extensions/browser/service_worker_task_queue.h

// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef EXTENSIONS_BROWSER_SERVICE_WORKER_TASK_QUEUE_H_
#define EXTENSIONS_BROWSER_SERVICE_WORKER_TASK_QUEUE_H_

#include <map>
#include <set>
#include <unordered_map>
#include <vector>

#include "base/memory/weak_ptr.h"
#include "base/strings/string_util.h"
#include "base/version.h"
#include "components/keyed_service/core/keyed_service.h"
#include "extensions/browser/lazy_context_id.h"
#include "extensions/browser/lazy_context_task_queue.h"
#include "extensions/browser/service_worker/worker_id.h"
#include "extensions/common/activation_sequence.h"
#include "extensions/common/extension_id.h"
#include "url/gurl.h"

namespace content {
class BrowserContext;
class ServiceWorkerContext;
}

namespace extensions {
class Extension;

// A service worker based background specific LazyContextTaskQueue.
//
// This class queues up and runs tasks added through AddPendingTask, after
// registering and starting extension's background Service Worker script if
// necessary.
//
// There are two sets of concepts/events that are important to this class:
//
// C1) Registering and starting a background worker:
//   Upon extension activation, this class registers the extension's
//   background worker if necessary. After that, if it has queued up tasks
//   in |pending_tasks_|, then it moves on to starting the worker. Registration
//   and start are initiated from this class. Once started, the worker is
//   considered browser process ready. These workers are stored in
//   |worker_state_map_| with |browser_ready| = false until we run tasks.
//
// C2) Listening for worker's state update from the renderer:
//   - Init (DidInitializeServiceWorkerContext) when the worker is initialized,
//       JavaScript starts running after this.
//   - Start (DidStartServiceWorkerContext) when the worker has reached
//       loadstop. The worker is considered ready to run tasks from this task
//       queue. The worker's entry in |worker_state_map_| will carry
//       |renderer_ready| = true.
//   - Stop (DidStopServiceWorkerContext) when the worker is destroyed, we clear
//       its |renderer_ready| status from |worker_state_map_|.
//
// Once a worker reaches readiness in both browser process
// (DidStartWorkerForScope) and worker process (DidStartServiceWorkerContext),
// we consider the worker to be ready to run tasks from |pending_tasks_|.
// Note that events from #C1 and #C2 are somewhat independent, e.g. it is
// possible to see an Init state update from #C2 before #C1 has seen a start
// worker completion.
//
// Sequences of extension activation:
//   This class also assigns a unique sequence id to an extension activation so
//   that it can differentiate between two activations of a particular extension
//   (e.g. reloading an extension can cause two activations). |pending_tasks_|,
//   worker registration and start (#C1) have sequence ids attached to them.
//   The sequence is expired upon extension deactivation, and tasks are dropped
//   from |pending_tasks_|.
//
// TODO(lazyboy): Clean up queue when extension is unloaded/uninstalled.
class ServiceWorkerTaskQueue : public KeyedService,
                               public LazyContextTaskQueue {
 public:
  explicit ServiceWorkerTaskQueue(content::BrowserContext* browser_context);
  ~ServiceWorkerTaskQueue() override;

  // Convenience method to return the ServiceWorkerTaskQueue for a given
  // |context|.
  static ServiceWorkerTaskQueue* Get(content::BrowserContext* context);

  bool ShouldEnqueueTask(content::BrowserContext* context,
                         const Extension* extension) override;
  void AddPendingTask(const LazyContextId& context_id,
                      PendingTask task) override;

  // Performs Service Worker related tasks upon |extension| activation,
  // e.g. registering |extension|'s worker, executing any pending tasks.
  void ActivateExtension(const Extension* extension);
  // Performs Service Worker related tasks upon |extension| deactivation,
  // e.g. unregistering |extension|'s worker.
  void DeactivateExtension(const Extension* extension);

  // Called once an extension Service Worker context was initialized but not
  // necessarily started executing its JavaScript.
  void DidInitializeServiceWorkerContext(int render_process_id,
                                         const ExtensionId& extension_id,
                                         int64_t service_worker_version_id,
                                         int thread_id);
  // Called once an extension Service Worker started running.
  // This can be thought as "loadstop", i.e. the global JS script of the worker
  // has completed executing.
  void DidStartServiceWorkerContext(int render_process_id,
                                    const ExtensionId& extension_id,
                                    ActivationSequence activation_sequence,
                                    const GURL& service_worker_scope,
                                    int64_t service_worker_version_id,
                                    int thread_id);
  // Called once an extension Service Worker was destroyed.
  void DidStopServiceWorkerContext(int render_process_id,
                                   const ExtensionId& extension_id,
                                   ActivationSequence activation_sequence,
                                   const GURL& service_worker_scope,
                                   int64_t service_worker_version_id,
                                   int thread_id);

