Updating docs

This commit is contained in:
Ryan Summers 2021-06-15 13:18:16 +02:00
parent a54d855cbe
commit 2815d6d9e9
5 changed files with 309 additions and 44 deletions

2
Cargo.lock generated
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@ -811,7 +811,7 @@ dependencies = [
[[package]]
name = "stm32h7xx-hal"
version = "0.9.0"
source = "git+https://github.com/quartiq/stm32h7xx-hal.git?branch=feature/smoltcp-update#191b1d50a8a4d956492649630efaf563f59e35bf"
source = "git+https://github.com/quartiq/stm32h7xx-hal.git?rev=33aa67d#33aa67d74790cb9f680a4f281b72df0664bcf03c"
dependencies = [
"bare-metal 1.0.0",
"cast",

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@ -0,0 +1,189 @@
#!/usr/bin/python3
"""
Author: Ryan Summers
Description: Provides a mechanism for measuring Stabilizer stream data throughput.
"""
import socket
import collections
import struct
import time
import logging
# Representation of a single UDP packet transmitted by Stabilizer.
Packet = collections.namedtuple('Packet', ['index', 'adc', 'dac'])
class Timer:
""" A basic timer for measuring elapsed time periods. """
def __init__(self, period=1.0):
""" Create the timer with the provided period. """
self.start_time = time.time()
self.trigger_time = self.start_time + period
self.period = period
self.started = False
def is_triggered(self):
""" Check if the timer period has elapsed. """
now = time.time()
return now >= self.trigger_time
def start(self):
""" Start the timer. """
self.start_time = time.time()
self.started = True
def is_started(self):
""" Check if the timer has started. """
return self.started
def arm(self):
""" Arm the timer trigger. """
self.trigger_time = time.time() + self.period
def elapsed(self):
""" Get the elapsed time since the timer was started. """
now = time.time()
return now - self.start_time
class PacketParser:
""" Utilize class used for parsing received UDP data. """
def __init__(self):
""" Initialize the parser. """
self.buf = b''
self.total_bytes = 0
def ingress(self, data):
""" Ingress received UDP data. """
self.total_bytes += len(data)
self.buf += data
def parse_all_packets(self):
""" Parse all received packets from the receive buffer.
Returns:
A list of received Packets.
"""
packets = []
while True:
new_packets = self._parse()
if new_packets:
packets += new_packets
else:
return packets
def _parse(self):
""" Attempt to parse packets from the received buffer. """
# Attempt to parse a block from the buffer.
if len(self.buf) < 4:
return None
start_id, num_blocks, data_size = struct.unpack_from('!HBB', self.buf)
packet_size = 4 + data_size * num_blocks * 8
if len(self.buf) < packet_size:
return None
self.buf = self.buf[4:]
packets = []
for offset in range(num_blocks):
adcs_dacs = struct.unpack_from(f'!{4 * data_size}H', self.buf)
adc = [
adcs_dacs[0:data_size],
adcs_dacs[data_size:2*data_size],
]
dac = [
adcs_dacs[2*data_size: 3*data_size],
adcs_dacs[3*data_size:],
]
self.buf = self.buf[8*data_size:]
packets.append(Packet(start_id + offset, adc, dac))
return packets
def check_index(previous_index, next_index):
""" Check if two indices are sequential. """
if previous_index == -1:
return True
# Handle index roll-over. Indices are only stored in 16-bit numbers.
if next_index < previous_index:
next_index += 65536
expected_index = previous_index + 1
return next_index == expected_index
def main():
""" Main program. """
connection = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
connection.bind(("", 1111))
logging.basicConfig(level=logging.INFO,
format='%(asctime)s.%(msecs)03d %(levelname)-8s %(message)s')
last_index = -1
drop_count = 0
good_blocks = 0
timer = Timer()
parser = PacketParser()
while True:
# Receive any data over UDP and parse it.
data = connection.recv(4096)
if data and not timer.is_started():
timer.start()
parser.ingress(data)
# Handle any received packets.
for packet in parser.parse_all_packets():
# Handle any dropped packets.
if not check_index(last_index, packet.index):
print(hex(last_index), hex(packet.index))
if packet.index < (last_index + 1):
dropped = packet.index + 65536 - (last_index + 1)
else:
dropped = packet.index - (last_index + 1)
drop_count += dropped
last_index = packet.index
good_blocks += 1
# Report the throughput periodically.
if timer.is_triggered():
drate = parser.total_bytes * 8 / 1e6 / timer.elapsed()
print(f'''
Data Rate: {drate:.3f} Mbps
Received Blocks: {good_blocks}
Dropped blocks: {drop_count}
Metadata: {parser.total_bytes / 1e6:.3f} MB in {timer.elapsed():.2f} s
----
''')
timer.arm()
if __name__ == '__main__':
main()

