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/* SPDX-License-Identifier: GPL-2.0-or-later */
/** \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 = {BLI_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 not 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 collisions 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);
}
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