[weston,2/2] compositor: Implement JSON-timeline logging

Submitted by Pekka Paalanen on Nov. 27, 2014, 7:07 a.m.

Details

Message ID 1417072040-15171-2-git-send-email-ppaalanen@gmail.com
State Superseded
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Commit Message

Pekka Paalanen Nov. 27, 2014, 7:07 a.m.
From: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

Logging is activated and deactivated with the debug key binding 't'.
When activated, it creates a new log file, where it records the events.
The log file contains events and detailed object information entries in
JSON format, and is meant to be parsed in sequence from beginning to the
end.

The emitted events are mostly related to the output repaint cycle, like
when repaint begins, is submitted to GPU, and when it completes on a
vblank. This is recorded per-output. Also some per-surface events are
recorded, including when surface damage is flushed.

To reduce the log size, events refer to objects like outputs and
surfaces by id numbers. Detailed object information is emitted only as
needed: on the first object occurrence, and afterwards only if
weston_timeline_object::force_refresh asks for it.

The detailed information for surfaces includes the string returned by
weston_surface::get_description. Therefore it is important to set
weston_timeline_object::force_refresh = 1 whenever the string would
change, so that the new details get recorded.

A rudimentary parser and SVG generator can be found at:
https://github.com/ppaalanen/wesgr

The timeline logs can answer questions including:
- How does the compositor repaint cycle work timing-wise?
- When was the vblank deadline missed?
- What is the latency from surface commit to showing the new content on
  screen?
- How long does it take to process the scenegraph?

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
---
 Makefile.am           |   4 +
 desktop-shell/shell.c |  28 +++--
 src/compositor.c      |  40 +++++++
 src/compositor.h      |   5 +
 src/timeline-object.h |  52 +++++++++
 src/timeline.c        | 287 ++++++++++++++++++++++++++++++++++++++++++++++++++
 src/timeline.h        |  62 +++++++++++
 7 files changed, 469 insertions(+), 9 deletions(-)
 create mode 100644 src/timeline-object.h
 create mode 100644 src/timeline.c
 create mode 100644 src/timeline.h

Patch hide | download patch | download mbox

diff --git a/Makefile.am b/Makefile.am
index e942850..d7b909a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -62,6 +62,9 @@  weston_SOURCES =					\
 	src/noop-renderer.c				\
 	src/pixman-renderer.c				\
 	src/pixman-renderer.h				\
+	src/timeline.c					\
+	src/timeline.h					\
+	src/timeline-object.h				\
 	shared/matrix.c					\
 	shared/matrix.h					\
 	shared/zalloc.h					\
@@ -150,6 +153,7 @@  westonincludedir = $(includedir)/weston
 westoninclude_HEADERS =				\
 	src/version.h				\
 	src/compositor.h			\
+	src/timeline-object.h			\
 	shared/matrix.h				\
 	shared/config-parser.h			\
 	shared/zalloc.h
diff --git a/desktop-shell/shell.c b/desktop-shell/shell.c
index 22e1b25..b3fa3b6 100644
--- a/desktop-shell/shell.c
+++ b/desktop-shell/shell.c
@@ -2246,6 +2246,14 @@  set_title(struct shell_surface *shsurf, const char *title)
 {
 	free(shsurf->title);
 	shsurf->title = strdup(title);
+	shsurf->surface->timeline.force_refresh = 1;
+}
+
+static void
+set_type(struct shell_surface *shsurf, enum shell_surface_type t)
+{
+	shsurf->type = t;
+	shsurf->surface->timeline.force_refresh = 1;
 }
 
 static void
@@ -2276,6 +2284,7 @@  shell_surface_set_class(struct wl_client *client,
 
 	free(shsurf->class);
 	shsurf->class = strdup(class);
+	shsurf->surface->timeline.force_refresh = 1;
 }
 
 static void
@@ -2442,7 +2451,7 @@  set_toplevel(struct shell_surface *shsurf)
 {
 	shell_surface_set_parent(shsurf, NULL);
 	surface_clear_next_states(shsurf);
-	shsurf->type = SHELL_SURFACE_TOPLEVEL;
+	set_type(shsurf, SHELL_SURFACE_TOPLEVEL);
 
