flood dissemination

1 files changed, 6 insertions, 2 deletions

diff --git a/src/config/mod.rs b/src/config/mod.rs
index b7c7ff2..25b1c73 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -294,9 +294,9 @@ pub(crate) const OPTIONS: &[OptionSpec] = &[
     option(
         "dissemination",
         Kind::Text,
-        "writers-trees|plumtree",
+        "writers-trees|plumtree|flood",
         Some("writers-trees"),
-        "How a change reaches every member: along writers' trees computed alike on every node from the member list, or by PlumTree (eager links pruned where they deliver twice, grafted where announcements had to bring a change). A genesis node records its own in the document; every node follows what the swarm records, which a protocol writer may change (_continuum/dissemination), and uses its own only where the swarm records none it knows. Default: plumtree with topology hyparview, else writers-trees (docs/topology.md).",
+        "How a change reaches every member: along writers' trees computed alike on every node from the member list, by PlumTree (eager links pruned where they deliver twice, grafted where announcements had to bring a change), or by flooding (every change pushed to every neighbour: the baseline). A genesis node records its own in the document; every node follows what the swarm records, which a protocol writer may change (_continuum/dissemination), and uses its own only where the swarm records none it knows. Default: plumtree with topology hyparview, else writers-trees (docs/topology.md).",
     ),
     option(
         "superseded-writes",
@@ -1581,6 +1581,10 @@ fn warn_combinations(settings: &Settings, set: &dyn Fn(&str) -> bool) {
         (Topology::Hyparview, Dissemination::WritersTrees) => warn!(
             "topology hyparview with dissemination writers-trees: writers' trees need the graph every node shares, which HyParView has none of, so changes pass on by announcements alone, a round and a pull per hop; dissemination plumtree is what goes with it"
         ),
+        (_, Dissemination::Flood) if settings.neighbours > HYPARVIEW_NEIGHBOURS => warn!(
+            neighbours = settings.neighbours,
+            "dissemination flood: every member pushes every change to each of its neighbours, so each link carries it about twice; a baseline to measure against, costly with this many"
+        ),
         (Topology::RingAndPairs, Dissemination::Plumtree) => warn!(
             "dissemination plumtree with topology ring-and-pairs: an experiment; writers' trees, on the graph every node shares, were faster in every scenario benchmarked (docs/topology.md)"
         ),