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ScriptEngine.cs
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ScriptEngine.cs
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using System.Reflection;
using System.Security.Cryptography;
using System.Text;
using BlocklyNet.Core.Model;
using BlocklyNet.Scripting.Parsing;
using BlocklyNet.User;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
namespace BlocklyNet.Scripting.Engine;
/// <summary>
/// The script execution engine. There can be at most one active
/// script at any time.
/// </summary>
/// <param name="context">Execution context of the engine.</param>
/// <param name="_rootProvider">Dependency injection manager.</param>
/// <param name="logger">Logging helper.</param>
/// <param name="parser">Script parser to use.</param>
/// <param name="_groupManager">Helper to manage execution groups.</param>
public partial class ScriptEngine(
IServiceProvider _rootProvider,
IScriptParser parser,
IGroupManager _groupManager,
ILogger<ScriptEngine> logger,
IScriptEngineNotifySink? context = null
) :
IScriptEngine,
IScriptSite,
IDisposable
{
/// <inheritdoc/>
public IScriptEngine Engine => this;
/// <inheritdoc/>
public ILogger Logger => logger;
/// <summary>
/// Synchronize modifying the result.
/// </summary>
protected readonly Semaphore Lock = new(1, 1);
/// <summary>
/// The active script.
/// </summary>
private IScriptInstance? _active;
/// <summary>
/// Set when the one and only script is done.
/// </summary>
private bool _done = false;
/// <inheritdoc/>
public IServiceProvider ServiceProvider => _activeScope?.ServiceProvider ?? _rootProvider;
private IServiceScope? _activeScope;
/// <summary>
/// Manages the cancel process.
/// </summary>
private CancellationTokenSource _cancel = new();
/// <inheritdoc />
public CancellationToken Cancellation => _cancel.Token;
/// <summary>
/// Manages the pausing.
/// </summary>
private CancellationTokenSource _pause = new();
/// <inheritdoc />
public IScript? CurrentScript => _active;
/// <inheritdoc />
public IScript? MainScript => _active;
/// <summary>
/// Last progress seen.
/// </summary>
private ScriptProgress? _lastProgress;
/// <summary>
/// Script parser to use.
/// </summary>
public IScriptParser Parser { get; } = parser;
private string _codeHash = null!;
/// <summary>
/// Get the current status of the group execution information.
/// </summary>
/// <returns>Group execution status.</returns>
protected ScriptGroupStatus SerializeGroupStatus(bool includeRepeat = false)
=> new()
{
CodeHash = _codeHash,
GroupStatus = _groupManager.Serialize(includeRepeat),
HasBeenPaused = _pause.IsCancellationRequested,
};
/// <inheritdoc/>
public async Task<string> StartAsync(StartScript request, string userToken, StartScriptOptions? options = null)
{
Logger.LogTrace("Script '{Name}' should be started for {Token}.", request.Name, userToken);
try
{
/* Try to create the script instance. */
if (Activator.CreateInstance(request.GetScriptType(), request, this, options) is not Script script)
throw new ArgumentException("bad script for '{Name}' request.", request.Name);
using (Lock.Wait())
{
/* There can be only one active script. */
if (_active != null)
throw new InvalidOperationException("another script is already executing.");
/* Reset the internal state to the new script. */
_inputResponse?.SetException(new OperationCanceledException());
_active = script;
_allProgress.Clear();
_cancel = new();
_codeHash = null!;
_done = false;
_groupManager.Reset(options?.GroupResults?.GroupStatus);
_inputRequest = null;
_inputResponse = null;
_lastProgress = null;
_lastProgressValue = null;
_pause = new();
_activeScope = _rootProvider.CreateScope();
/* If the notion of a user is enabled attach the user to the script execution threads. */
ServiceProvider.GetService<ICurrentUser>()?.FromToken(userToken);
/* Do additional cleanup */
await OnPrepareStartAsync();
Logger.LogTrace("Script '{Name}' started as {JobId}.", request.Name, script.JobId);
/* Process the script on a separate thread. */
Task.Factory.StartNew(RunScriptAsync, CancellationToken.None, TaskCreationOptions.None, TaskScheduler.Current).Touch();
/* Inform all. */
context?
