feat: Track timezone changes as breadcrumbs

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+### Features
+
+- Track timezone changes as breadcrumbs (#1930)
+
 ## 7.19.0
 
 ### Features

Sources/Sentry/SentryAutoBreadcrumbTrackingIntegration.m

@@ -1,6 +1,8 @@
 #import "SentryAutoBreadcrumbTrackingIntegration.h"
 #import "SentryBreadcrumbTracker.h"
+#import "SentryDefaultCurrentDateProvider.h"
 #import "SentryDependencyContainer.h"
+#import "SentryFileManager.h"
 #import "SentrySystemEventBreadcrumbs.h"
 
 NS_ASSUME_NONNULL_BEGIN
@@ -22,7 +24,11 @@ - (void)installWithOptions:(nonnull SentryOptions *)options
              breadcrumbTracker:[[SentryBreadcrumbTracker alloc]
                                    initWithSwizzleWrapper:[SentryDependencyContainer sharedInstance]
                                                               .swizzleWrapper]
-        systemEventBreadcrumbs:[[SentrySystemEventBreadcrumbs alloc] init]];
+        systemEventBreadcrumbs:[[SentrySystemEventBreadcrumbs alloc]
+                                      initWithFileManager:[SentryDependencyContainer sharedInstance]
+                                                              .fileManager
+                                   andCurrentDateProvider:[SentryDefaultCurrentDateProvider
+                                                              sharedInstance]]];
 }
 
 /**

Sources/Sentry/SentryDefaultCurrentDateProvider.m

@@ -27,6 +27,11 @@ - (dispatch_time_t)dispatchTimeNow
     return dispatch_time(DISPATCH_TIME_NOW, 0);
 }
 
+- (NSInteger)timezoneOffset
+{
+    return [NSTimeZone localTimeZone].secondsFromGMT;
+}
+
 @end
 
 NS_ASSUME_NONNULL_END

Sources/Sentry/SentryDependencyContainer.m

@@ -46,16 +46,25 @@ + (void)reset
     }
 }
 
+- (SentryFileManager *)fileManager
+{
+    @synchronized(sentryDependencyContainerLock) {
+        if (_fileManager == nil) {
+            _fileManager = [[[SentrySDK currentHub] getClient] fileManager];
+        }
+        return _fileManager;
+    }
+}
+
 - (SentryAppStateManager *)appStateManager
 {
     @synchronized(sentryDependencyContainerLock) {
         if (_appStateManager == nil) {
-            SentryFileManager *fileManager = [[[SentrySDK currentHub] getClient] fileManager];
             SentryOptions *options = [[[SentrySDK currentHub] getClient] options];
             _appStateManager = [[SentryAppStateManager alloc]
                     initWithOptions:options
                        crashWrapper:self.crashWrapper
-                        fileManager:fileManager
+                        fileManager:self.fileManager
                 currentDateProvider:[SentryDefaultCurrentDateProvider sharedInstance]
                              sysctl:[[SentrySysctl alloc] init]];
         }

Sources/Sentry/SentryFileManager.m

@@ -24,6 +24,7 @@
 @property (nonatomic, copy) NSString *crashedSessionFilePath;
 @property (nonatomic, copy) NSString *lastInForegroundFilePath;
 @property (nonatomic, copy) NSString *appStateFilePath;
+@property (nonatomic, copy) NSString *timezoneOffsetFilePath;
 @property (nonatomic, assign) NSUInteger currentFileCounter;
 @property (nonatomic, assign) NSUInteger maxEnvelopes;
 @property (nonatomic, weak) id<SentryFileManagerDelegate> delegate;
@@ -63,6 +64,8 @@ - (nullable instancetype)initWithOptions:(SentryOptions *)options
             [self.sentryPath stringByAppendingPathComponent:@"lastInForeground.timestamp"];
 
         self.appStateFilePath = [self.sentryPath stringByAppendingPathComponent:@"app.state"];
+        self.timezoneOffsetFilePath =
+            [self.sentryPath stringByAppendingPathComponent:@"timezone.offset"];
 
         // Remove old cached events for versions before 6.0.0
         self.eventsPath = [self.sentryPath stringByAppendingPathComponent:@"events"];
@@ -436,6 +439,66 @@ - (void)deleteAppState
     }
 }
 
