refactor synchoronizer

backend/src/services/document/ws_actor.rs

@@ -13,7 +13,8 @@ use flowy_collaboration::{
         ClientRevisionWSDataType as ClientRevisionWSDataTypePB,
         Revision as RevisionPB,
     },
-    server_document::{RevisionSyncResponse, RevisionUser, ServerDocumentManager},
+    server_document::ServerDocumentManager,
+    synchronizer::{RevisionSyncResponse, RevisionUser},
 };
 use futures::stream::StreamExt;
 use std::sync::Arc;

backend/src/services/folder/ws_actor.rs

@@ -11,7 +11,8 @@ use flowy_collaboration::{
         ClientRevisionWSData as ClientRevisionWSDataPB,
         ClientRevisionWSDataType as ClientRevisionWSDataTypePB,
     },
-    server_document::{RevisionSyncResponse, RevisionUser, ServerDocumentManager},
+    server_document::ServerDocumentManager,
+    synchronizer::{RevisionSyncResponse, RevisionUser},
 };
 use futures::stream::StreamExt;
 use std::sync::Arc;

backend/src/services/web_socket/entities/message.rs

@@ -1,6 +1,6 @@
 use actix::Message;
 use bytes::Bytes;
-use flowy_collaboration::entities::ws::{ClientRevisionWSData, ServerRevisionWSData};
+use flowy_collaboration::entities::ws_data::{ClientRevisionWSData, ServerRevisionWSData};
 use lib_ws::{WSModule, WebSocketRawMessage};
 use std::convert::TryInto;
 

frontend/rust-lib/flowy-document/src/controller.rs

@@ -5,7 +5,7 @@ use dashmap::DashMap;
 use flowy_collaboration::entities::{
     doc::{DocumentDelta, DocumentId},
     revision::{md5, RepeatedRevision, Revision},
-    ws::ServerRevisionWSData,
+    ws_data::ServerRevisionWSData,
 };
 use flowy_database::ConnectionPool;
 use flowy_error::FlowyResult;

frontend/rust-lib/flowy-document/src/core/web_socket.rs

@@ -7,7 +7,7 @@ use bytes::Bytes;
 use flowy_collaboration::{
     entities::{
         revision::{RepeatedRevision, Revision, RevisionRange},
-        ws::{ClientRevisionWSData, NewDocumentUser, ServerRevisionWSData, ServerRevisionWSDataType},
+        ws_data::{ClientRevisionWSData, NewDocumentUser, ServerRevisionWSData, ServerRevisionWSDataType},
     },
     errors::CollaborateResult,
 };

frontend/rust-lib/flowy-net/src/local_server/persistence.rs

@@ -27,25 +27,25 @@ pub trait RevisionCloudStorage: Send + Sync {
     ) -> BoxResultFuture<(), CollaborateError>;
 }
 
-pub(crate) struct LocalRevisionCloudPersistence {
+pub(crate) struct LocalDocumentCloudPersistence {
     // For the moment, we use memory to cache the data, it will be implemented with other storage.
     // Like the Firestore,Dropbox.etc.
     storage: Arc<dyn RevisionCloudStorage>,
 }
 
-impl Debug for LocalRevisionCloudPersistence {
+impl Debug for LocalDocumentCloudPersistence {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result { f.write_str("LocalRevisionCloudPersistence") }
 }
 
-impl std::default::Default for LocalRevisionCloudPersistence {
+impl std::default::Default for LocalDocumentCloudPersistence {
     fn default() -> Self {
-        LocalRevisionCloudPersistence {
+        LocalDocumentCloudPersistence {
             storage: Arc::new(MemoryDocumentCloudStorage::default()),
         }
     }
 }
 
