Allow configuring grading script concurrency and timeout

JanWichelmann · Jan 1, 2025 · 34a31ea · 34a31ea
1 parent 4a130ba
commit 34a31ea
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Showing 3 changed files with 52 additions and 31 deletions.
diff --git a/src/Ctf4e.LabServer/Controllers/DashboardController.cs b/src/Ctf4e.LabServer/Controllers/DashboardController.cs
@@ -8,16 +8,18 @@
 using Microsoft.AspNetCore.Mvc;
 using Ctf4e.LabServer.Constants;
 using Ctf4e.LabServer.InputModels;
+using Ctf4e.LabServer.Options;
 using Ctf4e.LabServer.Services;
 using Ctf4e.Utilities;
 using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
 
 namespace Ctf4e.LabServer.Controllers;
 
 [Route("")]
 [Route("group")]
 [Authorize]
-public class DashboardController(IStateService stateService, ICtfApiClient ctfApiClient, ILabConfigurationService labConfiguration)
+public class DashboardController(IStateService stateService, ICtfApiClient ctfApiClient, ILabConfigurationService labConfiguration, IOptions<LabOptions> options)
     : ControllerBase<DashboardController>
 {
     protected override MenuItems ActiveMenuItem => MenuItems.Group;
@@ -67,7 +69,9 @@ public async Task<IActionResult> ShowDashboardAsync()
     private async Task<bool> CheckInputAsync(int exerciseId, object input)
     {
         // Don't allow the user to cancel this too early, but also ensure that the application doesn't block too long
-        var cts = new CancellationTokenSource(TimeSpan.FromSeconds(30));
+        // TODO we may want to implement a JS-based grading button that indicates that the grading process is running and does not leave the site in a loading state forever
+        int timeout = options.Value.DockerContainerGradingTimeout ?? 30;
+        var cts = new CancellationTokenSource(TimeSpan.FromSeconds(timeout));
 
         // Get current user
         int userId = GetCurrentUser().UserId;

diff --git a/src/Ctf4e.LabServer/Options/LabOptions.cs b/src/Ctf4e.LabServer/Options/LabOptions.cs
@@ -26,6 +26,10 @@ public class LabOptions
 
     public string DockerContainerGradeScriptPath { get; set; }
 
+    public int? DockerContainerGradingConcurrencyCount { get; set; }
+
+    public int? DockerContainerGradingTimeout { get; set; }
+
     public bool PassAsGroup { get; set; }
 
     public string PageTitle { get; set; }

diff --git a/src/Ctf4e.LabServer/Services/DockerService.cs b/src/Ctf4e.LabServer/Services/DockerService.cs
@@ -24,11 +24,15 @@ public class DockerService : IDockerService, IDisposable
     private readonly IOptions<LabOptions> _options;
 
     private readonly DockerClient _dockerClient;
+    private readonly SemaphoreSlim _gradingLock;
 
     public DockerService(IOptions<LabOptions> options)
     {
         _options = options;
 
+        int concurrencyCount = _options.Value.DockerContainerGradingConcurrencyCount ?? 100;
+        _gradingLock = new SemaphoreSlim(concurrencyCount, concurrencyCount);
+
         // Only initialize this if container support is enabled
         if(_options.Value.EnableDocker)
         {
@@ -73,40 +77,49 @@ public async Task InitUserAsync(int userId, string userName, string password, Ca
 
         if(string.IsNullOrWhiteSpace(gradingScriptPath))
             throw new NotSupportedException("Grading script is not specified.");
-            
-        // Prepare command
-        bool stringInputPresent = input != null;
-        var execCreateResponse = await _dockerClient.Exec.ExecCreateContainerAsync(containerName, new ContainerExecCreateParameters
+
+        // Wait for turn
+        await _gradingLock.WaitAsync(cancellationToken);
+        try
         {
-            AttachStdin = stringInputPresent,
-            AttachStderr = true,
-            AttachStdout = true,
-            Tty = false,
-            Cmd = new List<string>
+            // Prepare command
+            bool stringInputPresent = input != null;
+            var execCreateResponse = await _dockerClient.Exec.ExecCreateContainerAsync(containerName, new ContainerExecCreateParameters
             {
-                gradingScriptPath,
-                userId.ToString(),
-                exerciseId.ToString()
-            },
-            Detach = false
-        }, cancellationToken);
+                AttachStdin = stringInputPresent,
+                AttachStderr = true,
+                AttachStdout = true,
+                Tty = false,
+                Cmd = new List<string>
+                {
+                    gradingScriptPath,
+                    userId.ToString(),
+                    exerciseId.ToString()
+                },
+                Detach = false
+            }, cancellationToken);
 
-        // Run command
-        var execStream = await _dockerClient.Exec.StartAndAttachContainerExecAsync(execCreateResponse.ID, false, cancellationToken);
-
-        // Transmit input, if present
-        if(stringInputPresent)
-        {
-            var inputBytes = Encoding.UTF8.GetBytes(input);
-            await execStream.WriteAsync(inputBytes, 0, inputBytes.Length, cancellationToken);
-            execStream.CloseWrite();
-        }
+            // Run command
+            var execStream = await _dockerClient.Exec.StartAndAttachContainerExecAsync(execCreateResponse.ID, false, cancellationToken);
 
-        // Wait for completion
-        var (stdout, stderr) = await execStream.ReadOutputToEndAsync(cancellationToken);
+            // Transmit input, if present
+            if(stringInputPresent)
+            {
+                var inputBytes = Encoding.UTF8.GetBytes(input);
+                await execStream.WriteAsync(inputBytes, 0, inputBytes.Length, cancellationToken);
+                execStream.CloseWrite();
+            }
+
+            // Wait for completion
+            var (stdout, stderr) = await execStream.ReadOutputToEndAsync(cancellationToken);
 
-        // Passed?
-        return (stdout.Trim() == "1", stderr);
+            // Passed?
+            return (stdout.Trim() == "1", stderr);
+        }
+        finally
+        {
+            _gradingLock.Release();
+        }
     }
 
     public void Dispose()