[Buildroot] [PATCH 2/2] support/scripts/graph-build-time: add support for timeline graphing

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

This commit adds support for a new type of graph, showing the timeline
of a build. It shows, with one line per package, when each of this
package steps started/ended, and therefore allows to see the
sequencing of the package builds.

For a fully serialized build like we have today, this is not super
useful (except to show that everything is serialized), but it becomes
much more useful in the context of top-level parallel build.

The graph-build make target is extended to also generate this new
timeline graph.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
---
 Makefile                         |  2 ++
 support/scripts/graph-build-time | 71 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 18afa36b28..49f1106213 100644
--- a/Makefile
+++ b/Makefile
@@ -831,6 +831,8 @@ graph-build: $(O)/build/build-time.log
 				   --type=pie-$(t) --input=$(<) \
 				   --output=$(GRAPHS_DIR)/build.pie-$(t).$(BR_GRAPH_OUT) \
 				   $(if $(BR2_GRAPH_ALT),--alternate-colors)$(sep))
+	./support/scripts/graph-build-time --type=timeline --input=$(<) \
+		--output=$(GRAPHS_DIR)/build.timeline.$(BR_GRAPH_OUT)
 
 .PHONY: graph-depends-requirements
 graph-depends-requirements:
diff --git a/support/scripts/graph-build-time b/support/scripts/graph-build-time
index 892e08bf07..c4aa066050 100755
--- a/support/scripts/graph-build-time
+++ b/support/scripts/graph-build-time
@@ -240,6 +240,73 @@ def pkg_pie_time_per_step(data, output):
     plt.title('Build time per step')
     plt.savefig(output)
 
+step_colors = {
+    'download': 'blue',
+    'extract': 'red',
+    'patch': 'green',
+    'configure': 'black',
+    'build': 'cyan',
+    'install-target': 'orange',
+    'install-staging': 'yellow',
+    'install-images': 'purple',
+    'install-host': 'grey'
+}
+
+def pkg_timeline(data, output):
+    start = 0
+    end = 0
+
+    # Find the first timestamp and the last timestamp
+    for p in data:
+        for k, v in p.steps_start.iteritems():
+            if start == 0 or v < start:
+                start = v
+            if end < v:
+                end = v
+
+    # Readjust all timestamps so that 0 is the start of the build
+    # instead of being Epoch
+    for p in data:
+        for k, v in p.steps_start.iteritems():
+            p.steps_start[k] = v - start
+        for k, v in p.steps_end.iteritems():
+            p.steps_end[k] = v - start
+
+    plt.figure()
+
+    i = 0
+    labels_names = []
+    labels_coords = []
+    # reversing the list, because the packages build first appear last in the list
+    for p in reversed(data):
+        durations = []
+        colors = []
+        for step in steps:
+            if not step in p.steps_start or not step in p.steps_end:
+                continue
+            durations.append((p.steps_start[step],
+                              p.steps_end[step] - p.steps_start[step]))
+            colors.append(step_colors[step])
+        plt.broken_barh(durations, (i, 6), facecolors=colors)
+        labels_coords.append(i + 3)
+        labels_names.append(p.name)
+        i += 10
+
+    axes = plt.gcf().gca()
+
+    axes.set_ylim(0, i + 10)
+    axes.set_xlim(0, end - start)
+    axes.set_xlabel('seconds since start')
+    axes.set_yticks(labels_coords)
+    axes.set_yticklabels(labels_names)
+    axes.set_axisbelow(True)
+    axes.grid(True, linewidth=0.2, zorder=-1)
+
+    plt.gcf().subplots_adjust(left=0.2)
+
+    plt.tick_params(axis='y', which='both', labelsize=6)
+    plt.title('Timeline')
+    plt.savefig(output, dpi=300)
 
 # Parses the csv file passed on standard input and returns a list of
 # Package objects, filed with the duration of each step and the total
@@ -277,7 +344,7 @@ def read_data(input_file):
 
 parser = argparse.ArgumentParser(description='Draw build time graphs')
 parser.add_argument("--type", '-t', metavar="GRAPH_TYPE",
-                    help="Type of graph (histogram, pie-packages, pie-steps)")
+                    help="Type of graph (histogram, pie-packages, pie-steps, timeline)")
 parser.add_argument("--order", '-O', metavar="GRAPH_ORDER",
                     help="Ordering of packages: build or duration (for histogram only)")
 parser.add_argument("--alternate-colors", '-c', action="store_true",
@@ -307,6 +374,8 @@ elif args.type == "pie-packages":
     pkg_pie_time_per_package(d, args.output)
 elif args.type == "pie-steps":
     pkg_pie_time_per_step(d, args.output)
+elif args.type == "timeline":
+    pkg_timeline(d, args.output)
 else:
     sys.stderr.write("Unknown type: %s\n" % args.type)
     exit(1)
-- 
2.14.4