Log every second a reducer takes to run

crates/client-api-messages/src/energy.rs

@@ -130,7 +130,9 @@ impl fmt::Debug for EnergyBalance {
 pub struct ReducerBudget(u64);
 
 impl ReducerBudget {
-    pub const DEFAULT_BUDGET: Self = ReducerBudget(1_000_000_000_000_000_000);
+    // 1 second of wasm runtime is roughly 2 TeV, so this is
+    // roughly 1 minute of wasm runtime
+    pub const DEFAULT_BUDGET: Self = ReducerBudget(120_000_000_000_000);
 
     pub const ZERO: Self = ReducerBudget(0);
     pub const MAX: Self = ReducerBudget(u64::MAX);

crates/core/src/host/wasmtime/mod.rs

@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::time::Duration;
 
 use anyhow::Context;
 use spacetimedb_paths::server::{ServerDataDir, WasmtimeCacheDir};
@@ -23,12 +24,17 @@ pub struct WasmtimeRuntime {
     linker: Box<Linker<WasmInstanceEnv>>,
 }
 
+const EPOCH_TICK_LENGTH: Duration = Duration::from_millis(10);
+
+const EPOCH_TICKS_PER_SECOND: u64 = Duration::from_secs(1).div_duration_f64(EPOCH_TICK_LENGTH) as u64;
+
 impl WasmtimeRuntime {
     pub fn new(data_dir: Option<&ServerDataDir>) -> Self {
         let mut config = wasmtime::Config::new();
         config
             .cranelift_opt_level(wasmtime::OptLevel::Speed)
             .consume_fuel(true)
+            .epoch_interruption(true)
             .wasm_backtrace_details(wasmtime::WasmBacktraceDetails::Enable);
 
         // Offer a compile-time flag for enabling perfmap generation,
@@ -45,6 +51,16 @@ impl WasmtimeRuntime {
 
         let engine = Engine::new(&config).unwrap();
 
+        let weak_engine = engine.weak();
+        tokio::spawn(async move {
+            let mut interval = tokio::time::interval(EPOCH_TICK_LENGTH);
+            loop {
+                interval.tick().await;
+                let Some(engine) = weak_engine.upgrade() else { break };
+                engine.increment_epoch();
+            }
+        });
+
         let mut linker = Box::new(Linker::new(&engine));
         WasmtimeModule::link_imports(&mut linker).unwrap();
 

crates/core/src/host/wasmtime/wasm_instance_env.rs

@@ -97,7 +97,7 @@ impl WasmInstanceEnv {
             timing_spans: Default::default(),
             reducer_start,
             call_times: CallTimes::new(),
-            reducer_name: String::from(""),
+            reducer_name: String::from("<initializing>"),
             chunk_pool: <_>::default(),
         }
     }
@@ -159,6 +159,16 @@ impl WasmInstanceEnv {
         (args, errors)
     }
 
+    /// Returns the name of the most recent reducer to be run in this environment.
+    pub fn reducer_name(&self) -> &str {
+        &self.reducer_name
+    }
+
+    /// Returns the name of the most recent reducer to be run in this environment.
+    pub fn reducer_start(&self) -> Instant {
+        self.reducer_start
+    }
+
     /// Signal to this `WasmInstanceEnv` that a reducer call is over.
     /// This resets all of the state associated to a single reducer call,
     /// and returns instrumentation records.

crates/core/src/host/wasmtime/wasmtime_module.rs

@@ -1,7 +1,7 @@
 use self::module_host_actor::ReducerOp;
 
 use super::wasm_instance_env::WasmInstanceEnv;
-use super::{Mem, WasmtimeFuel};
+use super::{Mem, WasmtimeFuel, EPOCH_TICKS_PER_SECOND};
 use crate::energy::ReducerBudget;
 use crate::host::instance_env::InstanceEnv;
 use crate::host::wasm_common::module_host_actor::{DescribeError, InitializationError};
@@ -99,8 +99,18 @@ impl module_host_actor::WasmInstancePre for WasmtimeModule {
         let mem = Mem::extract(&instance, &mut store).unwrap();
         store.data_mut().instantiate(mem);
 
+        store.epoch_deadline_callback(|store| {
+            let env = store.data();
+            let database = env.instance_env().replica_ctx.database_identity;
+            let reducer = env.reducer_name();
+            let dur = env.reducer_start().elapsed();
+            tracing::warn!(reducer, ?database, "Wasm has been running for {dur:?}");
+            Ok(wasmtime::UpdateDeadline::Continue(EPOCH_TICKS_PER_SECOND))
+        });
+
         // Note: this budget is just for initializers
         set_store_fuel(&mut store, ReducerBudget::DEFAULT_BUDGET.into());
+        store.set_epoch_deadline(EPOCH_TICKS_PER_SECOND);
 
         for preinit in &func_names.preinits {
             let func = instance.get_typed_func::<(), ()>(&mut store, preinit).unwrap();
@@ -193,6 +203,7 @@ impl module_host_actor::WasmInstance for WasmtimeInstance {
         // otherwise, we'd return something like `used: i128::MAX - u64::MAX`, which is inaccurate.
         set_store_fuel(store, budget.into());
         let original_fuel = get_store_fuel(store);
+        store.set_epoch_deadline(EPOCH_TICKS_PER_SECOND);
 
         // Prepare sender identity and connection ID, as LITTLE-ENDIAN byte arrays.
         let [sender_0, sender_1, sender_2, sender_3] = bytemuck::must_cast(op.caller_identity.to_byte_array());