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using System;
using System.Diagnostics;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;
using Npgsql.BackendMessages;
using Npgsql.Internal;
using static Npgsql.Util.Statics;
#pragma warning disable 1591
namespace Npgsql;
/// <summary>
/// Provides an API for a raw binary COPY operation, a high-performance data import/export mechanism to
/// a PostgreSQL table. Initiated by <see cref="NpgsqlConnection.BeginRawBinaryCopy(string)"/>
/// </summary>
/// <remarks>
/// See https://www.postgresql.org/docs/current/static/sql-copy.html.
/// </remarks>
public sealed class NpgsqlRawCopyStream : Stream, ICancelable
{
#region Fields and Properties
NpgsqlConnector _connector;
NpgsqlReadBuffer _readBuf;
NpgsqlWriteBuffer _writeBuf;
int _leftToReadInDataMsg;
bool _isDisposed, _isConsumed;
bool _canRead;
bool _canWrite;
internal bool IsBinary { get; private set; }
public override bool CanWrite => _canWrite;
public override bool CanRead => _canRead;
public override bool CanTimeout => true;
public override int WriteTimeout
{
get => (int) _writeBuf.Timeout.TotalMilliseconds;
set => _writeBuf.Timeout = TimeSpan.FromMilliseconds(value);
}
public override int ReadTimeout
{
get => (int) _readBuf.Timeout.TotalMilliseconds;
set
{
_readBuf.Timeout = TimeSpan.FromMilliseconds(value);
// While calling the connector it will overwrite our read buffer timeout
_connector.UserTimeout = value;
}
}
/// <summary>
/// The copy binary format header signature
/// </summary>
internal static readonly byte[] BinarySignature =
{
(byte)'P',(byte)'G',(byte)'C',(byte)'O',(byte)'P',(byte)'Y',
(byte)'\n', 255, (byte)'\r', (byte)'\n', 0
};
static readonly ILogger Logger = NpgsqlLoggingConfiguration.CopyLogger;
#endregion
#region Constructor / Initializer
internal NpgsqlRawCopyStream(NpgsqlConnector connector)
{
_connector = connector;
_readBuf = connector.ReadBuffer;
_writeBuf = connector.WriteBuffer;
}
internal async Task Init(string copyCommand, bool async, CancellationToken cancellationToken = default)
{
await _connector.WriteQuery(copyCommand, async, cancellationToken);
await _connector.Flush(async, cancellationToken);
using var registration = _connector.StartNestedCancellableOperation(cancellationToken, attemptPgCancellation: false);
var msg = await _connector.ReadMessage(async);
switch (msg.Code)
{
case BackendMessageCode.CopyInResponse:
var copyInResponse = (CopyInResponseMessage) msg;
IsBinary = copyInResponse.IsBinary;
_canWrite = true;
_writeBuf.StartCopyMode();
break;
case BackendMessageCode.CopyOutResponse:
var copyOutResponse = (CopyOutResponseMessage) msg;
IsBinary = copyOutResponse.IsBinary;
_canRead = true;
break;
case BackendMessageCode.CommandComplete:
throw new InvalidOperationException(
"This API only supports import/export from the client, i.e. COPY commands containing TO/FROM STDIN. " +
"To import/export with files on your PostgreSQL machine, simply execute the command with ExecuteNonQuery. " +
"Note that your data has been successfully imported/exported.");
default:
throw _connector.UnexpectedMessageReceived(msg.Code);
}
}
#endregion
#region Write
public override void Write(byte[] buffer, int offset, int count)
{
ValidateArguments(buffer, offset, count);
Write(new ReadOnlySpan<byte>(buffer, offset, count));
}
public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
{
ValidateArguments(buffer, offset, count);
return WriteAsync(new Memory<byte>(buffer, offset, count), cancellationToken).AsTask();
}
#if NETSTANDARD2_0
public void Write(ReadOnlySpan<byte> buffer)
#else
public override void Write(ReadOnlySpan<byte> buffer)
#endif
{
CheckDisposed();
if (!CanWrite)
throw new InvalidOperationException("Stream not open for writing");
if (buffer.Length == 0) { return; }
if (buffer.Length <= _writeBuf.WriteSpaceLeft)
{
_writeBuf.WriteBytes(buffer);
return;
}
try
{
// Value is too big, flush.
