Differential D8433 Diff 27307 source/blender/blenlib/intern/session_uuid.c

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source/blender/blenlib/intern/session_uuid.c

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				/*
				* This program is free software; you can redistribute it and/or
				* modify it under the terms of the GNU General Public License
				* as published by the Free Software Foundation; either version 2
				* of the License, or (at your option) any later version.
				*
				* This program is distributed in the hope that it will be useful,
				* but WITHOUT ANY WARRANTY; without even the implied warranty of
				* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
				* GNU General Public License for more details.
				*
				* You should have received a copy of the GNU General Public License
				* along with this program; if not, write to the Free Software Foundation,
				* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
				*/

				/** \file
				* \ingroup bli
				*/

				#include "BLI_session_uuid.h"

				#include "BLI_utildefines.h"

				#include "atomic_ops.h"

				/* Special value which indicates the UUID has not been assigned yet. */
				#define BLI_SESSION_UUID_NONE 0

				static const SessionUUID global_session_uuid_none = {BLI_SESSION_UUID_NONE};

				/* Denotes last used UUID.
				* It might eventually overflow, and easiest is to add more bits to it. */
				static SessionUUID global_session_uuid = global_session_uuid_none;

				SessionUUID BLI_session_uuid_generate(void)
				{
				SessionUUID result;
				result.uuid_ = atomic_add_and_fetch_uint64(&global_session_uuid.uuid_, 1);
				if (!BLI_session_uuid_is_generated(&result)) {
				/* Happens when the UUID overflows.
				*
				* Just request the UUID once again, hoping that there are no a lot of high-priority threads
				* which will overflow the counter once again between the previous call and this one.
				*
				* NOTE: It is possible to have collissions after such overflow. */
				result.uuid_ = atomic_add_and_fetch_uint64(&global_session_uuid.uuid_, 1);
				}
				return result;
				}

				bool BLI_session_uuid_is_generated(const SessionUUID *uuid)
				{
				return !BLI_session_uuid_is_equal(uuid, &global_session_uuid_none);
				}

				bool BLI_session_uuid_is_equal(const SessionUUID lhs, const SessionUUID rhs)
				{
				return lhs->uuid_ == rhs->uuid_;
				}

				uint64_t BLI_session_uuid_hash_uint64(const SessionUUID *uuid)
				{
				return uuid->uuid_;
				}

				uint BLI_session_uuid_ghash_hash(const void *uuid_v)
				{
				const SessionUUID uuid = (const SessionUUID )uuid_v;
				return uuid->uuid_ & 0xffffffff;
				}

				bool BLI_session_uuid_ghash_compare(const void lhs_v, const void rhs_v)
				{
				const SessionUUID lhs = (const SessionUUID )lhs_v;
				const SessionUUID rhs = (const SessionUUID )rhs_v;
				return BLI_session_uuid_is_equal(lhs, rhs);
				}