From fb27b08dda7150eeabd9b3dbf16688172b54fa40 Mon Sep 17 00:00:00 2001
From: "Brian L. Troutwine" <brian.troutwine@datadoghq.com>
Date: Tue, 29 Oct 2024 15:21:28 -0700
Subject: [PATCH] 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>
---
 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,