-impl DocumentCloudPersistence for LocalRevisionCloudPersistence {
+impl DocumentCloudPersistence for LocalDocumentCloudPersistence {
     fn read_document(&self, doc_id: &str) -> BoxResultFuture<DocumentInfo, CollaborateError> {
         let storage = self.storage.clone();
         let doc_id = doc_id.to_owned();

frontend/rust-lib/flowy-net/src/local_server/server.rs

@@ -1,15 +1,16 @@
-use crate::local_server::persistence::LocalRevisionCloudPersistence;
+use crate::local_server::persistence::LocalDocumentCloudPersistence;
 use async_stream::stream;
 use bytes::Bytes;
 use flowy_collaboration::{
     client_document::default::initial_delta_string,
     entities::{
         doc::{CreateDocParams, DocumentId, DocumentInfo, ResetDocumentParams},
-        ws::{ClientRevisionWSData, ClientRevisionWSDataType},
+        ws_data::{ClientRevisionWSData, ClientRevisionWSDataType},
     },
     errors::CollaborateError,
     protobuf::ClientRevisionWSData as ClientRevisionWSDataPB,
-    server_document::*,
+    server_document::ServerDocumentManager,
+    synchronizer::{RevisionSyncResponse, RevisionUser},
 };
 use flowy_core::module::WorkspaceCloudService;
 use flowy_error::{internal_error, FlowyError};
@@ -35,7 +36,7 @@ impl LocalServer {
         client_ws_sender: mpsc::UnboundedSender<WebSocketRawMessage>,
         client_ws_receiver: broadcast::Sender<WebSocketRawMessage>,
     ) -> Self {
-        let persistence = Arc::new(LocalRevisionCloudPersistence::default());
+        let persistence = Arc::new(LocalDocumentCloudPersistence::default());
         let doc_manager = Arc::new(ServerDocumentManager::new(persistence));
         let stop_tx = RwLock::new(None);
 

frontend/rust-lib/flowy-sdk/src/deps_resolve/core_deps.rs

@@ -1,6 +1,6 @@
 use backend_service::configuration::ClientServerConfiguration;
 use bytes::Bytes;
-use flowy_collaboration::entities::ws::ClientRevisionWSData;
+use flowy_collaboration::entities::ws_data::ClientRevisionWSData;
 use flowy_core::{
     controller::FolderManager,
     errors::{internal_error, FlowyError},

frontend/rust-lib/flowy-sdk/src/deps_resolve/document_deps.rs

@@ -1,6 +1,6 @@
 use backend_service::configuration::ClientServerConfiguration;
 use bytes::Bytes;
-use flowy_collaboration::entities::ws::ClientRevisionWSData;
+use flowy_collaboration::entities::ws_data::ClientRevisionWSData;
 use flowy_database::ConnectionPool;
 use flowy_document::{
     context::{DocumentContext, DocumentUser},

frontend/rust-lib/flowy-sync/src/ws_manager.rs

@@ -2,7 +2,7 @@ use async_stream::stream;
 use bytes::Bytes;
 use flowy_collaboration::entities::{
     revision::{RevId, RevisionRange},
-    ws::{ClientRevisionWSData, NewDocumentUser, ServerRevisionWSData, ServerRevisionWSDataType},
+    ws_data::{ClientRevisionWSData, NewDocumentUser, ServerRevisionWSData, ServerRevisionWSDataType},
 };
 use flowy_error::{internal_error, FlowyError, FlowyResult};
 use futures_util::stream::StreamExt;

shared-lib/flowy-collaboration/src/entities/mod.rs

@@ -1,4 +1,4 @@
 pub mod doc;
 pub mod parser;
 pub mod revision;
-pub mod ws;
+pub mod ws_data;

shared-lib/flowy-collaboration/src/lib.rs

@@ -3,5 +3,7 @@ pub mod entities;
 pub mod errors;
 pub mod protobuf;
 pub mod server_document;
+pub mod synchronizer;
 pub mod util;
+
 pub use lib_ot::rich_text::RichTextDelta;

shared-lib/flowy-collaboration/src/server_document/document_manager.rs

@@ -1,20 +1,23 @@
 use crate::{
-    entities::{doc::DocumentInfo, ws::ServerRevisionWSDataBuilder},
+    entities::{doc::DocumentInfo, ws_data::ServerRevisionWSDataBuilder},
     errors::{internal_error, CollaborateError, CollaborateResult},
     protobuf::{ClientRevisionWSData, RepeatedRevision as RepeatedRevisionPB, Revision as RevisionPB},
-    server_document::{document_pad::ServerDocument, RevisionSyncResponse, RevisionSynchronizer, RevisionUser},
+    server_document::document_pad::ServerDocument,
+    synchronizer::{RevisionSyncPersistence, RevisionSyncResponse, RevisionSynchronizer, RevisionUser},
 };
 use async_stream::stream;
 use dashmap::DashMap;
 use futures::stream::StreamExt;
 use lib_infra::future::BoxResultFuture;
-use lib_ot::rich_text::RichTextDelta;
+use lib_ot::rich_text::{RichTextAttributes, RichTextDelta};
 use std::{collections::HashMap, fmt::Debug, sync::Arc};
 use tokio::{
     sync::{mpsc, oneshot, RwLock},
     task::spawn_blocking,
 };
 
