mirror of
https://github.com/isc-projects/bind9.git
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eb8c9bdd55
This work cleans up the API which includes couple of things:
1. Make the isc_appctx_t type fully opaque
2. Protect all access to the isc_app_t members via stdatomics
3. sigwait() is part of POSIX.1, remove dead non-sigwait code
4. Remove unused code: isc_appctx_set{taskmgr,sockmgr,timermgr}
293 lines
7.4 KiB
C
293 lines
7.4 KiB
C
/*
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* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* See the COPYRIGHT file distributed with this work for additional
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* information regarding copyright ownership.
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*/
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#ifndef ISC_APP_H
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#define ISC_APP_H 1
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/*****
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***** Module Info
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*****/
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/*! \file isc/app.h
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* \brief ISC Application Support
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*
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* Dealing with program termination can be difficult, especially in a
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* multithreaded program. The routines in this module help coordinate
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* the shutdown process. They are used as follows by the initial (main)
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* thread of the application:
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*
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*\li isc_app_start(); Call very early in main(), before
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* any other threads have been created.
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*
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*\li isc_app_run(); This will post any on-run events,
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* and then block until application
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* shutdown is requested. A shutdown
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* request is made by calling
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* isc_app_shutdown(), or by sending
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* SIGINT or SIGTERM to the process.
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* After isc_app_run() returns, the
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* application should shutdown itself.
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*
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*\li isc_app_finish(); Call very late in main().
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*
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* Applications that want to use SIGHUP/isc_app_reload() to trigger reloading
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* should check the result of isc_app_run() and call the reload routine if
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* the result is ISC_R_RELOAD. They should then call isc_app_run() again
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* to resume waiting for reload or termination.
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*
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* Use of this module is not required. In particular, isc_app_start() is
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* NOT an ISC library initialization routine.
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*
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* This module also supports per-thread 'application contexts'. With this
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* mode, a thread-based application will have a separate context, in which
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* it uses other ISC library services such as tasks or timers. Signals are
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* not caught in this mode, so that the application can handle the signals
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* in its preferred way.
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*
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* \li MP:
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* Clients must ensure that isc_app_start(), isc_app_run(), and
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* isc_app_finish() are called at most once. isc_app_shutdown()
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* is safe to use by any thread (provided isc_app_start() has been
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* called previously).
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*
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* The same note applies to isc_app_ctxXXX() functions, but in this case
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* it's a per-thread restriction. For example, a thread with an
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* application context must ensure that isc_app_ctxstart() with the
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* context is called at most once.
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*
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* \li Reliability:
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* No anticipated impact.
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*
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* \li Resources:
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* None.
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*
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* \li Security:
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* No anticipated impact.
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*
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* \li Standards:
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* None.
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*/
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#include <stdbool.h>
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#include <isc/eventclass.h>
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#include <isc/lang.h>
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#include <isc/magic.h>
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#include <isc/result.h>
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/***
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*** Types
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***/
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typedef isc_event_t isc_appevent_t;
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#define ISC_APPEVENT_FIRSTEVENT (ISC_EVENTCLASS_APP + 0)
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#define ISC_APPEVENT_SHUTDOWN (ISC_EVENTCLASS_APP + 1)
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#define ISC_APPEVENT_LASTEVENT (ISC_EVENTCLASS_APP + 65535)
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/*%
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* This structure is actually just the common prefix of an application context
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* implementation's version of an isc_appctx_t.
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* \brief
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* Direct use of this structure by clients is forbidden. app implementations
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* may change the structure. 'magic' must be ISCAPI_APPCTX_MAGIC for any
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* of the isc_app_ routines to work. app implementations must maintain
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* all app context invariants.
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*/
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struct isc_appctx;
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ISC_LANG_BEGINDECLS
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isc_result_t
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isc_app_ctxstart(isc_appctx_t *ctx);
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isc_result_t
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isc_app_start(void);
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/*!<
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* \brief Start an ISC library application.
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*
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* Notes:
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* This call should be made before any other ISC library call, and as
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* close to the beginning of the application as possible.
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*
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* Requires:
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*\li 'ctx' is a valid application context (for app_ctxstart()).
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*/
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isc_result_t
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isc_app_ctxonrun(isc_appctx_t *ctx, isc_mem_t *mctx, isc_task_t *task,
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isc_taskaction_t action, void *arg);
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isc_result_t
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isc_app_onrun(isc_mem_t *mctx, isc_task_t *task, isc_taskaction_t action,
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void *arg);
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/*!<
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* \brief Request delivery of an event when the application is run.
