forked from npgsql/npgsql
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathNpgsqlLargeObjectManager.cs
More file actions
258 lines (232 loc) · 12.8 KB
/
NpgsqlLargeObjectManager.cs
File metadata and controls
258 lines (232 loc) · 12.8 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
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 INV_WRITE = 0x00020000;
const int INV_READ = 0x00040000;
internal readonly NpgsqlConnection _connection;
/// <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, params object[] arguments)
{
using (var command = new NpgsqlCommand(function, _connection))
{
command.CommandType = CommandType.StoredProcedure;
command.CommandText = function;
foreach (var argument in arguments)
command.Parameters.Add(new NpgsqlParameter { Value = argument });
return (T)(async ? await command.ExecuteScalarAsync() : 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, params object[] arguments)
{
using (var command = new NpgsqlCommand(function, _connection))
{
command.CommandType = CommandType.StoredProcedure;
foreach (var argument in arguments)
command.Parameters.Add(new NpgsqlParameter { Value = argument });
using (var reader = async ? await command.ExecuteReaderAsync(CommandBehavior.SequentialAccess) : command.ExecuteReader(CommandBehavior.SequentialAccess))
{
if (async)
await reader.ReadAsync();
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">The token to monitor for cancellation requests. 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)
=> cancellationToken.IsCancellationRequested
? Task.FromCanceled<uint>(cancellationToken)
: Create(preferredOid, true);
Task<uint> Create(uint preferredOid, bool async)
=> ExecuteFunction<uint>("lo_create", async, (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">The token to monitor for cancellation requests. The default value is <see cref="CancellationToken.None"/>.</param>
/// <returns>An NpgsqlLargeObjectStream</returns>
public Task<NpgsqlLargeObjectStream> OpenReadAsync(uint oid, CancellationToken cancellationToken = default)
{
if (cancellationToken.IsCancellationRequested)
return Task.FromCanceled<NpgsqlLargeObjectStream>(cancellationToken);
using (NoSynchronizationContextScope.Enter())
return OpenRead(oid, true);
}
async Task<NpgsqlLargeObjectStream> OpenRead(uint oid, bool async)
{
var fd = await ExecuteFunction<int>("lo_open", async, (int)oid, INV_READ);
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">The token to monitor for cancellation requests. The default value is <see cref="CancellationToken.None"/>.</param>
/// <returns>An NpgsqlLargeObjectStream</returns>
public Task<NpgsqlLargeObjectStream> OpenReadWriteAsync(uint oid, CancellationToken cancellationToken = default)
{
if (cancellationToken.IsCancellationRequested)
return Task.FromCanceled<NpgsqlLargeObjectStream>(cancellationToken);
using (NoSynchronizationContextScope.Enter())
return OpenReadWrite(oid, true);
}
async Task<NpgsqlLargeObjectStream> OpenReadWrite(uint oid, bool async)
{
var fd = await ExecuteFunction<int>("lo_open", async, (int)oid, INV_READ | INV_WRITE);
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, (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">The token to monitor for cancellation requests. The default value is <see cref="CancellationToken.None"/>.</param>
public Task UnlinkAsync(uint oid, CancellationToken cancellationToken = default)
{
if (cancellationToken.IsCancellationRequested)
return Task.FromCanceled(cancellationToken);
using (NoSynchronizationContextScope.Enter())
return ExecuteFunction<object>("lo_unlink", true, (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, (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">The token to monitor for cancellation requests. The default value is <see cref="CancellationToken.None"/>.</param>
public Task ExportRemoteAsync(uint oid, string path, CancellationToken cancellationToken = default)
{
if (cancellationToken.IsCancellationRequested)
return Task.FromCanceled(cancellationToken);
using (NoSynchronizationContextScope.Enter())
return ExecuteFunction<object>("lo_export", true, (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, 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">The token to monitor for cancellation requests. The default value is <see cref="CancellationToken.None"/>.</param>
public Task ImportRemoteAsync(string path, uint oid, CancellationToken cancellationToken = default)
{
if (cancellationToken.IsCancellationRequested)
return Task.FromCanceled(cancellationToken);
using (NoSynchronizationContextScope.Enter())
return ExecuteFunction<object>("lo_import", true, 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,
}
*/
}
}