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readerwriter.c
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readerwriter.c
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// a phase fair reader/writer lock implementation, version 2
// by Karl Malbrain, malbrain@cal.berkeley.edu
// 20 JUN 2016
#include <stdlib.h>
#include <stdint.h>
#include <memory.h>
#include <errno.h>
#include "readerwriter.h"
#ifndef _WIN32
#include <sched.h>
#else
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <process.h>
#include <intrin.h>
#endif
int NanoCnt[1];
int lock_spin(uint32_t* cnt);
void lock_sleep(int cnt);
#ifdef NEEDMUTEX
#ifndef _WIN32
#define pause() asm volatile("pause\n": : : "memory")
void lock_sleep (int cnt) {
struct timespec ts[1];
ts->tv_sec = 0;
ts->tv_nsec = cnt;
nanosleep(ts, NULL);
__sync_fetch_and_add(NanoCnt, 1);
}
int lock_spin (int *cnt) {
volatile int idx;
if (!*cnt)
*cnt = 8;
else if (*cnt < 1024 * 1024)
*cnt += *cnt / 4;
if (*cnt < 1024 )
for (idx = 0; idx < *cnt; idx++)
pause();
else
return 1;
return 0;
}
#else
void lock_sleep (int ticks) {
LARGE_INTEGER start[1], freq[1], next[1];
double conv, interval;
int idx;
QueryPerformanceFrequency(freq);
QueryPerformanceCounter(next);
conv = (double)freq->QuadPart / 1000000000;
for (idx = 0; idx < ticks; idx += (int)interval) {
*start = *next;
Sleep(0);
QueryPerformanceCounter(next);
interval = (next->QuadPart - start->QuadPart) / conv;
}
_InterlockedIncrement(NanoCnt);
}
int lock_spin (uint32_t *cnt) {
uint32_t idx;
if (!*cnt)
*cnt = 8;
if (*cnt < 1024 * 1024)
*cnt += *cnt / 4;
if (*cnt < 1024 )
for (idx = 0; idx < *cnt; idx++)
YieldProcessor();
else
return 1;
return 0;
}
#endif
// mutex implementation
#ifndef _WIN32
void mutex_lock(KMMutex* mutex) {
uint32_t spinCount = 0;
uint32_t prev;
while (__sync_lock_test_and_set(mutex->lock, 1))
while (*mutex->lock)
if (lock_spin (&spinCount))
lock_sleep(spinCount);
}
void mutex_unlock(KMMutex* mutex) {
#ifdef _WIN32
MemoryBarrier();
#else
__sync_synchronize();
#endif
*mutex->lock = 0;
}
#else
void mutex_lock(KMMutex* mutex) {
uint32_t spinCount = 0;
while (_InterlockedOr8(mutex->lock, 1))
while (*mutex->lock)
if (lock_spin(&spinCount))
lock_sleep(spinCount);
}
void mutex_unlock(KMMutex* mutex) {
#ifdef _WIN32
MemoryBarrier();
#else
__sync_synchronize();
#endif
*mutex->lock = 0;
}
#endif
#endif
// simple Phase-Fair FIFO rwlock
#if RWTYPE == 1
void initLock(RWLock* lock) {
memset(lock, 0, sizeof(*lock));
}
void writeLock (RWLock *lock)
{
Counter prev[1], next[1];
uint32_t spinCount = 0;
do {
*prev->bits = *lock->requests->bits;
*next->bits = *prev->bits;
next->writer[0]++;
# ifndef _WIN32
} while (!__sync_bool_compare_and_swap(lock->requests->bits, *prev->bits, *next->bits));
# else
} while (_InterlockedCompareExchange(lock->requests->bits, *next->bits, *prev->bits) != *prev->bits);
# endif
while (lock->completions->bits[0] != prev->bits[0])