.SendAsync(ScriptEngineNotifyMethods.Started, CreateStartNotification(script))
.ContinueWith(
t => Logger.LogError("Failed to report active script: {Exception}", t.Exception?.Message),
CancellationToken.None,
TaskContinuationOptions.NotOnRanToCompletion,
TaskScheduler.Current)
.Touch();
return script.JobId;
}
}
catch (Exception e)
{
Logger.LogError("Unable to start script '{Name}': {Exception}", request.Name, e.Message);
throw;
}
}
/// <summary>
/// Allow customization to prepare for a script execution.
/// </summary>
protected virtual Task OnPrepareStartAsync() => Task.CompletedTask;
/// <inheritdoc/>
public void Pause(string jobId)
{
using (Lock.Wait())
{
if (_active == null || _active.JobId != jobId)
throw new ArgumentException("not the active script", nameof(jobId));
/* Report the result. */
Logger.LogTrace("User paused script {JobId}", jobId);
_pause.Cancel();
}
}
/// <inheritdoc/>
public void Cancel(string jobId)
{
using (Lock.Wait())
{
if (_active == null || _active.JobId != jobId)
throw new ArgumentException("not the active script", nameof(jobId));
/* Report the result. */
Logger.LogTrace("User cancelled script {JobId}", jobId);
_cancel.Cancel();
/* Abort pending input. */
if (_inputResponse != null && _inputRequest != null)
SetUserInput(new() { JobId = jobId, Key = _inputRequest.Key }, false);
/* Do custom cleanup. */
OnCancel(jobId);
}
}
/// <summary>
/// Cleanup during a cancel operation.
/// </summary>
/// <param name="jobId">The script that has been cancelled.</param>
protected virtual void OnCancel(string jobId) { }
/// <summary>
/// Execute the main script.
/// </summary>
private async Task RunScriptAsync()
{
/* Script to use. */
var script = _active;
if (script == null)
{
Logger.LogError("No active script - internal server error, contact your seller.");
return;
}
/* Potentiall error code. */
Exception? error = null;
try
{
/* Now we can synchronously execute the script. */
await script.ExecuteAsync();
/* Check for cancel. */
_cancel.Token.ThrowIfCancellationRequested();
}
catch (Exception e)
{
/* Something went wrong. */
if (e is AggregateException aggregation && aggregation.InnerExceptions.Count == 1)
error = aggregation.InnerExceptions.Single();
else
error = e;
if (error is TargetInvocationException target)
error = target.InnerException ?? target;
Logger.LogError("Failed to execute script {JobId}: {Exception}", script.JobId, error.Message);
}
try
{
/* Make sure child processes will terminate as soon as possible. */
await _cancel.CancelAsync();
_done = true;
/* Customize. */
await OnScriptDoneAsync(script, null);
/* Forward the information on the now terminated script. */
var task = error == null
? context?.SendAsync(ScriptEngineNotifyMethods.Done, CreateDoneNotification(script))
: context?.SendAsync(ScriptEngineNotifyMethods.Error, CreateErrorNotification(script, error));
/* In case of any error just log - actually this could be quite a problem. */
task?.ContinueWith(
t => Logger.LogError("Failed to finish script: {Exception}", t.Exception?.Message),
CancellationToken.None,
TaskContinuationOptions.NotOnRanToCompletion,
TaskScheduler.Current)
.Touch();
}
catch (Exception e)
{
Logger.LogError("Failed to finish script: {Exception}", e.Message);
}
finally
{
/* In case of execution error forget the running job - elsewhere the script must be ended using GetResult(). */
if (error != null)
FinishScriptAndGetResult(script.JobId);
}
}
/// <summary>
///
/// </summary>
protected virtual Task OnScriptDoneAsync(IScriptInstance script, IScript? parent) => Task.CompletedTask;
/// <inheritdoc/>
public object? FinishScriptAndGetResult(string jobId)
{
using (Lock.Wait())
{
/* Can only get the result for the active script. */
var script = _active;
if (script == null || script.JobId != jobId)
throw new ArgumentException("no the active script", nameof(jobId));
if (!_done)
throw new ArgumentException("script not yet finished", nameof(jobId));
/* Reset active script - result can only be requested once. */
using (_activeScope) _activeScope = null;
_active = null;
/* Report the result. */
Logger.LogTrace("Processing result for script {JobId}", jobId);
/* Inform all. */
context?
