#include "FileSegment.h"
#include
#include
#include
#include
#include
#include
namespace DB
{
namespace ErrorCodes
{
extern const int REMOTE_FS_OBJECT_CACHE_ERROR;
extern const int LOGICAL_ERROR;
}
FileSegment::FileSegment(
size_t offset_,
size_t size_,
const Key & key_,
IFileCache * cache_,
State download_state_)
: segment_range(offset_, offset_ + size_ - 1)
, download_state(download_state_)
, file_key(key_)
, cache(cache_)
#ifndef NDEBUG
, log(&Poco::Logger::get(fmt::format("FileSegment({}) : {}", getHexUIntLowercase(key_), range().toString())))
#else
, log(&Poco::Logger::get("FileSegment"))
#endif
{
if (download_state == State::DOWNLOADED)
reserved_size = downloaded_size = size_;
else if (download_state != State::EMPTY)
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Can create cell with either DOWNLOADED or EMPTY state");
}
FileSegment::State FileSegment::state() const
{
std::lock_guard segment_lock(mutex);
return download_state;
}
size_t FileSegment::getDownloadOffset() const
{
std::lock_guard segment_lock(mutex);
return range().left + getDownloadedSize(segment_lock);
}
size_t FileSegment::getDownloadedSize(std::lock_guard & /* segment_lock */) const
{
if (download_state == State::DOWNLOADED)
return downloaded_size;
std::lock_guard download_lock(download_mutex);
return downloaded_size;
}
String FileSegment::getCallerId()
{
return getCallerIdImpl(false);
}
String FileSegment::getCallerIdImpl(bool allow_non_strict_checking)
{
if (IFileCache::shouldBypassCache())
{
/// getCallerId() can be called from completeImpl(), which can be called from complete().
/// complete() is called from destructor of CachedReadBufferFromRemoteFS when there is no query id anymore.
/// Allow non strict checking in this case. This works correctly as if getCallerIdImpl() is called from destructor,
/// then we know that caller is not a downloader, because downloader is reset each nextImpl() call either
/// manually or via SCOPE_EXIT.
if (allow_non_strict_checking)
return "None";
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Cannot use cache without query id");
}
return CurrentThread::getQueryId().toString() + ":" + toString(getThreadId());
}
String FileSegment::getOrSetDownloader()
{
std::lock_guard segment_lock(mutex);
if (downloader_id.empty())
{
assert(download_state != State::DOWNLOADING);
if (download_state != State::EMPTY
&& download_state != State::PARTIALLY_DOWNLOADED)
return "None";
downloader_id = getCallerId();
download_state = State::DOWNLOADING;
}
else if (downloader_id == getCallerId())
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
"Attempt to set the same downloader for segment {} for the second time", range().toString());
return downloader_id;
}
void FileSegment::resetDownloader()
{
std::lock_guard segment_lock(mutex);
if (downloader_id.empty())
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "There is no downloader");
if (getCallerId() != downloader_id)
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Downloader can be reset only by downloader");
resetDownloaderImpl(segment_lock);
}
void FileSegment::resetDownloaderImpl(std::lock_guard & segment_lock)
{
if (downloaded_size == range().size())
setDownloaded(segment_lock);
else
download_state = State::PARTIALLY_DOWNLOADED;
downloader_id.clear();
}
String FileSegment::getDownloader() const
{
std::lock_guard segment_lock(mutex);
return downloader_id;
}
bool FileSegment::isDownloader() const
{
std::lock_guard segment_lock(mutex);
LOG_TEST(log, "Checking for current downloader. Caller: {}, downloader: {}, current state: {}", getCallerId(), downloader_id, stateToString(download_state));
return getCallerId() == downloader_id;
}
FileSegment::RemoteFileReaderPtr FileSegment::getRemoteFileReader()
{
if (!isDownloader())
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Only downloader can use remote filesystem file reader");
return remote_file_reader;
}
void FileSegment::setRemoteFileReader(RemoteFileReaderPtr remote_file_reader_)
{
if (!isDownloader())
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Only downloader can use remote filesystem file reader");
if (remote_file_reader)
throw Exception(ErrorCodes::LOGICAL_ERROR, "Remote file reader already exists");
remote_file_reader = remote_file_reader_;
}
void FileSegment::resetRemoteFileReader()
{
if (!isDownloader())
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Only downloader can use remote filesystem file reader");
if (!remote_file_reader)
throw Exception(ErrorCodes::LOGICAL_ERROR, "Remote file reader does not exist");
remote_file_reader.reset();
}
void FileSegment::write(const char * from, size_t size, size_t offset_)
{
if (!size)
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Writing zero size is not allowed");
if (availableSize() < size)
throw Exception(
ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
"Not enough space is reserved. Available: {}, expected: {}", availableSize(), size);
if (!isDownloader())
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
"Only downloader can do the downloading. (CallerId: {}, DownloaderId: {})",
getCallerId(), downloader_id);
if (downloaded_size == range().size())
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
"Attempt to write {} bytes to offset: {}, but current file segment is already fully downloaded",
