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[Enhancement](hdfs-file-system) Change fs_handler ptr to shared_ptr and remove ref count operations. #34049

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Merged
morningman merged 1 commit into from
Apr 28, 2024
Merged

[Enhancement](hdfs-file-system) Change fs_handler ptr to shared_ptr and remove ref count operations. #34049

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39 changes: 13 additions & 26 deletions be/src/io/fs/hdfs_file_system.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -71,11 +71,11 @@ class HdfsFileSystemCache {

// This function is thread-safe
Status get_connection(const THdfsParams& hdfs_params, const std::string& fs_name,
HdfsFileSystemHandle** fs_handle);
std::shared_ptr<HdfsFileSystemHandle>* fs_handle);

private:
std::mutex _lock;
std::unordered_map<uint64, std::unique_ptr<HdfsFileSystemHandle>> _cache;
std::unordered_map<uint64, std::shared_ptr<HdfsFileSystemHandle>> _cache;

HdfsFileSystemCache() = default;

Expand Down Expand Up @@ -148,15 +148,7 @@ HdfsFileSystem::HdfsFileSystem(const THdfsParams& hdfs_params, std::string id,
}
}

HdfsFileSystem::~HdfsFileSystem() {
if (_fs_handle != nullptr) {
if (_fs_handle->from_cache) {
_fs_handle->dec_ref();
} else {
delete _fs_handle;
}
}
}
HdfsFileSystem::~HdfsFileSystem() = default;

Status HdfsFileSystem::connect_impl() {
RETURN_IF_ERROR(
Expand Down Expand Up @@ -384,10 +376,6 @@ Status HdfsFileSystem::download_impl(const Path& remote_file, const Path& local_
return local_writer->close();
}

HdfsFileSystemHandle* HdfsFileSystem::get_handle() {
return _fs_handle;
}

// ************* HdfsFileSystemCache ******************
int HdfsFileSystemCache::MAX_CACHE_HANDLE = 64;

Expand All @@ -406,7 +394,7 @@ Status HdfsFileSystemCache::_create_fs(const THdfsParams& hdfs_params, const std
void HdfsFileSystemCache::_clean_invalid() {
std::vector<uint64> removed_handle;
for (auto& item : _cache) {
if (item.second->invalid() && item.second->ref_cnt() == 0) {
if (item.second.use_count() == 1 && item.second->invalid()) {
removed_handle.emplace_back(item.first);
}
}
Expand All @@ -419,7 +407,7 @@ void HdfsFileSystemCache::_clean_oldest() {
uint64_t oldest_time = ULONG_MAX;
uint64 oldest = 0;
for (auto& item : _cache) {
if (item.second->ref_cnt() == 0 && item.second->last_access_time() < oldest_time) {
if (item.second.use_count() == 1 && item.second->last_access_time() < oldest_time) {
oldest_time = item.second->last_access_time();
oldest = item.first;
}
Expand All @@ -429,16 +417,16 @@ void HdfsFileSystemCache::_clean_oldest() {

Status HdfsFileSystemCache::get_connection(const THdfsParams& hdfs_params,
const std::string& fs_name,
HdfsFileSystemHandle** fs_handle) {
std::shared_ptr<HdfsFileSystemHandle>* fs_handle) {
uint64 hash_code = _hdfs_hash_code(hdfs_params, fs_name);
{
std::lock_guard<std::mutex> l(_lock);
auto it = _cache.find(hash_code);
if (it != _cache.end()) {
HdfsFileSystemHandle* handle = it->second.get();
std::shared_ptr<HdfsFileSystemHandle> handle = it->second;
if (!handle->invalid()) {
handle->inc_ref();
*fs_handle = handle;
handle->update_last_access_time();
*fs_handle = std::move(handle);
return Status::OK();
}
// fs handle is invalid, erase it.
Expand All @@ -455,13 +443,12 @@ Status HdfsFileSystemCache::get_connection(const THdfsParams& hdfs_params,
_clean_oldest();
}
if (_cache.size() < MAX_CACHE_HANDLE) {
std::unique_ptr<HdfsFileSystemHandle> handle =
std::make_unique<HdfsFileSystemHandle>(hdfs_fs, true);
handle->inc_ref();
*fs_handle = handle.get();
auto handle = std::make_shared<HdfsFileSystemHandle>(hdfs_fs, true);
handle->update_last_access_time();
*fs_handle = handle;
_cache[hash_code] = std::move(handle);
} else {
*fs_handle = new HdfsFileSystemHandle(hdfs_fs, false);
*fs_handle = std::make_shared<HdfsFileSystemHandle>(hdfs_fs, false);
}
}
return Status::OK();
Expand Down
26 changes: 7 additions & 19 deletions be/src/io/fs/hdfs_file_system.h
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Original file line number Diff line number Diff line change
Expand Up @@ -45,13 +45,11 @@ class HdfsFileSystemHandle {
HdfsFileSystemHandle(hdfsFS fs, bool cached)
: hdfs_fs(fs),
from_cache(cached),
_ref_cnt(0),
_create_time(_now()),
_last_access_time(0),
_invalid(false) {}

~HdfsFileSystemHandle() {
DCHECK(_ref_cnt == 0) << _ref_cnt;
if (hdfs_fs != nullptr) {
// DO NOT call hdfsDisconnect(), or we will meet "Filesystem closed"
// even if we create a new one
Expand All @@ -62,18 +60,14 @@ class HdfsFileSystemHandle {

int64_t last_access_time() { return _last_access_time; }

void inc_ref() {
_ref_cnt++;
_last_access_time = _now();
}

void dec_ref() {
_ref_cnt--;
_last_access_time = _now();
void update_last_access_time() {
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warning: method 'update_last_access_time' can be made const [readability-make-member-function-const]

Suggested change
void update_last_access_time() {
void update_last_access_time() const {

if (from_cache) {
_last_access_time = std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::system_clock::now().time_since_epoch())
.count();
}
}

int ref_cnt() { return _ref_cnt; }

bool invalid() { return _invalid; }

void set_invalid() { _invalid = true; }
Expand All @@ -84,8 +78,6 @@ class HdfsFileSystemHandle {
const bool from_cache;

private:
// the number of referenced client
std::atomic<int> _ref_cnt;
// For kerberos authentication, we need to save create time so that
// we can know if the kerberos ticket is expired.
std::atomic<uint64_t> _create_time;
Expand All @@ -109,8 +101,6 @@ class HdfsFileSystem final : public RemoteFileSystem {

~HdfsFileSystem() override;

HdfsFileSystemHandle* get_handle();

friend class HdfsFileHandleCache;

protected:
Expand Down Expand Up @@ -143,9 +133,7 @@ class HdfsFileSystem final : public RemoteFileSystem {
RuntimeProfile* profile);
const THdfsParams& _hdfs_params;
std::string _fs_name;
// do not use std::shared_ptr or std::unique_ptr
// _fs_handle is managed by HdfsFileSystemCache
HdfsFileSystemHandle* _fs_handle = nullptr;
std::shared_ptr<HdfsFileSystemHandle> _fs_handle = nullptr;
RuntimeProfile* _profile = nullptr;
};
} // namespace io
Expand Down