RepositoryManager.cs

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using LibGit2Sharp;
using Microsoft.Extensions.Logging;
using System;
using System.Threading;
using System.Threading.Tasks;
using Tgstation.Server.Api.Models;
using Tgstation.Server.Host.Components.Events;
using Tgstation.Server.Host.Core;
using Tgstation.Server.Host.IO;
using Tgstation.Server.Host.Jobs;

namespace Tgstation.Server.Host.Components.Repository
{
    sealed class RepositoryManager : IRepositoryManager
    {
        public bool InUse => semaphore.CurrentCount == 0;

        public bool CloneInProgress { get; private set; }

        readonly ILibGit2RepositoryFactory repositoryFactory;

        readonly ILibGit2Commands commands;

        readonly IIOManager ioManager;

        readonly IEventConsumer eventConsumer;

        readonly ILogger<Repository> repositoryLogger;

        readonly ILogger<RepositoryManager> logger;

        readonly SemaphoreSlim semaphore;

        public RepositoryManager(
            ILibGit2RepositoryFactory repositoryFactory,
            ILibGit2Commands commands,
            IIOManager ioManager,
            IEventConsumer eventConsumer,
            ILogger<Repository> repositoryLogger,
            ILogger<RepositoryManager> logger)
        {
            this.repositoryFactory = repositoryFactory ?? throw new ArgumentNullException(nameof(repositoryFactory));
            this.commands = commands ?? throw new ArgumentNullException(nameof(commands));
            this.ioManager = ioManager ?? throw new ArgumentNullException(nameof(ioManager));
            this.eventConsumer = eventConsumer ?? throw new ArgumentNullException(nameof(eventConsumer));
            this.repositoryLogger = repositoryLogger ?? throw new ArgumentNullException(nameof(repositoryLogger));
            this.logger = logger ?? throw new ArgumentNullException(nameof(logger));
            semaphore = new SemaphoreSlim(1);
        }

        public void Dispose()
        {
            logger.LogTrace("Disposing...");
            semaphore.Dispose();
        }

        public async Task<IRepository> CloneRepository(Uri url, string initialBranch, string username, string password, Action<int> progressReporter, CancellationToken cancellationToken)
        {
            if (url == null)
                throw new ArgumentNullException(nameof(url));
            if (progressReporter == null)
                throw new ArgumentNullException(nameof(progressReporter));

            logger.LogInformation("Begin clone {0} (Branch: {1})", url, initialBranch);
            lock (semaphore)
            {
                if (CloneInProgress)
                    throw new JobException(ErrorCode.RepoCloning);
                CloneInProgress = true;
            }

            try
            {
                using (await SemaphoreSlimContext.Lock(semaphore, cancellationToken).ConfigureAwait(false))
                {
                    logger.LogTrace("Semaphore acquired");
                    var repositoryPath = ioManager.ResolvePath();
                    if (!await ioManager.DirectoryExists(repositoryPath, cancellationToken).ConfigureAwait(false))
                        try
                        {
                            var cloneOptions = new CloneOptions
                            {
                                OnProgress = (a) => !cancellationToken.IsCancellationRequested,
                                OnTransferProgress = (a) =>
                                {
                                    var percentage = 100 * (((float)a.IndexedObjects + a.ReceivedObjects) / (a.TotalObjects * 2));
                                    progressReporter((int)percentage);
                                    return !cancellationToken.IsCancellationRequested;
                                },
                                RecurseSubmodules = true,
                                OnUpdateTips = (a, b, c) => !cancellationToken.IsCancellationRequested,
                                RepositoryOperationStarting = (a) => !cancellationToken.IsCancellationRequested,
                                BranchName = initialBranch,
                                CredentialsProvider = repositoryFactory.GenerateCredentialsHandler(username, password)
                            };

                            await repositoryFactory.Clone(
                                url,
                                cloneOptions,
                                repositoryPath,
                                cancellationToken)
                                .ConfigureAwait(false);
                        }
                        catch
                        {
                            try
                            {
                                logger.LogTrace("Deleting partially cloned repository...");
                                await ioManager.DeleteDirectory(repositoryPath, default).ConfigureAwait(false);
                            }
                            catch (Exception e)
                            {
                                logger.LogDebug("Error deleting partially cloned repository! Exception: {0}", e);
                            }

                            throw;
                        }
                    else
                    {
                        logger.LogDebug("Repository exists, clone aborted!");
                        return null;
                    }
                }

                logger.LogInformation("Clone complete!");
            }
            finally
            {
                CloneInProgress = false;
            }

            return await LoadRepository(cancellationToken).ConfigureAwait(false);
        }

        public async Task<IRepository> LoadRepository(CancellationToken cancellationToken)
        {
            logger.LogTrace("Begin LoadRepository...");
            lock (semaphore)
                if (CloneInProgress)
                    throw new JobException(ErrorCode.RepoCloning);
            await semaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
            try
            {
                try
                {
                    var libGitRepo = await repositoryFactory.CreateFromPath(ioManager.ResolvePath(), cancellationToken).ConfigureAwait(false);
                    return new Repository(
                        libGitRepo,
                        commands,
                        ioManager,
                        eventConsumer,
                        repositoryFactory,
                        repositoryLogger, () =>
                    {
                        logger.LogTrace("Releasing semaphore due to Repository disposal...");
                        semaphore.Release();
                    });
                }
                catch
                {
                    semaphore.Release();
                    throw;
                }
            }
            catch (RepositoryNotFoundException e)
            {
                logger.LogDebug("Repository not found!");
                logger.LogTrace("Exception: {0}", e);
                return null;
            }
        }

        public async Task DeleteRepository(CancellationToken cancellationToken)
        {
            logger.LogInformation("Deleting repository...");
            using (await SemaphoreSlimContext.Lock(semaphore, cancellationToken).ConfigureAwait(false))
            {
                logger.LogTrace("Semaphore acquired, deleting Repository directory...");
                await ioManager.DeleteDirectory(ioManager.ResolvePath(), cancellationToken).ConfigureAwait(false);
            }
        }
    }
}