public override TEnum Read(NpgsqlReadBuffer buf, int len, FieldDescription?fieldDescription = null)
{
var str = buf.ReadString(len);
var success = _labelToEnum.TryGetValue(str, out var value);
if (!success)
{
throw new InvalidCastException($"Received enum value '{str}' from database which wasn't found on enum {typeof(TEnum)}");
}
return(value);
}
static async ValueTask <string> ReadLong(NpgsqlReadBuffer buf, int byteLen, bool async)
{
if (byteLen <= buf.Size)
{
// The string's byte representation can fit in our read buffer, read it.
while (buf.ReadBytesLeft < byteLen)
{
await buf.ReadMore(async);
}
return(buf.ReadString(byteLen));
}
// Bad case: the string's byte representation doesn't fit in our buffer.
// This is rare - will only happen in CommandBehavior.Sequential mode (otherwise the
// entire row is in memory). Tweaking the buffer length via the connection string can
// help avoid this.
// Allocate a temporary byte buffer to hold the entire string and read it in chunks.
var tempBuf = new byte[byteLen];
var pos = 0;
while (true)
{
var len = Math.Min(buf.ReadBytesLeft, byteLen - pos);
buf.ReadBytes(tempBuf, pos, len);
pos += len;
if (pos < byteLen)
{
await buf.ReadMore(async);
continue;
}
break;
}
return(buf.TextEncoding.GetString(tempBuf));
}
/// <inheritdoc />
public override ValueTask <string> Read(NpgsqlReadBuffer buf, int byteLen, bool async, FieldDescription?fieldDescription = null)
{
return(buf.ReadBytesLeft >= byteLen
? new ValueTask <string>(buf.ReadString(byteLen))
: ReadLong(buf, byteLen, async));
