use std::cell::RefCell;
use std::sync::atomic::{AtomicUsize, Ordering};
-
use std::sync::Mutex as StdMutex;
use std::sync::MutexGuard as StdMutexGuard;
use std::sync::RwLock as StdRwLock;
use std::sync::Condvar as StdCondvar;
#[cfg(feature = "backtrace")]
-use backtrace::Backtrace;
+use {prelude::{HashMap, hash_map}, backtrace::Backtrace, std::sync::Once};
+
+#[cfg(not(feature = "backtrace"))]
+struct Backtrace{}
+#[cfg(not(feature = "backtrace"))]
+impl Backtrace { fn new() -> Backtrace { Backtrace {} } }
pub type LockResult<Guard> = Result<Guard, ()>;
}
static LOCK_IDX: AtomicUsize = AtomicUsize::new(0);
+#[cfg(feature = "backtrace")]
+static mut LOCKS: Option<StdMutex<HashMap<String, Arc<LockMetadata>>>> = None;
+#[cfg(feature = "backtrace")]
+static LOCKS_INIT: Once = Once::new();
+
/// Metadata about a single lock, by id, the set of things locked-before it, and the backtrace of
/// when the Mutex itself was constructed.
struct LockMetadata {
lock_idx: u64,
- locked_before: StdMutex<HashSet<Arc<LockMetadata>>>,
- #[cfg(feature = "backtrace")]
- lock_construction_bt: Backtrace,
+ locked_before: StdMutex<HashSet<LockDep>>,
+ _lock_construction_bt: Backtrace,
}
impl PartialEq for LockMetadata {
fn eq(&self, o: &LockMetadata) -> bool { self.lock_idx == o.lock_idx }
fn hash<H: std::hash::Hasher>(&self, hasher: &mut H) { hasher.write_u64(self.lock_idx); }
}
+struct LockDep {
+ lock: Arc<LockMetadata>,
+ lockdep_trace: Option<Backtrace>,
+}
+impl LockDep {
+ /// Note that `Backtrace::new()` is rather expensive so we rely on the caller to fill in the
+ /// `lockdep_backtrace` field after ensuring we need it.
+ fn new_without_bt(lock: &Arc<LockMetadata>) -> Self {
+ Self { lock: Arc::clone(lock), lockdep_trace: None }
+ }
+}
+impl PartialEq for LockDep {
+ fn eq(&self, o: &LockDep) -> bool { self.lock.lock_idx == o.lock.lock_idx }
+}
+impl Eq for LockDep {}
+impl std::hash::Hash for LockDep {
+ fn hash<H: std::hash::Hasher>(&self, hasher: &mut H) { hasher.write_u64(self.lock.lock_idx); }
+}
+
+#[cfg(feature = "backtrace")]
+fn get_construction_location(backtrace: &Backtrace) -> String {
+ // Find the first frame that is after `debug_sync` (or that is in our tests) and use
+ // that as the mutex construction site. Note that the first few frames may be in
+ // the `backtrace` crate, so we have to ignore those.
+ let sync_mutex_constr_regex = regex::Regex::new(r"lightning.*debug_sync.*new").unwrap();
+ let mut found_debug_sync = false;
+ for frame in backtrace.frames() {
+ for symbol in frame.symbols() {
+ let symbol_name = symbol.name().unwrap().as_str().unwrap();
+ if !sync_mutex_constr_regex.is_match(symbol_name) {
+ if found_debug_sync {
+ if let Some(col) = symbol.colno() {
+ return format!("{}:{}:{}", symbol.filename().unwrap().display(), symbol.lineno().unwrap(), col);
+ } else {
+ // Windows debug symbols don't support column numbers, so fall back to
+ // line numbers only if no `colno` is available
+ return format!("{}:{}", symbol.filename().unwrap().display(), symbol.lineno().unwrap());
+ }
+ }
+ } else { found_debug_sync = true; }
+ }
+ }
+ panic!("Couldn't find mutex construction callsite");
+}
+
impl LockMetadata {
- fn new() -> LockMetadata {
- LockMetadata {
+ fn new() -> Arc<LockMetadata> {
+ let backtrace = Backtrace::new();
+ let lock_idx = LOCK_IDX.fetch_add(1, Ordering::Relaxed) as u64;
+
+ let res = Arc::new(LockMetadata {
locked_before: StdMutex::new(HashSet::new()),
- lock_idx: LOCK_IDX.fetch_add(1, Ordering::Relaxed) as u64,
- #[cfg(feature = "backtrace")]
- lock_construction_bt: Backtrace::new(),
+ lock_idx,
+ _lock_construction_bt: backtrace,
+ });
+
+ #[cfg(feature = "backtrace")]
+ {
+ let lock_constr_location = get_construction_location(&res._lock_construction_bt);
+ LOCKS_INIT.call_once(|| { unsafe { LOCKS = Some(StdMutex::new(HashMap::new())); } });
+ let mut locks = unsafe { LOCKS.as_ref() }.unwrap().lock().unwrap();
+ match locks.entry(lock_constr_location) {
+ hash_map::Entry::Occupied(e) => return Arc::clone(e.get()),
+ hash_map::Entry::Vacant(e) => { e.insert(Arc::clone(&res)); },
+ }
}
+ res
}
// Returns whether we were a recursive lock (only relevant for read)
}
for locked in held.borrow().iter() {
if !read && *locked == *this {
- panic!("Tried to lock a lock while it was held!");
+ // With `feature = "backtrace"` set, we may be looking at different instances
+ // of the same lock.
