lock api now returns errors

patch-db/src/handle.rs

@@ -1,16 +1,16 @@
+use std::collections::BTreeSet;
 use std::sync::Arc;
 
 use async_trait::async_trait;
 use json_ptr::{JsonPointer, SegList};
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
-use std::collections::BTreeSet;
+use tokio::sync::broadcast::Receiver;
-use tokio::sync::RwLockWriteGuard;
+use tokio::sync::{RwLock, RwLockReadGuard, RwLockWriteGuard};
-use tokio::sync::{broadcast::Receiver, RwLock, RwLockReadGuard};
 
-use crate::locker::LockType;
+use crate::locker::{Guard, LockError, LockType};
-use crate::{locker::Guard, Locker, PatchDb, Revision, Store, Transaction};
+use crate::patch::DiffPatch;
-use crate::{patch::DiffPatch, Error};
+use crate::{Error, Locker, PatchDb, Revision, Store, Transaction};
 
 #[derive(Debug, Clone, Default)]
 pub struct HandleId {
@@ -68,7 +68,7 @@ pub trait DbHandle: Send + Sync {
         patch: DiffPatch,
         store_write_lock: Option<RwLockWriteGuard<'_, Store>>,
     ) -> Result<Option<Arc<Revision>>, Error>;
-    async fn lock(&mut self, ptr: JsonPointer, lock_type: LockType) -> ();
+    async fn lock(&mut self, ptr: JsonPointer, lock_type: LockType) -> Result<(), LockError>;
     async fn get<
         T: for<'de> Deserialize<'de>,
         S: AsRef<str> + Send + Sync,
@@ -154,7 +154,7 @@ impl<Handle: DbHandle + ?Sized> DbHandle for &mut Handle {
     ) -> Result<Option<Arc<Revision>>, Error> {
         (*self).apply(patch, store_write_lock).await
     }
-    async fn lock(&mut self, ptr: JsonPointer, lock_type: LockType) {
+    async fn lock(&mut self, ptr: JsonPointer, lock_type: LockType) -> Result<(), LockError> {
         (*self).lock(ptr, lock_type).await
     }
     async fn get<
@@ -266,9 +266,10 @@ impl DbHandle for PatchDbHandle {
     ) -> Result<Option<Arc<Revision>>, Error> {
         self.db.apply(patch, None, store_write_lock).await
     }
-    async fn lock(&mut self, ptr: JsonPointer, lock_type: LockType) {
+    async fn lock(&mut self, ptr: JsonPointer, lock_type: LockType) -> Result<(), LockError> {
-        self.locks
+        Ok(self
-            .push(self.db.locker.lock(self.id.clone(), ptr, lock_type).await);
+            .locks
+            .push(self.db.locker.lock(self.id.clone(), ptr, lock_type).await?))
     }
     async fn get<
         T: for<'de> Deserialize<'de>,

patch-db/src/lib.rs

@@ -2,6 +2,7 @@ use std::io::Error as IOError;
 use std::sync::Arc;
 
 use json_ptr::JsonPointer;
+use locker::LockError;
 use thiserror::Error;
 use tokio::sync::broadcast::error::TryRecvError;
 
@@ -20,8 +21,6 @@ mod proptest;
 mod test;
 
 pub use handle::{DbHandle, PatchDbHandle};
-pub use json_patch;
-pub use json_ptr;
 pub use locker::{LockType, Locker};
 pub use model::{
     BoxModel, HasModel, Map, MapModel, Model, ModelData, ModelDataMut, OptionModel, VecModel,
@@ -30,6 +29,7 @@ pub use patch::{DiffPatch, Dump, Revision};
 pub use patch_db_macro::HasModel;
 pub use store::{PatchDb, Store};
 pub use transaction::Transaction;
+pub use {json_patch, json_ptr};
 
