cache per-folder module resolutions during construction of the program (#13030)

src/compiler/diagnosticMessages.json

@@ -2945,6 +2945,10 @@
         "category": "Message",
         "code": 6146
     },
+    "Resolution for module '{0}' was found in cache": {
+        "category": "Message",
+        "code": 6147
+    },    
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",
         "code": 7005

src/compiler/moduleNameResolver.ts

@@ -293,33 +293,69 @@ namespace ts {
         return result;
     }
 
-    export function resolveModuleName(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations {
+    /**
+     * Cached module resolutions per containing directory.
+     * This assumes that any module id will have the same resolution for sibling files located in the same folder.
+     */
+    export interface ModuleResolutionCache {
+        getOrCreateCacheForDirectory(directoryName: string): Map<ResolvedModuleWithFailedLookupLocations>;
+    }
+
+    export function createModuleResolutionCache(currentDirectory: string, getCanonicalFileName: (s: string) => string) {
+        const map = createFileMap<Map<ResolvedModuleWithFailedLookupLocations>>();
+
+        return { getOrCreateCacheForDirectory };
+
+        function getOrCreateCacheForDirectory(directoryName: string) {
+            const path = toPath(directoryName, currentDirectory, getCanonicalFileName);
+            let perFolderCache = map.get(path);
+            if (!perFolderCache) {
+                perFolderCache = createMap<ResolvedModuleWithFailedLookupLocations>();
+                map.set(path, perFolderCache);
+            }
+            return perFolderCache;
+        }
+    }
+
+    export function resolveModuleName(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost, cache?: ModuleResolutionCache): ResolvedModuleWithFailedLookupLocations {
         const traceEnabled = isTraceEnabled(compilerOptions, host);
         if (traceEnabled) {
             trace(host, Diagnostics.Resolving_module_0_from_1, moduleName, containingFile);
         }
+        let perFolderCache = cache && cache.getOrCreateCacheForDirectory(getDirectoryPath(containingFile));
+        let result = perFolderCache && perFolderCache[moduleName];
 
-        let moduleResolution = compilerOptions.moduleResolution;
-        if (moduleResolution === undefined) {
-            moduleResolution = getEmitModuleKind(compilerOptions) === ModuleKind.CommonJS ? ModuleResolutionKind.NodeJs : ModuleResolutionKind.Classic;
+        if (result) {
             if (traceEnabled) {
-                trace(host, Diagnostics.Module_resolution_kind_is_not_specified_using_0, ModuleResolutionKind[moduleResolution]);
+                trace(host, Diagnostics.Resolution_for_module_0_was_found_in_cache, moduleName);
             }
         }
         else {
-            if (traceEnabled) {
-                trace(host, Diagnostics.Explicitly_specified_module_resolution_kind_Colon_0, ModuleResolutionKind[moduleResolution]);
+            let moduleResolution = compilerOptions.moduleResolution;
+            if (moduleResolution === undefined) {
+                moduleResolution = getEmitModuleKind(compilerOptions) === ModuleKind.CommonJS ? ModuleResolutionKind.NodeJs : ModuleResolutionKind.Classic;
+                if (traceEnabled) {
+                    trace(host, Diagnostics.Module_resolution_kind_is_not_specified_using_0, ModuleResolutionKind[moduleResolution]);
+                }
+            }
+            else {
+                if (traceEnabled) {
+                    trace(host, Diagnostics.Explicitly_specified_module_resolution_kind_Colon_0, ModuleResolutionKind[moduleResolution]);
+                }
             }
-        }
 
-        let result: ResolvedModuleWithFailedLookupLocations;
-        switch (moduleResolution) {
-            case ModuleResolutionKind.NodeJs:
-                result = nodeModuleNameResolver(moduleName, containingFile, compilerOptions, host);
-                break;
-            case ModuleResolutionKind.Classic:
-                result = classicNameResolver(moduleName, containingFile, compilerOptions, host);
-                break;
+            switch (moduleResolution) {
+                case ModuleResolutionKind.NodeJs:
+                    result = nodeModuleNameResolver(moduleName, containingFile, compilerOptions, host);
+                    break;
+                case ModuleResolutionKind.Classic:
+                    result = classicNameResolver(moduleName, containingFile, compilerOptions, host);
+                    break;
+            }
+
+            if (perFolderCache) {
+                perFolderCache[moduleName] = result;
+            }
         }
 
         if (traceEnabled) {

src/compiler/program.ts

@@ -325,6 +325,7 @@ namespace ts {
         // Map storing if there is emit blocking diagnostics for given input
         const hasEmitBlockingDiagnostics = createFileMap<boolean>(getCanonicalFileName);
 
