Feat movable tree

crates/loro-common/src/error.rs

@@ -1,6 +1,6 @@
 use thiserror::Error;
 
-use crate::{PeerID, ID};
+use crate::{PeerID, TreeID, ID};
 
 pub type LoroResult<T> = Result<T, LoroError>;
 
@@ -32,6 +32,8 @@ pub enum LoroError {
     OutOfBound { pos: usize, len: usize },
     #[error("Every op id should be unique. ID {id} has been used. You should use a new PeerID to edit the content. ")]
     UsedOpID { id: ID },
+    #[error("Movable Tree Error")]
+    TreeError(#[from] LoroTreeError),
     #[error("Invalid argument ({0})")]
     ArgErr(Box<str>),
     // #[error("the data for key `{0}` is not available")]
@@ -42,6 +44,16 @@ pub enum LoroError {
     // Unknown,
 }
 
+#[derive(Error, Debug)]
+pub enum LoroTreeError {
+    #[error("`Cycle move` occurs when moving tree nodes.")]
+    CyclicMoveError,
+    #[error("The parent of tree node is not found {0:?}")]
+    TreeNodeParentNotFound(TreeID),
+    #[error("TreeID {0:?} doesn't exist")]
+    TreeNodeNotExist(TreeID),
+}
+
 #[cfg(feature = "wasm")]
 pub mod wasm {
     use wasm_bindgen::JsValue;

crates/loro-common/src/lib.rs

@@ -2,15 +2,18 @@ use std::{fmt::Display, sync::Arc};
 
 use arbitrary::Arbitrary;
 use enum_as_inner::EnumAsInner;
+
+use fxhash::FxHashMap;
 use serde::{Deserialize, Serialize};
 mod error;
 mod id;
 mod span;
 mod value;
 
-pub use error::{LoroError, LoroResult};
+pub use error::{LoroError, LoroResult, LoroTreeError};
 pub use span::*;
 pub use value::LoroValue;
+
 use zerovec::ule::AsULE;
 pub type PeerID = u64;
 pub type Counter = i32;
@@ -58,6 +61,7 @@ pub enum ContainerType {
     Text,
     Map,
     List,
+    Tree,
     // TODO: Users can define their own container types.
     // Custom(u16),
 }
@@ -70,6 +74,7 @@ impl AsULE for ContainerType {
             ContainerType::Map => 1,
             ContainerType::List => 2,
             ContainerType::Text => 3,
+            ContainerType::Tree => 4,
         }
     }
 
@@ -78,6 +83,7 @@ impl AsULE for ContainerType {
             1 => ContainerType::Map,
             2 => ContainerType::List,
             3 => ContainerType::Text,
+            4 => ContainerType::Tree,
             _ => unreachable!(),
         }
     }
@@ -89,6 +95,12 @@ impl ContainerType {
             ContainerType::Map => LoroValue::Map(Arc::new(Default::default())),
             ContainerType::List => LoroValue::List(Arc::new(Default::default())),
             ContainerType::Text => LoroValue::String(Arc::new(Default::default())),
+            ContainerType::Tree => {
+                let mut map: FxHashMap<String, LoroValue> = FxHashMap::default();
+                map.insert("roots".to_string(), LoroValue::List(vec![].into()));
+                map.insert("deleted".to_string(), LoroValue::List(vec![].into()));
+                map.into()
+            }
         }
     }
 
@@ -97,6 +109,7 @@ impl ContainerType {
             ContainerType::Map => 1,
             ContainerType::List => 2,
             ContainerType::Text => 3,
+            ContainerType::Tree => 4,
         }
     }
 
