[pulseaudio-discuss] [PATCH 1/5] core: add simple message interface
Georg Chini
georg at chini.tk
Sun Oct 29 19:51:18 UTC 2017
This patch adds a new feature to the core which allows to send messages
to objects. An object can register/unregister a message handler with
pa_message_handler_{register, unregister}() while a message can be sent
to the handler using the pa_message_handler_send_message() function.
A message has 4 arguments (apart from passing the core):
recipient: The name of the message handler that will receive the message
message: message command
message_parameters: A string containing additional parameters
response: Pointer to a response string that will be filled by the
message handler. The caller is responsible to free the string.
The patch is a precondition for the following patches that allow clients
to send messages to pulseaudio objects.
There is no restriction on object names, except that a handler name
always starts with a "/". The intention is to use a path-like syntax,
for example /core/sink_1 for a sink or /name/instances/index for modules.
The exact naming convention still needs to be agreed.
---
src/Makefile.am | 1 +
src/pulsecore/core.c | 4 ++
src/pulsecore/core.h | 2 +-
src/pulsecore/message-handler.c | 104 ++++++++++++++++++++++++++++++++++++++++
src/pulsecore/message-handler.h | 50 +++++++++++++++++++
5 files changed, 160 insertions(+), 1 deletion(-)
create mode 100644 src/pulsecore/message-handler.c
create mode 100644 src/pulsecore/message-handler.h
diff --git a/src/Makefile.am b/src/Makefile.am
index e610db74..24c5ac44 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -957,6 +957,7 @@ libpulsecore_ at PA_MAJORMINOR@_la_SOURCES = \
pulsecore/core-scache.c pulsecore/core-scache.h \
pulsecore/core-subscribe.c pulsecore/core-subscribe.h \
pulsecore/core.c pulsecore/core.h \
+ pulsecore/message-handler.c pulsecore/message-handler.h \
pulsecore/hook-list.c pulsecore/hook-list.h \
pulsecore/ltdl-helper.c pulsecore/ltdl-helper.h \
pulsecore/modargs.c pulsecore/modargs.h \
diff --git a/src/pulsecore/core.c b/src/pulsecore/core.c
index 454c5668..bcab9ed1 100644
--- a/src/pulsecore/core.c
+++ b/src/pulsecore/core.c
@@ -103,6 +103,7 @@ pa_core* pa_core_new(pa_mainloop_api *m, bool shared, bool enable_memfd, size_t
c->namereg = pa_hashmap_new(pa_idxset_string_hash_func, pa_idxset_string_compare_func);
c->shared = pa_hashmap_new(pa_idxset_string_hash_func, pa_idxset_string_compare_func);
+ c->message_handlers = pa_hashmap_new(pa_idxset_string_hash_func, pa_idxset_string_compare_func);
c->default_source = NULL;
c->default_sink = NULL;
@@ -204,6 +205,9 @@ static void core_free(pa_object *o) {
pa_assert(pa_hashmap_isempty(c->shared));
pa_hashmap_free(c->shared);
+ pa_assert(pa_hashmap_isempty(c->message_handlers));
+ pa_hashmap_free(c->message_handlers);
+
pa_assert(pa_hashmap_isempty(c->modules_pending_unload));
pa_hashmap_free(c->modules_pending_unload);
diff --git a/src/pulsecore/core.h b/src/pulsecore/core.h
index 79a095d2..bc8a371e 100644
--- a/src/pulsecore/core.h
+++ b/src/pulsecore/core.h
@@ -160,7 +160,7 @@ struct pa_core {
pa_idxset *clients, *cards, *sinks, *sources, *sink_inputs, *source_outputs, *modules, *scache;
/* Some hashmaps for all sorts of entities */
- pa_hashmap *namereg, *shared;
+ pa_hashmap *namereg, *shared, *message_handlers;
/* The default sink/source as configured by the user. If the user hasn't
* explicitly configured anything, these are set to NULL. These are strings
diff --git a/src/pulsecore/message-handler.c b/src/pulsecore/message-handler.c
new file mode 100644
index 00000000..06e3680e
--- /dev/null
+++ b/src/pulsecore/message-handler.c
@@ -0,0 +1,104 @@
+/***
+ This file is part of PulseAudio.
+
+ PulseAudio is free software; you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as published
+ by the Free Software Foundation; either version 2.1 of the License,
+ or (at your option) any later version.