+        let moduleResolutionCache: ModuleResolutionCache;
         let resolveModuleNamesWorker: (moduleNames: string[], containingFile: string) => ResolvedModuleFull[];
         if (host.resolveModuleNames) {
             resolveModuleNamesWorker = (moduleNames, containingFile) => host.resolveModuleNames(moduleNames, containingFile).map(resolved => {
@@ -338,7 +339,8 @@ namespace ts {
             });
         }
         else {
-            const loader = (moduleName: string, containingFile: string) => resolveModuleName(moduleName, containingFile, options, host).resolvedModule;
+            moduleResolutionCache = createModuleResolutionCache(currentDirectory, x => host.getCanonicalFileName(x));
+            const loader = (moduleName: string, containingFile: string) => resolveModuleName(moduleName, containingFile, options, host, moduleResolutionCache).resolvedModule;
             resolveModuleNamesWorker = (moduleNames, containingFile) => loadWithLocalCache(moduleNames, containingFile, loader);
         }
 
@@ -391,6 +393,9 @@ namespace ts {
             }
         }
 
+        // unconditionally set moduleResolutionCache to undefined to avoid unnecessary leaks
+        moduleResolutionCache = undefined;
+
         // unconditionally set oldProgram to undefined to prevent it from being captured in closure
         oldProgram = undefined;
 

tests/baselines/reference/cacheResolutions.js

@@ -0,0 +1,27 @@
+//// [tests/cases/compiler/cacheResolutions.ts] ////
+
+//// [app.ts]
+
+export let x = 1;
+
+//// [lib1.ts]
+export let x = 1;
+
+//// [lib2.ts]
+export let x = 1;
+
+//// [app.js]
+define(["require", "exports"], function (require, exports) {
+    "use strict";
+    exports.x = 1;
+});
+//// [lib1.js]
+define(["require", "exports"], function (require, exports) {
+    "use strict";
+    exports.x = 1;
+});
+//// [lib2.js]
+define(["require", "exports"], function (require, exports) {
+    "use strict";
+    exports.x = 1;
+});

tests/baselines/reference/cacheResolutions.symbols

@@ -0,0 +1,13 @@
+=== /a/b/c/app.ts ===
+
+export let x = 1;
+>x : Symbol(x, Decl(app.ts, 1, 10))
+
+=== /a/b/c/lib1.ts ===
+export let x = 1;
+>x : Symbol(x, Decl(lib1.ts, 0, 10))
+
+=== /a/b/c/lib2.ts ===
+export let x = 1;
+>x : Symbol(x, Decl(lib2.ts, 0, 10))
+