 #[derive(Error, Debug)]
 pub enum Error {
@@ -53,4 +53,6 @@ pub enum Error {
     Subscriber(#[from] TryRecvError),
     #[error("Node Does Not Exist: {0}")]
     NodeDoesNotExist(JsonPointer),
+    #[error("Invalid Lock Request: {0}")]
+    LockError(#[from] LockError),
 }

patch-db/src/locker.rs

@@ -209,7 +209,12 @@ impl Locker {
         });
         Locker { sender }
     }
-    pub async fn lock(&self, handle_id: HandleId, ptr: JsonPointer, lock_type: LockType) -> Guard {
+    pub async fn lock(
+        &self,
+        handle_id: HandleId,
+        ptr: JsonPointer,
+        lock_type: LockType,
+    ) -> Result<Guard, LockError> {
         struct CancelGuard {
             lock_info: Option<LockInfo>,
             channel: Option<oneshot::Sender<LockInfo>>,
@@ -246,7 +251,7 @@ impl Locker {
             .unwrap();
         let res = (&mut cancel_guard.recv).await.unwrap();
         cancel_guard.channel.take();
-        res
+        Ok(res)
     }
 }
 
@@ -910,6 +915,31 @@ impl std::fmt::Display for LockType {
     }
 }
 
+#[derive(Debug, Clone, thiserror::Error)]
+pub enum LockError {
+    #[error("Lock Taxonomy Escalation: Session = {session:?}, First = {first}, Second = {second}")]
+    LockTaxonomyEscalation {
+        session: HandleId,
+        first: JsonPointer,
+        second: JsonPointer,
+    },
+    #[error("Lock Type Escalation: Session = {session:?}, Pointer = {ptr}, First = {first}, Second = {second}")]
+    LockTypeEscalation {
+        session: HandleId,
+        ptr: JsonPointer,
+        first: LockType,
+        second: LockType,
+    },
+    #[error(
+        "Non-Canonical Lock Ordering: Session = {session:?}, First = {first}, Second = {second}"
+    )]
+    NonCanonicalOrdering {
+        session: HandleId,
+        first: JsonPointer,
+        second: JsonPointer,
+    },
+}
+
 #[derive(Debug)]
 struct Request {
     lock_info: LockInfo,

patch-db/src/model.rs

@@ -9,7 +9,7 @@ use json_ptr::JsonPointer;
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
-use crate::locker::LockType;
+use crate::locker::{LockError, LockType};
 use crate::{DbHandle, DiffPatch, Error, Revision};
 
 #[derive(Debug)]
@@ -65,19 +65,23 @@ impl<T> Model<T>
 where
     T: Serialize + for<'de> Deserialize<'de>,
 {
-    pub async fn lock<Db: DbHandle>(&self, db: &mut Db, lock_type: LockType) {
+    pub async fn lock<Db: DbHandle>(
+        &self,
+        db: &mut Db,
+        lock_type: LockType,
+    ) -> Result<(), LockError> {
         db.lock(self.ptr.clone(), lock_type).await
     }
 
     pub async fn get<Db: DbHandle>(&self, db: &mut Db, lock: bool) -> Result<ModelData<T>, Error> {
         if lock {
-            self.lock(db, LockType::Read).await;
+            self.lock(db, LockType::Read).await?;
         }
         Ok(ModelData(db.get(&self.ptr).await?))
     }
 
     pub async fn get_mut<Db: DbHandle>(&self, db: &mut Db) -> Result<ModelDataMut<T>, Error> {
-        self.lock(db, LockType::Write).await;
+        self.lock(db, LockType::Write).await?;
         let original = db.get_value(&self.ptr, None).await?;
         let current = serde_json::from_value(original.clone())?;
         Ok(ModelDataMut {
@@ -105,7 +109,7 @@ where
         db: &mut Db,
         value: &T,
     ) -> Result<Option<Arc<Revision>>, Error> {
-        self.lock(db, LockType::Write).await;
+        self.lock(db, LockType::Write).await?;
         db.put(&self.ptr, value).await
     }
 }
@@ -228,7 +232,11 @@ impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> HasModel for Box<T> {
 #[derive(Debug)]
 pub struct OptionModel<T: HasModel + Serialize + for<'de> Deserialize<'de>>(T::Model);
 impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> OptionModel<T> {
-    pub async fn lock<Db: DbHandle>(&self, db: &mut Db, lock_type: LockType) {
+    pub async fn lock<Db: DbHandle>(
+        &self,
+        db: &mut Db,
+        lock_type: LockType,
+    ) -> Result<(), LockError> {
         db.lock(self.0.as_ref().clone(), lock_type).await
     }
 
