Add last OS error into heap stats.

That could allow us to understand why commit of from space sometimes fails.
Another option would be start a separate structure with OS-related info, but
as it's a single field, let's put it into HeapStats, at least for now.

Review URL: http://codereview.chromium.org/3118013

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5261 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/api.cc

@@ -174,6 +174,8 @@ void i::V8::FatalProcessOutOfMemory(const char* location, bool take_snapshot) {
   heap_stats.objects_per_type = objects_per_type;
   int size_per_type[LAST_TYPE + 1] = {0};
   heap_stats.size_per_type = size_per_type;
+  int os_error;
+  heap_stats.os_error = &os_error;
   int end_marker;
   heap_stats.end_marker = &end_marker;
   i::Heap::RecordStats(&heap_stats, take_snapshot);

src/heap.cc

@@ -4076,6 +4076,7 @@ void Heap::RecordStats(HeapStats* stats, bool take_snapshot) {
   *stats->memory_allocator_size = MemoryAllocator::Size();
   *stats->memory_allocator_capacity =
       MemoryAllocator::Size() + MemoryAllocator::Available();
+  *stats->os_error = OS::GetLastError();
   if (take_snapshot) {
     HeapIterator iterator;
     for (HeapObject* obj = iterator.next();

src/heap.h

@@ -1345,7 +1345,8 @@ class HeapStats {
   int* memory_allocator_capacity;       // 20
   int* objects_per_type;                // 21
   int* size_per_type;                   // 22
-  int* end_marker;                      // 23
+  int* os_error;                        // 23
+  int* end_marker;                      // 24
 };
 
 

src/platform-nullos.cc

@@ -100,6 +100,12 @@ double OS::DaylightSavingsOffset(double time) {
 }
 
 
+int OS::GetLastError() {
+  UNIMPLEMENTED();
+  return 0;
+}
+
+
 // Returns the local time offset in milliseconds east of UTC without
 // taking daylight savings time into account.
 double OS::LocalTimeOffset() {

src/platform-posix.cc

@@ -108,6 +108,11 @@ double OS::DaylightSavingsOffset(double time) {
 }
 
 
+int OS::GetLastError() {
+  return errno;
+}
+
+
 // ----------------------------------------------------------------------------
 // POSIX stdio support.
 //

src/platform-win32.cc

@@ -651,6 +651,11 @@ double OS::DaylightSavingsOffset(double time) {
 }
 
 
+int OS::GetLastError() {
+  return ::GetLastError();
+}
+
+
 // ----------------------------------------------------------------------------
 // Win32 console output.
 //

src/platform.h

@@ -165,6 +165,9 @@ class OS {
   // Returns the daylight savings offset for the given time.
   static double DaylightSavingsOffset(double time);
 
+  // Returns last OS error.
+  static int GetLastError();
+
   static FILE* FOpen(const char* path, const char* mode);
 
   // Log file open mode is platform-dependent due to line ends issues.