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54 lines
1.7 KiB
C
54 lines
1.7 KiB
C
/*
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* Copyright (C) 2014-2015 Red Hat ; see COPYRIGHT for license
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*/
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#include <isc/task.h>
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#include <isc/util.h>
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#include "lock.h"
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/*
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* Lock BIND dispatcher and allow only single task to run.
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*
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* @warning
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* All calls to isc_task_beginexclusive() have to operate on the same task
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* otherwise it would not be possible to distinguish recursive locking
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* from real conflict on the dispatcher lock.
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* For this reason this wrapper function always works with inst->task.
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* As a result, this function have to be be called only from inst->task.
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*
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* Recursive locking is allowed. Auxiliary variable pointed to by "statep"
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* stores information if last run_exclusive_enter() operation really locked
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* something or if the lock was called recursively and was no-op.
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*
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* The pair (inst, state) used for run_exclusive_enter() has to be
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* used for run_exclusive_exit().
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*
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* @param[in] inst The instance with the only task which is allowed to run.
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* @param[in,out] statep Lock state: ISC_R_SUCCESS or ISC_R_LOCKBUSY
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*/
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void
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run_exclusive_enter(sample_instance_t *inst, isc_result_t *statep) {
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REQUIRE(statep != NULL);
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REQUIRE(*statep == ISC_R_IGNORE);
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*statep = isc_task_beginexclusive(inst->task);
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RUNTIME_CHECK(*statep == ISC_R_SUCCESS || *statep == ISC_R_LOCKBUSY);
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}
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/*
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* Exit task-exclusive mode.
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*
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* @param[in] inst The instance used for previous run_exclusive_enter() call.
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* @param[in] state Lock state as returned by run_exclusive_enter().
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*/
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void
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run_exclusive_exit(sample_instance_t *inst, isc_result_t state) {
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if (state == ISC_R_SUCCESS)
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isc_task_endexclusive(inst->task);
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else
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/* Unlocking recursive lock or the lock was never locked. */
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INSIST(state == ISC_R_LOCKBUSY || state == ISC_R_IGNORE);
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return;
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}
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