Merge pull request #15261 from aozgaa/moduleReuse

Reuse Module Resolutions from Unchanged Files

Author: aozgaa

src/compiler/core.ts

@@ -251,6 +251,15 @@ namespace ts {
         }
     }
 
+    export function zipToMap<T>(keys: string[], values: T[]): Map<T> {
+        Debug.assert(keys.length === values.length);
+        const map = createMap<T>();
+        for (let i = 0; i < keys.length; ++i) {
+            map.set(keys[i], values[i]);
+        }
+        return map;
+    }
+
     /**
      * Iterates through `array` by index and performs the callback on each element of array until the callback
      * returns a falsey value, then returns false.

src/compiler/diagnosticMessages.json

@@ -3203,9 +3203,16 @@
     },
     "Scoped package detected, looking in '{0}'": {
         "category": "Message",
-        "code": "6182"
+        "code": 6182
+    },
+    "Reusing resolution of module '{0}' to file '{1}' from old program.": {
+        "category": "Message",
+        "code": 6183
+    },
+    "Reusing module resolutions originating in '{0}' since resolutions are unchanged from old program.": {
+        "category": "Message",
+        "code": 6184
     },
-
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",
         "code": 7005

src/compiler/program.ts

@@ -2408,7 +2408,14 @@ namespace ts {
         /* @internal */ getResolvedTypeReferenceDirectives(): Map<ResolvedTypeReferenceDirective>;
         /* @internal */ isSourceFileFromExternalLibrary(file: SourceFile): boolean;
         // For testing purposes only.
-        /* @internal */ structureIsReused?: boolean;
+        /* @internal */ structureIsReused?: StructureIsReused;
+    }
+
+    /* @internal */
+    export const enum StructureIsReused {
+        Not         = 0,
+        SafeModules = 1 << 0,
+        Completely  = 1 << 1,
     }
 
     export interface CustomTransformers {

src/compiler/types.ts

@@ -122,9 +122,8 @@ namespace ts {
 
     /* @internal */
     export function hasChangesInResolutions<T>(names: string[], newResolutions: T[], oldResolutions: Map<T>, comparer: (oldResolution: T, newResolution: T) => boolean): boolean {
-        if (names.length !== newResolutions.length) {
-            return false;
-        }
+        Debug.assert(names.length === newResolutions.length);
+
         for (let i = 0; i < names.length; i++) {
             const newResolution = newResolutions[i];
             const oldResolution = oldResolutions && oldResolutions.get(names[i]);

src/compiler/utilities.ts

@@ -201,14 +201,13 @@ namespace ts {
             assert.isTrue(diags.length === 1, "one diagnostic expected");
             assert.isTrue(typeof diags[0].messageText === "string" && ((<string>diags[0].messageText).indexOf("Cannot find module") === 0), "should be 'cannot find module' message");
 
-            // assert that import will success once file appear on disk
             fileMap.set(imported.name, imported);
             fileExistsCalledForBar = false;
             rootScriptInfo.editContent(0, root.content.length, `import {y} from "bar"`);
 
             diags = project.getLanguageService().getSemanticDiagnostics(root.name);
-            assert.isTrue(fileExistsCalledForBar, "'fileExists' should be called");
-            assert.isTrue(diags.length === 0);
+            assert.isTrue(fileExistsCalledForBar, "'fileExists' should be called.");
+            assert.isTrue(diags.length === 0, "The import should succeed once the imported file appears on disk.");
         });
     });
 }

src/harness/unittests/cachingInServerLSHost.ts

@@ -1042,7 +1042,7 @@ import b = require("./moduleB");
             assert.equal(diagnostics1.length, 1, "expected one diagnostic");
 
             createProgram(names, {}, compilerHost, program1);
-            assert.isTrue(program1.structureIsReused);
+            assert.isTrue(program1.structureIsReused === StructureIsReused.Completely);
             const diagnostics2 = program1.getFileProcessingDiagnostics().getDiagnostics();
             assert.equal(diagnostics2.length, 1, "expected one diagnostic");
             assert.equal(diagnostics1[0].messageText, diagnostics2[0].messageText, "expected one diagnostic");

src/harness/unittests/moduleResolution.ts

@@ -552,7 +552,7 @@ namespace ts.server {
             // bump up the version if
             // - oldProgram is not set - this is a first time updateGraph is called
             // - newProgram is different from the old program and structure of the old program was not reused.
-            if (!oldProgram || (this.program !== oldProgram && !oldProgram.structureIsReused)) {
+            if (!oldProgram || (this.program !== oldProgram && !(oldProgram.structureIsReused & StructureIsReused.Completely))) {
                 hasChanges = true;
                 if (oldProgram) {
                     for (const f of oldProgram.getSourceFiles()) {