storage: Cache VFS RNG for crash simulation

We'll avoid re-initializing the RNG and instead cache it in a
thread-local.

server/src/engine/macros.rs

@@ -401,7 +401,7 @@ macro_rules! local {
 }
 
 macro_rules! local_mut {
-    ($ident:ident, $call:expr) => {{
+    ($ident:expr, $call:expr) => {{
         #[inline(always)]
         fn _f<T, U>(v: &::std::cell::RefCell<T>, f: impl FnOnce(&mut T) -> U) -> U {
             f(&mut *v.borrow_mut())

server/src/engine/storage/common/interface/vfs.rs

@@ -50,6 +50,7 @@ pub mod vfs_utils {
     }
     local!(
         static RANDOM_WRITE_CRASH: WriteCrashKind = WriteCrashKind::None;
+        pub(super) static RNG: Option<rand::rngs::ThreadRng> = None;
     );
     /// WARNING: A random write crash automatically degrades to a [`WriteCrashKind::Zero`] as soon as it completes
     /// to prevent any further data writes (due to retries in
@@ -204,9 +205,18 @@ impl VFile {
                 Ok(bytes.len() as _)
             }
             vfs_utils::WriteCrashKind::Random => {
+                let actual_write_length = local_mut!(vfs_utils::RNG, |rng| {
+                    match rng {
+                        Some(ref mut rng) => test_utils::random_number(0, bytes.len(), rng),
+                        None => {
+                            let mut rng_ = rand::thread_rng();
+                            let r = test_utils::random_number(0, bytes.len(), &mut rng_);
+                            *rng = Some(rng_);
+                            r
+                        }
+                    }
+                });
                 // write some random part of the buffer into this file
-                let mut rng = rand::thread_rng();
-                let actual_write_length = test_utils::random_number(0, bytes.len(), &mut rng);
                 if self.pos + actual_write_length > self.data.len() {
                     self.data.resize(self.pos + actual_write_length, 0);
                 }

server/src/engine/storage/v2/raw/journal/raw/tests/recovery.rs

@@ -1531,6 +1531,7 @@ fn emulate_failure_for_rollback(
         post_rollback(&db);
         RawJournalWriter::close_driver(&mut jrnl).unwrap();
     }
+    FileSystem::remove_file(journal_id).unwrap();
 }
 
 #[test]
@@ -1576,41 +1577,45 @@ fn rollback_write_zero_nonempty_log() {
 
 #[test]
 fn rollback_random_write_failure_empty_log() {
-    emulate_failure_for_rollback(
-        "rollback_random_write_failure_empty_log",
-        |db, jrnl| {
-            vfs_utils::debug_enable_random_write_crash();
-            let r = db.push(jrnl, "hello, world");
-            vfs_utils::debug_disable_write_crash();
-            r
-        },
-        |e| match e.kind() {
-            ErrorKind::IoError(io) if io.kind() == IoErrorKind::WriteZero => {}
-            unexpected => panic!("expected write zero, got {unexpected:?}"),
-        },
-        |db| assert_eq!(db.data().len(), 0),
-    );
+    for _ in 0..100 {
+        emulate_failure_for_rollback(
+            "rollback_random_write_failure_empty_log",
+            |db, jrnl| {
+                vfs_utils::debug_enable_random_write_crash();
+                let r = db.push(jrnl, "hello, world");
+                vfs_utils::debug_disable_write_crash();
+                r
+            },
+            |e| match e.kind() {
+                ErrorKind::IoError(io) if io.kind() == IoErrorKind::WriteZero => {}
+                unexpected => panic!("expected write zero, got {unexpected:?}"),
+            },
+            |db| assert_eq!(db.data().len(), 0),
+        );
+    }
 }
 
 #[test]
 fn rollback_random_write_failure_log() {
-    emulate_failure_for_rollback(
-        "rollback_random_write_failure_log",
-        |db, jrnl| {
-            // commit a single "good" event
-            db.push(jrnl, "my good key")?;
-            vfs_utils::debug_enable_random_write_crash();
-            let r = db.push(jrnl, "this won't go in");
-            vfs_utils::debug_disable_write_crash();
-            r
-        },
-        |e| match e.kind() {
-            ErrorKind::IoError(io) if io.kind() == IoErrorKind::WriteZero => {}
-            unexpected => panic!("expected write zero, got {unexpected:?}"),
-        },
-        |db| {
-            assert_eq!(db.data().len(), 1);
-            assert_eq!(db.data()[0], "my good key")
-        },
-    )
+    for _ in 0..100 {
+        emulate_failure_for_rollback(
+            "rollback_random_write_failure_log",
+            |db, jrnl| {
+                // commit a single "good" event
+                db.push(jrnl, "my good key")?;
+                vfs_utils::debug_enable_random_write_crash();
+                let r = db.push(jrnl, "this won't go in");
+                vfs_utils::debug_disable_write_crash();
+                r
+            },
+            |e| match e.kind() {
+                ErrorKind::IoError(io) if io.kind() == IoErrorKind::WriteZero => {}
+                unexpected => panic!("expected write zero, got {unexpected:?}"),
+            },
+            |db| {
+                assert_eq!(db.data().len(), 1);
+                assert_eq!(db.data()[0], "my good key")
+            },
+        )
+    }
 }