Flush();
if (buffer.Length <= _writeBuf.WriteSpaceLeft)
{
_writeBuf.WriteBytes(buffer);
return;
}
// Value is too big even after a flush - bypass the buffer and write directly.
_writeBuf.DirectWrite(buffer);
}
catch (Exception e)
{
_connector.Break(e);
throw;
}
}
#if NETSTANDARD2_0
public ValueTask WriteAsync(ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken = default)
#else
public override ValueTask WriteAsync(ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken = default)
#endif
{
CheckDisposed();
if (!CanWrite)
throw new InvalidOperationException("Stream not open for writing");
cancellationToken.ThrowIfCancellationRequested();
using (NoSynchronizationContextScope.Enter())
return WriteAsyncInternal(buffer, cancellationToken);
async ValueTask WriteAsyncInternal(ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken)
{
if (buffer.Length == 0)
return;
if (buffer.Length <= _writeBuf.WriteSpaceLeft)
{
_writeBuf.WriteBytes(buffer.Span);
return;
}
try
{
// Value is too big, flush.
await FlushAsync(true, cancellationToken);
if (buffer.Length <= _writeBuf.WriteSpaceLeft)
{
_writeBuf.WriteBytes(buffer.Span);
return;
}
// Value is too big even after a flush - bypass the buffer and write directly.
await _writeBuf.DirectWrite(buffer, true, cancellationToken);
}
catch (Exception e)
{
_connector.Break(e);
throw;
}
}
}
public override void Flush() => FlushAsync(false).GetAwaiter().GetResult();
public override Task FlushAsync(CancellationToken cancellationToken)
{
if (cancellationToken.IsCancellationRequested)
return Task.FromCanceled(cancellationToken);
using (NoSynchronizationContextScope.Enter())
return FlushAsync(true, cancellationToken);
}
Task FlushAsync(bool async, CancellationToken cancellationToken = default)
{
CheckDisposed();
return _writeBuf.Flush(async, cancellationToken);
}
#endregion
#region Read
public override int Read(byte[] buffer, int offset, int count)
{
ValidateArguments(buffer, offset, count);
return Read(new Span<byte>(buffer, offset, count));
}
public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
{
ValidateArguments(buffer, offset, count);
return ReadAsync(new Memory<byte>(buffer, offset, count), cancellationToken).AsTask();
}
#if NETSTANDARD2_0
public int Read(Span<byte> span)
#else
public override int Read(Span<byte> span)
#endif
{
CheckDisposed();
if (!CanRead)
throw new InvalidOperationException("Stream not open for reading");
var count = ReadCore(span.Length, false).GetAwaiter().GetResult();
if (count > 0)
_readBuf.ReadBytes(span.Slice(0, count));
return count;
}
#if NETSTANDARD2_0
public ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken)
#else
public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken)
#endif
{
CheckDisposed();
if (!CanRead)
throw new InvalidOperationException("Stream not open for reading");
cancellationToken.ThrowIfCancellationRequested();
using (NoSynchronizationContextScope.Enter())
return ReadAsyncInternal();
async ValueTask<int> ReadAsyncInternal()
{
var count = await ReadCore(buffer.Length, true, cancellationToken);
if (count > 0)
_readBuf.ReadBytes(buffer.Slice(0, count).Span);
return count;
}
}
async ValueTask<int> ReadCore(int count, bool async, CancellationToken cancellationToken = default)
{
if (_isConsumed)
return 0;
using var registration = _connector.StartNestedCancellableOperation(cancellationToken, attemptPgCancellation: false);
if (_leftToReadInDataMsg == 0)
{
IBackendMessage msg;