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@ -95,8 +95,7 @@ const APP: () = {
stabilizer.net.mac_address,
);
let generator =
network.enable_streaming(StreamTarget::default().into());
let generator = network.enable_streaming();
// Spawn a settings update for default settings.
c.spawn.settings_update().unwrap();

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@ -1,3 +1,20 @@
///! Stabilizer data stream capabilities
///!
///! # Design
///! Stabilizer data streamining utilizes UDP packets to send live data streams at high throughput.
///! Packets are always sent in a best-effort fashion, and data may be dropped. Each packet contains
///! an identifier that can be used to detect any dropped data.
///!
///! The current implementation utilizes an single-producer, single-consumer queue to send data
///! between a high priority task and the UDP transmitter.
///!
///! A "batch" of data is defined to be a single item in the SPSC queue sent to the UDP transmitter
///! thread. The transmitter thread then serializes as many sequential "batches" into a single UDP
///! packet as possible. The UDP packet is also given a header indicating the starting batch
///! sequence number and the number of batches present. If the UDP transmitter encounters a
///! non-sequential batch, it does not enqueue it into the packet and instead transmits any staged
///! data. The non-sequential batch is then transmitted in a new UDP packet. This method allows a
///! receiver to detect dropped batches (e.g. due to processing overhead).
use core::borrow::BorrowMut;
use heapless::spsc::{Consumer, Producer, Queue};
use miniconf::MiniconfAtomic;
@ -10,8 +27,10 @@ use crate::hardware::design_parameters::SAMPLE_BUFFER_SIZE;
// The number of data blocks that we will buffer in the queue.
const BLOCK_BUFFER_SIZE: usize = 30;
// A factor that data may be subsampled at.
const SUBSAMPLE_RATE: usize = 1;
/// Represents the destination for the UDP stream to send data to.
#[derive(Copy, Clone, Debug, MiniconfAtomic, Deserialize)]
pub struct StreamTarget {
pub ip: [u8; 4],
@ -38,6 +57,23 @@ impl Into<SocketAddr> for StreamTarget {
}
}
/// A basic "batch" of data.
// Note: In the future, the stream may be generic over this type.
#[derive(Debug, Copy, Clone)]
pub struct AdcDacData {
block_id: u16,
adcs: [[u16; SAMPLE_BUFFER_SIZE]; 2],
dacs: [[u16; SAMPLE_BUFFER_SIZE]; 2],
}
/// Configure streaming on a device.
///
/// # Args
/// * `stack` - A reference to the shared network stack.
///
/// # Returns
/// (generator, stream) where `generator` can be used to enqueue "batches" for transmission. The
/// `stream` is the logically consumer (UDP transmitter) of the enqueued data.
pub fn setup_streaming(
stack: NetworkReference,
) -> (BlockGenerator, DataStream) {
@ -52,28 +88,34 @@ pub fn setup_streaming(
(generator, stream)
}
#[derive(Debug, Copy, Clone)]
pub struct AdcDacData {
block_id: u16,
adcs: [[u16; SAMPLE_BUFFER_SIZE]; 2],
dacs: [[u16; SAMPLE_BUFFER_SIZE]; 2],
}
/// The data generator for a stream.
pub struct BlockGenerator {
queue: Producer<'static, AdcDacData, BLOCK_BUFFER_SIZE>,
current_id: u16,
}
impl BlockGenerator {
pub fn new(
queue: Producer<'static, AdcDacData, BLOCK_BUFFER_SIZE>,
) -> Self {
/// Construct a new generator.
/// # Args
/// * `queue` - The producer portion of the SPSC queue to enqueue data into.
///
/// # Returns
/// The generator to use.
fn new(queue: Producer<'static, AdcDacData, BLOCK_BUFFER_SIZE>) -> Self {
Self {
queue,
current_id: 0,
}
}
/// Schedule data to be sent by the generator.
///
/// # Note
/// If no space is available, the data batch may be silently dropped.
///
/// # Args
/// * `adcs` - The ADC data to transmit.
/// * `dacs` - The DAC data to transmit.
pub fn send(
&mut self,
adcs: &[&mut [u16; SAMPLE_BUFFER_SIZE]; 2],
@ -90,26 +132,21 @@ impl BlockGenerator {
}
}
pub struct DataStream {
stack: NetworkReference,
socket: Option<<NetworkReference as UdpClientStack>::UdpSocket>,
queue: Consumer<'static, AdcDacData, BLOCK_BUFFER_SIZE>,
remote: Option<SocketAddr>,
buffer: [u8; 1024],
}
// Datapacket format:
//
// Header:
// [0..2]: Start block ID (u16)
// [2..3]: Num Blocks present (u8) <N>
