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Reduce Avalanche redundancy and implement traditional fanout (#4174)

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* Reduce Avalanche redundancy and implement traditional fanout

* Revert tiny fanout

* Update diagrams and docs based on review comments
This commit is contained in:
Sagar Dhawan
2019-05-07 13:24:58 -07:00
committed by GitHub
parent 4f3b22d04e
commit 2107e15bd3
8 changed files with 218 additions and 214 deletions
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224
core/src/cluster_info.rs
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@ -51,11 +51,8 @@ use std::time::{Duration, Instant};
pub const FULLNODE_PORT_RANGE: PortRange = (8000, 10_000);
/// The Data plane "neighborhood" size
pub const NEIGHBORHOOD_SIZE: usize = 200;
/// Set whether node capacity should grow as layers are added
pub const GROW_LAYER_CAPACITY: bool = false;
/// The Data plane fanout size, also used as the neighborhood size
pub const DATA_PLANE_FANOUT: usize = 200;
/// milliseconds we sleep for between gossip requests
pub const GOSSIP_SLEEP_MILLIS: u64 = 100;
@ -91,17 +88,17 @@ pub struct Locality {
/// The bounds of the current layer
pub layer_bounds: (usize, usize),
/// The bounds of the next layer
pub child_layer_bounds: Option<(usize, usize)>,
pub next_layer_bounds: Option<(usize, usize)>,
/// The indices of the nodes that should be contacted in next layer
pub child_layer_peers: Vec<usize>,
pub next_layer_peers: Vec<usize>,
}
impl fmt::Debug for Locality {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(
f,
"Packet {{ neighborhood_bounds: {:?}, current_layer: {:?}, child_layer_bounds: {:?} child_layer_peers: {:?} }}",
self.neighbor_bounds, self.layer_ix, self.child_layer_bounds, self.child_layer_peers
"Locality {{ neighborhood_bounds: {:?}, current_layer: {:?}, child_layer_bounds: {:?} child_layer_peers: {:?} }}",
self.neighbor_bounds, self.layer_ix, self.next_layer_bounds, self.next_layer_peers
)
}
}
@ -484,16 +481,8 @@ impl ClusterInfo {
.collect()
}
/// Given a node count, neighborhood size, and an initial fanout (leader -> layer 1), it
/// calculates how many layers are needed and at what index each layer begins.
/// The `grow` parameter is used to determine if the network should 'fanout' or keep
/// layer capacities constant.
pub fn describe_data_plane(
nodes: usize,
fanout: usize,
hood_size: usize,
grow: bool,
) -> (usize, Vec<usize>) {
/// Given a node count and fanout, it calculates how many layers are needed and at what index each layer begins.
pub fn describe_data_plane(nodes: usize, fanout: usize) -> (usize, Vec<usize>) {
let mut layer_indices: Vec<usize> = vec![0];
if nodes == 0 {
(0, vec![])
@ -505,8 +494,8 @@ impl ClusterInfo {
let mut remaining_nodes = nodes - fanout;
layer_indices.push(fanout);
let mut num_layers = 2;
let mut num_neighborhoods = fanout / 2;
let mut layer_capacity = hood_size * num_neighborhoods;
// fanout * num_nodes in a neighborhood, which is also fanout.
let mut layer_capacity = fanout * fanout;
while remaining_nodes > 0 {
if remaining_nodes > layer_capacity {
// Needs more layers.