 	/* The layer_link is updated in set_surface_type(),
 	 * called from configure. */
@@ -2473,7 +2482,7 @@  set_transient(struct shell_surface *shsurf,
 
 	shsurf->next_state.relative = true;
 	shsurf->state_changed = true;
-	shsurf->type = SHELL_SURFACE_TOPLEVEL;
+	set_type(shsurf, SHELL_SURFACE_TOPLEVEL);
 
 	/* The layer_link is updated in set_surface_type(),
 	 * called from configure. */
@@ -2499,7 +2508,7 @@  set_fullscreen(struct shell_surface *shsurf,
 	       struct weston_output *output)
 {
 	shell_surface_set_output(shsurf, output);
-	shsurf->type = SHELL_SURFACE_TOPLEVEL;
+	set_type(shsurf, SHELL_SURFACE_TOPLEVEL);
 
 	shsurf->fullscreen_output = shsurf->output;
 	shsurf->fullscreen.type = method;
@@ -2584,7 +2593,7 @@  set_popup(struct shell_surface *shsurf,
 	shsurf->popup.x = x;
 	shsurf->popup.y = y;
 
-	shsurf->type = SHELL_SURFACE_POPUP;
+	set_type(shsurf, SHELL_SURFACE_POPUP);
 }
 
 static void
@@ -2688,7 +2697,7 @@  shell_surface_set_maximized(struct wl_client *client,
 	shsurf->next_state.maximized = true;
 	shsurf->state_changed = true;
 
-	shsurf->type = SHELL_SURFACE_TOPLEVEL;
+	set_type(shsurf, SHELL_SURFACE_TOPLEVEL);
 	shell_surface_set_parent(shsurf, NULL);
 
 	if (output_resource)
@@ -2977,7 +2986,7 @@  set_xwayland(struct shell_surface *shsurf, int x, int y, uint32_t flags)
 
 	shell_surface_set_parent(shsurf, NULL);
 
-	shsurf->type = SHELL_SURFACE_XWAYLAND;
+	set_type(shsurf, SHELL_SURFACE_XWAYLAND);
 	shsurf->state_changed = true;
 }
 
@@ -3579,7 +3588,7 @@  create_common_surface(struct shell_client *owner, void *shell,
 	wl_list_init(&shsurf->children_list);
 	shsurf->parent = NULL;
 
-	shsurf->type = SHELL_SURFACE_NONE;
+	set_type(shsurf, SHELL_SURFACE_NONE);
 
 	shsurf->client = client;
 
@@ -3706,6 +3715,7 @@  xdg_surface_set_app_id(struct wl_client *client,
 
 	free(shsurf->class);
 	shsurf->class = strdup(app_id);
+	shsurf->surface->timeline.force_refresh = 1;
 }
 
 static void
@@ -3935,7 +3945,7 @@  create_xdg_surface(struct shell_client *owner, void *shell,
 	if (!shsurf)
 		return NULL;
 
-	shsurf->type = SHELL_SURFACE_TOPLEVEL;
+	set_type(shsurf, SHELL_SURFACE_TOPLEVEL);
 
 	return shsurf;
 }
@@ -4017,7 +4027,7 @@  create_xdg_popup(struct shell_client *owner, void *shell,
 	if (!shsurf)
 		return NULL;
 
-	shsurf->type = SHELL_SURFACE_POPUP;
+	set_type(shsurf, SHELL_SURFACE_POPUP);
 	shsurf->popup.shseat = seat;
 	shsurf->popup.serial = serial;
 	shsurf->popup.x = x;
diff --git a/src/compositor.c b/src/compositor.c
index ea5cc14..cc3b079 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -53,6 +53,8 @@ 
 #include <libunwind.h>
 #endif
 
+#include "timeline.h"
+
 #include "compositor.h"
 #include "scaler-server-protocol.h"
 #include "presentation_timing-server-protocol.h"
@@ -1790,6 +1792,11 @@  surface_flush_damage(struct weston_surface *surface)
 	    wl_shm_buffer_get(surface->buffer_ref.buffer->resource))
 		surface->compositor->renderer->flush_damage(surface);
 