+type RichTextRevisionSynchronizer = RevisionSynchronizer<RichTextAttributes>;
+
 pub trait DocumentCloudPersistence: Send + Sync + Debug {
     fn read_document(&self, doc_id: &str) -> BoxResultFuture<DocumentInfo, CollaborateError>;
 
@@ -173,6 +176,28 @@ struct OpenDocHandle {
     users: DashMap<String, Arc<dyn RevisionUser>>,
 }
 
+impl RevisionSyncPersistence for Arc<dyn DocumentCloudPersistence> {
+    fn read_revisions(
+        &self,
+        object_id: &str,
+        rev_ids: Option<Vec<i64>>,
+    ) -> BoxResultFuture<Vec<RevisionPB>, CollaborateError> {
+        (**self).read_revisions(object_id, rev_ids)
+    }
+
+    fn save_revisions(&self, repeated_revision: RepeatedRevisionPB) -> BoxResultFuture<(), CollaborateError> {
+        (**self).save_revisions(repeated_revision)
+    }
+
+    fn reset_object(
+        &self,
+        object_id: &str,
+        repeated_revision: RepeatedRevisionPB,
+    ) -> BoxResultFuture<(), CollaborateError> {
+        (**self).reset_document(object_id, repeated_revision)
+    }
+}
+
 impl OpenDocHandle {
     fn new(doc: DocumentInfo, persistence: Arc<dyn DocumentCloudPersistence>) -> Result<Self, CollaborateError> {
         let doc_id = doc.doc_id.clone();
@@ -180,12 +205,8 @@ impl OpenDocHandle {
         let users = DashMap::new();
 
         let delta = RichTextDelta::from_bytes(&doc.text)?;
-        let synchronizer = Arc::new(RevisionSynchronizer::new(
-            &doc.doc_id,
-            doc.rev_id,
-            ServerDocument::from_delta(delta),
-            persistence,
-        ));
+        let sync_object = ServerDocument::from_delta(&doc_id, delta);
+        let synchronizer = Arc::new(RichTextRevisionSynchronizer::new(doc.rev_id, sync_object, persistence));
 
         let queue = DocumentCommandQueue::new(&doc.doc_id, receiver, synchronizer)?;
         tokio::task::spawn(queue.run());
@@ -263,14 +284,14 @@ enum DocumentCommand {
 struct DocumentCommandQueue {
     pub doc_id: String,
     receiver: Option<mpsc::Receiver<DocumentCommand>>,
-    synchronizer: Arc<RevisionSynchronizer>,
+    synchronizer: Arc<RichTextRevisionSynchronizer>,
 }
 
 impl DocumentCommandQueue {
     fn new(
         doc_id: &str,
         receiver: mpsc::Receiver<DocumentCommand>,
-        synchronizer: Arc<RevisionSynchronizer>,
+        synchronizer: Arc<RichTextRevisionSynchronizer>,
     ) -> Result<Self, CollaborateError> {
         Ok(Self {
             doc_id: doc_id.to_owned(),

shared-lib/flowy-collaboration/src/server_document/document_pad.rs

@@ -1,39 +1,42 @@
-use crate::{client_document::InitialDocumentText, errors::CollaborateError};
-use lib_ot::{core::*, rich_text::RichTextDelta};
+use crate::{client_document::InitialDocumentText, errors::CollaborateError, synchronizer::RevisionSyncObject};
+use lib_ot::{
+    core::*,
+    rich_text::{RichTextAttributes, RichTextDelta},
+};
 
 pub struct ServerDocument {
+    doc_id: String,
     delta: RichTextDelta,
 }
 
 impl ServerDocument {
-    pub fn new<C: InitialDocumentText>() -> Self { Self::from_delta(C::initial_delta()) }
+    #[allow(dead_code)]
+    pub fn new<C: InitialDocumentText>(doc_id: &str) -> Self { Self::from_delta(doc_id, C::initial_delta()) }
 
