Adds a method to the Performance Monitor Database to fetch the most recent metric.

BUG=130212
TEST=database_unittest gets the most recent metric


Review URL: https://chromiumcodereview.appspot.com/10843010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@149668 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/performance_monitor/database.cc

@@ -11,6 +11,7 @@
 #include "base/json/json_writer.h"
 #include "base/logging.h"
 #include "base/path_service.h"
+#include "base/stl_util.h"
 #include "base/string_number_conversions.h"
 #include "base/string_split.h"
 #include "base/stringprintf.h"
@@ -379,6 +380,23 @@ std::vector<std::string> Database::GetActiveActivities(
   return results;
 }
 
+bool Database::GetRecentStatsForActivityAndMetric(
+    const std::string& activity,
+    MetricType metric,
+    MetricInfo* info) {
+  CHECK(!content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  std::string recent_map_key = CreateRecentMapKey(metric, activity);
+  if (!ContainsKey(recent_map_, recent_map_key))
+    return false;
+  std::string recent_key = recent_map_[recent_map_key];
+
+  std::string result;
+  leveldb::Status status = recent_db_->Get(read_options_, recent_key, &result);
+  if (status.ok())
+    *info = MetricInfo(SplitRecentKey(recent_key).time, result);
+  return status.ok();
+}
+
 Database::MetricInfoVector Database::GetStatsForActivityAndMetric(
     const std::string& activity, MetricType metric_type,
     const base::Time& start, const base::Time& end) {

chrome/browser/performance_monitor/database.h

@@ -158,6 +158,18 @@ class Database {
   std::vector<std::string> GetActiveActivities(MetricType metric_type,
                                                const base::Time& start);
 
+  // Populate info with the most recent activity. Return false if populate
+  // was unsuccessful.
+  bool GetRecentStatsForActivityAndMetric(const std::string& activity,
+                                          MetricType metric,
+                                          MetricInfo* info);
+
+  bool GetRecentStatsForActivityAndMetric(MetricType metric, MetricInfo* info) {
+    return GetRecentStatsForActivityAndMetric(kProcessChromeAggregate,
+                                              metric,
+                                              info);
+  }
+
   // Query given |metric_type| and |activity|.
   MetricInfoVector GetStatsForActivityAndMetric(const std::string& activity,
                                                 MetricType metric_type,

chrome/browser/performance_monitor/database_unittest.cc

@@ -285,6 +285,23 @@ TEST_F(PerformanceMonitorDatabaseMetricTest, GetActiveMetrics) {
   EXPECT_EQ(expected_metrics, active_metrics);
 }
 
+TEST_F(PerformanceMonitorDatabaseMetricTest, GetRecentMetric) {
+  MetricInfo stat;
+  ASSERT_TRUE(db_->GetRecentStatsForActivityAndMetric(activity_,
+      METRIC_PRIVATE_MEMORY_USAGE, &stat));
+  EXPECT_EQ(3000000, stat.value);
+
+  ASSERT_TRUE(db_->GetRecentStatsForActivityAndMetric(METRIC_CPU_USAGE, &stat));
+  EXPECT_EQ(50.5, stat.value);
+
+  ScopedTempDir dir;
+  CHECK(dir.CreateUniqueTempDir());
+  scoped_ptr<Database> db = Database::Create(dir.path());
+  CHECK(db.get());
+  db->set_clock(scoped_ptr<Database::Clock>(new TestingClock()));
+  EXPECT_FALSE(db->GetRecentStatsForActivityAndMetric(METRIC_CPU_USAGE, &stat));
+}
+
 TEST_F(PerformanceMonitorDatabaseMetricTest, GetState) {
   std::string key("version");
   std::string value("1.0.0.0.1");