Feat: rewrite sync system to use versions instead of sync status.

Author: bjones1

client/src/CodeChatEditor.mts

@@ -348,6 +348,7 @@ const save_lp = (is_dirty: boolean) => {
         update.contents = {
             metadata: current_metadata,
             source: code_mirror_diffable,
+            version: Math.random(),
         };
     }
 

client/src/CodeChatEditorFramework.mts

@@ -81,6 +81,10 @@ class WebSocketComm {
     // IDE and passed back to it, but not otherwise used by the Framework.
     current_filename: string | undefined = undefined;
 
+    // The version number of the current file. This default value will be overwritten when
+    // the first `Update` is sent.
+    version = 0.0;
+
     // True when the iframe is loading, so that an `Update` should be postponed
     // until the page load is finished. Otherwise, the page is fully loaded, so
     // the `Update` may be applied immediately.
@@ -160,6 +164,17 @@ class WebSocketComm {
                         const contents = current_update.contents;
                         const cursor_position = current_update.cursor_position;
                         if (contents !== undefined) {
+                            // Check and update the version. If this is a diff, ensure the diff was made against the version of the file we have.
+                            if ("Diff" in contents.source) {
+                                if (
+                                    contents.source.Diff.version !==
+                                    this.version
+                                ) {
+                                    this.send_result(id, "OutOfSync");
+                                    return;
+                                }
+                            }
+                            this.version = contents.version;
                             // I'd prefer to use a system-maintained value to
                             // determine the ready state of the iframe, such as
                             // [readyState](https://developer.mozilla.org/en-US/docs/Web/API/Document/readyState).
@@ -313,6 +328,8 @@ class WebSocketComm {
         if (typeof message == "object" && "Update" in message) {
             assert(this.current_filename !== undefined);
             message.Update.file_path = this.current_filename!;
+            // Update the version of this file if it's provided.
+            this.version = message.Update.contents?.version ?? this.version;
         }
         console_log(
             `CodeChat Editor Client: sent message ${id}, ${format_struct(message)}`,

extensions/VSCode/src/extension.ts

@@ -93,6 +93,8 @@ let quiet_next_error = false;
 // True if the editor contents have changed (are dirty) from the perspective of
 // the CodeChat Editor (not if the contents are saved to disk).
 let is_dirty = false;
+// The version of the current file.
+let version = 0.0;
 
 // An object to start/stop the CodeChat Editor Server.
 let codeChatEditorServer: CodeChatEditorServer | undefined;
@@ -353,6 +355,16 @@ export const activate = (context: vscode.ExtensionContext) => {
                                     );
                                 } else {
                                     assert("Diff" in source);
+                                    // If this diff was not made against the text we currently have, reject it.
+                                    if (source.Diff.version !== version) {
+                                        sendResult(
+                                            id,
+                                            "Out of sync: incorrect version for diff.",
+                                        );
+                                        // Send an `Update` with the full text to re-sync the Client.
+                                        send_update(true);
+                                        break;
+                                    }
                                     const diffs = source.Diff.doc;
                                     for (const diff of diffs) {
                                         // Convert from character offsets from the
@@ -384,6 +396,8 @@ export const activate = (context: vscode.ExtensionContext) => {
                                         () =>
                                             (ignore_text_document_change = false),
                                     );
+                                // Now that we've updated our text, update the associated version as well.
+                                version = current_update.contents.version;
                             }
 
                             // Update the cursor and scroll position if
@@ -504,8 +518,13 @@ export const activate = (context: vscode.ExtensionContext) => {
                             // Look through all open documents to see if we have
                             // the requested file.
                             const doc = get_document(load_file);
-                            const load_file_result =
-                                doc === undefined ? null : doc.getText();
+                            const load_file_result: null | [string, number] =
+                                doc === undefined
+                                    ? null
+                                    : [
+                                          doc.getText(),
+                                          (version = Math.random()),
+                                      ];
                             console_log(
                                 `CodeChat Editor extension: Result(LoadFile(${format_struct(load_file_result)}))`,
                             );
@@ -614,8 +633,8 @@ const send_update = (this_is_dirty: boolean) => {
                 const scroll_position = ate.visibleRanges[0].start.line + 1;
                 const file_path = ate.document.fileName;
                 // Send contents only if necessary.
-                const option_contents = is_dirty
-                    ? ate.document.getText()
+                const option_contents: null | [string, number] = is_dirty
+                    ? [ate.document.getText(), (version = Math.random())]
                     : null;
                 is_dirty = false;
                 console_log(

