fix: disable batch flushing by default (#139)

* fix: disable batch flushing by default

* refactor: update readme and add best practices

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "pyth-agent"
-version = "2.10.3"
+version = "2.10.4"
 edition = "2021"
 
 [[bin]]

README.md

@@ -34,58 +34,22 @@ through the `RUST_LOG` environment variable using the standard
 `error|warn|info|debug|trace`.
 
 #### Plain/JSON logging
-By default, pyth-agent will print plaintext log statements. This can be switched to structured JSON output with `-l json`.
-
-#### Code location in logs
-For debugging purposes, you can specify `-L` to print file/line information with each log statement. This option is disabled by default.
-
-### Key Store Config Migration [v1.x.x LEGACY]
-Pyth agent v2.0.0 introduces a simplified program and mapping key configuration. This breaking change alters how you define program/mapping key options in your agent config:
-```toml
-# Old v1.x.x way
-[primary network]
-key_store.root_path = "/path/to/keystore"
-key_store.publish_keypair_path = "publish_key_pair.json" # Relative path from root_path, "publish_key_pair.json" by default
-key_store.program_key_path = "program_key.json" # Relative path from root_path, "program_key.json" by default
-key_store.mapping_key_path = "mapping_key.json" # Relative path from root_path, "mapping_key.json" by default
-
-# [...]
-
-# New v2.0.0 way
-[primary_network]
-key_store.publish_keypair_path = "/path/to/keypair.json" # The root_path is gone, we specify the full path
-# Not using separate files anymore
-key_store.program_key = "LiteralProgramPubkeyInsideTheConfig" # contents of legacy program_key.json;
-key_store.mapping_key = "LiteralMappingPubkeyInsideTheConfig" # contents of legacy mapping_key.json
-
-# [...]
-
-```
-
-#### Automatic Migration
-If you are upgrading to agent v2.0.0 with an existing config, you can use the provided automatic migrator program:
-```shell
-# Build
-$ cargo build --release
-# Run the migrator, making sure that the key store with previous keys is reachable
-$ target/release/agent-migrate-config -c <existing_config_file>.toml > my_new_config.toml
-```
-
-#### `Could not open {mapping|program|...} key file`
-This error can appear if some of your program/mapping/publish key
-files are not reachable under their `key_store.*` setting values.
-
-Ensure that your current working directory is correct for reaching the
-key store path inside your config. You may also migrate manually by
-changing `key_store.*_key_path` and `key_store.publish_keypair_path`
-options by hand, as described in the config example above.
+Pyth agent will print logs in plaintext in terminal and JSON format in non-terminal environments (e.g. when writing to a file).
 
 ## Run
 `cargo run --release -- --config <your_config.toml>` will build and run the agent in a single step.
 
 ## Publishing API
 A running agent will expose a WebSocket serving the JRPC publishing API documented [here](https://docs.pyth.network/documentation/publish-data/pyth-client-websocket-api). See `config/config.toml` for related settings.
 
+## Best practices
+If your publisher is publishing updates to more than 50 price feeds, it is recommended that you do the following to reduce the connection overhead to the agent:
+- Batch your messages together and send them as a single request to the agent (as an array of messages). The agent will respond to the batch messages
+  with a single response containing an array of individual responses (in the same order). If batching is not possible, you can disable the `instant_flush` option
+  in the configuration file to let agent send the responses every `flush_interval` seconds.
+- Do not use subscribe to the price schedule. Instead, define a schedule on the client side and send the messages based on your own schedule. Ideally
+  you should send price updates as soon as you have them to increase the latency of the data on the Pyth Network.
+
 # Development
 ## Unit Testing
 A collection of Rust unit tests is provided, ran with `cargo test`.

config/config.toml

@@ -14,8 +14,15 @@ listen_address = "127.0.0.1:8910"
 # received from the Price state.
 # notify_price_sched_tx_buffer = 10000
 
+# Whether flush messages and responses to the client immediately. Once disabled the
+# messages will be flushed every `flush_interval_duration`. Disabling it is useful if
+# there are many messages to be sent between the client and the server to avoid overloading
+# the connection.
+# instant_flush = true
+
 # Flush interval for responses and notifications. This is the maximum time the
-# server will wait before flushing the messages to the client.
+# server will wait before flushing the messages to the client. It will have no
+# effect if `instant_flush` is set to true.
 # flush_interval_duration = "50ms"
 
 # Configuration for the primary network this agent will publish data to. In most cases this should be a Pythnet endpoint.

