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#include <Interpreters/Context.h>
#include <Storages/FileLog/ReadBufferFromFileLog.h>
#include <Common/Stopwatch.h>
#include <Common/logger_useful.h>
#include <algorithm>
#include <filesystem>
namespace DB
{
namespace ErrorCodes
{
extern const int CANNOT_READ_ALL_DATA;
}
ReadBufferFromFileLog::ReadBufferFromFileLog(
StorageFileLog & storage_,
size_t max_batch_size,
size_t poll_timeout_,
ContextPtr context_,
size_t stream_number_,
size_t max_streams_number_)
: ReadBuffer(nullptr, 0)
, log(&Poco::Logger::get("ReadBufferFromFileLog " + toString(stream_number_)))
, storage(storage_)
, batch_size(max_batch_size)
, poll_timeout(poll_timeout_)
, context(context_)
, stream_number(stream_number_)
, max_streams_number(max_streams_number_)
{
current = records.begin();
allowed = false;
}
bool ReadBufferFromFileLog::poll()
{
if (hasMorePolledRecords())
{
allowed = true;
return true;
}
auto new_records = pollBatch(batch_size);
if (new_records.empty())
{
buffer_status = BufferStatus::NO_RECORD_RETURNED;
LOG_TRACE(log, "No new records to read");
return false;
}
else
{
records = std::move(new_records);
current = records.begin();
LOG_TRACE(log, "Polled batch of {} records. ", records.size());
buffer_status = BufferStatus::POLLED_OK;
allowed = true;
return true;
}
}
ReadBufferFromFileLog::Records ReadBufferFromFileLog::pollBatch(size_t batch_size_)
{
Records new_records;
new_records.reserve(batch_size_);
readNewRecords(new_records, batch_size);
if (new_records.size() == batch_size_ || stream_out)
return new_records;
Stopwatch watch;
while (watch.elapsedMilliseconds() < poll_timeout && new_records.size() != batch_size_)
{
readNewRecords(new_records, batch_size);
/// All ifstrem reach end, no need to wait for timeout,
/// since file status can not be updated during a streamToViews
if (stream_out)
break;
}
return new_records;
}
void ReadBufferFromFileLog::readNewRecords(ReadBufferFromFileLog::Records & new_records, size_t batch_size_)
{
size_t need_records_size = batch_size_ - new_records.size();
size_t read_records_size = 0;
auto & file_infos = storage.getFileInfos();
size_t files_per_stream = file_infos.file_names.size() / max_streams_number;
size_t start = stream_number * files_per_stream;
size_t end = stream_number == max_streams_number - 1 ? file_infos.file_names.size() : (stream_number + 1) * files_per_stream;
for (size_t i = start; i < end; ++i)
{
const auto & file_name = file_infos.file_names[i];
auto & file_ctx = StorageFileLog::findInMap(file_infos.context_by_name, file_name);
if (file_ctx.status == StorageFileLog::FileStatus::NO_CHANGE)
continue;
auto & file_meta = StorageFileLog::findInMap(file_infos.meta_by_inode, file_ctx.inode);
if (!file_ctx.reader)
throw Exception(ErrorCodes::CANNOT_READ_ALL_DATA, "Ifstream for file {} is not initialized", file_meta.file_name);
auto & reader = file_ctx.reader.value();
StorageFileLog::assertStreamGood(reader);
Record record;
while (read_records_size < need_records_size)
{
/// Need to get offset before reading record from stream
auto offset = reader.tellg();
if (static_cast<UInt64>(offset) >= file_meta.last_open_end)
break;
record.offset = offset;
StorageFileLog::assertStreamGood(reader);
record.file_name = file_name;
std::getline(reader, record.data);
StorageFileLog::assertStreamGood(reader);
new_records.emplace_back(record);
++read_records_size;
}
UInt64 current_position = reader.tellg();
StorageFileLog::assertStreamGood(reader);
file_meta.last_writen_position = current_position;
/// stream reach to end
if (current_position == file_meta.last_open_end)
{
file_ctx.status = StorageFileLog::FileStatus::NO_CHANGE;
}
/// All ifstream reach end
if (i == end - 1 && (file_ctx.status == StorageFileLog::FileStatus::NO_CHANGE))
{
stream_out = true;
}
if (read_records_size == need_records_size)
{
break;
}
}
}
bool ReadBufferFromFileLog::nextImpl()
{
if (!allowed || !hasMorePolledRecords())
return false;
auto * new_position = const_cast<char *>(current->data.data());
BufferBase::set(new_position, current->data.size(), 0);
allowed = false;
current_file = current->file_name;
current_offset = current->offset;
++current;
return true;
}
}
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