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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROME_BROWSER_SAFE_BROWSING_EXTENSION_TELEMETRY_EXTENSION_TELEMETRY_PERSISTER_H_
#define CHROME_BROWSER_SAFE_BROWSING_EXTENSION_TELEMETRY_EXTENSION_TELEMETRY_PERSISTER_H_
#include <memory>
#include "base/files/file_util.h"
#include "base/memory/weak_ptr.h"
#include "base/sequence_checker.h"
namespace base {
class FilePath;
}
namespace safe_browsing {
// The `ExtensionTelemetryPersister` stores data collected by the Extension
// Telemetry Service to disk. It creates files until `max_num_files_` are on
// disk and then starts overwriting previously made files. The Persister runs
// read and write functions that are time intensive. To avoid blocking
// important threads, the persister should be created using SequenceBound.
class ExtensionTelemetryPersister {
public:
// Indicates when the `WriteReport` function is called. Used to generate
// histogram suffixes.
enum class WriteReportTrigger { kAtWriteInterval = 0, kAtShutdown = 1 };
// The `profile_path` is used to construct where the persister saves it's
// files. The persister creates a directory under profile_path/CRX_Telemetry
// and saves files there.
explicit ExtensionTelemetryPersister(int max_num_files,
base::FilePath profile_path);
ExtensionTelemetryPersister(const ExtensionTelemetryPersister&) = delete;
ExtensionTelemetryPersister& operator=(const ExtensionTelemetryPersister&) =
delete;
virtual ~ExtensionTelemetryPersister();
// Determines if there are any existing telemetry reports on disk and
// initializes `read_index_` and `write_index_` for read and write operations.
void PersisterInit();
// Writes a telemetry report to a file on disk. The filename written is not
// exposed to the caller and is determined by `write_index_`. `trigger`
// indicates when the caller calls this function, used for logging
// histograms.
void WriteReport(const std::string write_string, WriteReportTrigger trigger);
// Reads a telemetry report from a file on disk. The file is deleted
// regardless of if the read was successful or not. The filename
// is not exposed to the caller. Returns a string representation
// of the read file, or an empty string if the read failed.
std::string ReadReport();
// Deletes the CRXTelemetry directory.
void ClearPersistedFiles();
// Returns the max size the persister cache can be.
static int MaxFilesSupported();
private:
// Deletes the file that the `path` variable points to.
// Returns true if the file is deleted, false otherwise.
bool DeleteFile(const base::FilePath path);
// Deletes the CRXTelemetry directory.
friend class ExtensionTelemetryPersisterTest;
// Stores the directory path where the telemetry files are persisted.
base::FilePath dir_path_;
// The maximum number of files that are stored on disk.
int max_num_files_;
// The index of which file is next for writing. `write_index_`
// increments from 0 to `kMaxNumFiles` - 1 and then back around to 0.
int write_index_;
// The index of which file is next for reading. `read_index_`
// increments and stops at `kMaxNumFiles` - 1. Allowing the
// persister to read from the highest numbered file first.
int read_index_;
// Ensures write and read operations are not called before the
// persister is done initializing.
bool initialization_complete_ = false;
SEQUENCE_CHECKER(sequence_checker_);
base::WeakPtrFactory<ExtensionTelemetryPersister> weak_factory_{this};
};
} // namespace safe_browsing
#endif // CHROME_BROWSER_SAFE_BROWSING_EXTENSION_TELEMETRY_EXTENSION_TELEMETRY_PERSISTER_H_
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