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/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
/*
* Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
* University Research and Technology
* Corporation. All rights reserved.
* Copyright (c) 2004-2007 The University of Tennessee and The University
* of Tennessee Research Foundation. All rights
* reserved.
* Copyright (c) 2004-2006 High Performance Computing Center Stuttgart,
* University of Stuttgart. All rights reserved.
* Copyright (c) 2004-2005 The Regents of the University of California.
* All rights reserved.
* Copyright (c) 2007-2014 Cisco Systems, Inc. All rights reserved.
* Copyright (c) 2014-2016 Research Organization for Information Science
* and Technology (RIST). All rights reserved.
* Copyright (c) 2015-2016 Los Alamos National Security, LLC. All rights
* reserved.
* $COPYRIGHT$
*
* Additional copyrights may follow
*
* $HEADER$
*/
#if !defined(OPAL_THREAD_USAGE_H)
#define OPAL_THREAD_USAGE_H
#include "opal_config.h"
#include "opal/sys/atomic.h"
#include "opal/prefetch.h"
OPAL_DECLSPEC extern bool opal_uses_threads;
/**
* Check and see if the process is using multiple threads.
*
* @retval true If the process may have more than one thread.
* @retval false If the process only has a single thread.
*
* The value that this function returns is influenced by:
*
* - how MPI_INIT or MPI_INIT_THREAD was invoked,
* - what the final MPI thread level was determined to be,
* - whether the OMPI or MPI libraries are multi-threaded
*
* MPI_INIT and MPI_INIT_THREAD (specifically, back-end OMPI startup
* functions) invoke opal_set_using_threads() to influence the value of
* this function, depending on their situation. Some examples:
*
* - if MPI_INIT is invoked, and the ompi components in use are
* single-threaded, this value will be false.
*
* - if MPI_INIT_THREAD is invoked with MPI_THREAD_MULTIPLE, we have
* thread support, and the final thread level is determined to be
* MPI_THREAD_MULTIPLE, this value will be true.
*
* - if the process is a single-threaded OMPI executable (e.g., mpicc),
* this value will be false.
*
* Hence, this function will return false if there is guaranteed to
* only be one thread in the process. If there is even the
* possibility that we may have multiple threads, true will be
* returned.
*/
#define opal_using_threads() opal_uses_threads
/**
* Set whether the process is using multiple threads or not.
*
* @param have Boolean indicating whether the process is using
* multiple threads or not.
*
* @retval opal_using_threads The new return value from
* opal_using_threads().
*
* This function is used to influence the return value of
* opal_using_threads(). If configure detected that we have thread
* support, the return value of future invocations of
* opal_using_threads() will be the parameter's value. If configure
* detected that we have no thread support, then the retuen from
* opal_using_threads() will always be false.
*/
static inline bool opal_set_using_threads(bool have)
{
opal_uses_threads = have;
return opal_using_threads();
}
/**
* Use an atomic operation for increment/decrement if opal_using_threads()
* indicates that threads are in use by the application or library.
