Merge lp:~mhr3/libunity/easy-tracing into lp:libunity

[Michal Hruby]

Make tracing easy.

Make tracing easy using new capture_trace.py script in tools/.

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PASSED: Continuous integration, rev:302
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PASSED: Continuous integration, rev:303
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    SUCCESS: http://10.97.0.26:8080/job/libunity-saucy-armhf-ci/111
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PASSED: Continuous integration, rev:304
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    SUCCESS: http://10.97.0.26:8080/job/libunity-saucy-armhf-ci/112
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FAILED: Continuous integration, rev:306
http://jenkins.qa.ubuntu.com/job/libunity-ci/131/
Executed test runs:
    FAILURE: http://jenkins.qa.ubuntu.com/job/libunity-trusty-amd64-ci/2/console
    FAILURE: http://jenkins.qa.ubuntu.com/job/libunity-trusty-armhf-ci/2/console
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review: Needs Fixing (continuous-integration)

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PASSED: Continuous integration, rev:308
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PASSED: Continuous integration, rev:309
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review: Approve (continuous-integration)

[Paweł Stołowski (stolowski)]

Nice stuff, +1!

review: Approve

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PASSED: Continuous integration, rev:310
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FAILED: Autolanding.
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review: Needs Fixing (continuous-integration)

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PASSED: Continuous integration, rev:311
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review: Approve (continuous-integration)

[Michal Hruby (mhr3)]

Looks like unrelated race in Dee that caused a failure here.

=== modified file 'debian/libunity9.symbols'
--- debian/libunity9.symbols	2013-10-24 15:19:00 +0000
+++ debian/libunity9.symbols	2013-10-25 14:15:10 +0000
@@ -689,6 +689,7 @@
  unity_string_array_wrapper_take_strings@Base 4.0.6
  unity_trace_log_object_real@Base 5.0.0
  unity_trace_log_object_va@Base 5.0.0
+ unity_trace_tracepoint_va@Base 0replaceme
  unity_track_metadata_construct@Base 4.0.0
  unity_track_metadata_construct_full@Base 5.92.0
  unity_track_metadata_get_album@Base 4.0.0
 
=== modified file 'src/unity-aggregator-scope-private.vala'
--- src/unity-aggregator-scope-private.vala	2013-10-24 11:27:10 +0000
+++ src/unity-aggregator-scope-private.vala	2013-10-25 14:15:10 +0000
@@ -1194,13 +1194,13 @@
     if (measure_requests) search_start_time = get_monotonic_time ();
     int64 search_end_time = search_start_time;
 
-    Unity.Trace.tracepoint ("%s run start: %s", Log.METHOD, owner.id);
-
     var glib_cancellable = search_cancellable.get_gcancellable ();
     ulong canc_sig_id = 0;
     uint canc_src_id = 0;
     bool was_cancelled = false;
 
+    Unity.Trace.tracepoint ("search:start::scope=%s;query=%s", owner.id, search_string);
+
     // danger ahead, we're running the search in (possibly) different thread
     // and at the same time waiting for the cancellable while holding
     // channel lock (ChannelState set to SEARCH_ACTIVE), other searches won't
@@ -1246,6 +1246,8 @@
       yield;
     }
 
+    Unity.Trace.tracepoint ("search:end::scope=%s;query=%s", owner.id, search_string);
+
     if (search_cancellable.is_cancelled ())
     {
       throw new ScopeError.SEARCH_CANCELLED ("Search '%s' was cancelled", search_string);
@@ -1262,8 +1264,6 @@
         response.insert (key, variant);
     }
 
-    Unity.Trace.tracepoint ("%s run end: %s", Log.METHOD, owner.id);
-
     result_set.flush ();
     response[SEARCH_SEQNUM_HINT] = new Variant.uint64 (channel.get_last_seqnum ());
     if (measure_requests)
@@ -1351,10 +1351,21 @@
     if (category_merger is CategoryMergerByScope)
       (category_merger as CategoryMergerByScope).add_scope_mapping (owner, master_scope_id);
 
