Ensure that there is only one GUsbSource for each GUsbContext

As a result, g_usb_source_{new,destroy} have been moved to a private
header, and are called from the get_source and finalize methods of
GUsbContext.

Note that the GUsbSource is lazy allocated and only created when
g_usb_context_get_source is called for the first time for a particular
GUsbContext.

9 files changed, 93 insertions, 29 deletions

diff --git a/gusb/Makefile.am b/gusb/Makefile.am
index e2690b0..2d4999a 100644
--- a/gusb/Makefile.am
+++ b/gusb/Makefile.am
@@ -26,6 +26,7 @@ libgusbbase_include_HEADERS =					\
 	gusb-device-private.h					\
 	gusb-device-list.h					\
 	gusb-source.h						\
+	gusb-source-private.h					\
 	gusb-util.h
 
 libgusb_la_SOURCES =						\
diff --git a/gusb/gusb-context.c b/gusb/gusb-context.c
index 2abd5b4..cccd8ff 100644
--- a/gusb/gusb-context.c
+++ b/gusb/gusb-context.c
@@ -33,6 +33,7 @@
 #include "gusb-util.h"
 #include "gusb-context.h"
 #include "gusb-context-private.h"
+#include "gusb-source-private.h"
 
 static void g_usb_context_finalize (GObject *object);
 
@@ -51,6 +52,8 @@ enum {
  **/
 struct _GUsbContextPrivate
 {
+	GStaticMutex		 source_mutex;
+	GUsbSource		*source;
 	libusb_context		*context;
 	int			 debug_level;
 };
@@ -179,7 +182,11 @@ g_usb_context_class_init (GUsbContextClass *klass)
 static void
 g_usb_context_init (GUsbContext *context)
 {
-	context->priv = G_USB_CONTEXT_GET_PRIVATE (context);
+	GUsbContextPrivate *priv;
+
+	priv = context->priv = G_USB_CONTEXT_GET_PRIVATE (context);
+	g_static_mutex_init (&priv->source_mutex);
+	priv->source = NULL;
 }
 
 /**
@@ -191,6 +198,10 @@ g_usb_context_finalize (GObject *object)
 	GUsbContext *context = G_USB_CONTEXT (object);
 	GUsbContextPrivate *priv = context->priv;
 
+	g_static_mutex_free (&priv->source_mutex);
+	if (priv->source != NULL)
+		_g_usb_source_destroy (priv->source);
+
 	libusb_exit (priv->context);
 
 	G_OBJECT_CLASS (g_usb_context_parent_class)->finalize (object);
@@ -229,6 +240,34 @@ _g_usb_context_get_context (GUsbContext *context)
 }
 
 /**
+ * g_usb_context_get_source:
+ * @context: a #GUsbContext
+ * @main_ctx: a #GMainContext, or %NULL
+ *
+ * Returns a source for this context. The first call actually creates
+ * the source and the result is returned in all future calls.
+ *
+ * Return value: (transfer none): the #GUsbSource.
+ *
+ * Since: 0.1.0
+ **/
+GUsbSource *
+g_usb_context_get_source (GUsbContext *context,
+			  GMainContext *main_ctx)
+{
+	GUsbContextPrivate *priv = context->priv;
+
+	if (priv->source == NULL) {
+		g_static_mutex_lock (&priv->source_mutex);
+		if (priv->source == NULL)
+			priv->source = _g_usb_source_new (main_ctx, context);
+		g_static_mutex_unlock (&priv->source_mutex);
+	}
+
+	return priv->source;
+}
+
+/**
  * g_usb_context_set_debug:
  * @context: a #GUsbContext
  * @flags: a GLogLevelFlags such as %G_LOG_LEVEL_ERROR | %G_LOG_LEVEL_INFO, or 0
diff --git a/gusb/gusb-context.h b/gusb/gusb-context.h
index 6387bfb..5a6ad46 100644
--- a/gusb/gusb-context.h
+++ b/gusb/gusb-context.h
@@ -23,6 +23,7 @@
 #define __GUSB_CONTEXT_H__
 
 #include <glib-object.h>
+#include <gusb/gusb-source.h>
 #include <gusb/gusb-util.h>
 
 G_BEGIN_DECLS
@@ -62,6 +63,9 @@ GQuark		 g_usb_context_error_quark	(void);
 
 GUsbContext	*g_usb_context_new		(GError		**error);
 
