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authorSverker Eriksson <[email protected]>2017-05-09 21:26:09 +0200
committerSverker Eriksson <[email protected]>2017-05-10 11:28:46 +0200
commit8222631bd1aa0e0fb8fea52bc984865d4433d182 (patch)
treebe832a745f2368ec8b813ccd36a2a745071fee1d /erts/doc/src
parentc002dc9493a2ae9b01d49e39b9e89ef38b165973 (diff)
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erts: Improve erl_nif docs
Diffstat (limited to 'erts/doc/src')
-rw-r--r--erts/doc/src/erl_nif.xml32
1 files changed, 25 insertions, 7 deletions
diff --git a/erts/doc/src/erl_nif.xml b/erts/doc/src/erl_nif.xml
index 51ba70994a..3eb3e04f33 100644
--- a/erts/doc/src/erl_nif.xml
+++ b/erts/doc/src/erl_nif.xml
@@ -714,6 +714,7 @@ typedef struct {
typedef struct {
ErlNifResourceDtor* dtor;
ErlNifResourceStop* stop;
+ ErlNifResourceDown* down;
} ErlNifResourceTypeInit;</code>
<p>Initialization structure read by <seealso marker="#enif_open_resource_type_x">
enif_open_resource_type_x</seealso>.</p>
@@ -1395,13 +1396,12 @@ typedef enum {
<p>Returns <c>true</c> if a pending exception is associated with the
environment <c>env</c>. If <c>reason</c> is a <c>NULL</c> pointer,
ignore it. Otherwise, if a pending exception associated with
- <c>env</c> exists, set <c>ERL_NIF_TERM</c> to which <c>reason</c>
- points to the value of the exception's term. For example, if
- <seealso marker="#enif_make_badarg">
+ <c>env</c> exists, set <c>*reason</c> to the value of the exception
+ term. For example, if <seealso marker="#enif_make_badarg">
<c>enif_make_badarg</c></seealso> is called to set a pending
<c>badarg</c> exception, a later call to
<c>enif_has_pending_exception(env, &amp;reason)</c> sets
- <c>reason</c> to the atom <c>badarg</c>, then return <c>true</c>.</p>
+ <c>*reason</c> to the atom <c>badarg</c>, then return <c>true</c>.</p>
<p>See also <seealso marker="#enif_make_badarg">
<c>enif_make_badarg</c></seealso> and
<seealso marker="#enif_raise_exception">
@@ -2384,20 +2384,23 @@ enif_map_iterator_destroy(env, &amp;iter);</code>
called in the two callbacks
<seealso marker="#load"><c>load</c></seealso> and
<seealso marker="#upgrade"><c>upgrade</c></seealso>.</p>
+ <p>See also <seealso marker="#enif_open_resource_type_x">
+ <c>enif_open_resource_type_x</c></seealso>.</p>
</desc>
</func>
<func>
<name><ret>ErlNifResourceType *</ret>
<nametext>enif_open_resource_type_x(ErlNifEnv* env, const char* name,
- ErlNifResourceTypeInit* init,
+ const ErlNifResourceTypeInit* init,
ErlNifResourceFlags flags, ErlNifResourceFlags* tried)</nametext>
</name>
<fsummary>Create or takeover a resource type.</fsummary>
<desc>
<p>Same as <seealso marker="#enif_open_resource_type"><c>enif_open_resource_type</c></seealso>
- except is also accept a <c>stop</c> callback for resource types that are
- used together with <seealso marker="#enif_select"><c>enif_select</c></seealso>.</p>
+ except it accepts additional callback functions for resource types that are
+ used together with <seealso marker="#enif_select"><c>enif_select</c></seealso>
+ and <seealso marker="#enif_monitor_process"><c>enif_monitor_process</c></seealso>.</p>
<p>Argument <c>init</c> is a pointer to an
<seealso marker="#ErlNifResourceTypeInit"><c>ErlNifResourceTypeInit</c></seealso>
structure that contains the function pointers for destructor, down and stop callbacks
@@ -2695,6 +2698,21 @@ enif_map_iterator_destroy(env, &amp;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>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
+ <c>obj</c>. The relation is dissolved when <c>enif_select</c> has
+ been called with <c>mode</c> as <c>ERL_NIF_SELECT_STOP</c> and the
+ corresponding <c>stop</c> callback has returned. A resource can contain
+ several event objects but one event object can only be contained within
+ one resource. A resource will not be destructed until all its contained relations
+ have been dissolved.</p>
+ <note>
+ <p>Use <seealso marker="#enif_monitor_process"><c>enif_monitor_process</c></seealso>
+ together with <c>enif_select</c> to detect failing Erlang
+ processes and prevent them from causing permanent leakage of resources
+ and their contained OS event objects.</p>
+ </note>
<p>Returns a non-negative value on success where the following bits can be set:</p>
<taglist>
<tag><c>ERL_NIF_SELECT_STOP_CALLED</c></tag>