ClickHouse/dbms/include/DB/IO/RemoteReadBuffer.h

#pragma once

#include <DB/IO/ReadBufferFromHTTP.h>
#include "ReadHelpers.h"

#define DEFAULT_REMOTE_READ_BUFFER_CONNECTION_TIMEOUT 1
#define DEFAULT_REMOTE_READ_BUFFER_RECEIVE_TIMEOUT 1800
#define DEFAULT_REMOTE_READ_BUFFER_SEND_TIMEOUT 1800

namespace DB
{

/** Позволяет читать файл с удалённого сервера через riod.
  */
class RemoteReadBuffer : public ReadBuffer
{
private:
	std::unique_ptr<ReadBufferFromHTTP> impl;

public:
	RemoteReadBuffer(
		const std::string & host,
		int port,
		const std::string & path,
		bool compress = true,
		size_t buffer_size = DBMS_DEFAULT_BUFFER_SIZE,
		const Poco::Timespan & connection_timeout = Poco::Timespan(DEFAULT_REMOTE_READ_BUFFER_CONNECTION_TIMEOUT, 0),
		const Poco::Timespan & send_timeout = Poco::Timespan(DEFAULT_REMOTE_READ_BUFFER_SEND_TIMEOUT, 0),
		const Poco::Timespan & receive_timeout = Poco::Timespan(DEFAULT_REMOTE_READ_BUFFER_RECEIVE_TIMEOUT, 0))
		: ReadBuffer(nullptr, 0)
	{
		ReadBufferFromHTTP::Params params = {
			std::make_pair("action", "read"),
			std::make_pair("path", path),
			std::make_pair("compress", (compress ? "true" : "false"))};

		impl = std::make_unique<ReadBufferFromHTTP>(host, port, params, buffer_size, connection_timeout, send_timeout, receive_timeout);
	}

	bool nextImpl()
	{
		if (!impl->next())
			return false;
		internal_buffer = impl->buffer();
		working_buffer = internal_buffer;
		return true;
	}

	/// Вернуть список имен файлов в директории.
	static std::vector<std::string> listFiles(
		const std::string & host,
		int port,
		const std::string & path,
		size_t timeout = 0)
	{
		ReadBufferFromHTTP::Params params = {
			std::make_pair("action", "list"),
			std::make_pair("path", path)};

		ReadBufferFromHTTP in(host, port, params, timeout);

		std::vector<std::string> files;
		while (!in.eof())
		{
			std::string s;
			readString(s, in);
			skipWhitespaceIfAny(in);
			files.push_back(s);
		}

		return files;
	}
};

}