Put CachedOperation in helpers.

Author: jcreedcmu

extensions/ql-vscode/src/definitions.ts

@@ -7,6 +7,7 @@ import { EntityValue, getResultSetSchema, LineColumnLocation, UrlValue, ColumnKi
 import { CodeQLCliServer } from "./cli";
 import { DatabaseItem, DatabaseManager } from "./databases";
 import * as helpers from './helpers';
+import { CachedOperation } from './helpers';
 import * as messages from "./messages";
 import { QueryServerClient } from "./queryserver-client";
 import { compileAndRunQueryAgainstDatabase, QueryWithResults } from "./run-queries";
@@ -196,58 +197,3 @@ function fileRangeFromURI(uri: UrlValue, db: DatabaseItem): FileRange | undefine
     }
   }
 }
-
-const CACHE_SIZE = 100;
-class CachedOperation<U> {
-  private readonly operation: (t: string) => Promise<U>;
-  private readonly cached: Map<string, U>;
-  private readonly lru: string[];
-  private readonly inProgressCallbacks: Map<string, [(u: U) => void, (reason?: any) => void][]>;
-
-  constructor(operation: (t: string) => Promise<U>) {
-    this.operation = operation;
-    this.lru = [];
-    this.inProgressCallbacks = new Map<string, [(u: U) => void, (reason?: any) => void][]>();
-    this.cached = new Map<string, U>();
-  }
-
-  async get(t: string): Promise<U> {
-    // Try and retrieve from the cache
-    const fromCache = this.cached.get(t);
-    if (fromCache !== undefined) {
-      // Move to end of lru list
-      this.lru.push(this.lru.splice(this.lru.findIndex(v => v === t), 1)[0])
-      return fromCache;
-    }
-    // Otherwise check if in progress
-    const inProgressCallback = this.inProgressCallbacks.get(t);
-    if (inProgressCallback !== undefined) {
-      // If so wait for it to resolve
-      return await new Promise((resolve, reject) => {
-        inProgressCallback.push([resolve, reject]);
-      });
-    }
-
-    // Otherwise compute the new value, but leave a callback to allow sharing work
-    const callbacks: [(u: U) => void, (reason?: any) => void][] = [];
-    this.inProgressCallbacks.set(t, callbacks);
-    try {
-      const result = await this.operation(t);
-      callbacks.forEach(f => f[0](result));
-      this.inProgressCallbacks.delete(t);
-      if (this.lru.length > CACHE_SIZE) {
-        const toRemove = this.lru.shift()!;
-        this.cached.delete(toRemove);
-      }
-      this.lru.push(t);
-      this.cached.set(t, result);
-      return result;
-    } catch (e) {
-      // Rethrow error on all callbacks
-      callbacks.forEach(f => f[1](e));
-      throw e;
-    } finally {
-      this.inProgressCallbacks.delete(t);
-    }
-  }
-}

extensions/ql-vscode/src/helpers.ts

@@ -298,3 +298,60 @@ export async function resolveDatasetFolder(cliServer: CodeQLCliServer, datasetFo
   const qlpack = await getQlPackForDbscheme(cliServer, dbscheme);
   return { dbscheme, qlpack };
 }
+
+/**
+ * A cached mapping from strings to value of type U.
+ */
+export class CachedOperation<U> {
+  private readonly operation: (t: string) => Promise<U>;
+  private readonly cached: Map<string, U>;
+  private readonly lru: string[];
+  private readonly inProgressCallbacks: Map<string, [(u: U) => void, (reason?: any) => void][]>;
+
+  constructor(operation: (t: string) => Promise<U>, private cacheSize = 100) {
+    this.operation = operation;
+    this.lru = [];
+    this.inProgressCallbacks = new Map<string, [(u: U) => void, (reason?: any) => void][]>();
+    this.cached = new Map<string, U>();
+  }
+
+  async get(t: string): Promise<U> {
+    // Try and retrieve from the cache
+    const fromCache = this.cached.get(t);
+    if (fromCache !== undefined) {
+      // Move to end of lru list
+      this.lru.push(this.lru.splice(this.lru.findIndex(v => v === t), 1)[0])
+      return fromCache;
+    }
+    // Otherwise check if in progress
+    const inProgressCallback = this.inProgressCallbacks.get(t);
+    if (inProgressCallback !== undefined) {
+      // If so wait for it to resolve
+      return await new Promise((resolve, reject) => {
+        inProgressCallback.push([resolve, reject]);
+      });
+    }
+
+    // Otherwise compute the new value, but leave a callback to allow sharing work
+    const callbacks: [(u: U) => void, (reason?: any) => void][] = [];
+    this.inProgressCallbacks.set(t, callbacks);
+    try {
+      const result = await this.operation(t);
+      callbacks.forEach(f => f[0](result));
+      this.inProgressCallbacks.delete(t);
+      if (this.lru.length > this.cacheSize) {
+        const toRemove = this.lru.shift()!;
+        this.cached.delete(toRemove);
+      }
+      this.lru.push(t);
+      this.cached.set(t, result);
+      return result;
+    } catch (e) {
+      // Rethrow error on all callbacks
+      callbacks.forEach(f => f[1](e));
+      throw e;
+    } finally {
+      this.inProgressCallbacks.delete(t);
+    }
+  }
+}