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#ifndef IPC_SYNC_H_
#define IPC_SYNC_H_
/**
* Normal usage:
* 1) ipc_sync_init()
* 2) fork a new process
* 3) process x: ipc_sync_wait()
* process y: ipc_sync_signal()
* 4) both processes: ipc_sync_done()
*
* If there's a need to make _wait() or _signal() as fast as possible
* (e.g. for a benchmark or a performance bottleneck), call the
* relevant _prep() function before the critical section.
*/
/* Opaque structure. */
struct ipc_sync;
/**
* ipc_sync_init(void):
* Initialize an inter-process synchronization barrier. This must be called
* before forking.
*/
struct ipc_sync * ipc_sync_init(void);
/**
* ipc_sync_wait(IS):
* Block until ipc_sync_signal() has been called with ${IS}.
*/
int ipc_sync_wait(struct ipc_sync *);
/**
* ipc_sync_signal(IS):
* Indicate that ${IS} should no longer block.
*/
int ipc_sync_signal(struct ipc_sync *);
/**
* ipc_sync_wait_prep(IS):
* Perform any operation(s) that would speed up an upcoming call to
* ipc_sync_wait(). Calling this function is optional.
*/
int ipc_sync_wait_prep(struct ipc_sync *);
/**
* ipc_sync_signal_prep(IS):
* Perform any operation(s) that would speed up an upcoming call to
* ipc_sync_signal(). Calling this function is optional.
*/
int ipc_sync_signal_prep(struct ipc_sync *);
/**
* ipc_sync_done(IS):
* Free resources associated with ${IS}.
*/
int ipc_sync_done(struct ipc_sync *);
#endif /* !IPC_SYNC_H_ */
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