don't store locks on models

patch-db/Cargo.toml

@@ -11,6 +11,8 @@ repository = "https://github.com/Start9Labs/patch-db"
 version = "0.1.0"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[features]
+debug = ["log"]
 
 [dependencies]
 async-trait = "0.1.42"
@@ -20,7 +22,7 @@ json-patch = { path = "../json-patch" }
 json-ptr = { path = "../json-ptr" }
 lazy_static = "1.4.0"
 log = { version = "*", optional = true }
-nix = "0.20.0"
+nix = "0.22.1"
 patch-db-macro = { path = "../patch-db-macro" }
 serde = { version = "1.0.118", features = ["rc"] }
 serde_cbor = { path = "../cbor" }

patch-db/src/handle.rs

@@ -10,10 +10,13 @@ use tokio::sync::{broadcast::Receiver, RwLock, RwLockReadGuard};
 use crate::{locker::Guard, Locker, PatchDb, Revision, Store, Transaction};
 use crate::{patch::DiffPatch, Error};
 
+#[derive(Debug, Clone, PartialEq, Eq, Default)]
+pub struct HandleId(pub(crate) u64);
+
 #[async_trait]
 pub trait DbHandle: Send + Sync {
     async fn begin<'a>(&'a mut self) -> Result<Transaction<&'a mut Self>, Error>;
-    fn id(&self) -> u64;
+    fn id(&self) -> HandleId;
     fn rebase(&mut self) -> Result<(), Error>;
     fn store(&self) -> Arc<RwLock<Store>>;
     fn subscribe(&self) -> Receiver<Arc<Revision>>;
@@ -75,7 +78,7 @@ impl<Handle: DbHandle + ?Sized> DbHandle for &mut Handle {
             sub,
         })
     }
-    fn id(&self) -> u64 {
+    fn id(&self) -> HandleId {
         (**self).id()
     }
     fn rebase(&mut self) -> Result<(), Error> {
@@ -148,7 +151,7 @@ impl<Handle: DbHandle + ?Sized> DbHandle for &mut Handle {
 }
 
 pub struct PatchDbHandle {
-    pub(crate) id: u64,
+    pub(crate) id: HandleId,
     pub(crate) db: PatchDb,
     pub(crate) locks: Vec<Guard>,
 }
@@ -171,8 +174,8 @@ impl DbHandle for PatchDbHandle {
             updates: DiffPatch::default(),
         })
     }
-    fn id(&self) -> u64 {
-        self.id
+    fn id(&self) -> HandleId {
+        self.id.clone()
     }
     fn rebase(&mut self) -> Result<(), Error> {
         Ok(())
@@ -231,7 +234,7 @@ impl DbHandle for PatchDbHandle {
     }
     async fn lock(&mut self, ptr: JsonPointer, write: bool) {
         self.locks
-            .push(self.db.locker.lock(self.id, ptr, write).await);
+            .push(self.db.locker.lock(self.id.clone(), ptr, write).await);
     }
     async fn get<
         T: for<'de> Deserialize<'de>,

patch-db/src/locker.rs

@@ -1,8 +1,10 @@
-use std::collections::{HashMap, HashSet};
+use std::collections::BTreeMap;
 
 use json_ptr::JsonPointer;
 use tokio::sync::{mpsc, oneshot};
 
+use crate::handle::HandleId;
+
 pub struct Locker {
     sender: mpsc::UnboundedSender<Request>,
 }
@@ -34,7 +36,7 @@ impl Locker {
         });
         Locker { sender }
     }
-    pub async fn lock(&self, handle_id: u64, ptr: JsonPointer, write: bool) -> Guard {
+    pub async fn lock(&self, handle_id: HandleId, ptr: JsonPointer, write: bool) -> Guard {
         let (send, recv) = oneshot::channel();
         self.sender
             .send(Request {
@@ -88,7 +90,7 @@ async fn get_action(
 #[derive(Debug, Default)]
 struct Trie {
     node: Node,
-    children: HashMap<String, Trie>,
+    children: BTreeMap<String, Trie>,
 }
 impl Trie {
     fn child_mut(&mut self, name: &str) -> &mut Self {
@@ -125,31 +127,31 @@ impl Trie {
 
 #[derive(Debug, Default)]
 struct Node {
-    readers: Vec<u64>,
-    writers: Vec<u64>,
+    readers: Vec<HandleId>,
+    writers: Vec<HandleId>,
     reqs: Vec<Request>,
 }
 impl Node {
     // true: If there are any writers, it is `id`.
-    fn write_free(&self, id: u64) -> bool {
-        self.writers.is_empty() || (self.writers.iter().filter(|a| a != &&id).count() == 0)
+    fn write_free(&self, id: &HandleId) -> bool {
+        self.writers.is_empty() || (self.writers.iter().filter(|a| a != &id).count() == 0)
     }
     // true: If there are any readers, it is `id`.
-    fn read_free(&self, id: u64) -> bool {
-        self.readers.is_empty() || (self.readers.iter().filter(|a| a != &&id).count() == 0)
+    fn read_free(&self, id: &HandleId) -> bool {
+        self.readers.is_empty() || (self.readers.iter().filter(|a| a != &id).count() == 0)
     }
     // allow a lock to skip the queue if a lock is already held by the same handle
-    fn can_jump_queue(&self, id: u64) -> bool {
+    fn can_jump_queue(&self, id: &HandleId) -> bool {
         self.writers.contains(&id) || self.readers.contains(&id)
     }
     // `id` is capable of acquiring this node for writing
-    fn write_available(&self, id: u64) -> bool {
+    fn write_available(&self, id: &HandleId) -> bool {
         self.write_free(id)
             && self.read_free(id)
             && (self.reqs.is_empty() || self.can_jump_queue(id))
     }
     // `id` is capable of acquiring this node for reading
-    fn read_available(&self, id: u64) -> bool {
+    fn read_available(&self, id: &HandleId) -> bool {
         self.write_free(id) && (self.reqs.is_empty() || self.can_jump_queue(id))
     }
     fn handle_request(
@@ -157,11 +159,11 @@ impl Node {
         req: Request,
         locks_on_lease: &mut Vec<oneshot::Receiver<LockInfo>>,
     ) -> Option<Request> {
-        if req.lock_info.write() && self.write_available(req.lock_info.handle_id) {
-            self.writers.push(req.lock_info.handle_id);
+        if req.lock_info.write() && self.write_available(&req.lock_info.handle_id) {
+            self.writers.push(req.lock_info.handle_id.clone());
             req.process(locks_on_lease)
-        } else if !req.lock_info.write() && self.read_available(req.lock_info.handle_id) {
-            self.readers.push(req.lock_info.handle_id);
+        } else if !req.lock_info.write() && self.read_available(&req.lock_info.handle_id) {
+            self.readers.push(req.lock_info.handle_id.clone());
             req.process(locks_on_lease)
         } else {
             self.reqs.push(req);
@@ -202,7 +204,7 @@ struct LockInfo {
     ptr: JsonPointer,
     segments_handled: usize,
     write: bool,
-    handle_id: u64,
+    handle_id: HandleId,
 }
 impl LockInfo {
     fn write(&self) -> bool {

