Make sure state starts at close to now tick

This commit ensures that at startup the state does not start at an
arbitrary tick but at one synchronized with the logrotate_fs. In
practice this comes to the same thing -- today -- but it's an easy
bug to trip on in the future.

Signed-off-by: Brian L. Troutwine <brian.troutwine@datadoghq.com>

Author: blt

lading/src/generator/file_gen/logrotate_fs.rs

@@ -113,8 +113,11 @@ impl Server {
             &config.variant,
         )?;
 
+        let start_time = std::time::Instant::now();
+        let start_time_system = std::time::SystemTime::now();
         let state = model::State::new(
             &mut rng,
+            start_time.elapsed().as_secs(),
             config.bytes_per_second.get_bytes() as u64,
             config.total_rotations,
             config.maximum_bytes_per_log.get_bytes() as u64,
@@ -131,8 +134,8 @@ impl Server {
         let fs = LogrotateFS {
             state: Arc::new(Mutex::new(state)),
             open_files: Arc::new(Mutex::new(HashMap::new())),
-            start_time: std::time::Instant::now(),
-            start_time_system: std::time::SystemTime::now(),
+            start_time,
+            start_time_system,
         };
 
         let options = vec![

lading/src/generator/file_gen/logrotate_fs/model.rs

@@ -347,8 +347,10 @@ pub(crate) enum NodeType {
 impl State {
     /// Create a new instance of `State`.
     #[tracing::instrument(skip(rng, block_cache))]
+    #[allow(clippy::too_many_arguments)]
     pub(crate) fn new<R>(
         rng: &mut R,
+        initial_tick: Tick,
         bytes_per_tick: u64,
         max_rotations: u8,
         max_bytes_per_file: u64,
@@ -374,7 +376,7 @@ impl State {
         let mut state = State {
             nodes,
             root_inode,
-            now: 0,
+            now: initial_tick,
             block_cache,
             max_bytes_per_file,
             max_rotations,
@@ -955,6 +957,7 @@ mod test {
                 1024u64..=500_000u64, // max_bytes_per_file
                 1u8..=4u8,            // max_depth
                 1u16..=16u16,         // concurrent_logs
+                1u64..=1000u64,       // initial_tick
             )
                 .prop_map(
                     |(
@@ -964,6 +967,7 @@ mod test {
                         max_bytes_per_file,
                         max_depth,
                         concurrent_logs,
+                        initial_tick,
                     )| {
                         let mut rng = StdRng::seed_from_u64(seed);
                         let block_cache = block::Cache::fixed(
@@ -976,6 +980,7 @@ mod test {
 
                         State::new(
                             &mut rng,
+                            initial_tick,
                             bytes_per_tick,
                             max_rotations,
                             max_bytes_per_file,