Created methods to surface zone memory information for each isolate and thread in JSON.

runtime/vm/zone_test.cc

Index: runtime/vm/zone_test.cc
diff --git a/runtime/vm/zone_test.cc b/runtime/vm/zone_test.cc
index 4cb9231c74d539bd6486eff29c5adafbd536c833..a952d5f0dbd1bdc183e8cdde525087e37c558c6b 100644
--- a/runtime/vm/zone_test.cc
+++ b/runtime/vm/zone_test.cc
@@ -169,4 +169,70 @@ TEST_CASE(PrintToString) {
   EXPECT_STREQ("Hello World!", result);
 }
 
+#ifndef RELEASE
+UNIT_TEST_CASE(PrintZoneMemoryInfoToJSON) {
+#if defined(DEBUG)
+  FLAG_trace_zones = true;
+#endif
+  Dart_CreateIsolate(NULL, NULL, bin::isolate_snapshot_buffer, NULL, NULL,
+                     NULL);
+  Thread* thread = Thread::Current();
+  EXPECT(thread->zone() == NULL);
+  {
+    StackZone zone(thread);
+    EXPECT(thread->zone() != NULL);
+
+    intptr_t allocated_size = 0;
+    const intptr_t kNumElements = 1000;
+
+    zone.GetZone()->Alloc<uint32_t>(kNumElements);
+    allocated_size += sizeof(uint32_t) * kNumElements;
+
+    EXPECT_LE(allocated_size, zone.SizeInBytes());
+    {
+      JSONStream stream;
+      {
+        JSONObject obj(&stream);
+        // Get the JSON formated zone information.
+        zone.GetZone()->PrintToJSONObject(&obj);
+      }
+      const char* json = stream.ToCString();
+      char address_buf[64];
+      char size_buf[64];
+
+      // Ensure that address and size matches actual values.
+      snprintf(address_buf, sizeof(address_buf), "\"address\":\"0x%" Px "\"",
+               reinterpret_cast<uword>(zone.GetZone()));
+      snprintf(size_buf, sizeof(size_buf), "\"size\":%ld", zone.SizeInBytes());

[siva, 2016/12/07 22:12:53]

Ditto comment about using OS::SNPrint instead of snprintf

+
+      EXPECT_SUBSTRING(address_buf, json);
+      EXPECT_SUBSTRING(size_buf, json);
+    }
+
+    // Expand the zone to ensure that JSON is updated accordingly.
+    zone.GetZone()->Alloc<uint32_t>(kNumElements);
+    allocated_size += sizeof(uint32_t) * kNumElements;
+    EXPECT_LE(allocated_size, zone.SizeInBytes());
+    {
+      JSONStream stream;
+      {
+        JSONObject obj(&stream);
+        zone.GetZone()->PrintToJSONObject(&obj);
+      }
+      const char* json = stream.ToCString();
+      char address_buf[64];
+      char size_buf[64];
+
+      snprintf(address_buf, sizeof(address_buf), "\"address\":\"0x%" Px "\"",
+               reinterpret_cast<uword>(zone.GetZone()));
+      snprintf(size_buf, sizeof(size_buf), "\"size\":%ld", zone.SizeInBytes());
+
+      EXPECT_SUBSTRING(address_buf, json);
+      EXPECT_SUBSTRING(size_buf, json);
+    }
+  }
+  EXPECT(thread->zone() == NULL);
+  Dart_ShutdownIsolate();
+}
+#endif
 }  // namespace dart