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// Copyright 2014 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_CLEAN_EXIT_BEACON_H_
#define COMPONENTS_METRICS_CLEAN_EXIT_BEACON_H_
#include <optional>
#include <string>
#include "base/files/file_path.h"
#include "base/memory/raw_ptr.h"
#include "base/time/time.h"
#include "base/values.h"
#include "build/build_config.h"
class PrefRegistrySimple;
class PrefService;
namespace metrics {
// The name of the beacon file, which is relative to the user data directory
// and used to store the CleanExitBeacon value and the variations crash streak.
extern const base::FilePath::CharType kCleanExitBeaconFilename[];
// Captures all possible beacon value permutations for two distinct beacons.
// Exposed for testing.
//
// These values are persisted to logs. Entries should not be renumbered and
// numeric values should never be reused.
enum class CleanExitBeaconConsistency {
kCleanClean = 0,
kCleanDirty = 1,
kCleanMissing = 2,
kDirtyClean = 3,
kDirtyDirty = 4,
kDirtyMissing = 5,
kMissingClean = 6,
kMissingDirty = 7,
kMissingMissing = 8,
kMaxValue = kMissingMissing,
};
// Denotes the state of the beacon file. Exposed for testing.
//
// These values are persisted to logs. Entries should not be renumbered and
// numeric values should never be reused.
enum class BeaconFileState {
kReadable = 0,
kNotDeserializable = 1,
kMissingDictionary = 2,
kMissingCrashStreak = 3,
kMissingBeacon = 4,
kMaxValue = kMissingBeacon,
};
// Reads and updates a beacon used to detect whether the previous browser
// process exited cleanly.
class CleanExitBeacon {
public:
// Instantiates a CleanExitBeacon whose value is stored in
// |has_exited_cleanly_|. The value is persisted in the beacon file on
// platforms that support this mechanism and in Local State on platforms that
// don't.
//
// On Windows, |backup_registry_key| stores a backup of the beacon to verify
// that the pref's value corresponds to the registry's. |backup_registry_key|
// is ignored on other platforms, but iOS has a similar verification
// mechanism embedded inside CleanExitBeacon.
//
// |user_data_dir| is the path to the client's user data directory. If empty,
// the beacon file is not used.
CleanExitBeacon(const std::wstring& backup_registry_key,
const base::FilePath& user_data_dir,
PrefService* local_state);
virtual ~CleanExitBeacon() = default;
// Not copyable or movable.
CleanExitBeacon(const CleanExitBeacon&) = delete;
CleanExitBeacon& operator=(const CleanExitBeacon&) = delete;
// Initializes the CleanExitBeacon. This includes the following tasks:
// 1. Determining if the last session exited cleanly,
// 2. Incrementing the crash streak, if necessary, and
// 3. Emitting some metrics.
void Initialize();
// Returns the original value of the beacon.
bool exited_cleanly() const { return did_previous_session_exit_cleanly_; }
// Returns the original value of the last live timestamp.
base::Time browser_last_live_timestamp() const {
return initial_browser_last_live_timestamp_;
}
// Returns true if Extended Variations Safe Mode is supported on this
// platform. Android WebLayer and WebView do not support this.
bool IsExtendedSafeModeSupported() const;
// Sets the beacon value to |exited_cleanly| and writes the value to disk if
// the current value (see has_exited_cleanly_) is not already
// |exited_cleanly|. Note that on platforms that do not support the beacon
// file, the write is scheduled, so the value may not be persisted if the
// browser process crashes.
//
// Also, updates the last live timestamp.
//
// |is_extended_safe_mode| denotes whether Chrome is about to start watching
// for browser crashes early on in startup as a part of Extended Variations
// Safe Mode, which is supported by most, but not all, platforms.
