diff options
Diffstat (limited to 'erts/doc')
| -rw-r--r-- | erts/doc/src/erl_nif.xml | 182 |
1 files changed, 181 insertions, 1 deletions
diff --git a/erts/doc/src/erl_nif.xml b/erts/doc/src/erl_nif.xml index 74a551d60b..a55092332e 100644 --- a/erts/doc/src/erl_nif.xml +++ b/erts/doc/src/erl_nif.xml @@ -696,11 +696,46 @@ typedef struct { Each resource type has a unique name and a destructor function that is called when objects of its type are released.</p> </item> + <tag><marker id="ErlNifResourceTypeInit"/><c>ErlNifResourceTypeInit</c></tag> + <item> + <code type="none"> +typedef struct { + ErlNifResourceDtor* dtor; + ErlNifResourceStop* stop; +} ErlNifResourceTypeInit;</code> + <p>Initialization structure read by <seealso marker="#enif_open_resource_type_x"> + enif_open_resource_type_x</seealso>.</p> + </item> <tag><marker id="ErlNifResourceDtor"/><c>ErlNifResourceDtor</c></tag> <item> <code type="none"> typedef void ErlNifResourceDtor(ErlNifEnv* env, void* obj);</code> <p>The function prototype of a resource destructor function.</p> + <p>The <c>obj</c> argument is a pointer to the resource. The only + allowed use for the resource in the destructor is to access its + user data one final time. The destructor is guaranteed to be the + last callback before the resource is deallocated.</p> + </item> + <tag><marker id="ErlNifResourceDown"/><c>ErlNifResourceDown</c></tag> + <item> + <code type="none"> +typedef void ErlNifResourceDown(ErlNifEnv* env, void* obj, const ErlNifPid* pid, const ErlNifMonitor* mon);</code> + <p>The function prototype of a resource down function, + called on the behalf of <seealso marker="#enif_monitor_process"> + enif_monitor_process</seealso>. <c>obj</c> is the resource, <c>pid</c> + is the identity of the monitored process that is exiting, and <c>mon</c> + is the identity of the monitor. + </p> + </item> + <tag><marker id="ErlNifResourceStop"/><c>ErlNifResourceStop</c></tag> + <item> + <code type="none"> +typedef void ErlNifResourceStop(ErlNifEnv* env, void* obj, ErlNifEvent event, int is_direct_call);</code> + <p>The function prototype of a resource stop function, + called on the behalf of <seealso marker="#enif_select"> + enif_select</seealso>. <c>obj</c> is the resource, <c>event</c> is OS event, + <c>is_direct_call</c> is true if the call is made directly from <c>enif_select</c> + or false if it is a scheduled call (potentially from another thread).</p> </item> <tag><marker id="ErlNifCharEncoding"/><c>ErlNifCharEncoding</c></tag> <item> @@ -1002,6 +1037,29 @@ typedef enum { </func> <func> + <name><ret>int</ret><nametext>enif_demonitor_process(ErlNifEnv* env, void* obj, + const ErlNifMonitor* mon)</nametext></name> + <fsummary>Cancel a process monitor.</fsummary> + <desc> + <marker id="enif_demonitor_process"></marker> + <p>Cancels a monitor created earlier with <seealso marker="enif_monitor_process"> + <c>enif_monitor_process</c></seealso>. Argument <c>obj</c> is a pointer + to the resource holding the monitor and <c>*mon</c> identifies the monitor.</p> + <p>Returns <c>0</c> if the monitor was successfully identified and removed. + Returns a non-zero value if the monitor could not be identified, which means + it was either</p> + <list type="bulleted"> + <item>never created for this resource</item> + <item>already triggered</item> + <item>just about to be triggered by a concurrent thread</item> + </list> + <p>This function is only thread-safe when the emulator with SMP support + is used. It can only be used in a non-SMP emulator from a NIF-calling + thread.</p> + </desc> + </func> + + <func> <name><ret>int</ret> <nametext>enif_equal_tids(ErlNifTid tid1, ErlNifTid tid2)</nametext> </name> @@ -2117,6 +2175,31 @@ enif_map_iterator_destroy(env, &iter);</code> </func> <func> + <name><ret>int</ret><nametext>enif_monitor_process(ErlNifEnv* env, void* obj, + const ErlNifPid* target_pid, ErlNifMonitor* mon)</nametext></name> + <fsummary>Monitor a process from a resource.</fsummary> + <desc> + <marker id="enif_monitor_process"></marker> + <p>Starts monitoring a process from a resource. When a process is + monitored, a process exit results in a call to the provided + <seealso marker="ErlNifResourceDown"> + <c>down</c></seealso> callback associated with the resource type.