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diff --git a/lib/ose/doc/src/ose_signals_chapter.xml b/lib/ose/doc/src/ose_signals_chapter.xml deleted file mode 100644 index bcf2259577..0000000000 --- a/lib/ose/doc/src/ose_signals_chapter.xml +++ /dev/null @@ -1,240 +0,0 @@ -<?xml version="1.0" encoding="utf-8" ?> -<!DOCTYPE chapter SYSTEM "chapter.dtd"> - -<chapter> - <header> - <copyright> - <year>2013</year><year>2014</year> - <holder>Ericsson AB. All Rights Reserved.</holder> - </copyright> - <legalnotice> - Licensed under the Apache License, Version 2.0 (the "License"); - you may not use this file except in compliance with the License. - You may obtain a copy of the License at - - http://www.apache.org/licenses/LICENSE-2.0 - - Unless required by applicable law or agreed to in writing, software - distributed under the License is distributed on an "AS IS" BASIS, - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. - See the License for the specific language governing permissions and - limitations under the License. - - </legalnotice> - - <title>Interacting with Enea OSE</title> - <prepared>Lukas Larsson</prepared> - <docno></docno> - <date>2014-01-08</date> - <rev>A</rev> - <file>ose_signals_chapter.xml</file> - </header> - - <marker id="introduction"></marker> - <section> - <title>Introduction</title> - <p>The main way which programs on Enea OSE interact is through the - usage of message passing, much the same way as Erlang processes - communicate. There are two ways in which an Erlang programmer can - interact with the signals sent from other Enea OSE processes; either - through the provided <c>ose</c> module, or by writing a custom linked-in - driver. This User's Guide describes and provides examples for both - approaches. - </p> - </section> - - <marker id="erlang"></marker> - <section> - <title>Signals in Erlang</title> - <p>Erlang/OTP on OSE provides a erlang module called - <seealso marker="ose:ose">ose</seealso> that can be used to interact - with other OSE processes using message passing. The api in the module - is very similar to the native OSE api, so for details of how the - functions work please refer to the official OSE documenation. Below - is an example usage of the API. - </p> - <code>1> P1 = ose:open("p1"). -#Port>0.344> -2> ose:hunt(P1,"p2"). -{#Port>0.344>,1} -3> P2 = ose:open("p2"). -#Port>0.355> -4> flush(). -Shell got {mailbox_up,#Port>0.344>,{#Port>0.344>,1},852189} -ok -5> ose:listen(P1,[1234]). -ok -6> ose:send(P2,ose:get_id(P1),1234,>>"hello">>). -ok -7> flush(). -Shell got {message,#Port>0.344>,{852189,1245316,1234,>>"hello">>}} -ok</code> - </section> - - <marker id="driver"></marker> - <section> - <title>Signals in a Linked-in driver</title> - <p> - Writing Linked-in drivers for OSE is very similar to how it is done - for Unix/Windows. It is only the way in which the driver subscribes - and consumed external events that is different. In Unix (and Windows) - file descriptiors (and Event Objects) are used to select on. On OSE - we use signals to deliver the same functionality. There are two large - differences between a signal and an fd. - </p> - <p> - In OSE it is not possible for a signal number to be a unique identifier - for a resource in the same way as an fd is. For example; let's say we - implement a driver that does an asynchronous hunt that uses signal - number 1234 as the hunt_sig. If we want to be able to have multiple - hunt ports running at the same time we have to have someway of routing - the signal to the correct port. This is achieved by supplying a secondary - id that can be retrieved through the meta-data or payload of the signal, - e.g: - <code>ErlDrvEvent event = erl_drv_ose_event_alloc(1234,port,resolver);</code> - The event you get back from - <seealso marker="ose_erl_driver#erl_drv_ose_event_alloc"> - erl_drv_ose_event_alloc</seealso> can then be used by - <seealso marker="erts:erl_driver#driver_select">driver_select</seealso> - to subscribe to signals. The first argument is just the signal number - that we are interested in. The second is the id that we choose to use, - in this case the port id that we got in the - <seealso marker="erts:driver_entry#start">start</seealso> callback is - used. The third argument is a function pointer to a function that can - be used to figure out the id from a given signal. The fourth argument can - point to any additional data you might want to associate with the event. - There is a complete. You can examine the data contained in the event with - <seealso marker="ose_erl_driver#erl_drv_ose_event_fetch">erl_drv_ose_event_fetch</seealso> - , eg: - <code>erl_drv_ose_event_fetch(event, &signal, &port, (void **)&extra);</code> - example of what this could look like in - <seealso marker="#example">the next section</seealso>. - <note>It is very important to issue the driver_select call before - any of the signals you are interested in are sent. If driver_select - is called after the signal is sent, there is a high probability that it - will be lost.