feat: Add breadcrumb for lowMemory events (#2406)

Author: bitsandfoxes

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Features
 
+- The SDK automatically subscribes to and leaves breadcrumbs for `Application.lowMemory` events ([#2406](https://github.com/getsentry/sentry-unity/pull/2406))
 - The SDK now also reports the currently allocated memory when reporting an event or transaction. ([#2398](https://github.com/getsentry/sentry-unity/pull/2398))
 - The SDK defaults `EnvironmentUser` to sensible values based on the current platform. This is still guarded by the `SendDefaultPII` flag. ([#2402](https://github.com/getsentry/sentry-unity/pull/2402))
 

src/Sentry.Unity/Integrations/IApplication.cs

@@ -7,6 +7,7 @@ namespace Sentry.Unity.Integrations;
 internal interface IApplication
 {
     event Application.LogCallback LogMessageReceived;
+    event Action LowMemory;
     event Action Quitting;
     string ActiveSceneName { get; }
     bool IsEditor { get; }
@@ -28,10 +29,12 @@ public sealed class ApplicationAdapter : IApplication
     private ApplicationAdapter()
     {
         Application.logMessageReceivedThreaded += OnLogMessageReceived;
+        Application.lowMemory += OnLowMemory;
         Application.quitting += OnQuitting;
     }
 
     public event Application.LogCallback? LogMessageReceived;
+    public event Action? LowMemory;
 
     public event Action? Quitting;
 
@@ -54,6 +57,9 @@ private ApplicationAdapter()
     private void OnLogMessageReceived(string condition, string stackTrace, LogType type)
         => LogMessageReceived?.Invoke(condition, stackTrace, type);
 
+    private void OnLowMemory()
+        => LowMemory?.Invoke();
+
     private void OnQuitting()
         => Quitting?.Invoke();
 }

src/Sentry.Unity/Integrations/LowMemoryIntegration.cs

@@ -0,0 +1,37 @@
+using System.Collections.Generic;
+using Sentry.Integrations;
+
+namespace Sentry.Unity.Integrations;
+
+internal class LowMemoryIntegration : ISdkIntegration
+{
+    private static readonly Dictionary<string, string> lowMemoryData = new() { { "action", "LOW_MEMORY" } };
+
+    private IHub _hub = null!;
+    private IApplication _application;
+
+    public LowMemoryIntegration(IApplication? application = null)
+    {
+        _application = application ?? ApplicationAdapter.Instance;
+    }
+
+    public void Register(IHub hub, SentryOptions options)
+    {
+        _hub = hub;
+
+        _application.LowMemory += () =>
+        {
+            if (!_hub.IsEnabled)
+            {
+                return;
+            }
+
+            hub.AddBreadcrumb(new Breadcrumb(
+                message: "Low memory",
+                type: "system",
+                data: lowMemoryData,
+                category: "device.event",
+                level: BreadcrumbLevel.Warning));
+        };
+    }
+}

src/Sentry.Unity/SentryUnityOptions.cs

@@ -365,6 +365,7 @@ internal SentryUnityOptions(IApplication? application = null,
         AddIntegration(new SceneManagerTracingIntegration());
         AddIntegration(new LifeCycleIntegration(behaviour));
         AddIntegration(new TraceGenerationIntegration(behaviour));
+        AddIntegration(new LowMemoryIntegration());
 
         AddExceptionFilter(new UnityBadGatewayExceptionFilter());
         AddExceptionFilter(new UnityWebExceptionFilter());

test/Sentry.Unity.Tests/LowMemoryIntegrationTests.cs

@@ -0,0 +1,72 @@
+using System.Linq;
+using NUnit.Framework;
+using Sentry.Unity.Integrations;
+using Sentry.Unity.Tests.Stubs;
+
+namespace Sentry.Unity.Tests;
+
+public class LowMemoryIntegrationTests
+{
+    private class Fixture
+    {
+        public TestApplication Application { get; set; } = new();
+        public TestHub Hub { get; set; } = new();
+        public SentryUnityOptions Options { get; set; } = new();
+
+        public LowMemoryIntegration GetSut() => new(Application);
+    }
+
+    private Fixture _fixture = null!;
+
+    [SetUp]
+    public void SetUp()
+    {
+        _fixture = new Fixture();
+    }
+
+    [Test]
+    public void LowMemory_DisabledHub_NoBreadcrumbAdded()
+    {
+        _fixture.Hub = new TestHub(false);
+        var sut = _fixture.GetSut();
+
+        sut.Register(_fixture.Hub, _fixture.Options);
+        _fixture.Application.OnLowMemory();
+
+        Assert.Zero(_fixture.Hub.ConfigureScopeCalls.Count);
+    }
+
+    [Test]
+    public void LowMemory_EnabledHub_BreadcrumbAdded()
+    {
+        var sut = _fixture.GetSut();
+
+        sut.Register(_fixture.Hub, _fixture.Options);
+        _fixture.Application.OnLowMemory();
+
+        var configureScope = _fixture.Hub.ConfigureScopeCalls.Single();
+        var scope = new Scope(_fixture.Options);
+        configureScope(scope);
+        var actualCrumb = scope.Breadcrumbs.Single();
+
+        Assert.AreEqual("Low memory", actualCrumb.Message);
+        Assert.AreEqual("device.event", actualCrumb.Category);
+        Assert.AreEqual("system", actualCrumb.Type);
+        Assert.AreEqual(BreadcrumbLevel.Warning, actualCrumb.Level);
+        Assert.NotNull(actualCrumb.Data);
+        Assert.AreEqual("LOW_MEMORY", actualCrumb.Data?["action"]);
+    }
+
+    [Test]
+    public void LowMemory_MultipleTriggers_MultipleBreadcrumbsAdded()
+    {
+        var sut = _fixture.GetSut();
+
+        sut.Register(_fixture.Hub, _fixture.Options);
+        _fixture.Application.OnLowMemory();
+        _fixture.Application.OnLowMemory();
+        _fixture.Application.OnLowMemory();
+
+        Assert.AreEqual(3, _fixture.Hub.ConfigureScopeCalls.Count);
+    }
+}

test/SharedClasses/TestApplication.cs

@@ -25,6 +25,7 @@ public TestApplication(
     }
 
     public event Application.LogCallback? LogMessageReceived;
+    public event Action? LowMemory;
     public event Action? Quitting;
     public string ActiveSceneName => "TestSceneName";
     public bool IsEditor { get; set; }
@@ -34,8 +35,10 @@ public TestApplication(
     public string UnityVersion { get; set; }
     public string PersistentDataPath { get; set; }
     public RuntimePlatform Platform { get; set; }
-    private void OnQuitting() => Quitting?.Invoke();
 
     private void OnLogMessageReceived(string condition, string stacktrace, LogType type)
         => LogMessageReceived?.Invoke(condition, stacktrace, type);
+
+    public void OnLowMemory() => LowMemory?.Invoke();
+    private void OnQuitting() => Quitting?.Invoke();
 }