+	if (weston_timeline_enabled_ &&
+	    pixman_region32_not_empty(&surface->damage))
+		TL_POINT("core_flush_damage", TLP_SURFACE(surface),
+			 TLP_OUTPUT(surface->output), TLP_END);
+
 	pixman_region32_clear(&surface->damage);
 }
 
@@ -2014,6 +2021,8 @@  weston_output_repaint(struct weston_output *output)
 	if (output->destroying)
 		return 0;
 
+	TL_POINT("core_repaint_begin", TLP_OUTPUT(output), TLP_END);
+
 	/* Rebuild the surface list and update surface transforms up front. */
 	weston_compositor_build_view_list(ec);
 
@@ -2069,6 +2078,8 @@  weston_output_repaint(struct weston_output *output)
 		animation->frame(animation, output, output->frame_time);
 	}
 
+	TL_POINT("core_repaint_posted", TLP_OUTPUT(output), TLP_END);
+
 	return r;
 }
 
@@ -2092,6 +2103,9 @@  weston_output_finish_frame(struct weston_output *output,
 	int fd, r;
 	uint32_t refresh_nsec;
 
+	TL_POINT("core_repaint_finished", TLP_OUTPUT(output),
+		 TLP_VBLANK(stamp), TLP_END);
+
 	refresh_nsec = 1000000000000UL / output->current_mode->refresh;
 	weston_presentation_feedback_present_list(&output->feedback_list,
 						  output, refresh_nsec, stamp,
@@ -2108,6 +2122,8 @@  weston_output_finish_frame(struct weston_output *output,
 	}
 
 	output->repaint_scheduled = 0;
+	TL_POINT("core_repaint_exit_loop", TLP_OUTPUT(output), TLP_END);
+
 	if (compositor->input_loop_source)
 		return;
 
@@ -2184,6 +2200,9 @@  weston_output_schedule_repaint(struct weston_output *output)
 	    compositor->state == WESTON_COMPOSITOR_OFFSCREEN)
 		return;
 
+	if (!output->repaint_needed)
+		TL_POINT("core_repaint_req", TLP_OUTPUT(output), TLP_END);
+
 	loop = wl_display_get_event_loop(compositor->wl_display);
 	output->repaint_needed = 1;
 	if (output->repaint_scheduled)
@@ -2191,6 +2210,8 @@  weston_output_schedule_repaint(struct weston_output *output)
 
 	wl_event_loop_add_idle(loop, idle_repaint, output);
 	output->repaint_scheduled = 1;
+	TL_POINT("core_repaint_enter_loop", TLP_OUTPUT(output), TLP_END);
+
 
 	if (compositor->input_loop_source) {
 		wl_event_source_remove(compositor->input_loop_source);
@@ -2362,6 +2383,9 @@  weston_surface_commit_state(struct weston_surface *surface,
 	state->buffer_viewport.changed = 0;
 
 	/* wl_surface.damage */
+	if (weston_timeline_enabled_ &&
+	    pixman_region32_not_empty(&state->damage))
+		TL_POINT("core_commit_damage", TLP_SURFACE(surface), TLP_END);
 	pixman_region32_union(&surface->damage, &surface->damage,
 			      &state->damage);
 	pixman_region32_intersect_rect(&surface->damage, &surface->damage,
@@ -2832,6 +2856,7 @@  weston_surface_set_description(struct weston_surface *surface,
 					   char *, size_t))
 {
 	surface->get_description = desc;
+	surface->timeline.force_refresh = 1;
 }
 
 static void
@@ -4037,6 +4062,18 @@  weston_environment_get_fd(const char *env)
 	return fd;
 }
 
+static void
+timeline_key_binding_handler(struct weston_seat *seat, uint32_t time,
+			     uint32_t key, void *data)
+{
+	struct weston_compositor *compositor = data;
+
+	if (weston_timeline_enabled_)
+		weston_timeline_close();
+	else
+		weston_timeline_open(compositor);
+}
+
 WL_EXPORT int
 weston_compositor_init(struct weston_compositor *ec,
 		       struct wl_display *display,
@@ -4134,6 +4171,9 @@  weston_compositor_init(struct weston_compositor *ec,
 	weston_layer_init(&ec->fade_layer, &ec->layer_list);
 	weston_layer_init(&ec->cursor_layer, &ec->fade_layer.link);
 