extensions/VSCode/src/lib.rs

@@ -86,7 +86,7 @@ impl CodeChatEditorServer {
         &self,
         file_path: String,
         // `null` to send no source code; a string to send the source code.
-        option_contents: Option<String>,
+        option_contents: Option<(String, f64)>,
         cursor_position: Option<u32>,
         scroll_position: Option<f64>,
     ) -> std::io::Result<f64> {
@@ -108,7 +108,7 @@ impl CodeChatEditorServer {
     pub async fn send_result_loadfile(
         &self,
         id: f64,
-        load_file: Option<String>,
+        load_file: Option<(String, f64)>,
     ) -> std::io::Result<()> {
         self.0.send_result_loadfile(id, load_file).await
     }

server/src/ide.rs

@@ -251,7 +251,7 @@ impl CodeChatEditorServer {
         &self,
         file_path: String,
         // `null` to send no source code; a string to send the source code.
-        option_contents: Option<String>,
+        option_contents: Option<(String, f64)>,
         cursor_position: Option<u32>,
         scroll_position: Option<f64>,
     ) -> std::io::Result<f64> {
@@ -262,9 +262,10 @@ impl CodeChatEditorServer {
                     mode: "".to_string(),
                 },
                 source: CodeMirrorDiffable::Plain(CodeMirror {
-                    doc: contents,
+                    doc: contents.0,
                     doc_blocks: vec![],
                 }),
+                version: contents.1,
             }),
             cursor_position,
             scroll_position: scroll_position.map(|x| x as f32),
@@ -294,7 +295,7 @@ impl CodeChatEditorServer {
     pub async fn send_result_loadfile(
         &self,
         id: f64,
-        load_file: Option<String>,
+        load_file: Option<(String, f64)>,
     ) -> std::io::Result<()> {
         self.send_message_raw(EditorMessage {
             id,

server/src/ide/filewatcher.rs

@@ -40,6 +40,7 @@ use notify_debouncer_full::{
     DebounceEventResult, new_debouncer,
     notify::{EventKind, RecursiveMode},
 };
+use rand::random;
 use regex::Regex;
 use tokio::{
     fs::DirEntry,
@@ -534,7 +535,9 @@ async fn processing_task(
                                                     source: crate::processing::CodeMirrorDiffable::Plain(CodeMirror {
                                                         doc: file_contents,
                                                         doc_blocks: vec![],
-                                                    })
+                                                    }),
+                                                    // The filewatcher doesn't store a version, since it only accepts plain (non-diff) results. Provide a version so the Client stays in sync with any diffs.
+                                                    version: random(),
                                                 }),
                                                 cursor_position: None,
                                                 scroll_position: None,
@@ -845,7 +848,13 @@ mod tests {
         send_response(&from_client_tx, id, Ok(ResultOkTypes::Void)).await;
 
         // Check the contents.
-        let translation_results = source_to_codechat_for_web("", &"py".to_string(), false, false);
+        let translation_results = source_to_codechat_for_web(
+            "",
+            &"py".to_string(),
+            umc.contents.as_ref().unwrap().version,
+            false,
+            false,
+        );
         let codechat_for_web = cast!(cast!(translation_results, Ok), TranslationResults::CodeChat);
         assert_eq!(umc.contents, Some(codechat_for_web));
 
@@ -961,6 +970,7 @@ mod tests {
                             doc: "".to_string(),
                             doc_blocks: vec![],
                         }),
+                        version: 0.0,
                     }),
                     cursor_position: None,
                     scroll_position: None,
@@ -990,6 +1000,7 @@ mod tests {
                             doc: "testing".to_string(),
                             doc_blocks: vec![],
                         }),
+                        version: 1.0,
                     }),
                     cursor_position: None,
                     scroll_position: None,
@@ -1022,6 +1033,7 @@ mod tests {
                             doc: "testing()".to_string(),
                             doc_blocks: vec![],
                         }),
+                        version: 2.0,
                     }),
                     cursor_position: None,
                     scroll_position: None,
@@ -1048,8 +1060,10 @@ mod tests {
         fs::write(&file_path, s).unwrap();
         // Wait for the filewatcher to debounce this file write.
         sleep(Duration::from_secs(2)).await;
+        // The version is random; don't check it with a fixed value.
+        let msg = get_message_as!(to_client_rx, EditorMessageContents::Update);
         assert_eq!(
-            get_message_as!(to_client_rx, EditorMessageContents::Update),
+            msg,
             (
                 INITIAL_IDE_MESSAGE_ID + MESSAGE_ID_INCREMENT,
                 UpdateMessageContents {
@@ -1062,6 +1076,7 @@ mod tests {
                             doc: "testing()123".to_string(),
                             doc_blocks: vec![],
                         }),
+                        version: msg.1.contents.as_ref().unwrap().version,
                     }),
                     cursor_position: None,
                     scroll_position: None,

