Better docs and other NATS fixes.

README.md

@@ -2,9 +2,63 @@
 
 A fast way to look up hamming distance hashes.
 
-It operates by connecting to a PostgreSQL database (`DATABASE_URL`), selecting
-every column of a provided query (`DATABASE_QUERY`), subscribing to events
-(`DATABASE_SUBSCRIBE`), and holding everything in a BK tree.
+## Querying
+
+There are two interfaces for querying, both of which can be used simultaneously.
+
+### HTTP
 
 It provides a single API endpoint, `/search` which takes in a `hash` and
-`distance` query parameter to search for matches.
+`distance` query parameter to search for matches. The response looks like this:
+
+```jsonc
+{
+    "hash": 8525958787074004077, // Searched hash
+    "distance": 3, // Maximum search distance
+    "hashes": [ // Results
+        {"hash": 8525958787073873005, "distance": 1}
+    ]
+}
+```
+
+### NATS
+
+It listens on `$NATS_PREFIX.bkapi.search` for a payload like:
+
+```json
+[
+    {"hash": 12345, "distance": 3}
+]
+```
+
+Each input will have a corresponding entry in the response:
+
+```jsonc
+[
+    [ // Results for first input
+        {"hash": 8525958787073873005, "distance": 1}
+    ]
+]
+```
+
+## Initial Load
+
+The initial entries are populated through the databaes query `$DATABASE_QUERY`.
+
+## Listening
+
+It can be configured to listen to PostgreSQL notifications OR with NATS
+messages.
+
+### PostgreSQL
+
+It subscribes to `$DATABASE_SUBSCRIBE`, expecting events to be a JSON object
+containing the hash.
+
+### NATS
+
+It subscribes to `$NATS_PREFIX.bkapi.add`, expecting events to be a JSON object
+containing the hash.
+
+JetStream is used to ensure no hashes are lost without having to reload the
+entire tree on a connection error.

bkapi/src/main.rs

@@ -1,4 +1,4 @@
-use std::{net::SocketAddr, sync::Arc};
+use std::{net::SocketAddr, path::PathBuf, sync::Arc};
 
 use actix_service::Service;
 use actix_web::{
@@ -73,16 +73,16 @@ struct Config {
     database_query: String,
 
     /// If provided, the Postgres notification topic to subscribe to.
-    #[clap(long, env)]
+    #[clap(long, env, required_unless_present = "nats_url")]
     database_subscribe: Option<String>,
 
-    /// The NATS host.
+    /// NATS URLs.
     #[clap(long, env, requires = "nats_prefix")]
-    nats_host: Option<String>,
-    /// The NATS NKEY.
+    nats_url: Option<String>,
+    /// Path to NATS credential file.
     #[clap(long, env)]
-    nats_nkey: Option<String>,
-    /// A prefix to use for NATS subjects.
+    nats_creds: Option<PathBuf>,
+    /// Prefix to use for NATS subjects.
     #[clap(long, env)]
     nats_prefix: Option<String>,
 
@@ -122,14 +122,20 @@ async fn main() {
 
     let (sender, receiver) = futures::channel::oneshot::channel();
 
-    let client = match (config.nats_host.as_deref(), config.nats_nkey.as_deref()) {
+    let client = match (config.nats_url.as_deref(), config.nats_creds.as_deref()) {
         (Some(host), None) => Some(
             async_nats::connect(host)
                 .await
                 .expect_or_log("could not connect to nats with no nkey"),
         ),
-        (Some(host), Some(nkey)) => Some(
-            async_nats::ConnectOptions::with_nkey(nkey.to_string())
+        (Some(host), Some(creds_path)) => Some(
+            async_nats::ConnectOptions::with_credentials_file(creds_path.to_owned())
+                .await
+                .expect_or_log("could not open credentials file")
+                .custom_inbox_prefix(format!(
+                    "_INBOX_{}",
+                    config.nats_prefix.as_deref().unwrap().replace('.', "_")
+                ))
                 .connect(host)
                 .await
                 .expect_or_log("could not connect to nats with nkey"),
@@ -139,26 +145,35 @@ async fn main() {
 
     let tree_clone = tree.clone();
     let config_clone = config.clone();
+    let token_clone = token.clone();
     let mut listener_task = if let Some(subscription) = config.database_subscribe.clone() {
         tracing::info!("starting to listen for payloads from postgres");
-        tokio::spawn(tree::listen_for_payloads_db(
+        tokio::spawn(async move {
+            tree::listen_for_payloads_db(
                 pool,
                 subscription,
-            config.database_query.clone(),
+                config_clone.database_query,
                 tree_clone,
                 sender,
-            token.clone(),
-        ))
+                token_clone,
+            )
+            .await
+            .expect_or_log("could not listen for payloads")
+        })
     } else if let Some(client) = client.clone() {
         tracing::info!("starting to listen for payloads from nats");
-        tokio::spawn(tree::listen_for_payloads_nats(
+        tokio::spawn(async move {
+            tree::listen_for_payloads_nats(
                 config_clone,
                 pool,
                 client,
                 tree_clone,
                 sender,
-            token.clone(),
-        ))
+                token_clone,
+            )
+            .await
+            .expect_or_log("could not listen for payloads")
+        })
     } else {
         panic!("no listener source available");
     };
@@ -311,7 +326,10 @@ async fn search_nats(
 
     let service = client
         .add_service(async_nats::service::Config {
-            name: "bkapi-search".to_string(),
+            name: format!(
+                "{}-bkapi",
+                config.nats_prefix.as_deref().unwrap().replace('.', "-")
+            ),
             version: env!("CARGO_PKG_VERSION").to_string(),
             description: None,
             stats_handler: None,

bkapi/src/tree.rs

@@ -263,6 +263,7 @@ pub(crate) async fn listen_for_payloads_nats(
     // we don't need to start the listener until after it's loaded. This
     // prevents issues with a slow client but still retains every hash.
     let mut seq = stream.cached_info().state.last_sequence;
+    tracing::debug!(seq, "found starting seq");
 
     let create_consumer = |stream: async_nats::jetstream::stream::Stream, start_sequence: u64| async move {
         tracing::info!(start_sequence, "creating consumer");