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refactor(cache): move rwlock from LruEntry to FileStore, to reduce memory usage #1149

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Merged
EricHuangqx merged 3 commits into from
Mar 20, 2026
Merged

refactor(cache): move rwlock from LruEntry to FileStore, to reduce memory usage #1149

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8eab878
refactor(cache): lazy initialize rwlock to reduce memory usage
xiaoyang-hhh Mar 19, 2026
f073493
fix build
xiaoyang-hhh Mar 19, 2026
b33c5b9
use defer to release
xiaoyang-hhh Mar 20, 2026
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8 changes: 6 additions & 2 deletions fs/cache/full_file_cache/cache_pool.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -135,8 +135,10 @@ int FileCachePool::evict(std::string_view filename) {
lru_.mark_key_cleared(lruEntry->lruIter);
}
int err = 0;
auto cacheStore = static_cast<FileCacheStore*>(open(filePath, O_RDWR, 0644));
DEFER(cacheStore->release());
{
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@lihuiba lihuiba Mar 19, 2026

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DEFER(cacheStore->release())

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@xiaoyang-hhh xiaoyang-hhh Mar 20, 2026

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done

photon::scoped_rwlock rl(lruEntry->rw_lock_, photon::WLOCK);
photon::scoped_rwlock rl(cacheStore->rw_lock(), photon::WLOCK);
err = mediaFs_->truncate(filePath.data(), 0);
lruEntry->truncate_done = false;
}
Expand Down Expand Up @@ -256,8 +258,10 @@ void FileCachePool::eviction() {
continue;
}

auto cacheStore = static_cast<FileCacheStore*>(open(fileName, O_RDWR, 0644));
DEFER(cacheStore->release());
{
photon::scoped_rwlock rl(lruEntry->rw_lock_, photon::WLOCK);
photon::scoped_rwlock rl(cacheStore->rw_lock(), photon::WLOCK);
err = mediaFs_->truncate(fileName.data(), 0);
lruEntry->truncate_done = false;
}
Expand Down
6 changes: 2 additions & 4 deletions fs/cache/full_file_cache/cache_pool.h
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Original file line number Diff line number Diff line change
Expand Up @@ -45,9 +45,6 @@ class FileCachePool : public photon::fs::ICachePool {

void Init();

// pathname must begin with '/'
photon::fs::ICacheStore *do_open(std::string_view pathname, int flags, mode_t mode) override;

int set_quota(std::string_view pathname, size_t quota) override;
int stat(photon::fs::CacheStat *stat,
std::string_view pathname = std::string_view(nullptr, 0)) override;
Expand All @@ -64,7 +61,6 @@ class FileCachePool : public photon::fs::ICachePool {
uint32_t lruIter;
int openCount;
uint64_t size;
photon::rwlock rw_lock_;
bool truncate_done;
};

Expand All @@ -81,6 +77,8 @@ class FileCachePool : public photon::fs::ICachePool {
uint64_t updateSpace(FileNameMap::iterator iter, uint64_t size);

protected:
// pathname must begin with '/'
photon::fs::ICacheStore *do_open(std::string_view pathname, int flags, mode_t mode) override;
photon::fs::IFile *openMedia(std::string_view name, int flags, int mode);

static uint64_t timerHandler(void *data);
Expand Down
7 changes: 3 additions & 4 deletions fs/cache/full_file_cache/cache_store.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -51,8 +51,7 @@ FileCacheStore::~FileCacheStore() {

ICacheStore::try_preadv_result FileCacheStore::try_preadv2(const struct iovec *iov, int iovcnt,
off_t offset, int flags) {
auto lruEntry = static_cast<FileCachePool::LruEntry *>(iterator_->second.get());
photon::scoped_rwlock rl(lruEntry->rw_lock_, photon::RLOCK);
photon::scoped_rwlock rl(rw_lock_, photon::RLOCK);
return this->ICacheStore::try_preadv2(iov, iovcnt, offset, flags);
}