</note> - </p> - <p> - The other difference from unix is that in OSE the payload of the event - (i.e. the signal data) is already received when the ready_output/input - callbacks are called. This means that you access the data of a signal - by calling <seealso marker="ose_erl_driver#erl_drv_ose_get_signal"> - erl_drv_ose_get_signal</seealso>. Additionally multiple signals might be - associated with the event, so you should call - <seealso marker="ose_erl_driver#erl_drv_ose_get_signal"> - erl_drv_ose_get_signal</seealso> until <c>NULL</c> is returned. - </p> - </section> - - <marker id="example"></marker> - <section> - <title>Example Linked-in driver</title> -<code>#include "erl_driver.h" -#include "ose.h" - -struct huntsig { - SIGSELECT signo; - ErlDrvPort port; -}; - -union SIGNAL { - SIGSELECT signo; - struct huntsig; -} - -/* Here we have to get the id from the signal. In this case we use the - port id since we have control over the data structure of the signal. - It is however possible to use anything in here. The only restriction - is that the same id has to be used for all signals of the same number.*/ -ErlDrvOseEventId resolver(union SIGNAL *sig) { - return (ErlDrvOseEventId)sig->huntsig.port; -} - -static int drv_init(void) { return 0; }; - -static ErlDrvData drv_start(ErlDrvPort port, char *command) { - return (ErlDrvData)port; -} - -static ErlDrvSSizeT control(ErlDrvData driver_data, unsigned int cmd, - char *buf, ErlDrvSizeT len, - char **rbuf, ErlDrvSizeT rlen) { - ErlDrvPort port = (ErlDrvPort)driver_data; - - /* An example of extra data to associate with the event */ - char *extra_data = driver_alloc(80); - snprintf("extra_data, "Event, sig_no: 1234, and port: %d", port); - - /* Create a new event to select on */ - ErlDrvOseEvent evt = erl_drv_ose_event_alloc(1234,port,resolver, extra_data); - - /* Make sure to do the select call _BEFORE_ the signal arrives. - The signal might get lost if the hunt call is done before the - select. */ - driver_select(port,evt,ERL_DRV_READ|ERL_DRV_USE,1); - - union SIGNAL *sig = alloc(sizeof(union SIGNAL),1234); - sig->huntsig.port = port; - hunt("testprocess",0,NULL,&sig); - return 0; -} - -static void ready_input(ErlDrvData driver_data, ErlDrvEvent evt) { - char *extra_data; - /* Get the first signal payload from the event */ - union SIGNAL *sig = erl_drv_ose_get_signal(evt); - ErlDrvPort port = (ErlDrvPort)driver_data; - while (sig != NULL) { - if (sig->signo == 1234) { - /* Print out the string we added as the extra parameter */ - erl_drv_ose_event_fetch(evt, NULL, NULL, (void **)&extra_data); - printf("We've received: %s\n", extra_data); - - /* If it is our signal we send a message with the sender of the signal - to the controlling erlang process */ - ErlDrvTermData reply[] = { ERL_DRV_UINT, (ErlDrvUInt)sender(&sig) }; - erl_drv_send_term(port,reply,sizeof(reply) / sizeof(reply[0])); - } - - /* Cleanup the signal and deselect on the event. - Note that the event itself has to be free'd in the stop_select - callback. */ - free_buf(&sig); - driver_select(port,evt,ERL_DRV_READ|ERL_DRV_USE,0); - - /* There could be more than one signal waiting in this event, so - we have to loop until sig == NULL */ - sig = erl_drv_ose_get_signal(evt); - } -} - -static void stop_select(ErlDrvEvent event, void *reserved) -{ - /* Free the extra_data */ - erl_drv_ose_event_fetch(evt, NULL, NULL, (void **)&extra_data); - driver_free(extra_data); - - /* Free the event itself */ - erl_drv_ose_event_free(event); -} - -/** - * Setup the driver entry for the Erlang runtime - **/ -ErlDrvEntry ose_signal_driver_entry = { - .init = drv_init, - .start = drv_start, - .stop = drv_stop, - .ready_input = ready_input, - .driver_name = DRIVER_NAME, - .control = control, - .extended_marker = ERL_DRV_EXTENDED_MARKER, - .major_version = ERL_DRV_EXTENDED_MAJOR_VERSION, - .minor_version = ERL_DRV_EXTENDED_MINOR_VERSION, - .driver_flags = ERL_DRV_FLAG_USE_PORT_LOCKING, - .stop_select = stop_select -}; -</code> - </section> - -</chapter> |