Files
fips/src/node/tests/bloom.rs
T
Johnathan Corgan ea9c7f2d8d mesh-size: union all peer filters, not just tree peers
Estimate the OR-union cardinality over self plus every connected peer's
inbound filter, dropping the parent/child tree gating in
compute_mesh_size. Filter propagation is split-horizon, so cross-links
advertise near-complete mesh views; unioning all peers yields the same
set as the tree-only union in steady state (OR dedups overlap and no
filter can over-count) while damping the node-count flap on parent
switches, since dropping the parent no longer collapses the upward leg.
This also removes the estimate's dependence on tree-declaration cache
freshness.

Rename the debug-log child_count to contributor_count, adapt the two
membership-invariant tests to all-peers semantics, and add a test that
the estimate stays stable across a parent drop when a healthy cross-link
is present.
2026-06-09 23:55:48 +00:00

721 lines
27 KiB
Rust

//! Bloom filter integration tests.
//!
//! Verifies that bloom filters are exchanged between all peers and that
//! filter content propagates only through tree edges (tree-only propagation).
use super::spanning_tree::*;
use super::*;
/// Derive the tree edges from the converged spanning tree state.
///
/// For each non-root node, finds the parent relationship and returns
/// the corresponding edge as (child_index, parent_index).
fn get_tree_edges(nodes: &[TestNode]) -> Vec<(usize, usize)> {
let mut edges = Vec::new();
for (i, tn) in nodes.iter().enumerate() {
let ts = tn.node.tree_state();
if !ts.is_root() {
let parent_addr = ts.my_declaration().parent_id();
if let Some(j) = nodes.iter().position(|n| n.node.node_addr() == parent_addr) {
edges.push((i, j));
}
}
}
edges
}
/// Verify that all peer pairs on the given edges have exchanged bloom
/// filters and each peer's inbound filter contains the peer's own
/// node_addr.
fn verify_filter_exchange(nodes: &[TestNode], edges: &[(usize, usize)]) {
for &(i, j) in edges {
let j_addr = *nodes[j].node.node_addr();
let i_addr = *nodes[i].node.node_addr();
// Node i should have a filter from node j
let peer_j = nodes[i]
.node
.get_peer(&j_addr)
.unwrap_or_else(|| panic!("Node {} should have peer {}", i, j));
let filter_from_j = peer_j.inbound_filter().unwrap_or_else(|| {
panic!(
"Node {} should have inbound filter from node {} (addr={})",
i, j, j_addr
)
});
// The filter from j must contain j's own node_addr
assert!(
filter_from_j.contains(&j_addr),
"Node {}'s filter from node {} should contain node {}'s addr",
i,
j,
j
);
// Node j should have a filter from node i
let peer_i = nodes[j]
.node
.get_peer(&i_addr)
.unwrap_or_else(|| panic!("Node {} should have peer {}", j, i));
let filter_from_i = peer_i.inbound_filter().unwrap_or_else(|| {
panic!(
"Node {} should have inbound filter from node {} (addr={})",
j, i, i_addr
)
});
// The filter from i must contain i's own node_addr
assert!(
filter_from_i.contains(&i_addr),
"Node {}'s filter from node {} should contain node {}'s addr",
j,
i,
i
);
}
}
/// Verify propagation along tree edges: each node's filter from a tree
/// peer should contain addresses of the peer's tree neighbors (which
/// were merged into the peer's outgoing filter via tree-only propagation).
