ClickHouse/src/Storages/Cache/ExternalDataSourceCache.cpp

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#include <memory>
#include <unistd.h>
#include <functional>
#include <Core/BackgroundSchedulePool.h>
#include <Poco/Logger.h>
#include <base/logger_useful.h>
#include <base/sleep.h>
#include <base/errnoToString.h>
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#include <Common/ErrorCodes.h>
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#include <Common/ProfileEvents.h>
#include <Common/SipHash.h>
#include <Common/hex.h>
#include <Common/Exception.h>
#include <Storages/Cache/ExternalDataSourceCache.h>
#include <Storages/Cache/RemoteFileMetadataFactory.h>
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#include <IO/WriteHelpers.h>
namespace ProfileEvents
{
extern const Event ExternalDataSourceLocalCacheReadBytes;
}
namespace DB
{
namespace fs = std::filesystem;
namespace ErrorCodes
{
extern const int OK;
extern const int LOGICAL_ERROR;
extern const int NOT_INIT;
extern const int DISK_OVERFLOW;
}
RemoteReadBuffer::RemoteReadBuffer(size_t buff_size) : BufferWithOwnMemory<SeekableReadBufferWithSize>(buff_size)
{
}
RemoteReadBuffer::~RemoteReadBuffer()
{
if (file_cache_controller)
file_cache_controller->deallocFile(std::move(file_buffer));
}
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std::unique_ptr<ReadBuffer> RemoteReadBuffer::create(ContextPtr context, IRemoteFileMetadataPtr remote_file_metadata, std::unique_ptr<ReadBuffer> read_buffer, size_t buff_size)
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{
auto remote_path = remote_file_metadata->remote_path;
auto remote_read_buffer = std::make_unique<RemoteReadBuffer>(buff_size);
ErrorCodes::ErrorCode error;
std::tie(remote_read_buffer->file_cache_controller, read_buffer, error) = ExternalDataSourceCache::instance().createReader(context, remote_file_metadata, read_buffer);
if (remote_read_buffer->file_cache_controller == nullptr)
{
return read_buffer;
}
else
{
remote_read_buffer->file_buffer = remote_read_buffer->file_cache_controller->allocFile();
if (!remote_read_buffer->file_buffer)
throw Exception(ErrorCodes::LOGICAL_ERROR, "Create file readbuffer failed. {}",
remote_read_buffer->file_cache_controller->getLocalPath().string());
}
remote_read_buffer->remote_file_size = remote_file_metadata->file_size;
return remote_read_buffer;
}
bool RemoteReadBuffer::nextImpl()
{
auto start_offset = file_buffer->getPosition();
auto end_offset = start_offset + file_buffer->internalBuffer().size();
file_cache_controller->waitMoreData(start_offset, end_offset);
auto status = file_buffer->next();
if (status)
{
BufferBase::set(file_buffer->buffer().begin(),
file_buffer->buffer().size(),
file_buffer->offset());
ProfileEvents::increment(ProfileEvents::ExternalDataSourceLocalCacheReadBytes, file_buffer->available());
}
return status;
}
off_t RemoteReadBuffer::seek(off_t offset, int whence)
{
if (!file_buffer)
throw Exception(ErrorCodes::LOGICAL_ERROR, "Cannot call seek() in this buffer. It's a bug!");
/*
* Need to wait here. For example, the current file has been download at position X, but here we try to seek to
* postition Y (Y > X), it would fail.