+GUsbSource	*g_usb_context_get_source	(GUsbContext	*context,
+						 GMainContext	*main_ctx);
+
 void		 g_usb_context_set_debug	(GUsbContext	*context,
 						 GLogLevelFlags	 flags);
 
diff --git a/gusb/gusb-device.c b/gusb/gusb-device.c
index 6d73661..4071018 100644
--- a/gusb/gusb-device.c
+++ b/gusb/gusb-device.c
@@ -34,7 +34,6 @@
 #include <libusb-1.0/libusb.h>
 
 #include "gusb-context.h"
-#include "gusb-source.h"
 #include "gusb-util.h"
 #include "gusb-device.h"
 #include "gusb-device-private.h"
@@ -601,7 +600,6 @@ g_usb_device_interrupt_transfer	(GUsbDevice	*device,
 typedef struct {
 	GCancellable		*cancellable;
 	gulong			 cancellable_id;
-	GUsbSource		*source;
 	struct libusb_transfer	*transfer;
 	GSimpleAsyncResult	*res;
 	guint8			*data; /* owned by the user */
@@ -616,7 +614,6 @@ g_usb_device_req_free (GcmDeviceReq *req)
 		g_object_unref (req->cancellable);
 	}
 
-	g_usb_source_destroy (req->source);
 	libusb_free_transfer (req->transfer);
 	g_object_unref (req->res);
 	g_slice_free (GcmDeviceReq, req);
@@ -857,8 +854,7 @@ g_usb_device_control_transfer_async	(GUsbDevice	*device,
 	}
 
 	/* setup with the default mainloop */
-	req->source = g_usb_source_new (NULL,
-					device->priv->context);
+	g_usb_context_get_source (device->priv->context, NULL);
 }
 
 /**********************************************************************/
@@ -971,8 +967,7 @@ g_usb_device_bulk_transfer_async (GUsbDevice *device,
 	}
 
 	/* setup with the default mainloop */
-	req->source = g_usb_source_new (NULL,
-					device->priv->context);
+	g_usb_context_get_source (device->priv->context, NULL);
 }
 
 /**********************************************************************/
@@ -1085,8 +1080,7 @@ g_usb_device_interrupt_transfer_async (GUsbDevice *device,
 	}
 
 	/* setup with the default mainloop */
-	req->source = g_usb_source_new (NULL,
-					device->priv->context);
+	g_usb_context_get_source (device->priv->context, NULL);
 }
 
 /**********************************************************************/
diff --git a/gusb/gusb-private.h b/gusb/gusb-private.h
index dc3607e..fa67cd1 100644
--- a/gusb/gusb-private.h
+++ b/gusb/gusb-private.h
@@ -27,6 +27,7 @@
 #include <gusb/gusb.h>
 #include <gusb/gusb-context-private.h>
 #include <gusb/gusb-device-private.h>
+#include <gusb/gusb-source-private.h>
 
 #undef __GUSB_INSIDE__
 
diff --git a/gusb/gusb-self-test.c b/gusb/gusb-self-test.c
index 26d0e95..df37039 100644
--- a/gusb/gusb-self-test.c
+++ b/gusb/gusb-self-test.c
@@ -24,7 +24,6 @@
 #include <glib-object.h>
 
 #include "gusb-context.h"
-#include "gusb-source.h"
 #include "gusb-device.h"
 #include "gusb-device-list.h"
 
@@ -54,12 +53,11 @@ gusb_source_func (void)
 	g_assert_no_error (error);
 	g_assert (ctx != NULL);
 
-	source = g_usb_source_new (NULL, ctx);
-	g_assert (ctx != NULL);
+	source = g_usb_context_get_source (ctx, NULL);
+	g_assert (source != NULL);
 
