Backtrace Unity support

Backtrace's integration with Unity allows developers to capture and report handled and unhandled Unity exceptions and crashes to their Backtrace instance, instantly offering the ability to prioritize and debug software errors.

• Features Summary
• Prerequisites
• Platforms Supported
• Setup
• Android Specific information
• iOS Specific information
• API Overview
• Architecture description
• Investigating an Error in Backtrace

Usage

 //Read from manager BacktraceClient instance
var backtraceClient = GameObject.Find("_Manager").GetComponent<BacktraceClient>();
try{
    //throw exception here
}
catch(Exception exception){
    var report = new BacktraceReport(exception);
    backtraceClient.Send(report);
}

Feature Summary

• Lightweight library that quickly submits handled and unhandled exceptions and crashes to Backtrace
  • Supports wide range of Unity versions (2017.4+) and deployments (iOS, Android, Windows, Mac, WebGL, PS4, Xbox, Switch, Stadia)
  • Install via Universal Package Manager
• Collect detailed context
  • Callstacks, including function names and line numbers where possible
  • System metadata including device GUID, OS version, memory usage, process age
  • Custom metadata including app version, scene info, device drivers
  • Last # log lines, screenshots, log or config files, other attachments
  • Android NDK Crashes; iOS Native Crashes, Windows Native Crashes
• Client-side features
  • Deduplication options and custom client side fingerprinting
  • Offline crash capture/storage for future collection
  • Customizable event handlers and base classes, Client side filters
  • Performance statistics collection option for timing observability
• Unity IDE integration to configure Backtrace behaviors in your game.

Prerequisites

• Unity environment 2017.4.x
• .NET 2.0/3.5/4.5/Standard 2.0 scripting runtime version
• Mono or IL2CPP scripting backend

Platforms Supported

Backtrace-unity has been tested and certified for games deployed on the following platforms: Mobile - Android, iOS PC - Windows, Mac Web - WebGL Game Consoles - PlayStation4, Xbox One, Nintendo Switch There are some differences in capabilities that backtrace-unity provides based on the platform. Major capabilities are summarized as follows:

• All Platforms - Unhandled Exceptions, Handled Exceptions, Custom Indexable Metadata, File Attachments*, Last N Log Lines, Automatic attachment of Screenshots, Client Side Deduplication Rules*, Client Side Submission Filtering, Client Side Submission Limits, Performance Diagnostics, Offline Database*(Except Nintendo Switch)
• Android -Identified by attribute uname.sysname = Android; ANRs (Hangs), Native Process and Memory Information, Java Exception Handler (Plugins, Exported Game in Android Studio), NDK crashes.
• iOS - Identified by attribute uname.sysname = IOS; Native Engine and Plugin Crashes.
• WebGL - Identified by attribute uname.sysname = WebGL. The attribute device.model is currently used to share the browser information.
• Switch - Identified by attribute uname.sysname = Switch. Note that the attribute GUID is regenerated with each Switch restart (It is not an accurate count of number of Users or Devices. It is a count of Switch Sessions). Note that the current release does no support Offline Database or related features.
• PlayStation4 - Identified by attribute uname.sysname = PS4
• Windows - Identified by attribute uname.sysname = Windows. Provides an option to capture Minidumps for Engine Crashes.
• MacOS - Identified by attribute uname.sysname = MacOS.

Note: Unity allows you to disable stack trace information in player properties. If this is set, the call stack and the log lines section in Backtrace will be empty.

Setup

List of steps necessary to setup full Backtrace Unity integration.

Installation guide

• Download the backtrace-unity zip file. Unzip it and keep the folder in a known location. It can be downloaded from https://github.com/backtrace-labs/backtrace-unity/releases
• Open your Unity project
• Use the Unity Package Manager to install the backtrace-unity library (Window -> Package Manager -> Add Package From Disk)

Integrating into your project

• Under the Assets Menu "Create" option, there is now a Backtrace -> Configuration option. Choose that option (or Right click on empty space and select from the menu box) to have a Backtrace Configuration is generated in the Assets folder. You can drag and drop generated asset file into Backtrace Client configuration window.
• Next, select an object from the Scene Hierarchy to associate the Backtrace reporting client to. In the example below, we use the Manager object., Using the Inspector panel, click the Add Component button and search for the Backtrace Client object.
• Within the Backtrace Client panel, there is a Backtrace Configuration field. Drag and drop the Backtrace Configuration from the Assets folder to that field. More fields will appear for you to fill in to configure the Backtrace Client and Offline Database options.
• Provide valid Backtrace client configuration and start using library!

