1 // Npgsql.NpgsqlCopyOutStream.cs
4 // Kalle Hallivuori <kato@iki.fi>
6 // Copyright (C) 2007 The Npgsql Development Team
7 // npgsql-general@gborg.postgresql.org
8 // http://gborg.postgresql.org/project/npgsql/projdisplay.php
10 // Permission to use, copy, modify, and distribute this software and its
11 // documentation for any purpose, without fee, and without a written
12 // agreement is hereby granted, provided that the above copyright notice
13 // and this paragraph and the following two paragraphs appear in all copies.
15 // IN NO EVENT SHALL THE NPGSQL DEVELOPMENT TEAM BE LIABLE TO ANY PARTY
16 // FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
17 // INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
18 // DOCUMENTATION, EVEN IF THE NPGSQL DEVELOPMENT TEAM HAS BEEN ADVISED OF
19 // THE POSSIBILITY OF SUCH DAMAGE.
21 // THE NPGSQL DEVELOPMENT TEAM SPECIFICALLY DISCLAIMS ANY WARRANTIES,
22 // INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
23 // AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
24 // ON AN "AS IS" BASIS, AND THE NPGSQL DEVELOPMENT TEAM HAS NO OBLIGATIONS
25 // TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
34 /// Stream for reading data from a table or select on a PostgreSQL version 7.4 or newer database during an active COPY TO STDOUT operation.
35 /// <b>Passes data exactly as provided by the server.</b>
37 internal class NpgsqlCopyOutStream
: Stream
39 private NpgsqlConnector _context
;
40 private long _bytesPassed
= 0;
41 private byte[] _buf
= null;
42 private int _bufOffset
= 0;
45 /// True while this stream can be used to read copy data from server
49 get { return _context != null && _context.CurrentState is NpgsqlCopyOutState && _context.Mediator.CopyStream == this; }
53 /// Created only by NpgsqlCopyOutState.StartCopy()
55 internal NpgsqlCopyOutStream(NpgsqlConnector context
)
63 public override bool CanRead
71 public override bool CanWrite
79 public override bool CanSeek
85 /// Number of bytes read so far
87 public override long Length
89 get { return _bytesPassed; }
93 /// Number of bytes read so far; can not be set.
95 public override long Position
97 get { return _bytesPassed; }
98 set { throw new NotSupportedException("Tried to set Position of network stream " + this); }
102 /// Discards copy data as long as server pushes it. Returns after operation is finished.
103 /// Does nothing if this stream is not the active copy operation reader.
105 public override void Close()
107 if (_context
!= null)
111 while (_context
.CurrentState
.GetCopyData(_context
) != null)
116 if (_context
.Mediator
.CopyStream
== this)
118 _context
.Mediator
.CopyStream
= null;
127 public override void Write(byte[] buf
, int off
, int len
)
129 throw new NotSupportedException("Tried to write non-writable " + this);
135 public override void Flush()
137 throw new NotSupportedException("Tried to flush read-only " + this);
141 /// Copies data read from server to given byte buffer.
142 /// Since server returns data row by row, length will differ each time, but it is only zero once the operation ends.
143 /// Can be mixed with calls to the more efficient NpgsqlCopyOutStream.Read() : byte[] though that would not make much sense.
145 public override int Read(byte[] buf
, int off
, int len
)
149 throw new ObjectDisposedException("Reading from closed " + this);
152 if (_buf
== null) // otherwise _buf still contains data that did not fit into request buffer in an earlier call
157 if (off
+ len
> buf
.Length
)
159 len
= buf
.Length
- off
;
165 for (; _bufOffset
< _buf
.Length
&& i
< len
; i
++)
167 buf
[off
+ i
] = _buf
[_bufOffset
++];
169 if (_bufOffset
>= _buf
.Length
)
171 _buf
= null; // whole of our contents fit into request buffer
181 public override long Seek(long pos
, SeekOrigin so
)
183 throw new NotSupportedException("Tried to seek non-seekable " + this);
189 public override void SetLength(long len
)
191 throw new NotSupportedException("Tried to set length of network stream " + this);
195 /// Returns a whole row of data from server without extra work.
196 /// If standard Stream.Read(...) has been called before, it's internal buffers remains are returned.
203 result
= _context
.CurrentState
.GetCopyData(_context
);
205 else if (_bufOffset
< 1)
211 result
= new byte[_buf
.Length
- _bufOffset
];
212 for (int i
= 0; i
< result
.Length
; i
++)
214 result
[i
] = _buf
[_bufOffset
+ i
];