#include <u.h>#include <libc.h> Along nextid; Along	counter;Along	done0;Along	done1;long	val0;long	val1; intspawn(void (*f)(void*), void *p){	int pid; 	pid = rfork(RFMEM|RFPROC);	switch(pid){	case -1:		sysfatal("rfork");	case 0:		f(p);		exits("spawn");	default:		return pid;	}} voidinc(void *p){	int i; 	for(i = 0; i < 10000; i++)		aincl(p, 1);} voiddec(void *p){	int i; 	for(i = 0; i < 10000; i++)		aincl(p, -1);} voidcasinc(void *p){	int i;	long v; 	for(i = 0; i < 10000; i++) do{		v = agetl(p);	}while(!acasl(p, v, v+1));} voidcasdec(void *p){	int i;	long v; 	for(i = 0; i < 10000; i++) do{		v = agetl(p);	}while(!acasl(p, v, v-1));} voidtoggle0(void*){	val0 = 1;	aswapl(&done0, 1);	while(agetl(&done1) != 1)		/* wait */;	assert(val1 == 1);} voidtoggle1(void*){	val1 = 1;	aswapl(&done1, 1);	while(agetl(&done0) != 1)		/* wait */;	assert(val0 == 1);} voidmain(void){	Along l;	Avlong v;	Aptr p;	int i; 	/* smoke test: does it work at all */	aswapl(&l, 1);	assert(agetl(&l) == 1);	assert(aincl(&l, 1) == 2);	assert(aincl(&l, -1) == 1);	assert(acasl(&l, 42, 123) == 0);	assert(agetl(&l) == 1);	assert(aswapl(&l, 77) == 1);	assert(acasl(&l, 77, 42) == 1);	assert(agetl(&l) == 42); 	aswapv(&v, 1);	assert(agetv(&v) == 1);	assert(aincv(&v, 1) == 2);	assert(aincv(&v, -1) == 1);	assert(acasv(&v, 42, 123) == 0);	assert(agetv(&v) == 1);	assert(aswapv(&v, 77) == 1);	assert(acasv(&v, 77, 42) == 1);	assert(agetv(&v) == 42); 	aswapp(&p, &v);	assert(agetp(&p) == &v);	assert(acasp(&p, &l, &i) == 0);	assert(agetp(&p) == &v);	assert(acasp(&p, &v, &i) == 1);	assert(agetp(&p) == &i); 	/* do our counters look atomic */	for(i = 0; i < 10; i++){		spawn(inc, &counter);		spawn(dec, &counter);	}	for(i = 0; i < 10; i++){		free(wait());		free(wait());	}	assert(agetl(&counter) == 0); 	/* how about when cas'ing */	for(i = 0; i < 1000; i++){		spawn(casinc, &counter);		spawn(casdec, &counter);	}	for(i = 0; i < 1000; i++){		free(wait());		free(wait());	}	assert(agetl(&counter) == 0); 	/* do the atomics act as barriers? */	for(i = 0; i < 10000; i++){		spawn(toggle0, &counter);		spawn(toggle1, &counter);		free(wait());		free(wait());	}	assert(agetl(&counter) == 0);	exits(nil);}