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/*
* Copyright (c) Peter Bjorklund. All rights reserved. https://github.com/nimble-rust/nimble
* Licensed under the MIT License. See LICENSE in the project root for license information.
*/
use crate::in_logic::Logic;
use crate::prelude::BlobError;
use crate::protocol::TransferId;
use crate::protocol_front::{
AckChunkFrontData, ReceiverToSenderFrontCommands, SenderToReceiverFrontCommands,
};
use crate::ChunkIndex;
use err_rs::{ErrorLevel, ErrorLevelProvider};
use log::{debug, trace};
use std::io;
#[derive(Debug)]
pub enum FrontLogicError {
IoError(io::Error),
BlobError(BlobError),
UnknownTransferId(TransferId),
ChunkSizeCanNotBeZero,
}
impl ErrorLevelProvider for FrontLogicError {
fn error_level(&self) -> ErrorLevel {
match self {
FrontLogicError::IoError(_) => ErrorLevel::Info,
FrontLogicError::BlobError(_) => ErrorLevel::Info,
FrontLogicError::UnknownTransferId(_) => ErrorLevel::Info,
FrontLogicError::ChunkSizeCanNotBeZero => ErrorLevel::Info,
}
}
}
pub struct Info {
pub transfer_id: TransferId,
pub fixed_chunk_size: usize,
pub octet_count: usize,
pub chunk_count_received: usize,
pub waiting_for_chunk_index: ChunkIndex,
}
#[derive(Debug)]
pub struct State {
transfer_id: TransferId,
logic: Logic,
}
/// `Logic` handles the logic for receiving and processing chunks of data
/// in a streaming context. It manages the internal state and interactions
/// between the sender and receiver commands.
#[derive(Debug, Default)]
pub struct FrontLogic {
state: Option<State>,
should_reply_ack: bool,
}
impl FrontLogic {
/// Creates a new `InLogicFront` instance with the specified `octet_count` and `chunk_size`.
///
/// # Arguments
///
/// * `octet_count` - The total number of octets (bytes) expected in the stream.
/// * `chunk_size` - The size of each chunk in the stream.
///
/// # Returns
///
/// A new `InLogicFront` instance.
///
#[must_use]
pub const fn new() -> Self {
Self {
state: None,
should_reply_ack: false,
}
}
/// Updates the internal state based on a `SenderToReceiverFrontCommands` command.
///
/// This method processes either a `StartTransfer` or `SetChunk` command sent by the sender.
/// If a `StartTransfer` command is received, the current state (including `transfer_id` and
/// `logic`) is reinitialized if necessary. If a `SetChunk` command is received, it applies
/// the chunk of data to the current logic.
///
/// # Arguments
///
/// * `command` - A command sent by the sender to either start a new transfer or update
/// an existing one with a chunk of data.
///
/// # Returns
///
/// On success, this method returns a corresponding response:
/// * If a `StartTransfer` command is processed, it returns `AckStart` with the `transfer_id`.
/// * If a `SetChunk` command is processed successfully, it returns `AckChunk` with information
/// on the last chunk received in order as well as a receive-mask for up to 64 chunks
/// after that.
///
/// # Errors
///
/// This function returns an `io::Error` in the following cases:
/// * If a `SetChunk` command is received and the transfer state has not been initialized
/// (i.e., no `StartTransfer` has been processed), it returns an `io::Error` with
/// `ErrorKind::InvalidData` and a message indicating that the `transfer_id` is unknown.
///
/// * Any I/O error encountered during the update of the logic will be propagated.
///
/// # Example
///
/// ```
/// use blob_stream::in_logic_front::FrontLogic;
/// use blob_stream::protocol::StartTransferData;
/// use blob_stream::protocol_front::SenderToReceiverFrontCommands;
///
/// let mut logic_front = FrontLogic::new();
///
/// let start_command = SenderToReceiverFrontCommands::StartTransfer(StartTransferData {
/// transfer_id: 1234,
/// total_octet_size: 1024,
/// chunk_size: 256,
/// });
///
/// let response = logic_front.receive(&start_command);
/// assert!(response.is_ok());
/// ```
pub fn receive(
&mut self,
command: &SenderToReceiverFrontCommands,
) -> Result<(), FrontLogicError> {
match command {
SenderToReceiverFrontCommands::StartTransfer(start_transfer_data) => {
if self
.state
.as_ref()
.map_or(true, |s| s.transfer_id.0 != start_transfer_data.transfer_id)
{
debug!(
"received a start transfer for {}. sending ack.",
start_transfer_data.transfer_id
);
if start_transfer_data.chunk_size == 0 {
Err(FrontLogicError::ChunkSizeCanNotBeZero)?;
}
// Either logic is not set or the transfer_id is different, so we start with a fresh InLogic.
self.state = Some(State {
transfer_id: TransferId(start_transfer_data.transfer_id),
logic: Logic::new(
start_transfer_data.total_octet_size as usize,
start_transfer_data.chunk_size as usize,
),
});
self.should_reply_ack = true;
}
Ok(())
}
SenderToReceiverFrontCommands::SetChunk(chunk_data) => {
if let Some(ref mut state) = self.state {
trace!(
"received chunk {} (transfer:{})",
chunk_data.data.chunk_index,
chunk_data.transfer_id.0
);
state
.logic
.receive(&chunk_data.data)
.map_err(FrontLogicError::BlobError)?;
if state.logic.is_complete() {
trace!("received all chunks!")
}
Ok(())
} else {
Err(FrontLogicError::UnknownTransferId(chunk_data.transfer_id))
}
}
}
}
pub fn send(&mut self) -> Option<ReceiverToSenderFrontCommands> {
if self.should_reply_ack {
self.should_reply_ack = false;
let transfer_id = self.state.as_ref().unwrap().transfer_id.0;
Some(ReceiverToSenderFrontCommands::AckStart(transfer_id))
} else if let Some(state) = self.state.as_mut() {
let ack = &state.logic.send();
Some(ReceiverToSenderFrontCommands::AckChunk(AckChunkFrontData {
transfer_id: state.transfer_id,
data: *ack,
}))
} else {
None
}
}
/// Retrieves the full blob data if all chunks have been received.
///
/// # Returns
///
/// An `Some(&[u8])` containing the full blob data if all chunks have been received,
/// or `None` if the blob is incomplete.
#[must_use]
pub fn blob(&self) -> Option<&[u8]> {
self.state.as_ref().and_then(|state| state.logic.blob())
}
#[must_use]
pub fn info(&self) -> Option<Info> {
self.state.as_ref().map(|s| {
let info = s.logic.info();
Info {
transfer_id: s.transfer_id,
fixed_chunk_size: info.chunk_octet_size,
octet_count: info.total_octet_size,
chunk_count_received: info.chunk_count_received,
waiting_for_chunk_index: info.waiting_for_chunk_index,
}
})
}
}