dotnet - add locking since the simulator seems to run a lot in parallel

change the port to match what the simulator uses by default

add serilog as part of debugging

dotnet/SafelyYou/Devices.cs

@@ -16,6 +16,7 @@ public sealed class KnownDevices
 
 public sealed class DeviceHeartBeatHistory
 {
+    private readonly Lock _lock = new();
 
     public enum AddResult { Added, OutOfSequence }
 
@@ -25,6 +26,8 @@ public sealed class DeviceHeartBeatHistory
 
 
     public AddResult Add(DateTimeOffset sentAt)
+    {
+        lock (_lock)
         {
             // Reject heartbeats that arrive before the latest registered time.
             // Gaps are fine: uptime can be derived from first, last, and count.
@@ -44,19 +47,24 @@ public sealed class DeviceHeartBeatHistory
             NumberOfHeartBeats++;
             return AddResult.Added;
         }
+    }
 }
 
 public sealed class HeartBeatHistories
 {
     private readonly ConcurrentDictionary<DeviceId, DeviceHeartBeatHistory> _histories = new();
+    private readonly Lock _lock = new ();
 
     public DeviceHeartBeatHistory.AddResult Add(DeviceId deviceId, DateTimeOffset sentAt)
     {
         if (!_histories.TryGetValue(deviceId, out var history))
+        {
+            lock (_lock)
             {
                 history = new();
                 _histories[deviceId] = history;
             }
+        }
 
         return history.Add(sentAt);
     }

dotnet/SafelyYou/Program.cs

@@ -1,15 +1,23 @@
 using SafelyYou;
 using SafelyYou.Api;
+using Serilog;
 
 var builder = WebApplication.CreateBuilder(args);
 
 // Add services to the container.
 // Learn more about configuring OpenAPI at https://aka.ms/aspnet/openapi
+
+Log.Logger = new LoggerConfiguration()
+    .WriteTo.Console()
+    .CreateLogger();
+
+builder.Services.AddSerilog();
 builder.Services.AddOpenApi();
 
 builder.Services.AddSingleton<KnownDevices>(_ =>
 {
-    var deviceIds = File.ReadAllLines("/devices.csv").Skip(1).Select(id => new DeviceId(id)).ToHashSet();
+    var deviceIds = File.ReadAllLines("./devices.csv").Skip(1).Select(id => new DeviceId(id)).ToHashSet();
+    Log.Logger.Information("@deviceIds", deviceIds);
     return new KnownDevices(deviceIds);
 });
 
@@ -17,6 +25,7 @@ builder.Services.AddSingleton<HeartBeatHistories>();
 builder.Services.AddSingleton<UploadTimes>();
 
 var app = builder.Build();
+app.UseSerilogRequestLogging();
 
 // Configure the HTTP request pipeline.
 if (app.Environment.IsDevelopment())
@@ -24,12 +33,12 @@ if (app.Environment.IsDevelopment())
     app.MapOpenApi();
 }
 
-app.UseHttpsRedirection();
+//app.UseHttpsRedirection();
 
 // heartbeat history
 // upload stats
 
-app.MapPost("/devices/{deviceId}/heartbeat", (string deviceId, HeartbeatRequest request,
+app.MapPost("api/v1/devices/{deviceId}/heartbeat", (string deviceId, HeartbeatRequest request,
     KnownDevices knownDevices, HeartBeatHistories histories) =>
 {
     var device = new DeviceId(deviceId);
@@ -49,7 +58,7 @@ app.MapPost("/devices/{deviceId}/heartbeat", (string deviceId, HeartbeatRequest
     };
 });
 
-app.MapPost("/devices/{deviceId}/stats", (string deviceId, UploadStatsRequest request, KnownDevices knownDevices, UploadTimes uploadTimes) =>
+app.MapPost("api/v1/devices/{deviceId}/stats", (string deviceId, UploadStatsRequest request, KnownDevices knownDevices, UploadTimes uploadTimes) =>
 {
     var device = new DeviceId(deviceId);
     if (!knownDevices.Contains(device))
@@ -62,9 +71,10 @@ app.MapPost("/devices/{deviceId}/stats", (string deviceId, UploadStatsRequest re
     return Results.NoContent();
     
     // not sure where the 500 would go here beyond doing a try/catch
+    // note: sent_at isn't used here since the data is a short-cut of aggregation, so it's dropped.
 });
 
