perf-tool: Spawn perf-tool-helper from gnome-shell

On Wayland, the display server is the Wayland compositor, i.e.
`gnome-shell` itself.

As a result, we cannot spawn `gnome-shell-perf-helper` before
`gnome-shell` is started, as `gnome-shell-perf-helper` needs to connect
to the display server.

So, instead of spawning `gnome-shell-perf-helper` from the perf tool,
start it from `gnome-shell` itself.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/941

js/ui/scripting.js

@@ -5,8 +5,10 @@
 
 const { Gio, GLib, Meta, Shell } = imports.gi;
 
+const Config = imports.misc.config;
 const Main = imports.ui.main;
 const Params = imports.misc.params;
+const Util = imports.misc.util;
 
 const { loadInterfaceXML } = imports.misc.fileUtils;
 
@@ -77,6 +79,12 @@ function _getPerfHelper() {
     return _perfHelper;
 }
 
+function _spawnPerfHelper() {
+    let path = Config.LIBEXECDIR;
+    let command = `${path}/gnome-shell-perf-helper`;
+    Util.trySpawnCommandLine(command);
+}
+
 function _callRemote(obj, method, ...args) {
     return new Promise((resolve, reject) => {
         args.push((result, excp) => {
@@ -276,6 +284,25 @@ function _collect(scriptModule, outputFile) {
     }
 }
 
+async function _runPerfScript(scriptModule, outputFile) {
+    for (let step of scriptModule.run()) {
+        try {
+            await step; // eslint-disable-line no-await-in-loop
+        } catch (err) {
+            log(`Script failed: ${err}\n${err.stack}`);
+            Meta.exit(Meta.ExitCode.ERROR);
+        }
+    }
+
+    try {
+        _collect(scriptModule, outputFile);
+    } catch (err) {
+        log(`Script failed: ${err}\n${err.stack}`);
+        Meta.exit(Meta.ExitCode.ERROR);
+    }
+    Meta.exit(Meta.ExitCode.SUCCESS);
+}
+
 /**
  * runPerfScript
  * @param {Object} scriptModule: module object with run and finish
@@ -317,23 +344,13 @@ function _collect(scriptModule, outputFile) {
  * After running the script and collecting statistics from the
  * event log, GNOME Shell will exit.
  **/
-async function runPerfScript(scriptModule, outputFile) {
+function runPerfScript(scriptModule, outputFile) {
     Shell.PerfLog.get_default().set_enabled(true);
+    _spawnPerfHelper();
 
-    for (let step of scriptModule.run()) {
+    Gio.bus_watch_name(Gio.BusType.SESSION,
-        try {
+        'org.gnome.Shell.PerfHelper',
-            await step; // eslint-disable-line no-await-in-loop
+        Gio.BusNameWatcherFlags.NONE,
-        } catch (err) {
+        () => _runPerfScript(scriptModule, outputFile),
-            log(`Script failed: ${err}\n${err.stack}`);
+        null);
-            Meta.exit(Meta.ExitCode.ERROR);
-        }
-    }
-
-    try {
-        _collect(scriptModule, outputFile);
-    } catch (err) {
-        log(`Script failed: ${err}\n${err.stack}`);
-        Meta.exit(Meta.ExitCode.ERROR);
-    }
-    Meta.exit(Meta.ExitCode.SUCCESS);
 }

src/gnome-shell-perf-tool.in

@@ -24,52 +24,6 @@ def show_version(option, opt_str, value, parser):
     print("GNOME Shell Performance Test @VERSION@")
     sys.exit()
 
-def wait_for_dbus_name(wait_name):
-    loop = GLib.MainLoop()
-
-    def on_name_appeared(connection, name, new_owner, *args):
-        if not (name == wait_name and new_owner != ''):
-            return
-        loop.quit()
-        return
-
-    watch_id = Gio.bus_watch_name(Gio.BusType.SESSION,
-                                  wait_name,
-                                  Gio.BusNameWatcherFlags.NONE,
-                                  on_name_appeared,
-                                  None)
-
-    def on_timeout():
-        print("\nFailed to start %s: timed out" % (wait_name,))
-        sys.exit(1)
-    GLib.timeout_add_seconds(7, on_timeout)
-
-    loop.run()
-    Gio.bus_unwatch_name(watch_id)
-
-PERF_HELPER_NAME = "org.gnome.Shell.PerfHelper"
-PERF_HELPER_IFACE = "org.gnome.Shell.PerfHelper"
-PERF_HELPER_PATH = "/org/gnome/Shell/PerfHelper"
-
-def start_perf_helper():
-    self_dir = os.path.dirname(os.path.abspath(sys.argv[0]))
-    perf_helper_path = "@libexecdir@/gnome-shell-perf-helper"
-
-    subprocess.Popen([perf_helper_path])
-    wait_for_dbus_name (PERF_HELPER_NAME)
-
-def stop_perf_helper():
-    bus = Gio.bus_get_sync(Gio.BusType.SESSION, None)
-
-    proxy = Gio.DBusProxy.new_sync(bus,
-                                   Gio.DBusProxyFlags.NONE,
-                                   None,
-                                   PERF_HELPER_NAME,
-                                   PERF_HELPER_PATH,
-                                   PERF_HELPER_IFACE,
-                                   None)
-    proxy.Exit()
-
 def start_shell(perf_output=None):
     # Set up environment
     env = dict(os.environ)
@@ -204,8 +158,6 @@ def run_performance_test():
     logs = []
     metric_summaries = {}
 
-    start_perf_helper()
-
     for i in range(0, iters):
         # We create an empty temporary file that the shell will overwrite
         # with the contents.
@@ -217,14 +169,12 @@ def run_performance_test():
         try:
             normal_exit = run_shell(perf_output=output_file)
         except:
-            stop_perf_helper()
             raise
         finally:
             if not normal_exit:
                 os.remove(output_file)
 
         if not normal_exit:
-            stop_perf_helper()
             return False
 
         try:
@@ -232,7 +182,6 @@ def run_performance_test():
             output = json.load(f)
             f.close()
         except:
-            stop_perf_helper()
             raise
         finally:
             os.remove(output_file)
@@ -260,8 +209,6 @@ def run_performance_test():
 
         logs.append(output['log'])
 
-    stop_perf_helper()
-
     if options.perf_output or options.perf_upload:
         # Write a complete report, formatted as JSON. The Javascript/C code that
         # generates the individual reports we are summarizing here is very careful