fn verify_tree_propagation(nodes: &[TestNode], tree_edges: &[(usize, usize)]) {
let n = nodes.len();
let mut tree_adj = vec![vec![]; n];
for &(i, j) in tree_edges {
tree_adj[i].push(j);
tree_adj[j].push(i);
}
for &(i, j) in tree_edges {
let j_addr = *nodes[j].node.node_addr();
let peer_j = nodes[i].node.get_peer(&j_addr).unwrap();
let filter = peer_j.inbound_filter().unwrap();
// All of j's tree neighbors (except i) should be in j's filter to i
for &neighbor_idx in &tree_adj[j] {
if neighbor_idx == i {
continue; // j excludes i's direction from i's filter
}
let neighbor_addr = *nodes[neighbor_idx].node.node_addr();
assert!(
filter.contains(&neighbor_addr),
"Node {}'s filter from node {} should contain node {}'s tree neighbor {} (addr={})",
i,
j,
j,
neighbor_idx,
neighbor_addr
);
}
}
}
/// 10-node random graph: tree + bloom filter convergence.
#[tokio::test]
async fn test_bloom_filter_10_nodes() {
let edges = generate_random_edges(10, 20, 123);
let mut nodes = run_tree_test(10, &edges, false).await;
verify_tree_convergence(&nodes);
// All peers exchange filters
verify_filter_exchange(&nodes, &edges);
// Content propagation only along tree edges
let tree_edges = get_tree_edges(&nodes);
verify_tree_propagation(&nodes, &tree_edges);
print_filter_cardinality(&nodes);
cleanup_nodes(&mut nodes).await;
}
/// 5-node star: hub node's filter should contain all spokes.
#[tokio::test]
async fn test_bloom_filter_star() {
let edges: Vec<(usize, usize)> = vec![(0, 1), (0, 2), (0, 3), (0, 4)];
let mut nodes = run_tree_test(5, &edges, false).await;
verify_tree_convergence(&nodes);
verify_filter_exchange(&nodes, &edges);
let tree_edges = get_tree_edges(&nodes);
verify_tree_propagation(&nodes, &tree_edges);
// Hub (node 0) sends each spoke a filter containing the other spokes
let hub_addr = *nodes[0].node.node_addr();
for spoke in 1..5 {
let peer = nodes[spoke].node.get_peer(&hub_addr).unwrap();
let filter = peer.inbound_filter().unwrap();
// Filter from hub should contain all OTHER spokes
for (other, other_node) in nodes[1..5].iter().enumerate() {
let other = other + 1; // adjust for slice offset
if other == spoke {
continue;
}
let other_addr = *other_node.node.node_addr();
assert!(
filter.contains(&other_addr),
"Spoke {}'s filter from hub should contain spoke {} (addr={})",
spoke,
other,
other_addr
);
}
}
cleanup_nodes(&mut nodes).await;
}
/// 8-node chain: verify full propagation.
///
/// Chain: 0-1-2-3-4-5-6-7. Each node's outgoing filter is the merge
/// of its own address plus all tree peer inbound filters (excluding the
/// destination peer). This means entries propagate through the entire
/// chain: node 1 merges node 2's filter, which contains node 3's
/// entries, and so on. Both endpoints should see all other nodes.
#[tokio::test]
async fn test_bloom_filter_chain_propagation() {
let edges: Vec<(usize, usize)> = vec![(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 6), (6, 7)];
let mut nodes = run_tree_test(8, &edges, false).await;
verify_tree_convergence(&nodes);
verify_filter_exchange(&nodes, &edges);
let tree_edges = get_tree_edges(&nodes);
verify_tree_propagation(&nodes, &tree_edges);
let addrs: Vec<NodeAddr> = nodes.iter().map(|tn| *tn.node.node_addr()).collect();
// Node 0's filter from node 1 should contain node 1 and its
// immediate neighbor node 2 (node 1 directly merges node 2's filter).
let peer_1 = nodes[0].node.get_peer(&addrs[1]).unwrap();
let filter = peer_1.inbound_filter().unwrap();
assert!(filter.contains(&addrs[1]), "Should contain node 1 (self)");
assert!(
filter.contains(&addrs[2]),
"Should contain node 2 (1-hop neighbor of node 1)"
);
// Entries propagate through the full chain because each
// intermediate node merges its peer's filter into its outgoing
// filter. Verify all nodes are reachable from the endpoints.