 	/* TODO: test callback? */
 
-	g_usb_source_destroy (source);
 	g_object_unref (ctx);
 }
 
diff --git a/gusb/gusb-source-private.h b/gusb/gusb-source-private.h
new file mode 100644
index 0000000..a7509de
--- /dev/null
+++ b/gusb/gusb-source-private.h
@@ -0,0 +1,35 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*-
+ *
+ * Copyright (C) 2011 Debarshi Ray <debarshir@src.gnome.org>
+ *
+ * Licensed under the GNU Lesser General Public License Version 2.1
+ *
+ * This library 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.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GUSB_SOURCE_PRIVATE_H__
+#define __GUSB_SOURCE_PRIVATE_H__
+
+#include <gusb/gusb-context.h>
+#include <gusb/gusb-source.h>
+
+G_BEGIN_DECLS
+
+GUsbSource	*_g_usb_source_new		(GMainContext	*main_ctx,
+						 GUsbContext	*context);
+void		 _g_usb_source_destroy		(GUsbSource	*source);
+
+G_END_DECLS
+
+#endif /* __GUSB_SOURCE_PRIVATE_H__ */
diff --git a/gusb/gusb-source.c b/gusb/gusb-source.c
index ddb4635..c9c931f 100644
--- a/gusb/gusb-source.c
+++ b/gusb/gusb-source.c
@@ -37,6 +37,7 @@
 #include "gusb-context-private.h"
 #include "gusb-util.h"
 #include "gusb-source.h"
+#include "gusb-source-private.h"
 
 /**
  * g_usb_source_error_quark:
@@ -57,7 +58,6 @@ g_usb_source_error_quark (void)
 struct _GUsbSource {
 	GSource		 source;
 	GSList		*pollfds;
-	GUsbContext	*usbcontext;
 	libusb_context	*ctx;
 };
 
@@ -208,7 +208,6 @@ static void
 g_usb_source_finalize (GSource *source)
 {
 	GUsbSource *usb_source = (GUsbSource *)source;
-	g_object_unref (usb_source->usbcontext);
 	g_slist_free (usb_source->pollfds);
 }
 
@@ -221,20 +220,20 @@ static GSourceFuncs usb_source_funcs = {
 };
 
 /**
- * g_usb_source_new:
+ * _g_usb_source_new:
  * @main_ctx: a #GMainContext, or %NULL
  * @gusb_ctx: a #GUsbContext
  * @error: a #GError, or %NULL
  *
  * Creates a source for integration into libusb1.
  *
- * Return value: (transfer none): the #GUsbSource. Use g_usb_source_destroy() to unref.
+ * Return value: (transfer none): the #GUsbSource. Use _g_usb_source_destroy() to unref.
  *
  * Since: 0.1.0
  **/
 GUsbSource *
-g_usb_source_new (GMainContext *main_ctx,
-		  GUsbContext *gusb_ctx)
+_g_usb_source_new (GMainContext *main_ctx,
+		   GUsbContext *gusb_ctx)
 {
 	guint i;
 	const struct libusb_pollfd **pollfds;
@@ -243,7 +242,6 @@ g_usb_source_new (GMainContext *main_ctx,
 	gusb_source = (GUsbSource *)g_source_new (&usb_source_funcs,
 						  sizeof(GUsbSource));
 	gusb_source->pollfds = NULL;
-	gusb_source->usbcontext = g_object_ref (gusb_ctx);
 	gusb_source->ctx = _g_usb_context_get_context (gusb_ctx);
 
 	/* watch the fd's already created */
@@ -265,7 +263,7 @@ g_usb_source_new (GMainContext *main_ctx,
 }
 
 /**
- * g_usb_source_destroy:
+ * _g_usb_source_destroy:
  * @source: a #GUsbSource
  *
  * Destroys a #GUsbSource
@@ -273,7 +271,7 @@ g_usb_source_new (GMainContext *main_ctx,
  * Since: 0.1.0
  **/
 void
-g_usb_source_destroy (GUsbSource *source)
+_g_usb_source_destroy (GUsbSource *source)
 {
 	libusb_set_pollfd_notifiers (source->ctx, NULL, NULL, NULL);
 	g_usb_source_pollfd_remove_all (source);
diff --git a/gusb/gusb-source.h b/gusb/gusb-source.h
index b840c67..909659e 100644
--- a/gusb/gusb-source.h
+++ b/gusb/gusb-source.h
@@ -25,8 +25,6 @@
 
 #include <glib.h>
 
-#include <gusb/gusb-context.h>
-
 G_BEGIN_DECLS
 
 #define G_USB_SOURCE_ERROR			(g_usb_source_error_quark ())
@@ -43,10 +41,6 @@ typedef enum {
 } GUsbSourceError;
 
 GQuark		 g_usb_source_error_quark	(void);
-GUsbSource	*g_usb_source_new		(GMainContext	*main_ctx,
-						 GUsbContext	*gusb_ctx);
-void		 g_usb_source_destroy		(GUsbSource	*source);
-
 void		 g_usb_source_set_callback	(GUsbSource	*source,
 						 GSourceFunc	 func,
 						 gpointer	 data,