Make syntax tree typing deeply readonly and reuse them in language server

.vscode/launch.json

@@ -119,8 +119,18 @@
       "request": "launch",
       "args": ["--extensionDevelopmentPath=${workspaceFolder}/packages/cadl-vscode"],
       "env": {
-        "CADL_DEVELOPMENT_MODE": "true",
-        "CADL_SERVER_NODE_OPTIONS": "--nolazy --inspect-brk=4242"
+        // Log elapsed time for each call to server.
+        //"CADL_SERVER_LOG_TIMING": "true",
+
+        // Save .cpuprofile for last run of each server function here
+        // NOTE: This will add a lot of lag so don't trust logged timing if also enabled above.
+        //"CADL_SERVER_PROFILE_DIR": "${workspaceRoot}/temp",
+
+        // Use empty node options and don't debug while profiling to get the most accurate timing
+        //"CADL_SERVER_NODE_OPTIONS": "",
+
+        "CADL_SERVER_NODE_OPTIONS": "--nolazy --inspect-brk=4242",
+        "CADL_DEVELOPMENT_MODE": "true"
       },
       "presentation": {
         "hidden": true

common/changes/@cadl-lang/compiler/reuse-parse-and-bind_2022-08-22-18-59.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@cadl-lang/compiler",
+      "comment": "Perf: Reuse unchanged files and programs in language server.",
+      "type": "minor"
+    }
+  ],
+  "packageName": "@cadl-lang/compiler"
+}

common/changes/@cadl-lang/versioning/reuse-parse-and-bind_2022-08-22-18-59.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@cadl-lang/versioning",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@cadl-lang/versioning"
+}

common/changes/cadl-vscode/reuse-parse-and-bind_2022-08-22-18-59.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "cadl-vscode",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "cadl-vscode"
+}

packages/cadl-vscode/src/extension.ts

@@ -79,7 +79,7 @@ async function resolveCadlServer(context: ExtensionContext): Promise<Executable>
     const script = context.asAbsolutePath("../compiler/dist/server/server.js");
     // we use CLI instead of NODE_OPTIONS environment variable in this case
     // because --nolazy is not supported by NODE_OPTIONS.
-    const options = nodeOptions?.split(" ") ?? [];
+    const options = nodeOptions?.split(" ").filter((o) => o) ?? [];
     return { command: "node", args: [...options, script, ...args] };
   }
 

packages/compiler/config/config-loader.ts

@@ -1,14 +1,14 @@
 import jsyaml from "js-yaml";
 import { getDirectoryPath, joinPaths, resolvePath } from "../core/path-utils.js";
-import { SchemaValidator } from "../core/schema-validator.js";
+import { createJSONSchemaValidator } from "../core/schema-validator.js";
 import { CompilerHost, Diagnostic } from "../core/types.js";
 import { deepClone, deepFreeze, doIO, loadFile } from "../core/util.js";
 import { CadlConfigJsonSchema } from "./config-schema.js";
 import { CadlConfig } from "./types.js";
 
 export const CadlConfigFilename = "cadl-project.yaml";
 
-const defaultConfig: CadlConfig = deepFreeze({
+export const defaultConfig: CadlConfig = deepFreeze({
   diagnostics: [],
   emitters: {},
 });
@@ -88,7 +88,7 @@ export async function loadCadlConfigFile(
   };
 }
 
-const configValidator = new SchemaValidator(CadlConfigJsonSchema);
+const configValidator = createJSONSchemaValidator(CadlConfigJsonSchema);
 
 async function loadConfigFile(
   host: CompilerHost,