-    var channel = get_channel_by_id (channel_id);
-    yield _scopes.push_wrapper (channel, search_string, ChannelType.GLOBAL,
-                                master_scope_id, scope_id,
-                                results_model, category_ids, cancellable);
+    Unity.Trace.tracepoint ("push:start::scope=%s;target=%s;query=%s",
+                            master_scope_id, scope_id, search_string);
+
+    try
+    {
+      var channel = get_channel_by_id (channel_id);
+      yield _scopes.push_wrapper (channel, search_string, ChannelType.GLOBAL,
+                                  master_scope_id, scope_id,
+                                  results_model, category_ids, cancellable);
+    }
+    finally
+    {
+      Unity.Trace.tracepoint ("push:end::scope=%s;target=%s;query=%s",
+                              master_scope_id, scope_id, search_string);
+    }
   }
 
   public void push_filter_settings (string channel_id, FilterSet filters)
@@ -1456,7 +1467,7 @@
     }
 
     _channels[channel.id] = channel;
-    _scopes.register_channel (channel.id, channel.backend_model, merge_strategy);
+    _scopes.register_channel (owner.id, channel.id, channel.backend_model, merge_strategy);
 
     out_hints = new HashTable<string, Variant> (str_hash, str_equal);
     out_hints[CHANNEL_SWARM_NAME_HINT] = new Variant.string (model_name);
 
=== modified file 'src/unity-deprecated-scope-impl.vala'
--- src/unity-deprecated-scope-impl.vala	2013-09-24 08:57:39 +0000
+++ src/unity-deprecated-scope-impl.vala	2013-10-25 14:15:10 +0000
@@ -491,7 +491,7 @@
       if (measure_requests) search_start_time = get_monotonic_time ();
       int64 search_end_time = search_start_time;
 
-      Unity.Trace.tracepoint ("%s run start: %s", Log.METHOD, owner.id);
+      Unity.Trace.tracepoint ("search:start::scope=%s", owner.id);
 
       new_search.run_async (() =>
       {
@@ -506,7 +506,8 @@
         result[SEARCH_SEQNUM_HINT] = new Variant.uint64 (channel.get_last_seqnum ());
       }
 
-      Unity.Trace.tracepoint ("%s run end: %s", Log.METHOD, owner.id);
+      Unity.Trace.tracepoint ("search:end::scope=%s", owner.id);
+
       if (measure_requests)
       {
         int64 delta_us = search_end_time - search_start_time;
 
=== modified file 'src/unity-models.vala'
--- src/unity-models.vala	2013-07-17 15:18:49 +0000
+++ src/unity-models.vala	2013-10-25 14:15:10 +0000
@@ -119,6 +119,7 @@
     var sm = flush_model as Dee.SharedModel;
     if (sm != null)
     {
+      Unity.Trace.tracepoint ("flush::%s", sm.get_swarm_name ());
       sm.flush_revision_queue ();
     }
   }
@@ -195,6 +196,7 @@
       return;
     }
 
+    Unity.Trace.tracepoint ("diff:start::%s", get_swarm_name ());
     var script = Utils.Diff.run ((int) this_rows, (int) target_rows,
                                  (index_a, index_b) =>
     {
@@ -249,6 +251,7 @@
         }
       }
     }
+    Unity.Trace.tracepoint ("diff:end::%s", get_swarm_name ());
 
     assert (get_n_rows () == target_model.get_n_rows ());
   }
 
=== modified file 'src/unity-scope-dbus-impl.vala'
--- src/unity-scope-dbus-impl.vala	2013-09-24 08:57:39 +0000
+++ src/unity-scope-dbus-impl.vala	2013-10-25 14:15:10 +0000
@@ -566,7 +566,7 @@
       if (measure_requests) search_start_time = get_monotonic_time ();
       int64 search_end_time = search_start_time;
 
-      Unity.Trace.tracepoint ("%s run start: %s", Log.METHOD, _dbus_name);
+      Unity.Trace.tracepoint ("search:start::scope=%s;query=%s", _dbus_name, normalized_query);
 
       if (force_sync_requests)
       {
@@ -590,7 +590,7 @@
         yield;
       }
 
-      Unity.Trace.tracepoint ("%s run end: %s", Log.METHOD, _dbus_name);
+      Unity.Trace.tracepoint ("search:end::scope=%s;query=%s", _dbus_name, normalized_query);
 
       // FIXME: handle no-reply-hint etc!
       if (!cancellable.is_cancelled ())
 
=== modified file 'src/unity-scope-tracker.vala'
--- src/unity-scope-tracker.vala	2013-09-24 08:57:39 +0000
+++ src/unity-scope-tracker.vala	2013-10-25 14:15:10 +0000
@@ -224,12 +224,13 @@
     return "%p::%d".printf (proxy, (int) channel_type);
   }
 
