fix(reviewing): fix memory error in pnpm why (#7122)

* fix(reviewing): fix memory error in `pnpm why`

* fix: update comments

* fix: add support for `--depth`

* fix: move implementation to `@pnpm/list`

* fix: revert changes in Dependencies Hierarchy

* fix: add pnpm to patch list

* refactor: rename functions to descriptive names

* refactor: rename `findEndLeafs` to `findEndLeaves`

.changeset/happy-lemons-smile.md

@@ -0,0 +1,6 @@
+---
+"@pnpm/list": patch
+"pnpm": patch
+---
+
+Fix memory error in `pnpm why` when the dependencies tree is too big, the command will now prune the tree to just 10 end leafs and now supports `--depth` argument.

reviewing/list/src/index.ts

@@ -6,6 +6,7 @@ import { renderJson } from './renderJson'
 import { renderParseable } from './renderParseable'
 import { renderTree } from './renderTree'
 import { type PackageDependencyHierarchy } from './types'
+import { pruneDependenciesTrees } from './pruneTree'
 
 export type { PackageNode } from '@pnpm/reviewing.dependencies-hierarchy'
 export { renderJson, renderParseable, renderTree }
@@ -105,8 +106,10 @@ export async function listForPackages (
 
   const pkgs = await searchForPackages(packages, projectPaths, opts)
 
+  const prunedPkgs = pruneDependenciesTrees(pkgs ?? null, 10)
+
   const print = getPrinter(opts.reportAs)
-  return print(pkgs, {
+  return print(prunedPkgs, {
     alwaysPrintRootPackage: opts.alwaysPrintRootPackage,
     depth: opts.depth,
     long: opts.long,

reviewing/list/src/pruneTree.ts

@@ -0,0 +1,78 @@
+import { type DependenciesHierarchy, type PackageNode } from '@pnpm/reviewing.dependencies-hierarchy'
+import { type PackageDependencyHierarchy } from './types'
+import { createHash } from 'crypto'
+
+export function pruneDependenciesTrees (trees: PackageDependencyHierarchy[] | null, limit: number): PackageDependencyHierarchy[] {
+  if (trees === null) {
+    return []
+  }
+
+  return trees.map((tree) => {
+    const endLeafPaths: PackageNode[][] = []
+    const visitedNodes = new Set<string>()
+
+    function findEndLeaves (node: PackageNode, path: PackageNode[]): void {
+      if (node.circular) {
+        return
+      }
+
+      const nodeId = `${node.name}@${node.version}`
+      if (visitedNodes.has(nodeId)) {
+        return
+      }
+
+      visitedNodes.add(nodeId)
+      const newPath = [...path, node]
+
+      if (!node.dependencies || node.dependencies.length === 0) {
+        endLeafPaths.push(newPath)
+        if (endLeafPaths.length >= limit) {
+          return
+        }
+      }
+
+      for (const child of node.dependencies ?? []) {
+        findEndLeaves(child, newPath)
+        if (endLeafPaths.length >= limit) {
+          return
+        }
+      }
+
+      visitedNodes.delete(nodeId)
+    }
+
+    if (tree.dependencies) {
+      for (const node of tree.dependencies) {
+        findEndLeaves(node, [])
+      }
+    }
+
+    const firstNPaths = endLeafPaths.slice(0, limit)
+    const map = new Map<string, PackageNode>()
+    const newTree: DependenciesHierarchy = { dependencies: [] }
+
+    for (const path of firstNPaths) {
+      let currentDependencies: PackageNode[] = newTree.dependencies!
+      let pathSoFar = ''
+
+      for (const node of path) {
+        pathSoFar += `${node.name}@${node.version},`
+        const id = createHash('sha256').update(pathSoFar).digest('hex')
+        let existingNode = map.get(id)
+
+        if (!existingNode) {
+          existingNode = { ...node, dependencies: [] }
+          currentDependencies.push(existingNode)
+          map.set(id, existingNode)
+        }
+
+        currentDependencies = existingNode.dependencies!
+      }
+    }
+
+    return {
+      ...tree,
+      dependencies: newTree.dependencies,
+    }
+  })
+}

reviewing/plugin-commands-listing/src/why.ts

@@ -8,6 +8,7 @@ import { handler as list, type ListCommandOptions } from './list'
 
 export function rcOptionsTypes () {
   return pick([
+    'depth',
     'dev',
     'global-dir',
     'global',
@@ -79,6 +80,10 @@ For options that may be used with `-r`, see "pnpm help recursive"',
             description: "Don't display packages from `optionalDependencies`",
             name: '--no-optional',
           },
+          {
+            name: '--depth <number>',
+            description: 'Max display depth of the dependency graph',
+          },
           OPTIONS.globalDir,
           ...UNIVERSAL_OPTIONS,
         ],
@@ -103,7 +108,7 @@ export async function handler (
     ...opts,
     cliOptions: {
       ...(opts.cliOptions ?? {}),
-      depth: Infinity,
+      depth: opts.depth ?? Infinity,
     },
   }, params)
 }