[heap] Divide available memory upon compaction tasks

src/heap/spaces.cc

Index: src/heap/spaces.cc
diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index 50a213e8ae4f582a3a684b4639c73894616fb851..5c1784f2cc80d74512805ba529dcd2d0a32e7dae 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -982,6 +982,101 @@ void PagedSpace::TearDown() {
 }
 
 
+void PagedSpace::AddMemory(Address start, intptr_t size) {
+  accounting_stats_.ExpandSpace(static_cast<int>(size));
+  Free(start, static_cast<int>(size));
+}
+
+
+FreeSpace* PagedSpace::TryRemoveMemory(intptr_t size_in_bytes) {
+  FreeSpace* free_space = free_list()->TryRemoveMemory(size_in_bytes);
+  if (free_space != nullptr) {
+    accounting_stats_.DecreaseCapacity(free_space->size());
+  }
+  return free_space;
+}
+
+
+void PagedSpace::DivideUponCompactionSpaces(CompactionSpaceCollection** other,
+                                            int num, intptr_t limit) {
+  DCHECK_GT(num, 0);
+  DCHECK(other != nullptr);
+
+  if (limit == 0) limit = std::numeric_limits<intptr_t>::max();
+
+  EmptyAllocationInfo();
+
+  bool memory_available = true;
+  bool spaces_need_memory = true;
+  FreeSpace* node = nullptr;
+  CompactionSpace* current_space = nullptr;
+  // Iterate over spaces and memory as long as we have memory and there are
+  // spaces in need of some.
+  while (memory_available && spaces_need_memory) {
+    spaces_need_memory = false;
+    // Round-robin over all spaces.
+    for (int i = 0; i < num; i++) {
+      current_space = other[i]->Get(identity());
+      if (current_space->free_list()->available() < limit) {
+        // Space has not reached its limit. Try to get some memory.
+        spaces_need_memory = true;
+        node = TryRemoveMemory(limit - current_space->free_list()->available());
+        if (node != nullptr) {
+          CHECK(current_space->identity() == identity());
+          current_space->AddMemory(node->address(), node->size());
+        } else {
+          memory_available = false;
+          break;
+        }
+      }
+    }
+  }
+}
+
+
+void PagedSpace::RefillFreeList() {
+  MarkCompactCollector* collector = heap()->mark_compact_collector();
+  FreeList* free_list = nullptr;
+  if (this == heap()->old_space()) {
+    free_list = collector->free_list_old_space().get();
+  } else if (this == heap()->code_space()) {
+    free_list = collector->free_list_code_space().get();
+  } else if (this == heap()->map_space()) {
+    free_list = collector->free_list_map_space().get();
+  } else {
+    // Any PagedSpace might invoke RefillFreeList. We filter all but our old
+    // generation spaces out.
+    return;
+  }
+  DCHECK(free_list != nullptr);
+  intptr_t added = free_list_.Concatenate(free_list);
+  accounting_stats_.IncreaseCapacity(added);
+}
+
+
+void CompactionSpace::RefillFreeList() {
+  MarkCompactCollector* collector = heap()->mark_compact_collector();
+  FreeList* free_list = nullptr;
+  if (identity() == OLD_SPACE) {
+    free_list = collector->free_list_old_space().get();
+  } else if (identity() == CODE_SPACE) {
+    free_list = collector->free_list_code_space().get();
+  } else {
+    // Compaction spaces only represent old or code space.
+    UNREACHABLE();
+  }
+  DCHECK(free_list != nullptr);
+  intptr_t refilled = 0;
+  while (refilled < kCompactionMemoryWanted) {
+    FreeSpace* node =
+        free_list->TryRemoveMemory(kCompactionMemoryWanted - refilled);
+    if (node == nullptr) return;
+    refilled += node->size();
+    AddMemory(node->address(), node->size());
+  }
+}
+
+
 void PagedSpace::MoveOverFreeMemory(PagedSpace* other) {
   DCHECK(identity() == other->identity());
   // Destroy the linear allocation space of {other}. This is needed to
@@ -994,8 +1089,7 @@ void PagedSpace::MoveOverFreeMemory(PagedSpace* other) {
   intptr_t added = free_list_.Concatenate(other->free_list());
 
