diff options
Diffstat (limited to 'mysys/my_uuid.c')
| -rw-r--r-- | mysys/my_uuid.c | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/mysys/my_uuid.c b/mysys/my_uuid.c new file mode 100644 index 00000000000..3c3cd8836fc --- /dev/null +++ b/mysys/my_uuid.c @@ -0,0 +1,169 @@ +/* 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> + +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; + 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), (seed1 + now)+random()); + 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+ seed2 + 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). + */ + int4store(to, time_low); + int2store(to+4, time_mid); + int2store(to+6, time_hi_and_version); + bmove(to+8, uuid_suffix, sizeof(uuid_suffix)); +} |