+	weston_compositor_add_debug_binding(ec, KEY_T,
+					    timeline_key_binding_handler, ec);
+
 	weston_compositor_schedule_repaint(ec);
 
 	return 0;
diff --git a/src/compositor.h b/src/compositor.h
index e49e597..c972f97 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -40,6 +40,7 @@  extern "C" {
 #include "matrix.h"
 #include "config-parser.h"
 #include "zalloc.h"
+#include "timeline-object.h"
 
 #ifndef MIN
 #define MIN(x,y) (((x) < (y)) ? (x) : (y))
@@ -234,6 +235,8 @@  struct weston_output {
 			  uint16_t *r,
 			  uint16_t *g,
 			  uint16_t *b);
+
+	struct weston_timeline_object timeline;
 };
 
 struct weston_pointer_grab;
@@ -916,6 +919,8 @@  struct weston_surface {
 	 * and replace role_name with configure.
 	 */
 	const char *role_name;
+
+	struct weston_timeline_object timeline;
 };
 
 struct weston_subsurface {
diff --git a/src/timeline-object.h b/src/timeline-object.h
new file mode 100644
index 0000000..3716b04
--- /dev/null
+++ b/src/timeline-object.h
@@ -0,0 +1,52 @@ 
+/*
+ * Copyright © 2014 Pekka Paalanen <pq@iki.fi>
+ * Copyright © 2014 Collabora, Ltd.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of the copyright holders not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission.  The copyright holders make
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+ * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef WESTON_TIMELINE_OBJECT_H
+#define WESTON_TIMELINE_OBJECT_H
+
+/*
+ * This struct can be embedded in objects related to timeline output.
+ * It must be initialized to all-zero. Afterwards, the timeline code
+ * will handle it alone. No clean-up is necessary.
+ */
+struct weston_timeline_object {
+	/*
+	 * Timeline series gets bumped every time a new log is opened.
+	 * This triggers id allocation and object info emission.
+	 * 0 is an invalid series value.
+	 */
+	unsigned series;
+
+	/* Object id in the timeline JSON output. 0 is invalid. */
+	unsigned id;
+
+	/*
+	 * If non-zero, forces a re-emission of object description.
+	 * Should be set to non-zero, when changing long-lived
+	 * object state that is not emitted on normal timeline
+	 * events.
+	 */
+	unsigned force_refresh;
+};
+
+#endif /* WESTON_TIMELINE_OBJECT_H */
diff --git a/src/timeline.c b/src/timeline.c
new file mode 100644
index 0000000..5a9f686
--- /dev/null
+++ b/src/timeline.c
@@ -0,0 +1,287 @@ 
+/*
+ * Copyright © 2014 Pekka Paalanen <pq@iki.fi>
+ * Copyright © 2014 Collabora, Ltd.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of the copyright holders not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission.  The copyright holders make
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+ * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "config.h"
+
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <time.h>
+#include <assert.h>
+
+#include "timeline.h"
+#include "compositor.h"
+
+struct timeline_log {
+	clock_t clk_id;
+	FILE *file;
+	unsigned series;
+	struct wl_listener compositor_destroy_listener;
+};
+
+WL_EXPORT int weston_timeline_enabled_;
+static struct timeline_log timeline_ = { CLOCK_MONOTONIC, NULL, 0 };
+
+static int
+weston_timeline_do_open(void)
+{
+	time_t t;
+	struct tm *tmp;
+	char fname[1000];