+- (NSNumber *_Nullable)readTimezoneOffset
+{
+    [SentryLog logWithMessage:@"Reading timezone offset" andLevel:kSentryLevelDebug];
+    NSFileManager *fileManager = [NSFileManager defaultManager];
+    NSData *timezoneOffsetData = nil;
+    @synchronized(self.timezoneOffsetFilePath) {
+        timezoneOffsetData = [fileManager contentsAtPath:self.timezoneOffsetFilePath];
+    }
+    if (nil == timezoneOffsetData) {
+        [SentryLog logWithMessage:@"No timezone offset found." andLevel:kSentryLevelDebug];
+        return nil;
+    }
+    NSString *timezoneOffsetString = [[NSString alloc] initWithData:timezoneOffsetData
+                                                           encoding:NSUTF8StringEncoding];
+
+    NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
+    formatter.numberStyle = NSNumberFormatterDecimalStyle;
+
+    return [formatter numberFromString:timezoneOffsetString];
+}
+
+- (void)storeTimezoneOffset:(NSInteger)offset
+{
+    NSError *error = nil;
+    NSString *timezoneOffsetString = [NSString stringWithFormat:@"%zd", offset];
+    NSString *logMessage =
+        [NSString stringWithFormat:@"Persisting timezone offset: %@", timezoneOffsetString];
+    [SentryLog logWithMessage:logMessage andLevel:kSentryLevelDebug];
+    @synchronized(self.timezoneOffsetFilePath) {
+        [[timezoneOffsetString dataUsingEncoding:NSUTF8StringEncoding]
+            writeToFile:self.timezoneOffsetFilePath
+                options:NSDataWritingAtomic
+                  error:&error];
+
+        if (error != nil) {
+            [SentryLog
+                logWithMessage:[NSString
+                                   stringWithFormat:@"Failed to store timezone offset: %@", error]
+                      andLevel:kSentryLevelError];
+        }
+    }
+}
+
+- (void)deleteTimezoneOffset
+{
+    NSError *error = nil;
+    NSFileManager *fileManager = [NSFileManager defaultManager];
+    @synchronized(self.timezoneOffsetFilePath) {
+        [fileManager removeItemAtPath:self.timezoneOffsetFilePath error:&error];
+
+        // We don't want to log an error if the file doesn't exist.
+        if (nil != error && error.code != NSFileNoSuchFileError) {
+            [SentryLog
+                logWithMessage:[NSString
+                                   stringWithFormat:@"Failed to delete timezone offset %@", error]
+                      andLevel:kSentryLevelError];
+        }
+    }
+}
+
 + (BOOL)createDirectoryAtPath:(NSString *)path withError:(NSError **)error
 {
     NSFileManager *fileManager = [NSFileManager defaultManager];

Sources/Sentry/SentrySystemEventBreadcrumbs.m

@@ -1,5 +1,9 @@
 #import "SentrySystemEventBreadcrumbs.h"
+#import "SentryAppState.h"
+#import "SentryAppStateManager.h"
 #import "SentryBreadcrumb.h"
+#import "SentryCurrentDateProvider.h"
+#import "SentryDependencyContainer.h"
 #import "SentryLog.h"
 #import "SentrySDK.h"
 
@@ -8,8 +12,24 @@
 #    import <UIKit/UIKit.h>
 #endif
 
+@interface
+SentrySystemEventBreadcrumbs ()
+@property (nonatomic, strong) SentryFileManager *fileManager;
+@property (nonatomic, strong) id<SentryCurrentDateProvider> currentDateProvider;
+@end
+
 @implementation SentrySystemEventBreadcrumbs
 
+- (instancetype)initWithFileManager:(SentryFileManager *)fileManager
+             andCurrentDateProvider:(id<SentryCurrentDateProvider>)currentDateProvider
+{
+    if (self = [super init]) {
+        _fileManager = fileManager;
+        _currentDateProvider = currentDateProvider;
+    }
+    return self;
+}
+
 - (void)start
 {
 #if TARGET_OS_IOS
@@ -45,6 +65,7 @@ - (void)start:(UIDevice *)currentDevice
     }
     [self initKeyboardVisibilityObserver];
     [self initScreenshotObserver];
+    [self initTimezoneObserver];
 }
 #endif
 
