Disable timing from chrome://profiler on Android.

base/tracked_objects.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/tracked_objects.h"
 
 #include <limits.h>
 #include <stdlib.h>
 
+#include "base/base_switches.h"
+#include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/debug/leak_annotations.h"
 #include "base/logging.h"
 #include "base/process/process_handle.h"
 #include "base/profiler/alternate_timer.h"
 #include "base/strings/stringprintf.h"
 #include "base/third_party/valgrind/memcheck.h"
 #include "base/tracking_info.h"
 
 using base::TimeDelta;
@@ skipping 24 matching lines @@
 
 // Control whether an alternate time source (Now() function) is supported by
 // the ThreadData class.  This compile time flag should be set to true if we
 // want other modules (such as a memory allocator, or a thread-specific CPU time
 // clock) to be able to provide a thread-specific Now() function.  Without this
 // compile-time flag, the code will only support the wall-clock time.  This flag
 // can be flipped to efficiently disable this path (if there is a performance
 // problem with its presence).
 static const bool kAllowAlternateTimeSourceHandling = true;
 
+inline bool IsProfilerTimingEnabled() {
+  enum {

[no sievers, 2013/12/09 20:10:23]

missing static

[qsr, 2013/12/11 09:11:21]

Done.

+    UNDEFINED_TIMING,
+    ENABLED_TIMING,
+    DISABLED_TIMING,
+  } g_timing_enabled = UNDEFINED_TIMING;

[jar (doing other things), 2013/12/09 20:31:34]

It probably *should* be a global static per the g_* prefix, or something similar
in an anonymous file-scope namespace.  That way it won't bother with
initialization checking, rather than "just" a function static which would
(perchance with barriers etc.).

You'll probably get a thread sanitizer complaint... but that seems acceptable. 
If necessary, you could use atomics.

[Mark Mentovai, 2013/12/09 20:42:39]

jar wrote:
Yes, drop the g_ prefix and put on the “static” keyword as noted by sievers.
Huh?

How would access to a file-scoped static be handled any differently than access
to a function-scoped one? An integer constant-initialized static can be in BSS
or the data segment whether it’s file-scoped or function-scoped.

[jar (doing other things), 2013/12/09 20:47:55]

<doh>  My mistaken... function statics don't need the fancy handling when they
are known at link time... and are the same as file scope statics.  I don't know
what I was thinking.

[qsr, 2013/12/11 09:11:21]

Done.

+  // This initialization is not thread-safe, so the value of |g_timing_enabled|
+  // can be computed multiple times. This is not an issue, as the computed value
+  // will always be the same, and is side-effect free.
+  if (g_timing_enabled == UNDEFINED_TIMING) {
+    g_timing_enabled = (CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+                            switches::kProfilerTiming) ==
+                        switches::kProfilerTimingDisabledValue)
+                           ? DISABLED_TIMING
+                           : ENABLED_TIMING;
+  }
+  return g_timing_enabled == ENABLED_TIMING;
+}
+
 }  // namespace
 
 //------------------------------------------------------------------------------
 // DeathData tallies durations when a death takes place.
 
 DeathData::DeathData() {
   Clear();
 }
 
 DeathData::DeathData(int count) {
@@ skipping 683 matching lines @@
 void ThreadData::SetAlternateTimeSource(NowFunction* now_function) {
   DCHECK(now_function);
   if (kAllowAlternateTimeSourceHandling)
     now_function_ = now_function;
 }
 
 // static
 TrackedTime ThreadData::Now() {
   if (kAllowAlternateTimeSourceHandling && now_function_)
     return TrackedTime::FromMilliseconds((*now_function_)());
-  if (kTrackAllTaskObjects && TrackingStatus())
+  if (kTrackAllTaskObjects && IsProfilerTimingEnabled() && TrackingStatus())
     return TrackedTime::Now();
   return TrackedTime();  // Super fast when disabled, or not compiled.
 }
 
 // static
 void ThreadData::EnsureCleanupWasCalled(int major_threads_shutdown_count) {
   base::AutoLock lock(*list_lock_.Pointer());
   if (worker_thread_data_creation_count_ == 0)
     return;  // We haven't really run much, and couldn't have leaked.
   // Verify that we've at least shutdown/cleanup the major namesd threads.  The
@@ skipping 95 matching lines @@
     : process_id(base::GetCurrentProcId()) {
 #else
     : process_id(0) {
 #endif
 }
 
 ProcessDataSnapshot::~ProcessDataSnapshot() {
 }
 
 }  // namespace tracked_objects