for (i, addr) in addrs[2..8].iter().enumerate() {
assert!(
filter.contains(addr),
"Node 0's filter from node 1 should contain node {} \
(chain merge propagation)",
i + 2
);
}
// Verify symmetric: node 7's filter from node 6 should contain all
for i in 0..6 {
let peer_6 = nodes[7].node.get_peer(&addrs[6]).unwrap();
let filter_6 = peer_6.inbound_filter().unwrap();
assert!(
filter_6.contains(&addrs[i]),
"Node 7's filter from node 6 should contain node {} \
(chain merge propagation)",
i
);
}
cleanup_nodes(&mut nodes).await;
}
/// 5-node ring: every node should see all others via peer filters.
///
/// All peers receive filters. Content propagates through the tree
/// (N-1=4 tree edges). Every node is reachable through at least one
/// peer's filter.
#[tokio::test]
async fn test_bloom_filter_ring() {
let edges: Vec<(usize, usize)> = vec![(0, 1), (1, 2), (2, 3), (3, 4), (4, 0)];
let mut nodes = run_tree_test(5, &edges, false).await;
verify_tree_convergence(&nodes);
// All peers (including the non-tree edge) receive filters
verify_filter_exchange(&nodes, &edges);
let tree_edges = get_tree_edges(&nodes);
verify_tree_propagation(&nodes, &tree_edges);
// Every node should be reachable via at least one peer's filter
for i in 0..5 {
for j in 0..5 {
if i == j {
continue;
}
let target_addr = *nodes[j].node.node_addr();
let reachable = nodes[i]
.node
.peers()
.any(|peer| peer.may_reach(&target_addr));
assert!(
reachable,
"Node {} should see node {} as reachable via at least one peer's filter",
i, j
);
}
}
cleanup_nodes(&mut nodes).await;
}
/// Print filter cardinality for all peer relationships (diagnostic helper).
///
/// Useful with `--nocapture` to inspect filter sizes and tree/mesh distinction.
fn print_filter_cardinality(nodes: &[TestNode]) {
println!("\n === Filter Cardinality ===");
for (i, tn) in nodes.iter().enumerate() {
for (j, other) in nodes.iter().enumerate() {
if i == j {
continue;
}
let addr = *other.node.node_addr();
if let Some(peer) = tn.node.get_peer(&addr)
&& let Some(filter) = peer.inbound_filter()
{
let is_tree = tn.node.is_tree_peer(&addr);
println!(
" n{} <- n{}: est={} set_bits={} fill={:.1}% tree={}",
i,
j,
match filter.estimated_count(f64::INFINITY) {
Some(n) => format!("{:.1}", n),
None => "saturated".to_string(),
},
filter.count_ones(),
filter.fill_ratio() * 100.0,
is_tree,
);
}
}
}
}
/// Compute the set of node indices in a subtree rooted at `subtree_root`,
/// given a tree adjacency list and the actual root of the whole tree.
fn collect_subtree(
subtree_root: usize,
parent: Option<usize>,
tree_adj: &[Vec<usize>],
) -> Vec<usize> {
let mut result = vec![subtree_root];
for &neighbor in &tree_adj[subtree_root] {
if Some(neighbor) != parent {
result.extend(collect_subtree(neighbor, Some(subtree_root), tree_adj));
}
}
result
}
/// 7-node tree: verify split-horizon asymmetry between upward and downward filters.
///
/// Creates a pure tree topology and verifies that:
/// - Upward filters (child→parent) contain only the child's subtree
/// - Downward filters (parent→child) contain only the complement
/// - Cardinality estimates match expected subtree sizes
///
/// The tree structure formed depends on which node gets the lowest NodeAddr
/// (becomes root), but the split-horizon property holds regardless.
