sof

sof is the SOF observer/runtime crate.

It is built for low-latency Solana data ingest and local runtime-derived signals.

Core responsibilities:

• shred ingestion (direct UDP, relay, optional gossip bootstrap)
• optional shred verification
• dataset reconstruction and transaction extraction
• plugin-driven event hooks for custom logic
• local transaction commitment status tagging (processed / confirmed / finalized) without RPC dependency

At a Glance

• Embed SOF directly inside a Tokio application
• Attach Plugin or RuntimeExtension consumers
• Run with built-in UDP ingress or external kernel-bypass ingress
• Consume local slot/reorg/transaction/account-touch signals
• Use derived-state feed support for restart-safe stateful consumers

Install

cargo add sof

Optional gossip bootstrap support at compile time:

sof = { version = "0.6.1", features = ["gossip-bootstrap"] }

Optional external kernel-bypass ingress support:

sof = { version = "0.6.1", features = ["kernel-bypass"] }

Quick Start

Run the bundled runtime example:

cargo run --release -p sof --example observer_runtime

With gossip bootstrap:

cargo run --release -p sof --example observer_runtime --features gossip-bootstrap

Basic programmatic setup:

#[tokio::main]
async fn main() -> Result<(), sof::runtime::RuntimeError> {
    let setup = sof::runtime::RuntimeSetup::new()
        .with_startup_step_logs(true);
    sof::runtime::run_async_with_setup(&setup).await
}

Runtime API

Embed directly in Tokio:

#[tokio::main]
async fn main() -> Result<(), sof::runtime::RuntimeError> {
    sof::runtime::run_async().await
}

Or use programmatic setup:

use std::net::SocketAddr;

#[tokio::main]
async fn main() -> Result<(), sof::runtime::RuntimeError> {
    let setup = sof::runtime::RuntimeSetup::new()
        .with_bind_addr(SocketAddr::from(([0, 0, 0, 0], 8001)))
        .with_startup_step_logs(true);
    sof::runtime::run_async_with_setup(&setup).await
}

With external kernel-bypass ingress, feed RawPacketBatch values through SOF's ingress queue:

#[tokio::main]
async fn main() -> Result<(), sof::runtime::RuntimeError> {
    let (tx, rx) = sof::runtime::create_kernel_bypass_ingress_queue();
    // Publish batches from your bypass receiver thread:
    // let _ok = tx.send_batch(batch, false);
    // Spawn your kernel-bypass receiver and forward batches into `tx`.
    sof::runtime::run_async_with_kernel_bypass_ingress(rx).await
}

Run the kernel-bypass ingress metrics example for 180 seconds:

SOF_KERNEL_BYPASS_EXAMPLE_DURATION_SECS=180 \
  cargo run --release -p sof --example kernel_bypass_ingress_metrics --features kernel-bypass

Run the same example against live Solana gossip traffic (real chain data):

SOF_KERNEL_BYPASS_EXAMPLE_SOURCE=gossip \
SOF_KERNEL_BYPASS_EXAMPLE_DURATION_SECS=180 \
RUST_LOG=info \
  cargo run --release -p sof --example kernel_bypass_ingress_metrics --features "kernel-bypass gossip-bootstrap"

Run AF_XDP external-ingress example (requires Linux, AF_XDP-capable NIC setup, and privileges to create XDP sockets/programs):

SOF_AF_XDP_IFACE=enp17s0 \
SOF_AF_XDP_EXAMPLE_DURATION_SECS=180 \
  cargo run --release -p sof --example af_xdp_kernel_bypass_ingress_metrics --features "kernel-bypass gossip-bootstrap"

Notes for high-ingest runs:

• The example configures SOF_PORT_RANGE=12000-12100 and SOF_GOSSIP_PORT=8001.
• It defaults live gossip mode to SOF_INGEST_QUEUE_MODE=lockfree with SOF_INGEST_QUEUE_CAPACITY=262144.
• SOF_UDP_DROP_ON_CHANNEL_FULL only applies to SOF's built-in UDP receiver path (non-external ingress).
• Queue mode is configurable with SOF_INGEST_QUEUE_MODE:
  • bounded (default): Tokio bounded channel.
  • unbounded: Tokio unbounded channel (no backpressure drops; memory grows with load).
  • lockfree: lock-free ArrayQueue ring + async wakeups.
• Ring/bounded capacity is configurable with SOF_INGEST_QUEUE_CAPACITY (default 16384).

