Revert "[vm, service] Gather used and capacity from various mallocs."

This reverts commit 84f9eee.

Reason for revert: Weak linking does not work on iOS

Original change's description:
> [vm, service] Gather used and capacity from various mallocs.
> 
> Change-Id: I9d397b3b865a804252d1adc90c03a369bf88aff3
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/159186
> Commit-Queue: Ryan Macnak <rmacnak@google.com>
> Reviewed-by: Ben Konyi <bkonyi@google.com>

TBR=bkonyi@google.com,rmacnak@google.com

Change-Id: I6c9e17783ee5a3296296677cad11d036aa8fa060
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/160401
Reviewed-by: Ryan Macnak <rmacnak@google.com>

runtime/observatory/lib/src/elements/vm_view.dart

@@ -174,39 +174,27 @@ class VMViewElement extends CustomElement implements Renderable {
               ..children = <Element>[
                 new DivElement()
                   ..classes = ['memberName']
-                  ..text = 'malloc used memory',
+                  ..text = 'malloc memory',
                 new DivElement()
                   ..classes = ['memberValue']
-                  ..text = _vm.mallocUsed != null
-                      ? Utils.formatSize(_vm.mallocUsed)
+                  ..text = _vm.heapAllocatedMemoryUsage != null
+                      ? Utils.formatSize(_vm.heapAllocatedMemoryUsage)
                       : 'unavailable'
-                  ..title =
-                      _vm.mallocUsed != null ? '${_vm.mallocUsed} bytes' : null
-              ],
-            new DivElement()
-              ..classes = ['memberItem']
-              ..children = <Element>[
-                new DivElement()
-                  ..classes = ['memberName']
-                  ..text = 'malloc capacity memory',
-                new DivElement()
-                  ..classes = ['memberValue']
-                  ..text = _vm.mallocCapacity != null
-                      ? Utils.formatSize(_vm.mallocCapacity)
-                      : 'unavailable'
-                  ..title = _vm.mallocCapacity != null
-                      ? '${_vm.mallocCapacity} bytes'
+                  ..title = _vm.heapAllocatedMemoryUsage != null
+                      ? '${_vm.heapAllocatedMemoryUsage} bytes'
                       : null
               ],
             new DivElement()
               ..classes = ['memberItem']
               ..children = <Element>[
                 new DivElement()
                   ..classes = ['memberName']
-                  ..text = 'malloc implementation',
+                  ..text = 'malloc allocation count',
                 new DivElement()
                   ..classes = ['memberValue']
-                  ..text = _vm.mallocImplementation
+                  ..text = _vm.heapAllocationCount != null
+                      ? '${_vm.heapAllocationCount}'
+                      : 'unavailable'
               ],
             new DivElement()
               ..classes = ['memberItem']

runtime/observatory/lib/src/models/objects/vm.dart

@@ -35,9 +35,10 @@ abstract class VM implements VMRef {
   int get pid;
 
   /// The current amount of native heap allocated memory within the VM.
-  int get mallocUsed;
-  int get mallocCapacity;
-  String get mallocImplementation;
+  int get heapAllocatedMemoryUsage;
+
+  /// The current number of allocations on the native heap within the VM.
+  int get heapAllocationCount;
 
   int get currentMemory;
   int get maxRSS;

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

@@ -684,9 +684,8 @@ abstract class VM extends ServiceObjectOwner implements M.VM {
   bool typeChecksEnabled = false;
   int nativeZoneMemoryUsage = 0;
   int pid = 0;
-  int mallocUsed = 0;
-  int mallocCapacity = 0;
-  String mallocImplementation = 'unknown';
+  int heapAllocatedMemoryUsage = 0;
+  int heapAllocationCount = 0;
   int currentMemory;
   int maxRSS;
   int currentRSS;
@@ -1048,9 +1047,8 @@ abstract class VM extends ServiceObjectOwner implements M.VM {
       nativeZoneMemoryUsage = map['_nativeZoneMemoryUsage'];
     }
     pid = map['pid'];
-    mallocUsed = map['_mallocUsed'];
-    mallocCapacity = map['_mallocCapacity'];
-    mallocImplementation = map['_mallocImplementation'];
+    heapAllocatedMemoryUsage = map['_heapAllocatedMemoryUsage'];
+    heapAllocationCount = map['_heapAllocationCount'];
     embedder = map['_embedder'];
     currentMemory = map['_currentMemory'];
     maxRSS = map['_maxRSS'];

runtime/vm/malloc_hooks.h

@@ -30,9 +30,7 @@ class MallocHooks : public AllStatic {
   static void set_stack_trace_collection_enabled(bool enabled);
   static void ResetStats();
   static bool Active();
-  static bool GetStats(intptr_t* used,
-                       intptr_t* capacity,
-                       const char** implementation);
+  static void PrintToJSONObject(JSONObject* jsobj);
   static Sample* GetSample(const void* ptr);
 
   static intptr_t allocation_count();

runtime/vm/malloc_hooks_tcmalloc.cc

@@ -10,8 +10,6 @@
 
 #include "gperftools/malloc_hook.h"
 
