79 lines
2.5 KiB
C
79 lines
2.5 KiB
C
/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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/** \file
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* \ingroup bli
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*/
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#include "BLI_session_uuid.h"
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#include "BLI_utildefines.h"
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#include "atomic_ops.h"
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/* Special value which indicates the UUID has not been assigned yet. */
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#define BLI_SESSION_UUID_NONE 0
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static const SessionUUID global_session_uuid_none = {BLI_SESSION_UUID_NONE};
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/* Denotes last used UUID.
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* It might eventually overflow, and easiest is to add more bits to it. */
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static SessionUUID global_session_uuid = {BLI_SESSION_UUID_NONE};
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SessionUUID BLI_session_uuid_generate(void)
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{
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SessionUUID result;
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result.uuid_ = atomic_add_and_fetch_uint64(&global_session_uuid.uuid_, 1);
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if (!BLI_session_uuid_is_generated(&result)) {
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/* Happens when the UUID overflows.
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*
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* Just request the UUID once again, hoping that there are not a lot of high-priority threads
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* which will overflow the counter once again between the previous call and this one.
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*
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* NOTE: It is possible to have collisions after such overflow. */
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result.uuid_ = atomic_add_and_fetch_uint64(&global_session_uuid.uuid_, 1);
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}
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return result;
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}
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bool BLI_session_uuid_is_generated(const SessionUUID *uuid)
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{
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return !BLI_session_uuid_is_equal(uuid, &global_session_uuid_none);
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}
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bool BLI_session_uuid_is_equal(const SessionUUID *lhs, const SessionUUID *rhs)
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{
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return lhs->uuid_ == rhs->uuid_;
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}
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uint64_t BLI_session_uuid_hash_uint64(const SessionUUID *uuid)
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{
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return uuid->uuid_;
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}
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uint BLI_session_uuid_ghash_hash(const void *uuid_v)
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{
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const SessionUUID *uuid = (const SessionUUID *)uuid_v;
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return uuid->uuid_ & 0xffffffff;
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}
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bool BLI_session_uuid_ghash_compare(const void *lhs_v, const void *rhs_v)
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{
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const SessionUUID *lhs = (const SessionUUID *)lhs_v;
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const SessionUUID *rhs = (const SessionUUID *)rhs_v;
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return BLI_session_uuid_is_equal(lhs, rhs);
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}
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