[vm] Don't enable the profiler by default. Enable the profiler at startup with --observe, or later …

runtime/vm/malloc_hooks_test.cc

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 
 #if defined(DART_USE_TCMALLOC) && !defined(PRODUCT) && !defined(TARGET_ARCH_DBC)
 
 #include "platform/assert.h"
 #include "vm/globals.h"
 #include "vm/malloc_hooks.h"
 #include "vm/os.h"
 #include "vm/profiler.h"
 #include "vm/profiler_service.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
 static void MallocHookTestBufferInitializer(volatile char* buffer,
                                             uintptr_t size) {
   // Run through the buffer and do something. If we don't do this and the memory
   // in buffer isn't touched, the tcmalloc hooks won't be called.
   for (uintptr_t i = 0; i < size; ++i) {
     buffer[i] = i;
   }
 }
 
+class EnableMallocHooksScope : public ValueObject {
+ public:
+  EnableMallocHooksScope() {
+    saved_enable_malloc_hooks_ = FLAG_profiler_native_memory;
+    FLAG_profiler_native_memory = true;
+    Profiler::InitAllocationSampleBuffer();
+    MallocHooks::InitOnce();
+    MallocHooks::ResetStats();
+  }
+
+  ~EnableMallocHooksScope() {
+    MallocHooks::TearDown();
+    FLAG_profiler_native_memory = saved_enable_malloc_hooks_;
+  }
+
+ private:
+  bool saved_enable_malloc_hooks_;
+};
+
+class EnableMallocHooksAndStacksScope : public EnableMallocHooksScope {
+ public:
+  EnableMallocHooksAndStacksScope() {
+    saved_enable_stack_traces_ = MallocHooks::stack_trace_collection_enabled();
+    MallocHooks::set_stack_trace_collection_enabled(true);
+    if (!FLAG_profiler) {
+      FLAG_profiler = true;
+      Profiler::InitOnce();
+    }
+  }
+
+  ~EnableMallocHooksAndStacksScope() {
+    MallocHooks::set_stack_trace_collection_enabled(saved_enable_stack_traces_);
+  }
+
+ private:
+  bool saved_enable_stack_traces_;
+};
+
 UNIT_TEST_CASE(BasicMallocHookTest) {
-  bool enable_malloc_hooks_saved = FLAG_profiler_native_memory;
-  FLAG_profiler_native_memory = true;
-  Profiler::InitAllocationSampleBuffer();
+  EnableMallocHooksScope scope;
 
-  MallocHooks::InitOnce();
-  MallocHooks::ResetStats();
   EXPECT_EQ(0L, MallocHooks::allocation_count());
   EXPECT_EQ(0L, MallocHooks::heap_allocated_memory_in_bytes());
   const intptr_t buffer_size = 10;
   char* buffer = new char[buffer_size];
   MallocHookTestBufferInitializer(buffer, buffer_size);
 
   EXPECT_EQ(1L, MallocHooks::allocation_count());
   EXPECT_EQ(static_cast<intptr_t>(sizeof(char) * buffer_size),
             MallocHooks::heap_allocated_memory_in_bytes());
 
   delete[] buffer;
   EXPECT_EQ(0L, MallocHooks::allocation_count());
   EXPECT_EQ(0L, MallocHooks::heap_allocated_memory_in_bytes());
-  MallocHooks::TearDown();
-
-  FLAG_profiler_native_memory = enable_malloc_hooks_saved;
 }
 
 UNIT_TEST_CASE(FreeUnseenMemoryMallocHookTest) {
-  bool enable_malloc_hooks_saved = FLAG_profiler_native_memory;
-  FLAG_profiler_native_memory = true;
-  Profiler::InitAllocationSampleBuffer();
+  EnableMallocHooksScope scope;
 
-  MallocHooks::InitOnce();
   const intptr_t pre_hook_buffer_size = 3;
   char* pre_hook_buffer = new char[pre_hook_buffer_size];
   MallocHookTestBufferInitializer(pre_hook_buffer, pre_hook_buffer_size);
 
   MallocHooks::ResetStats();
   EXPECT_EQ(0L, MallocHooks::allocation_count());
   EXPECT_EQ(0L, MallocHooks::heap_allocated_memory_in_bytes());
 
   const intptr_t buffer_size = 10;
   char* buffer = new char[buffer_size];
   MallocHookTestBufferInitializer(buffer, buffer_size);
 
   EXPECT_EQ(1L, MallocHooks::allocation_count());
   EXPECT_EQ(static_cast<intptr_t>(sizeof(char) * buffer_size),
             MallocHooks::heap_allocated_memory_in_bytes());
 
   delete[] pre_hook_buffer;
   EXPECT_EQ(1L, MallocHooks::allocation_count());
   EXPECT_EQ(static_cast<intptr_t>(sizeof(char) * buffer_size),
             MallocHooks::heap_allocated_memory_in_bytes());
 
   delete[] buffer;
   EXPECT_EQ(0L, MallocHooks::allocation_count());
   EXPECT_EQ(0L, MallocHooks::heap_allocated_memory_in_bytes());
-  MallocHooks::TearDown();
-
-  FLAG_profiler_native_memory = enable_malloc_hooks_saved;
 }
 
