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/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* SPDX-License-Identifier: MPL-2.0 AND 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 https://mozilla.org/MPL/2.0/.
*
* See the COPYRIGHT file distributed with this work for additional
* information regarding copyright ownership.
*/
/*
* Copyright (C) Red Hat
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND AUTHORS DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#include "lock.h"
#include <isc/task.h>
#include <isc/util.h>
/*
* Lock BIND dispatcher and allow only single task to run.
*
* @warning
* All calls to isc_task_beginexclusive() have to operate on the same task
* otherwise it would not be possible to distinguish recursive locking
* from real conflict on the dispatcher lock.
* For this reason this wrapper function always works with inst->task.
* As a result, this function have to be be called only from inst->task.
*
* Recursive locking is allowed. Auxiliary variable pointed to by "statep"
* stores information if last run_exclusive_enter() operation really locked
* something or if the lock was called recursively and was no-op.
*
* The pair (inst, state) used for run_exclusive_enter() has to be
* used for run_exclusive_exit().
*
* @param[in] inst The instance with the only task which is allowed to
* run.
* @param[in,out] statep Lock state: ISC_R_SUCCESS or ISC_R_LOCKBUSY
*/
void
run_exclusive_enter(sample_instance_t *inst, isc_result_t *statep) {
REQUIRE(statep != NULL);
REQUIRE(*statep == ISC_R_IGNORE);
*statep = isc_task_beginexclusive(inst->task);
RUNTIME_CHECK(*statep == ISC_R_SUCCESS || *statep == ISC_R_LOCKBUSY);
}
/*
* Exit task-exclusive mode.
*
* @param[in] inst The instance used for previous run_exclusive_enter() call.
* @param[in] state Lock state as returned by run_exclusive_enter().
*/
void
run_exclusive_exit(sample_instance_t *inst, isc_result_t state) {
if (state == ISC_R_SUCCESS) {
isc_task_endexclusive(inst->task);
} else {
/* Unlocking recursive lock or the lock was never locked. */
INSIST(state == ISC_R_LOCKBUSY || state == ISC_R_IGNORE);
}
return;
}
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