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GeezerVison is showing github.com — Npgsql/src/Npgsql/NpgsqlLargeObjectManager.cs at main · roji/Npgsql Expand file tree/ Copy pathNpgsqlLargeObjectManager.csMore file actions 265 lines (233 loc) · 12.6 KB / Copy pathNpgsqlLargeObjectManager.csFile metadata and controls265 lines (233 loc) · 12.6 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 using System; using System.Data; using System.Threading; using System.Threading.Tasks; namespace Npgsql { /// <summary> /// Large object manager. This class can be used to store very large files in a PostgreSQL database. /// </summary> public class NpgsqlLargeObjectManager { const int InvWrite = 0x00020000; const int InvRead = 0x00040000; internal NpgsqlConnection Connection { get; } /// <summary> /// The largest chunk size (in bytes) read and write operations will read/write each roundtrip to the network. Default 4 MB. /// </summary> public int MaxTransferBlockSize { get; set; } /// <summary> /// Creates an NpgsqlLargeObjectManager for this connection. The connection must be opened to perform remote operations. /// </summary> /// <param name="connection"></param> public NpgsqlLargeObjectManager(NpgsqlConnection connection) { Connection = connection; MaxTransferBlockSize = 4 * 1024 * 1024; // 4MB } /// <summary> /// Execute a function /// </summary> internal async Task<T> ExecuteFunction<T>(string function, bool async, CancellationToken cancellationToken, params object[] arguments) { using var command = new NpgsqlCommand(function, Connection) { CommandType = CommandType.StoredProcedure, CommandText = function }; foreach (var argument in arguments) command.Parameters.Add(new NpgsqlParameter { Value = argument }); return (T)(async ? await command.ExecuteScalarAsync(cancellationToken) : command.ExecuteScalar())!; } /// <summary> /// Execute a function that returns a byte array /// </summary> /// <returns></returns> internal async Task<int> ExecuteFunctionGetBytes( string function, byte[] buffer, int offset, int len, bool async, CancellationToken cancellationToken, params object[] arguments) { using var command = new NpgsqlCommand(function, Connection) { CommandType = CommandType.StoredProcedure }; foreach (var argument in arguments) command.Parameters.Add(new NpgsqlParameter { Value = argument }); using var reader = async ? await command.ExecuteReaderAsync(CommandBehavior.SequentialAccess, cancellationToken) : command.ExecuteReader(CommandBehavior.SequentialAccess); if (async) await reader.ReadAsync(cancellationToken); else reader.Read(); return (int)reader.GetBytes(0, 0, buffer, offset, len); } /// <summary> /// Create an empty large object in the database. If an oid is specified but is already in use, an PostgresException will be thrown. /// </summary> /// <param name="preferredOid">A preferred oid, or specify 0 if one should be automatically assigned</param> /// <returns>The oid for the large object created</returns> /// <exception cref="PostgresException">If an oid is already in use</exception> public uint Create(uint preferredOid = 0) => Create(preferredOid, false).GetAwaiter().GetResult(); // Review unused parameters /// <summary> /// Create an empty large object in the database. If an oid is specified but is already in use, an PostgresException will be thrown. /// </summary> /// <param name="preferredOid">A preferred oid, or specify 0 if one should be automatically assigned</param> /// <param name="cancellationToken"> /// An optional token to cancel the asynchronous operation. The default value is <see cref="CancellationToken.None"/>. /// </param> /// <returns>The oid for the large object created</returns> /// <exception cref="PostgresException">If an oid is already in use</exception> public Task<uint> CreateAsync(uint preferredOid, CancellationToken cancellationToken = default) => Create(preferredOid, true, cancellationToken); Task<uint> Create(uint preferredOid, bool async, CancellationToken cancellationToken = default) => ExecuteFunction<uint>("lo_create", async, cancellationToken, (int)preferredOid); /// <summary> /// Opens a large object on the backend, returning a stream controlling this remote object. /// A transaction snapshot is taken by the backend when the object is opened with only read permissions. /// When reading from this object, the contents reflects the time when the snapshot was taken. /// Note that this method, as well as operations on the stream must be wrapped inside a transaction. /// </summary> /// <param name="oid">Oid of the object</param> /// <returns>An NpgsqlLargeObjectStream</returns> public NpgsqlLargeObjectStream OpenRead(uint oid) => OpenRead(oid, false).GetAwaiter().GetResult(); /// <summary> /// Opens a large object on the backend, returning a stream controlling this remote object. /// A transaction snapshot is taken by the backend when the object is opened with only read permissions. /// When reading from this object, the contents reflects the time when the snapshot was taken. /// Note that this method, as well as operations on the stream must be wrapped inside a transaction. /// </summary> /// <param name="oid">Oid of the object</param> /// <param name="cancellationToken"> /// An optional token to cancel the asynchronous operation. The default value is <see cref="CancellationToken.None"/>. /// </param> /// <returns>An NpgsqlLargeObjectStream</returns> public Task<NpgsqlLargeObjectStream> OpenReadAsync(uint oid, CancellationToken cancellationToken = default) { using (NoSynchronizationContextScope.Enter()) return OpenRead(oid, true, cancellationToken); } async Task<NpgsqlLargeObjectStream> OpenRead(uint