#[tokio::test]
async fn test_bloom_filter_split_horizon() {
// Pure tree: 7 nodes, 6 edges
let edges: Vec<(usize, usize)> = vec![(0, 1), (0, 2), (1, 3), (1, 4), (2, 5), (5, 6)];
let mut nodes = run_tree_test(7, &edges, false).await;
verify_tree_convergence(&nodes);
verify_filter_exchange(&nodes, &edges);
let tree_edges = get_tree_edges(&nodes);
verify_tree_propagation(&nodes, &tree_edges);
let addrs: Vec<NodeAddr> = nodes.iter().map(|tn| *tn.node.node_addr()).collect();
// Build the actual tree adjacency from converged state
let n = nodes.len();
let mut tree_adj = vec![vec![]; n];
for &(child, parent) in &tree_edges {
tree_adj[child].push(parent);
tree_adj[parent].push(child);
}
print_filter_cardinality(&nodes);
// For each tree edge (child, parent), verify split-horizon:
// - child's filter to parent contains child's subtree only
// - parent's filter to child contains the complement only
for &(child_idx, parent_idx) in &tree_edges {
let child_subtree = collect_subtree(child_idx, Some(parent_idx), &tree_adj);
let complement: Vec<usize> = (0..n).filter(|i| !child_subtree.contains(i)).collect();
// --- Upward filter: child → parent ---
// This is stored as parent's inbound filter from child
let filter_up = nodes[parent_idx]
.node
.get_peer(&addrs[child_idx])
.unwrap()
.inbound_filter()
.unwrap();
// Should contain all nodes in child's subtree
for &idx in &child_subtree {
assert!(
filter_up.contains(&addrs[idx]),
"Upward filter (n{}→n{}): should contain subtree member n{} but doesn't",
child_idx,
parent_idx,
idx
);
}
// Should NOT contain nodes in the complement
for &idx in &complement {
assert!(
!filter_up.contains(&addrs[idx]),
"Upward filter (n{}→n{}): should NOT contain complement member n{} but does",
child_idx,
parent_idx,
idx
);
}
// Cardinality should match subtree size
let up_est = filter_up
.estimated_count(f64::INFINITY)
.expect("upward filter should not be saturated in tree convergence test");
assert!(
(up_est - child_subtree.len() as f64).abs() < 1.5,
"Upward filter (n{}→n{}): expected ~{} entries, got {:.1}",
child_idx,
parent_idx,
child_subtree.len(),
up_est
);
// --- Downward filter: parent → child ---
// This is stored as child's inbound filter from parent
let filter_down = nodes[child_idx]
.node
.get_peer(&addrs[parent_idx])
.unwrap()
.inbound_filter()
.unwrap();
// Should contain all nodes in the complement
for &idx in &complement {
assert!(
filter_down.contains(&addrs[idx]),
"Downward filter (n{}→n{}): should contain complement member n{} but doesn't",
parent_idx,
child_idx,
idx
);
}
// Should NOT contain nodes in child's subtree (except: split-horizon
// excludes the child's direction, but child itself is NOT in parent's
// outgoing filter to child — parent merges child's filter into filters
// for OTHER peers, not back to child)
for &idx in &child_subtree {
assert!(
!filter_down.contains(&addrs[idx]),
"Downward filter (n{}→n{}): should NOT contain subtree member n{} but does",
parent_idx,
child_idx,
idx
);
}
// Cardinality should match complement size
let down_est = filter_down
.estimated_count(f64::INFINITY)
.expect("downward filter should not be saturated in tree convergence test");
assert!(
(down_est - complement.len() as f64).abs() < 1.5,
"Downward filter (n{}→n{}): expected ~{} entries, got {:.1}",
parent_idx,
child_idx,
complement.len(),
down_est
);
// Together, subtree + complement = all nodes
assert_eq!(
child_subtree.len() + complement.len(),
n,
"Subtree + complement should cover all {} nodes",
n
);
}
cleanup_nodes(&mut nodes).await;
}
/// Each peer's inbound filter contributes exactly once, independent of
/// tree-declaration state.