-  public void register_channel (string master_channel_id,
+  public void register_channel (string owner_scope_id,
+                                string master_channel_id,
                                 Dee.SerializableModel model,
                                 MergeStrategy merge_strategy)
   {
     // create new synchronizer for this channel
-    var synchronizer = new ResultsSynchronizer (model);
+    var synchronizer = new ResultsSynchronizer (model, owner_scope_id);
     synchronizer.merge_strategy = merge_strategy;
     synchronizers[master_channel_id] = synchronizer;
   }
 
=== modified file 'src/unity-search.vala'
--- src/unity-search.vala	2013-07-22 14:02:05 +0000
+++ src/unity-search.vala	2013-10-25 14:15:10 +0000
@@ -176,10 +176,10 @@
     }
     var agg_scope = owner as AggregatorScope;
     var canc = search_context.cancellable.get_gcancellable ();
-    Unity.Trace.tracepoint ("%s start: %s, query=%s", Log.METHOD, scope_id, search_string);
+    Unity.Trace.tracepoint ("subsearch:start::scope=%s;target=%s;query=%s", agg_scope.id, scope_id, search_string);
     var res = yield agg_scope.search_scope (this, scope_id, search_string,
                                             search_type, hints, canc);
-    Unity.Trace.tracepoint ("%s end: %s, query=%s", Log.METHOD, scope_id, search_string);
+    Unity.Trace.tracepoint ("subsearch:end::scope=%s;target=%s;query=%s", agg_scope.id, scope_id, search_string);
     return res;
   }
 
@@ -190,11 +190,9 @@
     if (search_context.cancellable.is_cancelled ()) return;
     var agg_scope = owner as AggregatorScope;
     var canc = search_context.cancellable.get_gcancellable ();
-    Unity.Trace.tracepoint ("%s start: %s", Log.METHOD, scope_id);
     yield agg_scope.push_results (channel_id, search_string,
                                   scope_id, results_model,
                                   category_ids, canc);
-    Unity.Trace.tracepoint ("%s end: %s", Log.METHOD, scope_id);
   }
 
   public void push_filter_settings (FilterSet filters)
 
=== modified file 'src/unity-synchronizer.vala'
--- src/unity-synchronizer.vala	2013-05-10 12:14:18 +0000
+++ src/unity-synchronizer.vala	2013-10-25 14:15:10 +0000
@@ -38,6 +38,7 @@
   }
 
   public unowned Dee.Model receiver { get; construct; }
+  public string owner_scope_id { get; construct; }
   public MergeStrategy merge_strategy { get; set; }
 
   private Gee.Set<Dee.Model> _providers;
@@ -50,9 +51,9 @@
   private Quark scope_id_quark = Quark.from_string ("scope-id");
   private uint _clear_seq_num = 1;
 
-  internal ResultsSynchronizer (Dee.Model receiver)
+  internal ResultsSynchronizer (Dee.Model receiver, string scope_id)
   {
-    Object (receiver:receiver);
+    Object (receiver:receiver, owner_scope_id: scope_id);
   }
 
   construct
@@ -184,9 +185,11 @@
   private void transaction_finished (Dee.SharedModel model,
                                      uint64 begin_sn, uint64 end_sn)
   {
+    unowned string scope_id = model.get_qdata<string> (scope_id_quark);
+    Unity.Trace.tracepoint ("changeset::scope=%s;target=%s", owner_scope_id, scope_id);
     if (model in _providers)
     {
-      transaction_complete (model, model.get_qdata<string> (scope_id_quark));
+      transaction_complete (model, scope_id);
     }
   }
 
 
=== modified file 'src/unity-trace.c'
--- src/unity-trace.c	2013-04-04 06:49:22 +0000
+++ src/unity-trace.c	2013-10-25 14:15:10 +0000
@@ -58,14 +58,12 @@
   va_end (args);
 }
 
-#ifdef ENABLE_LTTNG
-
 void
-unity_trace_tracepoint_real (const gchar *format, va_list args)
+unity_trace_tracepoint_va (const gchar *format, va_list args)
 {
+#ifdef ENABLE_LTTNG
   gchar *tmp = g_strdup_vprintf (format, args);
   tracepoint (libunity, message, tmp);
   g_free (tmp);
+#endif
 }
-
-#endif
 
=== modified file 'src/unity-trace.h'
--- src/unity-trace.h	2013-04-04 11:47:25 +0000
+++ src/unity-trace.h	2013-10-25 14:15:10 +0000
@@ -90,11 +90,13 @@
 #endif /* ENABLE_UNITY_TRACE_LOG */
 