tests/baselines/reference/cacheResolutions.trace.json

@@ -0,0 +1,43 @@
+[
+    "======== Resolving module 'tslib' from '/a/b/c/app.ts'. ========",
+    "Module resolution kind is not specified, using 'Classic'.",
+    "File '/a/b/c/tslib.ts' does not exist.",
+    "File '/a/b/c/tslib.tsx' does not exist.",
+    "File '/a/b/c/tslib.d.ts' does not exist.",
+    "File '/a/b/tslib.ts' does not exist.",
+    "File '/a/b/tslib.tsx' does not exist.",
+    "File '/a/b/tslib.d.ts' does not exist.",
+    "File '/a/tslib.ts' does not exist.",
+    "File '/a/tslib.tsx' does not exist.",
+    "File '/a/tslib.d.ts' does not exist.",
+    "File '/tslib.ts' does not exist.",
+    "File '/tslib.tsx' does not exist.",
+    "File '/tslib.d.ts' does not exist.",
+    "File '/a/b/c/node_modules/@types/tslib.d.ts' does not exist.",
+    "File '/a/b/c/node_modules/@types/tslib/package.json' does not exist.",
+    "File '/a/b/c/node_modules/@types/tslib/index.d.ts' does not exist.",
+    "File '/a/b/node_modules/@types/tslib.d.ts' does not exist.",
+    "File '/a/b/node_modules/@types/tslib/package.json' does not exist.",
+    "File '/a/b/node_modules/@types/tslib/index.d.ts' does not exist.",
+    "File '/a/node_modules/@types/tslib.d.ts' does not exist.",
+    "File '/a/node_modules/@types/tslib/package.json' does not exist.",
+    "File '/a/node_modules/@types/tslib/index.d.ts' does not exist.",
+    "File '/node_modules/@types/tslib.d.ts' does not exist.",
+    "File '/node_modules/@types/tslib/package.json' does not exist.",
+    "File '/node_modules/@types/tslib/index.d.ts' does not exist.",
+    "File '/a/b/c/tslib.js' does not exist.",
+    "File '/a/b/c/tslib.jsx' does not exist.",
+    "File '/a/b/tslib.js' does not exist.",
+    "File '/a/b/tslib.jsx' does not exist.",
+    "File '/a/tslib.js' does not exist.",
+    "File '/a/tslib.jsx' does not exist.",
+    "File '/tslib.js' does not exist.",
+    "File '/tslib.jsx' does not exist.",
+    "======== Module name 'tslib' was not resolved. ========",
+    "======== Resolving module 'tslib' from '/a/b/c/lib1.ts'. ========",
+    "Resolution for module 'tslib' was found in cache",
+    "======== Module name 'tslib' was not resolved. ========",
+    "======== Resolving module 'tslib' from '/a/b/c/lib2.ts'. ========",
+    "Resolution for module 'tslib' was found in cache",
+    "======== Module name 'tslib' was not resolved. ========"
+]

tests/baselines/reference/cacheResolutions.types

@@ -0,0 +1,16 @@
+=== /a/b/c/app.ts ===
+
+export let x = 1;
+>x : number
+>1 : 1
+
+=== /a/b/c/lib1.ts ===
+export let x = 1;
+>x : number
+>1 : 1
+
+=== /a/b/c/lib2.ts ===
+export let x = 1;
+>x : number
+>1 : 1
+

tests/baselines/reference/typeReferenceDirectives12.trace.json

@@ -16,9 +16,7 @@
     "Resolving real path for '/types/lib/index.d.ts', result '/types/lib/index.d.ts'",
     "======== Type reference directive 'lib' was successfully resolved to '/types/lib/index.d.ts', primary: true. ========",
     "======== Resolving module './main' from '/mod1.ts'. ========",
-    "Module resolution kind is not specified, using 'NodeJs'.",
-    "Loading module as file / folder, candidate module location '/main'.",
-    "File '/main.ts' exist - use it as a name resolution result.",
+    "Resolution for module './main' was found in cache",
     "======== Module name './main' was successfully resolved to '/main.ts'. ========",
     "======== Resolving type reference directive 'lib', containing file '/__inferred type names__.ts', root directory '/types'. ========",
     "Resolving with primary search path '/types'",

tests/baselines/reference/typeReferenceDirectives9.trace.json

@@ -16,9 +16,7 @@
     "Resolving real path for '/types/lib/index.d.ts', result '/types/lib/index.d.ts'",
     "======== Type reference directive 'lib' was successfully resolved to '/types/lib/index.d.ts', primary: true. ========",
     "======== Resolving module './main' from '/mod1.ts'. ========",
-    "Module resolution kind is not specified, using 'NodeJs'.",
-    "Loading module as file / folder, candidate module location '/main'.",
-    "File '/main.ts' exist - use it as a name resolution result.",
+    "Resolution for module './main' was found in cache",
     "======== Module name './main' was successfully resolved to '/main.ts'. ========",
     "======== Resolving type reference directive 'lib', containing file '/__inferred type names__.ts', root directory '/types'. ========",
     "Resolving with primary search path '/types'",

tests/cases/compiler/cacheResolutions.ts

@@ -0,0 +1,12 @@
+// @module: amd
+// @importHelpers: true
+// @traceResolution: true
+
+// @filename: /a/b/c/app.ts
+export let x = 1;
+
+// @filename: /a/b/c/lib1.ts
+export let x = 1;
+
+// @filename: /a/b/c/lib2.ts
+export let x = 1;