///
/// Under all-peers union semantics there is no parent/child gating and no
/// `peer_declaration` lookup, so a stale or contradictory declaration
/// cache cannot cause a peer's bloom cardinality to be folded twice. This
/// retains the spirit of the old parent-double-count regression: we set up
/// the same stale-cache scenario (the cached `peer_declaration(P)` still
/// names US as P's parent) and assert the estimate reflects each filter
/// counted once, not the double-count fingerprint.
#[test]
fn compute_mesh_size_counts_each_peer_filter_once() {
use crate::bloom::BloomFilter;
use crate::peer::ActivePeer;
use crate::tree::ParentDeclaration;
let mut node = make_node();
let my_addr = *node.tree_state().my_node_addr();
// Generate a parent identity strictly less than my_addr so the
// tree_state defensive check (my_node_addr > parent_root) accepts
// the extension; otherwise recompute_coords would demote us back
// to self-root and is_root() would stay true.
let (parent_identity, parent_addr) = loop {
let candidate = make_peer_identity();
let addr = *candidate.node_addr();
if addr < my_addr {
break (candidate, addr);
}
};
let mut parent_peer = ActivePeer::new(parent_identity, LinkId::new(1), 0);
let mut parent_filter = BloomFilter::new();
for i in 0..5u8 {
let mut bytes = [0u8; 16];
bytes[0] = 0x80 | i; // distinct namespace
parent_filter.insert(&NodeAddr::from_bytes(bytes));
}
parent_peer.update_filter(parent_filter, 1, 0);
node.peers.insert(parent_addr, parent_peer);
// Inject legitimate child Q with a 3-entry inbound filter.
let child_identity = make_peer_identity();
let child_addr = *child_identity.node_addr();
let mut child_peer = ActivePeer::new(child_identity, LinkId::new(2), 0);
let mut child_filter = BloomFilter::new();
for i in 0..3u8 {
let mut bytes = [0u8; 16];
bytes[0] = 0xC0 | i;
child_filter.insert(&NodeAddr::from_bytes(bytes));
}
child_peer.update_filter(child_filter, 1, 0);
node.peers.insert(child_addr, child_peer);
// Seed parent ancestry first so recompute_coords can extend it and
// flip is_root() to false; child ancestry is for completeness.
let parent_ancestry = crate::tree::TreeCoordinate::root_with_meta(parent_addr, 1, 1);
let child_ancestry = crate::tree::TreeCoordinate::root_with_meta(child_addr, 1, 1);
// Inject the stale-cache scenario: peer_declaration(P) still names
// US (M) as P's parent (the pre-switch advert that the cache hasn't
// refreshed yet). Q is a legitimate child also naming M as parent.
// Under all-peers semantics these declarations no longer affect the
// estimate at all.
let parent_decl_stale = ParentDeclaration::new(parent_addr, my_addr, 1, 1);
let child_decl = ParentDeclaration::new(child_addr, my_addr, 1, 1);
node.tree_state_mut()
.update_peer(parent_decl_stale, parent_ancestry);
node.tree_state_mut()
.update_peer(child_decl, child_ancestry);
// Switch our parent to P and recompute coords so root flips off self.
node.tree_state_mut().set_parent(parent_addr, 2, 1);
node.tree_state_mut().recompute_coords();
assert!(
!node.tree_state().is_root(),
"test setup broken: node should not be its own root after parent switch"
);
node.compute_mesh_size();
let estimate = node
.estimated_mesh_size()
.expect("estimator should produce a value with filter data present");
// Each filter counted once: 1 (self) + 5 (P) + 3 (Q) = 9.
// A double-count of P (the old declaration-cache bug fingerprint)
// would land near 1 + 2*5 + 3 = 14.