try
{
// We've consumed the current DataMessage (or haven't yet received the first),
// read the next message
msg = await _connector.ReadMessage(async);
}
catch
{
if (!_isDisposed)
Cleanup();
throw;
}
switch (msg.Code)
{
case BackendMessageCode.CopyData:
_leftToReadInDataMsg = ((CopyDataMessage)msg).Length;
break;
case BackendMessageCode.CopyDone:
Expect<CommandCompleteMessage>(await _connector.ReadMessage(async), _connector);
Expect<ReadyForQueryMessage>(await _connector.ReadMessage(async), _connector);
_isConsumed = true;
return 0;
default:
throw _connector.UnexpectedMessageReceived(msg.Code);
}
}
Debug.Assert(_leftToReadInDataMsg > 0);
// If our buffer is empty, read in more. Otherwise return whatever is there, even if the
// user asked for more (normal socket behavior)
if (_readBuf.ReadBytesLeft == 0)
await _readBuf.ReadMore(async);
Debug.Assert(_readBuf.ReadBytesLeft > 0);
var maxCount = Math.Min(_readBuf.ReadBytesLeft, _leftToReadInDataMsg);
if (count > maxCount)
count = maxCount;
_leftToReadInDataMsg -= count;
return count;
}
#endregion
#region Cancel
/// <summary>
/// Cancels and terminates an ongoing operation. Any data already written will be discarded.
/// </summary>
public void Cancel() => Cancel(false).GetAwaiter().GetResult();
/// <summary>
/// Cancels and terminates an ongoing operation. Any data already written will be discarded.
/// </summary>
public Task CancelAsync()
{
using (NoSynchronizationContextScope.Enter())
return Cancel(true);
}
async Task Cancel(bool async)
{
CheckDisposed();
if (CanWrite)
{
_writeBuf.EndCopyMode();
_writeBuf.Clear();
await _connector.WriteCopyFail(async);
await _connector.Flush(async);
try
{
var msg = await _connector.ReadMessage(async);
// The CopyFail should immediately trigger an exception from the read above.
throw _connector.Break(
new NpgsqlException("Expected ErrorResponse when cancelling COPY but got: " + msg.Code));
}
catch (PostgresException e)
{
_connector.EndUserAction();
Cleanup();
if (e.SqlState != PostgresErrorCodes.QueryCanceled)
throw;
}
}
else
{
_connector.PerformPostgresCancellation();
}
}
#endregion
#region Dispose
protected override void Dispose(bool disposing) => DisposeAsync(disposing, false).GetAwaiter().GetResult();
#if NETSTANDARD2_0
public ValueTask DisposeAsync()
#else
public override ValueTask DisposeAsync()
#endif
=> DisposeAsync(disposing: true, async: true);
async ValueTask DisposeAsync(bool disposing, bool async)
{
if (_isDisposed || !disposing)
return;
try
{
_connector.CurrentCopyOperation = null;
if (CanWrite)
{
await FlushAsync(async);
_writeBuf.EndCopyMode();
await _connector.WriteCopyDone(async);
await _connector.Flush(async);
Expect<CommandCompleteMessage>(await _connector.ReadMessage(async), _connector);
Expect<ReadyForQueryMessage>(await _connector.ReadMessage(async), _connector);
}
else
{
if (!_isConsumed)
{
try
{
if (_leftToReadInDataMsg > 0)
{
await _readBuf.Skip(_leftToReadInDataMsg, async);
}
_connector.SkipUntil(BackendMessageCode.ReadyForQuery);
}
catch (OperationCanceledException e) when (e.InnerException is PostgresException pg && pg.SqlState == PostgresErrorCodes.QueryCanceled)
{
LogMessages.CopyOperationCancelled(Logger, _connector.Id);
}
catch (Exception e)
{
LogMessages.ExceptionWhenDisposingCopyOperation(Logger, _connector.Id, e);
}
}
}
}
finally
{
_connector.EndUserAction();
Cleanup();
}
}
#pragma warning disable CS8625
void Cleanup()
{