Plugin best practices

Plugin allows you to define maximum depth of game objects. By default its disabled (Game object depth is equal to -1). If you will use 0 as maximum depth of game object we will use default game object limit - 16. If you would like to specify game object depth size to n, please insert n in Backtrace configuration text box. If you require game obejct depth to be above 30, please contact support.

Backtrace Client and Offline Database Settings

The following is a reference guide to the Backtrace Client fields:

• Server Address: This field is required to submit exceptions from your Unity project to your Backtrace instance. More information about how to retrieve this value for your instance is our docs at What is a submission URL and What is a submission token? NOTE: the backtrace-unity plugin will expect full URL with token to your Backtrace instance,
• Reports per minute: Limits the number of reports the client will send per minutes. If set to 0, there is no limit. If set to a higher value and the value is reached, the client will not send any reports until the next minute. Further, the BacktraceClient.Send/BacktraceClient.SendAsync method will return false.
• Destroy client on new scene load - Backtrace-client by default will be available on each scene. Once you initialize Backtrace integration, you can fetch Backtrace game object from every scene. In case if you don't want to have Backtrace-unity integration available by default in each scene, please set this value to true.
• Use normalized exception message: If exception does not have a stack trace, use a normalized exception message to generate fingerprint.
• Filter reports: Configure Backtrace plugin to filter reports based on report type - Message, Exception, Unhandled Exception, Hang. By default this option is disabled (None).
• Send unhandled native game crashes on startup: Try to find game native crashes and send them on Game startup.
• Handle unhandled exceptions: Toggle this on or off to set the library to handle unhandled exceptions that are not captured by try-catch blocks.
• Symbols upload token - If you want to upload Unity debug symbols for Android NDK Native Crash debugging, enter your Backtrace Symbol upload token here. This option is available only in Android build.
• Game Object Depth Limit: Allows developer to filter number of game object childrens in Backtrace report.
• Collect last n game logs: Collect last n number of logs generated by game.
• Enabled performance statistics: Allows BacktraceClient to measure execution time and include performance information as report attributes.
• Ignore SSL validation: Unity by default will validate ssl certificates. By using this option you can avoid ssl certificates validation. However, if you don't need to ignore ssl validation, please set this option to false.
• Handle ANR (Application not responding) - this options is available only in Android build. It allows to catch ANR (application not responding) events happened to your game in Android devices. In this release, ANR is set to detect after 5 seconds. This will be configurable in a future release.
• Enable Database: When this setting is toggled, the backtrace-unity plugin will configure an offline database that will store reports if they can't be submitted do to being offline or not finding a network. When toggled on, there are a number of Database settings to configure.
• Backtrace Database path: This is the path to directory where the Backtrace database will store reports on your game. You can use interpolated strings SUCH AS ${Application.persistentDataPath}/backtrace/database to dynamically look up a known directory structure to use. NOTE: Backtrace database will remove all existing files in the database directory upion first initialization.
• Create database directory toggle: If toggled, the library will create the offline database directory if the provided path doesn't exists,
• Client-side deduplication: Backtrace-unity plugin allows you to combine the same reports. By using deduplication rules, you can tell backtrace-unity plugin how we should merge reports.
• Capture native crashes: This option will appear for games being deployed to Android or iOS and will allow Backtrace to capture and symbolicate native stack traces from crashes impacting the Unity Engine or any Unity Plugin.
• Minidump type: Type of minidump that will be attached to Backtrace report in the report generated on Windows machine.
• Attach Unity Player.log: Add Unity player log file to Backtrace report. NOTE: This feature is available only on desktop - Windows/MacOS/Linux.
• Attach screenshot: Generate and attach screenshot of frame as exception occurs.
• Auto Send Mode: When toggled on, the database will send automatically reports to Backtrace server based on the Retry Settings below. When toggled off, the developer will need to use the Flush method to attempt to send and clear. Recommend that this is toggled on.
• Maximum number of records: This is one of two limits you can impose for controlling the growth of the offline store. This setting is the maximum number of stored reports in database. If value is equal to zero, then limit not exists, When the limit is reached, the database will remove the oldest entries.
• Maximum database size: This is the second limit you can impose for controlling the growth of the offline store. This setting is the maximum database size in MB. If value is equal to zero, then size is unlimited, When the limit is reached, the database will remove the oldest entries.
• Retry interval: If the database is unable to send its record, this setting specifies how many seconds the library should wait between retries.
• Maximum retries: If the database is unable to send its record, this setting specifies the maximum number of retries before the system gives up.
• Retry order: This specifies in which order records are sent to the Backtrace server.