-#include <malloc.h>
-
 #include "platform/assert.h"
 #include "vm/hash_map.h"
 #include "vm/json_stream.h"
@@ -336,14 +334,29 @@ bool MallocHooks::Active() {
   return MallocHooksState::Active();
 }
 
-bool MallocHooks::GetStats(intptr_t* used,
-                           intptr_t* capacity,
-                           const char** implementation) {
-  struct mallinfo info = mallinfo();
-  *used = info.uordblks;
-  *capacity = *used + info.fordblks;
-  *implementation = "tcmalloc";
-  return true;
+void MallocHooks::PrintToJSONObject(JSONObject* jsobj) {
+  if (!FLAG_profiler_native_memory) {
+    return;
+  }
+  intptr_t allocated_memory = 0;
+  intptr_t allocation_count = 0;
+  bool add_usage = false;
+  // AddProperty may call malloc which would result in an attempt
+  // to acquire the lock recursively so we extract the values first
+  // and then add the JSON properties.
+  {
+    MallocLocker ml(MallocHooksState::malloc_hook_mutex(),
+                    MallocHooksState::malloc_hook_mutex_owner());
+    if (MallocHooksState::Active()) {
+      allocated_memory = MallocHooksState::heap_allocated_memory_in_bytes();
+      allocation_count = MallocHooksState::allocation_count();
+      add_usage = true;
+    }
+  }
+  if (add_usage) {
+    jsobj->AddProperty("_heapAllocatedMemoryUsage", allocated_memory);
+    jsobj->AddProperty("_heapAllocationCount", allocation_count);
+  }
 }
 
 intptr_t MallocHooks::allocation_count() {

runtime/vm/malloc_hooks_unsupported.cc

@@ -8,24 +8,6 @@
 
 #include "vm/malloc_hooks.h"
 
-#include "vm/json_stream.h"
-
-#if defined(HOST_OS_LINUX) || defined(HOST_OS_ANDROID)
-#include <malloc.h>
-#elif defined(HOST_OS_MACOS)
-#include <malloc/malloc.h>
-#endif
-
-#if !defined(HOST_OS_WINDOWS)
-extern "C" {
-__attribute__((weak)) uintptr_t __sanitizer_get_current_allocated_bytes();
-__attribute__((weak)) uintptr_t __sanitizer_get_heap_size();
-__attribute__((weak)) int __sanitizer_install_malloc_and_free_hooks(
-    void (*malloc_hook)(const void*, uintptr_t),
-    void (*free_hook)(const void*));
-}
-#endif
-
 namespace dart {
 
 void MallocHooks::Init() {
@@ -56,37 +38,8 @@ bool MallocHooks::Active() {
   return false;
 }
 
-bool MallocHooks::GetStats(intptr_t* used,
-                           intptr_t* capacity,
-                           const char** implementation) {
-#if !defined(PRODUCT)
-#if !defined(HOST_OS_WINDOWS)
-  if (__sanitizer_get_current_allocated_bytes != nullptr &&
-      __sanitizer_get_heap_size != nullptr) {
-    *used = __sanitizer_get_current_allocated_bytes();
-    *capacity = __sanitizer_get_heap_size();
-    *implementation = "scudo";
-    return true;
-  }
-#endif
-#if defined(HOST_OS_LINUX) || defined(HOST_OS_ANDROID)
-  struct mallinfo info = mallinfo();
-  *used = info.uordblks;
-  *capacity = *used + info.fordblks;
-  *implementation = "unknown";
-  return true;
-#elif defined(HOST_OS_MACOS)
-  struct mstats stats = mstats();
-  *used = stats.bytes_used;
-  *capacity = stats.bytes_total;
-  *implementation = "macos";
-  return true;
-#else
-  return false;
-#endif
-#else
-  return false;
-#endif
+void MallocHooks::PrintToJSONObject(JSONObject* jsobj) {
+  // Do nothing.
 }
 
 Sample* MallocHooks::GetSample(const void* ptr) {