metrics: Add leak detector controller in Chrome OS metrics system

components/metrics/leak_detector/leak_detector_unittest.cc

+// Copyright 2016 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 "components/metrics/leak_detector/leak_detector.h"
+
+#include <set>
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/public/test/test_browser_thread_bundle.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace metrics {
+
+namespace {
+
+// Default values for LeakDetector params. See header file for the meaning of
+// each parameter.
+const float kDefaultSamplingRate = 1.0f;
+const size_t kDefaultMaxCallStackUnwindDepth = 4;
+const uint64_t kDefaultAnalysisIntervalBytes = 32 * 1024 * 1024;  // 32 MiB.
+const uint32_t kDefaultSizeSuspicionThreshold = 4;
+const uint32_t kDefaultCallStackSuspicionThreshold = 4;
+
+using LeakReport = LeakDetector::LeakReport;
+
+// Observer class that receives leak reports and stores them in |reports_|.
+// Only one copy of each unique report will be stored.
+class TestObserver : public LeakDetector::Observer {
+ public:
+  // Contains a comparator function used to compare LeakReports for uniqueness.
+  struct Comparator {
+    bool operator()(const LeakReport& a, const LeakReport& b) const {
+      if (a.alloc_size_bytes != b.alloc_size_bytes)
+        return a.alloc_size_bytes < b.alloc_size_bytes;
+
+      return a.call_stack < b.call_stack;
+    }
+  };
+
+  TestObserver() {}
+
+  void OnLeakFound(const LeakReport& report) override {
+    reports_.insert(report);
+  }
+
+  const std::set<LeakReport, Comparator>& reports() const { return reports_; }
+
+ private:
+  // Container for all leak reports received through OnLeakFound(). Stores only
+  // one copy of each unique report.
+  std::set<LeakReport, Comparator> reports_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestObserver);
+};
+
+}  // namespace
+
+class LeakDetectorTest : public ::testing::Test {
+ public:
+  LeakDetectorTest()
+      : detector_(new LeakDetector(kDefaultSamplingRate,
+                                   kDefaultMaxCallStackUnwindDepth,
+                                   kDefaultAnalysisIntervalBytes,
+                                   kDefaultSizeSuspicionThreshold,
+                                   kDefaultCallStackSuspicionThreshold)) {}
+
+ protected:
+  // Use a scoped_ptr to hold the test object so it can be destroyed before the
+  // test is over.
+  scoped_ptr<LeakDetector> detector_;
+
+ private:
+  // For supporting content::BrowserThread operations.
+  content::TestBrowserThreadBundle thread_bundle_;
+
+  DISALLOW_COPY_AND_ASSIGN(LeakDetectorTest);
+};
+
+TEST_F(LeakDetectorTest, NotifyObservers) {
+  // Generate two sets of leak reports.
+  std::vector<LeakReport> reports1(3);
+  reports1[0].alloc_size_bytes = 8;
+  reports1[0].call_stack = {1, 2, 3, 4};
+  reports1[1].alloc_size_bytes = 16;
+  reports1[1].call_stack = {5, 6, 7, 8};
+  reports1[2].alloc_size_bytes = 24;
+  reports1[2].call_stack = {9, 10, 11, 12};
+
+  std::vector<LeakReport> reports2(3);
+  reports2[0].alloc_size_bytes = 32;
+  reports2[0].call_stack = {1, 2, 4, 8};
+  reports2[1].alloc_size_bytes = 40;
+  reports2[1].call_stack = {16, 32, 64, 128};
+  reports2[2].alloc_size_bytes = 48;
+  reports2[2].call_stack = {256, 512, 1024, 2048};
+
+  // Register three observers;
+  TestObserver obs1, obs2, obs3;
+  detector_->AddObserver(&obs1);
+  detector_->AddObserver(&obs2);
+  detector_->AddObserver(&obs3);
+
+  // Pass both sets of reports to the leak detector.
+  detector_->NotifyObservers(reports1);
+  detector_->NotifyObservers(reports2);
+
+  // Shut down the leak detector before checking the reports, so that the
+  // stored reports can be examined without new reports being generated.
+  detector_.reset();
+
+  // Check that all three observers got both sets of reports, passed in
+  // separately.
+  for (const TestObserver* obs : {&obs1, &obs2, &obs3}) {
+    EXPECT_EQ(6U, obs->reports().size());
+    for (const auto& report : {reports1[0], reports1[1], reports1[2],
+                               reports2[0], reports2[1], reports2[2]}) {
+      EXPECT_TRUE(obs->reports().find(report) != obs->reports().end());
+    }
+  }
+}
+
+}  // namespace metrics