Android Specific information

The backtrace-unity library includes support for capturing Android NDK crashes and additional Android Native information, from underlying Android OS (Memory and process related), JNI, and NDK layers.

Native process and memory related information

system.memory usage related information including memfree, swapfree, and vmalloc.used is now available. Additional VM details and voluntary / nonvountary ctxt switches are included.

ANR

When configuring the backtrace-unity client for an Android deployment, programmers will have a toggle available in backtrace-unity GUI in the Unity Editor to enable or disable ANR reports. This will use the default of 5 seconds.

Symbols upload

Unity allows developer to generate symbols archive called symbols.zip in the il2cpp build pipeline in the root directory of your game. In this archive you can find generated symbols for your game libraries. When your game crashes due to a native exception, your stack trace will contain only memory addresses instead of function name. Symbols from symbols.zip archive allows Backtrace to match function address to function name in your source code.

To generate symbols.zip archive make sure:

• you selected il2cpp build,
• you checked Create symbols.zip in the Build settings window

To upload symbols to Backtrace, you need to rename symbols generated by Unity end simply with a .so extension. By default, symbol files within the .zip will end with extension .sym.so. or .dbg.so Backtrace will only match symbols to files based on the ending with .so extension. Please ensure all files have a single .so extention before uploading the zip. To upload symbols please go to your project settings, to the Upload an archive tab under Symbols section.

Backtrace offers to upload symbols automatically from Unity Editor to your Backtrace instance. Backtrace symbols upload pipeline will be triggered after successfull build of il2cpp Android game and when Symbols upload token is available in Backtrace Client options. After successfull build, upload pipeline will confirm symbols upload.

iOS Specific information

The backtrace-unity library includes support for capturing native iOS crashes as well as iOS native memory and process information from underlying iOS layer.

Native process and memory related information

system and vm usage related information including system.memory.free, system.memory.used, system.memory.total, system.memory.active, system.memory.inactive, system.memory.wired are avaialble.

Native Crashes

When configuring the backtrace-unity client for an iOS deployment in the Unity Editor, programmers will have a toggle to enable or disable Capture native crashes. If this is enabled, the backtrace-unity client will ensure the crash report is generated, stored locally, and uploaded upon next game start. Unity crash reporter might prevent Backtrace Crash reporte from sending crashes to Backtrace. To be sure Backtrace is able to collect and send data please set "Enable CrashReport API" to false.

Debug Symbol upload

When building your iOS game in Xcode, you must make sure you configure the build settings to generate "DWARF with dSYM files for any build that you want to debug with Backtrace (By default, it may only generate DWARF). In the example below, DWARF with dSYM files is enabled in the Project Build Settings for each Target.

This change will generate dSYM files every time you build your game in Xcode. You can find the files in the ...\Build\Products\<the folder representing your build>. Within there will be dSYM files that you should compress into a .zip file and submit to Backtrace for use during symbolication.

To learn more about how to submit those symbol files to Backtrace, please see the Project Settings / Symbols. You can manage submission tokens, upload via the UI, or configure external Symbol Servers to connect and discover required symbols. Please review additional Symbol documentaion at https://support.backtrace.io/hc/en-us/articles/360040517071-Symbolication-Overview

API Overview

You can further configure your game to submit crashes by making further changes in the C# code for your game.

Basic configuration

If you setup Backtrace client and Backtrace database configuration you can retrieve database and client instances by using GameObject. When you retrieve client instance you can start sending reports from try/catch block in your game!

 //Read from manager BacktraceClient instance
var backtraceClient = GameObject.Find("manager name").GetComponent<BacktraceClient>();

//Set custom client attribute
backtraceClient["attribute"] = "attribute value";

 //Read from manager BacktraceClient instance
var database = GameObject.Find("manager name").GetComponent<BacktraceDatabase>();


try{
    //throw exception here
}
catch(Exception exception){
    var report = new BacktraceReport(exception);
    backtraceClient.Send(report);
}

If you would like to change Backtrace client/database options, we recommend to change these values on the Unity UI via Backtrace Configuration file. However, if you would like to change these values dynamically, please use method Refresh to apply new configuration changes.

