u/pacing: Introduce a app pacing factory

src/xrt/auxiliary/util/u_pacing.h

@@ -507,6 +507,69 @@ u_pa_destroy(struct u_pacing_app **upa_ptr)
 	*upa_ptr = NULL;
 }
 
+
+/*
+ *
+ * App pacing factory.
+ *
+ */
+
+/*!
+ * Small helper that creates a app pacers, allows timing information to be
+ * collected and controlled to a central place.
+ */
+struct u_pacing_app_factory
+{
+	/*!
+	 * Create a @ref u_pacing_app.
+	 *
+	 * @param      upaf    App pacing factory.
+	 * @param[out] out_upa Created app pacer.
+	 */
+	xrt_result_t (*create)(struct u_pacing_app_factory *upaf, struct u_pacing_app **out_upa);
+
+	/*!
+	 * Destroy this u_pacing_app_factory.
+	 */
+	void (*destroy)(struct u_pacing_app_factory *upaf);
+};
+
+/*!
+ * @copydoc u_pacing_app_factory::create
+ *
+ * Helper for calling through the function pointer.
+ *
+ * @public @memberof u_pacing_app_factory
+ * @ingroup aux_pacing
+ */
+static inline void
+u_paf_create(struct u_pacing_app_factory *upaf, struct u_pacing_app **out_upa)
+{
+	upaf->create(upaf, out_upa);
+}
+
+/*!
+ * @copydoc u_pacing_app_factory::destroy
+ *
+ * Helper for calling through the function pointer: does a null check and sets
+ * upa_ptr to null if freed.
+ *
+ * @public @memberof u_pacing_app_factory
+ * @ingroup aux_pacing
+ */
+static inline void
+u_paf_destroy(struct u_pacing_app_factory **upaf_ptr)
+{
+	struct u_pacing_app_factory *upaf = *upaf_ptr;
+	if (upaf == NULL) {
+		return;
+	}
+
+	upaf->destroy(upaf);
+	*upaf_ptr = NULL;
+}
+
+
 /*
  *
  * Configuration struct
@@ -585,13 +648,13 @@ xrt_result_t
 u_pc_fake_create(uint64_t estimated_frame_period_ns, uint64_t now_ns, struct u_pacing_compositor **out_upc);
 
 /*!
- * Creates a new application pacing helper.
+ * Creates a new application pacing factory helper.
  *
  * @ingroup aux_pacing
  * @see u_pacing_app
  */
 xrt_result_t
-u_pa_create(struct u_pacing_app **out_upa);
+u_pa_factory_create(struct u_pacing_app_factory **out_upaf);
 
 
 #ifdef __cplusplus

src/xrt/auxiliary/util/u_pacing_app.c

@@ -448,15 +448,8 @@ pa_destroy(struct u_pacing_app *upa)
 	free(upa);
 }
 
-
-/*
- *
- * 'Exported' functions.
- *
- */
-
-xrt_result_t
-u_pa_create(struct u_pacing_app **out_upa)
+static xrt_result_t
+pa_create(struct u_pacing_app **out_upa)
 {
 	struct pacing_app *pa = U_TYPED_CALLOC(struct pacing_app);
 	pa->base.predict = pa_predict;
@@ -479,3 +472,41 @@ u_pa_create(struct u_pacing_app **out_upa)
 
 	return XRT_SUCCESS;
 }
+
+
+/*
+ *
+ * Factory functions.
+ *
+ */
+
+static xrt_result_t
+paf_create(struct u_pacing_app_factory *upaf, struct u_pacing_app **out_upa)
+{
+	return pa_create(out_upa);
+}
+
+static void
+paf_destroy(struct u_pacing_app_factory *upaf)
+{
+	free(upaf);
+}
+
+
+/*
+ *
+ * 'Exported' functions.
+ *
+ */
+
+xrt_result_t
+u_pa_factory_create(struct u_pacing_app_factory **out_upaf)
+{
+	struct u_pacing_app_factory *upaf = U_TYPED_CALLOC(struct u_pacing_app_factory);
+	upaf->create = paf_create;
+	upaf->destroy = paf_destroy;
+
+	*out_upaf = upaf;
+
+	return XRT_SUCCESS;
+}

src/xrt/compositor/main/comp_compositor.c

@@ -51,6 +51,7 @@
 #include "util/u_misc.h"
 #include "util/u_time.h"
 #include "util/u_debug.h"
+#include "util/u_pacing.h"
 #include "util/u_handles.h"
 #include "util/u_trace_marker.h"
 #include "util/u_distortion_mesh.h"
@@ -1268,5 +1269,10 @@ xrt_gfx_provider_create_system(struct xrt_device *xdev, struct xrt_system_compos
 
 	c->state = COMP_STATE_READY;
 