-    pub fn from_delta(delta: RichTextDelta) -> Self { ServerDocument { delta } }
-
-    pub fn from_json(json: &str) -> Result<Self, CollaborateError> {
-        let delta = RichTextDelta::from_json(json)?;
-        Ok(Self::from_delta(delta))
+    pub fn from_delta(doc_id: &str, delta: RichTextDelta) -> Self {
+        let doc_id = doc_id.to_owned();
+        ServerDocument { doc_id, delta }
     }
 
-    pub fn to_json(&self) -> String { self.delta.to_json() }
-
-    pub fn to_bytes(&self) -> Vec<u8> { self.delta.clone().to_bytes().to_vec() }
-
-    pub fn to_plain_string(&self) -> String { self.delta.apply("").unwrap() }
+    pub fn is_empty<C: InitialDocumentText>(&self) -> bool { self.delta == C::initial_delta() }
+}
 
-    pub fn delta(&self) -> &RichTextDelta { &self.delta }
+impl RevisionSyncObject<RichTextAttributes> for ServerDocument {
+    fn id(&self) -> &str { &self.doc_id }
 
-    pub fn md5(&self) -> String {
-        let bytes = self.to_bytes();
-        format!("{:x}", md5::compute(bytes))
+    fn compose(&mut self, other: &RichTextDelta) -> Result<(), CollaborateError> {
+        tracing::trace!("{} compose {}", &self.delta.to_json(), other.to_json());
+        let new_delta = self.delta.compose(other)?;
+        self.delta = new_delta;
+        Ok(())
     }
 
-    pub fn compose_delta(&mut self, delta: RichTextDelta) -> Result<(), CollaborateError> {
-        // tracing::trace!("{} compose {}", &self.delta.to_json(), delta.to_json());
-        let composed_delta = self.delta.compose(&delta)?;
-        self.delta = composed_delta;
-        Ok(())
+    fn transform(&self, other: &RichTextDelta) -> Result<(RichTextDelta, RichTextDelta), CollaborateError> {
+        let value = self.delta.transform(other)?;
+        Ok(value)
     }
 
-    pub fn is_empty<C: InitialDocumentText>(&self) -> bool { self.delta == C::initial_delta() }
+    fn to_json(&self) -> String { self.delta.to_json() }
+
+    fn set_delta(&mut self, new_delta: Delta<RichTextAttributes>) { self.delta = new_delta; }
 }

shared-lib/flowy-collaboration/src/server_document/mod.rs

@@ -1,6 +1,4 @@
 mod document_manager;
 mod document_pad;
-mod revision_sync;
 
 pub use document_manager::*;
-pub use revision_sync::*;

shared-lib/flowy-collaboration/src/server_document/revision_sync.rs

@@ -1,13 +1,14 @@
 use crate::{
     entities::{
         revision::RevisionRange,
-        ws::{ServerRevisionWSData, ServerRevisionWSDataBuilder},
+        ws_data::{ServerRevisionWSData, ServerRevisionWSDataBuilder},
     },
     errors::CollaborateError,
     protobuf::{RepeatedRevision as RepeatedRevisionPB, Revision as RevisionPB},
     server_document::{document_pad::ServerDocument, DocumentCloudPersistence},
     util::*,
 };
+use lib_infra::future::BoxResultFuture;
 use lib_ot::{core::OperationTransformable, rich_text::RichTextDelta};
 use parking_lot::RwLock;
 use std::{
@@ -25,6 +26,16 @@ pub trait RevisionUser: Send + Sync + Debug {
     fn receive(&self, resp: RevisionSyncResponse);
 }
 