// The estimator's log-based math rounds, so allow +/-1 tolerance.
let diff = (estimate as i64 - 9).abs();
assert!(
diff <= 1,
"expected mesh-size estimate ~9 (1+5+3), got {} (double-count fingerprint is ~14)",
estimate
);
}
/// Overlapping peer inbound filters must be OR-unioned, not summed.
///
/// Two connected peers share several NodeAddrs (plus a few distinct ones
/// each). The naive sum of per-filter cardinalities would over-count the
/// shared entries; the union estimate must instead approximate the number
/// of *distinct* addresses across both filters (plus self). Under all-peers
/// semantics the union folds in every connected peer regardless of tree
/// role, so no parent/child wiring is needed — this asserts the
/// overlap-dedup property directly on the union result that
/// `estimated_mesh_size` carries.
#[test]
fn compute_mesh_size_unions_overlapping_filters() {
use crate::bloom::BloomFilter;
use crate::peer::ActivePeer;
let mut node = make_node();
// Build the set of addresses. SHARED appear in both filters; the
// distinct sets appear in only one each.
let mk = |hi: u8, lo: u8| {
let mut bytes = [0u8; 16];
bytes[0] = hi;
bytes[1] = lo;
NodeAddr::from_bytes(bytes)
};
let shared: Vec<NodeAddr> = (0..6u8).map(|i| mk(0x10, i)).collect();
let peer_a_only: Vec<NodeAddr> = (0..3u8).map(|i| mk(0x20, i)).collect();
let peer_b_only: Vec<NodeAddr> = (0..3u8).map(|i| mk(0x30, i)).collect();
// Distinct addresses across the union: shared + peer_a_only +
// peer_b_only + self = 6 + 3 + 3 + 1 = 13. The naive sum of the two
// filters' cardinalities would be (6+3) + (6+3) + 1 = 19.
let distinct = shared.len() + peer_a_only.len() + peer_b_only.len() + 1; // 13
let naive_sum = (shared.len() + peer_a_only.len()) + (shared.len() + peer_b_only.len()) + 1; // 19
// Peer A with shared + peer_a_only.
let peer_a_identity = make_peer_identity();
let peer_a_addr = *peer_a_identity.node_addr();
let mut peer_a = ActivePeer::new(peer_a_identity, LinkId::new(1), 0);
let mut filter_a = BloomFilter::new();
for addr in shared.iter().chain(peer_a_only.iter()) {
filter_a.insert(addr);
}
peer_a.update_filter(filter_a, 1, 0);
node.peers.insert(peer_a_addr, peer_a);
// Peer B with a filter that overlaps A's on `shared`.
let peer_b_identity = make_peer_identity();
let peer_b_addr = *peer_b_identity.node_addr();
let mut peer_b = ActivePeer::new(peer_b_identity, LinkId::new(2), 0);
let mut filter_b = BloomFilter::new();
for addr in shared.iter().chain(peer_b_only.iter()) {
filter_b.insert(addr);
}
peer_b.update_filter(filter_b, 1, 0);
node.peers.insert(peer_b_addr, peer_b);
node.compute_mesh_size();
let estimate =
node.estimated_mesh_size()
.expect("estimator should produce a value with filter data present") as i64;
// The union estimate should approximate the distinct count (13), not
// the naive sum (19). Bloom cardinality estimation rounds, so allow a
// small absolute tolerance, and require we are clearly below the sum.
let diff = (estimate - distinct as i64).abs();
assert!(
diff <= 2,
"expected union mesh-size estimate ~{} (distinct addrs), got {}",
distinct,
estimate
);
assert!(
estimate < naive_sum as i64,
"estimate {} must be below the naive sum {} (overlap should be deduplicated)",
estimate,
naive_sum
);
}
/// Flap-damping: the estimate survives a parent switch when a healthy
/// cross-link carries the upward coverage.
