Replace dashmap with scc

Also add a _lot_ of debug

serial_test/Cargo.toml

@@ -20,7 +20,8 @@ log = { version = "0.4", optional = true }
 futures = { version = "^0.3", default_features = false, features = [
     "executor",
 ], optional = true}
-dashmap = { version = "5"}
+scc = { version = "2"}
+env_logger = {version="0.10", optional=true}
 
 [dev-dependencies]
 itertools = "0.10"
@@ -32,6 +33,9 @@ default = ["logging", "async"]
 ## Switches on debug logging (and requires the `log` package)
 logging = ["log"]
 
+## Switches on debug with env_logger. Generally only needed by internal serial_test work.
+test_logging = ["logging", "env_logger", "serial_test_derive/test_logging"]
+
 ## Enables async features (and requires the `futures` package)
 async = ["futures", "serial_test_derive/async"]
 
@@ -48,4 +52,4 @@ rustdoc-args = ["--cfg", "docsrs"]
 
 [package.metadata.cargo-all-features]
 skip_optional_dependencies = true
-denylist = ["docsrs"]
+denylist = ["docsrs", "test_logging"]

serial_test/src/code_lock.rs

@@ -1,11 +1,7 @@
 use crate::rwlock::{Locks, MutexGuardWrapper};
-use dashmap::{try_result::TryResult, DashMap};
-#[cfg(feature = "logging")]
-use log::debug;
 use once_cell::sync::OnceCell;
+use scc::{hash_map::Entry, HashMap};
 use std::sync::atomic::AtomicU32;
-#[cfg(feature = "logging")]
-use std::time::Instant;
 
 #[derive(Clone)]
 pub(crate) struct UniqueReentrantMutex {
@@ -41,51 +37,34 @@ impl UniqueReentrantMutex {
 }
 
 #[inline]
-pub(crate) fn global_locks() -> &'static DashMap<String, UniqueReentrantMutex> {
-    static LOCKS: OnceCell<DashMap<String, UniqueReentrantMutex>> = OnceCell::new();
-    LOCKS.get_or_init(DashMap::new)
+pub(crate) fn global_locks() -> &'static HashMap<String, UniqueReentrantMutex> {
+    #[cfg(feature = "test_logging")]
+    let _ = env_logger::builder().try_init();
+    static LOCKS: OnceCell<HashMap<String, UniqueReentrantMutex>> = OnceCell::new();
+    LOCKS.get_or_init(HashMap::new)
 }
 
 static MUTEX_ID: AtomicU32 = AtomicU32::new(1);
 
-impl Default for UniqueReentrantMutex {
-    fn default() -> Self {
+impl UniqueReentrantMutex {
+    fn new_mutex(name: &str) -> Self {
         Self {
-            locks: Locks::new(),
+            locks: Locks::new(name),
             id: MUTEX_ID.fetch_add(1, std::sync::atomic::Ordering::SeqCst),
         }
     }
 }
 
 pub(crate) fn check_new_key(name: &str) {
-    #[cfg(feature = "logging")]
-    let start = Instant::now();
-    loop {
-        #[cfg(feature = "logging")]
-        {
-            let duration = start.elapsed();
-            debug!("Waiting for '{}' {:?}", name, duration);
-        }
-        // Check if a new key is needed. Just need a read lock, which can be done in sync with everyone else
-        match global_locks().try_get(name) {
-            TryResult::Present(_) => {
-                return;
-            }
-            TryResult::Locked => {
-                continue; // wasn't able to get read lock
-            }
-            TryResult::Absent => {} // do the write path below
-        };
-
-        // This is the rare path, which avoids the multi-writer situation mostly
-        let try_entry = global_locks().try_entry(name.to_string());
+    // Check if a new key is needed. Just need a read lock, which can be done in sync with everyone else
+    if global_locks().contains(name) {
+        return;
+    };
 
-        if let Some(entry) = try_entry {
-            entry.or_default();
-            return;
-        }
-
-        // If the try_entry fails, then go around the loop again
-        // Odds are another test was also locking on the write and has now written the key
-    }
+    // This is the rare path, which avoids the multi-writer situation mostly
+    let entry = global_locks().entry(name.to_owned());
+    match entry {
+        Entry::Occupied(o) => o,
+        Entry::Vacant(v) => v.insert_entry(UniqueReentrantMutex::new_mutex(name)),
+    };
 }

serial_test/src/parallel_code_lock.rs

@@ -7,12 +7,12 @@ use std::panic;
 
 fn get_locks(
     names: Vec<&str>,
-) -> Vec<dashmap::mapref::one::Ref<'_, String, crate::code_lock::UniqueReentrantMutex>> {
+) -> Vec<crate::code_lock::UniqueReentrantMutex> {
     names
         .into_iter()
         .map(|name| {
             check_new_key(name);
-            global_locks().get(name).expect("key to be set")
+            global_locks().get(name).expect("key to be set").get().clone()
         })
         .collect::<Vec<_>>()
 }
@@ -103,6 +103,7 @@ mod tests {
             global_locks()
                 .get("unlock_on_assert_sync_without_return")
                 .unwrap()
+                .get()
                 .parallel_count(),
             0
         );
@@ -124,6 +125,7 @@ mod tests {
             global_locks()
                 .get("unlock_on_assert_sync_with_return")
                 .unwrap()
+                .get()
                 .parallel_count(),
             0
         );
@@ -153,6 +155,7 @@ mod tests {
             global_locks()
                 .get("unlock_on_assert_async_without_return")
                 .unwrap()
+                .get()
                 .parallel_count(),
             0
         );
@@ -186,6 +189,7 @@ mod tests {
             global_locks()
                 .get("unlock_on_assert_async_with_return")
                 .unwrap()
+                .get()
                 .parallel_count(),
             0
         );