//
// TODO(crbug.com/40850854): Consider removing |is_extended_safe_mode|.
void WriteBeaconValue(bool exited_cleanly,
bool is_extended_safe_mode = false);
// Updates the last live timestamp.
void UpdateLastLiveTimestamp();
const base::FilePath GetUserDataDirForTesting() const;
base::FilePath GetBeaconFilePathForTesting() const;
// Registers local state prefs used by this class.
static void RegisterPrefs(PrefRegistrySimple* registry);
// Updates both Local State and NSUserDefaults beacon values.
static void SetStabilityExitedCleanlyForTesting(PrefService* local_state,
bool exited_cleanly);
// Creates and returns a well-formed beacon file contents with the given
// values.
static std::string CreateBeaconFileContentsForTesting(bool exited_cleanly,
int crash_streak);
// Resets both Local State and NSUserDefaults beacon values.
static void ResetStabilityExitedCleanlyForTesting(PrefService* local_state);
// CHECKs that Chrome exited cleanly.
static void EnsureCleanShutdown(PrefService* local_state);
#if BUILDFLAG(IS_IOS)
// Sets the NSUserDefaults beacon value.
static void SetUserDefaultsBeacon(bool exited_cleanly);
// Checks user default value of kUseUserDefaultsForExitedCleanlyBeacon.
// Because variations are not initialized early in startup, pair a user
// defaults value with the variations config.
static bool ShouldUseUserDefaultsBeacon();
// Syncs feature kUseUserDefaultsForExitedCleanlyBeacon to NSUserDefaults
// kUserDefaultsFeatureFlagForExitedCleanlyBeacon.
static void SyncUseUserDefaultsBeacon();
#endif // BUILDFLAG(IS_IOS)
// Prevents a test browser from performing two clean shutdown steps. First, it
// prevents the beacon value from being updated after this function is called.
// This prevents the the test browser from signaling that Chrome is shutting
// down cleanly. Second, it makes EnsureCleanShutdown() a no-op.
static void SkipCleanShutdownStepsForTesting();
private:
// Returns true if the previous session exited cleanly. Either Local State
// or |beacon_file_contents| is used to get this information. Which is used
// depends on the client's platform and the existence of a valid beacon file.
// Also, records several metrics.
//
// Should be called only once: at startup.
bool DidPreviousSessionExitCleanly(base::Value* beacon_file_contents);
// Returns true if the beacon file is supported on this platform. Android
// WebLayer and WebView do not support this.
bool IsBeaconFileSupported() const;
// Writes |exited_cleanly| and the crash streak to the file located at
// |beacon_file_path_|.
void WriteBeaconFile(bool exited_cleanly) const;
#if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_IOS)
// Returns whether Chrome exited cleanly in the previous session according to
// the platform-specific beacon (the registry for Windows or NSUserDefaults
// for iOS). Returns std::nullopt if the platform-specific location does not
// have beacon info.
std::optional<bool> ExitedCleanly();
#endif // BUILDFLAG(IS_WIN) || BUILDFLAG(IS_IOS)
#if BUILDFLAG(IS_IOS)
// Returns true if the NSUserDefaults beacon value is set.
static bool HasUserDefaultsBeacon();
// Returns the NSUserDefaults beacon value.
static bool GetUserDefaultsBeacon();
// Clears the NSUserDefaults beacon value.
static void ResetUserDefaultsBeacon();
#endif // BUILDFLAG(IS_IOS)
// Indicates whether the CleanExitBeacon has been initialized.
bool initialized_ = false;
// Stores a backup of the beacon. Windows only.
const std::wstring backup_registry_key_;
// Path to the client's user data directory. May be empty.
const base::FilePath user_data_dir_;
const raw_ptr<PrefService> local_state_;
// This is the value of the last live timestamp from local state at the time
// of construction. It is a timestamp from the previous browser session when
// the browser was known to be alive.
const base::Time initial_browser_last_live_timestamp_;
bool did_previous_session_exit_cleanly_ = false;
// Denotes the current beacon value for this session, which is updated via
// CleanExitBeacon::WriteBeaconValue(). When `false`, Chrome is watching for
// browser crashes. When `true`, Chrome has stopped watching for crashes. When
// unset, Chrome has neither started nor stopped watching for crashes.
std::optional<bool> has_exited_cleanly_ = std::nullopt;
// Where the clean exit beacon and the variations crash streak are stored on
// platforms that support the beacon file.
base::FilePath beacon_file_path_;
};
} // namespace metrics
#endif // COMPONENTS_METRICS_CLEAN_EXIT_BEACON_H_