erl_threadpool.h

/*
 * Copyright (C) 2018 Cray Computer GmbH
 *
 * 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.
 *
 * 3. Neither the name of the copyright holder nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * 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
 * HOLDER 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.
 */

/* -*- mode:c -*- */
/** @file
 ** @brief Thread pool abstraction
 **
 **/
/** status codes */
#ifndef ERL_THREADPOOL_H_
#define ERL_THREADPOOL_H_ 1

#include "erl_status.h"
#include <stddef.h>

struct erl_threadpool_;
/** A threadpool handle */
typedef struct erl_threadpool_ *erl_threadpool;

/** scheduling strategy of threads in pool */
enum erl_threadpool_type {
  ERL_SCHED_DEFAULT = 1,
  ERL_SCHED_FIFO    = 1,
  ERL_SCHED_LIFO       ,
  ERL_SCHED_RANDOM     ,
  ERL_sched__MAX
};
enum erl_threadpool_cpubind {
  ERL_TP_BIND_NONE        = 0, /**< no CPU binding, let threading runtime decide */
  ERL_TP_BIND_FIXED       = 1, /**< bind threads to specified cpu IDs */
  ERL_TP_BIND_NUMA_RR_1   = 2, /**< bind threads to one fixed CPU per NUMA domain, round-robin */
  ERL_TP_BIND_NUMA_RR_ALL = 3, /**< bind threads to a CPU per NUMA domain, round robin, choosing a fresh CPU each round (as long as feasible) */
  ERL_tp_cpubind__max
};

/** attributes for the threads in the threadpool */
struct erl_threadpool_attr {
  size_t stacksize;                    /**< per-thread stack size */
  enum erl_threadpool_type type;       /**< scheduling type */
  enum erl_threadpool_cpubind bind;  /**< the desired CPU binding for threads in the pool */ 
  /** thread to CPU binding map: 
   * for NONE:   ignored
   * for FIXED:  must specify a CPU ID for each of the threads (as specified in the @ref num_threads argument to @ref erl_threadpool_create() call)
   * for RR_1:   must specify the desired CPU ID in each NUMA domain; -1 for 'don't care'. Thus must have as many entries as visible numa domains.
   * for RR_ALL: ignored
   */
  int bindings[];                     
};

int
erl__get_binding_error(const struct erl_threadpool_attr *attr, int nnodes, int ncpus, int tid);
int
erl__get_binding_index_fixed(const struct erl_threadpool_attr *attr, int nnodes, int ncpus, int tid);
int
erl__get_binding_index_rr1(const struct erl_threadpool_attr *attr, int nnodes, int ncpus, int tid);
int
erl__get_binding_index_rrall(const struct erl_threadpool_attr *attr, int nnodes, int ncpus, int tid);

static int (*const erl__get_binding_index[ERL_tp_cpubind__max]) 
    (const struct erl_threadpool_attr *attr, int nnodes, int ncpus, int tid) = {
  erl__get_binding_error,
  erl__get_binding_index_fixed,
  erl__get_binding_index_rr1,
  erl__get_binding_index_rrall
};

/** A structure describing a task to be run in a @ref erl_threadpool thread */
typedef struct erl_tp_task_ *erl_tp_task;

/** lock the task structure */
erl_status
erl_tp_task_lock(erl_tp_task task);

/** unlock the task structure */
erl_status
erl_tp_task_unlock(erl_tp_task task);

/** The task function: will be called with the closure specified at
 * task creation time, and the task container structure */
typedef erl_status(*erl_tp_task_func)(void* closure,
                                      erl_tp_task task);


/** default threadpool attributes */
#define ERL_TP_DEFAULT_ATTR NULL

/** Create a new threadpool
 **
 ** Create a new threadpool with up to @arg numthreads worker threads
 ** and attributes as specified by @arg attr. Use ERL_DEFAULT_ATTR to
 ** request default attributes.
 **
 ** @arg attr is safe to reuse after pool creation, it's not consumed
 ** by this function.
 **/
erl_status
erl_tp_create(size_t numthreads, const struct erl_threadpool_attr *attr,
              erl_threadpool *result_p);

/** Destroy a threadpool
 **/
erl_status
erl_tp_destroy(erl_threadpool pool);


/** Wait for completion of a job
 **
 ** blocks calling thread until @arg job is in ERL_TASK_COMPLETE state.
 **
 ** Upon ERL_OK return *closure is set to the closure passed to the
 ** job at job construction.
 **/
erl_status
erl_tp_wait(erl_tp_task job, void **closure);

/** construct a task */
erl_status
erl_tp_task_create(erl_tp_task_func function,
                 void *closure,
                 erl_tp_task *result_p);

/** destroy a task
 **
 ** destroys the container only, closure slot must be handled by caller.
 **/
erl_status
erl_tp_task_destroy(erl_tp_task task);

/** Submit a job */
erl_status
erl_tp_submit_task(erl_threadpool pool, erl_tp_task task);


#endif /* ERL_THREADPOOL_H_ */