@@ -105,6 +118,7 @@ impl ContainerType {
             1 => ContainerType::Map,
             2 => ContainerType::List,
             3 => ContainerType::Text,
+            4 => ContainerType::Tree,
             _ => unreachable!(),
         }
     }
@@ -133,6 +147,7 @@ mod container {
                 ContainerType::Map => "Map",
                 ContainerType::List => "List",
                 ContainerType::Text => "Text",
+                ContainerType::Tree => "Tree",
             })
         }
     }
@@ -227,10 +242,119 @@ mod container {
                 "Map" => Ok(ContainerType::Map),
                 "List" => Ok(ContainerType::List),
                 "Text" => Ok(ContainerType::Text),
+                "Tree" => Ok(ContainerType::Tree),
                 _ => Err(LoroError::DecodeError(
                     ("Unknown container type".to_string() + value).into(),
                 )),
             }
         }
     }
 }
+
+/// In movable tree, we use a specific [`TreeID`] to represent the root of **ALL** non-existent tree nodes.
+///
+/// When we create some tree node and then we checkout the previous vision, we need to delete it from the state.
+/// If the parent of node is [`UNEXIST_TREE_ROOT`], we could infer this node is first created and delete it from the state directly,
+/// instead of moving it to the [`DELETED_TREE_ROOT`].
+///
+/// This root only can be old parent of node.
+pub const UNEXIST_TREE_ROOT: Option<TreeID> = Some(TreeID {
+    peer: PeerID::MAX,
+    counter: Counter::MAX - 1,
+});
+
+/// In movable tree, we use a specific [`TreeID`] to represent the root of **ALL** deleted tree node.
+///
+/// Deletion operation is equivalent to move target tree node to [`DELETED_TREE_ROOT`].
+pub const DELETED_TREE_ROOT: Option<TreeID> = Some(TreeID {
+    peer: PeerID::MAX,
+    counter: Counter::MAX,
+});
+
+/// Each node of movable tree has a unique [`TreeID`] generated by Loro.
+///
+/// To further represent the metadata (a MapContainer) associated with each node,
+/// we also use [`TreeID`] as [`ID`] portion of [`ContainerID`].
+/// This not only allows for convenient association of metadata with each node,
+/// but also ensures the uniqueness of the MapContainer.
+///
+/// Special ID:
+/// - [`DELETED_TREE_ROOT`]: the root of all deleted nodes. To get it by [`TreeID::delete_root()`]
+#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
+pub struct TreeID {
+    pub peer: PeerID,
+    pub counter: Counter,
+}
+
+impl TreeID {
+    /// return [`DELETED_TREE_ROOT`]
+    pub const fn delete_root() -> Option<Self> {
+        DELETED_TREE_ROOT
+    }
+
+    /// return `true` if the `TreeID` is deleted root
+    pub fn is_deleted_root(target: Option<TreeID>) -> bool {
+        target == DELETED_TREE_ROOT
+    }
+
+    pub const fn unexist_root() -> Option<Self> {
+        UNEXIST_TREE_ROOT
+    }
+
+    /// return `true` if the `TreeID` is non-existent root
+    pub fn is_unexist_root(target: Option<TreeID>) -> bool {
+        target == UNEXIST_TREE_ROOT
+    }
+
+    pub fn from_id(id: ID) -> Self {
+        Self {
+            peer: id.peer,
+            counter: id.counter,
+        }
+    }
+
+    pub fn id(&self) -> ID {
+        ID {
+            peer: self.peer,
+            counter: self.counter,
+        }
+    }
+}
+
+impl Display for TreeID {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.id().fmt(f)
+    }
+}
+
+impl TryFrom<&str> for TreeID {
+    type Error = ();
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        let mut parts = value.split('@');
+        let counter = parts.next().ok_or(())?.parse().map_err(|_| ())?;
+        let peer = parts.next().ok_or(())?.parse().map_err(|_| ())?;
+        Ok(TreeID { peer, counter })
+    }
+}
+
+#[cfg(feature = "wasm")]
+pub mod wasm {
+    use crate::TreeID;
+    use wasm_bindgen::JsValue;
+    impl From<TreeID> for JsValue {
+        fn from(value: TreeID) -> Self {
+            JsValue::from_str(&format!("{}", value.id()))
+        }
+    }
+
+    impl TryFrom<JsValue> for TreeID {
+        type Error = ();
+        fn try_from(value: JsValue) -> Result<Self, Self::Error> {
+            let id = value.as_string().unwrap();
+            let mut parts = id.split('@');
+            let counter = parts.next().ok_or(())?.parse().map_err(|_| ())?;
+            let peer = parts.next().ok_or(())?.parse().map_err(|_| ())?;
+            Ok(TreeID { peer, counter })
+        }
+    }
+}