Expand All @@ -70,8 +69,8 @@ ssize_t FileCacheStore::do_pwritev(const struct iovec *iov, int iovcnt, off_t of
{
ssize_t ret;
iovector_view view((iovec*)iov, iovcnt);
auto lruEntry = static_cast<FileCachePool::LruEntry *>(iterator_->second.get());
photon::scoped_rwlock rl(lruEntry->rw_lock_, photon::RLOCK);
auto lruEntry = iterator_->second.get();
photon::scoped_rwlock rl(rw_lock_, photon::RLOCK);
if (!lruEntry->truncate_done) {
// May repeated ftruncate() here, but it doesn't matter
ret = localFile_->ftruncate(actual_size_);
Expand Down
4 changes: 4 additions & 0 deletions fs/cache/full_file_cache/cache_store.h
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,8 @@ class FileCacheStore : public photon::fs::ICacheStore {

int fstat(struct stat *buf) override;

photon::rwlock &rw_lock() { return rw_lock_; }

protected:
bool cacheIsFull();

Expand All @@ -70,6 +72,8 @@ class FileCacheStore : public photon::fs::ICacheStore {
FileIterator iterator_;
RangeLock rangeLock_;

photon::rwlock rw_lock_;

ssize_t do_pwritev(const struct iovec *iov, int iovcnt, off_t offset);
};

Expand Down
11 changes: 9 additions & 2 deletions fs/cache/full_file_cache/quota_pool.cpp
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Expand Up @@ -194,8 +194,11 @@ int QuotaFilePool::evict(std::string_view filename) {
const auto& filePath = fileIter->first;
int err;
auto lruEntry = static_cast<QuotaLruEntry*>(fileIter->second.get());

auto cacheStore = static_cast<FileCacheStore*>(open(filePath, O_RDWR, 0644));
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@lihuiba lihuiba Mar 19, 2026

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DEFER(cacheStore->release())

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@xiaoyang-hhh xiaoyang-hhh Mar 20, 2026

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done

DEFER(cacheStore->release());
{
photon::scoped_rwlock rl(lruEntry->rw_lock_, photon::WLOCK);
photon::scoped_rwlock rl(cacheStore->rw_lock(), photon::WLOCK);
lru.mark_key_cleared(lruEntry->QuotaLruIter);
err = mediaFs_->truncate(filePath.data(), 0);
if (err) {
Expand Down Expand Up @@ -234,15 +237,19 @@ void QuotaFilePool::dirEviction() {
auto lruEntry = static_cast<QuotaLruEntry*>(fileIter->second.get());
int err;
bool flags_dir_delete = false;

auto cacheStore = static_cast<FileCacheStore*>(open(fileName, O_RDWR, 0644));
DEFER(cacheStore->release());
{
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@lihuiba lihuiba Mar 19, 2026

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DEFER(cacheStore->release())

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@xiaoyang-hhh xiaoyang-hhh Mar 20, 2026

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done

photon::scoped_rwlock rl(lruEntry->rw_lock_, photon::WLOCK);
photon::scoped_rwlock rl(cacheStore->rw_lock(), photon::WLOCK);
if (lruEntry->openCount==0){
dir->lru.mark_key_cleared(lruEntry->QuotaLruIter);
} else {
dir->lru.access(lruEntry->QuotaLruIter);
}
err = mediaFs_->truncate(fileName.data(), 0);
}

if (err) {
ERRNO e;
LOG_ERROR("truncate(0) failed, name : `, ret : `, error code : `", fileName, err, e);
Expand Down
3 changes: 1 addition & 2 deletions fs/cache/full_file_cache/quota_pool.h
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Original file line number Diff line number Diff line change
Expand Up @@ -27,8 +27,6 @@ class QuotaFilePool : public FileCachePool {
QuotaFilePool(photon::fs::IFileSystem* mediaFs, uint64_t capacityInGB, uint64_t periodInUs,
uint64_t diskAvailInBytes, uint64_t refillUnit, int quotaDirLevel);

