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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_METRICS_STRUCTURED_EXTERNAL_METRICS_H_
#define COMPONENTS_METRICS_STRUCTURED_EXTERNAL_METRICS_H_
#include "base/containers/flat_set.h"
#include "base/files/file_path.h"
#include "base/functional/callback.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/task/sequenced_task_runner.h"
#include "base/time/time.h"
namespace metrics::structured {
class EventsProto;
class ExternalMetricsTest;
// ExternalMetrics reads structured metrics saved by ChromeOS and uploads them
// to the UMA server on its behalf. This is structured metrics' equivalent of
// `ash::ExternalMetrics`.
//
// When a call to CollectEvents() is done, events in that directory will be
// added to StructuredMetricsRecorder. However, if the user has disabled upload,
// then all events will be dropped and deleted.
//
// Chrome periodically reads a directory of protos and adds their content into
// the StructuredMetricProvider's regular metrics upload. After reading each
// file, it is deleted. Chrome and ChromeOS use flock to prevent concurrent
// read/writes.
class ExternalMetrics {
public:
using MetricsCollectedCallback =
base::RepeatingCallback<void(const EventsProto&)>;
ExternalMetrics(const base::FilePath& events_directory,
const base::TimeDelta& collection_interval,
MetricsCollectedCallback callback);
~ExternalMetrics();
ExternalMetrics(const ExternalMetrics&) = delete;
ExternalMetrics& operator=(const ExternalMetrics&) = delete;
// Adds a project to the disallowed list for testing.
void AddDisallowedProjectForTest(uint64_t project_name_hash);
void EnableRecording();
void DisableRecording();
private:
friend class ExternalMetricsTest;
void ScheduleCollector();
void CollectEventsAndReschedule();
// Events are collected from |events_directory|. Each file is processed by:
//
// 1. Stat on a file to see if it contains any events or if
// something in ChromeOS has already deleted the file.
// 2. Obtains a flock.
// 3. File is processed and read into memory.
// 4. File is deleted.
// 5. Flock is released.
//
// The above is done to avoid reading files mid-write from ChromeOS and having
// ChromeOS write files after they were marked for deletion by Chrome.
//
// Files will be ignored if there is failure to obtain the flock or get the
// file descriptor.
//
// Files will be dropped when an event file exceeds a fixed threshold provided
// by GetFileSizeByteLimit(). Files will also be dropped if there are too many
// event files existing on the current iteration provided by
// GetFileLimitPerScan().
void CollectEvents();
// Builds a cache of disallow projects from the Finch controlled variable.
void CacheDisallowedProjectsSet();
bool recording_enabled_ = false;
const base::FilePath events_directory_;
const base::TimeDelta collection_interval_;
MetricsCollectedCallback callback_;
// A set of projects that are not allowed to be recorded. This is a cache of
// GetDisabledProjects().
base::flat_set<uint64_t> disallowed_projects_;
scoped_refptr<base::SequencedTaskRunner> task_runner_;
base::WeakPtrFactory<ExternalMetrics> weak_factory_{this};
};
} // namespace metrics::structured
#endif // COMPONENTS_METRICS_STRUCTURED_EXTERNAL_METRICS_H_
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