oid, bool async, CancellationToken cancellationToken = default) { var fd = await ExecuteFunction<int>("lo_open", async, cancellationToken, (int)oid, InvRead); return new NpgsqlLargeObjectStream(this, fd, false); } /// <summary> /// Opens a large object on the backend, returning a stream controlling this remote object. /// Note that this method, as well as operations on the stream must be wrapped inside a transaction. /// </summary> /// <param name="oid">Oid of the object</param> /// <returns>An NpgsqlLargeObjectStream</returns> public NpgsqlLargeObjectStream OpenReadWrite(uint oid) => OpenReadWrite(oid, false).GetAwaiter().GetResult(); /// <summary> /// Opens a large object on the backend, returning a stream controlling this remote object. /// Note that this method, as well as operations on the stream must be wrapped inside a transaction. /// </summary> /// <param name="oid">Oid of the object</param> /// <param name="cancellationToken"> /// An optional token to cancel the asynchronous operation. The default value is <see cref="CancellationToken.None"/>. /// </param> /// <returns>An NpgsqlLargeObjectStream</returns> public Task<NpgsqlLargeObjectStream> OpenReadWriteAsync(uint oid, CancellationToken cancellationToken = default) { using (NoSynchronizationContextScope.Enter()) return OpenReadWrite(oid, true, cancellationToken); } async Task<NpgsqlLargeObjectStream> OpenReadWrite(uint oid, bool async, CancellationToken cancellationToken = default) { var fd = await ExecuteFunction<int>("lo_open", async, cancellationToken, (int)oid, InvRead | InvWrite); return new NpgsqlLargeObjectStream(this, fd, true); } /// <summary> /// Deletes a large object on the backend. /// </summary> /// <param name="oid">Oid of the object to delete</param> public void Unlink(uint oid) => ExecuteFunction<object>("lo_unlink", false, CancellationToken.None, (int)oid).GetAwaiter().GetResult(); /// <summary> /// Deletes a large object on the backend. /// </summary> /// <param name="oid">Oid of the object to delete</param> /// <param name="cancellationToken"> /// An optional token to cancel the asynchronous operation. The default value is <see cref="CancellationToken.None"/>. /// </param> public Task UnlinkAsync(uint oid, CancellationToken cancellationToken = default) { using (NoSynchronizationContextScope.Enter()) return ExecuteFunction<object>("lo_unlink", true, cancellationToken, (int)oid); } /// <summary> /// Exports a large object stored in the database to a file on the backend. This requires superuser permissions. /// </summary> /// <param name="oid">Oid of the object to export</param> /// <param name="path">Path to write the file on the backend</param> public void ExportRemote(uint oid, string path) => ExecuteFunction<object>("lo_export", false, CancellationToken.None, (int)oid, path).GetAwaiter().GetResult(); /// <summary> /// Exports a large object stored in the database to a file on the backend. This requires superuser permissions. /// </summary> /// <param name="oid">Oid of the object to export</param> /// <param name="path">Path to write the file on the backend</param> /// <param name="cancellationToken"> /// An optional token to cancel the asynchronous operation. The default value is <see cref="CancellationToken.None"/>. /// </param> public Task ExportRemoteAsync(uint oid, string path, CancellationToken cancellationToken = default) { using (NoSynchronizationContextScope.Enter()) return ExecuteFunction<object>("lo_export", true, cancellationToken, (int)oid, path); } /// <summary> /// Imports a large object to be stored as a large object in the database from a file stored on the backend. This requires superuser permissions. /// </summary> /// <param name="path">Path to read the file on the backend</param> /// <param name="oid">A preferred oid, or specify 0 if one should be automatically assigned</param> public void ImportRemote(string path, uint oid = 0) => ExecuteFunction<object>("lo_import", false, CancellationToken.None, path, (int)oid).GetAwaiter().GetResult(); /// <summary> /// Imports a large object to be stored as a large object in the database from a file stored on the backend. This requires superuser permissions. /// </summary> /// <param name="path">Path to read the file on the backend</param> /// <param name="oid">A preferred oid, or specify 0 if one should be automatically assigned</param> /// <param name="cancellationToken"> /// An optional token to cancel the asynchronous operation. The default value is <see cref="CancellationToken.None"/>. /// </param> public Task ImportRemoteAsync(string path, uint oid, CancellationToken cancellationToken = default) { using (NoSynchronizationContextScope.Enter()) return ExecuteFunction<object>("lo_import", true, cancellationToken, path, (int)oid); } /// <summary> /// Since PostgreSQL 9.3, large objects larger than 2GB can be handled, up to 4TB. /// This property returns true whether the PostgreSQL version is >= 9.3. /// </summary> public bool Has64BitSupport => Connection.PostgreSqlVersion >= new Version(9, 3); /* internal enum Function : uint { lo_open = 952, lo_close = 953, loread = 954, lowrite = 955, lo_lseek = 956, lo_lseek64 = 3170, // Since PostgreSQL 9.3 lo_creat = 957, lo_create = 715, lo_tell = 958, lo_tell64 = 3171, // Since PostgreSQL 9.3 lo_truncate = 1004, lo_truncate64 = 3172, // Since PostgreSQL 9.3 // These four are available since PostgreSQL 9.4 lo_from_bytea = 3457, lo_get = 3458, lo_get_fragment = 3459, lo_put = 3460, lo_unlink = 964, lo_import = 764, lo_import_with_oid = 767, lo_export = 765, } */ } } |
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