  // Returns the current ActivationSequence for an extension, if the extension
  // is currently activated. Returns base::nullopt if the extension isn't
  // activated.
  base::Optional<ActivationSequence> GetCurrentSequence(
      const ExtensionId& extension_id) const;

  class TestObserver {
   public:
    TestObserver();
    virtual ~TestObserver();

    // Called when an extension with id |extension_id| is going to be activated.
    // |will_register_service_worker| is true if a Service Worker will be
    // registered.
    virtual void OnActivateExtension(const ExtensionId& extension_id,
                                     bool will_register_service_worker) {}
    virtual void DidStartWorkerFail(const ExtensionId& extension_id,
                                    size_t num_pending_tasks) {}

   private:
    DISALLOW_COPY_AND_ASSIGN(TestObserver);
  };

  static void SetObserverForTest(TestObserver* observer);

  size_t GetNumPendingTasksForTest(const LazyContextId& lazy_context_id);

 private:
  using SequencedContextId = std::pair<LazyContextId, ActivationSequence>;

  class WorkerState;

  static void DidStartWorkerForScopeOnCoreThread(
      const SequencedContextId& context_id,
      base::WeakPtr<ServiceWorkerTaskQueue> task_queue,
      int64_t version_id,
      int process_id,
      int thread_id);
  static void DidStartWorkerFailOnCoreThread(
      const SequencedContextId& context_id,
      base::WeakPtr<ServiceWorkerTaskQueue> task_queue);
  static void StartServiceWorkerOnCoreThreadToRunTasks(
      base::WeakPtr<ServiceWorkerTaskQueue> task_queue_weak,
      const SequencedContextId& context_id,
      content::ServiceWorkerContext* service_worker_context);

  void RunTasksAfterStartWorker(const SequencedContextId& context_id);

  void DidRegisterServiceWorker(const SequencedContextId& context_id,
                                bool success);
  void DidUnregisterServiceWorker(const ExtensionId& extension_id,
                                  ActivationSequence sequence,
                                  bool success);

  void DidStartWorkerForScope(const SequencedContextId& context_id,
                              int64_t version_id,
                              int process_id,
                              int thread_id);
  void DidStartWorkerFail(const SequencedContextId& context_id);

  // The following three methods retrieve, store, and remove information
  // about Service Worker registration of SW based background pages:
  //
  // Retrieves the last version of the extension, returns invalid version if
  // there isn't any such extension.
  base::Version RetrieveRegisteredServiceWorkerVersion(
      const ExtensionId& extension_id);
  // Records that the extension with |extension_id| and |version| successfully
  // registered a Service Worker.
  void SetRegisteredServiceWorkerInfo(const ExtensionId& extension_id,
                                      const base::Version& version);
  // Clears any record of registered Service Worker for the given extension with
  // |extension_id|.
  void RemoveRegisteredServiceWorkerInfo(const ExtensionId& extension_id);

  // If the worker with |context_id| has seen worker start
  // (DidStartWorkerForScope) and load (DidStartServiceWorkerContext) then runs
  // all pending tasks for that worker.
  void RunPendingTasksIfWorkerReady(const SequencedContextId& context_id);

  // Returns true if |sequence| is the current activation sequence for
  // |extension_id|.
  bool IsCurrentSequence(const ExtensionId& extension_id,
                         ActivationSequence sequence) const;

  WorkerState* GetWorkerState(const SequencedContextId& context_id);

  int next_activation_sequence_ = 0;

  // The state of worker of each activated extension.
  std::map<SequencedContextId, WorkerState> worker_state_map_;

  content::BrowserContext* const browser_context_ = nullptr;

  // A map of Service Worker registrations if this instance is for an
  // off-the-record BrowserContext. These are stored in the ExtensionPrefs
  // for a regular profile.
  // TODO(crbug.com/939664): Make this better by passing in something that
  // will manage storing and retrieving this data.
  std::unordered_map<ExtensionId, base::Version> off_the_record_registrations_;

  // Current ActivationSequence for each activated extensions.
  std::map<ExtensionId, ActivationSequence> activation_sequences_;

  base::WeakPtrFactory<ServiceWorkerTaskQueue> weak_factory_{this};

  DISALLOW_COPY_AND_ASSIGN(ServiceWorkerTaskQueue);
};

}  // namespace extensions

#endif  // EXTENSIONS_BROWSER_SERVICE_WORKER_TASK_QUEUE_H_