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155 | // Copyright (C) 2016-2021 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef CTRL_AGENT_PROCESS_H
#define CTRL_AGENT_PROCESS_H
#include <agent/ca_cfg_mgr.h>
#include <http/listener.h>
#include <process/d_process.h>
#include <vector><--- Include file: not found. Please note: Cppcheck does not need standard library headers to get proper results.
namespace isc {
namespace agent {
/// @brief Kea Control Agent Application Process
///
/// CtrlAgentProcess provides top level application logic for the Control
/// Agent, a process managing Kea servers.
///
/// The Control Agent receives JSON control commands over HTTP and forwards
/// the JSON commands to the respective Kea servers. The JSON command
/// includes a name of the server to which the command pertains. After
/// receiving a response from the Kea server it is sent back over HTTP
/// to the control API client.
///
/// Some commands are handled by the Control Agent process itself, rather than
/// forwarded to the Kea servers. An example of such command is the one that
/// instructs the agent to start a specific service.
class CtrlAgentProcess : public process::DProcessBase {
public:
/// @brief Constructor
///
/// @param name name is a text label for the process. Generally used
/// in log statements, but otherwise arbitrary.
/// @param io_service is the io_service used by the caller for
/// asynchronous event handling.
CtrlAgentProcess(const char* name, const asiolink::IOServicePtr& io_service);
/// @brief Destructor
virtual ~CtrlAgentProcess();<--- Destructor in derived class
/// @brief Initialize the Control Agent process.
///
/// This is invoked by the controller after command line arguments but
/// prior to configuration reception. The base class provides this method
/// as a place to perform any derivation-specific initialization steps
/// that are inappropriate for the constructor but necessary prior to
/// launch.
virtual void init();<--- Function in derived class
/// @brief Implements the process's event loop.
///
/// @throw DProcessBaseError if an operational error is encountered.
virtual void run();<--- Function in derived class
/// @brief Initiates the process's shutdown process.
///
/// This is last step in the shutdown event callback chain, that is
/// intended to notify the process it is to begin its shutdown process.
///
/// @param args an Element set of shutdown arguments (if any) that are
/// supported by the process derivation.
///
/// @return an Element that contains the results of argument processing,
/// consisting of an integer status value (0 means successful,
/// non-zero means failure), and a string explanation of the outcome.
///
/// @throw DProcessBaseError if an operational error is encountered.
virtual isc::data::ConstElementPtr
shutdown(isc::data::ConstElementPtr args);<--- Function in derived class
/// @brief Processes the given configuration.
///
/// This method may be called multiple times during the process lifetime.
/// Certainly once during process startup, and possibly later if the user
/// alters configuration. This method must not throw, it should catch any
/// processing errors and return a success or failure answer as described
/// below.
///
/// A usual problem related to the system reconfiguration is how to preserve
/// configuration integrity in case of errors. In this case, when the
/// HTTP listener's configuration is modified there is a need to close all
/// existing connections and gracefully shutdown the listener's instance.
/// This, however, makes it possible that the control agent looses
/// connectivity if opening a new listener is unsuccessful. In fact, this
/// is quite possible scenario when the user is setting up the listener to
/// use a restricted port range or non-existing IP address. In this case,
/// the configuration parser will not signal the problem because IP address
/// and/or port are syntactically correct.
///
/// This method deals with this problem by opening a new listener aside of
/// the currently running listener (if the new listener settings are
/// different than current settings). Both instances are held until the
/// CtrlAgentProcess::garbageCollectListeners is invoked, which
/// removes any listeners which are no longer used.
///
/// @param config_set a new configuration (JSON) for the process
/// @param check_only true if configuration is to be verified only, not applied
/// @return an Element that contains the results of configuration composed
/// of an integer status value (0 means successful, non-zero means failure),
/// and a string explanation of the outcome.
virtual isc::data::ConstElementPtr
configure(isc::data::ConstElementPtr config_set,<--- Function in derived class
bool check_only = false);
/// @brief Returns a pointer to the configuration manager.
CtrlAgentCfgMgrPtr getCtrlAgentCfgMgr();
/// @brief Returns a const pointer to the HTTP listener used by the process.
///
/// @return Const pointer to the currently used listener or null pointer if
/// we're not listening. In fact, the latter should never be the case given
/// that we provide default listener configuration.
http::ConstHttpListenerPtr getHttpListener() const;
/// @brief Checks if the process is listening to the HTTP requests.
///
/// @return true if the process is listening.
bool isListening() const;
private:
/// @brief Removes listeners which are no longer in use.
///
/// This method should be called after executing
/// @ref CtrlAgentProcess::configure to remove listeners used previously
/// (no longer used because the listening address and port has changed as
// a result of the reconfiguration). If there are no listeners additional
/// to the one that is currently in use, the method has no effect.
/// This method is reused to remove all listeners at shutdown time.
///
/// @param leaving The number of listener to leave (default one).
void garbageCollectListeners(size_t leaving = 1);
/// @brief Polls all ready handlers and then runs one handler if none
/// handlers have been executed as a result of polling.
///
/// @return Number of executed handlers.
size_t runIO();
/// @brief Holds a list of pointers to the active listeners.
std::vector<http::HttpListenerPtr> http_listeners_;
};
/// @brief Defines a shared pointer to CtrlAgentProcess.
typedef boost::shared_ptr<CtrlAgentProcess> CtrlAgentProcessPtr;
}; // namespace isc::agent
}; // namespace isc
#endif // CTRL_AGENT_PROCESS_H
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