Use background tasks for the compiler dispatcher

src/compiler-dispatcher/compiler-dispatcher.h

Index: src/compiler-dispatcher/compiler-dispatcher.h
diff --git a/src/compiler-dispatcher/compiler-dispatcher.h b/src/compiler-dispatcher/compiler-dispatcher.h
index fea141e22f970ff9112290707539ca5d4c574015..d99c259a6783641923d52f41b5df27a9f366c811 100644
--- a/src/compiler-dispatcher/compiler-dispatcher.h
+++ b/src/compiler-dispatcher/compiler-dispatcher.h
@@ -7,9 +7,12 @@
 
 #include <map>
 #include <memory>
+#include <set>
 #include <utility>
 
 #include "src/base/macros.h"
+#include "src/base/platform/condition-variable.h"
+#include "src/base/platform/mutex.h"
 #include "src/globals.h"
 #include "testing/gtest/include/gtest/gtest_prod.h"
 
@@ -59,11 +62,16 @@ class V8_EXPORT_PRIVATE CompilerDispatcher {
   typedef std::multimap<std::pair<int, int>,
                         std::unique_ptr<CompilerDispatcherJob>>
       JobMap;
+  class BackgroundTask;
   class IdleTask;
 
+  void EnsureNotOnBackground(CompilerDispatcherJob* job);
   bool IsEnabled() const;
   JobMap::const_iterator GetJobFor(Handle<SharedFunctionInfo> shared) const;
+  void ConsiderJobForBackgroundProcessing(CompilerDispatcherJob* job);
+  void ScheduleMoreBackgroundTasksIfNeeded();
   void ScheduleIdleTaskIfNeeded();
+  void DoBackgroundWork();
   void DoIdleWork(double deadline_in_seconds);
 
   Isolate* isolate_;
@@ -77,6 +85,29 @@ class V8_EXPORT_PRIVATE CompilerDispatcher {
   // as script id is not necessarily unique.
   JobMap jobs_;
 
+  // The following members can be accessed from any thread. Methods need to hold
+  // the mutex |mutex_| while accessing them.
+  base::Mutex mutex_;
+
+  // Number of currently scheduled BackgroundTask objects.
+  size_t num_scheduled_background_tasks_;
+
+  // Number of currently available CompilerDispatcherJobs that can be advanced
+  // on any thread.
+  size_t num_available_background_jobs_;
+
+  // The set of CompilerDispatcherJobs that can be advanced on any thread.
+  std::set<CompilerDispatcherJob*> pending_background_jobs_;
+
+  // The set of CompilerDispatcherJobs currently processed on background
+  // threads.
+  std::set<CompilerDispatcherJob*> running_background_jobs_;
+
+  // If not nullptr, then the main thread waits for the task processing
+  // this job, and blocks on the ConditionVariable main_thread_blocking_signal_.
+  CompilerDispatcherJob* main_thread_blocking_on_job_;
+  base::ConditionVariable main_thread_blocking_signal_;
+
   DISALLOW_COPY_AND_ASSIGN(CompilerDispatcher);
 };