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libutil: Use heterogeneous lookup for LRUCache

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This gets rid of some ugly std::string_view -> std::string
conversions, which are an eye-sore and lead to extra copying.
This commit is contained in:
Sergei Zimmerman 2025-05-14 21:42:35 +00:00
parent 90d70aa4c9
commit cd61e922ff
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GPG key ID: A9B0B557CA632325
2 changed files with 13 additions and 10 deletions
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10
src/libstore/store-api.cc
View file

@ -570,7 +570,7 @@ bool Store::isValidPath(const StorePath & storePath)
{ {
{ {
auto state_(state.lock()); auto state_(state.lock());
auto res = state_->pathInfoCache.get(std::string(storePath.to_string())); auto res = state_->pathInfoCache.get(storePath.to_string());
if (res && res->isKnownNow()) { if (res && res->isKnownNow()) {
stats.narInfoReadAverted++; stats.narInfoReadAverted++;
return res->didExist(); return res->didExist();
@ -582,7 +582,7 @@ bool Store::isValidPath(const StorePath & storePath)
if (res.first != NarInfoDiskCache::oUnknown) { if (res.first != NarInfoDiskCache::oUnknown) {
stats.narInfoReadAverted++; stats.narInfoReadAverted++;
auto state_(state.lock()); auto state_(state.lock());
state_->pathInfoCache.upsert(std::string(storePath.to_string()), state_->pathInfoCache.upsert(storePath.to_string(),
res.first == NarInfoDiskCache::oInvalid ? PathInfoCacheValue{} : PathInfoCacheValue { .value = res.second }); res.first == NarInfoDiskCache::oInvalid ? PathInfoCacheValue{} : PathInfoCacheValue { .value = res.second });
return res.first == NarInfoDiskCache::oValid; return res.first == NarInfoDiskCache::oValid;
} }
@ -641,7 +641,7 @@ std::optional<std::shared_ptr<const ValidPathInfo>> Store::queryPathInfoFromClie
auto hashPart = std::string(storePath.hashPart()); auto hashPart = std::string(storePath.hashPart());
{ {
auto res = state.lock()->pathInfoCache.get(std::string(storePath.to_string())); auto res = state.lock()->pathInfoCache.get(storePath.to_string());
if (res && res->isKnownNow()) { if (res && res->isKnownNow()) {
stats.narInfoReadAverted++; stats.narInfoReadAverted++;
if (res->didExist()) if (res->didExist())
@ -657,7 +657,7 @@ std::optional<std::shared_ptr<const ValidPathInfo>> Store::queryPathInfoFromClie
stats.narInfoReadAverted++; stats.narInfoReadAverted++;
{ {
auto state_(state.lock()); auto state_(state.lock());
state_->pathInfoCache.upsert(std::string(storePath.to_string()), state_->pathInfoCache.upsert(storePath.to_string(),
res.first == NarInfoDiskCache::oInvalid ? PathInfoCacheValue{} : PathInfoCacheValue{ .value = res.second }); res.first == NarInfoDiskCache::oInvalid ? PathInfoCacheValue{} : PathInfoCacheValue{ .value = res.second });
if (res.first == NarInfoDiskCache::oInvalid || if (res.first == NarInfoDiskCache::oInvalid ||
!goodStorePath(storePath, res.second->path)) !goodStorePath(storePath, res.second->path))
@ -701,7 +701,7 @@ void Store::queryPathInfo(const StorePath & storePath,
{ {
auto state_(state.lock()); auto state_(state.lock());
state_->pathInfoCache.upsert(std::string(storePath.to_string()), PathInfoCacheValue { .value = info }); state_->pathInfoCache.upsert(storePath.to_string(), PathInfoCacheValue { .value = info });
} }
if (!info || !goodStorePath(storePath, info->path)) { if (!info || !goodStorePath(storePath, info->path)) {

13
src/libutil/include/nix/util/lru-cache.hh
View file

@ -11,7 +11,7 @@ namespace nix {
/** /**
* A simple least-recently used cache. Not thread-safe. * A simple least-recently used cache. Not thread-safe.
*/ */
template<typename Key, typename Value> template<typename Key, typename Value, typename Compare = std::less<>>
class LRUCache class LRUCache
{ {
private: private:
@ -22,7 +22,7 @@ private:
// and LRU. // and LRU.
struct LRUIterator; struct LRUIterator;
using Data = std::map<Key, std::pair<LRUIterator, Value>>; using Data = std::map<Key, std::pair<LRUIterator, Value>, Compare>;
using LRU = std::list<typename Data::iterator>; using LRU = std::list<typename Data::iterator>;
struct LRUIterator struct LRUIterator
@ -43,7 +43,8 @@ public:
/** /**
* Insert or upsert an item in the cache. * Insert or upsert an item in the cache.
*/ */
void upsert(const Key & key, const Value & value) template<typename K>
void upsert(const K & key, const Value & value)
{ {
if (capacity == 0) if (capacity == 0)
return; return;
@ -68,7 +69,8 @@ public:
i->second.first.it = j; i->second.first.it = j;
} }
bool erase(const Key & key) template<typename K>
bool erase(const K & key)
{ {
auto i = data.find(key); auto i = data.find(key);
if (i == data.end()) if (i == data.end())
@ -82,7 +84,8 @@ public:
* Look up an item in the cache. If it exists, it becomes the most * Look up an item in the cache. If it exists, it becomes the most
* recently used item. * recently used item.
* */ * */
std::optional<Value> get(const Key & key) template<typename K>
std::optional<Value> get(const K & key)
{ {
auto i = data.find(key); auto i = data.find(key);
if (i == data.end()) if (i == data.end())