*/
file_cache_controller->waitMoreData(offset, offset + file_buffer->internalBuffer().size());
auto ret = file_buffer->seek(offset, whence);
BufferBase::set(file_buffer->buffer().begin(),
file_buffer->buffer().size(),
file_buffer->offset());
return ret;
}
off_t RemoteReadBuffer::getPosition()
{
return file_buffer->getPosition();
}
ExternalDataSourceCache::ExternalDataSourceCache() = default;
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ExternalDataSourceCache::~ExternalDataSourceCache()
{
recover_task_holder->deactivate();
}
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ExternalDataSourceCache & ExternalDataSourceCache::instance()
{
static ExternalDataSourceCache instance;
return instance;
}
void ExternalDataSourceCache::recoverCachedFilesMetadata(
const fs::path & current_path,
size_t current_depth,
size_t max_depth)
{
if (current_depth >= max_depth)
{
std::vector<fs::path> invalid_paths;
for (auto const & dir : fs::directory_iterator{current_path})
{
String path = dir.path();
auto cache_controller = RemoteCacheController::recover(path);
if (!cache_controller)
{
invalid_paths.emplace_back(path);
continue;
}
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if (!lru_caches->trySet(path, cache_controller))
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{
invalid_paths.emplace_back(path);
}
}
for (auto & path : invalid_paths)
{
fs::remove_all(path);
}
return;
}
for (auto const & dir : fs::directory_iterator{current_path})
{
recoverCachedFilesMetadata(dir.path(), current_depth + 1, max_depth);
}
}
void ExternalDataSourceCache::recoverTask()
{
recoverCachedFilesMetadata(root_dir, 1, 2);
initialized = true;
LOG_INFO(log, "Recovered from directory:{}", root_dir);
}
void ExternalDataSourceCache::initOnce(
ContextPtr context,
const String & root_dir_, size_t limit_size_, size_t bytes_read_before_flush_)
{
std::lock_guard lock(mutex);
if (isInitialized())
{
throw Exception(ErrorCodes::LOGICAL_ERROR, "Cannot initialize ExternalDataSourceCache twice");
}
LOG_INFO(
log, "Initializing local cache for remote data sources. Local cache root path: {}, cache size limit: {}", root_dir_, limit_size_);
root_dir = root_dir_;
local_cache_bytes_read_before_flush = bytes_read_before_flush_;
lru_caches = std::make_unique<CacheType>(limit_size_);
/// create if root_dir not exists
if (!fs::exists(fs::path(root_dir)))
{
fs::create_directories(fs::path(root_dir));
}
recover_task_holder = context->getSchedulePool().createTask("recover local cache metadata for remote files", [this]{ recoverTask(); });
recover_task_holder->activateAndSchedule();
}
String ExternalDataSourceCache::calculateLocalPath(IRemoteFileMetadataPtr metadata) const
{
// add version into the full_path, and not block to read the new version
String full_path = metadata->getName() + ":" + metadata->remote_path
+ ":" + metadata->getVersion();
UInt128 hashcode = sipHash128(full_path.c_str(), full_path.size());
String hashcode_str = getHexUIntLowercase(hashcode);
return fs::path(root_dir) / hashcode_str.substr(0, 3) / hashcode_str;
}
std::tuple<RemoteCacheControllerPtr, std::unique_ptr<ReadBuffer>, ErrorCodes::ErrorCode>
ExternalDataSourceCache::createReader(ContextPtr context, IRemoteFileMetadataPtr remote_file_metadata, std::unique_ptr<ReadBuffer> & read_buffer)
{
// If something is wrong on startup, rollback to read from the original ReadBuffer
if (!isInitialized())
{
LOG_ERROR(log, "ExternalDataSourceCache has not been initialized");
return {nullptr, std::move(read_buffer), ErrorCodes::NOT_INIT};
}
auto remote_path = remote_file_metadata->remote_path;
const auto & last_modification_timestamp = remote_file_metadata->last_modification_timestamp;
auto local_path = calculateLocalPath(remote_file_metadata);
std::lock_guard lock(mutex);
auto cache = lru_caches->get(local_path);
if (cache)
{
// the remote file has been updated, need to redownload
if (!cache->isValid() || cache->isModified(remote_file_metadata))
{
LOG_TRACE(
log,
"Remote file ({}) has been updated. Last saved modification time: {}, actual last modification time: {}",
remote_path,
std::to_string(cache->getLastModificationTimestamp()),
std::to_string(last_modification_timestamp));
cache->markInvalid();
}
else
{
return {cache, nullptr, ErrorCodes::OK};
}
}
if (!fs::exists(local_path))
fs::create_directories(local_path);
// cache is not found or is invalid
auto new_cache = std::make_shared<RemoteCacheController>(remote_file_metadata, local_path, local_cache_bytes_read_before_flush);
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if (!lru_caches->trySet(local_path, new_cache))
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{
LOG_ERROR(log, "Insert the new cache failed. new file size:{}, current total size:{}",
remote_file_metadata->file_size,
lru_caches->weight());
return {nullptr, std::move(read_buffer), ErrorCodes::DISK_OVERFLOW};
}
new_cache->startBackgroundDownload(std::move(read_buffer), context->getSchedulePool());
return {new_cache, nullptr, ErrorCodes::OK};
}
}