Shared Raster Worker Threads

cc/base/switches.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 "cc/base/switches.h"
 
 #include "base/command_line.h"
+#include "base/strings/string_number_conversions.h"
 
 namespace cc {
 namespace switches {
 
 // On platforms where checkerboards are used, prefer background colors instead
 // of checkerboards.
 const char kBackgroundColorInsteadOfCheckerboard[] =
     "background-color-instead-of-checkerboard";
 
 // Disables LCD text.
@@ skipping 173 matching lines @@
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
   if (command_line.HasSwitch(cc::switches::kDisableMapImage))
     return false;
   else if (command_line.HasSwitch(cc::switches::kEnableMapImage))
     return true;
 
   return false;
 }
 
+int GetNumRasterThreads() {

[reveman, 2013/11/21 16:36:10]

nit: indent 2 spaces not 4

[reveman, 2013/11/21 16:36:10]

return size_t instead of int?

+    const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+    std::string string_value =
+        command_line.GetSwitchValueASCII(cc::switches::kNumRasterThreads);

[vivekg, 2013/11/21 17:18:12]

In case kNumRasterThreads command line switch is not provided, the string_value
would be empty. We can bailout early by using std::string::empty() and returning
the minimum  number i.e. 1.

[reveman, 2013/11/21 17:30:02]

Yes, please add a command_line.HasSwitch check and a kDefaultNumRasterThreads
constant that is returned when switch is not present.

+    int num_threads;
+    base::StringToInt(string_value, &num_threads);
+    if (num_threads == 0)
+        num_threads = 1;  // Min num of threads

[reveman, 2013/11/21 16:36:10]

we should also put a limit on the max number of threads. maybe you could do
something like this:

const int kMinRasterThreads = 1;
const int kMaxRasterThreads = 64;
return std::max(kMinRasterThreads, std::min(num_threads, kMaxRasterThreads));

+    return num_threads;
+}
+
 }  // namespace switches
 }  // namespace cc