-	return comp_multi_create_system_compositor(&c->base.base, sys_info, out_xsysc);
+	// Standard app pacer.
+	struct u_pacing_app_factory *upaf = NULL;
+	xrt_result_t xret = u_pa_factory_create(&upaf);
+	assert(xret == XRT_SUCCESS && upaf != NULL);
+
+	return comp_multi_create_system_compositor(&c->base.base, upaf, sys_info, out_xsysc);
 }

src/xrt/compositor/multi/comp_multi_compositor.c

@@ -925,7 +925,7 @@ multi_compositor_create(struct multi_system_compositor *msc,
 	os_precise_sleeper_init(&mc->sleeper);
 
 	// This is safe to do without a lock since we are not on the list yet.
-	u_pa_create(&mc->upa);
+	u_paf_create(msc->upaf, &mc->upa);
 
 	os_mutex_lock(&msc->list_and_timing_lock);
 

src/xrt/compositor/multi/comp_multi_interface.h

@@ -16,9 +16,17 @@
 extern "C" {
 #endif
 
+struct u_pacing_app_factory;
 
+
+/*!
+ * Create a system compositor that can handle multiple clients and that drives
+ * a single native compositor. Both the native compositor and the pacing factory
+ * is owned by the multi compositor and destroyed by it.
+ */
 xrt_result_t
 comp_multi_create_system_compositor(struct xrt_compositor_native *xcn,
+                                    struct u_pacing_app_factory *upaf,
                                     const struct xrt_system_compositor_info *xsci,
                                     struct xrt_system_compositor **out_xsysc);
 

src/xrt/compositor/multi/comp_multi_private.h

@@ -240,6 +240,9 @@ struct multi_system_compositor
 	//! Real native compositor.
 	struct xrt_compositor_native *xcn;
 
+	//! App pacer factory.
+	struct u_pacing_app_factory *upaf;
+
 	//! Render loop thread.
 	struct os_thread_helper oth;
 

src/xrt/compositor/multi/comp_multi_system.c

@@ -508,6 +508,8 @@ system_compositor_destroy(struct xrt_system_compositor *xsc)
 	// Destroy the render thread first, destroy also stops the thread.
 	os_thread_helper_destroy(&msc->oth);
 
+	u_paf_destroy(&msc->upaf);
+
 	xrt_comp_native_destroy(&msc->xcn);
 
 	os_mutex_destroy(&msc->list_and_timing_lock);
@@ -524,6 +526,7 @@ system_compositor_destroy(struct xrt_system_compositor *xsc)
 
 xrt_result_t
 comp_multi_create_system_compositor(struct xrt_compositor_native *xcn,
+                                    struct u_pacing_app_factory *upaf,
                                     const struct xrt_system_compositor_info *xsci,
                                     struct xrt_system_compositor **out_xsysc)
 {
@@ -535,6 +538,7 @@ comp_multi_create_system_compositor(struct xrt_compositor_native *xcn,
 	msc->xmcc.set_main_app_visibility = system_compositor_set_main_app_visibility;
 	msc->base.xmcc = &msc->xmcc;
 	msc->base.info = *xsci;
+	msc->upaf = upaf;
 	msc->xcn = xcn;
 
 	os_mutex_init(&msc->list_and_timing_lock);

src/xrt/compositor/null/null_compositor.c

@@ -578,5 +578,10 @@ null_compositor_create_system(struct xrt_device *xdev, struct xrt_system_composi
 
 	NULL_DEBUG(c, "Done %p", (void *)c);
 
-	return comp_multi_create_system_compositor(&c->base.base, &c->sys_info, out_xsysc);
+	// Standard app pacer.
+	struct u_pacing_app_factory *upaf = NULL;
+	xrt_result_t xret = u_pa_factory_create(&upaf);
+	assert(xret == XRT_SUCCESS && upaf != NULL);
+
+	return comp_multi_create_system_compositor(&c->base.base, upaf, &c->sys_info, out_xsysc);
 }