FilesModule.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Waher.Events;
using Waher.Runtime.Inventory;
using Waher.Things.Metering;
using Waher.Things.Metering.NodeTypes;
using Waher.Things.Virtual;
 
namespace Waher.Things.Files
{
    [Singleton]
    public class FilesModule : IModule
    {
        private static readonly Dictionary<string, KeyValuePair<FolderNode, FileSystemWatcher>> watchers = new Dictionary<string, KeyValuePair<FolderNode, FileSystemWatcher>>();
        private static readonly SemaphoreSlim synchObj = new SemaphoreSlim(1);
 
        public async Task Start()
        {
            try
            {
                await this.CheckNode(MeteringTopology.Root);
            }
            catch (Exception ex)
            {
                Log.Exception(ex);
            }
        }
 
        private async Task CheckNode(INode Node)
        {
            foreach (INode Child in await Node.ChildNodes)
            {
                if (Child is FolderNode FolderNode)
                {
                    try
                    {
                        await FolderNode.Synchronize();
                    }
                    catch (Exception ex)
                    {
                        Log.Exception(ex);
                    }
                }
                else if (Child is VirtualNode || Child is NodeCollection)
                    await this.CheckNode(Child);
            }
        }
 
        public async Task Stop()
        {
            await synchObj.WaitAsync();
            try
            {
                foreach (KeyValuePair<FolderNode, FileSystemWatcher> P in watchers.Values)
                    P.Value.Dispose();
 
                watchers.Clear();
            }
            finally
            {
                synchObj.Release();
            }
        }
 
        internal static async Task StopSynchronization(string FolderPath)
        {
            await synchObj.WaitAsync();
            try
            {
                if (watchers.TryGetValue(FolderPath, out KeyValuePair<FolderNode, FileSystemWatcher> P))
                {
                    watchers.Remove(FolderPath);
                    P.Value.Dispose();
                }
            }
            finally
            {
                synchObj.Release();
            }
        }
 
        internal static async Task CheckSynchronization(FolderNode Node)
        {
            try
            {
                FileSystemWatcher Watcher;
 
                await synchObj.WaitAsync();
                try
                {
                    if (watchers.TryGetValue(Node.FolderPath, out KeyValuePair<FolderNode, FileSystemWatcher> P))
                    {
                        P.Value.Changed -= Node.Watcher_Changed;
                        P.Value.Created -= Node.Watcher_Created;
                        P.Value.Deleted -= Node.Watcher_Deleted;
                        P.Value.Renamed -= Node.Watcher_Renamed;
                        P.Value.Error -= Node.Watcher_Error;
                        
                        P.Value.EnableRaisingEvents = false;
 
                        watchers.Remove(Node.FolderPath);
                        P.Value.Dispose();
                    }
 
                    if (!Directory.Exists(Node.FolderPath))
                        Directory.CreateDirectory(Node.FolderPath);
 
                    if (Node.SynchronizationOptions != SynchronizationOptions.NoSynchronization)
                    {
                        if (string.IsNullOrEmpty(Node.FileFilter))
                            Watcher = new FileSystemWatcher(Node.FolderPath);
                        else
                            Watcher = new FileSystemWatcher(Node.FolderPath, Node.FileFilter);
 
                        watchers[Node.FolderPath] = new KeyValuePair<FolderNode, FileSystemWatcher>(Node, Watcher);
 
                        Watcher.InternalBufferSize = 65536;
                        Watcher.NotifyFilter =
                            NotifyFilters.Attributes |
                            NotifyFilters.CreationTime |
                            NotifyFilters.DirectoryName |
                            NotifyFilters.FileName |
                            NotifyFilters.LastAccess |
                            NotifyFilters.LastWrite |
                            NotifyFilters.Security |
                            NotifyFilters.Size;
 
                        Watcher.Changed += Node.Watcher_Changed;
                        Watcher.Created += Node.Watcher_Created;
                        Watcher.Deleted += Node.Watcher_Deleted;
                        Watcher.Renamed += Node.Watcher_Renamed;
                        Watcher.Error += Node.Watcher_Error;
 
                        Watcher.IncludeSubdirectories = Node.SynchronizationOptions == SynchronizationOptions.IncludeSubfolders;
                        Watcher.EnableRaisingEvents = true;
                    }
                }
                finally
                {
                    synchObj.Release();
                }
 
                await Node.SynchFolder();
                await Node.RemoveErrorAsync("SynchError");
            }
            catch (Exception ex)
            {
                await Node.LogErrorAsync("SynchError", ex.Message);
            }
        }
    }
}