Initial commit

srcs/RobotNet10/RobotApp/Communication/CartographerSharp/IO/ProtoStreamWriter.cs

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+/*
+ * Copyright 2016 The Cartographer Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System.IO.Compression;
+using System.Text;
+using System.Text.Json;
+
+namespace CartographerSharp.IO;
+
+/// <summary>
+/// A simple writer of a compressed sequence of protocol buffer messages to a file.
+/// The format is not intended to be compatible with any other format used outside of Cartographer.
+/// </summary>
+public class ProtoStreamWriter : IProtoStreamWriter, IDisposable
+{
+    // First eight bytes to identify our proto stream format.
+    private const ulong Magic = 0x7b1d1f7b5bf501db;
+
+    private static readonly JsonSerializerOptions JsonOptions = new()
+    {
+        WriteIndented = false,
+        DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.Never
+    };
+
+    private readonly FileStream _fileStream;
+    private bool _disposed;
+    private bool _magicWritten;
+
+    public ProtoStreamWriter(string filename)
+    {
+        if (string.IsNullOrEmpty(filename))
+            throw new ArgumentException("Filename cannot be null or empty", nameof(filename));
+
+        _fileStream = new FileStream(filename, FileMode.Create, FileAccess.Write, FileShare.Read);
+        WriteMagic();
+    }
+
+    private void WriteMagic()
+    {
+        WriteSizeAsLittleEndian(Magic);
+        _magicWritten = true;
+    }
+
+    private void WriteSizeAsLittleEndian(ulong size)
+    {
+        for (int i = 0; i < 8; i++)
+        {
+            _fileStream.WriteByte((byte)(size & 0xff));
+            size >>= 8;
+        }
+    }
+
+    private void Write(string uncompressedData)
+    {
+        if (!_magicWritten)
+        {
+            WriteMagic();
+        }
+
+        // Compress using GZip
+        byte[] uncompressedBytes = Encoding.UTF8.GetBytes(uncompressedData);
+        byte[] compressedBytes;
+        
+        using (var memoryStream = new MemoryStream())
+        {
+            using (var gzipStream = new GZipStream(memoryStream, CompressionMode.Compress, leaveOpen: true))
+            {
+                gzipStream.Write(uncompressedBytes, 0, uncompressedBytes.Length);
+            }
+            compressedBytes = memoryStream.ToArray();
+        }
+
+        // Write compressed size
+        WriteSizeAsLittleEndian((ulong)compressedBytes.Length);
+        
+        // Write compressed data
+        _fileStream.Write(compressedBytes, 0, compressedBytes.Length);
+    }
+
+    /// <summary>
+    /// Serializes, compresses and writes the proto to the file.
+    /// </summary>
+    public void WriteProto<T>(T proto)
+    {
+        ArgumentNullException.ThrowIfNull(proto, nameof(proto));
+
+        // Serialize to JSON (we use System.Text.Json instead of Google.Protobuf)
+        string json = JsonSerializer.Serialize(proto, JsonOptions);
+
+        Write(json);
+    }
+
+    /// <summary>
+    /// This should be called to check whether writing was successful.
+    /// </summary>
+    public bool Close()
+    {
+        if (_disposed)
+            return false;
+
+        _fileStream.Flush();
+        _fileStream.Close();
+        _disposed = true; // Prevent Dispose() from calling Close() again (double-close would throw on Flush)
+        return true;
+    }
+
+    public void Dispose()
+    {
+        if (!_disposed)
+        {
+            Close();
+            _fileStream?.Dispose();
+            _disposed = true;
+        }
+
+        GC.SuppressFinalize(this);
+    }
+}