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Diffstat (limited to 'lib/VNLib.Plugins.Extensions.Data/src/Storage/BlobStore.cs')
| -rw-r--r-- | lib/VNLib.Plugins.Extensions.Data/src/Storage/BlobStore.cs | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/lib/VNLib.Plugins.Extensions.Data/src/Storage/BlobStore.cs b/lib/VNLib.Plugins.Extensions.Data/src/Storage/BlobStore.cs new file mode 100644 index 0000000..6897516 --- /dev/null +++ b/lib/VNLib.Plugins.Extensions.Data/src/Storage/BlobStore.cs @@ -0,0 +1,162 @@ +/* +* Copyright (c) 2022 Vaughn Nugent +* +* Library: VNLib +* Package: VNLib.Plugins.Extensions.Data +* File: BlobStore.cs +* +* BlobStore.cs is part of VNLib.Plugins.Extensions.Data which is part of the larger +* VNLib collection of libraries and utilities. +* +* VNLib.Plugins.Extensions.Data is free software: you can redistribute it and/or modify +* it under the terms of the GNU General Public License as published +* by the Free Software Foundation, either version 2 of the License, +* or (at your option) any later version. +* +* VNLib.Plugins.Extensions.Data is distributed in the hope that it will be useful, +* but WITHOUT ANY WARRANTY; without even the implied warranty of +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +* General Public License for more details. +* +* You should have received a copy of the GNU General Public License +* along with VNLib.Plugins.Extensions.Data. If not, see http://www.gnu.org/licenses/. +*/ + +using System; +using System.IO; +using System.Security.Cryptography; +using System.Threading.Tasks; + +using VNLib.Utils.Extensions; + +namespace VNLib.Plugins.Extensions.Data.Storage +{ + + /// <summary> + /// Stores <see cref="Blob"/>s to the local file system backed with a single table <see cref="LWStorageManager"/> + /// that tracks changes + /// </summary> + public class BlobStore + { + /// <summary> + /// The root directory all blob files are stored + /// </summary> + public DirectoryInfo RootDir { get; } + /// <summary> + /// The backing store for blob meta-data + /// </summary> + protected LWStorageManager BlobTable { get; } + /// <summary> + /// Creates a new <see cref="BlobStore"/> that accesses files + /// within the specified root directory. + /// </summary> + /// <param name="rootDir">The root directory containing the blob file contents</param> + /// <param name="blobStoreMan">The db backing store</param> + public BlobStore(DirectoryInfo rootDir, LWStorageManager blobStoreMan) + { + RootDir = rootDir; + BlobTable = blobStoreMan; + } + + private string GetPath(string fileId) => Path.Combine(RootDir.FullName, fileId); + + /* + * Creates a repeatable unique identifier for the file + * name and allows for lookups + */ + internal static string CreateFileHash(string fileName) + { + throw new NotImplementedException(); + //return ManagedHash.ComputeBase64Hash(fileName, HashAlg.SHA1); + } + + /// <summary> + /// Opens an existing <see cref="Blob"/> from the current store + /// </summary> + /// <param name="fileId">The id of the file being requested</param> + /// <param name="access">Access level of the file</param> + /// <param name="share">The sharing option of the underlying file</param> + /// <param name="bufferSize">The size of the file buffer</param> + /// <returns>If found, the requested <see cref="Blob"/>, null otherwise. Throws exceptions if the file is opened in a non-sharable state</returns> + /// <exception cref="IOException"></exception> + /// <exception cref="NotSupportedException"></exception> + /// <exception cref="ArgumentNullException"></exception> + /// <exception cref="UnauthorizedAccessException"></exception> + /// <exception cref="UndefinedBlobStateException"></exception> + public virtual async Task<Blob> OpenBlobAsync(string fileId, FileAccess access, FileShare share, int bufferSize = 4096) + { + //Get the file's data descriptor + LWStorageDescriptor fileDescriptor = await BlobTable.GetDescriptorFromIDAsync(fileId); + //return null if not found + if (fileDescriptor == null) + { + return null; + } + try + { + string fsSafeName = GetPath(fileDescriptor.DescriptorID); + //try to open the file + FileStream file = new(fsSafeName, FileMode.Open, access, share, bufferSize, FileOptions.Asynchronous); + //Create the new blob + return new Blob(fileDescriptor, file); + } + catch (FileNotFoundException) + { + //If the file was not found but the descriptor was, delete the descriptor from the db + fileDescriptor.Delete(); + //Flush changes + await fileDescriptor.ReleaseAsync(); + //return null since this is a desync issue and the file technically does not exist + return null; + } + catch + { + //Release the descriptor and pass the exception + await fileDescriptor.ReleaseAsync(); + throw; + } + } + + /// <summary> + /// Creates a new <see cref="Blob"/> for the specified file sharing permissions + /// </summary> + /// <param name="name">The name of the original file</param> + /// <param name="share">The blob sharing permissions</param> + /// <param name="bufferSize"></param> + /// <returns>The newly created <see cref="Blob"/></returns> + /// <exception cref="IoExtensions"></exception> + /// <exception cref="NotSupportedException"></exception> + /// <exception cref="ArgumentNullException"></exception> + /// <exception cref="UnauthorizedAccessException"></exception> + public virtual async Task<Blob> CreateBlobAsync(string name, FileShare share = FileShare.None, int bufferSize = 4096) + { + //hash the file name to create a unique id for the file name + LWStorageDescriptor newFile = await BlobTable.CreateDescriptorAsync(CreateFileHash(name)); + //if the descriptor was not created, return null + if (newFile == null) + { + return null; + } + try + { + string fsSafeName = GetPath(newFile.DescriptorID); + //Open/create the new file + FileStream file = new(fsSafeName, FileMode.OpenOrCreate, FileAccess.ReadWrite, share, bufferSize, FileOptions.Asynchronous); + //If the file already exists, make sure its zero'd + file.SetLength(0); + //Save the original name of the file + newFile.SetName(name); + //Create and return the new blob + return new Blob(newFile, file); + } + catch + { + //If an exception occurs, remove the descritor from the db + newFile.Delete(); + await newFile.ReleaseAsync(); + //Pass exception + throw; + } + } + } +}
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