.SendAsync(ScriptEngineNotifyMethods.Finished, CreateFinishNotification(script))
.ContinueWith(
t => Logger.LogError("Failed to report active script: {Exception}", t.Exception?.Message),
CancellationToken.None,
TaskContinuationOptions.NotOnRanToCompletion,
TaskScheduler.Current)
.Touch();
return script.Result;
}
}
/// <inheritdoc/>
public Task<object?> EvaluateAsync(string scriptAsXml, Dictionary<string, object?> presets)
{
_codeHash = BitConverter.ToString(SHA256.HashData(Encoding.UTF8.GetBytes(scriptAsXml)));
return Parser.Parse(scriptAsXml).EvaluateAsync(presets, this);
}
/// <inheritdoc/>
public Task<TResult> RunAsync<TResult>(StartScript request, StartScriptOptions? options = null)
=> StartChildAsync<TResult>(request, _active, options, 0);
/// <summary>
/// Finish using this instance.
/// </summary>
public virtual void Dispose()
{
/* Release system resources. */
Lock.Dispose();
}
/// <inheritdoc/>
public void Reconnect(IScriptEngineNotifySink client)
{
using (Lock.Wait())
{
/* Nothing to report. */
if (_active == null) return;
/* Has been started. */
client
.SendAsync(ScriptEngineNotifyMethods.Current, CreateCurrentNotification(_active))
.ContinueWith(
t => Logger.LogError("Failed to report active script: {Exception}", t.Exception?.Message),
CancellationToken.None,
TaskContinuationOptions.NotOnRanToCompletion,
TaskScheduler.Current)
.Touch();
/* Has some last progress. */
if (_lastProgress != null)
client
.SendAsync(ScriptEngineNotifyMethods.Progress, _lastProgress)
.ContinueWith(
t => Logger.LogError("Failed to forward progress: {Exception}", t.Exception?.Message),
CancellationToken.None,
TaskContinuationOptions.NotOnRanToCompletion,
TaskScheduler.Current)
.Touch();
/* Is waiting for input. */
if (_inputRequest != null)
client
.SendAsync(ScriptEngineNotifyMethods.InputRequest, _inputRequest)
.ContinueWith(
t => Logger.LogError("Failed to request user input for script {JobId}: {Exception}", _inputRequest.JobId, t.Exception?.Message),
CancellationToken.None,
TaskContinuationOptions.NotOnRanToCompletion,
TaskScheduler.Current)
.Touch();
/* Script is completed. */
if (_done)
client
.SendAsync(ScriptEngineNotifyMethods.Done, CreateDoneNotification(_active))
.ContinueWith(
t => Logger.LogError("Failed to finish script: {Exception}", t.Exception?.Message),
CancellationToken.None,
TaskContinuationOptions.NotOnRanToCompletion,
TaskScheduler.Current)
.Touch();
}
}
/// <inheritdoc/>
public Task SingleStepAsync(Block block) => Task.CompletedTask;
/// <inheritdoc/>
public bool BeginGroup(string key, string? name) => _groupManager.Start(key, name);
/// <inheritdoc/>
public void EndGroup(GroupResult result)
{
_groupManager.Finish(result);
/* Interrupt right now. */
if (_pause.IsCancellationRequested) throw new ScriptPausedException();
}
/// <inheritdoc/>
public List<object?>? CreateFlatResultFromGroups() => _groupManager.CreateFlatResults();
/// <inheritdoc/>
public Task<List<GroupInfo>> GetGroupsForScriptAsync(string code) => Parser.Parse(code).GetGroupTreeAsync();
}