 VM_UNIT_TEST_CASE(StackTraceMallocHookSimpleTest) {
-  bool enable_malloc_hooks_saved = FLAG_profiler_native_memory;
-  FLAG_profiler_native_memory = true;
-  Profiler::InitAllocationSampleBuffer();
-
-  MallocHooks::InitOnce();
-  MallocHooks::ResetStats();
-
-  bool enable_stack_traces_saved =
-      MallocHooks::stack_trace_collection_enabled();
-  MallocHooks::set_stack_trace_collection_enabled(true);
+  EnableMallocHooksAndStacksScope scope;
 
   char* var = static_cast<char*>(malloc(16 * sizeof(char)));
   Sample* sample = MallocHooks::GetSample(var);
   EXPECT(sample != NULL);
 
   free(var);
   sample = MallocHooks::GetSample(var);
   EXPECT(sample == NULL);
-  MallocHooks::TearDown();
-  MallocHooks::set_stack_trace_collection_enabled(enable_stack_traces_saved);
-  FLAG_profiler_native_memory = enable_malloc_hooks_saved;
 }
 
 static char* DART_NOINLINE StackTraceLengthHelper(uintptr_t* end_address) {
   char* var = static_cast<char*>(malloc(16 * sizeof(char)));
   *end_address = OS::GetProgramCounter();
   return var;
 }
 
 VM_UNIT_TEST_CASE(StackTraceMallocHookLengthTest) {
-  bool enable_malloc_hooks_saved = FLAG_profiler_native_memory;
-  FLAG_profiler_native_memory = true;
-  Profiler::InitAllocationSampleBuffer();
+  EnableMallocHooksAndStacksScope scope;
 
   uintptr_t test_start_address =
       reinterpret_cast<uintptr_t>(Dart_TestStackTraceMallocHookLengthTest);
   uintptr_t helper_start_address =
       reinterpret_cast<uintptr_t>(StackTraceLengthHelper);
   uintptr_t helper_end_address = 0;
 
-  MallocHooks::InitOnce();
-  MallocHooks::ResetStats();
-
-  bool enable_stack_traces_saved =
-      MallocHooks::stack_trace_collection_enabled();
-  MallocHooks::set_stack_trace_collection_enabled(true);
-
   char* var = StackTraceLengthHelper(&helper_end_address);
   Sample* sample = MallocHooks::GetSample(var);
   EXPECT(sample != NULL);
   uintptr_t test_end_address = OS::GetProgramCounter();
 
   // Ensure that all stack frames are where we expect them to be in the sample.
   // If they aren't, the kSkipCount constant in malloc_hooks.cc is likely
   // incorrect.
   uword address = sample->At(0);
   bool first_result =
@@ skipping 11 matching lines @@
         "incorrect for this configuration/platform. This value can be"
         " found in malloc_hooks.cc in the AllocationInfo class, and "
         "is stored in the kSkipCount constant.\n");
     OS::PrintErr("First result: %d Second Result: %d\n", first_result,
                  second_result);
     OS::PrintErr("Dumping sample stack trace:\n");
     sample->DumpStackTrace();
   }
 
   free(var);
-  MallocHooks::TearDown();
-  MallocHooks::set_stack_trace_collection_enabled(enable_stack_traces_saved);
-  FLAG_profiler_native_memory = enable_malloc_hooks_saved;
 }
 
 ISOLATE_UNIT_TEST_CASE(StackTraceMallocHookSimpleJSONTest) {
-  bool enable_malloc_hooks_saved = FLAG_profiler_native_memory;
-  FLAG_profiler_native_memory = true;
-  Profiler::InitAllocationSampleBuffer();
-
-  MallocHooks::InitOnce();
-  MallocHooks::ResetStats();
-
-  bool enable_stack_traces_saved =
-      MallocHooks::stack_trace_collection_enabled();
-  MallocHooks::set_stack_trace_collection_enabled(true);
+  EnableMallocHooksAndStacksScope scope;
 
   ClearProfileVisitor cpv(Isolate::Current());
   Profiler::sample_buffer()->VisitSamples(&cpv);
 
   char* var = static_cast<char*>(malloc(16 * sizeof(char)));
   JSONStream js;
   ProfilerService::PrintNativeAllocationJSON(&js, Profile::kNoTags, -1, -1);
   const char* json = js.ToCString();
 
   // Check that all the stack frames from the current down to main are actually
   // present in the profile. This is just a simple sanity check to make sure
   // that the ProfileTrie has a representation of the stack trace collected when
   // var is allocated. More intense testing is already done in profiler_test.cc.
   EXPECT_SUBSTRING("\"dart::Dart_TestStackTraceMallocHookSimpleJSONTest()\"",
                    json);
   EXPECT_SUBSTRING("\"dart::TestCase::Run()\"", json);
   EXPECT_SUBSTRING("\"dart::TestCaseBase::RunTest()\"", json);
   EXPECT_SUBSTRING("\"main\"", json);
 
   free(var);
-  MallocHooks::TearDown();
-  MallocHooks::set_stack_trace_collection_enabled(enable_stack_traces_saved);
-  FLAG_profiler_native_memory = enable_malloc_hooks_saved;
 }
 
 };  // namespace dart
 
 #endif  // defined(DART_USE_TCMALLOC) && !defined(PRODUCT)