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// Copyright (c) 2010 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 <string>
#include "base/compiler_specific.h"
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/time/time.h"
namespace metrics {
class MetricSample;
} // namespace metrics
namespace chromeos {
// ExternalMetrics is a service that Chrome offers to Chrome OS to upload
// metrics to the UMA server on its behalf. Chrome periodically reads the
// content of a well-know file, and parses it into name-value pairs, each
// representing a Chrome OS metrics event. The events are logged using the
// normal UMA mechanism. The file is then truncated to zero size. Chrome uses
// flock() to synchronize accesses to the file.
class ExternalMetrics : public base::RefCountedThreadSafe<ExternalMetrics> {
// Begins the external data collection. This service is started and stopped
// by the chrome metrics service. Calls to RecordAction originate in the
// blocking pool but are executed in the UI thread.
void Start();
// Creates an ExternalMetrics instance reading from |filename| for testing
// purpose.
static scoped_refptr<ExternalMetrics> CreateForTesting(
const std::string& filename);
friend class base::RefCountedThreadSafe<ExternalMetrics>;
friend class ExternalMetricsTest;
FRIEND_TEST_ALL_PREFIXES(ExternalMetricsTest, CustomInterval);
FRIEND_TEST_ALL_PREFIXES(ExternalMetricsTest, HandleMissingFile);
FRIEND_TEST_ALL_PREFIXES(ExternalMetricsTest, CanReceiveHistogram);
// The max length of a message (name-value pair, plus header)
static const int kMetricsMessageMaxLength = 1024; // be generous
// Passes an action event to the UMA service on the UI thread.
void RecordActionUI(const std::string& action_string);
// Passes an action event to the UMA service.
void RecordAction(const std::string& action_name);
// Records an external crash of the given string description to
// UMA service on the UI thread.
void RecordCrashUI(const std::string& crash_kind);
// Records an external crash of the given string description.
void RecordCrash(const std::string& crash_kind);
// Records an histogram. |sample| is expected to be an histogram.
void RecordHistogram(const metrics::MetricSample& sample);
// Records a sparse histogram. |sample| is expected to be a sparse histogram.
void RecordSparseHistogram(const metrics::MetricSample& sample);
// Records a linear histogram. |sample| is expected to be a linear histogram.
void RecordLinearHistogram(const metrics::MetricSample& sample);
// Collects external events from metrics log file. This is run at periodic
// intervals.
// Returns the number of events collected.
int CollectEvents();
// Calls CollectEvents and reschedules a future collection.
void CollectEventsAndReschedule();
// Schedules a metrics event collection in the future.
void ScheduleCollector();
// File used by libmetrics to send metrics to Chrome.
std::string uma_events_file_;
// Interval between metrics being read from |uma_events_file_|.
base::TimeDelta collection_interval_;
} // namespace chromeos