fix bug starting jupyter on compute server

compute server jupyter kernels relied on a subtle behavior of the
cursors table.

src/packages/frontend/compute/manager.ts

@@ -53,7 +53,7 @@ export class ComputeServersManager extends EventEmitter {
 
   getComputeServers = () => {
     const servers = {};
-    const cursors = this.sync_db.get_cursors().toJS();
+    const cursors = this.sync_db.get_cursors({ excludeSelf: 'never' }).toJS();
     for (const client_id in cursors) {
       const server = cursors[client_id];
       servers[decodeUUIDtoNum(client_id)] = {

src/packages/frontend/frame-editors/code-editor/actions.ts

@@ -1150,9 +1150,11 @@ export class Actions<
     let cursors: Map<string, List<Map<string, any>>> = Map();
     this._syncstring
       .get_cursors({
-        excludeSelf: !redux
+        excludeSelf: redux
           .getStore("account")
-          .getIn(["editor_settings", "show_my_other_cursors"]),
+          .getIn(["editor_settings", "show_my_other_cursors"])
+          ? "heuristic"
+          : "always",
       })
       .forEach((info, account_id) => {
         info.get("locs").forEach((loc) => {
@@ -1198,7 +1200,7 @@ export class Actions<
     }
     const omit_lines: SetMap = {};
     const cursors = this._syncstring.get_cursors?.({
-      excludeSelf: false,
+      excludeSelf: "never",
       maxAge: 3 * 60 * 1000,
     }); // there are situations where get_cursors isn't defined (seen this).
     if (cursors) {

src/packages/frontend/frame-editors/jupyter-editor/actions.ts

@@ -562,7 +562,7 @@ export class JupyterEditorActions extends BaseActions<JupyterEditorState> {
 
   gotoUser(account_id: string, frameId?: string) {
     const cursors = this.jupyter_actions.syncdb
-      .get_cursors({ maxAge: 0 })
+      .get_cursors({ maxAge: 0, excludeSelf: "never" })
       ?.toJS();
     if (cursors == null) return; // no info
     const locs = cursors[account_id]?.locs;

src/packages/frontend/frame-editors/whiteboard-editor/actions.ts

@@ -1023,7 +1023,9 @@ export class Actions<T extends State = State> extends BaseActions<T | State> {
   }
 
   gotoUser(account_id: string, frameId?: string) {
-    const cursors = this._syncstring.get_cursors({ maxAge: 0 })?.toJS();
+    const cursors = this._syncstring
+      .get_cursors({ maxAge: 0, excludeSelf: "never" })
+      ?.toJS();
     if (cursors == null) return; // no info
     const locs = cursors[account_id]?.locs;
     for (const loc of locs) {

src/packages/frontend/jupyter/browser-actions.ts

@@ -326,9 +326,11 @@ export class JupyterActions extends JupyterActions0 {
     ) {
       return;
     }
-    const excludeSelf = !this.redux
+    const excludeSelf = this.redux
       .getStore("account")
-      .getIn(["editor_settings", "show_my_other_cursors"]);
+      .getIn(["editor_settings", "show_my_other_cursors"])
+      ? "heuristic"
+      : "always";
     const cursors = this.syncdb.get_cursors({ excludeSelf });
     const cells = this.cursor_manager.process(this.store.get("cells"), cursors);
     if (cells != null) {

src/packages/frontend/syncdoc.coffee

@@ -447,7 +447,7 @@ class SynchronizedDocument2 extends SynchronizedDocument
     delete_trailing_whitespace: =>
         cm = @focused_codemirror()
         omit_lines = {}
-        @_syncstring.get_cursors()?.map (x, _) =>
+        @_syncstring.get_cursors(excludeSelf:'never')?.map (x, _) =>
             x.get('locs')?.map (loc) =>
                 y = loc.get('y')
                 if y?

src/packages/sync/editor/generic/sync-doc.ts

@@ -530,7 +530,7 @@ export class SyncDoc extends EventEmitter {
       maxAge: COMPUTE_THRESH_MS,
       // don't exclude self since getComputeServerId called from the compute
       // server also to know if it is the chosen one.
-      excludeSelf: false,
+      excludeSelf: "never",
     });
     const dbg = this.dbg("getComputeServerId");
     dbg("num cursors = ", cursors.size);
@@ -549,6 +549,7 @@ export class SyncDoc extends EventEmitter {
         }
       }
     }
+
     return isFinite(minId) ? minId : 0;
   };
 
@@ -1884,13 +1885,21 @@ export class SyncDoc extends EventEmitter {
 
   /* Returns *immutable* Map from account_id to list
      of cursor positions, if cursors are enabled.
+
+     - excludeSelf: do not include our own cursor
+     - maxAge: only include cursors that have been updated with maxAge ms from now.
   */
-  public get_cursors = ({
+  get_cursors = ({
     maxAge = 60 * 1000,
-    excludeSelf = true,
+    // excludeSelf:
+    // 'always' -- *always* exclude self
+    // 'never' -- never exclude self
+    // 'heuristic' -- exclude self is older than last set from here, e.g., useful on
+    // frontend so we don't see our own cursor unless more than one browser.
+    excludeSelf = "always",
   }: {
     maxAge?: number;
-    excludeSelf?: boolean;
+    excludeSelf?: "always" | "never" | "heuristic";
   } = {}): Map<string, any> => {
     this.assert_not_closed("get_cursors");
     if (!this.cursors) {
@@ -1901,12 +1910,15 @@ export class SyncDoc extends EventEmitter {
     }
     const account_id: string = this.client_id();
     let map = this.cursor_map;
-    if (
-      (excludeSelf && map.has(account_id)) ||
-      this.cursor_last_time >=
-        (map.getIn([account_id, "time"], new Date(0)) as Date)
-    ) {
-      map = map.delete(account_id);
+    if (map.has(account_id) && excludeSelf != "never") {
+      if (
+        excludeSelf == "always" ||
+        (excludeSelf == "heuristic" &&
+          this.cursor_last_time >=
+            (map.getIn([account_id, "time"], new Date(0)) as Date))
+      ) {
+        map = map.delete(account_id);
+      }
     }
     // Remove any old cursors, where "old" is by default more than maxAge old.
     const now = Date.now();
@@ -1939,7 +1951,7 @@ export class SyncDoc extends EventEmitter {
   /* Set settings map.  Used for custom configuration just for
      this one file, e.g., overloading the spell checker language.
    */
-  public set_settings = async (obj): Promise<void> => {
+  set_settings = async (obj): Promise<void> => {
     this.assert_is_ready("set_settings");
     await this.set_syncstring_table({
       settings: obj,