Saves children to avoid losing state on tree update

src/views/nodes/branchNode.ts

@@ -14,6 +14,8 @@ export class BranchNode extends ExplorerRefNode implements PageableExplorerNode
     readonly supportsPaging: boolean = true;
     maxCount: number | undefined;
 
+    private _children: ExplorerNode[] | undefined;
+
     constructor(
         public readonly branch: GitBranch,
         uri: GitUri,
@@ -45,35 +47,42 @@ export class BranchNode extends ExplorerRefNode implements PageableExplorerNode
     }
 
     async getChildren(): Promise<ExplorerNode[]> {
-        const log = await Container.git.getLog(this.uri.repoPath!, {
-            maxCount: this.maxCount || this.explorer.config.defaultItemLimit,
-            ref: this.ref
-        });
-        if (log === undefined) return [new MessageNode('No commits yet')];
-
-        const branches = await Container.git.getBranches(this.uri.repoPath);
-        // Get the sha length, since `git branch` can return variable length shas
-        const shaLength = branches[0].sha!.length;
-        const branchesBySha = Arrays.groupByFilterMap(
-            branches,
-            b => b.sha!,
-            b => (b.name === this.branch.name ? undefined : b.name)
-        );
-
-        const getBranchTips = (sha: string) => {
-            const branches = branchesBySha.get(sha.substr(0, shaLength));
-            if (branches === undefined || branches.length === 0) return undefined;
-            return branches.join(', ');
-        };
-
-        const children: (CommitNode | ShowMoreNode)[] = [
-            ...Iterables.map(log.commits.values(), c => new CommitNode(c, this.explorer, this.branch, getBranchTips))
-        ];
+        if (this._children === undefined) {
+            const log = await Container.git.getLog(this.uri.repoPath!, {
+                maxCount: this.maxCount || this.explorer.config.defaultItemLimit,
+                ref: this.ref
+            });
+            if (log === undefined) return [new MessageNode('No commits yet')];
+
+            const branches = await Container.git.getBranches(this.uri.repoPath);
+            // Get the sha length, since `git branch` can return variable length shas
+            const shaLength = branches[0].sha!.length;
+            const branchesBySha = Arrays.groupByFilterMap(
+                branches,
+                b => b.sha!,
+                b => (b.name === this.branch.name ? undefined : b.name)
+            );
+
+            const getBranchTips = (sha: string) => {
+                const branches = branchesBySha.get(sha.substr(0, shaLength));
+                if (branches === undefined || branches.length === 0) return undefined;
+                return branches.join(', ');
+            };
+
+            const children: (CommitNode | ShowMoreNode)[] = [
+                ...Iterables.map(
+                    log.commits.values(),
+                    c => new CommitNode(c, this.explorer, this.branch, getBranchTips)
+                )
+            ];
+
+            if (log.truncated) {
+                children.push(new ShowMoreNode('Commits', this, this.explorer));
+            }
 
-        if (log.truncated) {
-            children.push(new ShowMoreNode('Commits', this, this.explorer));
+            this._children = children;
         }
-        return children;
+        return this._children;
     }
 
     async getTreeItem(): Promise<TreeItem> {
@@ -129,4 +138,8 @@ export class BranchNode extends ExplorerRefNode implements PageableExplorerNode
 
         return item;
     }
+
+    refresh() {
+        this._children = undefined;
+    }
 }

src/views/nodes/branchesNode.ts

@@ -10,6 +10,8 @@ import { BranchOrTagFolderNode } from './branchOrTagFolderNode';
 import { ExplorerNode, ResourceType } from './explorerNode';
 
 export class BranchesNode extends ExplorerNode {
+    private _children: ExplorerNode[] | undefined;
+
     constructor(
         uri: GitUri,
         private readonly repo: Repository,
@@ -23,26 +25,32 @@ export class BranchesNode extends ExplorerNode {
     }
 
     async getChildren(): Promise<ExplorerNode[]> {
-        const branches = await this.repo.getBranches();
-        if (branches === undefined) return [];
-
-        branches.sort((a, b) => a.name.localeCompare(b.name));
-
-        // filter local branches
-        const branchNodes = [
-            ...Iterables.filterMap(branches, b => (b.remote ? undefined : new BranchNode(b, this.uri, this.explorer)))
-        ];
-        if (this.explorer.config.branches.layout === ExplorerBranchesLayout.List) return branchNodes;
-
-        const hierarchy = Arrays.makeHierarchical(
-            branchNodes,
-            n => (n.branch.detached ? [n.branch.name] : n.branch.getName().split('/')),
-            (...paths: string[]) => paths.join('/'),
-            this.explorer.config.files.compact
-        );
-
-        const root = new BranchOrTagFolderNode('branch', this.repo.path, '', undefined, hierarchy, this.explorer);
-        return root.getChildren();
+        if (this._children === undefined) {
+            const branches = await this.repo.getBranches();
+            if (branches === undefined) return [];
+
+            branches.sort((a, b) => a.name.localeCompare(b.name));
+
+            // filter local branches
+            const branchNodes = [
+                ...Iterables.filterMap(
+                    branches,
+                    b => (b.remote ? undefined : new BranchNode(b, this.uri, this.explorer))
+                )
+            ];
+            if (this.explorer.config.branches.layout === ExplorerBranchesLayout.List) return branchNodes;
+
+            const hierarchy = Arrays.makeHierarchical(
+                branchNodes,
+                n => (n.branch.detached ? [n.branch.name] : n.branch.getName().split('/')),
+                (...paths: string[]) => paths.join('/'),
+                this.explorer.config.files.compact
+            );
+
+            const root = new BranchOrTagFolderNode('branch', this.repo.path, '', undefined, hierarchy, this.explorer);
+            this._children = await root.getChildren();
+        }
+        return this._children;
     }
 
     async getTreeItem(): Promise<TreeItem> {
@@ -60,4 +68,8 @@ export class BranchesNode extends ExplorerNode {
 
         return item;
     }
+
+    refresh() {
+        this._children = undefined;
+    }
 }