+	int ret;
+
+	t = time(NULL);
+	tmp = localtime(&t);
+	if (!tmp) {
+		weston_log("Conversion to local time failed, "
+			   "cannot open timeline log file.\n");
+		return -1;
+	}
+
+	ret = strftime(fname, sizeof(fname),
+		       "weston-timeline-%F_%H-%M-%S.log", tmp);
+	if (ret == 0) {
+		weston_log("Time formatting failed, "
+			   "cannot open timeline log file.\n");
+		return -1;
+	}
+
+	timeline_.file = fopen(fname, "w");
+	if (!timeline_.file) {
+		weston_log("Cannot open '%s' for writing: %s\n",
+			   fname, strerror(errno));
+		return -1;
+	}
+
+	weston_log("Opened timeline file '%s'\n", fname);
+
+	return 0;
+}
+
+static void
+timeline_notify_destroy(struct wl_listener *listener, void *data)
+{
+	weston_timeline_close();
+}
+
+void
+weston_timeline_open(struct weston_compositor *compositor)
+{
+	if (weston_timeline_enabled_)
+		return;
+
+	if (weston_timeline_do_open() < 0)
+		return;
+
+	timeline_.compositor_destroy_listener.notify = timeline_notify_destroy;
+	wl_signal_add(&compositor->destroy_signal,
+		      &timeline_.compositor_destroy_listener);
+
+	if (++timeline_.series == 0)
+		++timeline_.series;
+
+	weston_timeline_enabled_ = 1;
+}
+
+void
+weston_timeline_close(void)
+{
+	if (!weston_timeline_enabled_)
+		return;
+
+	weston_timeline_enabled_ = 0;
+
+	wl_list_remove(&timeline_.compositor_destroy_listener.link);
+
+	fclose(timeline_.file);
+	timeline_.file = NULL;
+	weston_log("Timeline log file closed.\n");
+}
+
+struct timeline_emit_context {
+	FILE *cur;
+	FILE *out;
+	unsigned series;
+};
+
+static unsigned
+timeline_new_id(void)
+{
+	static unsigned idc;
+
+	if (++idc == 0)
+		++idc;
+
+	return idc;
+}
+
+static int
+check_series(struct timeline_emit_context *ctx,
+	     struct weston_timeline_object *to)
+{
+	if (to->series == 0 || to->series != ctx->series) {
+		to->series = ctx->series;
+		to->id = timeline_new_id();
+		return 1;
+	}
+
+	if (to->force_refresh) {
+		to->force_refresh = 0;
+		return 1;
+	}
+
+	return 0;
+}
+
+static int
+emit_weston_output(struct timeline_emit_context *ctx, void *obj)
+{
+	struct weston_output *o = obj;
+
+	if (check_series(ctx, &o->timeline))
+		fprintf(ctx->out, "{ \"id\":%u, "
+			"\"type\":\"weston_output\", "
+			"\"name\":%s%s%s }\n",
+			o->timeline.id,
+			o->name ? "\"" : "", o->name ?: "null",
+			o->name ? "\"" : "");
+
+	fprintf(ctx->cur, "\"wo\":%u", o->timeline.id);
+
+	return 1;
+}
+
+static void
+check_weston_surface_description(struct timeline_emit_context *ctx,
+				 struct weston_surface *s)
+{
+	struct weston_surface *mains;
+	const char *q = "\"";
+	char d[512];
+	char mainstr[32];
+
+	if (!check_series(ctx, &s->timeline))
+		return;
+
+	mains = weston_surface_get_main_surface(s);
+	if (mains != s) {
+		check_weston_surface_description(ctx, mains);
+		if (snprintf(mainstr, sizeof(mainstr),
+			     ", \"main_surface\":%u", mains->timeline.id) < 0)
+			mainstr[0] = '\0';
+	} else {
+		mainstr[0] = '\0';
+	}
+
+	if (!s->get_description ||
+	    s->get_description(s, d, sizeof(d)) < 0) {
+		d[0] = '\0';
+		q = "";
+	}
+
+	fprintf(ctx->out, "{ \"id\":%u, "
+		"\"type\":\"weston_surface\", "
+		"\"desc\":%s%s%s%s }\n",
+		s->timeline.id, q, d[0] ? d : "null", q, mainstr);