src/agent/pyth/rpc.rs

@@ -18,6 +18,7 @@ use {
         anyhow,
         Result,
     },
+    futures::future::OptionFuture,
     futures_util::{
         stream::{
             SplitSink,
@@ -50,7 +51,10 @@ use {
         sync::Arc,
         time::Duration,
     },
-    tokio::sync::mpsc,
+    tokio::{
+        sync::mpsc,
+        time::Interval,
+    },
     tracing::instrument,
     warp::{
         ws::{
@@ -111,11 +115,18 @@ enum ConnectionError {
     WebsocketConnectionClosed,
 }
 
+#[derive(Debug)]
+enum FlushStrategy {
+    Instant,
+    Interval(Interval),
+}
+
 async fn handle_connection<S>(
     ws_conn: WebSocket,
     state: Arc<S>,
     notify_price_tx_buffer: usize,
     notify_price_sched_tx_buffer: usize,
+    instant_flush: bool,
     flush_interval_duration: Duration,
 ) where
     S: state::Prices,
@@ -129,7 +140,10 @@ async fn handle_connection<S>(
     let (mut notify_price_sched_tx, mut notify_price_sched_rx) =
         mpsc::channel(notify_price_sched_tx_buffer);
 
-    let mut flush_interval = tokio::time::interval(flush_interval_duration);
+    let mut flush_strategy = match instant_flush {
+        true => FlushStrategy::Instant,
+        false => FlushStrategy::Interval(tokio::time::interval(flush_interval_duration)),
+    };
 
     loop {
         if let Err(err) = handle_next(
@@ -140,7 +154,7 @@ async fn handle_connection<S>(
             &mut notify_price_rx,
             &mut notify_price_sched_tx,
             &mut notify_price_sched_rx,
-            &mut flush_interval,
+            &mut flush_strategy,
         )
         .await
         {
@@ -156,6 +170,7 @@ async fn handle_connection<S>(
     }
 }
 
+#[allow(clippy::too_many_arguments)]
 async fn handle_next<S>(
     state: &S,
     ws_tx: &mut SplitSink<WebSocket, Message>,
@@ -164,11 +179,17 @@ async fn handle_next<S>(
     notify_price_rx: &mut mpsc::Receiver<NotifyPrice>,
     notify_price_sched_tx: &mut mpsc::Sender<NotifyPriceSched>,
     notify_price_sched_rx: &mut mpsc::Receiver<NotifyPriceSched>,
-    flush_interval: &mut tokio::time::Interval,
+    flush_strategy: &mut FlushStrategy,
 ) -> Result<()>
 where
     S: state::Prices,
 {
+    let optional_flush_tick: OptionFuture<_> = match flush_strategy {
+        FlushStrategy::Instant => None,
+        FlushStrategy::Interval(interval) => Some(interval.tick()),
+    }
+    .into();
+
     tokio::select! {
         msg = ws_rx.next() => {
             match msg {
@@ -196,9 +217,14 @@ where
             feed_notification(ws_tx, Method::NotifyPriceSched, Some(notify_price_sched))
                 .await
         }
-        _ = flush_interval.tick() => {
+        Some(_) = optional_flush_tick => {
             flush(ws_tx).await
         }
+    }?;
+
+    match flush_strategy {
+        FlushStrategy::Interval(_) => Ok(()),
+        FlushStrategy::Instant => flush(ws_tx).await,
     }
 }
 
@@ -413,6 +439,8 @@ pub struct Config {
     /// Size of the buffer of each Server's channel on which `notify_price_sched` events are
     /// received from the Price state.
     pub notify_price_sched_tx_buffer: usize,
+    /// Whether to flush immediately after sending a message or notification.
+    pub instant_flush:                bool,
     /// Flush interval duration for the notifications.
     #[serde(with = "humantime_serde")]
     pub flush_interval_duration:      Duration,
@@ -424,6 +452,7 @@ impl Default for Config {
             listen_address:               "127.0.0.1:8910".to_string(),
             notify_price_tx_buffer:       10000,
             notify_price_sched_tx_buffer: 10000,
+            instant_flush:                true,
             flush_interval_duration:      Duration::from_millis(50),
         }
     }
@@ -465,6 +494,7 @@ where
                         state,
                         config.notify_price_tx_buffer,
                         config.notify_price_sched_tx_buffer,
+                        config.instant_flush,
                         config.flush_interval_duration,
                     )
                     .await