pthread_rwlock t1;
pthread_rwlock_wrlock(&t1);
pthread_rwlock t2 = t1;
what happend? is t2 locked or n开发者_如何学编程ot?
Nothing special happens. pthread_rwlock_t
(not pthread_rwlock
, AFAIK) is an opaque C struct. Copying the variable simply copies the struct, byte for byte.
At the Pthreads level, copying a pthread_rwlock_t
results in undefined behaviour. Don't do it.
A new copy is created. The below example may clear things
#include<stdio.h>
typedef struct
{
char a[8];
}example;
int main()
{
example s1, s2;
strcpy(s1.a,"Hi");
s2=s1;
printf("%s %s \n",s1.a,s2.a);
strcpy(s2.a,"There");
printf("%s %s \n",s1.a,s2.a);
return 0;
}
This will output:
Hi Hi
Hi There
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