Add ADB device tracking (host:track-devices) for real-time device monitoring by rmarinho · Pull Request #327 · dotnet/android-tools

rmarinho · 2026-04-08T16:40:30Z

Summary

Add support for real-time device connection/disconnection monitoring via the ADB daemon socket protocol (\host:track-devices-l).

Changes

Added \AdbDeviceTracker\ class implementing \IDisposable\
Socket connection to \localhost:5037\ (ADB daemon)
Sends \host:track-devices-l\ command and reads length-prefixed device list updates
Callback-based \StartAsync()\ with \CancellationToken\ support
\CurrentDevices\ snapshot property for current device state
Auto-reconnect with exponential backoff (500ms → 16s) on connection drops
Reuses existing \AdbRunner.ParseAdbDevicesOutput()\ for parsing
11 unit tests covering protocol parsing, lifecycle, and edge cases
Updated \PublicAPI.Unshipped.txt\ for both
et10.0\ and
etstandard2.0\

API

\\csharp
public sealed class AdbDeviceTracker : IDisposable
{
public AdbDeviceTracker(string? adbPath = null, int port = 5037, ...);
public IReadOnlyList CurrentDevices { get; }
public Task StartAsync(Action<IReadOnlyList> onDevicesChanged, CancellationToken cancellationToken = default);
public void Dispose();
}
\\

Closes #323

Add AdbDeviceTracker class for real-time device connection monitoring via the ADB daemon socket protocol. Connects to localhost:5037, sends host:track-devices-l, and pushes device list updates through a callback. Features: - Auto-reconnect with exponential backoff (500ms to 16s) - Callback-based StartAsync() with CancellationToken support - CurrentDevices snapshot property - IDisposable lifecycle management - Reuses AdbRunner.ParseAdbDevicesOutput() for parsing Includes 11 unit tests covering protocol parsing, edge cases, and lifecycle management. PublicAPI entries for both net10.0 and netstandard2.0. Closes #323 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Adds a new AdbDeviceTracker public API to Xamarin.Android.Tools.AndroidSdk to monitor ADB device connect/disconnect events in real time using the host:track-devices-l daemon socket protocol.

Changes:

Introduces AdbDeviceTracker with reconnect/backoff, snapshot state (CurrentDevices), and callback-driven tracking via StartAsync.
Adds unit tests validating lifecycle guards and length-prefixed protocol parsing behavior.
Updates PublicAPI unshipped files for netstandard2.0 and net10.0.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
tests/Xamarin.Android.Tools.AndroidSdk-Tests/AdbDeviceTrackerTests.cs	Adds tests for tracker lifecycle and length-prefixed message parsing.
src/Xamarin.Android.Tools.AndroidSdk/Runners/AdbDeviceTracker.cs	Implements TCP-based `host:track-devices-l` tracking loop with reconnect/backoff and parsing.
src/Xamarin.Android.Tools.AndroidSdk/PublicAPI/netstandard2.0/PublicAPI.Unshipped.txt	Registers the new public API surface for netstandard2.0.
src/Xamarin.Android.Tools.AndroidSdk/PublicAPI/net10.0/PublicAPI.Unshipped.txt	Registers the new public API surface for net10.0.

Copilot · 2026-04-08T16:44:39Z

src/Xamarin.Android.Tools.AndroidSdk/Runners/AdbDeviceTracker.cs

+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using System.Linq;


using System.Linq; is not used in this file and will trigger CS8019 (and can fail Release builds when warnings are treated as errors). Remove the unnecessary using.

Suggested change

using System.Linq;

Copilot · 2026-04-08T16:44:39Z

src/Xamarin.Android.Tools.AndroidSdk/Runners/AdbDeviceTracker.cs

+	readonly int port;
+	readonly Action<TraceLevel, string> logger;
+	readonly string? adbPath;
+	readonly IDictionary<string, string>? environmentVariables;
+	IReadOnlyList<AdbDeviceInfo> currentDevices = Array.Empty<AdbDeviceInfo> ();
+	CancellationTokenSource? trackingCts;
+	bool disposed;
+
+	/// <summary>
+	/// Creates a new AdbDeviceTracker.
+	/// </summary>
+	/// <param name="adbPath">Optional path to the adb executable for starting the server if needed.</param>
+	/// <param name="port">ADB daemon port (default 5037).</param>
+	/// <param name="environmentVariables">Optional environment variables for adb processes.</param>
+	/// <param name="logger">Optional logger callback.</param>
+	public AdbDeviceTracker (string? adbPath = null, int port = 5037,
+		IDictionary<string, string>? environmentVariables = null,
+		Action<TraceLevel, string>? logger = null)
+	{
+		if (port <= 0 || port > 65535)
+			throw new ArgumentOutOfRangeException (nameof (port), "Port must be between 1 and 65535.");
+		this.adbPath = adbPath;
+		this.port = port;
+		this.environmentVariables = environmentVariables;
+		this.logger = logger ?? RunnerDefaults.NullLogger;


adbPath and environmentVariables are assigned but never used, which will raise CS0414 (and can fail Release builds when warnings are treated as errors). Either implement the advertised behavior (e.g., start/ensure the ADB server using adbPath and pass environmentVariables to that process) or remove these fields/ctor parameters to avoid a misleading public API surface.