+pub trait RevisionSyncObject {
+    type SyncObject;
+
+    fn read_revisions(&self, rev_ids: Option<Vec<i64>>) -> BoxResultFuture<Vec<RevisionPB>, CollaborateError>;
+
+    fn save_revisions(&self, repeated_revision: RepeatedRevisionPB) -> BoxResultFuture<(), CollaborateError>;
+
+    fn reset_object(&self, repeated_revision: RepeatedRevisionPB) -> BoxResultFuture<(), CollaborateError>;
+}
+
 pub enum RevisionSyncResponse {
     Pull(ServerRevisionWSData),
     Push(ServerRevisionWSData),

shared-lib/flowy-collaboration/src/synchronizer.rs

@@ -0,0 +1,260 @@
+use crate::{
+    entities::{
+        revision::RevisionRange,
+        ws_data::{ServerRevisionWSData, ServerRevisionWSDataBuilder},
+    },
+    errors::CollaborateError,
+    protobuf::{RepeatedRevision as RepeatedRevisionPB, Revision as RevisionPB},
+    util::*,
+};
+use lib_infra::future::BoxResultFuture;
+use lib_ot::core::{Attributes, Delta, OperationTransformable};
+use parking_lot::RwLock;
+use serde::de::DeserializeOwned;
+use std::{
+    cmp::Ordering,
+    fmt::Debug,
+    sync::{
+        atomic::{AtomicI64, Ordering::SeqCst},
+        Arc,
+    },
+    time::Duration,
+};
+
+pub trait RevisionUser: Send + Sync + Debug {
+    fn user_id(&self) -> String;
+    fn receive(&self, resp: RevisionSyncResponse);
+}
+
+pub trait RevisionSyncPersistence: Send + Sync + 'static {
+    fn read_revisions(
+        &self,
+        object_id: &str,
+        rev_ids: Option<Vec<i64>>,
+    ) -> BoxResultFuture<Vec<RevisionPB>, CollaborateError>;
+
+    fn save_revisions(&self, repeated_revision: RepeatedRevisionPB) -> BoxResultFuture<(), CollaborateError>;
+
+    fn reset_object(
+        &self,
+        object_id: &str,
+        repeated_revision: RepeatedRevisionPB,
+    ) -> BoxResultFuture<(), CollaborateError>;
+}
+
+pub trait RevisionSyncObject<T: Attributes>: Send + Sync + 'static {
+    fn id(&self) -> &str;
+    fn compose(&mut self, other: &Delta<T>) -> Result<(), CollaborateError>;
+    fn transform(&self, other: &Delta<T>) -> Result<(Delta<T>, Delta<T>), CollaborateError>;
+    fn to_json(&self) -> String;
+    fn set_delta(&mut self, new_delta: Delta<T>);
+}
+
+pub enum RevisionSyncResponse {
+    Pull(ServerRevisionWSData),
+    Push(ServerRevisionWSData),
+    Ack(ServerRevisionWSData),
+}
+
+pub struct RevisionSynchronizer<T: Attributes> {
+    object_id: String,
+    rev_id: AtomicI64,
+    object: Arc<RwLock<dyn RevisionSyncObject<T>>>,
+    persistence: Arc<dyn RevisionSyncPersistence>,
+}
+
+impl<T> RevisionSynchronizer<T>
+where
+    T: Attributes + DeserializeOwned + serde::Serialize + 'static,
+{
+    pub fn new<S, P>(rev_id: i64, sync_object: S, persistence: P) -> RevisionSynchronizer<T>
+    where
+        S: RevisionSyncObject<T>,
+        P: RevisionSyncPersistence,
+    {
+        let object = Arc::new(RwLock::new(sync_object));
+        let persistence = Arc::new(persistence);
+        let object_id = object.read().id().to_owned();
+        RevisionSynchronizer {
+            object_id,
+            rev_id: AtomicI64::new(rev_id),
+            object,
+            persistence,
+        }
+    }
+
+    #[tracing::instrument(level = "debug", skip(self, user, repeated_revision), err)]
+    pub async fn sync_revisions(
+        &self,
+        user: Arc<dyn RevisionUser>,
+        repeated_revision: RepeatedRevisionPB,
+    ) -> Result<(), CollaborateError> {
+        let doc_id = self.object_id.clone();
+        if repeated_revision.get_items().is_empty() {
+            // Return all the revisions to client
+            let revisions = self.persistence.read_revisions(&doc_id, None).await?;
+            let repeated_revision = repeated_revision_from_revision_pbs(revisions)?;
+            let data = ServerRevisionWSDataBuilder::build_push_message(&doc_id, repeated_revision);
+            user.receive(RevisionSyncResponse::Push(data));
+            return Ok(());
+        }
+
+        let server_base_rev_id = self.rev_id.load(SeqCst);
+        let first_revision = repeated_revision.get_items().first().unwrap().clone();
+        if self.is_applied_before(&first_revision, &self.persistence).await {
+            // Server has received this revision before, so ignore the following revisions
+            return Ok(());
+        }
+
+        match server_base_rev_id.cmp(&first_revision.rev_id) {
+            Ordering::Less => {
+                let server_rev_id = next(server_base_rev_id);
+                if server_base_rev_id == first_revision.base_rev_id || server_rev_id == first_revision.rev_id {
+                    // The rev is in the right order, just compose it.
+                    for revision in repeated_revision.get_items() {
+                        let _ = self.compose_revision(revision)?;
+                    }
+                    let _ = self.persistence.save_revisions(repeated_revision).await?;
+                } else {
+                    // The server document is outdated, pull the missing revision from the client.
+                    let range = RevisionRange {
+                        object_id: self.object_id.clone(),
+                        start: server_rev_id,
+                        end: first_revision.rev_id,
+                    };
+                    let msg = ServerRevisionWSDataBuilder::build_pull_message(&self.object_id, range);
+                    user.receive(RevisionSyncResponse::Pull(msg));
+                }
+            },
+            Ordering::Equal => {
+                // Do nothing