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*
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* Requires:
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*\li isc_app_start() has been called.
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*\li 'ctx' is a valid application context (for app_ctxonrun()).
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*
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* Returns:
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* ISC_R_SUCCESS
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* ISC_R_NOMEMORY
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*/
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isc_result_t
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isc_app_ctxrun(isc_appctx_t *ctx);
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isc_result_t
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isc_app_run(void);
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/*!<
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* \brief Run an ISC library application.
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*
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* Notes:
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*\li The caller (typically the initial thread of an application) will
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* block until shutdown is requested. When the call returns, the
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* caller should start shutting down the application.
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*
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* Requires:
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*\li isc_app_[ctx]start() has been called.
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*
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* Ensures:
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*\li Any events requested via isc_app_onrun() will have been posted (in
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* FIFO order) before isc_app_run() blocks.
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*\li 'ctx' is a valid application context (for app_ctxrun()).
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*
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* Returns:
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*\li ISC_R_SUCCESS Shutdown has been requested.
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*\li ISC_R_RELOAD Reload has been requested.
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*/
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bool
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isc_app_isrunning(void);
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/*!<
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* \brief Return if the ISC library application is running.
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*
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* Returns:
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*\li true App is running.
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*\li false App is not running.
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*/
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void
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isc_app_ctxshutdown(isc_appctx_t *ctx);
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void
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isc_app_shutdown(void);
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/*!<
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* \brief Request application shutdown.
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*
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* Notes:
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*\li It is safe to call isc_app_shutdown() multiple times. Shutdown will
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* only be triggered once.
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*
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* Requires:
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*\li isc_app_[ctx]run() has been called.
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*\li 'ctx' is a valid application context (for app_ctxshutdown()).
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*
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* Returns:
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*\li ISC_R_SUCCESS
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*\li ISC_R_UNEXPECTED
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*/
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void
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isc_app_ctxsuspend(isc_appctx_t *ctx);
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/*!<
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* \brief This has the same behavior as isc_app_ctxsuspend().
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*/
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void
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isc_app_reload(void);
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/*!<
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* \brief Request application reload.
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*
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* Requires:
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*\li isc_app_run() has been called.
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*
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* Returns:
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*\li ISC_R_SUCCESS
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*\li ISC_R_UNEXPECTED
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*/
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void
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isc_app_ctxfinish(isc_appctx_t *ctx);
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void
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isc_app_finish(void);
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/*!<
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* \brief Finish an ISC library application.
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*
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* Notes:
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*\li This call should be made at or near the end of main().
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*
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* Requires:
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*\li isc_app_start() has been called.
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*\li 'ctx' is a valid application context (for app_ctxfinish()).
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*
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* Ensures:
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*\li Any resources allocated by isc_app_start() have been released.
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*/
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void
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isc_app_block(void);
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/*!<
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* \brief Indicate that a blocking operation will be performed.
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*
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* Notes:
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*\li If a blocking operation is in process, a call to isc_app_shutdown()
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* or an external signal will abort the program, rather than allowing
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* clean shutdown. This is primarily useful for reading user input.
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*
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* Requires:
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* \li isc_app_start() has been called.
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* \li No other blocking operations are in progress.
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*/
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void
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isc_app_unblock(void);
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/*!<
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* \brief Indicate that a blocking operation is complete.
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*
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* Notes:
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* \li When a blocking operation has completed, return the program to a
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* state where a call to isc_app_shutdown() or an external signal will
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* shutdown normally.
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*
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* Requires:
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* \li isc_app_start() has been called.
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* \li isc_app_block() has been called by the same thread.
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*/
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isc_result_t
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isc_appctx_create(isc_mem_t *mctx, isc_appctx_t **ctxp);
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/*!<
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* \brief Create an application context.
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*
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* Requires:
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*\li 'mctx' is a valid memory context.
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*\li 'ctxp' != NULL && *ctxp == NULL.
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*/
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void
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isc_appctx_destroy(isc_appctx_t **ctxp);
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/*!<
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* \brief Destroy an application context.
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*
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* Requires:
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*\li '*ctxp' is a valid application context.
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*
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* Ensures:
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*\li *ctxp == NULL.
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*/
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ISC_LANG_ENDDECLS
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#endif /* ISC_APP_H */
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