@ -515,11 +504,8 @@ impl ClusterInfo {
let end = *layer_indices.last().unwrap();
layer_indices.push(layer_capacity + end);
if grow {
// Next layer's capacity
num_neighborhoods *= num_neighborhoods;
layer_capacity = hood_size * num_neighborhoods;
}
// Next layer's capacity
layer_capacity *= fanout;
} else {
//everything will now fit in the layers we have
let end = *layer_indices.last().unwrap();
@ -534,61 +520,64 @@ impl ClusterInfo {
fn localize_item(
layer_indices: &[usize],
hood_size: usize,
fanout: usize,
select_index: usize,
curr_index: usize,
) -> Option<(Locality)> {
let end = layer_indices.len() - 1;
let next = min(end, curr_index + 1);
let value = layer_indices[curr_index];
let localized = select_index >= value && select_index < layer_indices[next];
let mut locality = Locality::default();
let layer_start = layer_indices[curr_index];
// localized if selected index lies within the current layer's bounds
let localized = select_index >= layer_start && select_index < layer_indices[next];
if localized {
let mut locality = Locality::default();
let hood_ix = (select_index - layer_start) / fanout;
match curr_index {
_ if curr_index == 0 => {
locality.layer_ix = 0;
locality.layer_bounds = (0, hood_size);
locality.layer_bounds = (0, fanout);
locality.neighbor_bounds = locality.layer_bounds;
if next == end {
locality.child_layer_bounds = None;
locality.child_layer_peers = vec![];
locality.next_layer_bounds = None;
locality.next_layer_peers = vec![];
} else {
locality.child_layer_bounds =
locality.next_layer_bounds =
Some((layer_indices[next], layer_indices[next + 1]));
locality.child_layer_peers = ClusterInfo::lower_layer_peers(
locality.next_layer_peers = ClusterInfo::next_layer_peers(
select_index,
hood_ix,
layer_indices[next],
layer_indices[next + 1],
hood_size,
fanout,
);
}
}
_ if curr_index == end => {
locality.layer_ix = end;
locality.layer_bounds = (end - hood_size, end);
locality.layer_bounds = (end - fanout, end);
locality.neighbor_bounds = locality.layer_bounds;
locality.child_layer_bounds = None;
locality.child_layer_peers = vec![];
locality.next_layer_bounds = None;
locality.next_layer_peers = vec![];
}
ix => {
let hood_ix = (select_index - value) / hood_size;
locality.layer_ix = ix;
locality.layer_bounds = (value, layer_indices[next]);
locality.layer_bounds = (layer_start, layer_indices[next]);
locality.neighbor_bounds = (
((hood_ix * hood_size) + value),
((hood_ix + 1) * hood_size + value),
((hood_ix * fanout) + layer_start),
((hood_ix + 1) * fanout + layer_start),
);
if next == end {
locality.child_layer_bounds = None;
locality.child_layer_peers = vec![];
locality.next_layer_bounds = None;
locality.next_layer_peers = vec![];
} else {
locality.child_layer_bounds =
locality.next_layer_bounds =
Some((layer_indices[next], layer_indices[next + 1]));
locality.child_layer_peers = ClusterInfo::lower_layer_peers(
locality.next_layer_peers = ClusterInfo::next_layer_peers(
select_index,
hood_ix,
layer_indices[next],
layer_indices[next + 1],
hood_size,
fanout,
);
}
}
@ -599,19 +588,25 @@ impl ClusterInfo {
}
}
/// Given a array of layer indices and another index, returns (as a `Locality`) the layer,
/// layer-bounds and neighborhood-bounds in which the index resides
fn localize(layer_indices: &[usize], hood_size: usize, select_index: usize) -> Locality {
/// Given a array of layer indices and an index of interest, returns (as a `Locality`) the layer,
/// layer-bounds, and neighborhood-bounds in which the index resides
fn localize(layer_indices: &[usize], fanout: usize, select_index: usize) -> Locality {
(0..layer_indices.len())
.find_map(|i| ClusterInfo::localize_item(layer_indices, hood_size, select_index, i))
.find_map(|i| ClusterInfo::localize_item(layer_indices, fanout, select_index, i))
.or_else(|| Some(Locality::default()))
.unwrap()
}
fn lower_layer_peers(index: usize, start: usize, end: usize, hood_size: usize) -> Vec<usize> {
/// Selects a range in the next layer and chooses nodes from that range as peers for the given index
fn next_layer_peers(index: usize, hood_ix: usize, start: usize, fanout: usize) -> Vec<usize> {
// Each neighborhood is only tasked with pushing to `fanout` neighborhoods where each neighborhood contains `fanout` nodes.