+
+ PulseAudio is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#include <pulse/xmalloc.h>
+
+#include <pulsecore/core.h>
+#include <pulsecore/core-util.h>
+#include <pulsecore/log.h>
+#include <pulsecore/macro.h>
+
+#include "message-handler.h"
+
+/* Message handler functions */
+
+/* Register message handler. recipient_name must be a unique name starting with "/". */
+void pa_message_handler_register(pa_core *c, const char *recipient_name, const char *description, pa_message_handler_cb_t cb, void *userdata) {
+ struct pa_message_handler *handler;
+
+ pa_assert(c);
+ pa_assert(recipient_name);
+ pa_assert(cb);
+ pa_assert(userdata);
+
+ /* Ensure that the recipient name is not empty and starts with "/". */
+ pa_assert(recipient_name[0] == '/');
+
+ handler = pa_xnew0(struct pa_message_handler, 1);
+ handler->userdata = userdata;
+ handler->callback = cb;
+ handler->recipient = pa_xstrdup(recipient_name);
+ handler->description = pa_xstrdup(description);
+
+ pa_assert_se(pa_hashmap_put(c->message_handlers, handler->recipient, (void *) handler) == 0);
+}
+
+/* Unregister a message handler */
+void pa_message_handler_unregister(pa_core *c, const char *recipient_name) {
+ struct pa_message_handler *handler;
+
+ pa_assert(c);
+ pa_assert(recipient_name);
+
+ pa_assert_se(handler = pa_hashmap_remove(c->message_handlers, recipient_name));
+
+ pa_xfree(handler->recipient);
+ pa_xfree(handler->description);
+ pa_xfree(handler);
+}
+
+/* Send a message to a recipient or recipient group */
+int pa_message_handler_send_message(pa_core *c, const char *recipient_name, const char *message, const char *message_parameters, char **response) {
+ struct pa_message_handler *handler;
+
+ pa_assert(c);
+ pa_assert(recipient_name);
+ pa_assert(message);
+ pa_assert(response);
+
+ *response = NULL;
+
+ if (!(handler = pa_hashmap_get(c->message_handlers, recipient_name)))
+ return -PA_ERR_NOENTITY;
+
+ /* The handler is expected to return an error code and may also
+ return an error string in response */
+ return handler->callback(handler->recipient, message, message_parameters, response, handler->userdata);
+}
+
+/* Set handler description */
+int pa_message_handler_set_description(pa_core *c, const char *recipient_name, const char *description) {
+ struct pa_message_handler *handler;
+
+ pa_assert(c);
+ pa_assert(recipient_name);
+
+ if (!(handler = pa_hashmap_get(c->message_handlers, recipient_name)))
+ return -PA_ERR_NOENTITY;
+
+ pa_xfree(handler->description);
+ handler->description = pa_xstrdup(description);
+
+ return PA_OK;
+}
diff --git a/src/pulsecore/message-handler.h b/src/pulsecore/message-handler.h
new file mode 100644
index 00000000..8cb34c3a
--- /dev/null
+++ b/src/pulsecore/message-handler.h
@@ -0,0 +1,50 @@
+#ifndef foocoremessageshfoo
+#define foocoremessageshfoo
+
+/***
+ This file is part of PulseAudio.
+
+ PulseAudio is free software; you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as published
+ by the Free Software Foundation; either version 2.1 of the License,
+ or (at your option) any later version.
+
+ PulseAudio is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <pulsecore/core.h>
+
+/* Message handler types and functions */
+
+/* Prototype for message callback */
+typedef int (*pa_message_handler_cb_t)(
+ const char *recipient,
+ const char *message,
+ const char *message_parameters,
+ char **response,
+ void *userdata);
+
+/* Message handler object */
+struct pa_message_handler {
+ char *recipient;
+ char *description;
+ pa_message_handler_cb_t callback;
+ void *userdata;
+};
+
+/* Handler registration */
+void pa_message_handler_register(pa_core *c, const char *recipient_name, const char *description, pa_message_handler_cb_t cb, void *userdata);
+void pa_message_handler_unregister(pa_core *c, const char *recipient_name);
+
+/* Send message to recipient */
+int pa_message_handler_send_message(pa_core *c, const char *recipient_name, const char *message, const char *message_parameters, char **response);
+
+/* Set handler description */
+int pa_message_handler_set_description(pa_core *c, const char *recipient_name, const char *description);
+#endif
--
2.14.1
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