/// <summary>
/// Reads <i>count</i> bytes from the large object. The only case when fewer bytes are read is when end of stream is reached.
/// </summary>
/// <param name="buffer">The buffer where read data should be stored.</param>
/// <param name="offset">The offset in the buffer where the first byte should be read.</param>
/// <param name="count">The maximum number of bytes that should be read.</param>
/// <param name="cancellationToken">Cancellation token</param>
/// <returns>How many bytes actually read, or 0 if end of file was already reached.</returns>
public override Task <int> ReadAsync(byte[] buffer, int offset, int count,
CancellationToken cancellationToken)
=> SynchronizationContextSwitcher.NoContext(async() =>
{
cancellationToken.ThrowIfCancellationRequested();
return(await Read(buffer, offset, count, true));
});
/// <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">Cancellation token.</param>
public Task ImportRemoteAsync(string path, uint oid, CancellationToken cancellationToken)
=> SynchronizationContextSwitcher.NoContext(async() =>
{
cancellationToken.ThrowIfCancellationRequested();
await ExecuteFunction <object>("lo_import", true, path, (int)oid);
});
/// <summary>
/// Deletes a large object on the backend.
/// </summary>
/// <param name="oid">Oid of the object to delete</param>
/// <param name="cancellationToken">Cancellation token.</param>
public Task UnlinkAsync(uint oid, CancellationToken cancellationToken)
=> SynchronizationContextSwitcher.NoContext(async() =>
{
cancellationToken.ThrowIfCancellationRequested();
await ExecuteFunction <object>("lo_unlink", true, (int)oid);
});
/// <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">Cancellation token.</param>
/// <returns>An NpgsqlLargeObjectStream</returns>
public Task <NpgsqlLargeObjectStream> OpenReadWriteAsync(uint oid, CancellationToken cancellationToken)
=> SynchronizationContextSwitcher.NoContext(async() =>
{
cancellationToken.ThrowIfCancellationRequested();
return(await OpenReadWrite(oid, true));
});
public Task RollbackAsync(CancellationToken cancellationToken)
=> SynchronizationContextSwitcher.NoContext(async() =>
{
cancellationToken.ThrowIfCancellationRequested();
await Rollback(true, cancellationToken);
});
/// <summary>
/// Writes <i>count</i> bytes to the large object.
/// </summary>
/// <param name="buffer">The buffer to write data from.</param>
/// <param name="offset">The offset in the buffer at which to begin copying bytes.</param>
/// <param name="count">The number of bytes to write.</param>
/// <param name="cancellationToken">Cancellation token.</param>
public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
=> SynchronizationContextSwitcher.NoContext(async() =>
{
cancellationToken.ThrowIfCancellationRequested();
await Write(buffer, offset, count, true);
});
