i < entries_.size(); ++i) {
if (entries_[i].score < lowest_score) {
lowest_idx = i;
lowest_score = entries_[i].score;
}
}
// Remove it.
entries_.erase(entries_.begin() + lowest_idx);
}
IncrementScore();
if (entries_.size() >= max_entries_)
entries_.erase(std::min_element(entries_.begin(), entries_.end()));
Entry entry;
entry.score = next_score_;
IncrementScore();
entry.key = key;
entry.value = value;
entries_.push_back(entry);
@ -129,12 +117,9 @@ void LruCache<TKey, TValue>::IterateValues(TFunc func) {
template <typename TKey, typename TValue>
void LruCache<TKey, TValue>::IncrementScore() {
next_score_ += 1;
// Overflow.
if (next_score_ == 0) {
std::sort(entries_.begin(), entries_.end(),
[](const Entry& a, const Entry& b) { return a.score < b.score; });
if (++next_score_ == 0) {
std::sort(entries_.begin(), entries_.end());
for (Entry& entry : entries_)
entry.score = next_score_++;
}