Plugin Quickstart

use async_trait::async_trait;
use sof::{
    event::TxKind,
    framework::{Plugin, PluginHost, TransactionEvent},
};

#[derive(Clone, Copy, Debug, Default)]
struct NonVoteLogger;

#[async_trait]
impl Plugin for NonVoteLogger {
    fn wants_transaction(&self) -> bool {
        true
    }

    async fn on_transaction(&self, event: TransactionEvent) {
        if event.kind == TxKind::VoteOnly {
            return;
        }
        tracing::info!(slot = event.slot, kind = ?event.kind, "transaction observed");
    }
}

#[tokio::main]
async fn main() -> Result<(), sof::runtime::RuntimeError> {
    let host = PluginHost::builder().add_plugin(NonVoteLogger).build();
    sof::runtime::run_async_with_plugin_host(host).await
}

RuntimeExtension Quickstart

use async_trait::async_trait;
use sof::framework::{
    ExtensionCapability, ExtensionManifest, ExtensionStartupContext, PacketSubscription,
    RuntimeExtension, RuntimeExtensionHost, RuntimePacketSourceKind,
};

#[derive(Debug, Clone, Copy)]
struct IngressExtension;

#[async_trait]
impl RuntimeExtension for IngressExtension {
    async fn on_startup(
        &self,
        _ctx: ExtensionStartupContext,
    ) -> Result<ExtensionManifest, sof::framework::extension::ExtensionStartupError> {
        Ok(ExtensionManifest {
            capabilities: vec![ExtensionCapability::ObserveObserverIngress],
            resources: Vec::new(),
            subscriptions: vec![PacketSubscription {
                source_kind: Some(RuntimePacketSourceKind::ObserverIngress),
                ..PacketSubscription::default()
            }],
        })
    }
}

#[tokio::main]
async fn main() -> Result<(), sof::runtime::RuntimeError> {
    let host = RuntimeExtensionHost::builder()
        .add_extension(IngressExtension)
        .build();
    sof::runtime::run_async_with_extension_host(host).await
}

Plugin Hooks

Current hook set:

• on_raw_packet
• on_shred
• on_dataset
• on_transaction
• on_account_touch
• on_slot_status
• on_reorg
• on_recent_blockhash
• on_cluster_topology (gossip-bootstrap mode)
• on_leader_schedule (gossip-bootstrap mode)

on_transaction events include:

• commitment_status
• confirmed_slot
• finalized_slot

These commitment fields are derived from local shred-stream slot progress (depth-based), not RPC polling.

on_account_touch events include transaction-derived static account-key sets:

• account_keys
• writable_account_keys
• readonly_account_keys
• lookup_table_account_keys

This hook is for account discovery/invalidation. It is not a validator post-write account-update feed.

Derived-State Consumers

SOF also exposes a replayable derived-state feed intended for stateful official extensions and local consumers that need:

• retained feed continuity
• checkpoint persistence
• replay-based recovery after restart or transient failure
• explicit resync/rebuild signaling

Example implementation:

• examples/derived_state_slot_mirror.rs

Design references:

• ../../docs/architecture/derived-state-extension-contract.md
• ../../docs/architecture/derived-state-feed-contract.md

on_slot_status events include local canonical transitions:

• processed
• confirmed
• finalized
• orphaned

Operational Notes

• Hooks are dispatched off the ingest hot path through a bounded queue.
• Queue pressure drops hook events instead of stalling ingest.
• RuntimeExtension WebSocket connectors support full ws:// / wss:// handshake + frame decoding.
• WebSocket close frames emit RuntimePacketEventClass::ConnectionClosed in on_packet_received.
• WebSocket packet events expose websocket_frame_type (Text/Binary/Ping/Pong) for startup-time filtering and runtime routing.
• In gossip mode, SOF runs as an active bounded relay client by default (UDP relay + repair serve), not as an observer-only passive consumer.
• SOF_LIVE_SHREDS_ENABLED=false enables control-plane-only mode.

Examples

• observer_runtime
• observer_with_non_vote_plugin
• observer_with_multiple_plugins
• non_vote_tx_logger
• raydium_contract
• tpu_leader_logger
• runtime_extension_observer_ingress
• runtime_extension_udp_listener
• runtime_extension_shared_stream
• runtime_extension_with_plugins
• runtime_extension_websocket_connector
• derived_state_slot_mirror
• kernel_bypass_ingress_metrics (--features kernel-bypass)

Run kernel-bypass ingress E2E test:

cargo test -p sof --features kernel-bypass --test kernel_bypass_ingress_e2e -- --nocapture

Run any example:

cargo run --release -p sof --example observer_with_multiple_plugins

Docs

• Workspace docs index: ../../docs/README.md
• Architecture docs: ../../docs/architecture/README.md
• Operations docs: ../../docs/operations/README.md
• Reverse-engineering notes: REVERSE_ENGINEERING.md
• Contribution guide: ../../CONTRIBUTING.md