Profiling: Enable profiling in code using google-perftools

meson.build

@@ -73,6 +73,40 @@ if get_option('development') and git.found ()
     branch = output.stdout().strip()
 endif
 
+# Profiler linking code taken from https://github.com/RidgeRun/gst-inference/blob/master/meson.build
+# with some amendments
+# 'libprofiler' and 'libtcmalloc' are provided by installing (e.g.) 'google-perftools' and 'libgoogle-pertools-dev'
+# Profiling is not active unless either the correct environment variables are set at runtime
+# or the profiling is switched on/off in the code using the CPU_PROFILING and HEAP_PROFILING conditional compilation flags
+# with the commands Profiler.start (<path-to-profile-output>) and Profiler.stop () and the corresponding HeapProfiler functions
+# It is advisable not to run cpu profiling at the same time as heap profiling
+# If meson options are changed then rebuild with 'cd .. && sudo rm -R ./build && build'
+# See https://github.com/gperftools/gperftools/blob/master/docs/cpuprofile.adoc
+# and https://github.com/gperftools/gperftools/blob/master/docs/heapprofile.adoc
+if get_option('cpu-profiling-enabled')
+  profiler_dep = dependency ('libprofiler')
+  if(profiler_dep.found())
+    message('CPU profiling enabled: Building with profiling support.')
+    add_global_link_arguments ('-lprofiler', language: 'c')
+    add_project_arguments ('--define=PROFILING', language: 'vala')
+    dependencies += profiler_dep
+  else
+    message('MESON_FAIL: CPU profiling requested but libprofiler (gperftools) not found.')
+  endif
+endif
+if get_option('heap-profiling-enabled')
+  heap_profiler_dep = dependency ('libtcmalloc')
+  if(heap_profiler_dep.found())
+    message('Heap profiling enabled: Building with heap profiling support.')
+    add_global_link_arguments ('-ltcmalloc', language: 'c')
+    add_project_arguments ('--define=HEAP_PROFILING', language: 'vala')
+    dependencies += heap_profiler_dep
+  else
+    message('MESON_FAIL: Heap profiling requested but libtcmalloc (gperftools) not found.')
+  endif
+endif
+
+
 subdir('data')
 subdir('src')
 if get_option('plugins')

meson_options.txt

@@ -1,3 +1,5 @@
 option('plugins', type : 'boolean', value : true)
 option('have_pkexec', type : 'boolean', value : true, description : 'Allow launching with pkexec. Should not be used in FlatPak')
 option('development', type : 'boolean', value : false, description : 'Build is a development branch')
+option('cpu-profiling-enabled', type : 'boolean', value : false, description: 'Enable cpu profiling')
+option('heap-profiling-enabled', type : 'boolean', value : false, description: 'Enable heap profiling')

src/Application.vala

@@ -200,7 +200,39 @@ namespace Scratch {
         }
 
         public static int main (string[] args) {
+// By default, profile whole app when profiling is enabled in meson_options.txt
+// These conditional statements can be moved to profile sections of code
+// The gperftools library must be installed (libgoogle-perftools-dev)
+// Amend the profile report paths as required
+#if PROFILING
+            // Visualize the cpu profile with e.g. google-pprof --functions --gv /usr/bin/io.elementary.code <profile_path>
+            // Use --focus=<regexp> and --ignore=<regexp> to filter/prune nodes displayed
+            var profile_path = Path.build_filename (Environment.get_home_dir (), "CpuProfileCodeApplication.prof");
+            // Start CPU profiling
+            Profiler.start (profile_path);
+            warning ("start cpu profiling - output to %s", profile_path);
+#endif
+#if HEAP_PROFILING
+            // NOTE: Heap profiling at this point slows the program down **a lot** It will take tens of seconds to load.
+            // The output path will have the suffix '.NNNN.heap' appended
+            // Visualize the profile with e.g. google-pprof --gv /usr/bin/io.elementary.code <profile_path>
+            // Use --focus=<regexp> and --ignore=<regexp> to filter/prune nodes displayed
+            var heap_profile_path = Path.build_filename (Environment.get_home_dir (), "HeapProfileCodeApplication");
+            // Start heap profiling
+            HeapProfiler.start (heap_profile_path);
+            warning ("start heap profiling - output to %s", heap_profile_path);
+#endif
+
             return new Application ().run (args);
+
+#if PROFILING
+            Profiler.stop ();
+            warning ("stop cpu profiling");
+#endif
+#if HEAP_PROFILING
+            HeapProfiler.stop ();
+            warning ("stop heap profiling");
+#endif
         }
     }
 }

vapi/libprofiler.vapi

@@ -0,0 +1,9 @@
+[CCode (cheader_filename = "gperftools/profiler.h")]
+namespace Profiler {
+    [CCode (cname = "ProfilerStart")]
+    public static void start (string path_to_output_file);
+    [CCode (cname = "ProfilerStop")]
+    public static void stop ();
+    [CCode (cname = "ProfilerFlush")]
+    public static void flush ();
+}

vapi/libtcmalloc.vapi

@@ -0,0 +1,9 @@
+[CCode (cheader_filename = "gperftools/heap-profiler.h")]
+namespace HeapProfiler {
+    [CCode (cname = "HeapProfilerStart")]
+    public static void start (string path_to_output_file_profix);
+    [CCode (cname = "HeapProfilerStop")]
+    public static void stop ();
+    [CCode (cname = "HeapProfilerDump")]
+    public static void dump (string reason);
+}