feat: persist job counter across restarts

daemon/Cargo.toml

@@ -14,6 +14,7 @@ path = "main.rs"
 doc = false
 
 [dependencies]
+atomicwrites = "0.4.1"
 clap = { version = "4.2.7", features = ["derive", "env"] }
 env_logger.workspace = true
 log.workspace = true
@@ -24,3 +25,4 @@ zinnia_runtime = { workspace = true }
 
 [dev-dependencies]
 pretty_assertions = { workspace = true }
+tempfile = "3.5.0"

daemon/main.rs

@@ -1,6 +1,8 @@
 mod args;
+mod state;
 mod station_reporter;
 
+use std::path::PathBuf;
 use std::rc::Rc;
 use std::time::Duration;
 
@@ -36,6 +38,9 @@ async fn run(config: CliArgs) -> Result<()> {
         ));
     }
 
+    let state_file = PathBuf::from(config.state_root).join("state.json");
+    log::debug!("Using state file: {}", state_file.display());
+
     log_info_activity("Module Runtime started.");
 
     let file = &config.files[0];
@@ -56,6 +61,7 @@ async fn run(config: CliArgs) -> Result<()> {
         ),
         wallet_address: config.wallet_address,
         reporter: Rc::new(StationReporter::new(
+            state_file,
             Duration::from_millis(200),
             module_name.into(),
         )),

daemon/state.rs

@@ -0,0 +1,89 @@
+use atomicwrites::{AtomicFile, OverwriteBehavior};
+use serde::{Deserialize, Serialize};
+use std::io::Write;
+use std::path::Path;
+use zinnia_runtime::anyhow::{self, Context, Result};
+
+#[derive(Serialize, Deserialize, Debug, Default)]
+pub struct State {
+    pub total_jobs_completed: u64,
+}
+
+impl State {
+    pub fn load(state_file: &Path) -> Result<Self> {
+        log::debug!("Loading initial state from {}", state_file.display());
+        match std::fs::read_to_string(state_file) {
+            Err(err) => match err.kind() {
+                std::io::ErrorKind::NotFound => {
+                    let state = State::default();
+                    log::debug!("State file not found, returning {state:?}");
+                    Ok(state)
+                }
+                _ => Err(anyhow::Error::new(err).context(format!(
+                    "Cannot load initial state from {}",
+                    state_file.display()
+                ))),
+            },
+            Ok(data) => {
+                let state = serde_json::from_str::<State>(&data).with_context(|| {
+                    format!("Cannot parse initial state from {}", state_file.display())
+                })?;
+                log::debug!("Loaded initial state: {state:?}");
+                Ok(state)
+            }
+        }
+    }
+
+    pub fn store(&self, state_file: &Path) -> Result<()> {
+        let payload = serde_json::to_string_pretty(self).context("Cannot serialize state")?;
+
+        let mut write_result = AtomicFile::new(state_file, OverwriteBehavior::AllowOverwrite)
+            .write(|f| f.write_all(payload.as_bytes()));
+
+        if let Err(atomicwrites::Error::Internal(err)) = &write_result {
+            if err.kind() == std::io::ErrorKind::NotFound {
+                if let Some(parent) = state_file.parent() {
+                    std::fs::create_dir_all(parent).with_context(|| {
+                        format!("Cannot create state directory {}", parent.display(),)
+                    })?;
+                    write_result = AtomicFile::new(state_file, OverwriteBehavior::AllowOverwrite)
+                        .write(|f| f.write_all(payload.as_bytes()));
+                }
+            }
+        }
+
+        write_result.with_context(|| format!("Cannot write state to {}", state_file.display()))?;
+        log::debug!("State stored in {}", state_file.display());
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use pretty_assertions::assert_eq;
+    use tempfile::tempdir;
+    use zinnia_runtime::anyhow::Result;
+
+    #[test]
+    fn loads_empty_state() -> Result<()> {
+        let state_dir = tempdir()?;
+        let state_file = state_dir.path().join("state.json");
+        let loaded = State::load(&state_file)?;
+        assert_eq!(loaded.total_jobs_completed, 0, "total_jobs_completed");
+        Ok(())
+    }
+
+    #[test]
+    fn creates_missing_directories() -> Result<()> {
+        let state_dir = tempdir()?;
+        let state_file = state_dir.path().join("subdir").join("state.json");
+        let state = State {
+            total_jobs_completed: 1,
+        };
+        state.store(&state_file)?;
+        let loaded = State::load(&state_file)?;
+        assert_eq!(loaded.total_jobs_completed, 1);
+        Ok(())
+    }
+}