public Event[] GetAndClearPendingEvents(MemoryPool <byte> pool)
{
FFIOperationWithVariableLengthReturnBuffer func =
(bufOut, bufLength) =>
{
var ffiResult = Interop.test_event_serialization(bufOut, bufLength, out var actualLength);
return(ffiResult, actualLength);
};
var arr = WithVariableLengthReturnBuffer(pool, func);
return(Event.ParseManyUnsafe(arr));
}
private ChannelDetails[] ChannelDetailsInterop()
{
FFIOperationWithVariableLengthReturnBuffer func =
(bufOut, bufLength) =>
{
var ffiResult = Interop.test_channel_details_serialization(bufOut, bufLength, out var actualLen);
return(ffiResult, actualLen);
};
var arr = WithVariableLengthReturnBuffer(_pool, func);
return(ChannelDetails.ParseManyUnsafe(arr));
}
/// <summary>
/// Use this function when ffi function returns variable length return value
/// It will rent `BUFFER_SIZE_UNIT` bytes from MemoryPool and tries to write a return value
/// in to it. If the length was not enough, then it will try again with longer buffer.
/// This process continues until the buffer reaches MAX_BUFFER_SIZE, and it will throws FFIException
/// When that is even not enough.
/// </summary>
/// <param name="pool"></param>
/// <param name="func"> actual ffi function, first argument is a pointer to a allocated buffer, second is the length of it, and third is a parent SafeHandle class</param>
/// <returns></returns>
/// <exception cref="FFIException"></exception>
internal static byte[] WithVariableLengthReturnBuffer(
MemoryPool <byte> pool, FFIOperationWithVariableLengthReturnBuffer func)
{
var initialBufLength = BUFFER_SIZE_UNIT;
var(resultBuf, result, actualBufferLength) = InvokeWithLength(pool, initialBufLength, func);
if (actualBufferLength > MAX_BUFFER_SIZE)
{
throw new FFIException(
$"Tried to return too long buffer form rust ({actualBufferLength}). This should never happen.",
result);
}
if (result.IsSuccess)
{
return(resultBuf[..actualBufferLength]);