observability

1 files changed, 131 insertions, 0 deletions

diff --git a/packages/taler-wallet-core/src/observable-wrappers.ts b/packages/taler-wallet-core/src/observable-wrappers.ts
new file mode 100644
index 000000000..77839e047
--- /dev/null
+++ b/packages/taler-wallet-core/src/observable-wrappers.ts
@@ -0,0 +1,131 @@
+/*
+ This file is part of GNU Taler
+ (C) 2024 Taler Systems SA
+
+ GNU Taler is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
+
+ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+/**
+ * @fileoverview Wrappers/proxies to make various interfaces observable.
+ */
+
+/**
+ * Imports.
+ */
+import {
+  ObservabilityContext,
+  ObservabilityEventType,
+  RetryLoopOpts,
+  getErrorDetailFromException,
+} from "@gnu-taler/taler-util";
+import {
+  HttpRequestLibrary,
+  HttpRequestOptions,
+  HttpResponse,
+} from "@gnu-taler/taler-util/http";
+import { TaskIdStr } from "./common.js";
+import { TaskScheduler } from "./shepherd.js";
+
+/**
+ * Task scheduler with extra observability events.
+ */
+export class ObservableTaskScheduler implements TaskScheduler {
+  constructor(
+    private impl: TaskScheduler,
+    private oc: ObservabilityContext,
+  ) {}
+
+  private taskDepCache = new Set<string>();
+
+  private declareDep(taskId: TaskIdStr): void {
+    if (this.taskDepCache.size > 500) {
+      this.taskDepCache.clear();
+    }
+    if (!this.taskDepCache.has(taskId)) {
+      this.taskDepCache.add(taskId);
+      this.oc.observe({
+        type: ObservabilityEventType.TaskDependency,
+        taskId,
+      });
+    }
+  }
+
+  ensureRunning(): void {
+    return this.impl.ensureRunning();
+  }
+
+  run(opts?: RetryLoopOpts | undefined): Promise<void> {
+    return this.impl.run(opts);
+  }
+  startShepherdTask(taskId: TaskIdStr): void {
+    this.declareDep(taskId);
+    this.oc.observe({
+      type: ObservabilityEventType.StartTask,
+      taskId,
+    });
+    return this.impl.startShepherdTask(taskId);
+  }
+  stopShepherdTask(taskId: TaskIdStr): void {
+    this.declareDep(taskId);
+    this.oc.observe({
+      type: ObservabilityEventType.StopTask,
+      taskId,
+    });
+    return this.impl.stopShepherdTask(taskId);
+  }
+  resetTaskRetries(taskId: TaskIdStr): Promise<void> {
+    this.declareDep(taskId);
+    if (this.taskDepCache.size > 500) {
+      this.taskDepCache.clear();
+    }
+    this.oc.observe({
+      type: ObservabilityEventType.ResetTask,
+      taskId,
+    });
+    return this.impl.resetTaskRetries(taskId);
+  }
+  reload(): void {
+    return this.impl.reload();
+  }
+}
+
+export class ObservableHttpClientLibrary implements HttpRequestLibrary {
+  constructor(
+    private impl: HttpRequestLibrary,
+    private oc: ObservabilityContext,
+  ) {}
+  async fetch(
+    url: string,
+    opt?: HttpRequestOptions | undefined,
+  ): Promise<HttpResponse> {
+    this.oc.observe({
+      type: ObservabilityEventType.HttpFetchStart,
+      url: url,
+    });
+    try {
+      const res = await this.impl.fetch(url, opt);
+      this.oc.observe({
+        type: ObservabilityEventType.HttpFetchFinishSuccess,
+        url,
+        status: res.status,
+      });
+      return res;
+    } catch (e) {
+      this.oc.observe({
+        type: ObservabilityEventType.HttpFetchFinishError,
+        url,
+        error: getErrorDetailFromException(e),
+      });
+      throw e;
+    }
+  }
+}