Use idle time to make progress on scheduled compilation jobs

src/compiler-dispatcher/compiler-dispatcher-job.cc

 // Copyright 2016 the V8 project 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 "src/compiler-dispatcher/compiler-dispatcher-job.h"
 
 #include "src/assert-scope.h"
 #include "src/compilation-info.h"
 #include "src/compiler-dispatcher/compiler-dispatcher-tracer.h"
 #include "src/compiler.h"
@@ skipping 245 matching lines @@
   compile_job_.reset();
 
   if (!source_.is_null()) {
     i::GlobalHandles::Destroy(Handle<Object>::cast(source_).location());
     source_ = Handle<String>::null();
   }
 
   status_ = CompileJobStatus::kInitial;
 }
 
+double CompilerDispatcherJob::EstimateRuntimeOfNextStepInMs() const {
+  switch (status_) {
+    case CompileJobStatus::kInitial:
+      return tracer_->EstimatePrepareToParseInMs();
+
+    case CompileJobStatus::kReadyToParse:
+      return tracer_->EstimateParseInMs(parse_info_->end_position() -
+                                        parse_info_->start_position());
+
+    case CompileJobStatus::kParsed:
+      return tracer_->EstimateFinalizeParsingInMs();
+
+    case CompileJobStatus::kReadyToAnalyse:
+      return tracer_->EstimatePrepareToCompileInMs();
+
+    case CompileJobStatus::kReadyToCompile:
+      return tracer_->EstimateCompileInMs(
+          parse_info_->literal()->ast_node_count());
+
+    case CompileJobStatus::kCompiled:
+      return tracer_->EstimateFinalizeCompilingInMs();
+
+    case CompileJobStatus::kFailed:
+    case CompileJobStatus::kDone:
+      return 0.0;
+  }
+
+  UNREACHABLE();
+  return 0.0;
+}
+
 }  // namespace internal
 }  // namespace v8