oplog state persists timestamp of last snapshot

crates/gitbutler-core/src/ops/state.rs

@@ -1,8 +1,9 @@
-use anyhow::Result;
+use anyhow::{Context, Result};
 use std::{
     fs::File,
     io::Read,
     path::{Path, PathBuf},
+    time::Duration,
 };
 
 use serde::{Deserialize, Serialize};
@@ -14,6 +15,9 @@ use super::OPLOG_FILE_NAME;
 pub struct Oplog {
     /// This is the sha of the last oplog commit
     pub head_sha: Option<String>,
+    /// The time when the last snapshot was created. Seconds since Epoch
+    #[serde(default)]
+    pub modified_at: u64,
 }
 
 pub struct OplogHandle {
@@ -34,7 +38,7 @@ impl OplogHandle {
     pub fn set_oplog_head(&self, sha: String) -> Result<()> {
         let mut oplog = self.read_file()?;
         oplog.head_sha = Some(sha);
-        self.write_file(&oplog)?;
+        self.write_file(oplog)?;
         Ok(())
     }
 
@@ -46,6 +50,14 @@ impl OplogHandle {
         Ok(oplog.head_sha)
     }
 
+    /// Gets the time when the last snapshot was created.
+    ///
+    /// Errors if the file cannot be read or written.
+    pub fn get_modified_at(&self) -> anyhow::Result<Duration> {
+        let oplog = self.read_file()?;
+        Ok(Duration::from_secs(oplog.modified_at))
+    }
+
     /// Reads and parses the state file.
     ///
     /// If the file does not exist, it will be created.
@@ -64,8 +76,13 @@ impl OplogHandle {
         Ok(oplog)
     }
 
-    fn write_file(&self, oplog: &Oplog) -> anyhow::Result<()> {
-        write(self.file_path.as_path(), oplog)
+    fn write_file(&self, oplog: Oplog) -> anyhow::Result<()> {
+        let mut oplog = oplog;
+        let now = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .context("failed to get time since epoch")?;
+        oplog.modified_at = now.as_secs();
+        write(self.file_path.as_path(), &oplog)
     }
 }