perf(lsp): Only evict caches on JS side when things actually change (#23293)

Currently we evict a lot of the caches on the JS side of things on every
request, namely script versions, script file names, and compiler
settings (as of #23283, it's not quite every request but it's still
unnecessarily often).

This PR reports changes to the JS side, so that it can evict exactly the
caches that it needs too. We might want to do some batching in the
future so as not to do 1 request per change.

1 files changed, 46 insertions, 23 deletions

diff --git a/cli/tsc/99_main_compiler.js b/cli/tsc/99_main_compiler.js
index ef1077af8..ea70343be 100644
--- a/cli/tsc/99_main_compiler.js
+++ b/cli/tsc/99_main_compiler.js
@@ -164,16 +164,15 @@ delete Object.prototype.__proto__;
 
   /** @type {ts.CompilerOptions | null} */
   let tsConfigCache = null;
-  /** @type {string | null} */
-  let tsConfigCacheProjectVersion = null;
 
   /** @type {string | null} */
   let projectVersionCache = null;
-  /** @type {number | null} */
-  let projectVersionCacheLastRequestId = null;
 
-  /** @type {number | null} */
-  let lastRequestId = null;
+  const ChangeKind = {
+    Opened: 0,
+    Modified: 1,
+    Closed: 2,
+  };
 
   /**
    * @param {ts.CompilerOptions | ts.MinimalResolutionCacheHost} settingsOrHost
@@ -545,13 +544,14 @@ delete Object.prototype.__proto__;
     },
     getProjectVersion() {
       if (
-        projectVersionCache && projectVersionCacheLastRequestId == lastRequestId
+        projectVersionCache
       ) {
+        debug(`getProjectVersion cache hit : ${projectVersionCache}`);
         return projectVersionCache;
       }
       const projectVersion = ops.op_project_version();
       projectVersionCache = projectVersion;
-      projectVersionCacheLastRequestId = lastRequestId;
+      debug(`getProjectVersion cache miss : ${projectVersionCache}`);
       return projectVersion;
     },
     // @ts-ignore Undocumented method.
@@ -751,8 +751,7 @@ delete Object.prototype.__proto__;
       if (logDebug) {
         debug("host.getCompilationSettings()");
       }
-      const projectVersion = this.getProjectVersion();
-      if (tsConfigCache && tsConfigCacheProjectVersion == projectVersion) {
+      if (tsConfigCache) {
         return tsConfigCache;
       }
       const tsConfig = normalizeConfig(ops.op_ts_config());
@@ -766,7 +765,6 @@ delete Object.prototype.__proto__;
         debug(ts.formatDiagnostics(errors, host));
       }
       tsConfigCache = options;
-      tsConfigCacheProjectVersion = projectVersion;
       return options;
     },
     getScriptFileNames() {
@@ -801,13 +799,6 @@ delete Object.prototype.__proto__;
         debug(`host.getScriptSnapshot("${specifier}")`);
       }
       let sourceFile = sourceFileCache.get(specifier);
-      if (
-        !specifier.startsWith(ASSETS_URL_PREFIX) &&
-        sourceFile?.version != this.getScriptVersion(specifier)
-      ) {
-        sourceFileCache.delete(specifier);
-        sourceFile = undefined;
-      }
       if (!sourceFile) {
         sourceFile = this.getSourceFile(
           specifier,
@@ -1047,12 +1038,36 @@ delete Object.prototype.__proto__;
     if (logDebug) {
       debug(`serverRequest()`, id, method, args);
     }
-    lastRequestId = id;
-    // reset all memoized source files names
-    scriptFileNamesCache = undefined;
-    // evict all memoized source file versions
-    scriptVersionCache.clear();
     switch (method) {
+      case "$projectChanged": {
+        /** @type {[string, number][]} */
+        const changedScripts = args[0];
+        /** @type {string} */
+        const newProjectVersion = args[1];
+        /** @type {boolean} */
+        const configChanged = args[2];
+
+        if (configChanged) {
+          tsConfigCache = null;
+        }
+
+        projectVersionCache = newProjectVersion;
+
+        let opened = false;
+        for (const { 0: script, 1: changeKind } of changedScripts) {
+          if (changeKind == ChangeKind.Opened) {
+            opened = true;
+          }
+          scriptVersionCache.delete(script);
+          sourceFileCache.delete(script);
+        }
+
+        if (configChanged || opened) {
+          scriptFileNamesCache = undefined;
+        }
+
+        return respond(id);
+      }
       case "$restart": {
         serverRestart();
         return respond(id, true);
@@ -1067,6 +1082,14 @@ delete Object.prototype.__proto__;
         return respond(id, getAssets());
       }
       case "$getDiagnostics": {
+        const projectVersion = args[1];
+        // there's a possibility that we receive a change notification
+        // but the diagnostic server queues a `$getDiagnostics` request
+        // with a stale project version. in that case, treat it as cancelled
+        // (it's about to be invalidated anyway).
+        if (projectVersionCache && projectVersion !== projectVersionCache) {
+          return respond(id, {});
+        }
         try {
           /** @type {Record<string, any[]>} */
           const diagnosticMap = {};