photon::fs::ICacheStore* do_open(std::string_view pathname, int flags, mode_t mode) override;

void updateDirLru(FileIterator iter);

bool dirSpaceIsFull(FileIterator iter);
Expand All @@ -42,6 +40,7 @@ class QuotaFilePool : public FileCachePool {
int evict(std::string_view filename) override;

protected:
photon::fs::ICacheStore* do_open(std::string_view pathname, int flags, mode_t mode) override;
void dirEviction();

bool afterFtrucate(FileIterator iter) override;
Expand Down
3 changes: 1 addition & 2 deletions fs/cache/full_file_cache/quota_store.cpp
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Expand Up @@ -56,8 +56,7 @@ ssize_t QuotaFileStore::do_pwritev2(const struct iovec *iov, int iovcnt, off_t o
}
ssize_t ret;
{
auto lruEntry = static_cast<FileCachePool::LruEntry*>(iterator_->second.get());
photon::scoped_rwlock wl(lruEntry->rw_lock_, photon::WLOCK);
photon::scoped_rwlock wl(rw_lock_, photon::WLOCK);
ret = localFile_->pwritev(iov, iovcnt, offset);
}
if (ret < 0 && ENOSPC == errno) {
Expand Down
4 changes: 2 additions & 2 deletions fs/cache/pool_store.h
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Expand Up @@ -108,8 +108,6 @@ namespace fs

void set_trans_func(CacheFnTransFunc fn_trans_func);

virtual ICacheStore* do_open(std::string_view filename, int flags, mode_t mode) = 0;

virtual int rename(std::string_view oldname, std::string_view newname) = 0;

virtual ssize_t list(const char* dirname, ListType type,
Expand Down Expand Up @@ -146,6 +144,8 @@ namespace fs
}

protected:
virtual ICacheStore* do_open(std::string_view filename, int flags, mode_t mode) = 0;

void* m_stores;
CacheFnTransFunc fn_trans_func;
void* m_thread_pool = nullptr;
Expand Down
38 changes: 38 additions & 0 deletions fs/cache/test/cache_test.cpp
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Expand Up @@ -676,6 +676,44 @@ TEST(CachePool, random_evict_file) {
if (cacheStore) cacheStore->release();
}

TEST(CachePool, open_same_file) {
std::string root = "/tmp/ease/cache/open_same_file/";
SetupTestDir(root);
auto mediaFs = new_localfs_adaptor(root.c_str(), ioengine_libaio);
auto alignFs = new_aligned_fs_adaptor(mediaFs, 4 * 1024, true, true);
auto cacheAllocator = new AlignedAlloc(4 * 1024);
auto roCachedFs = new_full_file_cached_fs(nullptr, alignFs, 1024 * 1024,
1, 1000 * 1000 * 1, 128ul * 1024 * 1024, cacheAllocator, 0);
auto cachePool = roCachedFs->get_pool();
DEFER({ delete cacheAllocator; delete roCachedFs; });

auto fileName = "/testDir/testfile";

uint64_t written = 0;
for (int j = 0; j < 5; j++) {
std::vector<ICacheStore*> cacheStores;
for (int i = 0; i < 10; i++) {
cacheStores.push_back(cachePool->open(fileName, O_CREAT | O_RDWR, 0644));
ASSERT_NE(nullptr, cacheStores.back());
}

const size_t bufSize = 1024 * 1024;
IOVector buffer(*cacheAllocator);
buffer.push_back(bufSize);

for (auto cacheStore : cacheStores) {
if (rand() % 2 == 0) {
cacheStore->release();
} else {
auto ret = cacheStore->do_pwritev2(buffer.iovec(), buffer.iovcnt(), written, 0);
EXPECT_EQ(ret, (ssize_t)bufSize);
written += ret;
cacheStore->release();
}
}
}
}

}
}
int main(int argc, char** argv) {
Expand Down
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