@@ -177,6 +198,58 @@ - (void)initScreenshotObserver
                                                  name:UIApplicationUserDidTakeScreenshotNotification
                                                object:nil];
 }
+
+- (void)initTimezoneObserver
+{
+    // Detect if the stored timezone is different from the current one;
+    // if so, then we also send a breadcrumb
+    NSNumber *_Nullable storedTimezoneOffset = [self.fileManager readTimezoneOffset];
+
+    if (storedTimezoneOffset == nil) {
+        [self updateStoredTimezone];
+    } else if (storedTimezoneOffset.doubleValue != self.currentDateProvider.timezoneOffset) {
+        [self timezoneEventTriggered:storedTimezoneOffset];
+    }
+
+    // Posted when the timezone of the device changed
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                             selector:@selector(timezoneEventTriggered)
+                                                 name:NSSystemTimeZoneDidChangeNotification
+                                               object:nil];
+}
+
+- (void)timezoneEventTriggered
+{
+    [self timezoneEventTriggered:nil];
+}
+
+- (void)timezoneEventTriggered:(NSNumber *)storedTimezoneOffset
+{
+    if (storedTimezoneOffset == nil) {
+        storedTimezoneOffset = [self.fileManager readTimezoneOffset];
+    }
+
+    SentryBreadcrumb *crumb = [[SentryBreadcrumb alloc] initWithLevel:kSentryLevelInfo
+                                                             category:@"device.event"];
+
+    NSInteger offset = self.currentDateProvider.timezoneOffset;
+
+    crumb.type = @"system";
+    crumb.data = @{
+        @"action" : @"TIMEZONE_CHANGE",
+        @"previous_seconds_from_gmt" : storedTimezoneOffset,
+        @"current_seconds_from_gmt" : @(offset)
+    };
+    [SentrySDK addBreadcrumb:crumb];
+
+    [self updateStoredTimezone];
+}
+
+- (void)updateStoredTimezone
+{
+    [self.fileManager storeTimezoneOffset:self.currentDateProvider.timezoneOffset];
+}
+
 #endif
 
 @end

Sources/Sentry/include/SentryCurrentDateProvider.h

@@ -9,6 +9,8 @@ NS_SWIFT_NAME(CurrentDateProvider)
 
 - (dispatch_time_t)dispatchTimeNow;
 
+- (NSInteger)timezoneOffset;
+
 @end
 
 NS_ASSUME_NONNULL_END

Sources/Sentry/include/SentryDependencyContainer.h

@@ -1,4 +1,5 @@
 #import "SentryDefines.h"
+#import "SentryFileManager.h"
 #import "SentryRandom.h"
 #import <Foundation/Foundation.h>
 
@@ -21,6 +22,7 @@ SENTRY_NO_INIT
  */
 + (void)reset;
 
+@property (nonatomic, strong) SentryFileManager *fileManager;
 @property (nonatomic, strong) SentryAppStateManager *appStateManager;
 @property (nonatomic, strong) SentryCrashWrapper *crashWrapper;
 @property (nonatomic, strong) SentryThreadWrapper *threadWrapper;

Sources/Sentry/include/SentryFileManager.h

@@ -65,6 +65,10 @@ SENTRY_NO_INIT
 - (SentryAppState *_Nullable)readAppState;
 - (void)deleteAppState;
 
+- (NSNumber *_Nullable)readTimezoneOffset;
+- (void)storeTimezoneOffset:(NSInteger)offset;
+- (void)deleteTimezoneOffset;
+
 @end
 
 @protocol SentryFileManagerDelegate <NSObject>

Sources/Sentry/include/SentrySystemEventBreadcrumbs.h

@@ -1,10 +1,16 @@
+#import "SentryAppStateManager.h"
+#import "SentryCurrentDateProvider.h"
 #import <Foundation/Foundation.h>
 
 #if TARGET_OS_IOS
 #    import <UIKit/UIKit.h>
 #endif
 
 @interface SentrySystemEventBreadcrumbs : NSObject
+SENTRY_NO_INIT
+
+- (instancetype)initWithFileManager:(SentryFileManager *)fileManager
+             andCurrentDateProvider:(id<SentryCurrentDateProvider>)currentDateProvider;
 
 - (void)start;
 

Tests/SentryTests/Helper/SentryAppStateTests.swift

@@ -44,7 +44,7 @@ class SentryAppStateTests: XCTestCase {
         withValue { $0["was_terminated"] = nil }
         withValue { $0["is_anr_ongoing"] = nil }
     }
-    
+
     func testInitWithJSON_IfJsonContainsWrongField_AppStateIsNil() {
         withValue { $0["release_name"] = 0 }
         withValue { $0["os_version"] = nil }
@@ -72,5 +72,4 @@ class SentryAppStateTests: XCTestCase {
         setValue(&serialized)
         XCTAssertNil(SentryAppState(jsonObject: serialized))
     }
-
 }

Tests/SentryTests/Helper/SentryFileManager+TestProperties.h

@@ -13,6 +13,8 @@ SentryFileManager (TestProperties)
 
 @property (nonatomic, copy) NSString *envelopesPath;
 
+@property (nonatomic, copy) NSString *timezoneOffsetFilePath;
+
 @end
 
 NS_ASSUME_NONNULL_END