serial_test/src/rwlock.rs

@@ -1,5 +1,7 @@
 use parking_lot::{Condvar, Mutex, ReentrantMutex, ReentrantMutexGuard};
 use std::{sync::Arc, time::Duration};
+#[cfg(feature = "logging")]
+use log::debug;
 
 struct LockState {
     parallels: u32,
@@ -14,6 +16,9 @@ struct LockData {
 #[derive(Clone)]
 pub(crate) struct Locks {
     arc: Arc<LockData>,
+    // Name we're locking for (mostly test usage)
+    #[cfg(feature = "logging")]
+    pub(crate) name: String
 }
 
 pub(crate) struct MutexGuardWrapper<'a> {
@@ -24,18 +29,22 @@ pub(crate) struct MutexGuardWrapper<'a> {
 
 impl<'a> Drop for MutexGuardWrapper<'a> {
     fn drop(&mut self) {
+        #[cfg(feature = "logging")]
+        debug!("End serial");
         self.locks.arc.condvar.notify_one();
     }
 }
 
 impl Locks {
-    pub fn new() -> Locks {
+    pub fn new(name: &str) -> Locks {
         Locks {
             arc: Arc::new(LockData {
                 mutex: Mutex::new(LockState { parallels: 0 }),
                 condvar: Condvar::new(),
                 serial: Default::default(),
             }),
+            #[cfg(feature = "logging")]
+            name: name.to_owned()
         }
     }
 
@@ -45,16 +54,25 @@ impl Locks {
     }
 
     pub fn serial(&self) -> MutexGuardWrapper {
+        #[cfg(feature = "logging")]
+        debug!("Get serial lock '{}'", self.name);        
         let mut lock_state = self.arc.mutex.lock();
         loop {
+            #[cfg(feature = "logging")]
+            debug!("Serial acquire {} {}", lock_state.parallels, self.name);
             // If all the things we want are true, try to lock out serial
             if lock_state.parallels == 0 {
                 let possible_serial_lock = self.arc.serial.try_lock();
                 if let Some(serial_lock) = possible_serial_lock {
+                    #[cfg(feature = "logging")]
+                    debug!("Got serial '{}'", self.name);                    
                     return MutexGuardWrapper {
                         mutex_guard: serial_lock,
                         locks: self.clone(),
                     };
+                } else {
+                    #[cfg(feature = "logging")]
+                    debug!("Someone else has serial '{}'", self.name);                    
                 }
             }
 
@@ -65,8 +83,12 @@ impl Locks {
     }
 
     pub fn start_parallel(&self) {
+        #[cfg(feature = "logging")]
+        debug!("Get parallel lock '{}'", self.name);
         let mut lock_state = self.arc.mutex.lock();
         loop {
+            #[cfg(feature = "logging")]
+            debug!("Parallel, existing {} '{}'", lock_state.parallels, self.name);            
             if lock_state.parallels > 0 {
                 // fast path, as someone else already has it locked
                 lock_state.parallels += 1;
@@ -75,18 +97,24 @@ impl Locks {
 
             let possible_serial_lock = self.arc.serial.try_lock();
             if possible_serial_lock.is_some() {
+                #[cfg(feature = "logging")]
+                debug!("Parallel first '{}'", self.name);                
                 // We now know no-one else has the serial lock, so we can add to parallel
                 lock_state.parallels = 1; // Had to have been 0 before, as otherwise we'd have hit the fast path
                 return;
             }
 
+            #[cfg(feature = "logging")]
+            debug!("Parallel waiting '{}'", self.name);
             self.arc
                 .condvar
                 .wait_for(&mut lock_state, Duration::from_secs(1));
         }
     }
 
     pub fn end_parallel(&self) {
+        #[cfg(feature = "logging")]
+        debug!("End parallel");        
         let mut lock_state = self.arc.mutex.lock();
         assert!(lock_state.parallels > 0);
         lock_state.parallels -= 1;

serial_test/src/serial_code_lock.rs

@@ -9,7 +9,7 @@ macro_rules! core_internal {
             .into_iter()
             .map(|name| {
                 check_new_key(name);
-                global_locks().get(name).expect("key to be set")
+                global_locks().get(name).expect("key to be set").get().clone()
             })
             .collect();
         let _guards: Vec<_> = unlocks.iter().map(|unlock| unlock.lock()).collect();
@@ -84,7 +84,7 @@ mod tests {
                 check_new_key("foo");
                 {
                     let unlock = local_locks.get("foo").expect("read didn't work");
-                    let mutex = unlock.value();
+                    let mutex = unlock.get();
 
                     let mut ptr_guard = local_ptrs
                         .try_write_for(Duration::from_secs(1))
@@ -113,6 +113,6 @@ mod tests {
                 assert!(false);
             })
         });
-        assert!(!global_locks().get("assert").unwrap().is_locked());
+        assert!(!global_locks().get("assert").unwrap().get().is_locked());
     }
 }

serial_test_derive/Cargo.toml

@@ -22,4 +22,6 @@ env_logger = "0.10"
 prettyplease = "0.2"
 
 [features]
-async = []
+default = []
+async = []
+test_logging = []