if (lock_spin(&spinCount))
lock_sleep(spinCount);
}
void writeUnlock (RWLock *lock)
{
#ifdef _WIN32
MemoryBarrier();
#else
__sync_synchronize();
#endif
# ifndef _WIN32
__sync_fetch_and_add (lock->completions->writer, 1);
# else
_InterlockedExchangeAdd16(lock->completions->writer, 1);
# endif
}
void readLock (RWLock *lock)
{
uint32_t spinCount = 0;
Counter prev[1];
# ifndef _WIN32
*prev->bits = __sync_fetch_and_add (lock->requests->bits, RDINCR);
# else
*prev->bits = _InterlockedExchangeAdd(lock->requests->bits, RDINCR);
# endif
while (*lock->completions->writer != *prev->writer)
if (lock_spin(&spinCount))
lock_sleep(spinCount);
}
void readUnlock (RWLock *lock)
{
#ifdef _WIN32
MemoryBarrier();
#else
__sync_synchronize();
#endif
# ifndef _WIN32
__sync_fetch_and_add (lock->completions->reader, 1);
# else
_InterlockedExchangeAdd16(lock->completions->reader, 1);
# endif
}
#endif
// reader/writer lock implementation
// mutex based
#if RWTYPE == 2
void initLock(RWLock* lock) {
memset(lock, 0, sizeof(*lock));
}
void writeLock (RWLock *lock)
{
mutex_lock(lock->xcl);
mutex_lock(lock->wrt);
mutex_unlock(lock->xcl);
}
void writeUnlock (RWLock *lock)
{
mutex_unlock(lock->wrt);
}
void readLock (RWLock *lock)
{
mutex_lock(lock->xcl);
if (lock->readers[0]++ == 0)
mutex_lock(lock->wrt);
mutex_unlock(lock->xcl);
}
void readUnlock (RWLock *lock)
{
mutex_lock(lock->xcl);
if(--lock->readers[0] == 0)
mutex_unlock(lock->wrt);
mutex_unlock(lock->xcl);
}
#endif
#if RWTYPE == 3
void initLock(RWLock* lock) {
memset((void *)lock, 0, sizeof(*lock));
}
void writeLock (RWLock *lock)
{
uint32_t spinCount = 0;
uint16_t w, r, tix;
#ifndef _WIN32
tix = __sync_fetch_and_add (lock->ticket, 1);
#else
tix = _InterlockedExchangeAdd16 (lock->ticket, 1);
#endif
// wait for our ticket to come up
while( tix != lock->serving[0] )
if (lock_spin(&spinCount))
lock_sleep (spinCount);
// add the writer present bit and tix phase
spinCount = 0;
w = PRES | (tix & PHID);
#ifndef _WIN32
r = __sync_fetch_and_add (lock->rin, w);
#else
r = _InterlockedExchangeAdd16 (lock->rin, w);
#endif
while( r != *lock->rout )
if (lock_spin(&spinCount))
lock_sleep (spinCount);
}
void writeUnlock (RWLock *lock)
{
#ifdef _WIN32
MemoryBarrier();
#else
__sync_synchronize();
#endif
#ifndef _WIN32
__sync_fetch_and_and (lock->rin, ~MASK);
#else
_InterlockedAnd16 (lock->rin, ~MASK);
#endif
lock->serving[0]++;
}
void readLock (RWLock *lock)
{
uint32_t spinCount = 0;
uint16_t w;
#ifndef _WIN32
w = __sync_fetch_and_add (lock->rin, RINC) & MASK;
#else
w = _InterlockedExchangeAdd16 (lock->rin, RINC) & MASK;
#endif
if( w )
while( w == (*lock->rin & MASK) )
if (lock_spin(&spinCount))
lock_sleep (spinCount);
}
void readUnlock (RWLock *lock)
{
#ifdef _WIN32
MemoryBarrier();
#else
__sync_synchronize();
#endif
#ifndef _WIN32
__sync_fetch_and_add (lock->rout, RINC);
#else
_InterlockedExchangeAdd16 (lock->rout, RINC);
#endif
}
#endif
#ifdef STANDALONE