+                tracing::warn!("Applied revision rev_id is the same as cur_rev_id");
+            },
+            Ordering::Greater => {
+                // The client document is outdated. Transform the client revision delta and then
+                // send the prime delta to the client. Client should compose the this prime
+                // delta.
+                let from_rev_id = first_revision.rev_id;
+                let to_rev_id = server_base_rev_id;
+                let _ = self.push_revisions_to_user(user, from_rev_id, to_rev_id).await;
+            },
+        }
+        Ok(())
+    }
+
+    #[tracing::instrument(level = "trace", skip(self, user), fields(server_rev_id), err)]
+    pub async fn pong(&self, user: Arc<dyn RevisionUser>, client_rev_id: i64) -> Result<(), CollaborateError> {
+        let doc_id = self.object_id.clone();
+        let server_rev_id = self.rev_id();
+        tracing::Span::current().record("server_rev_id", &server_rev_id);
+
+        match server_rev_id.cmp(&client_rev_id) {
+            Ordering::Less => {
+                tracing::error!("Client should not send ping and the server should pull the revisions from the client")
+            },
+            Ordering::Equal => tracing::trace!("{} is up to date.", doc_id),
+            Ordering::Greater => {
+                // The client document is outdated. Transform the client revision delta and then
+                // send the prime delta to the client. Client should compose the this prime
+                // delta.
+                let from_rev_id = client_rev_id;
+                let to_rev_id = server_rev_id;
+                tracing::trace!("Push revisions to user");
+                let _ = self.push_revisions_to_user(user, from_rev_id, to_rev_id).await;
+            },
+        }
+        Ok(())
+    }
+
+    #[tracing::instrument(level = "debug", skip(self, repeated_revision), fields(doc_id), err)]
+    pub async fn reset(&self, repeated_revision: RepeatedRevisionPB) -> Result<(), CollaborateError> {
+        let doc_id = self.object_id.clone();
+        tracing::Span::current().record("doc_id", &doc_id.as_str());
+        let revisions: Vec<RevisionPB> = repeated_revision.get_items().to_vec();
+        let (_, rev_id) = pair_rev_id_from_revision_pbs(&revisions);
+        let delta = make_delta_from_revision_pb(revisions)?;
+        let _ = self.persistence.reset_object(&doc_id, repeated_revision).await?;
+        self.object.write().set_delta(delta);
+        let _ = self.rev_id.fetch_update(SeqCst, SeqCst, |_e| Some(rev_id));
+        Ok(())
+    }
+
+    pub fn object_json(&self) -> String { self.object.read().to_json() }
+
+    fn compose_revision(&self, revision: &RevisionPB) -> Result<(), CollaborateError> {
+        let delta = Delta::<T>::from_bytes(&revision.delta_data)?;
+        let _ = self.compose_delta(delta)?;
+        let _ = self.rev_id.fetch_update(SeqCst, SeqCst, |_e| Some(revision.rev_id));
+        Ok(())
+    }
+
+    #[tracing::instrument(level = "debug", skip(self, revision))]
+    fn transform_revision(&self, revision: &RevisionPB) -> Result<(Delta<T>, Delta<T>), CollaborateError> {
+        let cli_delta = Delta::<T>::from_bytes(&revision.delta_data)?;
+        let result = self.object.read().transform(&cli_delta)?;
+        Ok(result)
+    }
+
+    fn compose_delta(&self, delta: Delta<T>) -> Result<(), CollaborateError> {
+        if delta.is_empty() {
+            log::warn!("Composed delta is empty");
+        }
+
+        match self.object.try_write_for(Duration::from_millis(300)) {
+            None => log::error!("Failed to acquire write lock of document"),
+            Some(mut write_guard) => {
+                let _ = write_guard.compose(&delta)?;
+            },
+        }
+        Ok(())
+    }
+
+    pub(crate) fn rev_id(&self) -> i64 { self.rev_id.load(SeqCst) }
+
+    async fn is_applied_before(
+        &self,
+        new_revision: &RevisionPB,
+        persistence: &Arc<dyn RevisionSyncPersistence>,
+    ) -> bool {
+        let rev_ids = Some(vec![new_revision.rev_id]);
+        if let Ok(revisions) = persistence.read_revisions(&self.object_id, rev_ids).await {
+            if let Some(revision) = revisions.first() {
+                if revision.md5 == new_revision.md5 {
+                    return true;
+                }
+            }
+        };
+
+        false
+    }
+
+    async fn push_revisions_to_user(&self, user: Arc<dyn RevisionUser>, from: i64, to: i64) {
+        let rev_ids: Vec<i64> = (from..=to).collect();
+        let revisions = match self.persistence.read_revisions(&self.object_id, Some(rev_ids)).await {
+            Ok(revisions) => {
+                assert_eq!(
+                    revisions.is_empty(),
+                    false,
+                    "revisions should not be empty if the doc exists"
+                );
+                revisions
+            },
+            Err(e) => {
+                tracing::error!("{}", e);
+                vec![]
+            },
+        };
+
+        tracing::debug!("Push revision: {} -> {} to client", from, to);
+        match repeated_revision_from_revision_pbs(revisions) {
+            Ok(repeated_revision) => {
+                let data = ServerRevisionWSDataBuilder::build_push_message(&self.object_id, repeated_revision);
+                user.receive(RevisionSyncResponse::Push(data));
+            },
+            Err(e) => tracing::error!("{}", e),
+        }
+    }
+}
+
+#[inline]
+fn next(rev_id: i64) -> i64 { rev_id + 1 }

