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diff --git a/lib/isc/include/isc/taskpool.h b/lib/isc/include/isc/taskpool.h
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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/taskpool.h
+ * \brief A task pool is a mechanism for sharing a small number of tasks
+ * among a large number of objects such that each object is
+ * assigned a unique task, but each task may be shared by several
+ * objects.
+ *
+ * Task pools are used to let objects that can exist in large
+ * numbers (e.g., zones) use tasks for synchronization without
+ * the memory overhead and unfair scheduling competition that
+ * could result from creating a separate task for each object.
+ */
+
+/***
+ *** Imports.
+ ***/
+
+#include <stdbool.h>
+
+#include <isc/lang.h>
+#include <isc/task.h>
+
+ISC_LANG_BEGINDECLS
+
+/*****
+***** Types.
+*****/
+
+typedef struct isc_taskpool isc_taskpool_t;
+
+/*****
+***** Functions.
+*****/
+
+isc_result_t
+isc_taskpool_create(isc_taskmgr_t *tmgr, isc_mem_t *mctx, unsigned int ntasks,
+		    unsigned int quantum, bool priv, isc_taskpool_t **poolp);
+/*%<
+ * Create a task pool of "ntasks" tasks, each with quantum
+ * "quantum".
+ *
+ * Requires:
+ *
+ *\li	'tmgr' is a valid task manager.
+ *
+ *\li	'mctx' is a valid memory context.
+ *
+ *\li	poolp != NULL && *poolp == NULL
+ *
+ * Ensures:
+ *
+ *\li	On success, '*taskp' points to the new task pool.
+ *
+ * Returns:
+ *
+ *\li	#ISC_R_SUCCESS
+ *\li	#ISC_R_NOMEMORY
+ *\li	#ISC_R_UNEXPECTED
+ */
+
+void
+isc_taskpool_gettask(isc_taskpool_t *pool, isc_task_t **targetp);
+/*%<
+ * Attach to a task from the pool.  Currently the next task is chosen
+ * from the pool at random.  (This may be changed in the future to
+ * something that guaratees balance.)
+ */
+
+int
+isc_taskpool_size(isc_taskpool_t *pool);
+/*%<
+ * Returns the number of tasks in the task pool 'pool'.
+ */
+
+isc_result_t
+isc_taskpool_expand(isc_taskpool_t **sourcep, unsigned int size, bool priv,
+		    isc_taskpool_t **targetp);
+
+/*%<
+ * If 'size' is larger than the number of tasks in the pool pointed to by
+ * 'sourcep', then a new taskpool of size 'size' is allocated, the existing
+ * tasks from are moved into it, additional tasks are created to bring the
+ * total number up to 'size', and the resulting pool is attached to
+ * 'targetp'.
+ *
+ * If 'size' is less than or equal to the tasks in pool 'source', then
+ * 'sourcep' is attached to 'targetp' without any other action being taken.
+ *
+ * In either case, 'sourcep' is detached.
+ *
+ * Requires:
+ *
+ * \li	'sourcep' is not NULL and '*source' is not NULL
+ * \li	'targetp' is not NULL and '*source' is NULL
+ *
+ * Ensures:
+ *
+ * \li	On success, '*targetp' points to a valid task pool.
+ * \li	On success, '*sourcep' points to NULL.
+ *
+ * Returns:
+ *
+ * \li	#ISC_R_SUCCESS
+ * \li	#ISC_R_NOMEMORY
+ */
+
+void
+isc_taskpool_destroy(isc_taskpool_t **poolp);
+/*%<
+ * Destroy a task pool.  The tasks in the pool are detached but not
+ * shut down.
+ *
+ * Requires:
+ * \li	'*poolp' is a valid task pool.
+ */
+
+ISC_LANG_ENDDECLS