filter: reservoir sample the algo feed

so its not the same static 15 pubkeys

Signed-off-by: William Casarin <jb55@jb55.com>

Cargo.lock

@@ -193,7 +193,7 @@ dependencies = [
  "objc2-foundation 0.3.1",
  "parking_lot",
  "percent-encoding",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
  "x11rb",
 ]
 
@@ -246,7 +246,7 @@ dependencies = [
  "enumflags2",
  "futures-channel",
  "futures-util",
- "rand 0.9.1",
+ "rand 0.9.2",
  "raw-window-handle",
  "serde",
  "serde_repr",
@@ -3542,6 +3542,7 @@ dependencies = [
  "profiling",
  "puffin",
  "puffin_egui",
+ "rand 0.9.2",
  "regex",
  "secp256k1 0.30.0",
  "serde",
@@ -3683,7 +3684,7 @@ dependencies = [
  "nostrdb",
  "notedeck",
  "notedeck_ui",
- "rand 0.9.1",
+ "rand 0.9.2",
  "serde",
  "serde_json",
  "sha2",
@@ -4603,7 +4604,7 @@ dependencies = [
  "bytes",
  "getrandom 0.3.3",
  "lru-slab",
- "rand 0.9.1",
+ "rand 0.9.2",
  "ring",
  "rustc-hash 2.1.1",
  "rustls",
@@ -4657,9 +4658,9 @@ dependencies = [
 
 [[package]]
 name = "rand"
-version = "0.9.1"
+version = "0.9.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9fbfd9d094a40bf3ae768db9361049ace4c0e04a4fd6b359518bd7b73a73dd97"
+checksum = "6db2770f06117d490610c7488547d543617b21bfa07796d7a12f6f1bd53850d1"
 dependencies = [
  "rand_chacha 0.9.0",
  "rand_core 0.9.3",
@@ -6278,7 +6279,7 @@ dependencies = [
  "http",
  "httparse",
  "log",
- "rand 0.9.1",
+ "rand 0.9.2",
  "rustls",
  "rustls-pki-types",
  "sha1",

Cargo.toml

@@ -19,6 +19,7 @@ chrono = "0.4.40"
 base32 = "0.4.0"
 base64 = "0.22.1"
 rmpv = "1.3.0"
+rand = "0.9.2"
 bech32 = { version = "0.11", default-features = false }
 bitflags = "2.5.0"
 dirs = "5.0.1"

crates/notedeck/Cargo.toml

@@ -51,6 +51,7 @@ bitflags = { workspace = true }
 regex = "1"
 chrono = { workspace = true }
 indexmap = {workspace = true}
+rand = {workspace = true}
 crossbeam-channel = "0.5"
 
 [dev-dependencies]

crates/notedeck/src/filter.rs

@@ -289,48 +289,43 @@ pub fn last_n_per_pubkey_from_tags(
     kind: u64,
     notes_per_pubkey: u64,
 ) -> Result<Vec<Filter>, Error> {
+    use rand::Rng;
+
     let mut filters: Vec<Filter> = vec![];
+    let mut rng = rand::rng();
 
-    for tag in note.tags() {
+    // TODO: fix arbitrary MAX_FILTER limit in nostrdb
-        // TODO: fix arbitrary MAX_FILTER limit in nostrdb
+    const LIMIT: usize = 15;
-        if filters.len() == 15 {
-            break;
-        }
 
+    for (i, tag) in note.tags().iter().enumerate() {
         if tag.count() < 2 {
             continue;
         }
 
-        let t = if let Some(t) = tag.get_unchecked(0).variant().str() {
+        let Some("p") = tag.get_str(0) else {
-            t
-        } else {
             continue;
         };
 
-        if t == "p" {
+        let Some(author) = tag.get_id(1) else {
-            let author = if let Some(author) = tag.get_unchecked(1).variant().id() {
+            continue;
-                author
+        };
-            } else {
-                continue;
-            };
 
+        let mk_filter = || {
             let mut filter = Filter::new();
-            filter.start_authors_field()?;
+            let _ = filter.start_authors_field();
-            filter.add_id_element(author)?;
+            let _ = filter.add_id_element(author);
             filter.end_field();
-            filters.push(filter.kinds([kind]).limit(notes_per_pubkey).build());
+            filter.kinds([kind]).limit(notes_per_pubkey).build()
-        } else if t == "t" {
+        };
-            let hashtag = if let Some(hashtag) = tag.get_unchecked(1).variant().str() {
-                hashtag
-            } else {
-                continue;
-            };
 
-            let mut filter = Filter::new();
+        // since we're limited due to a nostrdb bug, we reservoir sample to keep things interesting
-            filter.start_tags_field('t')?;
+        if filters.len() < LIMIT {
-            filter.add_str_element(hashtag)?;
+            filters.push(mk_filter());
-            filter.end_field();
+        } else {
-            filters.push(filter.kinds([kind]).limit(notes_per_pubkey).build());
+            let j = rng.random_range(0..=i);
+            if j < LIMIT {
+                filters[j] = mk_filter();
+            }
         }
     }