ClickHouse/programs/library-bridge/LibraryBridgeHandlers.h
Robert Schulze e0d5020a92
Add simple versioning to the *-bridge-to-server protocol
- In general, it is expected that clickhouse-*-bridges and
  clickhouse-server were build from the same source version (e.g. are
  upgraded "atomically"). If that is not the case, we should at least
  be able to detect the mismatch and abort.

- This commit adds a URL parameter "version", defined in a header shared
  by the server and bridges. The bridge returns an error in case of
  mismatch.

- The version is *not* send and checked for "ping" requests (used for
  handshake), only for regular requests send after handshake. This is
  because the internally thrown server-side exception due to HTTP
  failure does not propagate the exact HTTP error (it only stores the
  error as text), and as a result, the server-side handshake code
  simply retries in case of error with exponential backoff and finally
  fails with a "timeout error". This is reasonable as pings typically
  fail due to time out. However, without a rework of HTTP exceptions,
  version mismatch during ping would also appear as "timeout" which is
  too misleading. The behavior may be changed later if needed.

- Note that introducing a version parameter does not represent a
  protocol upgrade itself. Bridges older than the server will simply
  ignore the field. Only servers older than the bridges receive an error
  but such a situation should never occur in practice.
2022-08-08 19:40:37 +00:00

47 lines
1.6 KiB
C++

#pragma once
#include <Interpreters/Context.h>
#include <Server/HTTP/HTTPRequestHandler.h>
#include <Common/logger_useful.h>
#include "ExternalDictionaryLibraryHandler.h"
namespace DB
{
/// Handler for requests to Library Dictionary Source, returns response in RowBinary format.
/// When a library dictionary source is created, it sends 'extDict_libNew' request to library bridge (which is started on first
/// request to it, if it was not yet started). On this request a new sharedLibrayHandler is added to a
/// sharedLibraryHandlerFactory by a dictionary uuid. With 'extDict_libNew' request come: library_path, library_settings,
/// names of dictionary attributes, sample block to parse block of null values, block of null values. Everything is
/// passed in binary format and is urlencoded. When dictionary is cloned, a new handler is created.
/// Each handler is unique to dictionary.
class ExternalDictionaryLibraryBridgeRequestHandler : public HTTPRequestHandler, WithContext
{
public:
ExternalDictionaryLibraryBridgeRequestHandler(size_t keep_alive_timeout_, ContextPtr context_);
void handleRequest(HTTPServerRequest & request, HTTPServerResponse & response) override;
private:
static constexpr inline auto FORMAT = "RowBinary";
Poco::Logger * log;
size_t keep_alive_timeout;
};
class ExternalDictionaryLibraryBridgeExistsHandler : public HTTPRequestHandler, WithContext
{
public:
ExternalDictionaryLibraryBridgeExistsHandler(size_t keep_alive_timeout_, ContextPtr context_);
void handleRequest(HTTPServerRequest & request, HTTPServerResponse & response) override;
private:
const size_t keep_alive_timeout;
Poco::Logger * log;
};
}