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-rw-r--r--erts/doc/src/erl_nif.xml90
1 files changed, 83 insertions, 7 deletions
diff --git a/erts/doc/src/erl_nif.xml b/erts/doc/src/erl_nif.xml
index 5cbeddabd9..d58ebd3171 100644
--- a/erts/doc/src/erl_nif.xml
+++ b/erts/doc/src/erl_nif.xml
@@ -2217,6 +2217,18 @@ enif_inspect_iovec(env, max_elements, term, &tail, &iovec);
</func>
<func>
+ <name since="OTP @OTP-15362@"><ret>ERL_NIF_TERM</ret>
+ <nametext>enif_make_monitor_term(ErlNifEnv* env, const ErlNifMonitor* mon)</nametext></name>
+ <fsummary>Make monitor term from the given monitor identifier.</fsummary>
+ <desc>
+ <p>Creates a term identifying the given monitor received from
+ <seealso marker="#enif_monitor_process"><c>enif_monitor_process</c>
+ </seealso>.</p>
+ <p>This function is primarily intended for debugging purpose.</p>
+ </desc>
+ </func>
+
+ <func>
<name since="OTP R14B"><ret>unsigned char *</ret><nametext>enif_make_new_binary(ErlNifEnv*
env, size_t size, ERL_NIF_TERM* termp)</nametext></name>
<fsummary>Allocate and create a new binary term.</fsummary>
@@ -3056,12 +3068,18 @@ enif_map_iterator_destroy(env, &amp;iter);</code>
<p>Argument <c>mode</c> describes the type of events to wait for. It can be
<c>ERL_NIF_SELECT_READ</c>, <c>ERL_NIF_SELECT_WRITE</c> or a bitwise
OR combination to wait for both. It can also be <c>ERL_NIF_SELECT_STOP</c>
- which is described further below. When a read or write event is triggered,
+ or <c>ERL_NIF_SELECT_CANCEL</c> which are described further
+ below. When a read or write event is triggered,
a notification message like this is sent to the process identified by
<c>pid</c>:</p>
<code type="none">{select, Obj, Ref, ready_input | ready_output}</code>
<p><c>ready_input</c> or <c>ready_output</c> indicates if the event object
is ready for reading or writing.</p>
+ <note><p>For complete control over the message format use the newer functions
+ <seealso marker="#enif_select_read"><c>enif_select_read</c></seealso> or
+ <seealso marker="#enif_select_write"><c>enif_select_write</c></seealso>
+ introduced in erts-11.0 (OTP-22.0).</p>
+ </note>
<p>Argument <c>pid</c> may be <c>NULL</c> to indicate the calling process.</p>
<p>Argument <c>obj</c> is a resource object obtained from
<seealso marker="#enif_alloc_resource"><c>enif_alloc_resource</c></seealso>.
@@ -3073,17 +3091,29 @@ enif_map_iterator_destroy(env, &amp;iter);</code>
or the atom <c>undefined</c>. It will be passed as <c>Ref</c> in the notifications.
If a selective <c>receive</c> statement is used to wait for the notification
then a reference created just before the <c>receive</c> will exploit a runtime
- optimization that bypasses all earlier received messages in the queue.</p>
+ optimization that bypasses all earlier received messages in the
+ queue.</p>
<p>The notifications are one-shot only. To receive further notifications of the same
type (read or write), repeated calls to <c>enif_select</c> must be made
after receiving each notification.</p>
+ <p><c>ERL_NIF_SELECT_CANCEL</c> can be used to cancel previously
+ selected events. It must be used in a bitwise OR combination with
+ <c>ERL_NIF_SELECT_READ</c> and/or <c>ERL_NIF_SELECT_WRITE</c> to
+ indicate which type of event to cancel. Arguments <c>pid</c> and
+ <c>ref</c> are ignored when <c>ERL_NIF_SELECT_CANCEL</c> is specified.
+ The return value will tell if the event was actualy cancelled or if a
+ notification may already have been sent.</p>
<p>Use <c>ERL_NIF_SELECT_STOP</c> as <c>mode</c> in order to safely
close an event object that has been passed to <c>enif_select</c>. The
<seealso marker="#ErlNifResourceStop"><c>stop</c></seealso> callback
of the resource <c>obj</c> will be called when it is safe to close
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>
+ even if all notifications have been received (or cancelled) and no
+ further calls to <c>enif_select</c> have been made.