crates/loro-internal/benches/tree.rs

@@ -0,0 +1,94 @@
+use criterion::{criterion_group, criterion_main, Criterion};
+#[cfg(feature = "test_utils")]
+mod tree {
+    use super::*;
+    use loro_internal::LoroDoc;
+    use rand::{rngs::StdRng, Rng};
+
+    pub fn tree_move(c: &mut Criterion) {
+        let mut b = c.benchmark_group("movable tree");
+        b.sample_size(10);
+        b.bench_function("10^3 tree move 10^5", |b| {
+            let loro = LoroDoc::default();
+            let tree = loro.get_tree("tree");
+            let mut ids = vec![];
+            let size = 1000;
+            for _ in 0..size {
+                ids.push(loro.with_txn(|txn| tree.create(txn)).unwrap())
+            }
+            let mut rng: StdRng = rand::SeedableRng::seed_from_u64(0);
+            let n = 100000;
+            b.iter(|| {
+                let mut txn = loro.txn().unwrap();
+                for _ in 0..n {
+                    let i = rng.gen::<usize>() % size;
+                    let j = rng.gen::<usize>() % size;
+                    tree.mov(&mut txn, ids[i], ids[j]).unwrap_or_default();
+                }
+                drop(txn)
+            })
+        });
+
+        b.bench_function("1000 node checkout 10^3", |b| {
+            let mut loro = LoroDoc::default();
+            let tree = loro.get_tree("tree");
+            let mut ids = vec![];
+            let mut versions = vec![];
+            let size = 1000;
+            for _ in 0..size {
+                ids.push(loro.with_txn(|txn| tree.create(txn)).unwrap())
+            }
+            let mut rng: StdRng = rand::SeedableRng::seed_from_u64(0);
+            let mut n = 1000;
+            while n > 0 {
+                let i = rng.gen::<usize>() % size;
+                let j = rng.gen::<usize>() % size;
+                if loro.with_txn(|txn| tree.mov(txn, ids[i], ids[j])).is_ok() {
+                    versions.push(loro.oplog_frontiers());
+                    n -= 1;
+                };
+            }
+            b.iter(|| {
+                for _ in 0..1000 {
+                    let i = rng.gen::<usize>() % 1000;
+                    let f = &versions[i];
+                    loro.checkout(f).unwrap();
+                }
+            })
+        });
+
+        b.bench_function("300 deep node random checkout 10^3", |b| {
+            let depth = 300;
+            let mut loro = LoroDoc::default();
+            let tree = loro.get_tree("tree");
+            let mut ids = vec![];
+            let mut versions = vec![];
+            let id1 = loro.with_txn(|txn| tree.create(txn)).unwrap();
+            ids.push(id1);
+            versions.push(loro.oplog_frontiers());
+            for _ in 1..depth {
+                let id = loro
+                    .with_txn(|txn| tree.create_and_mov(txn, *ids.last().unwrap()))
+                    .unwrap();
+                ids.push(id);
+                versions.push(loro.oplog_frontiers());
+            }
+            let mut rng: StdRng = rand::SeedableRng::seed_from_u64(0);
+            b.iter(|| {
+                for _ in 0..1000 {
+                    let i = rng.gen::<usize>() % depth;
+                    let f = &versions[i];
+                    loro.checkout(f).unwrap();
+                }
+            })
+        });
+    }
+}
+
+pub fn dumb(_c: &mut Criterion) {}
+
+#[cfg(feature = "test_utils")]
+criterion_group!(benches, tree::tree_move);
+#[cfg(not(feature = "test_utils"))]
+criterion_group!(benches, dumb);
+criterion_main!(benches);

crates/loro-internal/examples/tree.rs

@@ -0,0 +1,26 @@
+use std::time::Instant;
+
+use loro_internal::LoroDoc;
+use rand::{rngs::StdRng, Rng};
+
+fn main() {
+    let s = Instant::now();
+    let loro = LoroDoc::default();
+    let tree = loro.get_tree("tree");
+    let mut ids = vec![];
+    let size = 10000;
+    for _ in 0..size {
+        ids.push(loro.with_txn(|txn| tree.create(txn)).unwrap())
+    }
+    let mut rng: StdRng = rand::SeedableRng::seed_from_u64(0);
+    let n = 1000000;
+
+    let mut txn = loro.txn().unwrap();
+    for _ in 0..n {
+        let i = rng.gen::<usize>() % size;
+        let j = rng.gen::<usize>() % size;
+        tree.mov(&mut txn, ids[i], ids[j]).unwrap_or_default();
+    }
+    drop(txn);
+    println!("{} ms", s.elapsed().as_millis());
+}

crates/loro-internal/fuzz/Cargo.toml

@@ -47,3 +47,9 @@ name = "import"
 path = "fuzz_targets/import.rs"
 test = false
 doc = false
+
+[[bin]]
+name = "tree"
+path = "fuzz_targets/tree.rs"
+test = false
+doc = false

crates/loro-internal/fuzz/fuzz_targets/tree.rs

@@ -0,0 +1,5 @@
+#![no_main]
+use libfuzzer_sys::fuzz_target;
+use loro_internal::fuzz::tree::{test_multi_sites, Action};
+
+fuzz_target!(|actions: Vec<Action>| { test_multi_sites(5, &mut actions.clone()) });