<html><head><style type="text/css">.style1 {font-family: "Times New Roman";}</style></head><body>Hi Sverker,<BR>
<BR>
> On 21 Apr 2021, at 17:37, Sverker Eriksson <sverker.eriksson@ericsson.com> wrote:<BR>
><BR>
> At process termination the deallocation of the heap is delayed until a running dirty NIF has returned. This to make sure the dirty NIF can safely continue read its arguments.<BR>
<BR>
That makes things somewhat simpler; thank you.<BR>
<BR>
> The firing of links and monitors (including NIF monitor down calls), on the other hand, are not delayed by a running dirty NIF.<BR>
<BR>
Is enif_monitor_process() serialised with respect to the delivery of<BR>
an exit signal by a concurrent thread? I.e. if the function returns zero<BR>
and the caller is later killed then is it guaranteed that its down<BR>
callback will be invoked? I am wondering if (absent any documentation<BR>
to the contrary) there might exist a race condition in which process A<BR>
might kill process B at exactly the time that the latter calls<BR>
enif_monitor_process(), e.g. in the (untested) code below.<BR>
<BR>
Regards,<BR>
<BR>
Robert<BR>
<BR>
<BR>
<BR>
/* resource object */<BR>
typedef struct foo {<BR>
int abort;<BR>
...<BR>
} foo_t;<BR>
<BR>
void<BR>
down(ErlNifEnv *env, void *obj, ErlNifPid *pid, ErlNifMonitor *mon)<BR>
{<BR>
((foo_t *)obj)->abort = 1;<BR>
}<BR>
<BR>
ERL_NIF_TERM<BR>
some_dirty_nif(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])<BR>
{<BR>
foo_t *foop;<BR>
ErlNifPid pid;<BR>
ErlNifMonitor monitor;<BR>
<BR>
enif_get_resource(env, argv[0], foo_resource, (void **)&foop));<BR>
foop->abort = 0;<BR>
<BR>
enif_self(env, &pid);<BR>
if (enif_monitor_process(env, foop, pid, &monitor) > 0)<BR>
/* process already dead; abort */<BR>
<BR>
/* lost a signal here? */<BR>
<BR>
while (/* some very long loop */) {<BR>
if (foop->abort) {<BR>
/* process waiting to die; abort */<BR>
...<BR>
}<BR>
/* do stuff */<BR>
}<BR>
<BR>
/* no longer care about being directed to abort */<BR>
enif_demonitor_process(env, foop, &monitor);<BR>
/* return */<BR>
...<BR>
}<BR>
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