@@ -238,7 +246,7 @@ impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> OptionModel<T> {
         lock: bool,
     ) -> Result<ModelData<Option<T>>, Error> {
         if lock {
-            self.lock(db, LockType::Read).await;
+            self.lock(db, LockType::Read).await?;
         }
         Ok(ModelData(db.get(self.0.as_ref()).await?))
     }
@@ -247,7 +255,7 @@ impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> OptionModel<T> {
         &self,
         db: &mut Db,
     ) -> Result<ModelDataMut<Option<T>>, Error> {
-        self.lock(db, LockType::Write).await;
+        self.lock(db, LockType::Write).await?;
         let original = db.get_value(self.0.as_ref(), None).await?;
         let current = serde_json::from_value(original.clone())?;
         Ok(ModelDataMut {
@@ -259,7 +267,7 @@ impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> OptionModel<T> {
 
     pub async fn exists<Db: DbHandle>(&self, db: &mut Db, lock: bool) -> Result<bool, Error> {
         if lock {
-            db.lock(self.0.as_ref().clone(), LockType::Exist).await;
+            db.lock(self.0.as_ref().clone(), LockType::Exist).await?;
         }
         Ok(db.exists(&self.as_ref(), None).await?)
     }
@@ -285,7 +293,7 @@ impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> OptionModel<T> {
     }
 
     pub async fn delete<Db: DbHandle>(&self, db: &mut Db) -> Result<Option<Arc<Revision>>, Error> {
-        db.lock(self.as_ref().clone(), LockType::Write).await;
+        db.lock(self.as_ref().clone(), LockType::Write).await?;
         db.put(self.as_ref(), &Value::Null).await
     }
 }
@@ -319,7 +327,7 @@ where
         db: &mut Db,
         value: &T,
     ) -> Result<Option<Arc<Revision>>, Error> {
-        db.lock(self.as_ref().clone(), LockType::Write).await;
+        db.lock(self.as_ref().clone(), LockType::Write).await?;
         db.put(self.as_ref(), value).await
     }
 }
@@ -490,7 +498,7 @@ where
         lock: bool,
     ) -> Result<BTreeSet<T::Key>, Error> {
         if lock {
-            db.lock(self.as_ref().clone(), LockType::Exist).await;
+            db.lock(self.as_ref().clone(), LockType::Exist).await?;
         }
         let set = db.keys(self.as_ref(), None).await?;
         Ok(set
@@ -499,7 +507,7 @@ where
             .collect::<Result<_, _>>()?)
     }
     pub async fn remove<Db: DbHandle>(&self, db: &mut Db, key: &T::Key) -> Result<(), Error> {
-        db.lock(self.as_ref().clone(), LockType::Write).await;
+        db.lock(self.as_ref().clone(), LockType::Write).await?;
         if db.exists(self.clone().idx(key).as_ref(), None).await? {
             db.apply(
                 DiffPatch(Patch(vec![PatchOperation::Remove(RemoveOperation {

patch-db/src/transaction.rs

@@ -10,7 +10,7 @@ use tokio::sync::broadcast::Receiver;
 use tokio::sync::{RwLock, RwLockReadGuard, RwLockWriteGuard};
 
 use crate::handle::HandleId;
-use crate::locker::{Guard, LockType, Locker};
+use crate::locker::{Guard, LockError, LockType, Locker};
 use crate::patch::{DiffPatch, Revision};
 use crate::store::Store;
 use crate::{DbHandle, Error, PatchDbHandle};
@@ -165,13 +165,13 @@ impl<Parent: DbHandle + Send + Sync> DbHandle for Transaction<Parent> {
         self.updates.append(patch);
         Ok(None)
     }
-    async fn lock(&mut self, ptr: JsonPointer, lock_type: LockType) {
+    async fn lock(&mut self, ptr: JsonPointer, lock_type: LockType) -> Result<(), LockError> {
-        self.locks.push(
+        Ok(self.locks.push(
             self.parent
                 .locker()
                 .lock(self.id.clone(), ptr, lock_type)
-                .await,
+                .await?,
-        )
+        ))
     }
     async fn get<
         T: for<'de> Deserialize<'de>,