   // Moved memory is not recorded as allocated memory, but rather increases and
-  // decreases capacity of the corresponding spaces. Used size and waste size
-  // are maintained by the receiving space upon allocating and freeing blocks.
+  // decreases capacity of the corresponding spaces.
   other->accounting_stats_.DecreaseCapacity(added);
   accounting_stats_.IncreaseCapacity(added);
 }
@@ -1004,16 +1098,19 @@ void PagedSpace::MoveOverFreeMemory(PagedSpace* other) {
 void PagedSpace::MergeCompactionSpace(CompactionSpace* other) {
   // Unmerged fields:
   //   area_size_
-  //   allocation_info_
-  //   end_of_unswept_pages_
-  //   unswept_free_bytes_
   //   anchor_
 
   MoveOverFreeMemory(other);
 
   // Update and clear accounting statistics.
   accounting_stats_.Merge(other->accounting_stats_);
-  other->accounting_stats_.Reset();
+  other->accounting_stats_.Clear();
+
+  // The linear allocation area of {other} should be destroyed now.
+  DCHECK(other->top() == nullptr);
+  DCHECK(other->limit() == nullptr);
+
+  DCHECK(other->end_of_unswept_pages_ == nullptr);
 
   AccountCommitted(other->CommittedMemory());
 
@@ -2392,6 +2489,28 @@ FreeSpace* FreeList::FindNodeFor(int size_in_bytes, int* node_size) {
 }
 
 
+FreeSpace* FreeList::TryRemoveMemory(intptr_t hint_size_in_bytes) {
+  base::LockGuard<base::Mutex> guard(&mutex_);
+  FreeSpace* node = nullptr;
+  int node_size = 0;
+  // Try to find a node that fits exactly.
+  node = FindNodeFor(static_cast<int>(hint_size_in_bytes), &node_size);
+  // If no node could be found get as much memory as possible.
+  if (node == nullptr) node = FindNodeIn(kHuge, &node_size);
+  if (node == nullptr) node = FindNodeIn(kLarge, &node_size);
+  if (node != nullptr) {
+    // Give back left overs that were not required by {size_in_bytes}.
+    intptr_t aligned_size = RoundUp(hint_size_in_bytes, kPointerSize);
+    intptr_t left_over = node_size - aligned_size;
+    if (left_over > 0) {
+      Free(node->address() + aligned_size, static_cast<int>(left_over));
+      node->set_size(static_cast<int>(aligned_size));
+    }
+  }
+  return node;
+}
+
+
 // Allocation on the old space free list.  If it succeeds then a new linear
 // allocation space has been set up with the top and limit of the space.  If
 // the allocation fails then NULL is returned, and the caller can perform a GC
@@ -2627,7 +2746,7 @@ HeapObject* PagedSpace::SlowAllocateRaw(int size_in_bytes) {
   if (collector->sweeping_in_progress()) {
     // First try to refill the free-list, concurrent sweeper threads
     // may have freed some objects in the meantime.
-    collector->RefillFreeList(this);
+    RefillFreeList();
 
     // Retry the free list allocation.
     HeapObject* object = free_list_.Allocate(size_in_bytes);
@@ -2635,7 +2754,7 @@ HeapObject* PagedSpace::SlowAllocateRaw(int size_in_bytes) {
 
     // If sweeping is still in progress try to sweep pages on the main thread.
     int free_chunk = collector->SweepInParallel(this, size_in_bytes);
-    collector->RefillFreeList(this);
+    RefillFreeList();
     if (free_chunk >= size_in_bytes) {
       HeapObject* object = free_list_.Allocate(size_in_bytes);
       // We should be able to allocate an object here since we just freed that