+ debug_assert!(cfg!(feature = "backtrace"), "Tried to acquire a lock while it was held!");
}
for locked_dep in locked.locked_before.lock().unwrap().iter() {
- if *locked_dep == *this {
+ if locked_dep.lock == *this && locked_dep.lock != *locked {
#[cfg(feature = "backtrace")]
- panic!("Tried to violate existing lockorder.\nMutex that should be locked after the current lock was created at the following backtrace.\nNote that to get a backtrace for the lockorder violation, you should set RUST_BACKTRACE=1\n{:?}", locked.lock_construction_bt);
+ panic!("Tried to violate existing lockorder.\nMutex that should be locked after the current lock was created at the following backtrace.\nNote that to get a backtrace for the lockorder violation, you should set RUST_BACKTRACE=1\nLock being taken constructed at: {} ({}):\n{:?}\nLock constructed at: {} ({})\n{:?}\n\nLock dep created at:\n{:?}\n\n",
+ get_construction_location(&this._lock_construction_bt), this.lock_idx, this._lock_construction_bt,
+ get_construction_location(&locked._lock_construction_bt), locked.lock_idx, locked._lock_construction_bt,
+ locked_dep.lockdep_trace);
#[cfg(not(feature = "backtrace"))]
panic!("Tried to violate existing lockorder. Build with the backtrace feature for more info.");
}
}
// Insert any already-held locks in our locked-before set.
- this.locked_before.lock().unwrap().insert(Arc::clone(locked));
+ let mut locked_before = this.locked_before.lock().unwrap();
+ let mut lockdep = LockDep::new_without_bt(locked);
+ if !locked_before.contains(&lockdep) {
+ lockdep.lockdep_trace = Some(Backtrace::new());
+ locked_before.insert(lockdep);
+ }
}
held.borrow_mut().insert(Arc::clone(this));
inserted = true;
// Since a try-lock will simply fail if the lock is held already, we do not
// consider try-locks to ever generate lockorder inversions. However, if a try-lock
// succeeds, we do consider it to have created lockorder dependencies.
+ let mut locked_before = this.locked_before.lock().unwrap();
for locked in held.borrow().iter() {
- this.locked_before.lock().unwrap().insert(Arc::clone(locked));
+ let mut lockdep = LockDep::new_without_bt(locked);
+ if !locked_before.contains(&lockdep) {
+ lockdep.lockdep_trace = Some(Backtrace::new());
+ locked_before.insert(lockdep);
+ }
}
held.borrow_mut().insert(Arc::clone(this));
});
impl<T> Mutex<T> {
pub fn new(inner: T) -> Mutex<T> {
- Mutex { inner: StdMutex::new(inner), deps: Arc::new(LockMetadata::new()) }
+ Mutex { inner: StdMutex::new(inner), deps: LockMetadata::new() }
}
pub fn lock<'a>(&'a self) -> LockResult<MutexGuard<'a, T>> {
impl<T> RwLock<T> {
pub fn new(inner: T) -> RwLock<T> {
- RwLock { inner: StdRwLock::new(inner), deps: Arc::new(LockMetadata::new()) }
+ RwLock { inner: StdRwLock::new(inner), deps: LockMetadata::new() }
}
pub fn read<'a>(&'a self) -> LockResult<RwLockReadGuard<'a, T>> {
}
}
-#[test]
-#[should_panic]
-fn recursive_lock_fail() {
- let mutex = Mutex::new(());
- let _a = mutex.lock().unwrap();
- let _b = mutex.lock().unwrap();
-}
-
-#[test]
-fn recursive_read() {
- let lock = RwLock::new(());
- let _a = lock.read().unwrap();
- let _b = lock.read().unwrap();
-}
+pub type FairRwLock<T> = RwLock<T>;
-#[test]
-#[should_panic]
