forked from mongodb/mongo
/
oid.cpp
144 lines (122 loc) · 4.09 KB
/
oid.cpp
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// @file oid.cpp
/* Copyright 2009 10gen Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "pch.h"
#include "oid.h"
#include "util/atomic_int.h"
#include "../db/nonce.h"
BOOST_STATIC_ASSERT( sizeof(mongo::OID::MachineAndPid) == 5 );
BOOST_STATIC_ASSERT( sizeof(mongo::OID) == 12 );
namespace mongo {
static unsigned ourPid() {
unsigned pid;
#if defined(_WIN32)
pid = (unsigned short) GetCurrentProcessId();
#elif defined(__linux__)
pid = (unsigned short) getpid();
#else
pid = (unsigned short) security.getNonce();
#endif
return pid;
}
// machine # before folding in the process id
static OID::MachineAndPid ourMachine;
static void foldInPid(OID::MachineAndPid& x) {
unsigned p = ourPid();
x._pid ^= (unsigned short) p;
// when the pid is greater than 16 bits, let the high bits modulate the machine id field.
unsigned short& rest = (unsigned short &) x._machineNumber[1];
rest ^= p >> 16;
}
static OID::MachineAndPid __gen() {
unsigned long long n = security.getNonce();
OID::MachineAndPid x = ourMachine = (OID::MachineAndPid&) n;
foldInPid(x);
return x;
}
// after folding in the process id
static OID::MachineAndPid ourMachineAndPid = __gen();
void OID::regenMachineId() {
ourMachineAndPid = __gen();
}
inline bool operator!=(const OID::MachineAndPid& l, const OID::MachineAndPid& r) {
return l._pid != r._pid || l._machineNumber != r._machineNumber;
}
unsigned OID::getMachineId() {
unsigned char x[4];
x[0] = ourMachineAndPid._machineNumber[0];
x[1] = ourMachineAndPid._machineNumber[1];
x[2] = ourMachineAndPid._machineNumber[2];
x[3] = 0;
return (unsigned&) x[0];
}
void OID::justForked() {
MachineAndPid x = ourMachine;
// we let the random # for machine go into all 5 bytes of MachineAndPid, and then
// xor in the pid into _pid. this reduces the probability of collisions.
foldInPid(x);
ourMachineAndPid = __gen();
assert( x != ourMachineAndPid );
ourMachineAndPid = x;
}
void OID::init() {
static AtomicUInt inc = (unsigned) security.getNonce();
{
unsigned t = (unsigned) time(0);
unsigned char *T = (unsigned char *) &t;
_time[0] = T[3]; // big endian order because we use memcmp() to compare OID's
_time[1] = T[2];
_time[2] = T[1];
_time[3] = T[0];
}
_machineAndPid = ourMachineAndPid;
{
int new_inc = inc++;
unsigned char *T = (unsigned char *) &new_inc;
_inc[0] = T[2];
_inc[1] = T[1];
_inc[2] = T[0];
}
}
void OID::init( string s ){
assert( s.size() == 24 );
const char *p = s.c_str();
for( int i = 0; i < 12; i++ ) {
data[i] = fromHex(p);
p += 2;
}
}
void OID::init(Date_t date, bool max){
int time = (int) (date / 1000);
char* T = (char *) &time;
data[0] = T[3];
data[1] = T[2];
data[2] = T[1];
data[3] = T[0];
if (max)
*(long long*)(data + 4) = 0xFFFFFFFFFFFFFFFFll;
else
*(long long*)(data + 4) = 0x0000000000000000ll;
}
time_t OID::asTimeT(){
int time;
char* T = (char *) &time;
T[0] = data[3];
T[1] = data[2];
T[2] = data[1];
T[3] = data[0];
return time;
}
}