From c0aea479b408be7b842946d7c503a88631851560 Mon Sep 17 00:00:00 2001
From: "Brian L. Troutwine" <brian.troutwine@datadoghq.com>
Date: Thu, 31 Oct 2024 13:22:06 -0700
Subject: [PATCH] Make sure state starts at close to now tick (#1078)

### What does this PR do?

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.
---
 lading/src/generator/file_gen/logrotate_fs.rs       | 7 +++++--
 lading/src/generator/file_gen/logrotate_fs/model.rs | 7 ++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/lading/src/generator/file_gen/logrotate_fs.rs b/lading/src/generator/file_gen/logrotate_fs.rs
index 48308e4b5..92f62007b 100644
--- a/lading/src/generator/file_gen/logrotate_fs.rs
+++ b/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![
diff --git a/lading/src/generator/file_gen/logrotate_fs/model.rs b/lading/src/generator/file_gen/logrotate_fs/model.rs
index b9f931486..0bceaa786 100644
--- a/lading/src/generator/file_gen/logrotate_fs/model.rs
+++ b/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,