diff options
Diffstat (limited to 'erts/doc/src/erl_nif.xml')
| -rw-r--r-- | erts/doc/src/erl_nif.xml | 35 |
1 files changed, 33 insertions, 2 deletions
diff --git a/erts/doc/src/erl_nif.xml b/erts/doc/src/erl_nif.xml index 94aff7c67b..13b72863f3 100644 --- a/erts/doc/src/erl_nif.xml +++ b/erts/doc/src/erl_nif.xml @@ -2526,7 +2526,7 @@ enif_map_iterator_destroy(env, &iter);</code> </func> <func> - <name><ret>int</ret> + <name><ret>enum ErlNifSelectReturn</ret> <nametext>enif_select(ErlNifEnv* env, ErlNifEvent event, enum ErlNifSelectFlags mode, void* obj, Eterm ref)</nametext> </name> @@ -2567,7 +2567,38 @@ enif_map_iterator_destroy(env, &iter);</code> the event object. This safe way of closing event objects must be used even if all notifications have been received and no further calls to <c>enif_select</c> have been made.</p> - <p>Returns 0 on success, or -1 if invalid arguments.</p> + <p>Returns an integer where different bits indicate the outcome of the call:</p> + <taglist> + <tag><c>ERL_NIF_SELECT_ERROR</c></tag> + <item>The master error bit. It will always be set if the call failed for + any reason.</item> + <tag><c>ERL_NIF_SELECT_STOP_CALLED</c></tag> + <item>The stop callback was called directly by <c>enif_select</c>.</item> + <tag><c>ERL_NIF_SELECT_STOP_SCHEDULED</c></tag> + <item>The stop callback was scheduled to run on some other thread + or later by this thread.</item> + <tag><c>ERL_NIF_SELECT_INVALID_EVENT</c></tag> + <item>Argument <c>event</c> is not a valid OS event object.</item> + <tag><c>ERL_NIF_SELECT_FAILED</c></tag> + <item>The system call failed to add the event object to the poll set.</item> + </taglist> + <p>The return value from a successful call with <c>mode</c> as <c>ERL_NIF_SELECT_STOP</c>, + will contain either bit <c>ERL_NIF_SELECT_STOP_CALLED</c> or + <c>ERL_NIF_SELECT_STOP_SCHEDULED</c>.</p> + <note> + <p>Always use bitwise AND to test the return value. New significant bits + may be added in future releases to give more detailed information for both + failed and successful calls. Do NOT use equallity tests like <c>==</c>, as + that may cause your application to stop working.</p> + <p>Example:</p> + <code type="none"> +retval = enif_select(env, fd, ERL_NIF_SELECT_READ, resource, ref); +if (retval & ERL_NIF_SELECT_ERROR) { + /* handle error */ +} +/* Success! */ +</code> + </note> </desc> </func> |