size, offset_);
auto download_offset = range().left + downloaded_size;
if (offset_ != download_offset)
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
"Attempt to write {} bytes to offset: {}, but current download offset is {}",
size, offset_, download_offset);
if (!cache_writer)
{
if (downloaded_size > 0)
throw Exception(ErrorCodes::LOGICAL_ERROR,
"Cache writer was finalized (downloaded size: {}, state: {})",
downloaded_size, stateToString(download_state));
auto download_path = cache->getPathInLocalCache(key(), offset());
cache_writer = std::make_unique(download_path);
}
try
{
cache_writer->write(from, size);
std::lock_guard download_lock(download_mutex);
cache_writer->next();
downloaded_size += size;
}
catch (Exception & e)
{
std::lock_guard segment_lock(mutex);
auto info = getInfoForLogImpl(segment_lock);
e.addMessage("while writing into cache, info: " + info);
LOG_ERROR(log, "Failed to write to cache. File segment info: {}", info);
download_state = State::PARTIALLY_DOWNLOADED_NO_CONTINUATION;
cache_writer->finalize();
cache_writer.reset();
cv.notify_all();
throw;
}
assert(getDownloadOffset() == offset_ + size);
}
FileSegment::State FileSegment::wait()
{
std::unique_lock segment_lock(mutex);
if (downloader_id.empty())
return download_state;
if (download_state == State::EMPTY)
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Cannot wait on a file segment with empty state");
if (download_state == State::DOWNLOADING)
{
LOG_TEST(log, "{} waiting on: {}, current downloader: {}", getCallerId(), range().toString(), downloader_id);
assert(!downloader_id.empty());
assert(downloader_id != getCallerId());
cv.wait_for(segment_lock, std::chrono::seconds(60));
}
return download_state;
}
bool FileSegment::reserve(size_t size)
{
if (!size)
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Zero space reservation is not allowed");
{
std::lock_guard segment_lock(mutex);
auto caller_id = getCallerId();
if (downloader_id != caller_id)
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Space can be reserved only by downloader (current: {}, expected: {})", caller_id, downloader_id);
if (downloaded_size + size > range().size())
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
"Attempt to reserve space too much space ({}) for file segment with range: {} (downloaded size: {})",
size, range().toString(), downloaded_size);
assert(reserved_size >= downloaded_size);
}
/**
* It is possible to have downloaded_size < reserved_size when reserve is called
* in case previous downloader did not fully download current file_segment
* and the caller is going to continue;
*/
size_t free_space = reserved_size - downloaded_size;
size_t size_to_reserve = size - free_space;
std::lock_guard cache_lock(cache->mutex);
bool reserved = cache->tryReserve(key(), offset(), size_to_reserve, cache_lock);
if (reserved)
reserved_size += size;
return reserved;
}
void FileSegment::setDownloaded(std::lock_guard & /* segment_lock */)
{
download_state = State::DOWNLOADED;
is_downloaded = true;
if (cache_writer)
{
cache_writer->finalize();
cache_writer.reset();
remote_file_reader.reset();
}
}
void FileSegment::completeBatchAndResetDownloader()
{
std::lock_guard segment_lock(mutex);
bool is_downloader = downloader_id == getCallerId();
if (!is_downloader)
{
cv.notify_all();
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "File segment can be completed only by downloader");
}
resetDownloaderImpl(segment_lock);
LOG_TEST(log, "Complete batch. Current downloaded size: {}", downloaded_size);
cv.notify_all();
}
void FileSegment::complete(State state)
{
std::lock_guard cache_lock(cache->mutex);
std::lock_guard segment_lock(mutex);
bool is_downloader = downloader_id == getCallerId();
if (!is_downloader)
{
cv.notify_all();
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
"File segment can be completed only by downloader or downloader's FileSegmentsHodler");
}
if (state != State::DOWNLOADED
&& state != State::PARTIALLY_DOWNLOADED
&& state != State::PARTIALLY_DOWNLOADED_NO_CONTINUATION)
{
cv.notify_all();
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
"Cannot complete file segment with state: {}", stateToString(state));
}
download_state = state;
try
{
completeImpl(cache_lock, segment_lock);
}
catch (...)
{
if (!downloader_id.empty() && downloader_id == getCallerIdImpl(true))
downloader_id.clear();
cv.notify_all();
throw;
}
cv.notify_all();
}
void FileSegment::complete(std::lock_guard & cache_lock)
{
std::lock_guard segment_lock(mutex);
if (download_state == State::SKIP_CACHE || detached)
return;
if (download_state != State::DOWNLOADED && getDownloadedSize(segment_lock) == range().size())
setDownloaded(segment_lock);
if (download_state == State::DOWNLOADING || download_state == State::EMPTY)
{
/// Segment state can be changed from DOWNLOADING or EMPTY only if the caller is the
/// downloader or the only owner of the segment.
bool can_update_segment_state = downloader_id == getCallerIdImpl(true)
|| cache->isLastFileSegmentHolder(key(), offset(), cache_lock, segment_lock);
if (can_update_segment_state)
download_state = State::PARTIALLY_DOWNLOADED;
}
try
{
completeImpl(cache_lock, segment_lock, /* allow_non_strict_checking */true);
}
catch (...)