let fanout_nodes = fanout * fanout;
// Skip first N nodes, where N is hood_ix * (fanout_nodes)
let start = start + (hood_ix * fanout_nodes);
let end = start + fanout_nodes;
(start..end)
.step_by(hood_size)
.map(|x| x + index % hood_size)
.step_by(fanout)
.map(|x| x + index % fanout)
.collect()
}
@ -1427,31 +1422,28 @@ impl ClusterInfo {
/// 1.1 - If yes, then broadcast to all layer 1 nodes
/// 1 - using the layer 1 index, broadcast to all layer 2 nodes assuming you know neighborhood size
/// 1.2 - If no, then figure out what layer the node is in and who the neighbors are and only broadcast to them
/// 1 - also check if there are nodes in lower layers and repeat the layer 1 to layer 2 logic
/// 1 - also check if there are nodes in the next layer and repeat the layer 1 to layer 2 logic
/// Returns Neighbor Nodes and Children Nodes `(neighbors, children)` for a given node based on its stake (Bank Balance)
pub fn compute_retransmit_peers<S: std::hash::BuildHasher>(
stakes: &HashMap<Pubkey, u64, S>,
cluster_info: &Arc<RwLock<ClusterInfo>>,
fanout: usize,
hood_size: usize,
grow: bool,
) -> (Vec<ContactInfo>, Vec<ContactInfo>) {
let (my_index, peers) = cluster_info.read().unwrap().sorted_peers_and_index(stakes);
//calc num_layers and num_neighborhoods using the total number of nodes
let (num_layers, layer_indices) =
ClusterInfo::describe_data_plane(peers.len(), fanout, hood_size, grow);
let (num_layers, layer_indices) = ClusterInfo::describe_data_plane(peers.len(), fanout);
if num_layers <= 1 {
/* single layer data plane */
(peers, vec![])
} else {
//find my layer
let locality = ClusterInfo::localize(&layer_indices, hood_size, my_index);
let locality = ClusterInfo::localize(&layer_indices, fanout, my_index);
let upper_bound = cmp::min(locality.neighbor_bounds.1, peers.len());
let neighbors = peers[locality.neighbor_bounds.0..upper_bound].to_vec();
let mut children = Vec::new();
for ix in locality.child_layer_peers {
for ix in locality.next_layer_peers {
if let Some(peer) = peers.get(ix) {
children.push(peer.clone());
continue;
@ -2043,78 +2035,72 @@ mod tests {
assert!(val.verify());
}
fn num_layers(nodes: usize, fanout: usize, hood_size: usize, grow: bool) -> usize {
ClusterInfo::describe_data_plane(nodes, fanout, hood_size, grow).0
fn num_layers(nodes: usize, fanout: usize) -> usize {
ClusterInfo::describe_data_plane(nodes, fanout).0
}
#[test]
fn test_describe_data_plane() {
// no nodes
assert_eq!(num_layers(0, 200, 200, false), 0);
assert_eq!(num_layers(0, 200), 0);
// 1 node
assert_eq!(num_layers(1, 200, 200, false), 1);
assert_eq!(num_layers(1, 200), 1);
// 10 nodes with fanout of 2 and hood size of 2
assert_eq!(num_layers(10, 2, 2, false), 5);
// 10 nodes with fanout of 2
assert_eq!(num_layers(10, 2), 3);
// fanout + 1 nodes with fanout of 2 and hood size of 2
assert_eq!(num_layers(3, 2, 2, false), 2);
// 10 nodes with fanout of 4 and hood size of 2 while growing
assert_eq!(num_layers(10, 4, 2, true), 3);
// fanout + 1 nodes with fanout of 2
assert_eq!(num_layers(3, 2), 2);
// A little more realistic
assert_eq!(num_layers(100, 10, 10, false), 3);
assert_eq!(num_layers(100, 10), 2);
// A little more realistic with odd numbers
assert_eq!(num_layers(103, 13, 13, false), 3);
assert_eq!(num_layers(103, 13), 2);
// A little more realistic with just enough for 3 layers
assert_eq!(num_layers(111, 10), 3);
// larger
let (layer_cnt, layer_indices) = ClusterInfo::describe_data_plane(10_000, 10, 10, false);
assert_eq!(layer_cnt, 201);
// distances between index values should be the same since we aren't growing.
let capacity = 10 / 2 * 10;
let (layer_cnt, layer_indices) = ClusterInfo::describe_data_plane(10_000, 10);
assert_eq!(layer_cnt, 4);
// distances between index values should increase by `fanout` for every layer.
let mut capacity = 10 * 10;
assert_eq!(layer_indices[1], 10);
layer_indices[1..layer_indices.len()]
.chunks(2)
.for_each(|x| {
if x.len() == 2 {
assert_eq!(x[1] - x[0], capacity);
}
});
layer_indices[1..].windows(2).for_each(|x| {
if x.len() == 2 {
assert_eq!(x[1] - x[0], capacity);
capacity *= 10;
}
});
// massive
let (layer_cnt, layer_indices) = ClusterInfo::describe_data_plane(500_000, 200, 200, false);
let capacity = 200 / 2 * 200;
let cnt = 500_000 / capacity + 1;
assert_eq!(layer_cnt, cnt);
// distances between index values should be the same since we aren't growing.
let (layer_cnt, layer_indices) = ClusterInfo::describe_data_plane(500_000, 200);
let mut capacity = 200 * 200;
assert_eq!(layer_cnt, 3);
// distances between index values should increase by `fanout` for every layer.
