c++ - assignment in pthreads application -

i have linux multithread application in c++. in application in class app offer variable status:

class app { ... typedef enum { asstop=0, asstart, asrestart, aswork, asclose } tappstatus; tappstatus status;  ... } 

all threads check status calling getstatus() function.

inline tappstatus app::getstatus(){ return status }; 

other functions of application can assign different values status variable calling setstatus() function , not use mutexes.

void app::setstatus( tappstatus astatus ){ status=astatus }; 

edit: threads use status in switch operator:

switch ( app::getstatus() ){ case asstop: ... case asstart: ... }; 

1. is assignment in case, atomic operation?
2. is correct code?

thanks.

there no portable way implement synchronized variables in c99 or c++03 , pthread library not provide 1 either. can:

• use c++0x <atomic> header (or c1x <stdatomic.h>). gcc support c++ if given -std=c++0x or -std=gnu++0x option since version 4.4.
• use linux-specific <linux/atomic.h> (this implementation used kernel, should usable userland well).
• use gcc-specific __sync_* builtin functions.
• use other library provides atomic operations glib.
• use locks, that's orders of magnitude slower compared fast operation itself.

note: martinho pointed out, while called "atomic", store , load it's not atomic property (operation cannot interrupted , load sees or not see whole store, true of 32-bit stores , loads) ordering property (if store , b, nobody may new value of b , old value of a) hard necessary in case.