 #ifdef ENABLE_LTTNG
+void     unity_trace_tracepoint_va (const gchar *format, va_list args);
+
 static void unity_trace_tracepoint (const gchar *format, ...)
 {
   va_list args;
   va_start (args, format);
-  unity_trace_tracepoint_real (format, args);
+  unity_trace_tracepoint_va (format, args);
   va_end (args);
 }
 #else
 
=== modified file 'test/vala/Makefile.am'
--- test/vala/Makefile.am	2013-07-04 23:07:03 +0000
+++ test/vala/Makefile.am	2013-10-25 14:15:10 +0000
@@ -52,7 +52,12 @@
 	$(top_builddir)/src/libunity.la \
 	$(top_builddir)/protocol/libunity-protocol-private.la \
 	$(top_builddir)/extras/libunity-extras.la \
-	$(LIBUNITY_LIBS)
+	$(LIBUNITY_LIBS) \
+	$(NULL)
+
+if ENABLE_LTTNG
+test_libs += -lurcu-bp
+endif
 
 TEST_PROGS += test-vala test-scope test-blacklist-crash test-extras
 
@@ -86,6 +91,8 @@
 nodist_test_blacklist_crash_SOURCES = $(test_blacklist_crash_VALASOURCES:.vala=.c)
 
 test_extras_LDADD = $(test_libs)
+test_extras_LDFLAGS = -static
+
 test_extras_VALASOURCES = \
 	test-preview-player-iface.vala \
 	test-utils.vala \
 
=== modified file 'test/vala/test-results-synchronizer.vala'
--- test/vala/test-results-synchronizer.vala	2013-02-26 14:04:40 +0000
+++ test/vala/test-results-synchronizer.vala	2013-10-25 14:15:10 +0000
@@ -40,7 +40,7 @@
       var provider2 = new Dee.SequenceModel ();
       provider2.set_schema_full (RESULTS_SCHEMA);
       provider2.set_data<string> ("scope-id", "scope2");
-      var res_sync = new Internal.ResultsSynchronizer (receiver);
+      var res_sync = new Internal.ResultsSynchronizer (receiver, "master.scope");
       res_sync.add_provider (provider1, "scope1");
       res_sync.add_provider (provider2, "scope2");
 