For example:

//Read from manager BacktraceClient instance
var backtraceClient = GameObject.Find("manager name").GetComponent<BacktraceClient>();
//Set custom client attribute
backtraceClient["attribute"] = "attribute value";
//Change configuration value
backtraceClient.Configuration.DeduplicationStrategy = deduplicationStrategy;
//Refresh configuraiton
backtraceClient.Refresh();

Sending an error report

BacktraceClient.Send method will send an error report to the Backtrace endpoint specified. There Send method is overloaded, see examples below:

Using BacktraceReport

The BacktraceReport class represents a single error report. (Optional) You can also submit custom attributes using the attributes parameter, or attach files by supplying an array of file paths in the attachmentPaths parameter.

try
{
  //throw exception here
}
catch (Exception exception)
{
    var report = new BacktraceReport(
        exception: exception,
        attributes: new Dictionary<string, string>() { { "key", "value" } },
        attachmentPaths: new List<string>() { @"file_path_1", @"file_path_2" }
    );
    backtraceClient.Send(report);
}

Notes:

• if you setup BacktraceClient with BacktraceDatabase and your application is offline or you pass invalid credentials to Backtrace server, reports will be stored in database directory path,
• BacktraceReport allows you to change default Fingerprint generation algorithm. You can use Fingerprint property if you want to change Fingerprint value. Keep in mind - Fingerprint should be valid sha256 string. By setting Fingerprint you are instructing the client reporting library to only write a single report for the exception as it is encountered, and maintain a counter for every additional time it is encountered, instead of creating a new report. This will allow better control over the volume of reports being generated and sent to Backtrace. The counter is reset when the offline database is cleared (usually when the reports are sent to the server). A new single report will be created the next time the error is encountered.
• BacktraceReport allows you to change grouping strategy in Backtrace server. If you want to change how algorithm group your reports in Backtrace server please override Factor property.

If you want to use Fingerprint and Factor property you have to override default property values. See example below to check how to use these properties:

try
{
  //throw exception here
}
catch (Exception exception)
{
    var report = new BacktraceReport(...){
        Fingerprint = "sha256 string",
        Factor = exception.GetType().Name
    };
    ....
}

Attaching custom event handlers

BacktraceClient allows you to attach your custom event handlers. For example, you can trigger actions before the Send method:

 //Add your own handler to client API

backtraceClient.BeforeSend =
    (Model.BacktraceData model) =>
    {
        var data = model;
        //do something with data for example:
        data.Attributes.Add("eventAttribute", "EventAttributeValue");
        if(data.Classifier == null || !data.Classifier.Any())
        {
            data.Attachments.Add("path to attachment");
        }

        return data;
    };

BacktraceClient currently supports the following events:

• BeforeSend
• OnClientReportLimitReached
• OnServerResponse
• OnServerError

Reporting unhandled application exceptions

BacktraceClient supports reporting of unhandled application exceptions not captured by your try-catch blocks. To enable reporting of unhandled exceptions please use Backtrace configuration UI available in the Unity IDE.

Filtering a report

Report filtering is enabled by using the Filter reports option in the user interface or for more advanced use-cases, the SkipReport delegate available in the BacktraceClient.

Sample code:

  // Return true to ignore a report, return false to handle the report
  // and generate one for the error.
  BacktraceClient.SkipReport = (ReportFilterType type, Exception e, string msg) =>
  {
    // ReportFilterType is one of None, Message, Exception,
    // UnhandledException or Hang. It is also possible to
    // to filter based on the exception and exception message.

    // Report hangs and crashes only.
    return type != ReportFilterType.Hang && type != ReportFilterType.UnhandledException;
  };

For example, to only get error reporting for hangs or crashes then only return false for Hang or UnhandledException or set the corresponding options in the user interface as shown below.

Flush database

When your application starts, database can send stored offline reports. If you want to do make it manually you can use Flush method that allows you to send report to server and then remove it from hard drive. If Send method fails, database will no longer store data.

backtraceDatabase.Flush();

Send database

This method will try to send all objects from the database respecting the client side deduplication and retry setting. This can be used as an alternative to the Flush method which will try to send all objects from the database ignoring any client side deduplication and retry settings.

backtraceDatabase.Send();

Clearing database

You can clear all data from database without sending it to server by using Clear method. BacktraceDatabase will remove all files and won't send it to server.

backtraceDatabase.Clear();

Client side Deduplication

Backtrace unity integration allows you to aggregate the same reports and send only one message to Backtrace Api. As a developer you can choose deduplication options. Please use DeduplicationStrategy enum to setup possible deduplication rules in Unity UI:

Deduplication strategy types:

