ln.objects/ng/storage/fs/FSStorageContainer.cs

// /**
//  * File: FSStorage.cs
//  * Author: haraldwolff
//  *
//  * This file and it's content is copyrighted by the Author and / or copyright holder.
//  * Any use wihtout proper permission is illegal and may lead to legal actions.
//  *
//  *
//  **/
using System;
using System.Collections.Generic;
using System.IO;
using System.Diagnostics;
using ln.logging;
using ln.types.odb.ng.storage.cache;

namespace ln.types.odb.ng.storage.fs
{
    public class FSStorageContainer : IStorageContainer,IDisposable
    {
        public string BasePath { get; }
		public int DefaultCacheSize { get; set; }

		FileStream lockFile;
        Dictionary<string, IStorage> storages = new Dictionary<string, IStorage>();

        public FSStorageContainer(string basePath)
        {
            BasePath = basePath;
        }
        public bool IsOpen => lockFile != null;

        private void AssertOpen()
        {
            if (!IsOpen)
                throw new IOException("FSStorage not open");
        }

        public void Close()
        {
            lock (this)
            {
                AssertOpen();

                foreach (IStorage storage in storages.Values)
                {
                    if (storage.IsOpen)
                        storage.Close();
                    storage.Dispose();
                }

                if (lockFile != null)
                {
                    lockFile.Close();
                    lockFile.Dispose();
                    lockFile = null;
                }
            }
        }

        public IStorage GetStorage(string storageName)
        {
            lock (this)
            {
                AssertOpen();

				if (!storages.ContainsKey(storageName))
				{
					IStorage storage = new SegmentedFileStorage(Path.Combine(BasePath, storageName));

					if (DefaultCacheSize > 0)
						storage = new CachingStorage(storage) { MaxCacheSize = DefaultCacheSize, };

					storages.Add(storageName, storage);
				}
                if (!storages[storageName].IsOpen)
                    storages[storageName].Open();

                return storages[storageName];
            }
        }

        public IEnumerable<string> GetStorageNames()
        {
            lock (this)
            {
                AssertOpen();
                return storages.Keys;
            }
        }

        public IStorageContainer Open()
        {
            lock (this)
            {
                if (!IsOpen)
                {
                    if (!Directory.Exists(BasePath))
                        Directory.CreateDirectory(BasePath);

                    try
                    {
                        lockFile = new FileStream(Path.Combine(BasePath, ".lock"), FileMode.CreateNew, FileAccess.ReadWrite, FileShare.Read, 1024, FileOptions.DeleteOnClose);
                        lockFile.WriteInteger(Process.GetCurrentProcess().Id);
                        lockFile.Flush();
                    } catch (IOException)
                    {
                        if (File.Exists(Path.Combine(BasePath, ".lock")))
                        {
                            lockFile = new FileStream(Path.Combine(BasePath, ".lock"), FileMode.Open, FileAccess.Read, FileShare.Read);
                            int lockPID = lockFile.ReadInteger();
                            lockFile.Close();

                            Process lockProcess = null;

                            try
                            {
                                lockProcess = Process.GetProcessById(lockPID);
                            } catch (Exception)
                            {
                            }

                            if ((lockProcess != null) && !lockProcess.HasExited)
                                    throw;

                            Logging.Log(LogLevel.DEBUG, "FSStorageContainer: Ignoring stale lock file: PID:{0}@{1}", lockPID,Path.Combine(BasePath, ".lock"));

                            lockFile = new FileStream(Path.Combine(BasePath, ".lock"), FileMode.Truncate, FileAccess.ReadWrite, FileShare.Read, 1024, FileOptions.DeleteOnClose);
                            lockFile.WriteInteger(Process.GetCurrentProcess().Id);
                            lockFile.Flush();
                        }
                    }
                }
            }
            return this;
        }

        public void Dispose()
        {
            if (IsOpen)
                Close();
            storages.Clear();
        }
    }
}