 
=== added file 'tools/capture-trace.py'
--- tools/capture-trace.py	1970-01-01 00:00:00 +0000
+++ tools/capture-trace.py	2013-10-25 14:15:10 +0000
@@ -0,0 +1,225 @@
+#!/usr/bin/env python
+
+import os, sys
+import subprocess
+import re
+
+"""
+# This script has two modes of operation:
+#
+# 1) Capture a trace and generate a html visualization.
+#    To use this mode just run `./capture_trace.py`. This will setup a lttng
+#    session, enable all userspace trace events and spawns a subshell where
+#    you can for example run libunity-tool to perform a search on a scope.
+#    When the subshell exits, tracing is stopped and visualization is generated.
+#
+# 2) Only generate a html visualization of a previously captured trace.
+#    Use `./capture_trace.py /path/to/lttng/trace_dir`.
+#
+# Note that use use the first mode you need to have lttng installed
+# and libunity compiled with --enable-lttng option.
+# Required packages (besides requirements for libunity's --enable-lttng):
+# sudo apt-get install lttng-tools babeltrace
+"""
+
+"""
+# --- Manually capturing a trace
+# lttng create session_name
+# lttng enable-event -u -a
+# lttng start
+# --- start home scope with lttng-enabled branch of libunity, perform a search
+# lttng stop
+# lttng destroy
+# --- view the trace in cli
+# babeltrace ~/lttng_traces/<session_name dir>
+"""
+def capture_lttng_trace():
+    session = subprocess.check_output(["lttng", "create", "libunity-trace"], stdin=subprocess.PIPE)
+    trace_started = False
+    try:
+        subprocess.check_output(["lttng", "enable-event", "-u", "-a"], stdin=subprocess.PIPE)
+        subprocess.check_output(["lttng", "start"], stdin=subprocess.PIPE)
+        trace_started = True
+        sys.stderr.write("Trace running... Close this sub-shell with Ctrl+D to finish\n")
+        subprocess.check_call(["bash"]) # let this inherit our stdin
+    except subprocess.CalledProcessError as cpe:
+        if trace_started:
+            # bash will return non-zero exit code if you for example Ctrl+C
+            # a program within it, let's just ignore those errors
+            msg = "Warning: subshell returned error: " + str(cpe.returncode)
+            sys.stderr.write(msg + "\n")
+        else: raise
+    finally:
+        if trace_started:
+            subprocess.check_output(["lttng", "stop"], stdin=subprocess.PIPE)
+        subprocess.check_output(["lttng", "destroy", "libunity-trace"], stdin=subprocess.PIPE)
+
+    match = re.findall(r'Traces will be written in (.+)', session)
+    if len(match) > 0: return match[0]
+    return None
+
+# trace event example
+"""
+[20:00:30.697493680] (+0.000014138) miso-ThinkPad:unity-scope-hom:26439 libunity:message: { cpu_id = 0 }, { message = "flush::com.canonical.Unity.Master.Scope.home.T296521243842038" }
+"""
+
+def parse_trace_line(line):
+    pattern = re.compile(r'^\[(?P<timestamp>[0-9:\.]+)\].+?{ message = "(?P<msg>[^"]+)"')
+    match = pattern.match(line)
+    timestamp = match.group("timestamp")
+    msg = match.group("msg")
+    msg_parts = msg.split("::", 2)
+    if len(msg_parts) > 1:
+        msg_type = msg_parts[0]
+        msg = {}
+        for kv in msg_parts[1].split(";"):
+            items = kv.split("=", 2)
+            if len(items) > 1:
+                msg[items[0]] = items[1]
+            else:
+                msg['content'] = items[0]
+    else:
+        msg_type = "other"
+        msg = {'content': msg}
+
+    return (timestamp, msg_type, msg)
+
+def find_end_event(events, searched_event, event_type):
+    for i in range(len(events)):
+        event = events[i]
+        if event[1] == event_type and event[2] == searched_event[2]:
+            return i
+    return -1
+
+def pair_events(events):
+    paired = []
+    i = 0
+    while i < len(events):
+        event = events[i]
+        event_type = event[1]
+        if event_type.endswith(":start"):
+            group = event[1].split(":", 2)[0]
+            j = find_end_event(events[i+1:], event, group + ":end")
+            if j >= 0:
+                end_event = events.pop(i+j+1)
+                paired.append((event, end_event))
+                i = i+1
+                continue
+        paired.append((event, None))
+        i = i+1
+
+    return paired
+
+COLOR_FOR_EVENT = {
+    'search': "'#394a6b'",
+    'subsearch': "'#109618'",
+    'changeset': "'#990099'",
+    'diff': "'#e57357'",
+    'flush': "'#ff9900'",
+    'push': "'#0099c6'"
+}
+
+def produce_html(trace_name, pairs):
+    base = """<html><head><title>%s</title></head><body>
+<script type="text/javascript" src="https://www.google.com/jsapi?autoload={'modules':[{'name':'visualization',
+       'version':'1','packages':['timeline']}]}"></script>
+<script type="text/javascript">
+
+google.setOnLoadCallback(drawChart);
+function drawChart() {
+  var dataTable = new google.visualization.DataTable();
+
+  dataTable.addColumn({ type: 'string', id: 'group' });
+  dataTable.addColumn({ type: 'string', id: 'id' });
+  dataTable.addColumn({ type: 'string', id: 'data' });
+  dataTable.addColumn({ type: 'datetime', id: 'Start' });
+  dataTable.addColumn({ type: 'datetime', id: 'End' });
+
+  dataTable.addRows([
+    %s
+  ]);
+
+  var view = new google.visualization.DataView(dataTable);
+  view.setColumns([0,1,3,4]);
+
+  var container = document.getElementById('example2.1');
+  var chart = new google.visualization.Timeline(container);
+
+  chart.draw(view);
+}
+</script>
+
+<div id="example2.1" style="height: 100%%;"></div>
+</body></html>"""
+    rows = []
+    colors = []
+    for pair in pairs:
+        (start_event, end_event) = pair
+        (timestamp, event_type, metadata) = start_event
+        has_end_ts = end_event is not None
+
+        group = event_type if not event_type.endswith(":start") else event_type.split(":", 2)[0]
+        color = COLOR_FOR_EVENT[group] if group in COLOR_FOR_EVENT else "'#c60000'"
+        has_scope_id = 'scope' in metadata
+        scope_id = metadata['scope'] if has_scope_id else metadata['content']
+        if has_scope_id: del metadata['scope']
+        else:
+            if group in ['changeset', 'flush', 'diff']:
+                match = re.match(r'com.canonical.Unity\.Master\.Scope\.(\w+)\.T', scope_id)
+                if match: scope_id = "%s.scope" % match.group(1)
+        data = str(metadata).replace("'", "\\'")
+
+        # we're loosing our lovely nanosecond precision :(
+        map_to_int = lambda x: int(x[0:3])
+        start_date = map(map_to_int, re.findall(r'\d+', timestamp))
+        end_date = start_date
+        if has_end_ts:
+            end_date = map(map_to_int, re.findall(r'\d+', end_event[0]))
+
+        event_name = "%s - %s" % (group, metadata['target']) if 'target' in metadata else group
+        data_tuple = (scope_id, group, data, ",".join(map(str,start_date)), ",".join(map(str, end_date)))
+        data_format = "[ '%s', '%s', '%s', new Date(0,0,0,%s), new Date(0,0,0,%s) ]"
+        data_row = data_format % data_tuple
+        rows.append(data_row)
+        colors.append(color)
+    return base % ("Analysis of %s" % trace_name, ",\n".join(rows))
+
+def get_events_from_babeltrace(trace_dir):
+    events = []
+    all_events = subprocess.check_output(["babeltrace", trace_dir])
+    lines = filter(None, all_events.split("\n"))
+    for line in lines:
+        event = parse_trace_line(line)
+        events.append(event)
+    return events
+
+def main(args):
+    output_name = None
+    if len(args) > 1:
+        trace_dir = args[1]
+    else:
+        trace_dir = capture_lttng_trace()
+
+    if trace_dir:
+        basename = os.path.basename(trace_dir)
+        if not basename:
+            basename = os.path.basename(os.path.dirname(trace_dir))
+        output_name = "%s.html" % basename
+
+    events = get_events_from_babeltrace(trace_dir)
+    if len(events) == 0:
+        raise RuntimeError("There are 0 events in the trace")
+    pairs = pair_events(events)
+    html = produce_html(trace_dir, pairs)
+
+    if output_name:
+        sys.stderr.write("Writing output to '%s'\n" % output_name)
+        f = open(output_name, 'w')
+        f.write(html)
+        f.close()
+    else:
+        print html
+
+if __name__ == "__main__":
+    main (sys.argv)
+
 