#include <stdio.h>
#ifdef _WIN32
double getCpuTime(int type)
{
FILETIME crtime[1];
FILETIME xittime[1];
FILETIME systime[1];
FILETIME usrtime[1];
SYSTEMTIME timeconv[1];
double ans = 0;
memset (timeconv, 0, sizeof(SYSTEMTIME));
switch( type ) {
case 0:
GetSystemTimeAsFileTime (xittime);
FileTimeToSystemTime (xittime, timeconv);
ans = (double)timeconv->wDayOfWeek * 3600 * 24;
break;
case 1:
GetProcessTimes (GetCurrentProcess(), crtime, xittime, systime, usrtime);
FileTimeToSystemTime (usrtime, timeconv);
break;
case 2:
GetProcessTimes (GetCurrentProcess(), crtime, xittime, systime, usrtime);
FileTimeToSystemTime (systime, timeconv);
break;
}
ans += (double)timeconv->wHour * 3600;
ans += (double)timeconv->wMinute * 60;
ans += (double)timeconv->wSecond;
ans += (double)timeconv->wMilliseconds / 1000;
return ans;
}
#else
#include <time.h>
#include <sys/resource.h>
double getCpuTime(int type)
{
struct rusage used[1];
struct timeval tv[1];
switch( type ) {
case 0:
gettimeofday(tv, NULL);
return (double)tv->tv_sec + (double)tv->tv_usec / 1000000;
case 1:
getrusage(RUSAGE_SELF, used);
return (double)used->ru_utime.tv_sec + (double)used->ru_utime.tv_usec / 1000000;
case 2:
getrusage(RUSAGE_SELF, used);
return (double)used->ru_stime.tv_sec + (double)used->ru_stime.tv_usec / 1000000;
}
return 0;
}
#endif
#ifndef _WIN32
unsigned char Array[256] __attribute__((aligned(64)));
#include <pthread.h>
pthread_rwlock_t lock0[1] = {PTHREAD_RWLOCK_INITIALIZER};
#else
__declspec(align(64)) unsigned char Array[256];
SRWLOCK lock0[1] = {SRWLOCK_INIT};
#endif
RWLock lock[1];
typedef struct {
int threadCnt;
int threadNo;
int loops;
int type;
int work;
} Arg;
void work (int validate, int usecs, int shuffle) {
volatile int cnt = usecs * 300;
int first, idx;
if (validate) {
while(shuffle && usecs--) {
first = Array[0];
for (idx = 0; idx < 255; idx++)
Array[idx] = Array[idx + 1];
Array[255] = first;
}
while (cnt--)
#ifndef _WIN32
__sync_fetch_and_add(&usecs, 1);
#else
_InterlockedIncrement(&usecs);
#endif
}
}
#ifdef _WIN32
UINT __stdcall launch(void *vals) {
#else
void *launch(void *vals) {
#endif
Arg *arg = (Arg *)vals;
int idx;
for( idx = 0; idx < arg->loops; idx++ ) {
#if RWTYPE == 0
#ifndef _WIN32
pthread_rwlock_rdlock(lock), work(arg->work, 1, 0), pthread_rwlock_unlock(lock);
#else
AcquireSRWLockShared(lock), work(arg->work, 1, 0), ReleaseSRWLockShared(lock);
#endif
#elif RWTYPE > 0
readLock(lock), work(arg->work, 1, 0), readUnlock(lock);
work(arg->work, 1,0);
#endif
if( (idx & 511) == 0)
#if RWTYPE == 0
#ifndef _WIN32
pthread_rwlock_wrlock(lock0), work(arg->work, 10, 1), pthread_rwlock_unlock(lock0);
#else
AcquireSRWLockExclusive(lock0), work(arg->work, 10, 1), ReleaseSRWLockExclusive(lock0);
#endif
#if RWTYPE > 0
writeLock(lock), work(arg->work, 10, 1), writeUnlock(lock);
#else
work(arg->work, 10,1);
#endif
#ifdef DEBUG
if (arg->type >= 0)
if (!(idx % 100000))
