Moved isolate high watermark calculations into the Observatory client.

BUG=
R=johnmccutchan@google.com

Review-Url: https://codereview.chromium.org/2656723002 .

runtime/observatory/lib/src/service/object.dart

@@ -1508,7 +1508,7 @@ class Isolate extends ServiceObjectOwner implements M.Isolate {
   final List<Thread> _threads = new List<Thread>();
 
   int get memoryHighWatermark => _memoryHighWatermark;
-  int _memoryHighWatermark;
+  int _memoryHighWatermark = 0;
 
   int get numZoneHandles => _numZoneHandles;
   int _numZoneHandles;
@@ -1645,10 +1645,13 @@ class Isolate extends ServiceObjectOwner implements M.Isolate {
       threads.addAll(map['_threads']);
     }
 
-    _memoryHighWatermark = int.parse(map['_memoryHighWatermark']);
+    int currentMemoryHighWatermark = 0;
+    for (var i = 0; i < threads.length; i++) {
+      currentMemoryHighWatermark += threads[i].memoryHighWatermark;
+    }
 
-    if (map['threads'] != null) {
-      threads.addAll(map['threads']);
+    if (currentMemoryHighWatermark > _memoryHighWatermark) {
+      _memoryHighWatermark = currentMemoryHighWatermark;
     }
 
     _numZoneHandles = map['_numZoneHandles'];

runtime/vm/isolate.cc

@@ -783,7 +783,6 @@ Isolate::Isolate(const Dart_IsolateFlags& api_flags)
       single_step_(false),
       thread_registry_(new ThreadRegistry()),
       safepoint_handler_(new SafepointHandler(this)),
-      memory_high_watermark_(0),
       message_notify_callback_(NULL),
       name_(NULL),
       debugger_name_(NULL),
@@ -2118,7 +2117,6 @@ void Isolate::PrintJSON(JSONStream* stream, bool ref) {
     }
   }
 
-  jsobj.AddPropertyF("_memoryHighWatermark", "%" Pu "", memory_high_watermark_);
   jsobj.AddProperty("_threads", thread_registry_);
 }
 #endif
@@ -2717,7 +2715,6 @@ void Isolate::UnscheduleThread(Thread* thread,
     // Ensure that the thread reports itself as being at a safepoint.
     thread->EnterSafepoint();
   }
-  UpdateMemoryHighWatermark();
   OSThread* os_thread = thread->os_thread();
   ASSERT(os_thread != NULL);
   os_thread->DisableThreadInterrupts();
@@ -2738,15 +2735,6 @@ void Isolate::UnscheduleThread(Thread* thread,
 }
 
 
-void Isolate::UpdateMemoryHighWatermark() {
-  const uintptr_t thread_watermarks_total =
-      thread_registry()->ThreadHighWatermarksTotalLocked();
-  if (thread_watermarks_total > memory_high_watermark_) {
-    memory_high_watermark_ = thread_watermarks_total;
-  }
-}
-
-
 static RawInstance* DeserializeObject(Thread* thread,
                                       uint8_t* obj_data,
                                       intptr_t obj_len) {

runtime/vm/isolate.h

@@ -179,7 +179,6 @@ class Isolate : public BaseIsolate {
 
   ThreadRegistry* thread_registry() const { return thread_registry_; }
   SafepointHandler* safepoint_handler() const { return safepoint_handler_; }
-  uintptr_t memory_high_watermark() const { return memory_high_watermark_; }
   ClassTable* class_table() { return &class_table_; }
   static intptr_t class_table_offset() {
     return OFFSET_OF(Isolate, class_table_);
@@ -692,10 +691,6 @@ class Isolate : public BaseIsolate {
                         bool is_mutator,
                         bool bypass_safepoint = false);
 
-  // Updates the maximum memory usage in bytes of all zones in all threads of
-  // the current isolate.
-  void UpdateMemoryHighWatermark();
-
   // DEPRECATED: Use Thread's methods instead. During migration, these default
   // to using the mutator thread (which must also be the current thread).
   Zone* current_zone() const {
@@ -716,7 +711,6 @@ class Isolate : public BaseIsolate {
 
   ThreadRegistry* thread_registry_;
   SafepointHandler* safepoint_handler_;
-  uintptr_t memory_high_watermark_;
   Dart_MessageNotifyCallback message_notify_callback_;
   char* name_;
   char* debugger_name_;

runtime/vm/thread_registry.cc

@@ -195,16 +195,4 @@ void ThreadRegistry::ReturnToFreelistLocked(Thread* thread) {
   free_list_ = thread;
 }
 
-
-uintptr_t ThreadRegistry::ThreadHighWatermarksTotalLocked() const {
-  ASSERT(threads_lock()->IsOwnedByCurrentThread());
-  uintptr_t memory_high_watermarks_total = 0;
-  Thread* current = active_list_;
-  while (current != NULL) {
-    memory_high_watermarks_total += current->memory_high_watermark();
-    current = current->next_;
-  }
-  return memory_high_watermarks_total;
-}
-
 }  // namespace dart

runtime/vm/thread_test.cc

@@ -321,14 +321,6 @@ TEST_CASE(ManySimpleTasksWithZones) {
   const char* json = stream.ToCString();
 
   Thread* current_thread = Thread::Current();
-  {
-    StackZone stack_zone(current_thread);
-    char* isolate_info_buf = OS::SCreate(current_thread->zone(),
-                                         "\"_memoryHighWatermark\":"
-                                         "\"%" Pu "\"",
-                                         isolate->memory_high_watermark());
-    EXPECT_SUBSTRING(isolate_info_buf, json);
-  }
 
   // Confirm all expected entries are in the JSON output.
   for (intptr_t i = 0; i < kTaskCount + 1; i++) {