fix(core): provide a way to reuse cached graph in CI (#29156)

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## Current Behavior
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## Expected Behavior
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## Related Issue(s)
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Fixes #

packages/nx/src/project-graph/affected/locators/project-glob-changes.ts

@@ -9,8 +9,20 @@ import { getPlugins } from '../../plugins/get-plugins';
 
 export const getTouchedProjectsFromProjectGlobChanges: TouchedProjectLocator =
   async (touchedFiles, projectGraphNodes): Promise<string[]> => {
-    const plugins = await getPlugins();
-    const globPattern = combineGlobPatterns(configurationGlobs(plugins));
+    const globPattern = await (async () => {
+      // TODO: We need a quicker way to get patterns that should not
+      // require starting up plugin workers
+      if (process.env.NX_FORCE_REUSE_CACHED_GRAPH === 'true') {
+        return combineGlobPatterns([
+          '**/package.json',
+          '**/project.json',
+          'project.json',
+          'package.json',
+        ]);
+      }
+      const plugins = await getPlugins();
+      return combineGlobPatterns(configurationGlobs(plugins));
+    })();
 
     const touchedProjects = new Set<string>();
     for (const touchedFile of touchedFiles) {

packages/nx/src/project-graph/build-project-graph.ts

@@ -72,6 +72,16 @@ export function getFileMap(): {
   }
 }
 
+export function hydrateFileMap(
+  fileMap: FileMap,
+  allWorkspaceFiles: FileData[],
+  rustReferences: NxWorkspaceFilesExternals
+) {
+  storedFileMap = fileMap;
+  storedAllWorkspaceFiles = allWorkspaceFiles;
+  storedRustReferences = rustReferences;
+}
+
 export async function buildProjectGraphUsingProjectFileMap(
   projectRootMap: Record<string, ProjectConfiguration>,
   externalNodes: Record<string, ProjectGraphExternalNode>,

packages/nx/src/project-graph/project-graph.ts

@@ -12,7 +12,10 @@ import { fileExists } from '../utils/fileutils';
 import { output } from '../utils/output';
 import { stripIndents } from '../utils/strip-indents';
 import { workspaceRoot } from '../utils/workspace-root';
-import { buildProjectGraphUsingProjectFileMap } from './build-project-graph';
+import {
+  buildProjectGraphUsingProjectFileMap,
+  hydrateFileMap,
+} from './build-project-graph';
 import {
   AggregateProjectGraphError,
   isAggregateProjectGraphError,
@@ -30,6 +33,7 @@ import {
   retrieveWorkspaceFiles,
 } from './utils/retrieve-workspace-files';
 import { getPlugins } from './plugins/get-plugins';
+import { logger } from '../utils/logger';
 
 /**
  * Synchronously reads the latest cached copy of the workspace's ProjectGraph.
@@ -229,6 +233,25 @@ export async function createProjectGraphAsync(
     resetDaemonClient: false,
   }
 ): Promise<ProjectGraph> {
+  if (process.env.NX_FORCE_REUSE_CACHED_GRAPH === 'true') {
+    try {
+      const graph = readCachedProjectGraph();
+      const projectRootMap = Object.fromEntries(
+        Object.entries(graph.nodes).map(([project, { data }]) => [
+          data.root,
+          project,
+        ])
+      );
+      const { allWorkspaceFiles, fileMap, rustReferences } =
+        await retrieveWorkspaceFiles(workspaceRoot, projectRootMap);
+      hydrateFileMap(fileMap, allWorkspaceFiles, rustReferences);
+      return graph;
+      // If no cached graph is found, we will fall through to the normal flow
+    } catch (e) {
+      logger.verbose('Unable to use cached project graph', e);
+    }
+  }
+
   const projectGraphAndSourceMaps = await createProjectGraphAndSourceMapsAsync(
     opts
   );