///
/// Under the old tree-only union, the upward leg of the estimate hinged
/// entirely on the current parent's filter; dropping the parent (a parent
/// switch transient, before the new parent's filter converges) collapsed
/// the estimate to self + children. Under all-peers semantics a cross-link
/// peer whose split-horizon `inbound_filter` carries the same upward
/// coverage keeps the union nearly intact across the drop. This builds a
/// node with a parent and one healthy cross-link, records the estimate,
/// removes the parent, and asserts the estimate does not collapse.
#[test]
fn compute_mesh_size_stable_across_parent_drop_with_cross_link() {
use crate::bloom::BloomFilter;
use crate::peer::ActivePeer;
let mut node = make_node();
let mk = |hi: u8, lo: u8| {
let mut bytes = [0u8; 16];
bytes[0] = hi;
bytes[1] = lo;
NodeAddr::from_bytes(bytes)
};
// Upward coverage: the set of addresses reachable through the rest of
// the mesh (everything outside our local subtree). Both the parent and
// a healthy cross-link advertise this under split-horizon propagation.
let upward: Vec<NodeAddr> = (0..12u8).map(|i| mk(0x40, i)).collect();
// The cross-link additionally knows a couple of addresses of its own.
let cross_extra: Vec<NodeAddr> = (0..2u8).map(|i| mk(0x50, i)).collect();
// Parent P: carries the upward coverage.
let parent_identity = make_peer_identity();
let parent_addr = *parent_identity.node_addr();
let mut parent_peer = ActivePeer::new(parent_identity, LinkId::new(1), 0);
let mut parent_filter = BloomFilter::new();
for addr in &upward {
parent_filter.insert(addr);
}
parent_peer.update_filter(parent_filter, 1, 0);
node.peers.insert(parent_addr, parent_peer);
// Cross-link X: a non-tree peer whose split-horizon filter also carries
// the upward coverage (plus a little of its own).
let cross_identity = make_peer_identity();
let cross_addr = *cross_identity.node_addr();
let mut cross_peer = ActivePeer::new(cross_identity, LinkId::new(2), 0);
let mut cross_filter = BloomFilter::new();
for addr in upward.iter().chain(cross_extra.iter()) {
cross_filter.insert(addr);
}
cross_peer.update_filter(cross_filter, 1, 0);
node.peers.insert(cross_addr, cross_peer);
// Baseline estimate with both peers present.
node.compute_mesh_size();
let before =
node.estimated_mesh_size()
.expect("estimator should produce a value with filter data present") as i64;
// Simulate a parent switch transient: the old parent is dropped before
// the new parent's filter has converged. The cross-link remains.
node.peers.remove(&parent_addr);
node.compute_mesh_size();
let after = node
.estimated_mesh_size()
.expect("estimator should still produce a value via the cross-link") as i64;
// The estimate must not collapse: the cross-link still holds the upward
// coverage. Old tree-only behavior would have lost the entire upward
// leg (~12 addrs) and dropped to roughly self alone. Allow a small
// tolerance for bloom rounding and the cross-link's couple extra bits.
let diff = (before - after).abs();
assert!(
diff <= 2,
"mesh-size estimate collapsed across parent drop: before={before}, after={after} \
(cross-link should preserve upward coverage)"
);
}
/// 100-node random graph: bloom filter exchange at scale.
#[tokio::test]
async fn test_bloom_filter_convergence_100_nodes() {
let _guard = lock_large_network_test().await;
const NUM_NODES: usize = 100;
const TARGET_EDGES: usize = 250;
const SEED: u64 = 42;
let edges = generate_random_edges(NUM_NODES, TARGET_EDGES, SEED);
let mut nodes = run_tree_test(NUM_NODES, &edges, false).await;
verify_tree_convergence(&nodes);
verify_filter_exchange(&nodes, &edges);
let tree_edges = get_tree_edges(&nodes);
verify_tree_propagation(&nodes, &tree_edges);
print_filter_cardinality(&nodes);
cleanup_nodes(&mut nodes).await;
}