fix: test failure due to global static (#25287)

This commit changes the write_buffer tests to acquire a lock so that
in tests where we need to have access to NEXT_FILE_ID that it won't
be overwritten since rust tests run as one process and share the
same statics.

While this isn't a problem for Edge as a singular process it is for
our tests. It's a bit unfortunate, but this solution is the easiest
and the locks are not held for long so there's no real big impact
on running these tests.

Closes #25286

influxdb3_write/src/write_buffer/mod.rs

@@ -592,6 +592,7 @@ impl LastCacheManager for WriteBufferImpl {
 impl WriteBuffer for WriteBufferImpl {}
 
 #[cfg(test)]
+#[allow(clippy::await_holding_lock)]
 mod tests {
     use super::*;
     use crate::paths::{CatalogFilePath, SnapshotInfoFilePath};
@@ -609,6 +610,7 @@ mod tests {
     use object_store::local::LocalFileSystem;
     use object_store::memory::InMemory;
     use object_store::{ObjectStore, PutPayload};
+    use parking_lot::{Mutex, MutexGuard};
 
     #[test]
     fn parse_lp_into_buffer() {
@@ -733,6 +735,7 @@ mod tests {
 
     #[tokio::test]
     async fn last_cache_create_and_delete_is_durable() {
+        let lock = lock();
         let (wbuf, _ctx) = setup(
             Time::from_timestamp_nanos(0),
             Arc::new(InMemory::new()),
@@ -744,6 +747,7 @@ mod tests {
             },
         )
         .await;
+        drop(lock);
         let db_name = "db";
         let tbl_name = "table";
         let cache_name = "cache";
@@ -872,6 +876,7 @@ mod tests {
 
     #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
     async fn returns_chunks_across_parquet_and_buffered_data() {
+        let lock = lock();
         let (write_buffer, session_context) = setup(
             Time::from_timestamp_nanos(0),
             Arc::new(InMemory::new()),
@@ -883,6 +888,7 @@ mod tests {
             },
         )
         .await;
+        drop(lock);
 
         let _ = write_buffer
             .write_lp(
@@ -1070,6 +1076,7 @@ mod tests {
 
     #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
     async fn catalog_snapshots_only_if_updated() {
+        let lock = lock();
         let (write_buffer, _ctx) = setup(
             Time::from_timestamp_nanos(0),
             Arc::new(InMemory::new()),
@@ -1081,6 +1088,7 @@ mod tests {
             },
         )
         .await;
+        drop(lock);
 
         let db_name = "foo";
         // do three writes to force a snapshot
@@ -1158,6 +1166,7 @@ mod tests {
         let object_store: Arc<dyn ObjectStore> =
             Arc::new(LocalFileSystem::new_with_prefix(test_helpers::tmp_dir().unwrap()).unwrap());
 
+        let lock = lock();
         // create a snapshot file that will be loaded on initialization of the write buffer:
         // Set NEXT_FILE_ID to a non zero number for the snapshot
         NEXT_FILE_ID.store(500, Ordering::SeqCst);
@@ -1196,6 +1205,7 @@ mod tests {
 
         // Assert that loading the snapshots sets NEXT_FILE_ID to the correct id number
         assert_eq!(NEXT_FILE_ID.load(Ordering::SeqCst), 500);
+        drop(lock);
 
         // there should be one snapshot already, i.e., the one we created above:
         verify_snapshot_count(1, &wbuf.persister).await;
@@ -1619,4 +1629,20 @@ mod tests {
         }
         batches
     }
+
+    /// Lock for the NEXT_FILE_ID data which is set during some of these tests.
+    /// We need to have exclusive access to it to test that it works when loading
+    /// from a snapshot. We lock in most of the calls to setup in this test suite
+    /// where it would cause problems. If running under `cargo-nextest`, return a
+    /// different mutex guard as it does not have this problem due to running
+    /// each test in it's own process
+    fn lock() -> MutexGuard<'static, ()> {
+        static FILE_ID_LOCK: Mutex<()> = Mutex::new(());
+        static DUMMY_LOCK: Mutex<()> = Mutex::new(());
+        if std::env::var("NEXTEST").unwrap_or("0".into()) == "1" {
+            DUMMY_LOCK.lock()
+        } else {
+            FILE_ID_LOCK.lock()
+        }
+    }
 }