Hook up link pools in GN.

tools/gn/ninja_build_writer.cc

 // Copyright (c) 2013 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 "tools/gn/ninja_build_writer.h"
 
 #include <fstream>
 #include <map>
 
 #include "base/command_line.h"
@@ skipping 57 matching lines @@
 #else
   return cmdline.GetCommandLineString();
 #endif
 }
 
 }  // namespace
 
 NinjaBuildWriter::NinjaBuildWriter(
     const BuildSettings* build_settings,
     const std::vector<const Settings*>& all_settings,
+    const Toolchain* default_toolchain,
     const std::vector<const Target*>& default_toolchain_targets,
     std::ostream& out,
     std::ostream& dep_out)
     : build_settings_(build_settings),
       all_settings_(all_settings),
+      default_toolchain_(default_toolchain),
       default_toolchain_targets_(default_toolchain_targets),
       out_(out),
       dep_out_(dep_out),
       path_output_(build_settings->build_dir(), ESCAPE_NINJA) {
 }
 
 NinjaBuildWriter::~NinjaBuildWriter() {
 }
 
 void NinjaBuildWriter::Run() {
   WriteNinjaRules();
+  WriteLinkPool();
   WriteSubninjas();
   WritePhonyAndAllRules();
 }
 
 // static
 bool NinjaBuildWriter::RunAndWriteFile(
     const BuildSettings* build_settings,
     const std::vector<const Settings*>& all_settings,
+    const Toolchain* default_toolchain,
     const std::vector<const Target*>& default_toolchain_targets) {
   ScopedTrace trace(TraceItem::TRACE_FILE_WRITE, "build.ninja");
 
   base::FilePath ninja_file(build_settings->GetFullPath(
       SourceFile(build_settings->build_dir().value() + "build.ninja")));
   base::CreateDirectory(ninja_file.DirName());
 
   std::ofstream file;
   file.open(FilePathToUTF8(ninja_file).c_str(),
             std::ios_base::out | std::ios_base::binary);
   if (file.fail())
     return false;
 
   std::ofstream depfile;
   depfile.open((FilePathToUTF8(ninja_file) + ".d").c_str(),
                std::ios_base::out | std::ios_base::binary);
   if (depfile.fail())
     return false;
 
-  NinjaBuildWriter gen(build_settings, all_settings,
+  NinjaBuildWriter gen(build_settings, all_settings, default_toolchain,
                        default_toolchain_targets, file, depfile);
   gen.Run();
   return true;
 }
 
 void NinjaBuildWriter::WriteNinjaRules() {
   out_ << "rule gn\n";
   out_ << "  command = " << GetSelfInvocationCommand(build_settings_) << "\n";
   out_ << "  description = Regenerating ninja files\n\n";
 
@@ skipping 13 matching lines @@
     dep_out_ << " " << FilePathToUTF8(input_files[i]);
 
   // Other files read by the build.
   std::vector<base::FilePath> other_files = g_scheduler->GetGenDependencies();
   for (size_t i = 0; i < other_files.size(); i++)
     dep_out_ << " " << FilePathToUTF8(other_files[i]);
 
   out_ << std::endl;
 }
 
+void NinjaBuildWriter::WriteLinkPool() {
+  out_ << "pool link_pool\n"
+       << "  depth = " << default_toolchain_->concurrent_links() << std::endl
+       << std::endl;
+}
+
 void NinjaBuildWriter::WriteSubninjas() {
   for (size_t i = 0; i < all_settings_.size(); i++) {
     out_ << "subninja ";
     path_output_.WriteFile(out_, GetNinjaFileForToolchain(all_settings_[i]));
     out_ << std::endl;
   }
   out_ << std::endl;
 }
 
 void NinjaBuildWriter::WritePhonyAndAllRules() {
@@ skipping 80 matching lines @@
   EscapeOptions ninja_escape;
   ninja_escape.mode = ESCAPE_NINJA;
 
   // Escape for special chars Ninja will handle.
   std::string escaped = EscapeString(phony_name, ninja_escape, NULL);
 
   out_ << "build " << escaped << ": phony ";
   path_output_.WriteFile(out_, target_file);
   out_ << std::endl;
 }