=== modified file 'tools/unity-tool.vala'
--- tools/unity-tool.vala	2013-10-04 16:08:32 +0000
+++ tools/unity-tool.vala	2013-10-25 14:15:10 +0000
@@ -35,6 +35,7 @@
     public static bool print_search_reply;
     public static bool dump_results;
     public static bool dump_filters;
+    public static bool diff_changes;
 
     public static bool test_server_mode;
     public static string[] test_cases;
@@ -104,6 +105,10 @@
       "Use private channel for results transfer", null
     },
     {
+      "diff-changes", 'd', 0, OptionArg.NONE, out Options.diff_changes,
+      "Use diff channel", null
+    },
+    {
       "test-server-mode", 0, 0, OptionArg.NONE, out Options.test_server_mode,
       "Run a collection of test scripts", null
     },
@@ -238,12 +243,10 @@
         // Get proxy
         string channel_id;
         Dee.SerializableModel results_model;
-        var flags = Options.private_channel ?
-          ChannelFlags.PRIVATE : ChannelFlags.NONE;
         var proxy = get_scope_proxy (Options.scope_dbus_name,
                                      Options.scope_dbus_path,
                                      (ChannelType) Options.search_type,
-                                     flags,
+                                     get_global_channel_flags (),
                                      out channel_id, out results_model);
 
         // Performing search
@@ -508,18 +511,24 @@
     return Test.run ();
   }
 
+  private static ChannelFlags get_global_channel_flags ()
+  {
+    var flags = ChannelFlags.NONE;
+    if (Options.private_channel) flags |= ChannelFlags.PRIVATE;
+    if (Options.diff_changes) flags |= ChannelFlags.DIFF_CHANGES;
+    return flags;
+  }
+
   private static void call_scope_search (string search_string,
                                          int search_type)
   {
     string channel_id;
     Dee.SerializableModel results_model;
 
-    var flags = Options.private_channel ?
-      ChannelFlags.PRIVATE : ChannelFlags.NONE;
     var proxy = get_scope_proxy (Options.scope_dbus_name,
                                  Options.scope_dbus_path,
                                  (ChannelType) search_type,
-                                 flags,
+                                 get_global_channel_flags (),
                                  out channel_id, out results_model);
 
     var ml = new MainLoop ();