• Ignore - ignore deduplication strategy,
• Default - deduplication strategy will only use current strack trace to find duplicated reports,
• Classifier - deduplication strategy will use stack trace and exception type to find duplicated reports,
• Message - deduplication strategy will use stack trace and exception message to find duplicated reports,

Notes:

• When you aggregate reports via Backtrace C# library, BacktraceDatabase will increase number of reports in BacktraceDatabaseRecord counter property.
• Deduplication algorithm will include BacktraceReport Fingerprint and Factor properties. Fingerprint property will overwrite deduplication algorithm result. Factor property will change hash generated by deduplication algorithm.
• If Backtrace unity integration combine multiple reports and user will close a game before plugin will send data to Backtrace, you will lose coutner information.
• BacktraceDatabase methods allows you to use aggregated diagnostic data together. You can check Hash property of BacktraceDatabaseRecord to check generated hash for diagnostic data and Counter to check how much the same records we detect.
• BacktraceDatabase Count method will return number of all records stored in database (included deduplicated records),
• BacktarceDatabase Delete method will remove record (with multiple deduplicated records) at the same time.

Architecture description

BacktraceReport

BacktraceReport is a class that describe a single error report.

BacktraceClient

BacktraceClient is a class that allows you to send BacktraceReport to Backtrace server by using BacktraceApi. This class sets up connection to the Backtrace endpoint and manages error reporting behavior (for example, saving minidump files on your local hard drive and limiting the number of error reports per minute). BacktraceClient inherits from Mono behavior.

BacktraceClient requires from a Backtrace configuration window

• Sever URL - URL to Backtrace server,
• Token - token to Backtrace project,
• ReportPerMin - A cap on the number of reports that can be sent per minute. If ReportPerMin is equal to zero then there is no cap.
• HandleUnhandledExceptions - flag that allows BacktraceClient handling unhandled exception by default.

BacktraceData

BacktraceData is a serializable class that holds the data to create a diagnostic JSON to be sent to the Backtrace endpoint via BacktraceApi. You can add additional pre-processors for BacktraceData by attaching an event handler to the BacktraceClient.BeforeSend event. BacktraceData require BacktraceReport and BacktraceClient client attributes.

BacktraceApi

BacktraceApi is a class that sends diagnostic JSON to the Backtrace endpoint. BacktraceApi is instantiated when the BacktraceClient awake method is called. BacktraceApi can asynchronous reports to the Backtrace endpoint.

BacktraceDatabase

BacktraceDatabase is a class that stores error report data in your local hard drive. BacktraceDatabase stores error reports that were not sent successfully due to network outage or server unavailability. BacktraceDatabase periodically tries to resend reports cached in the database. In BacktraceDatabaseSettings you can set the maximum number of entries (Maximum retries) to be stored in the database. The database will retry sending stored reports every Retry interval seconds up to Retry limit times, both customizable in the Backtrace database configuration.

Backtrace database has the following properties:

• Database path - the local directory path where BacktraceDatabase stores error report data when reports fail to send,
• MaxRecordCount - Maximum number of stored reports in Database. If value is equal to 0, then there is no limit.
• MaxDatabaseSize - Maximum database size in MB. If value is equal to 0, there is no limit.
• AutoSendMode - if the value is true, BacktraceDatabase will automatically try to resend stored reports. Default is false.
• RetryBehavior - - RetryBehavior.ByInterval - Default. BacktraceDatabase will try to resend the reports every time interval specified by RetryInterval. - RetryBehavior.NoRetry - Will not attempt to resend reports
• RetryInterval - the time interval between retries, in seconds.
• RetryLimit - the maximum number of times BacktraceDatabase will attempt to resend error report before removing it from the database.

If you want to clear your database or remove all reports after send method you can use Clear and Flush.

ReportWatcher

ReportWatcher is a class that validate send requests to the Backtrace endpoint. If reportPerMin is set in the BacktraceClient constructor call, ReportWatcher will drop error reports that go over the limit. BacktraceClient check rate limit before BacktraceApi generate diagnostic json.

Investigating an Error in Backtrace

Once errors are being reported to your Backtrace instance, you should see them in your Triage and Web Debugger view. See below for a screenshot of the Triage view with some Unity exceptions reported.

The developer who is debugging the error may find it useful to view more details of Exception. They choose the 'View Latest Trace' action to see more details in the Backtrace Web Debugger. Below we can see a list of all attributes submitted with a report. (Note the yield signs are just an indicator that this value is not indexed in Backtrace). We can also see the call stack and details of the selected frame.

Below we see more details above the Environment Variables from the Web Debugger to further assist with investigation.