Factor out a Histogram class from HistogramTimer, and use it to measure external fragmentation

src/v8-counters.h

Index: src/v8-counters.h
diff --git a/src/v8-counters.h b/src/v8-counters.h
index dc55042b462ee08a86d7685ea4176fe050c3fb6d..c7de7d9cbb3c1f2613629e285b74bcf15006afcd 100644
--- a/src/v8-counters.h
+++ b/src/v8-counters.h
@@ -50,6 +50,32 @@ namespace internal {
   HT(compile_lazy, V8.CompileLazy)
 
 
+#define HISTOGRAM_MEMORY_LIST(HM)                                     \
+  HM(new_space_bytes_available, V8.MemoryNewSpaceBytesAvailable)      \
+  HM(new_space_bytes_committed, V8.MemoryNewSpaceBytesCommitted)      \
+  HM(new_space_bytes_used, V8.MemoryNewSpaceBytesUsed)                \
+  HM(old_pointer_space_bytes_available,                               \
+     V8.MemoryOldPointerSpaceBytesAvailable)                          \
+  HM(old_pointer_space_bytes_committed,                               \
+     V8.MemoryOldPointerSpaceBytesCommitted)                          \
+  HM(old_pointer_space_bytes_used, V8.MemoryOldPointerSpaceBytesUsed) \
+  HM(old_data_space_bytes_available, V8.MemoryOldDataSpaceBytesAvailable) \
+  HM(old_data_space_bytes_committed, V8.MemoryOldDataSpaceBytesCommitted) \
+  HM(old_data_space_bytes_used, V8.MemoryOldDataSpaceBytesUsed)       \
+  HM(code_space_bytes_available, V8.MemoryCodeSpaceBytesAvailable)    \
+  HM(code_space_bytes_committed, V8.MemoryCodeSpaceBytesCommitted)    \
+  HM(code_space_bytes_used, V8.MemoryCodeSpaceBytesUsed)              \
+  HM(map_space_bytes_available, V8.MemoryMapSpaceBytesAvailable)      \
+  HM(map_space_bytes_committed, V8.MemoryMapSpaceBytesCommitted)      \
+  HM(map_space_bytes_used, V8.MemoryMapSpaceBytesUsed)                \
+  HM(cell_space_bytes_available, V8.MemoryCellSpaceBytesAvailable)    \
+  HM(cell_space_bytes_committed, V8.MemoryCellSpaceBytesCommitted)    \
+  HM(cell_space_bytes_used, V8.MemoryCellSpaceBytesUsed)              \
+  HM(lo_space_bytes_available, V8.MemoryLoSpaceBytesAvailable)        \
+  HM(lo_space_bytes_committed, V8.MemoryLoSpaceBytesCommitted)        \
+  HM(lo_space_bytes_used, V8.MemoryLoSpaceBytesUsed)
+
+
 // WARNING: STATS_COUNTER_LIST_* is a very large macro that is causing MSVC
 // Intellisense to crash.  It was broken into two macros (each of length 40
 // lines) rather than one macro (of length about 80 lines) to work around
@@ -246,30 +272,7 @@ namespace internal {
   SC(smi_checks_removed, V8.SmiChecksRemoved)                         \
   SC(map_checks_removed, V8.MapChecksRemoved)                         \
   SC(quote_json_char_count, V8.QuoteJsonCharacterCount)               \
-  SC(quote_json_char_recount, V8.QuoteJsonCharacterReCount)           \
-  SC(new_space_bytes_available, V8.MemoryNewSpaceBytesAvailable)      \
-  SC(new_space_bytes_committed, V8.MemoryNewSpaceBytesCommitted)      \
-  SC(new_space_bytes_used, V8.MemoryNewSpaceBytesUsed)                \
-  SC(old_pointer_space_bytes_available,                               \
-     V8.MemoryOldPointerSpaceBytesAvailable)                          \
-  SC(old_pointer_space_bytes_committed,                               \
-     V8.MemoryOldPointerSpaceBytesCommitted)                          \
-  SC(old_pointer_space_bytes_used, V8.MemoryOldPointerSpaceBytesUsed) \
-  SC(old_data_space_bytes_available, V8.MemoryOldDataSpaceBytesAvailable) \
-  SC(old_data_space_bytes_committed, V8.MemoryOldDataSpaceBytesCommitted) \
-  SC(old_data_space_bytes_used, V8.MemoryOldDataSpaceBytesUsed)       \
-  SC(code_space_bytes_available, V8.MemoryCodeSpaceBytesAvailable)    \
-  SC(code_space_bytes_committed, V8.MemoryCodeSpaceBytesCommitted)    \
-  SC(code_space_bytes_used, V8.MemoryCodeSpaceBytesUsed)              \
-  SC(map_space_bytes_available, V8.MemoryMapSpaceBytesAvailable)      \
-  SC(map_space_bytes_committed, V8.MemoryMapSpaceBytesCommitted)      \
-  SC(map_space_bytes_used, V8.MemoryMapSpaceBytesUsed)                \
-  SC(cell_space_bytes_available, V8.MemoryCellSpaceBytesAvailable)    \
-  SC(cell_space_bytes_committed, V8.MemoryCellSpaceBytesCommitted)    \
-  SC(cell_space_bytes_used, V8.MemoryCellSpaceBytesUsed)              \
-  SC(lo_space_bytes_available, V8.MemoryLoSpaceBytesAvailable)        \
-  SC(lo_space_bytes_committed, V8.MemoryLoSpaceBytesCommitted)        \
-  SC(lo_space_bytes_used, V8.MemoryLoSpaceBytesUsed)
+  SC(quote_json_char_recount, V8.QuoteJsonCharacterReCount)
 
 
 // This file contains all the v8 counters that are in use.
@@ -280,6 +283,11 @@ class Counters {
   HISTOGRAM_TIMER_LIST(HT)
 #undef HT
 
+#define HM(name, caption) \
+  Histogram* name() { return &name##_; }
+  HISTOGRAM_MEMORY_LIST(HM)
+#undef HM
+
 #define SC(name, caption) \
   StatsCounter* name() { return &name##_; }
   STATS_COUNTER_LIST_1(SC)
@@ -290,6 +298,9 @@ class Counters {
 #define RATE_ID(name, caption) k_##name,
     HISTOGRAM_TIMER_LIST(RATE_ID)
 #undef RATE_ID
+#define MEMORY_ID(name, caption) k_##name,
+    HISTOGRAM_MEMORY_LIST(MEMORY_ID)
+#undef MEMORY_ID
 #define COUNTER_ID(name, caption) k_##name,
     STATS_COUNTER_LIST_1(COUNTER_ID)
     STATS_COUNTER_LIST_2(COUNTER_ID)
@@ -310,6 +321,11 @@ class Counters {
   HISTOGRAM_TIMER_LIST(HT)
 #undef HT
 
+#define HM(name, caption) \
+  Histogram name##_;
+  HISTOGRAM_MEMORY_LIST(HM)
+#undef HM
+
 #define SC(name, caption) \
   StatsCounter name##_;
   STATS_COUNTER_LIST_1(SC)