+}
+
+static int
+emit_weston_surface(struct timeline_emit_context *ctx, void *obj)
+{
+	struct weston_surface *s = obj;
+
+	check_weston_surface_description(ctx, s);
+	fprintf(ctx->cur, "\"ws\":%u", s->timeline.id);
+
+	return 1;
+}
+
+static int
+emit_vblank_timestamp(struct timeline_emit_context *ctx, void *obj)
+{
+	struct timespec *ts = obj;
+
+	fprintf(ctx->cur, "\"vblank\":[%" PRId64 ", %ld]",
+		(int64_t)ts->tv_sec, ts->tv_nsec);
+
+	return 1;
+}
+
+typedef int (*type_func)(struct timeline_emit_context *ctx, void *obj);
+
+static const type_func type_dispatch[] = {
+	[TLT_OUTPUT] = emit_weston_output,
+	[TLT_SURFACE] = emit_weston_surface,
+	[TLT_VBLANK] = emit_vblank_timestamp,
+};
+
+WL_EXPORT void
+weston_timeline_point(const char *name, ...)
+{
+	va_list argp;
+	struct timespec ts;
+	enum timeline_type otype;
+	void *obj;
+	char buf[512];
+	struct timeline_emit_context ctx;
+
+	clock_gettime(timeline_.clk_id, &ts);
+
+	ctx.out = timeline_.file;
+	ctx.cur = fmemopen(buf, sizeof(buf), "w");
+	ctx.series = timeline_.series;
+
+	if (!ctx.cur) {
+		weston_log("Timeline error in fmemopen, closing.\n");
+		weston_timeline_close();
+		return;
+	}
+
+	fprintf(ctx.cur, "{ \"T\":[%" PRId64 ", %ld], \"N\":\"%s\"",
+		(int64_t)ts.tv_sec, ts.tv_nsec, name);
+
+	va_start(argp, name);
+	while (1) {
+		otype = va_arg(argp, enum timeline_type);
+		if (otype == TLT_END)
+			break;
+
+		obj = va_arg(argp, void *);
+		if (type_dispatch[otype]) {
+			fprintf(ctx.cur, ", ");
+			type_dispatch[otype](&ctx, obj);
+		}
+	}
+	va_end(argp);
+
+	fprintf(ctx.cur, " }\n");
+	fflush(ctx.cur);
+	if (ferror(ctx.cur)) {
+		weston_log("Timeline error in constructing entry, closing.\n");
+		weston_timeline_close();
+	} else {
+		fprintf(ctx.out, "%s", buf);
+	}
+
+	fclose(ctx.cur);
+}
diff --git a/src/timeline.h b/src/timeline.h
new file mode 100644
index 0000000..6a6911d
--- /dev/null
+++ b/src/timeline.h
@@ -0,0 +1,62 @@ 
+/*
+ * Copyright © 2014 Pekka Paalanen <pq@iki.fi>
+ * Copyright © 2014 Collabora, Ltd.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of the copyright holders not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission.  The copyright holders make
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+ * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef WESTON_TIMELINE_H
+#define WESTON_TIMELINE_H
+
+extern int weston_timeline_enabled_;
+
+struct weston_compositor;
+
+void
+weston_timeline_open(struct weston_compositor *compositor);
+
+void
+weston_timeline_close(void);
+
+enum timeline_type {
+	TLT_END = 0,
+	TLT_OUTPUT,
+	TLT_SURFACE,
+	TLT_VBLANK,
+};
+
+#define TYPEVERIFY(type, arg) ({			\
+	typeof(arg) tmp___ = (arg);		\
+	(void)((type)0 == tmp___);		\
+	tmp___; })
+
+#define TLP_END TLT_END, NULL
+#define TLP_OUTPUT(o) TLT_OUTPUT, TYPEVERIFY(struct weston_output *, (o))
+#define TLP_SURFACE(s) TLT_SURFACE, TYPEVERIFY(struct weston_surface *, (s))
+#define TLP_VBLANK(t) TLT_VBLANK, TYPEVERIFY(const struct timespec *, (t))
+
+#define TL_POINT(...) do { \
+	if (weston_timeline_enabled_) \
+		weston_timeline_point(__VA_ARGS__); \
+} while (0)
+
+void
+weston_timeline_point(const char *name, ...);
+
+#endif /* WESTON_TIMELINE_H */