f provide more debug information in panics

Author: TheBlueMatt

lightning/src/debug_sync.rs

@@ -94,6 +94,26 @@ 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_symbol<'a>(backtrace: &'a Backtrace) -> (&'a str, u64) {
+	// Find the first frame which is after `debug_sync` (or which is in our tests) and use
+	// that as the mutex construction site. Note that the first few frames may be in
+	// `backtrace`, 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 {
+					return (symbol_name, symbol.addr().unwrap() as usize as u64);
+				}
+			} else { found_debug_sync = true; }
+		}
+	}
+	panic!("Couldn't find mutex construction callsite");
+}
+
 impl LockMetadata {
 	fn new() -> Arc<LockMetadata> {
 		let lock_idx;
@@ -104,24 +124,7 @@ impl LockMetadata {
 
 		#[cfg(feature = "backtrace")]
 		{
-			let mut symbol_ptr = None;
-			// Find the first frame which is after `debug_sync` (or which is in our tests) and use
-			// that as the mutex construction site. Note that the first few frames may be in
-			// `backtrace`, 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;
-			'trace_walk: 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 {
-							symbol_ptr = Some(symbol.addr().unwrap() as usize as u64);
-							break 'trace_walk;
-						}
-					} else { found_debug_sync = true; }
-				}
-			}
-			lock_idx = symbol_ptr.unwrap();
+			lock_idx = get_construction_symbol(&backtrace).1;
 			LOCKS_INIT.call_once(|| { unsafe { LOCKS = Some(StdMutex::new(HashMap::new())); } });
 			if let Some(metadata) = unsafe { LOCKS.as_ref() }.unwrap().lock().unwrap().get(&lock_idx) {
 				return Arc::clone(&metadata);
@@ -167,7 +170,10 @@ impl LockMetadata {
 				for locked_dep in locked.locked_before.lock().unwrap().iter() {
 					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\nLock constructed at:\n{:?}\n\nLock dep created at:\n{:?}\n\n", locked._lock_construction_bt, locked_dep.lockdep_trace);
+						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_symbol(&this._lock_construction_bt).0, this._lock_construction_bt,
+							get_construction_symbol(&locked._lock_construction_bt).0, 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.");
 					}