add defaults for usual performance config values

.gitignore

@@ -3,3 +3,5 @@ data*
 target
 .idea
 *.swp
+/*.yaml
+/*.yml

lib/src/config/ethshadow.rs

@@ -376,6 +376,15 @@ impl EthShadowConfig {
         self.clients.entry(name.into()).or_insert(Box::new(client));
     }
 
+    pub fn minimum_latency(&self) -> Duration {
+        self.locations
+            .values()
+            .flat_map(|loc| loc.latency_to.values())
+            .map(|latency| latency.into_inner())
+            .min()
+            .expect("latencies should be specified at this point")
+    }
+
     pub fn desugar_nodes(&self) -> Result<Vec<Node>, Error> {
         let mut result = vec![];
 

lib/src/config/shadow.rs

@@ -4,6 +4,7 @@ use serde::Serialize;
 use serde_yaml::mapping::IterMut;
 use serde_yaml::{to_value, Mapping, Value};
 use std::collections::HashMap;
+use std::time::Duration;
 
 /// A light wrapper around a yaml mapping representing the root of a shadow config with some useful
 /// setters and getters
@@ -30,6 +31,22 @@ pub struct Process {
 }
 
 impl ShadowConfig {
+    pub fn general_mut(&mut self) -> Result<&mut Mapping, Error> {
+        self.0
+            .entry("general".into())
+            .or_insert(Mapping::new().into())
+            .as_mapping_mut()
+            .ok_or_else(|| Error::ExpectedOtherType("general".into()))
+    }
+
+    pub fn experimental_mut(&mut self) -> Result<&mut Mapping, Error> {
+        self.0
+            .entry("experimental".into())
+            .or_insert(Mapping::new().into())
+            .as_mapping_mut()
+            .ok_or_else(|| Error::ExpectedOtherType("experimental".into()))
+    }
+
     pub fn seed(&self) -> u64 {
         self.0
             .get("general")
@@ -83,6 +100,28 @@ impl ShadowConfig {
                 .map(|h| h.iter_mut()),
         })
     }
+
+    pub fn apply_defaults(&mut self, runahead: Duration) -> Result<(), Error> {
+        let general = self.general_mut()?;
+        general
+            .entry("model_unblocked_syscall_latency".into())
+            .or_insert(Value::Bool(true));
+        general
+            .entry("heartbeat_interval".into())
+            .or_insert_with(|| Value::String("1m".into()));
+        let experimental = self.experimental_mut()?;
+        // todo: warn user if they override runahead with a value larger than the min latency
+        experimental
+            .entry("runahead".into())
+            .or_insert_with(|| format!("{}ns", runahead.as_nanos()).into());
+        experimental
+            .entry("use_memory_manager".into())
+            .or_insert(Value::Bool(true));
+        experimental
+            .entry("host_heartbeat_interval".into())
+            .or_insert_with(|| Value::String("1m".into()));
+        Ok(())
+    }
 }
 
 pub struct HostsMut<'a> {

lib/src/lib.rs

@@ -60,6 +60,7 @@ pub fn generate<T: TryInto<FullConfig, Error = Error>>(
         mut shadow_config,
     } = config.try_into()?;
     ethshadow_config.add_default_builtins();
+    shadow_config.apply_defaults(ethshadow_config.minimum_latency())?;
 
     create_dir(&output_path).map_err(|e| match e.kind() {
         ErrorKind::AlreadyExists => Error::OutputFolderExists,