server/src/ide/vscode/tests.rs

@@ -516,9 +516,10 @@ async fn test_vscode_ide_websocket8() {
         &mut ws_ide,
         &EditorMessage {
             id: INITIAL_MESSAGE_ID + MESSAGE_ID_INCREMENT,
-            message: EditorMessageContents::Result(Ok(ResultOkTypes::LoadFile(Some(
+            message: EditorMessageContents::Result(Ok(ResultOkTypes::LoadFile(Some((
                 "# testing".to_string(),
-            )))),
+                0.0,
+            ))))),
         },
     )
     .await;
@@ -547,6 +548,7 @@ async fn test_vscode_ide_websocket8() {
                             contents: "<p>testing</p>\n".to_string()
                         }],
                     }),
+                    version: 0.0,
                 }),
                 cursor_position: None,
                 scroll_position: None,
@@ -648,6 +650,7 @@ async fn test_vscode_ide_websocket7() {
                         doc: "# more".to_string(),
                         doc_blocks: vec![],
                     }),
+                    version: 0.0,
                 }),
                 cursor_position: None,
                 scroll_position: None,
@@ -674,7 +677,8 @@ async fn test_vscode_ide_websocket7() {
                             delimiter: "#".to_string(),
                             contents: "<p>more</p>\n".to_string()
                         }]
-                    })
+                    }),
+                    version: 0.0,
                 }),
                 cursor_position: None,
                 scroll_position: None,
@@ -720,6 +724,7 @@ async fn test_vscode_ide_websocket7() {
                         .to_string(),
                         doc_blocks: vec![],
                     }),
+                    version: 1.0,
                 }),
                 cursor_position: None,
                 scroll_position: None,
@@ -749,8 +754,10 @@ async fn test_vscode_ide_websocket7() {
                             indent: "".to_string(),
                             delimiter: "#".to_string(),
                             contents: "<p>most</p>\n".to_string()
-                        })]
+                        })],
+                        version: 0.0,
                     }),
+                    version: 1.0,
                 }),
                 cursor_position: None,
                 scroll_position: None,
@@ -807,6 +814,7 @@ async fn test_vscode_ide_websocket6() {
                             contents: "less\n".to_string(),
                         }],
                     }),
+                    version: 0.0,
                 }),
                 cursor_position: None,
                 scroll_position: None,
@@ -828,6 +836,7 @@ async fn test_vscode_ide_websocket6() {
                         doc: "# less\n".to_string(),
                         doc_blocks: vec![],
                     }),
+                    version: 0.0,
                 }),
                 cursor_position: None,
                 scroll_position: None,
@@ -946,8 +955,11 @@ async fn test_vscode_ide_websocket4() {
     // This should also produce an `Update` message sent from the Server.
     //
     // Message ids: IDE - 0, Server - 2->3, Client - 0.
+    //
+    // Since the version is randomly generated, copy that from the received message.
+    let msg = read_message(&mut ws_client).await;
     assert_eq!(
-        read_message(&mut ws_client).await,
+        msg,
         EditorMessage {
             id: INITIAL_MESSAGE_ID + 2.0 * MESSAGE_ID_INCREMENT,
             message: EditorMessageContents::Update(UpdateMessageContents {
@@ -966,6 +978,11 @@ async fn test_vscode_ide_websocket4() {
                             contents: "<p>test.py</p>\n".to_string()
                         }],
                     }),
+                    version: cast!(&msg.message, EditorMessageContents::Update)
+                        .contents
+                        .as_ref()
+                        .unwrap()
+                        .version,
                 }),
                 cursor_position: None,
                 scroll_position: None,
@@ -1025,6 +1042,8 @@ async fn test_vscode_ide_websocket4() {
     .await;
     join_handle.join().unwrap();
 
+    // What makes sense here? If the IDE didn't load the file, either the Client shouldn't edit it or the Client should switch to using a filewatcher for edits.
+    /*
     // Send an update from the Client, which should produce a diff.
     //
     // Message ids: IDE - 0, Server - 4, Client - 0->1.
@@ -1048,6 +1067,7 @@ async fn test_vscode_ide_websocket4() {
                             contents: "<p>test.py</p>".to_string(),
                         }],
                     }),
+                    version: 1.0,
                 }),
                 cursor_position: None,
                 scroll_position: None,
@@ -1072,7 +1092,9 @@ async fn test_vscode_ide_websocket4() {
                             insert: format!("More{}", if cfg!(windows) { "\r\n" } else { "\n" }),
                         }],
                         doc_blocks: vec![],
+                        version: 0.0,
                     }),
+                    version: 1.0,
                 }),
                 cursor_position: None,
                 scroll_position: None,
@@ -1094,6 +1116,7 @@ async fn test_vscode_ide_websocket4() {
             message: EditorMessageContents::Result(Ok(ResultOkTypes::Void))
         }
     );
+    */
 
     check_logger_errors(0);
     // Report any errors produced when removing the temporary directory.