*/
#define OPAL_THREAD_DEFINE_ATOMIC_ADD(type, suffix) \
static inline type opal_thread_add_ ## suffix (volatile type *addr, type delta) \
{ \
if (OPAL_UNLIKELY(opal_using_threads())) { \
return opal_atomic_add_ ## suffix (addr, delta); \
} \
\
return (*addr += delta); \
}
#define OPAL_THREAD_DEFINE_ATOMIC_SUB(type, suffix) \
static inline type opal_thread_sub_ ## suffix (volatile type *addr, type delta) \
{ \
if (OPAL_UNLIKELY(opal_using_threads())) { \
return opal_atomic_sub_ ## suffix (addr, delta); \
} \
\
return (*addr -= delta); \
}
#define OPAL_THREAD_DEFINE_ATOMIC_CMPSET(type, addr_type, suffix) \
static inline bool opal_thread_cmpset_bool_ ## suffix (volatile addr_type *addr, type compare, type value) \
{ \
if (OPAL_UNLIKELY(opal_using_threads())) { \
return opal_atomic_cmpset_ ## suffix ((volatile type *) addr, compare, value); \
} \
\
if ((type) *addr == compare) { \
((type *) addr)[0] = value; \
return true; \
} \
\
return false; \
}
#define OPAL_THREAD_DEFINE_ATOMIC_SWAP(type, addr_type, suffix) \
static inline type opal_thread_swap_ ## suffix (volatile addr_type *ptr, type newvalue) \
{ \
if (opal_using_threads ()) { \
return opal_atomic_swap_ ## suffix ((volatile type *) ptr, newvalue); \
} \
\
type old = ((type *) ptr)[0]; \
((type *) ptr)[0] = newvalue; \
\
return old; \
}
OPAL_THREAD_DEFINE_ATOMIC_ADD(int32_t, 32)
OPAL_THREAD_DEFINE_ATOMIC_ADD(size_t, size_t)
OPAL_THREAD_DEFINE_ATOMIC_SUB(size_t, size_t)
OPAL_THREAD_DEFINE_ATOMIC_CMPSET(int32_t, int32_t, 32)
OPAL_THREAD_DEFINE_ATOMIC_CMPSET(void *, intptr_t, ptr)
OPAL_THREAD_DEFINE_ATOMIC_SWAP(int32_t, int32_t, 32)
OPAL_THREAD_DEFINE_ATOMIC_SWAP(void *, intptr_t, ptr)
#define OPAL_THREAD_ADD32 opal_thread_add_32
#define OPAL_ATOMIC_ADD32 opal_thread_add_32
#define OPAL_THREAD_ADD_SIZE_T opal_thread_add_size_t
#define OPAL_ATOMIC_ADD_SIZE_T opal_thread_add_size_t
#define OPAL_THREAD_SUB_SIZE_T opal_thread_sub_size_t
#define OPAL_ATOMIC_SUB_SIZE_T opal_thread_sub_size_t
#define OPAL_THREAD_CMPSET_32 opal_thread_cmpset_bool_32
#define OPAL_ATOMIC_CMPSET_32 opal_thread_cmpset_bool_32
#define OPAL_THREAD_CMPSET_PTR(x, y, z) opal_thread_cmpset_bool_ptr ((volatile intptr_t *) x, (void *) y, (void *) z)
#define OPAL_ATOMIC_CMPSET_PTR OPAL_THREAD_CMPSET_PTR
#define OPAL_THREAD_SWAP_32 opal_thread_swap_32
#define OPAL_ATOMIC_SWAP_32 opal_thread_swap_32
#define OPAL_THREAD_SWAP_PTR(x, y) opal_thread_swap_ptr ((volatile intptr_t *) x, (void *) y)
#define OPAL_ATOMIC_SWAP_PTR OPAL_THREAD_SWAP_PTR
/* define 64-bit macros is 64-bit atomic math is available */
#if OPAL_HAVE_ATOMIC_MATH_64
OPAL_THREAD_DEFINE_ATOMIC_ADD(int64_t, 64)
OPAL_THREAD_DEFINE_ATOMIC_CMPSET(int64_t, int64_t, 64)
OPAL_THREAD_DEFINE_ATOMIC_SWAP(int64_t, int64_t, 64)
#define OPAL_THREAD_ADD64 opal_thread_add_64
#define OPAL_ATOMIC_ADD64 opal_thread_add_64
#define OPAL_THREAD_CMPSET_64 opal_thread_cmpset_bool_64
#define OPAL_ATOMIC_CMPSET_64 opal_thread_cmpset_bool_64
#define OPAL_THREAD_SWAP_64 opal_thread_swap_64
#define OPAL_ATOMIC_SWAP_64 opal_thread_swap_64
#endif
#endif /* !defined(OPAL_THREAD_USAGE_H) */
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