+ <c>ERL_NIF_SELECT_STOP</c> will first cancel any selected events
+ before it calls or schedules the <c>stop</c> callback. Arguments
+ <c>pid</c> and <c>ref</c> are ignored when <c>ERL_NIF_SELECT_STOP</c>
+ is specified.</p>
<p>The first call to <c>enif_select</c> for a specific OS <c>event</c> will establish
a relation between the event object and the containing resource. All subsequent calls
for an <c>event</c> must pass its containing resource as argument
@@ -3105,7 +3135,15 @@ enif_map_iterator_destroy(env, &amp;iter);</code>
<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>
+ or later by this thread.</item>
+ <tag><c>ERL_NIF_SELECT_READ_CANCELLED</c></tag>
+ <item>A read event was cancelled by <c>ERL_NIF_SELECT_CANCEL</c> or
+ <c>ERL_NIF_SELECT_STOP</c> and is guaranteed not to generate a
+ <c>ready_input</c> notification message.</item>
+ <tag><c>ERL_NIF_SELECT_WRITE_CANCELLED</c></tag>
+ <item>A write event was cancelled by <c>ERL_NIF_SELECT_CANCEL</c> or
+ <c>ERL_NIF_SELECT_STOP</c> and is guaranteed not to generate a
+ <c>ready_output</c> notification message.</item>
</taglist>
<p>Returns a negative value if the call failed where the following bits can be set:</p>
<taglist>
@@ -3131,6 +3169,43 @@ if (retval &amp; ERL_NIF_SELECT_STOP_CALLED) {
}
</code>
</note>
+ <note><p>The mode flag <c>ERL_NIF_SELECT_CANCEL</c> and the return flags
+ <c>ERL_NIF_SELECT_READ_CANCELLED</c> and
+ <c>ERL_NIF_SELECT_WRITE_CANCELLED</c> were introduced in erts-11.0
+ (OTP-22.0).</p>
+ </note>
+ </desc>
+ </func>
+
+ <func>
+ <name since="OTP 22.0"><ret>int</ret>
+ <nametext>enif_select_read(ErlNifEnv* env, ErlNifEvent event, void* obj,
+ const ErlNifPid* pid, ERL_NIF_TERM msg, ErlNifEnv* msg_env)</nametext>
+ </name>
+ <name since="OTP 22.0"><ret>int</ret>
+ <nametext>enif_select_write(ErlNifEnv* env, ErlNifEvent event, void* obj,
+ const ErlNifPid* pid, ERL_NIF_TERM msg, ErlNifEnv* msg_env)</nametext>
+ </name>
+ <fsummary>Manage subscription on IO event.</fsummary>
+ <desc>
+ <p>These are variants of <seealso marker="#enif_select">enif_select</seealso>
+ where you can supply your own message term <c>msg</c> that will be sent to
+ the process instead of the predefined tuple <c>{select,_,_,_}.</c></p>
+ <p>Argument <c>msg_env</c> must either be <c>NULL</c> or the environment of
+ <c>msg</c> allocated with <seealso marker="#enif_alloc_env">
+ <c>enif_alloc_env</c></seealso>. If argument <c>msg_env</c> is
+ <c>NULL</c> the term <c>msg</c> will be copied, otherwise both
+ <c>msg</c> and <c>msg_env</c> will be invalidated by a successful call
+ to <c>enif_select_read</c> or <c>enif_select_write</c>. The environment
+ is then to either be freed with <seealso marker="#enif_free_env">
+ <c>enif_free_env</c></seealso> or cleared for reuse with
+ <seealso marker="#enif_clear_env"><c>enif_clear_env</c></seealso>. An
+ unsuccessful call will leave <c>msg</c> and <c>msg_env</c> still valid.</p>
+ <p>Apart from the message format <c>enif_select_read</c> and
+ <c>enif_select_write</c> behaves exactly the same as <seealso
+ marker="#enif_select">enif_select</seealso> with argument <c>mode</c> as
+ either <c>ERL_NIF_SELECT_READ</c> or <c>ERL_NIF_SELECT_WRITE</c>. To
+ cancel or close events use <seealso marker="#enif_select">enif_select</seealso>.</p>
</desc>
</func>
@@ -3179,8 +3254,9 @@ if (retval &amp; ERL_NIF_SELECT_STOP_CALLED) {
<c>msg</c>) is invalidated by a successful call to <c>enif_send</c>.
The environment is to either be freed with
<seealso marker="#enif_free_env">
- <c>enif_free_env</c></seealso> of cleared for reuse with
- <seealso marker="#enif_clear_env"><c>enif_clear_env</c></seealso>.</p>
+ <c>enif_free_env</c></seealso> or cleared for reuse with
+ <seealso marker="#enif_clear_env"><c>enif_clear_env</c></seealso>. An
+ unsuccessful call will leave <c>msg</c> and <c>msg_env</c> still valid.</p>
<p>If <c>msg_env</c> is set to <c>NULL</c>, the <c>msg</c> term is
copied and the original term and its environment is still valid after
the call.</p>