assert_eq!(layer_indices[1], 200);
layer_indices[1..layer_indices.len()]
.chunks(2)
.for_each(|x| {
if x.len() == 2 {
assert_eq!(x[1] - x[0], capacity);
}
});
layer_indices[1..].windows(2).for_each(|x| {
if x.len() == 2 {
assert_eq!(x[1] - x[0], capacity);
capacity *= 200;
}
});
let total_capacity: usize = *layer_indices.last().unwrap();
assert!(total_capacity >= 500_000);
// massive with growth
assert_eq!(num_layers(500_000, 200, 200, true), 3);
}
#[test]
fn test_localize() {
// go for gold
let (_, layer_indices) = ClusterInfo::describe_data_plane(500_000, 200, 200, false);
let (_, layer_indices) = ClusterInfo::describe_data_plane(500_000, 200);
let mut me = 0;
let mut layer_ix = 0;
let locality = ClusterInfo::localize(&layer_indices, 200, me);
assert_eq!(locality.layer_ix, layer_ix);
assert_eq!(
locality.child_layer_bounds,
locality.next_layer_bounds,
Some((layer_indices[layer_ix + 1], layer_indices[layer_ix + 2]))
);
me = 201;
@ -2126,11 +2112,11 @@ mod tests {
layer_indices[layer_ix]
);
assert_eq!(
locality.child_layer_bounds,
locality.next_layer_bounds,
Some((layer_indices[layer_ix + 1], layer_indices[layer_ix + 2]))
);
me = 20_201;
layer_ix = 2;
me = 20_000;
layer_ix = 1;
let locality = ClusterInfo::localize(&layer_indices, 200, me);
assert_eq!(
locality.layer_ix, layer_ix,
@ -2138,13 +2124,13 @@ mod tests {
layer_indices[layer_ix]
);
assert_eq!(
locality.child_layer_bounds,
locality.next_layer_bounds,
Some((layer_indices[layer_ix + 1], layer_indices[layer_ix + 2]))
);
// test no child layer since last layer should have massive capacity
let (_, layer_indices) = ClusterInfo::describe_data_plane(500_000, 200, 200, true);
me = 20_201;
let (_, layer_indices) = ClusterInfo::describe_data_plane(500_000, 200);
me = 40_201;
layer_ix = 2;
let locality = ClusterInfo::localize(&layer_indices, 200, me);
assert_eq!(
@ -2152,23 +2138,23 @@ mod tests {
"layer_indices[layer_ix] is actually {}",
layer_indices[layer_ix]
);
assert_eq!(locality.child_layer_bounds, None);
assert_eq!(locality.next_layer_bounds, None);
}
#[test]
fn test_localize_child_peer_overlap() {
let (_, layer_indices) = ClusterInfo::describe_data_plane(500_000, 200, 200, false);
let (_, layer_indices) = ClusterInfo::describe_data_plane(500_000, 200);
let last_ix = layer_indices.len() - 1;
// sample every 33 pairs to reduce test time
for x in (0..*layer_indices.get(last_ix - 2).unwrap()).step_by(33) {
let me_locality = ClusterInfo::localize(&layer_indices, 200, x);
let buddy_locality = ClusterInfo::localize(&layer_indices, 200, x + 1);
assert!(!me_locality.child_layer_peers.is_empty());
assert!(!buddy_locality.child_layer_peers.is_empty());
assert!(!me_locality.next_layer_peers.is_empty());
assert!(!buddy_locality.next_layer_peers.is_empty());
me_locality
.child_layer_peers
.next_layer_peers
.iter()
.zip(buddy_locality.child_layer_peers.iter())
.zip(buddy_locality.next_layer_peers.iter())
.for_each(|(x, y)| assert_ne!(x, y));
}
}
@ -2177,12 +2163,12 @@ mod tests {
fn test_network_coverage() {
// pretend to be each node in a scaled down network and make sure the set of all the broadcast peers
// includes every node in the network.
let (_, layer_indices) = ClusterInfo::describe_data_plane(25_000, 10, 10, false);
let (_, layer_indices) = ClusterInfo::describe_data_plane(25_000, 10);
let mut broadcast_set = HashSet::new();
for my_index in 0..25_000 {
let my_locality = ClusterInfo::localize(&layer_indices, 10, my_index);
broadcast_set.extend(my_locality.neighbor_bounds.0..my_locality.neighbor_bounds.1);
broadcast_set.extend(my_locality.child_layer_peers);
broadcast_set.extend(my_locality.next_layer_peers);
}
for i in 0..25_000 {