-fn lockorder_fail() {
- let a = Mutex::new(());
- let b = Mutex::new(());
- {
- let _a = a.lock().unwrap();
- let _b = b.lock().unwrap();
- }
- {
- let _b = b.lock().unwrap();
- let _a = a.lock().unwrap();
+mod tests {
+ use super::{RwLock, Mutex};
+
+ #[test]
+ #[should_panic]
+ #[cfg(not(feature = "backtrace"))]
+ fn recursive_lock_fail() {
+ let mutex = Mutex::new(());
+ let _a = mutex.lock().unwrap();
+ let _b = mutex.lock().unwrap();
+ }
+
+ #[test]
+ fn recursive_read() {
+ let lock = RwLock::new(());
+ let _a = lock.read().unwrap();
+ let _b = lock.read().unwrap();
+ }
+
+ #[test]
+ #[should_panic]
+ fn lockorder_fail() {
+ let a = Mutex::new(());
+ let b = Mutex::new(());
+ {
+ let _a = a.lock().unwrap();
+ let _b = b.lock().unwrap();
+ }
+ {
+ let _b = b.lock().unwrap();
+ let _a = a.lock().unwrap();
+ }
}
-}
-#[test]
-#[should_panic]
-fn write_lockorder_fail() {
- let a = RwLock::new(());
- let b = RwLock::new(());
- {
- let _a = a.write().unwrap();
- let _b = b.write().unwrap();
- }
- {
- let _b = b.write().unwrap();
- let _a = a.write().unwrap();
+ #[test]
+ #[should_panic]
+ fn write_lockorder_fail() {
+ let a = RwLock::new(());
+ let b = RwLock::new(());
+ {
+ let _a = a.write().unwrap();
+ let _b = b.write().unwrap();
+ }
+ {
+ let _b = b.write().unwrap();
+ let _a = a.write().unwrap();
+ }
}
-}
-#[test]
-#[should_panic]
-fn read_lockorder_fail() {
- let a = RwLock::new(());
- let b = RwLock::new(());
- {
- let _a = a.read().unwrap();
- let _b = b.read().unwrap();
- }
- {
- let _b = b.read().unwrap();
- let _a = a.read().unwrap();
+ #[test]
+ #[should_panic]
+ fn read_lockorder_fail() {
+ let a = RwLock::new(());
+ let b = RwLock::new(());
+ {
+ let _a = a.read().unwrap();
+ let _b = b.read().unwrap();
+ }
+ {
+ let _b = b.read().unwrap();
+ let _a = a.read().unwrap();
+ }
}
-}
-#[test]
-fn read_recurisve_no_lockorder() {
- // Like the above, but note that no lockorder is implied when we recursively read-lock a
- // RwLock, causing this to pass just fine.
- let a = RwLock::new(());
- let b = RwLock::new(());
- let _outer = a.read().unwrap();
- {
- let _a = a.read().unwrap();
- let _b = b.read().unwrap();
- }
- {
- let _b = b.read().unwrap();
- let _a = a.read().unwrap();
+ #[test]
+ fn read_recursive_no_lockorder() {
+ // Like the above, but note that no lockorder is implied when we recursively read-lock a
+ // RwLock, causing this to pass just fine.
+ let a = RwLock::new(());
+ let b = RwLock::new(());
+ let _outer = a.read().unwrap();
+ {
+ let _a = a.read().unwrap();
+ let _b = b.read().unwrap();
+ }
+ {
+ let _b = b.read().unwrap();
+ let _a = a.read().unwrap();
+ }
}
-}
-#[test]
-#[should_panic]
-fn read_write_lockorder_fail() {
- let a = RwLock::new(());
- let b = RwLock::new(());
- {
- let _a = a.write().unwrap();
- let _b = b.read().unwrap();
- }
- {
- let _b = b.read().unwrap();
- let _a = a.write().unwrap();
+ #[test]
+ #[should_panic]
+ fn read_write_lockorder_fail() {
+ let a = RwLock::new(());
+ let b = RwLock::new(());
+ {
+ let _a = a.write().unwrap();
+ let _b = b.read().unwrap();
+ }
+ {
+ let _b = b.read().unwrap();
+ let _a = a.write().unwrap();
+ }
}
}
-
-pub type FairRwLock<T> = RwLock<T>;
projects / rust-lightning / commitdiff