Teach EmbeddedWorkerInstance to create a process when it needs one.

content/browser/service_worker/embedded_worker_instance.h

 // Copyright 2013 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 CONTENT_BROWSER_SERVICE_WORKER_EMBEDDED_WORKER_INSTANCE_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_EMBEDDED_WORKER_INSTANCE_H_
 
 #include <map>
+#include <vector>
 
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
 #include "base/gtest_prod_util.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "base/observer_list.h"
 #include "base/strings/string16.h"
 #include "content/common/content_export.h"
 #include "content/common/service_worker/service_worker_status_code.h"
 
 class GURL;
 
 namespace IPC {
 class Message;
 }
 
 namespace content {
 
 class EmbeddedWorkerRegistry;
 struct ServiceWorkerFetchRequest;
 
 // This gives an interface to control one EmbeddedWorker instance, which
 // may be 'in-waiting' or running in one of the child processes added by
 // AddProcessReference().
 class CONTENT_EXPORT EmbeddedWorkerInstance {
  public:
+  typedef base::Callback<void(ServiceWorkerStatusCode)> StatusCallback;
   enum Status {
     STOPPED,
     STARTING,
     RUNNING,
     STOPPING,
   };
 
   class Listener {
    public:
     virtual ~Listener() {}
     virtual void OnStarted() = 0;
     virtual void OnStopped() = 0;
     virtual void OnReportException(const base::string16& error_message,
                                    int line_number,
                                    int column_number,
                                    const GURL& source_url) {}
     virtual void OnReportConsoleMessage(int source_identifier,
                                         int message_level,
                                         const base::string16& message,
                                         int line_number,
                                         const GURL& source_url) {}
     // These should return false if the message is not handled by this
     // listener. (TODO(kinuko): consider using IPC::Listener interface)
     // TODO(kinuko): Deprecate OnReplyReceived.
     virtual bool OnMessageReceived(const IPC::Message& message) = 0;
   };
 
   ~EmbeddedWorkerInstance();
 
-  // Starts the worker. It is invalid to call this when the worker is
-  // not in STOPPED status.
-  ServiceWorkerStatusCode Start(int64 service_worker_version_id,
-                                const GURL& scope,
-                                const GURL& script_url);
+  // Starts the worker. It is invalid to call this when the worker is not in
+  // STOPPED status. |callback| is invoked when the worker's process is created
+  // if necessary and the IPC to evaluate the worker's script is sent.
+  // Observer::OnStarted() is run when the worker is actually started.
+  void Start(int64 service_worker_version_id,
+             const GURL& scope,
+             const GURL& script_url,
+             const std::vector<int>& possible_process_ids,
+             const StatusCallback& callback);
 
   // Stops the worker. It is invalid to call this when the worker is
   // not in STARTING or RUNNING status.
   // This returns false if stopping a worker fails immediately, e.g. when
   // IPC couldn't be sent to the worker.
   ServiceWorkerStatusCode Stop();
 
   // Sends |message| to the embedded worker running in the child process.
   // It is invalid to call this while the worker is not in RUNNING status.
   ServiceWorkerStatusCode SendMessage(const IPC::Message& message);
@@ skipping 18 matching lines @@
   friend class EmbeddedWorkerRegistry;
   FRIEND_TEST_ALL_PREFIXES(EmbeddedWorkerInstanceTest, StartAndStop);
 
   typedef std::map<int, int> ProcessRefMap;
 
   // Constructor is called via EmbeddedWorkerRegistry::CreateWorker().
   // This instance holds a ref of |registry|.
   EmbeddedWorkerInstance(EmbeddedWorkerRegistry* registry,
                          int embedded_worker_id);
 
+  // Called back from EmbeddedWorkerRegistry after Start() passes control to the
+  // UI thread to acquire a reference to the process.
+  void RecordProcessId(int process_id, ServiceWorkerStatusCode status);
+
   // Called back from Registry when the worker instance has ack'ed that
   // its WorkerGlobalScope is actually started on |thread_id| in the
   // child process.
   // This will change the internal status from STARTING to RUNNING.
   void OnStarted(int thread_id);
 
   // Called back from Registry when the worker instance has ack'ed that
   // its WorkerGlobalScope is actually stopped in the child process.
   // This will change the internal status from STARTING or RUNNING to
   // STOPPED.
@@ skipping 10 matching lines @@
                          int column_number,
                          const GURL& source_url);
 
   // Called back from Registry when the worker instance reports to the console.
   void OnReportConsoleMessage(int source_identifier,
                               int message_level,
                               const base::string16& message,
                               int line_number,
                               const GURL& source_url);
 
-  // Chooses a process to start this worker and populate process_id_.
-  // Returns false when no process is available.
-  bool ChooseProcess();
+  // Chooses a list of processes to try to start this worker in, ordered by how
+  // many clients are currently in those processes.
+  std::vector<int> SortProcesses(
+      const std::vector<int>& possible_process_ids) const;
 
   scoped_refptr<EmbeddedWorkerRegistry> registry_;
   const int embedded_worker_id_;
   Status status_;
 
   // Current running information. -1 indicates the worker is not running.
   int process_id_;
   int thread_id_;
 
   ProcessRefMap process_refs_;
   ListenerList listener_list_;
 
   DISALLOW_COPY_AND_ASSIGN(EmbeddedWorkerInstance);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_EMBEDDED_WORKER_INSTANCE_H_