shared-lib/flowy-collaboration/src/util.rs

@@ -12,6 +12,8 @@ use std::{
     convert::TryInto,
     sync::atomic::{AtomicI64, Ordering::SeqCst},
 };
+use serde::de::DeserializeOwned;
+use lib_ot::core::{Attributes, Delta};
 
 #[inline]
 pub fn find_newline(s: &str) -> Option<usize> { s.find(NEW_LINE) }
@@ -57,10 +59,10 @@ pub fn make_delta_from_revisions(revisions: Vec<Revision>) -> CollaborateResult<
     Ok(delta)
 }
 
-pub fn make_delta_from_revision_pb(revisions: Vec<RevisionPB>) -> CollaborateResult<RichTextDelta> {
-    let mut new_delta = RichTextDelta::new();
+pub fn make_delta_from_revision_pb<T>(revisions: Vec<RevisionPB>) -> CollaborateResult<Delta<T>> where T: Attributes + DeserializeOwned {
+    let mut new_delta = Delta::<T>::new();
     for revision in revisions {
-        let delta = RichTextDelta::from_bytes(revision.delta_data).map_err(|e| {
+        let delta = Delta::<T>::from_bytes(revision.delta_data).map_err(|e| {
             let err_msg = format!("Deserialize remote revision failed: {:?}", e);
             CollaborateError::internal().context(err_msg)
         })?;