fprintf(stderr, "Thread %d loop %d\n", arg->threadNo, idx);
#endif
}
#ifdef DEBUG
if (arg->type >= 0)
fprintf(stderr, "Thread %d finished\n", arg->threadNo);
#endif
#ifndef _WIN32
return NULL;
#else
return 0;
#endif
}
int main (int argc, char **argv)
{
double start[3], elapsed, overhead[2][3];
int threadCnt, idx, phase;
Arg *args, base[1];
#ifndef WIN32
pthread_t *threads;
#else
DWORD thread_id[1];
HANDLE *threads;
#endif
if (argc < 2) {
fprintf(stderr, "Usage: %s #thrds lockType\n", argv[0]);
printf("sizeof RWLock: %d\n", (int)sizeof(lock));
threadCnt = 1;
LockType = 1;
}
else
{
threadCnt = atoi(argv[1]);
LockType = atoi(argv[2]);
}
// calculate non-lock timing
for(phase = 0; phase < 2; phase++) {
base->loops = 1000000 / threadCnt;;
base->threadCnt = 1;
base->threadNo = 0;
base->type = -1;
base->work = phase;
start[0] = getCpuTime(0);
start[1] = getCpuTime(1);
start[2] = getCpuTime(2);
launch(base);
overhead[phase][0] = getCpuTime(0) - start[0];
overhead[phase][1] = getCpuTime(1) - start[1];
overhead[phase][2] = getCpuTime(2) - start[2];
}
#ifndef _WIN32
threads = malloc(threadCnt * sizeof(pthread_t));
#else
threads = GlobalAlloc(GMEM_FIXED | GMEM_ZEROINIT, threadCnt * sizeof(HANDLE));
#endif
args = calloc(threadCnt, sizeof(Arg));
for(phase = 0; phase < 2; phase++) {
start[0] = getCpuTime(0);
start[1] = getCpuTime(1);
start[2] = getCpuTime(2);
for (idx = 0; idx < 256; idx++)
Array[idx] = idx;
for (idx = 0; idx < threadCnt; idx++) {
args[idx].loops = 1000000 / threadCnt;
args[idx].threadCnt = threadCnt;
args[idx].threadNo = idx;
args[idx].type = LockType;
args[idx].work = phase;
#ifdef _WIN32
do threads[idx] = (HANDLE)_beginthreadex(NULL, 131072, launch, (void *)(args + idx), 0, NULL);
while ((int64_t)threads[idx] == -1 && (SwitchToThread(), 1));
#else
if (pthread_create(threads + idx, NULL, launch, (void *)(args + idx)))
fprintf(stderr, "Unable to create thread %d, errno = %d\n", idx, errno);
#endif
}
// wait for termination
#ifndef _WIN32
for (idx = 0; idx < threadCnt; idx++)
pthread_join (threads[idx], NULL);
#else
for (idx = 0; idx < threadCnt; idx++) {
WaitForSingleObject (threads[idx], INFINITE);
CloseHandle(threads[idx]);
}
#endif
if (phase)
for( idx = 0; idx < 256; idx++)
if (Array[idx] != (unsigned char)(Array[(idx+1) % 256] - 1))
fprintf (stderr, "Array out of order\n");
if (!phase)
fprintf(stderr, "\nrwlock time/lock: \n");
else
fprintf(stderr, "\nrwlock moderate load: \n");
elapsed = getCpuTime(0) - start[0];
elapsed -= overhead[phase][0];
if (elapsed < 0)
elapsed = 0;
fprintf(stderr, " real %.3fus\n", elapsed);
elapsed = getCpuTime(1) - start[1];
elapsed -= overhead[phase][1];
if (elapsed < 0)
elapsed = 0;
fprintf(stderr, " user %.3fus\n", elapsed);
elapsed = getCpuTime(2) - start[2];
elapsed -= overhead[phase][2];
if (elapsed < 0)
elapsed = 0;
fprintf(stderr, " sys %.3fus\n", elapsed);
fprintf(stderr, " nanosleeps %d\n", NanoCnt[0]);
}
}
#endif
#endif