</p> + <p>Argument <c>obj</c> is pointer to the resource to hold the monitor and + <c>*target_pid</c> identifies the local process to be monitored.</p> + <p>If <c>mon</c> is not <c>NULL</c>, a successful call stores the + identity of the monitor in the struct pointed to by <c>mon</c>. + This identifier is used to refer to the monitor for later removal or + compare. A monitor is automatically removed when it triggers or when + the resource is deallocated.</p> + <p>Returns <c>0</c> on success, < 0 if no <c>down</c> callback is + provided, and > 0 if the process is no longer alive.</p> + <p>This function is only thread-safe when the emulator with SMP support + is used. It can only be used in a non-SMP emulator from a NIF-calling + thread.</p> + </desc> + </func> + + <func> <name><ret>ErlNifTime</ret> <nametext>enif_monotonic_time(ErlNifTimeUnit time_unit)</nametext> </name> @@ -2236,6 +2319,24 @@ enif_map_iterator_destroy(env, &iter);</code> </func> <func> + <name><ret>ErlNifResourceType *</ret> + <nametext>enif_open_resource_type_x(ErlNifEnv* env, const char* name, + 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> + <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 + for the resource type.</p> + </desc> + </func> + + <func> <name><ret>int</ret><nametext>enif_port_command(ErlNifEnv* env, const ErlNifPort* to_port, ErlNifEnv *msg_env, ERL_NIF_TERM msg)</nametext> </name> @@ -2342,7 +2443,7 @@ enif_map_iterator_destroy(env, &iter);</code> <nametext>enif_release_resource(void* obj)</nametext></name> <fsummary>Release a resource object.</fsummary> <desc> - <p>Removes a reference to resource object <c>obj</c>obtained from + <p>Removes a reference to resource object <c>obj</c> obtained from <seealso marker="#enif_alloc_resource"> <c>enif_alloc_resource</c></seealso>. The resource object is destructed when the last reference is removed. @@ -2482,6 +2583,85 @@ enif_map_iterator_destroy(env, &iter);</code> </func> <func> + <name><ret>int</ret> + <nametext>enif_select(ErlNifEnv* env, ErlNifEvent event, enum ErlNifSelectFlags mode, + void* obj, const ErlNifPid* pid, ERL_NIF_TERM ref)</nametext> + </name> + <fsummary>Manage subscription on IO event.</fsummary> + <desc> + <p>This function can be used to receive asynchronous notifications + when OS-specific event objects become ready for either read or write operations.</p> + <p>Argument <c>event</c> identifies the event object. On Unix + systems, the functions <c>select</c>/<c>poll</c> are used. The event + object must be a socket, pipe or other file descriptor object that + <c>select</c>/<c>poll</c> can use.</p> + <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 triggerred, + a notification message like this is sent to the process identified by + <c>pid</c>:</p> + <code type="none"><c>{select, Obj, Ref, ready_input | ready_output}</c></code> + <p><c>ready_input</c> or <c>ready_output</c> indicates if the event object + is ready for reading or writing.</p> + <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>. + The purpose of the resource objects is as a container of the event object + to manage its state and lifetime. A handle to the resource is received + in the notification message as <c>Obj</c>.</p> + <p>Argument <c>ref</c> must be either a reference obtained from + <seealso marker="erlang#make_ref-0"><c>erlang:make_ref/0</c></seealso> + 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> + <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>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> + <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> + <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> + </taglist> + <p>Returns a negative value if the call failed where the follwing bits can be set:</p> + <taglist> + <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> + <note> + <p>Use bitwise AND to test for specific bits in the return vaue. + 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_STOP, resource, ref); +if (retval < 0) { + /* handle error */ +} +/* Success! */ +if (retval & ERL_NIF_SELECT_STOP_CALLED) { + /* ... */ +} +</code> + </note> + </desc> + </func> + + <func> <name><ret>ErlNifPid *</ret> <nametext>enif_self(ErlNifEnv* caller_env, ErlNifPid* pid)</nametext> </name> |