Make store buffer more robust to OOM.

src/heap/store-buffer.cc

 // Copyright 2011 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 <algorithm>
 
 #include "src/v8.h"
 
 #include "src/counters.h"
 #include "src/heap/store-buffer-inl.h"
@@ skipping 15 matching lines @@
       store_buffer_rebuilding_enabled_(false),
       callback_(NULL),
       may_move_store_buffer_entries_(true),
       virtual_memory_(NULL),
       hash_set_1_(NULL),
       hash_set_2_(NULL),
       hash_sets_are_empty_(true) {}
 
 
 void StoreBuffer::SetUp() {
+  // Allocate 3x the buffer size, so that we can start the new store buffer
+  // aligned to 2x the size.  This lets us use a bit test to detect the end of
+  // the area.
   virtual_memory_ = new base::VirtualMemory(kStoreBufferSize * 3);
   uintptr_t start_as_int =
       reinterpret_cast<uintptr_t>(virtual_memory_->address());
   start_ =
       reinterpret_cast<Address*>(RoundUp(start_as_int, kStoreBufferSize * 2));
   limit_ = start_ + (kStoreBufferSize / kPointerSize);
 
+  // Reserve space for the larger old buffer.
   old_virtual_memory_ =
       new base::VirtualMemory(kOldStoreBufferLength * kPointerSize);
   old_top_ = old_start_ =
       reinterpret_cast<Address*>(old_virtual_memory_->address());
   // Don't know the alignment requirements of the OS, but it is certainly not
   // less than 0xfff.
-  DCHECK((reinterpret_cast<uintptr_t>(old_start_) & 0xfff) == 0);
-  int initial_length =
-      static_cast<int>(base::OS::CommitPageSize() / kPointerSize);
-  DCHECK(initial_length > 0);
-  DCHECK(initial_length <= kOldStoreBufferLength);
+  CHECK((reinterpret_cast<uintptr_t>(old_start_) & 0xfff) == 0);
+  CHECK(kStoreBufferSize >= base::OS::CommitPageSize());
+  // Initial size of the old buffer is as big as the buffer for new pointers.
+  // This means even if we later fail to enlarge the old buffer due to OOM from
+  // the OS, we will still be able to empty the new pointer buffer into the old
+  // buffer.
+  int initial_length = static_cast<int>(kStoreBufferSize / kPointerSize);
+  CHECK(initial_length > 0);
+  CHECK(initial_length <= kOldStoreBufferLength);
   old_limit_ = old_start_ + initial_length;
   old_reserved_limit_ = old_start_ + kOldStoreBufferLength;
 
   if (!old_virtual_memory_->Commit(reinterpret_cast<void*>(old_start_),
                                    (old_limit_ - old_start_) * kPointerSize,
                                    false)) {
     V8::FatalProcessOutOfMemory("StoreBuffer::SetUp");
   }
 
   DCHECK(reinterpret_cast<Address>(start_) >= virtual_memory_->address());
@@ skipping 45 matching lines @@
 
 bool StoreBuffer::SpaceAvailable(intptr_t space_needed) {
   return old_limit_ - old_top_ >= space_needed;
 }
 
 
 void StoreBuffer::EnsureSpace(intptr_t space_needed) {
   while (old_limit_ - old_top_ < space_needed &&
          old_limit_ < old_reserved_limit_) {
     size_t grow = old_limit_ - old_start_;  // Double size.
-    if (!old_virtual_memory_->Commit(reinterpret_cast<void*>(old_limit_),
-                                     grow * kPointerSize, false)) {
-      V8::FatalProcessOutOfMemory("StoreBuffer::EnsureSpace");
+    if (old_virtual_memory_->Commit(reinterpret_cast<void*>(old_limit_),
+                                    grow * kPointerSize, false)) {
+      old_limit_ += grow;
+    } else {
+      break;
     }
-    old_limit_ += grow;
   }
 
   if (SpaceAvailable(space_needed)) return;
 
   if (old_buffer_is_filtered_) return;
   DCHECK(may_move_store_buffer_entries_);
   Compact();
 
   old_buffer_is_filtered_ = true;
   bool page_has_scan_on_scavenge_flag = false;
@@ skipping 432 matching lines @@
     }
     old_buffer_is_sorted_ = false;
     old_buffer_is_filtered_ = false;
     *old_top_++ = reinterpret_cast<Address>(int_addr << kPointerSizeLog2);
     DCHECK(old_top_ <= old_limit_);
   }
   heap_->isolate()->counters()->store_buffer_compactions()->Increment();
 }
 }
 }  // namespace v8::internal