{
if (!downloader_id.empty() && downloader_id == getCallerIdImpl(true))
downloader_id.clear();
cv.notify_all();
throw;
}
cv.notify_all();
}
void FileSegment::completeImpl(std::lock_guard & cache_lock, std::lock_guard & segment_lock, bool allow_non_strict_checking)
{
bool is_last_holder = cache->isLastFileSegmentHolder(key(), offset(), cache_lock, segment_lock);
bool download_can_continue = !is_last_holder
&& download_state != State::DOWNLOADED
&& download_state != State::PARTIALLY_DOWNLOADED_NO_CONTINUATION;
if (!download_can_continue
&& (download_state == State::PARTIALLY_DOWNLOADED || download_state == State::PARTIALLY_DOWNLOADED_NO_CONTINUATION))
{
size_t current_downloaded_size = getDownloadedSize(segment_lock);
if (current_downloaded_size == 0)
{
download_state = State::SKIP_CACHE;
LOG_TEST(log, "Remove cell {} (nothing downloaded)", range().toString());
cache->remove(key(), offset(), cache_lock, segment_lock);
detached = true;
}
else if (is_last_holder)
{
/**
* Only last holder of current file segment can resize the cell,
* because there is an invariant that file segments returned to users
* in FileSegmentsHolder represent a contiguous range, so we can resize
* it only when nobody needs it.
*/
LOG_TEST(log, "Resize cell {} to downloaded: {}", range().toString(), current_downloaded_size);
cache->reduceSizeToDownloaded(key(), offset(), cache_lock, segment_lock);
detached = true;
}
if (cache_writer)
{
cache_writer->finalize();
cache_writer.reset();
remote_file_reader.reset();
}
}
if (!downloader_id.empty() && (downloader_id == getCallerIdImpl(allow_non_strict_checking) || is_last_holder))
{
LOG_TEST(log, "Clearing downloader id: {}, current state: {}", downloader_id, stateToString(download_state));
downloader_id.clear();
}
assertCorrectnessImpl(segment_lock);
}
String FileSegment::getInfoForLog() const
{
std::lock_guard segment_lock(mutex);
return getInfoForLogImpl(segment_lock);
}
String FileSegment::getInfoForLogImpl(std::lock_guard & segment_lock) const
{
WriteBufferFromOwnString info;
info << "File segment: " << range().toString() << ", ";
info << "state: " << download_state << ", ";
info << "downloaded size: " << getDownloadedSize(segment_lock) << ", ";
info << "downloader id: " << downloader_id << ", ";
info << "caller id: " << getCallerId();
return info.str();
}
String FileSegment::stateToString(FileSegment::State state)
{
switch (state)
{
case FileSegment::State::DOWNLOADED:
return "DOWNLOADED";
case FileSegment::State::EMPTY:
return "EMPTY";
case FileSegment::State::DOWNLOADING:
return "DOWNLOADING";
case FileSegment::State::PARTIALLY_DOWNLOADED:
return "PARTIALLY DOWNLOADED";
case FileSegment::State::PARTIALLY_DOWNLOADED_NO_CONTINUATION:
return "PARTIALLY DOWNLOADED NO CONTINUATION";
case FileSegment::State::SKIP_CACHE:
return "SKIP_CACHE";
}
}
void FileSegment::assertCorrectness() const
{
std::lock_guard segment_lock(mutex);
assertCorrectnessImpl(segment_lock);
}
void FileSegment::assertCorrectnessImpl(std::lock_guard & /* segment_lock */) const
{
assert(downloader_id.empty() == (download_state != FileSegment::State::DOWNLOADING));
assert(!downloader_id.empty() == (download_state == FileSegment::State::DOWNLOADING));
assert(download_state != FileSegment::State::DOWNLOADED || std::filesystem::file_size(cache->getPathInLocalCache(key(), offset())) > 0);
}
FileSegmentsHolder::~FileSegmentsHolder()
{
/// In CacheableReadBufferFromRemoteFS file segment's downloader removes file segments from
/// FileSegmentsHolder right after calling file_segment->complete(), so on destruction here
/// remain only uncompleted file segments.
IFileCache * cache = nullptr;
for (auto file_segment_it = file_segments.begin(); file_segment_it != file_segments.end();)
{
auto current_file_segment_it = file_segment_it++;
auto & file_segment = *current_file_segment_it;
if (!cache)
cache = file_segment->cache;
try
{
/// File segment pointer must be reset right after calling complete() and
/// under the same mutex, because complete() checks for segment pointers.
std::lock_guard cache_lock(cache->mutex);
file_segment->complete(cache_lock);
file_segments.erase(current_file_segment_it);
}
catch (...)
{
#ifndef NDEBUG
throw;
#else
tryLogCurrentException(__PRETTY_FUNCTION__);
#endif
}
}
}
String FileSegmentsHolder::toString()
{
String ranges;
for (const auto & file_segment : file_segments)
{
if (!ranges.empty())
ranges += ", ";
ranges += file_segment->range().toString();
}
return ranges;
}
}