Debug.Assert(!_isDisposed);
LogMessages.CopyOperationCompleted(Logger, _connector.Id);
_connector.CurrentCopyOperation = null;
_connector.Connection?.EndBindingScope(ConnectorBindingScope.Copy);
_connector = null;
_readBuf = null;
_writeBuf = null;
_isDisposed = true;
}
#pragma warning restore CS8625
void CheckDisposed()
{
if (_isDisposed) {
throw new ObjectDisposedException(nameof(NpgsqlRawCopyStream), "The COPY operation has already ended.");
}
}
#endregion
#region Unsupported
public override bool CanSeek => false;
public override long Seek(long offset, SeekOrigin origin)
{
throw new NotSupportedException();
}
public override void SetLength(long value)
{
throw new NotSupportedException();
}
public override long Length => throw new NotSupportedException();
public override long Position
{
get => throw new NotSupportedException();
set => throw new NotSupportedException();
}
#endregion
#region Input validation
static void ValidateArguments(byte[] buffer, int offset, int count)
{
if (buffer == null)
throw new ArgumentNullException(nameof(buffer));
if (offset < 0)
throw new ArgumentNullException(nameof(offset));
if (count < 0)
throw new ArgumentNullException(nameof(count));
if (buffer.Length - offset < count)
throw new ArgumentException("Offset and length were out of bounds for the array or count is greater than the number of elements from index to the end of the source collection.");
}
#endregion
}
/// <summary>
/// Writer for a text import, initiated by <see cref="NpgsqlConnection.BeginTextImport(string)"/>.
/// </summary>
/// <remarks>
/// See https://www.postgresql.org/docs/current/static/sql-copy.html.
/// </remarks>
public sealed class NpgsqlCopyTextWriter : StreamWriter, ICancelable
{
internal NpgsqlCopyTextWriter(NpgsqlConnector connector, NpgsqlRawCopyStream underlying) : base(underlying)
{
if (underlying.IsBinary)
throw connector.Break(new Exception("Can't use a binary copy stream for text writing"));
}
/// <summary>
/// Cancels and terminates an ongoing import. Any data already written will be discarded.
/// </summary>
public void Cancel()
=> ((NpgsqlRawCopyStream)BaseStream).Cancel();
/// <summary>
/// Cancels and terminates an ongoing import. Any data already written will be discarded.
/// </summary>
public Task CancelAsync()
{
using (NoSynchronizationContextScope.Enter())
return ((NpgsqlRawCopyStream)BaseStream).CancelAsync();
}
#if NETSTANDARD2_0
public ValueTask DisposeAsync()
{
Dispose();
return default;
}
#endif
}
/// <summary>
/// Reader for a text export, initiated by <see cref="NpgsqlConnection.BeginTextExport(string)"/>.
/// </summary>
/// <remarks>
/// See https://www.postgresql.org/docs/current/static/sql-copy.html.
/// </remarks>
public sealed class NpgsqlCopyTextReader : StreamReader, ICancelable
{
internal NpgsqlCopyTextReader(NpgsqlConnector connector, NpgsqlRawCopyStream underlying) : base(underlying)
{
if (underlying.IsBinary)
throw connector.Break(new Exception("Can't use a binary copy stream for text reading"));
}
/// <summary>
/// Cancels and terminates an ongoing export.
/// </summary>
public void Cancel()
=> ((NpgsqlRawCopyStream)BaseStream).Cancel();
/// <summary>
/// Asynchronously cancels and terminates an ongoing export.
/// </summary>
public Task CancelAsync()
{
using (NoSynchronizationContextScope.Enter())
return ((NpgsqlRawCopyStream)BaseStream).CancelAsync();
}
public ValueTask DisposeAsync()
{
Dispose();
return default;
}
}