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/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* SPDX-License-Identifier: MPL-2.0
*
* 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 https://mozilla.org/MPL/2.0/.
*
* See the COPYRIGHT file distributed with this work for additional
* information regarding copyright ownership.
*/
#pragma once
/*****
***** Module Info
*****/
/*! \file isc/app.h
* \brief ISC Application Support
*
* Dealing with program termination can be difficult, especially in a
* multithreaded program. The routines in this module help coordinate
* the shutdown process. They are used as follows by the initial (main)
* thread of the application:
*
*\li isc_app_start(); Call very early in main(), before
* any other threads have been created.
*
*\li isc_app_run(); This will post any on-run events,
* and then block until application
* shutdown is requested. A shutdown
* request is made by calling
* isc_app_shutdown(), or by sending
* SIGINT or SIGTERM to the process.
* After isc_app_run() returns, the
* application should shutdown itself.
*
*\li isc_app_finish(); Call very late in main().
*
* Applications that want to use SIGHUP/isc_app_reload() to trigger reloading
* should check the result of isc_app_run() and call the reload routine if
* the result is ISC_R_RELOAD. They should then call isc_app_run() again
* to resume waiting for reload or termination.
*
* Use of this module is not required. In particular, isc_app_start() is
* NOT an ISC library initialization routine.
*
* This module also supports per-thread 'application contexts'. With this
* mode, a thread-based application will have a separate context, in which
* it uses other ISC library services such as tasks or timers. Signals are
* not caught in this mode, so that the application can handle the signals
* in its preferred way.
*
* \li MP:
* Clients must ensure that isc_app_start(), isc_app_run(), and
* isc_app_finish() are called at most once. isc_app_shutdown()
* is safe to use by any thread (provided isc_app_start() has been
* called previously).
*
* The same note applies to isc_app_ctxXXX() functions, but in this case
* it's a per-thread restriction. For example, a thread with an
* application context must ensure that isc_app_ctxstart() with the
* context is called at most once.
*
* \li Reliability:
* No anticipated impact.
*
* \li Resources:
* None.
*
* \li Security:
* No anticipated impact.
*
* \li Standards:
* None.
*/
#include <stdbool.h>
#include <isc/eventclass.h>
#include <isc/lang.h>
#include <isc/magic.h>
#include <isc/result.h>
#include <isc/types.h>
/***
*** Types
***/
typedef isc_event_t isc_appevent_t;
#define ISC_APPEVENT_FIRSTEVENT (ISC_EVENTCLASS_APP + 0)
#define ISC_APPEVENT_SHUTDOWN (ISC_EVENTCLASS_APP + 1)
#define ISC_APPEVENT_LASTEVENT (ISC_EVENTCLASS_APP + 65535)
ISC_LANG_BEGINDECLS
isc_result_t
isc_app_ctxstart(isc_appctx_t *ctx);
isc_result_t
isc_app_start(void);
/*!<
* \brief Start an ISC library application.
*
* Notes:
* This call should be made before any other ISC library call, and as
* close to the beginning of the application as possible.
*
* Requires:
*\li 'ctx' is a valid application context (for app_ctxstart()).
*/
isc_result_t
isc_app_ctxonrun(isc_appctx_t *ctx, isc_mem_t *mctx, isc_task_t *task,
isc_taskaction_t action, void *arg);
isc_result_t
isc_app_onrun(isc_mem_t *mctx, isc_task_t *task, isc_taskaction_t action,
void *arg);
/*!<
* \brief Request delivery of an event when the application is run.
*
* Requires:
*\li isc_app_start() has been called.
*\li 'ctx' is a valid application context (for app_ctxonrun()).
*
* Returns:
* ISC_R_SUCCESS
* ISC_R_NOMEMORY
*/
isc_result_t
isc_app_ctxrun(isc_appctx_t *ctx);
isc_result_t
isc_app_run(void);
/*!<
* \brief Run an ISC library application.
*
* Notes:
*\li The caller (typically the initial thread of an application) will
* block until shutdown is requested. When the call returns, the
* caller should start shutting down the application.
*
* Requires:
*\li isc_app_[ctx]start() has been called.
*
* Ensures:
*\li Any events requested via isc_app_onrun() will have been posted (in
* FIFO order) before isc_app_run() blocks.
*\li 'ctx' is a valid application context (for app_ctxrun()).
*
* Returns:
*\li ISC_R_SUCCESS Shutdown has been requested.
*\li ISC_R_RELOAD Reload has been requested.
*/
bool
isc_app_isrunning(void);
/*!<
* \brief Return if the ISC library application is running.
*
* Returns:
*\li true App is running.
*\li false App is not running.
*/
void
isc_app_ctxshutdown(isc_appctx_t *ctx);
void
isc_app_shutdown(void);
/*!<
* \brief Request application shutdown.
*
* Notes:
*\li It is safe to call isc_app_shutdown() multiple times. Shutdown will
* only be triggered once.
*
* Requires:
*\li isc_app_[ctx]run() has been called.
*\li 'ctx' is a valid application context (for app_ctxshutdown()).
*
* Returns:
*\li ISC_R_SUCCESS
*\li ISC_R_UNEXPECTED
*/
void
isc_app_ctxsuspend(isc_appctx_t *ctx);
/*!<
* \brief This has the same behavior as isc_app_ctxsuspend().
*/
void
isc_app_reload(void);
/*!<
* \brief Request application reload.
*
* Requires:
*\li isc_app_run() has been called.
*
* Returns:
*\li ISC_R_SUCCESS
*\li ISC_R_UNEXPECTED
*/
void
isc_app_ctxfinish(isc_appctx_t *ctx);
void
isc_app_finish(void);
/*!<
* \brief Finish an ISC library application.
*
* Notes:
*\li This call should be made at or near the end of main().
*
* Requires:
*\li isc_app_start() has been called.
*\li 'ctx' is a valid application context (for app_ctxfinish()).
*
* Ensures:
*\li Any resources allocated by isc_app_start() have been released.
*/
void
isc_app_block(void);
/*!<
* \brief Indicate that a blocking operation will be performed.
*
* Notes:
*\li If a blocking operation is in process, a call to isc_app_shutdown()
* or an external signal will abort the program, rather than allowing
* clean shutdown. This is primarily useful for reading user input.
*
* Requires:
* \li isc_app_start() has been called.
* \li No other blocking operations are in progress.
*/
void
isc_app_unblock(void);
/*!<
* \brief Indicate that a blocking operation is complete.
*
* Notes:
* \li When a blocking operation has completed, return the program to a
* state where a call to isc_app_shutdown() or an external signal will
* shutdown normally.
*
* Requires:
* \li isc_app_start() has been called.
* \li isc_app_block() has been called by the same thread.
*/
isc_result_t
isc_appctx_create(isc_mem_t *mctx, isc_appctx_t **ctxp);
/*!<
* \brief Create an application context.
*
* Requires:
*\li 'mctx' is a valid memory context.
*\li 'ctxp' != NULL && *ctxp == NULL.
*/
void
isc_appctx_destroy(isc_appctx_t **ctxp);
/*!<
* \brief Destroy an application context.
*
* Requires:
*\li '*ctxp' is a valid application context.
*
* Ensures:
*\li *ctxp == NULL.
*/
ISC_LANG_ENDDECLS
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