jit_executor_component.h

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/*
 * Copyright (c) 2024, 2025, Oracle and/or its affiliates.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2.0,
 * as published by the Free Software Foundation.
 *
 * This program is designed to work with certain software (including
 * but not limited to OpenSSL) that is licensed under separate terms,
 * as designated in a particular file or component or in included license
 * documentation.  The authors of MySQL hereby grant you an additional
 * permission to link the program and your derivative works with the
 * separately licensed software that they have either included with
 * the program or referenced in the documentation.
 *
 * This program is distributed in the hope that it will be useful,  but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
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 *
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 */
 
#ifndef ROUTER_SRC_JIT_EXECUTOR_INCLUDE_MYSQLROUTER_JIT_EXECUTOR_COMPONENT_H_
#define ROUTER_SRC_JIT_EXECUTOR_INCLUDE_MYSQLROUTER_JIT_EXECUTOR_COMPONENT_H_
 
#include <chrono>
#include <memory>
#include <mutex>
#include <optional>
#include <string>
#include <tuple>
#include <unordered_map>
#include <utility>
#include <vector>
 
#include "mysqlrouter/jit_executor_context_handle.h"
#include "mysqlrouter/jit_executor_plugin_export.h"
#include "mysqlrouter/jit_executor_value.h"
#include "mysqlrouter/polyglot_file_system.h"
 
namespace jit_executor {
 
static const uint64_t k_default_pool_size = 8;
 
struct GlobalConfig {
  bool operator==(const GlobalConfig &o) const {
    return std::tie(maximum_ram_size, maximum_idle_time, default_pool_size) ==
           std::tie(o.maximum_ram_size, o.maximum_idle_time,
                    o.default_pool_size);
  }
 
  std::optional<uint64_t> maximum_ram_size;
  std::optional<uint64_t> maximum_idle_time;
  uint64_t default_pool_size = k_default_pool_size;
};
 
struct ServiceHandlerConfig {
  std::shared_ptr<shcore::polyglot::IFile_system> fs;
  std::vector<std::string> module_files;
  shcore::Dictionary_t globals;
  std::optional<uint64_t> pool_size;
  uint64_t default_pool_size = k_default_pool_size;
  std::optional<uint64_t> max_heap_size;
};
 
/** Interface defining central location for the handlers associated to a
 * database service
 */
class IServiceHandlers {
 public:
  virtual ~IServiceHandlers() = default;
  virtual std::shared_ptr<IContextHandle> get_context(
      const std::string &debug_port = "") = 0;
 
  virtual void release_debug_context() = 0;
 
  virtual bool init() = 0;
  virtual void teardown() = 0;
 
  virtual std::chrono::seconds idle_time() const = 0;
  virtual uint64_t pool_size() const = 0;
 
  virtual void set_max_heap_size(uint64_t) = 0;
  virtual void set_default_pool_size(uint64_t) = 0;
};
 
/**
 * Registry of graal contexts to be used by each service.
 *
 * NOTE: The original idea, was to have a pool of contexts on which the service
 * module files would be loaded once and then shared across the contexts in the
 * pool. The script end points would be getting a context from the pool use it
 * and the release it. However, the main pre-requisite for that is that the
 * context could be reset to the original state, which is NOT possible in Graal.
 *
 * Suggestion from the Graal Team
 *
 * By default, each context would internally create an engine which would hold
 * the resources used in the context. However, it is possible to use a common
 * engine to enable the sharing of the resources  across contexts (i.e.
 * including parsed source code). Following this approach the context pool is
 * not needed since we would simply create/release the context on demand and it
 * would use the shared resources from the engine.
 *
 * Even this is the current implementation, expectation was that the module
 * files would be loaded only ONCE but that's not the case, they get reloaded on
 * every created context, even the shared engine is used.
 *
 * This class holds a registry of service ids vs ContextHandlers (who keep the
 * shared engine) and allows creating a context using the shared engine.
 */
class JIT_EXECUTOR_PLUGIN_EXPORT JitExecutorComponent {
 public:
  static JitExecutorComponent &get_instance();
  ~JitExecutorComponent();
 
  JitExecutorComponent(JitExecutorComponent const &) = delete;
  void operator=(JitExecutorComponent const &) = delete;
 
  JitExecutorComponent(JitExecutorComponent &&) = delete;
  void operator=(JitExecutorComponent &&) = delete;
 
  void stop_debug_context(const std::string &service_id);
 
  std::shared_ptr<IContextHandle> get_context(
      const std::string &service_id, const ServiceHandlerConfig &config,
      const std::string &debug_port = "", bool reset_context = false);
 
  void update_global_config(const std::string &options);
 
 private:
  JitExecutorComponent() = default;
  void update_active_contexts(
      const std::pair<std::string, std::shared_ptr<IServiceHandlers>>
          &replacement = {});
  std::mutex m_context_creation;
 
  GlobalConfig m_global_config;
 
  std::unordered_map<std::string, std::shared_ptr<IServiceHandlers>>
      m_service_context_handlers;
 
  std::vector<std::shared_ptr<IServiceHandlers>> m_inactive_context_handlers;
};
 
}  // namespace jit_executor
 
#endif  // ROUTER_SRC_JIT_EXECUTOR_INCLUDE_MYSQLROUTER_JIT_EXECUTOR_COMPONENT_H_