A thread must not block outside of a libguile function while it is in guile mode. The following functions can be used to temporily leave guile mode or to perform some common blocking operations in a supported way.
Leave guile mode, call func on data, enter guile mode and return the result of calling func.
While a thread has left guile mode, it must not call any libguile functions except
scm_without_guileand must not use any libguile macros. Also, local variables of type
SCMthat are allocated while not in guile mode are not protected from the garbage collector.
When used from non-guile mode, calling
scm_without_guileis still allowed: it simply calls func. In that way, you can leave guile mode without having to know whether the current thread is in guile mode or not.
pthread_mutex_lock, but leaves guile mode while waiting for the mutex.
pthread_cond_timedwait, but leaves guile mode while waiting for the condition variable.
selectbut leaves guile mode while waiting. Also, the delivery of a system async causes this function to be interrupted with error code
sleep, but leaves guile mode while sleeping. Also, the delivery of a system async causes this function to be interrupted.