-app.MapGet("/devices/{deviceId}/stats", (string deviceId, KnownDevices knownDevices, HeartBeatHistories histories, UploadTimes uploadTimes) =>
+app.MapGet("api/v1/devices/{deviceId}/stats", (string deviceId, KnownDevices knownDevices, HeartBeatHistories histories, UploadTimes uploadTimes) =>
 {
     var device = new DeviceId(deviceId);
     if (!knownDevices.Contains(device))
@@ -73,7 +83,7 @@ app.MapGet("/devices/{deviceId}/stats", (string deviceId, KnownDevices knownDevi
     }
 
     var averageUploadTimeNanos = uploadTimes.AverageUploadTimeNanoseconds(device);
-    var timeSpanText = TimeSpan.FromTicks((long)(averageUploadTimeNanos / 100)).ToString(@"m\ms\s"); // loses accuracy on the Go nanos for this text conversion
+    var timeSpanText = FormatAsGoDuration(averageUploadTimeNanos);
     var uptime = histories.Uptime(device);
     
     return Results.Ok(new GetDeviceStatsResponse(timeSpanText, uptime));
@@ -84,3 +94,63 @@ app.MapGet("/devices/{deviceId}/stats", (string deviceId, KnownDevices knownDevi
 
 app.Run();
 
+// Matches Go's time.Duration.String() (e.g. "3m17.331667813s").
+static string FormatAsGoDuration(System.Numerics.BigInteger nanos)
+{
+    if (nanos <= 0) return "0s";
+
+    var u = (ulong)nanos;
+    Span<char> buf = stackalloc char[32];
+    var w = buf.Length;
+
+    // Fractional seconds from nanoseconds, omitting trailing zeros — same as Go fmtFrac(..., 9).
+    var frac = u % 1_000_000_000UL;
+    u /= 1_000_000_000UL;
+
+    buf[--w] = 's';
+    if (frac != 0)
+    {
+        var print = false;
+        for (var i = 0; i < 9; i++)
+        {
+            var digit = frac % 10;
+            frac /= 10;
+            if (digit != 0) print = true;
+            if (print) buf[--w] = (char)('0' + digit);
+        }
+        buf[--w] = '.';
+    }
+
+    var secs = u % 60;
+    u /= 60;
+    do
+    {
+        buf[--w] = (char)('0' + secs % 10);
+        secs /= 10;
+    } while (secs > 0);
+
+    if (u > 0)
+    {
+        buf[--w] = 'm';
+        var mins = u % 60;
+        u /= 60;
+        do
+        {
+            buf[--w] = (char)('0' + mins % 10);
+            mins /= 10;
+        } while (mins > 0);
+
+        if (u > 0)
+        {
+            buf[--w] = 'h';
+            do
+            {
+                buf[--w] = (char)('0' + u % 10);
+                u /= 10;
+            } while (u > 0);
+        }
+    }
+
+    return new string(buf[w..]);
+}
+

dotnet/SafelyYou/Properties/launchSettings.json

@@ -5,7 +5,7 @@
       "commandName": "Project",
       "dotnetRunMessages": true,
       "launchBrowser": false,
-      "applicationUrl": "http://localhost:5213",
+      "applicationUrl": "http://localhost:6733",
       "environmentVariables": {
         "ASPNETCORE_ENVIRONMENT": "Development"
       }
@@ -14,7 +14,7 @@
       "commandName": "Project",
       "dotnetRunMessages": true,
       "launchBrowser": false,
-      "applicationUrl": "https://localhost:7175;http://localhost:5213",
+      "applicationUrl": "https://localhost:7175;http://localhost:6734",
       "environmentVariables": {
         "ASPNETCORE_ENVIRONMENT": "Development"
       }

dotnet/SafelyYou/SafelyYou.csproj

@@ -8,6 +8,9 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="10.0.7" />
+    <PackageReference Include="Serilog" Version="4.4.0" />
+    <PackageReference Include="Serilog.AspNetCore" Version="10.0.0" />
+    <PackageReference Include="Serilog.Sinks.Console" Version="6.1.1" />
   </ItemGroup>
 
   <ItemGroup>

dotnet/SafelyYou/SafelyYou.http

@@ -1,6 +1,9 @@
-@SafelyYou_HostAddress = http://localhost:5213
+@SafelyYou_HostAddress = http://localhost:6733/api
 
-GET {{SafelyYou_HostAddress}}/weatherforecast/
+POST {{SafelyYou_HostAddress}}/devices/38-4e-73-e0-33-59/heartbeat
 Accept: application/json
 
+{
+  "sent_at": "2026-08-06T16:51:22.861Z"
+}
 ###

dotnet/SafelyYou/UploadTimes.cs

@@ -5,9 +5,12 @@ namespace SafelyYou;
 
 public sealed class UploadTimes
 {
+    private readonly Lock _lock = new();
     private readonly ConcurrentDictionary<DeviceId, (BigInteger TotalUploadTime, int UploadCounts)> _uploadHistories = new();
 
     public void Add(DeviceId deviceId, BigInteger uploadTimeNanos)
+    {
+        lock (_lock)
         {
             if (!_uploadHistories.TryGetValue(deviceId, out var history))
             {
@@ -16,6 +19,7 @@ public sealed class UploadTimes
 
             _uploadHistories[deviceId] = (history.TotalUploadTime + uploadTimeNanos, history.UploadCounts + 1);
         }
+    }
 
     public BigInteger AverageUploadTimeNanoseconds(DeviceId deviceId)
     {