// [3..4]: Batch Size (u8) <BS>
//
// Following the header, batches are added sequentially. Each batch takes the form of:
// [<BS>*0..<BS>*2]: ADC0
// [<BS>*2..<BS>*4]: ADC1
// [<BS>*4..<BS>*6]: DAC0
// [<BS>*6..<BS>*8]: DAC1
/// Represents a single UDP packet sent by the stream.
///
/// # Packet Format
/// All data is sent in network-endian format. The format is as follows
///
/// Header:
/// [0..2]: Start block ID (u16)
/// [2..3]: Num Blocks present (u8) <N>
/// [3..4]: Batch Size (u8) <BS>
///
/// Following the header, batches are added sequentially. Each batch takes the form of:
/// [<BS>*0..<BS>*2]: ADC0
/// [<BS>*2..<BS>*4]: ADC1
/// [<BS>*4..<BS>*6]: DAC0
/// [<BS>*6..<BS>*8]: DAC1
struct DataPacket<'a> {
buf: &'a mut [u8],
subsample_rate: usize,
@ -119,6 +156,11 @@ struct DataPacket<'a> {
}
impl<'a> DataPacket<'a> {
/// Construct a new packet.
///
/// # Args
/// * `buf` - The location to serialize the data packet into.
/// * `subsample_rate` - The factor at which to subsample data from batches.
pub fn new(buf: &'a mut [u8], subsample_rate: usize) -> Self {
Self {
buf,
@ -129,6 +171,13 @@ impl<'a> DataPacket<'a> {
}
}
/// Add a batch of data to the packet.
///
/// # Note
/// Serialization occurs as the packet is added.
///
/// # Args
/// * `batch` - The batch to add to the packet.
pub fn add_batch(&mut self, batch: &AdcDacData) -> Result<(), ()> {
// Check that the block is sequential.
if let Some(id) = &self.start_id {
@ -170,6 +219,11 @@ impl<'a> DataPacket<'a> {
block_size_bytes * self.num_blocks as usize + header_length
}
/// Complete the packet and prepare it for transmission.
///
/// # Returns
/// The size of the packet. The user should utilize the original buffer provided for packet
/// construction to access the packet.
pub fn finish(self) -> usize {
let block_sample_size = SAMPLE_BUFFER_SIZE / self.subsample_rate;
@ -183,15 +237,32 @@ impl<'a> DataPacket<'a> {
}
}
/// The "consumer" portion of the data stream.
///
/// # Note
/// This is responsible for consuming data and sending it over UDP.
pub struct DataStream {
stack: NetworkReference,
socket: Option<<NetworkReference as UdpClientStack>::UdpSocket>,
queue: Consumer<'static, AdcDacData, BLOCK_BUFFER_SIZE>,
remote: SocketAddr,
buffer: [u8; 1024],
}
impl DataStream {
pub fn new(
/// Construct a new data streamer.
///
/// # Args
/// * `stack` - A reference to the shared network stack.
/// * `consumer` - The read side of the queue containing data to transmit.
fn new(
stack: NetworkReference,
consumer: Consumer<'static, AdcDacData, BLOCK_BUFFER_SIZE>,
) -> Self {
Self {
stack,
socket: None,
remote: None,
remote: StreamTarget::default().into(),
queue: consumer,
buffer: [0; 1024],
}
@ -230,24 +301,27 @@ impl DataStream {
Ok(())
}
/// Configure the remote endpoint of the stream.
///
/// # Args
/// * `remote` - The destination to send stream data to.
pub fn set_remote(&mut self, remote: SocketAddr) {
// If the remote is identical to what we already have, do nothing.
if let Some(current_remote) = self.remote {
if current_remote == remote {
return;
}
if remote == self.remote {
return;
}
// Open the new remote connection.
self.open(remote).ok();
self.remote = Some(remote);
self.remote = remote;
}
/// Process any data for transmission.
pub fn process(&mut self) {
// If there's no socket available, try to connect to our remote.
if self.socket.is_none() && self.remote.is_some() {
if self.socket.is_none() {
// If we still can't open the remote, continue.
if self.open(self.remote.unwrap()).is_err() {
if self.open(self.remote).is_err() {
// Clear the queue out.
while self.queue.ready() {
self.queue.dequeue();

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@ -113,11 +113,14 @@ where
}
/// Enable live data streaming.
pub fn enable_streaming(&mut self, remote: SocketAddr) -> BlockGenerator {
self.stream.set_remote(remote);
pub fn enable_streaming(&mut self) -> BlockGenerator {
self.generator.take().unwrap()
}
/// Direct the stream to the provided remote target.
///
/// # Args
/// * `remote` - The destination for the streamed data.
pub fn direct_stream(&mut self, remote: SocketAddr) {
if self.generator.is_none() {
self.stream.set_remote(remote);