Start incremental marking in long idle notification for background tab

src/heap/memory-reducer.cc

 // Copyright 2015 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/heap/memory-reducer.h"
 
 #include "src/flags.h"
 #include "src/heap/heap.h"
 #include "src/utils.h"
 #include "src/v8.h"
@@ skipping 64 matching lines @@
   DCHECK_EQ(kContextDisposed, event.type);
   Action old_action = state_.action;
   state_ = Step(state_, event);
   if (old_action != kWait && state_.action == kWait) {
     // If we are transitioning to the WAIT state, start the timer.
     ScheduleTimer(state_.next_gc_start_ms - event.time_ms);
   }
 }
 
 
+void MemoryReducer::NotifyBackgroundIdleNotification(const Event& event) {
+  DCHECK_EQ(kBackgroundIdleNotification, event.type);
+  Action old_action = state_.action;
+  int old_started_gcs = state_.started_gcs;
+  state_ = Step(state_, event);
+  if (old_action == kWait && state_.action == kWait &&
+      old_started_gcs + 1 == state_.started_gcs) {
+    DCHECK(heap()->incremental_marking()->IsStopped());
+    DCHECK(FLAG_incremental_marking);
+    heap()->StartIdleIncrementalMarking();
+    if (FLAG_trace_gc_verbose) {
+      PrintIsolate(heap()->isolate(),
+                   "Memory reducer: started GC #%d"
+                   " (background idle)\n",
+                   state_.started_gcs);
+    }
+  }
+}
+
+
 // For specification of this function see the comment for MemoryReducer class.
 MemoryReducer::State MemoryReducer::Step(const State& state,
                                          const Event& event) {
   if (!FLAG_incremental_marking) {
     return State(kDone, 0, 0);
   }
   switch (state.action) {
     case kDone:
-      if (event.type == kTimer) {
+      if (event.type == kTimer || event.type == kBackgroundIdleNotification) {
         return state;
       } else {
         DCHECK(event.type == kContextDisposed || event.type == kMarkCompact);
         return State(kWait, 0, event.time_ms + kLongDelayMs);
       }
     case kWait:
-      if (event.type == kContextDisposed) {
-        return state;
-      } else if (event.type == kTimer && event.can_start_incremental_gc &&
-                 event.low_allocation_rate) {
-        if (state.next_gc_start_ms <= event.time_ms) {
-          return State(kRun, state.started_gcs + 1, 0.0);
-        } else {
+      switch (event.type) {
+        case kContextDisposed:
           return state;
-        }
-      } else {
-        return State(kWait, state.started_gcs, event.time_ms + kLongDelayMs);
+        case kTimer:
+          if (state.started_gcs >= kMaxNumberOfGCs) {
+            return State(kDone, 0, 0.0);
+          } else if (event.can_start_incremental_gc &&
+                     event.low_allocation_rate) {
+            if (state.next_gc_start_ms <= event.time_ms) {
+              return State(kRun, state.started_gcs + 1, 0.0);
+            } else {
+              return state;
+            }
+          } else {
+            return State(kWait, state.started_gcs,
+                         event.time_ms + kLongDelayMs);
+          }
+        case kBackgroundIdleNotification:
+          if (event.can_start_incremental_gc &&
+              state.started_gcs < kMaxNumberOfGCs) {
+            return State(kWait, state.started_gcs + 1,
+                         event.time_ms + kLongDelayMs);
+          } else {
+            return state;
+          }
+        case kMarkCompact:
+          return State(kWait, state.started_gcs, event.time_ms + kLongDelayMs);
       }
     case kRun:
       if (event.type != kMarkCompact) {
         return state;
       } else {
         if (state.started_gcs < kMaxNumberOfGCs &&
             (event.next_gc_likely_to_collect_more || state.started_gcs == 1)) {
           return State(kWait, state.started_gcs, event.time_ms + kShortDelayMs);
         } else {
           return State(kDone, 0, 0.0);
@@ skipping 10 matching lines @@
   // Leave some room for precision error in task scheduler.
   const double kSlackMs = 100;
   v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(heap()->isolate());
   V8::GetCurrentPlatform()->CallDelayedOnForegroundThread(
       isolate, new MemoryReducer::TimerTask(this),
       (delay_ms + kSlackMs) / 1000.0);
 }
 
 }  // internal
 }  // v8