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/* Copyright (C) 2007 MySQL AB, Sergei Golubchik & Michael Widenius
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; version 2 of the License.
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
implements Universal Unique Identifiers (UUIDs), as in
DCE 1.1: Remote Procedure Call,
Open Group Technical Standard Document Number C706, October 1997,
(supersedes C309 DCE: Remote Procedure Call 8/1994,
which was basis for ISO/IEC 11578:1996 specification)
A UUID has the following structure:
Field NDR Data Type Octet # Note
time_low unsigned long 0-3 The low field of the
timestamp.
time_mid unsigned short 4-5 The middle field of
the timestamp.
time_hi_and_version unsigned short 6-7 The high field of the
timestamp multiplexed
with the version number.
clock_seq_hi_and_reserved unsigned small 8 The high field of the
clock sequence multi-
plexed with the variant.
clock_seq_low unsigned small 9 The low field of the
clock sequence.
node character 10-15 The spatially unique node
identifier.
*/
#include "mysys_priv.h"
#include <m_string.h>
#include <myisampack.h> /* mi_int2store, mi_int4store */
static my_bool my_uuid_inited= 0;
static struct my_rnd_struct uuid_rand;
static uint nanoseq;
static ulonglong uuid_time= 0;
static uchar uuid_suffix[2+6]; /* clock_seq and node */
#ifdef THREAD
pthread_mutex_t LOCK_uuid_generator;
#endif
/*
Number of 100-nanosecond intervals between
1582-10-15 00:00:00.00 and 1970-01-01 00:00:00.00
*/
#define UUID_TIME_OFFSET ((ulonglong) 141427 * 24 * 60 * 60 * 1000 * 10)
#define UUID_VERSION 0x1000
#define UUID_VARIANT 0x8000
/* Helper function */
static void set_clock_seq()
{
uint16 clock_seq= ((uint)(my_rnd(&uuid_rand)*16383)) | UUID_VARIANT;
mi_int2store(uuid_suffix, clock_seq);
}
/**
Init structures needed for my_uuid
@func my_uuid_init()
@param seed1 Seed for random generator
@param seed2 Seed for random generator
@note
Seed1 & seed2 should NOT depend on clock. This is to be able to
generate a random mac address according to UUID specs.
*/
void my_uuid_init(ulong seed1, ulong seed2)
{
uchar *mac= uuid_suffix+2;
ulonglong now;
if (my_uuid_inited)
return;
my_uuid_inited= 1;
now= my_getsystime();
nanoseq= 0;
if (my_gethwaddr(mac))
{
uint i;
/*
Generating random "hardware addr"
Specs explicitly specify that node identifier should NOT
correlate with a clock_seq value, so we use a separate
randominit() here.
*/
/* purecov: begin inspected */
my_rnd_init(&uuid_rand, (ulong) (seed2+ now/2), now+rand());
for (i=0; i < sizeof(mac); i++)
mac[i]= (uchar)(my_rnd(&uuid_rand)*255);
/* purecov: end */
}
my_rnd_init(&uuid_rand, (ulong) (seed1 + now), (ulong) (now/2+ getpid()));
set_clock_seq();
pthread_mutex_init(&LOCK_uuid_generator, MY_MUTEX_INIT_FAST);
}
/**
Create a global unique identifier (uuid)
@func my_uuid()
@param to Store uuid here. Must be of size MY_uuid_SIZE (16)
*/
void my_uuid(uchar *to)
{
ulonglong tv;
uint32 time_low;
uint16 time_mid, time_hi_and_version;
DBUG_ASSERT(my_uuid_inited);
pthread_mutex_lock(&LOCK_uuid_generator);
tv= my_getsystime() + UUID_TIME_OFFSET + nanoseq;
if (unlikely(tv < uuid_time))
set_clock_seq();
else if (unlikely(tv == uuid_time))
{
/* special protection for low-res system clocks */
nanoseq++;
tv++;
}
else
{
if (nanoseq && likely(tv-nanoseq >= uuid_time))
{
tv-=nanoseq;
nanoseq=0;
}
}
uuid_time=tv;
pthread_mutex_unlock(&LOCK_uuid_generator);
time_low= (uint32) (tv & 0xFFFFFFFF);
time_mid= (uint16) ((tv >> 32) & 0xFFFF);
time_hi_and_version= (uint16) ((tv >> 48) | UUID_VERSION);
/*
Note, that the standard does NOT specify byte ordering in
multi-byte fields. it's implementation defined (but must be
the same for all fields).
We use big-endian, so we can use memcmp() to compare UUIDs
and for straightforward UUID to string conversion.
*/
mi_int4store(to, time_low);
mi_int2store(to+4, time_mid);
mi_int2store(to+6, time_hi_and_version);
bmove(to+8, uuid_suffix, sizeof(uuid_suffix));
}
/**
Convert uuid to string representation
@func my_uuid2str()
@param guid uuid
@param s Output buffer.Must be at least MY_UUID_STRING_LENGTH+1 large.
*/
void my_uuid2str(const uchar *guid, char *s)
{
int i;
for (i=0; i < MY_UUID_SIZE; i++)
{
*s++= _dig_vec_lower[guid[i] >>4];
*s++= _dig_vec_lower[guid[i] & 15];
if(i == 4 || i == 6 || i == 8 || i == 10)
*s++= '-';
}
}
void my_uuid_end()
{
if (my_uuid_inited)
{
my_uuid_inited= 0;
pthread_mutex_destroy(&LOCK_uuid_generator);
}
}
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