Remove refCount from resolutions as we dont need it explicitly since its tracked by files it references (#59041)

Author: sheetalkamat

src/compiler/resolutionCache.ts

@@ -169,7 +169,6 @@ export interface ResolutionWithFailedLookupLocations {
     failedLookupLocations?: string[];
     affectingLocations?: string[];
     isInvalidated?: boolean;
-    refCount?: number;
     // Files that have this resolution using
     files?: Set<Path>;
     alternateResult?: string;
@@ -1095,28 +1094,21 @@ export function createResolutionCache(resolutionHost: ResolutionCacheHost, rootD
         getResolutionWithResolvedFileName: GetResolutionWithResolvedFileName<T, R>,
         deferWatchingNonRelativeResolution: boolean,
     ) {
-        if (resolution.refCount) {
-            resolution.refCount++;
-            Debug.assertIsDefined(resolution.files);
+        (resolution.files ??= new Set()).add(filePath);
+        if (resolution.files.size !== 1) return;
+        if (!deferWatchingNonRelativeResolution || isExternalModuleNameRelative(name)) {
+            watchFailedLookupLocationOfResolution(resolution);
         }
         else {
-            resolution.refCount = 1;
-            Debug.assert(!resolution.files?.size); // This resolution shouldnt be referenced by any file yet
-            if (!deferWatchingNonRelativeResolution || isExternalModuleNameRelative(name)) {
-                watchFailedLookupLocationOfResolution(resolution);
-            }
-            else {
-                nonRelativeExternalModuleResolutions.add(name, resolution);
-            }
-            const resolved = getResolutionWithResolvedFileName(resolution);
-            if (resolved && resolved.resolvedFileName) {
-                const key = resolutionHost.toPath(resolved.resolvedFileName);
-                let resolutions = resolvedFileToResolution.get(key);
-                if (!resolutions) resolvedFileToResolution.set(key, resolutions = new Set());
-                resolutions.add(resolution);
-            }
+            nonRelativeExternalModuleResolutions.add(name, resolution);
+        }
+        const resolved = getResolutionWithResolvedFileName(resolution);
+        if (resolved && resolved.resolvedFileName) {
+            const key = resolutionHost.toPath(resolved.resolvedFileName);
+            let resolutions = resolvedFileToResolution.get(key);
+            if (!resolutions) resolvedFileToResolution.set(key, resolutions = new Set());
+            resolutions.add(resolution);
         }
-        (resolution.files ??= new Set()).add(filePath);
     }
 
     function watchFailedLookupLocation(failedLookupLocation: string, setAtRoot: boolean) {
@@ -1144,7 +1136,7 @@ export function createResolutionCache(resolutionHost: ResolutionCacheHost, rootD
     }
 
     function watchFailedLookupLocationOfResolution(resolution: ResolutionWithFailedLookupLocations) {
-        Debug.assert(!!resolution.refCount);
+        Debug.assert(!!resolution.files?.size);
 
         const { failedLookupLocations, affectingLocations, alternateResult } = resolution;
         if (!failedLookupLocations?.length && !affectingLocations?.length && !alternateResult) return;
@@ -1165,7 +1157,7 @@ export function createResolutionCache(resolutionHost: ResolutionCacheHost, rootD
     }
 
     function watchAffectingLocationsOfResolution(resolution: ResolutionWithFailedLookupLocations, addToResolutionsWithOnlyAffectingLocations: boolean) {
-        Debug.assert(!!resolution.refCount);
+        Debug.assert(!!resolution.files?.size);
         const { affectingLocations } = resolution;
         if (!affectingLocations?.length) return;
         if (addToResolutionsWithOnlyAffectingLocations) resolutionsWithOnlyAffectingLocations.add(resolution);
@@ -1381,10 +1373,8 @@ export function createResolutionCache(resolutionHost: ResolutionCacheHost, rootD
         syncDirWatcherRemove?: boolean,
     ) {
         Debug.checkDefined(resolution.files).delete(filePath);
-        resolution.refCount!--;
-        if (resolution.refCount) {
-            return;
-        }
+        if (resolution.files!.size) return;
+        resolution.files = undefined;
         const resolved = getResolutionWithResolvedFileName(resolution);
         if (resolved && resolved.resolvedFileName) {
             const key = resolutionHost.toPath(resolved.resolvedFileName);

src/harness/incrementalUtils.ts

@@ -254,15 +254,11 @@ export function verifyResolutionCache(
     // Verify ref count
     resolutionToRefs.forEach((info, resolution) => {
         ts.Debug.assert(
-            resolution.refCount === info.length,
-            `${projectName}:: Expected Resolution ref count ${info.length} but got ${resolution.refCount}`,
+            resolution.files?.size === info.length,
+            `${projectName}:: Expected Resolution ref count ${info.length} but got ${resolution.files?.size}`,
             () =>
                 `Expected from:: ${JSON.stringify(info, undefined, " ")}` +
-                `Actual from: ${resolution.refCount}`,
-        );
-        ts.Debug.assert(
-            resolutionToExpected.get(resolution)!.refCount === resolution.refCount,
-            `${projectName}:: Expected Resolution ref count ${resolutionToExpected.get(resolution)!.refCount} but got ${resolution.refCount}`,
+                `Actual from: ${resolution.files?.size}`,
         );
         verifySet(resolutionToExpected.get(resolution)!.files, resolution.files, `${projectName}:: Resolution files`);
     });
@@ -280,10 +276,9 @@ export function verifyResolutionCache(
     actual.resolvedTypeReferenceDirectives.forEach((_resolutions, path) => expected.removeResolutionsOfFile(path));
     expected.finishCachingPerDirectoryResolution(/*newProgram*/ undefined, actualProgram);
 
-    resolutionToExpected.forEach(expected => {
-        ts.Debug.assert(!expected.refCount, `${projectName}:: All the resolution should be released`);
-        ts.Debug.assert(!expected.files?.size, `${projectName}:: Shouldnt ref to any files`);
-    });
+    resolutionToExpected.forEach(
+        expected => ts.Debug.assert(!expected.files?.size, `${projectName}:: Shouldnt ref to any files`),
+    );
     ts.Debug.assert(expected.resolvedFileToResolution.size === 0, `${projectName}:: resolvedFileToResolution should be released`);
     ts.Debug.assert(expected.resolutionsWithFailedLookups.size === 0, `${projectName}:: resolutionsWithFailedLookups should be released`);
     ts.Debug.assert(expected.resolutionsWithOnlyAffectingLocations.size === 0, `${projectName}:: resolutionsWithOnlyAffectingLocations should be released`);