patch-db/src/model.rs

@@ -9,7 +9,6 @@ use json_ptr::JsonPointer;
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
-use crate::locker::Guard;
 use crate::{DbHandle, DiffPatch, Error, Revision};
 
 #[derive(Debug)]
@@ -59,7 +58,6 @@ impl<T: Serialize + for<'de> Deserialize<'de>> DerefMut for ModelDataMut<T> {
 pub struct Model<T: Serialize + for<'de> Deserialize<'de>> {
     ptr: JsonPointer,
     phantom: PhantomData<T>,
-    lock: Option<Arc<Guard>>,
 }
 impl<T> Model<T>
 where
@@ -93,7 +91,6 @@ where
         Model {
             ptr,
             phantom: PhantomData,
-            lock: self.lock,
         }
     }
 }
@@ -118,7 +115,6 @@ where
         Self {
             ptr,
             phantom: PhantomData,
-            lock: None,
         }
     }
 }
@@ -146,7 +142,6 @@ where
         Model {
             ptr: self.ptr.clone(),
             phantom: PhantomData,
-            lock: self.lock.clone(),
         }
     }
 }
@@ -297,13 +292,8 @@ where
     T: HasModel + Serialize + for<'de> Deserialize<'de>,
     T::Model: DerefMut<Target = Model<T>>,
 {
-    pub async fn check<Db: DbHandle>(mut self, db: &mut Db) -> Result<Option<T::Model>, Error> {
-        let lock = db
-            .locker()
-            .lock(db.id(), self.0.as_ref().clone(), false)
-            .await;
-        self.0.lock = Some(Arc::new(lock));
-        Ok(if self.exists(db, false).await? {
+    pub async fn check<Db: DbHandle>(self, db: &mut Db) -> Result<Option<T::Model>, Error> {
+        Ok(if self.exists(db, true).await? {
             Some(self.0)
         } else {
             None

patch-db/src/store.rs

@@ -15,6 +15,7 @@ use tokio::fs::File;
 use tokio::sync::broadcast::{Receiver, Sender};
 use tokio::sync::{Mutex, OwnedMutexGuard, RwLock, RwLockWriteGuard};
 
+use crate::handle::HandleId;
 use crate::patch::{diff, DiffPatch, Dump, Revision};
 use crate::Error;
 use crate::{locker::Locker, PatchDbHandle};
@@ -284,9 +285,10 @@ impl PatchDb {
     }
     pub fn handle(&self) -> PatchDbHandle {
         PatchDbHandle {
-            id: self
-                .handle_id
+            id: HandleId(
+                self.handle_id
                     .fetch_add(1, std::sync::atomic::Ordering::SeqCst),
+            ),
             db: self.clone(),
             locks: Vec::new(),
         }

patch-db/src/transaction.rs

@@ -9,6 +9,7 @@ use tokio::sync::broadcast::error::TryRecvError;
 use tokio::sync::broadcast::Receiver;
 use tokio::sync::{RwLock, RwLockReadGuard};
 
+use crate::handle::HandleId;
 use crate::store::Store;
 use crate::Error;
 use crate::{
@@ -21,7 +22,7 @@ use crate::{
 };
 
 pub struct Transaction<Parent: DbHandle> {
-    pub(crate) id: u64,
+    pub(crate) id: HandleId,
     pub(crate) parent: Parent,
     pub(crate) locks: Vec<Guard>,
     pub(crate) updates: DiffPatch,
@@ -79,8 +80,8 @@ impl<Parent: DbHandle + Send + Sync> DbHandle for Transaction<Parent> {
             sub,
         })
     }
-    fn id(&self) -> u64 {
-        self.id
+    fn id(&self) -> HandleId {
+        self.id.clone()
     }
     fn rebase(&mut self) -> Result<(), Error> {
         self.parent.rebase()?;
@@ -167,7 +168,7 @@ impl<Parent: DbHandle + Send + Sync> DbHandle for Transaction<Parent> {
     }
     async fn lock(&mut self, ptr: JsonPointer, write: bool) {
         self.locks
-            .push(self.parent.locker().lock(self.id, ptr, write).await)
+            .push(self.parent.locker().lock(self.id.clone(), ptr, write).await)
     }
     async fn get<
         T: for<'de> Deserialize<'de>,