Windows-native sampling profiler wrapper class.

base/win/sampling_profiler_unittest.cc

Index: base/win/sampling_profiler_unittest.cc
diff --git a/base/win/sampling_profiler_unittest.cc b/base/win/sampling_profiler_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..caa4c63af0dc6b0912702be0184d5ad78de2eb92
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+++ b/base/win/sampling_profiler_unittest.cc
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+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/win/sampling_profiler.h"
+
+#include "base/test/test_timeouts.h"
+#include "base/win/pe_image.h"
+#include "base/win/scoped_handle.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+// The address of our image base.
+extern "C" IMAGE_DOS_HEADER __ImageBase;
+
+namespace base {
+namespace win {
+
+namespace {
+
+class SamplingProfilerTest : public testing::Test {
+ public:
+  SamplingProfilerTest() : code_start(NULL), code_size(0) {
+  }
+
+  virtual void SetUp() {
+    process.Set(::OpenProcess(PROCESS_QUERY_INFORMATION,
+                              FALSE,
+                              ::GetCurrentProcessId()));
+    ASSERT_TRUE(process.IsValid());
+
+    PEImage image(&__ImageBase);
+
+    // Get the address of the .text section, which is the first section output
+    // by the VS tools.
+    ASSERT_TRUE(image.GetNumSections() > 0);
+    const IMAGE_SECTION_HEADER* text_section = image.GetSectionHeader(0);
+    ASSERT_EQ(0, strncmp(".text",
+                         reinterpret_cast<const char*>(text_section->Name),
+                         arraysize(text_section->Name)));
+    ASSERT_NE(0U, text_section->Characteristics & IMAGE_SCN_MEM_EXECUTE);
+
+    code_start = reinterpret_cast<uint8*>(&__ImageBase) +
+        text_section->VirtualAddress;
+    code_size = text_section->Misc.VirtualSize;
+  }
+
+ protected:
+  ScopedHandle process;
+  void* code_start;
+  size_t code_size;
+};
+
+}  // namespace
+
+TEST_F(SamplingProfilerTest, Initialize) {
+  SamplingProfiler profiler;
+
+  ASSERT_TRUE(profiler.Initialize(process.Get(), code_start, code_size, 8));
+}
+
+TEST_F(SamplingProfilerTest, Sample) {
+  SamplingProfiler profiler;
+
+  // Initialize with a huge bucket size, aiming for a single bucket.
+  ASSERT_TRUE(
+      profiler.Initialize(process.Get(), code_start, code_size, 31));
+
+  ASSERT_EQ(1, profiler.buckets().size());
+  ASSERT_EQ(0, profiler.buckets()[0]);
+
+  // We use a roomy timeout to make sure this test is not flaky.
+  // On the buildbots, there may not be a whole lot of CPU time
+  // allotted to our process in this wall-clock time duration,
+  // and samples will only accrue while this thread is busy on
+  // a CPU core.
+  base::TimeDelta spin_time =
+      base::TimeDelta::FromMilliseconds(TestTimeouts::action_timeout_ms());
+
+  base::TimeDelta save_sampling_interval;
+  ASSERT_TRUE(SamplingProfiler::GetSamplingInterval(&save_sampling_interval));
+
+  // Sample every 0.5 millisecs.
+  ASSERT_TRUE(SamplingProfiler::SetSamplingInterval(
+      base::TimeDelta::FromMicroseconds(500)));
+
+  ASSERT_TRUE(SamplingProfiler::SetSamplingInterval(
+      base::TimeDelta::FromMicroseconds(500)));
+
+  // Start the profiler.
+  ASSERT_TRUE(profiler.Start());
+
+  // Get a volatile pointer to our bucket to make sure that the compiler
+  // doesn't optimize out the test in the loop that follows.
+  volatile const ULONG* bucket_ptr = &profiler.buckets()[0];
+
+  // Spin for spin_time wall-clock seconds, or until we get some samples.
+  // Note that sleeping isn't going to do us any good, the samples only
+  // accrue while we're executing code.
+  base::Time start = base::Time::Now();
+  base::TimeDelta elapsed;
+  do {
+    elapsed = base::Time::Now() - start;
+  } while((elapsed < spin_time) && *bucket_ptr == 0);
+
+  // Stop the profiler.
+  ASSERT_TRUE(profiler.Stop());
+
+  // Restore the sampling interval we found.
+  ASSERT_TRUE(SamplingProfiler::SetSamplingInterval(save_sampling_interval));
+
+  // Check that we got some samples.
+  ASSERT_NE(0U, profiler.buckets()[0]);
+}
+
+}  // namespace win
+}  // namespace base