Copilot · 2026-04-08T16:44:40Z

src/Xamarin.Android.Tools.AndroidSdk/Runners/AdbDeviceTracker.cs

+		trackingCts = CancellationTokenSource.CreateLinkedTokenSource (cancellationToken);
+		var token = trackingCts.Token;
+		var backoffMs = InitialBackoffMs;
+
+		while (!token.IsCancellationRequested) {
+			try {
+				await TrackDevicesAsync (onDevicesChanged, token).ConfigureAwait (false);
+			} catch (OperationCanceledException) when (token.IsCancellationRequested) {
+				break;
+			} catch (Exception ex) {
+				logger.Invoke (TraceLevel.Warning, $"ADB tracking connection lost: {ex.Message}. Reconnecting in {backoffMs}ms...");
+				try {
+					await Task.Delay (backoffMs, token).ConfigureAwait (false);
+				} catch (OperationCanceledException) {
+					break;
+				}
+				backoffMs = Math.Min (backoffMs * 2, MaxBackoffMs);
+				continue;
+			}
+			// Reset backoff on clean connection
+			backoffMs = InitialBackoffMs;


StartAsync creates and stores a linked CancellationTokenSource but never disposes it when StartAsync completes (only on Dispose()), and repeated StartAsync calls will overwrite trackingCts. Consider using a local CTS with a try/finally to dispose it, and guarding against multiple concurrent starts (throw or no-op) to avoid leaks/races.

Suggested change

trackingCts = CancellationTokenSource.CreateLinkedTokenSource (cancellationToken);

var token = trackingCts.Token;

var backoffMs = InitialBackoffMs;

while (!token.IsCancellationRequested) {

try {

await TrackDevicesAsync (onDevicesChanged, token).ConfigureAwait (false);

} catch (OperationCanceledException) when (token.IsCancellationRequested) {

break;

} catch (Exception ex) {

logger.Invoke (TraceLevel.Warning, $"ADB tracking connection lost: {ex.Message}. Reconnecting in {backoffMs}ms...");

try {

await Task.Delay (backoffMs, token).ConfigureAwait (false);

} catch (OperationCanceledException) {

break;

}

backoffMs = Math.Min (backoffMs * 2, MaxBackoffMs);

continue;

}

// Reset backoff on clean connection

backoffMs = InitialBackoffMs;

var linkedCts = CancellationTokenSource.CreateLinkedTokenSource (cancellationToken);

if (Interlocked.CompareExchange (ref trackingCts, linkedCts, null) != null) {

linkedCts.Dispose ();

throw new InvalidOperationException ("Device tracking has already been started.");

}

try {

var token = linkedCts.Token;

var backoffMs = InitialBackoffMs;

while (!token.IsCancellationRequested) {

try {

await TrackDevicesAsync (onDevicesChanged, token).ConfigureAwait (false);

} catch (OperationCanceledException) when (token.IsCancellationRequested) {

break;

} catch (Exception ex) {

logger.Invoke (TraceLevel.Warning, $"ADB tracking connection lost: {ex.Message}. Reconnecting in {backoffMs}ms...");

try {

await Task.Delay (backoffMs, token).ConfigureAwait (false);

} catch (OperationCanceledException) {

break;

}

backoffMs = Math.Min (backoffMs * 2, MaxBackoffMs);

continue;

}

// Reset backoff on clean connection

backoffMs = InitialBackoffMs;

}

} finally {

Interlocked.CompareExchange (ref trackingCts, null, linkedCts);

linkedCts.Dispose ();

rmarinho requested review from jonathanpeppers and simonrozsival as code owners April 8, 2026 16:40

Copilot AI review requested due to automatic review settings April 8, 2026 16:40

Copilot started reviewing on behalf of rmarinho April 8, 2026 16:41 View session

Copilot AI reviewed Apr 8, 2026

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Add ADB device tracking (host:track-devices) for real-time device monitoring#327

Add ADB device tracking (host:track-devices) for real-time device monitoring#327
rmarinho wants to merge 1 commit intomainfrom
features/323-adb-device-tracker

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rmarinho commented Apr 8, 2026

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