diff --git a/common/workerpool.h b/common/workerpool.h
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+/* Copyright (C) 2013-2016, The Regents of The University of Michigan.
+All rights reserved.
+This software was developed in the APRIL Robotics Lab under the
+direction of Edwin Olson, ebolson@umich.edu. This software may be
+available under alternative licensing terms; contact the address above.
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+The views and conclusions contained in the software and documentation are those
+of the authors and should not be interpreted as representing official policies,
+either expressed or implied, of the Regents of The University of Michigan.
+*/
+
+#pragma once
+
+#include "zarray.h"
+
+typedef struct workerpool workerpool_t;
+
+// as a special case, if nthreads==1, no additional threads are
+// created, and workerpool_run will run synchronously.
+workerpool_t *workerpool_create(int nthreads);
+void workerpool_destroy(workerpool_t *wp);
+
+void workerpool_add_task(workerpool_t *wp, void (*f)(void *p), void *p);
+
+// runs all added tasks, waits for them to complete.
+void workerpool_run(workerpool_t *wp);
+
+// same as workerpool_run, except always single threaded. (mostly for debugging).
+void workerpool_run_single(workerpool_t *wp);
+
+int workerpool_get_nthreads(workerpool_t *wp);
+
+int workerpool_get_nprocs();