Support for multiple sync ModelSafeWorkers....

chrome/browser/sync/sessions/sync_session.h

 // Copyright (c) 2009 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.
 
 // A class representing an attempt to synchronize the local syncable data
 // store with a sync server. A SyncSession instance is passed as a stateful
 // bundle to and from various SyncerCommands with the goal of converging the
 // client view of data with that of the server. The commands twiddle with
 // session status in response to events and hiccups along the way, set and
 // query session progress with regards to conflict resolution and applying
 // server updates, and access the SyncSessionContext for the current session
 // via SyncSession instances.
 
 #ifndef CHROME_BROWSER_SYNC_SESSIONS_SYNC_SESSION_H_
 #define CHROME_BROWSER_SYNC_SESSIONS_SYNC_SESSION_H_
 
 #include <string>
+#include <vector>
 
 #include "base/basictypes.h"
 #include "base/scoped_ptr.h"
 #include "base/time.h"
 #include "chrome/browser/sync/sessions/session_state.h"
 #include "chrome/browser/sync/sessions/status_controller.h"
 #include "chrome/browser/sync/sessions/sync_session_context.h"
 #include "chrome/browser/sync/util/extensions_activity_monitor.h"
 
 namespace syncable {
 class WriteTransaction;
 }
 
 namespace browser_sync {
+class ModelSafeWorker;
+
 namespace sessions {
 
 class SyncSession {
  public:
   // The Delegate services events that occur during the session requiring an
   // explicit (and session-global) action, as opposed to events that are simply
   // recorded in per-session state.
   class Delegate {
    public:
     // The client was throttled and should cease-and-desist syncing activity
@@ skipping 50 matching lines @@
   void clear_auth_failure_occurred() { auth_failure_occurred_ = false; }
 
   // Volatile reader for the source member of the sync session object.  The
   // value is set to the SYNC_CYCLE_CONTINUATION value to signal that it has
   // been read.
   sync_pb::GetUpdatesCallerInfo::GetUpdatesSource TestAndSetSource();
   void set_source(sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source) {
     source_ = source;
   }
 
+  const std::vector<ModelSafeWorker*>& workers() const { return workers_; }
+
  private:
   // Extend the encapsulation boundary to utilities for internal member
   // assignments. This way, the scope of these actions is explicit, they can't
   // be overridden, and assigning is always accompanied by unassigning.
   friend class ScopedSetSessionWriteTransaction;
+  friend class ScopedModelSafeGroupRestriction;
 
   // The context for this session, guaranteed to outlive |this|.
   SyncSessionContext* const context_;
 
   // The source for initiating this sync session.
   sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source_;
 
   // Information about extensions activity since the last successful commit.
   ExtensionsActivityMonitor::Records extensions_activity_;
 
   // Used to allow various steps to share a transaction. Can be NULL.
   syncable::WriteTransaction* write_transaction_;
 
   // The delegate for this session, must never be NULL.
   Delegate* delegate_;
 
   // Our controller for various status and error counters.
   StatusController status_controller_;
 
   // Used to determine if an auth error notification should be sent out.
   bool auth_failure_occurred_;
 
+  // The set of active ModelSafeWorkers for the duration of this session.
+  const std::vector<ModelSafeWorker*> workers_;
+
+  // Used to fail read/write operations on this SyncSession that don't obey the
+  // currently active ModelSafeWorker contract.
+  bool group_restriction_in_effect_;
+  ModelSafeGroup group_restriction_;
+
   DISALLOW_COPY_AND_ASSIGN(SyncSession);
 };
 
 // Installs a WriteTransaction to a given session and later clears it when the
 // utility falls out of scope. Transactions are not nestable, so it is an error
 // to try and use one of these if the session already has a transaction.
 class ScopedSetSessionWriteTransaction {
  public:
   ScopedSetSessionWriteTransaction(SyncSession* session,
                                    syncable::WriteTransaction* trans)
       : session_(session) {
     DCHECK(!session_->write_transaction_);
     session_->write_transaction_ = trans;
   }
   ~ScopedSetSessionWriteTransaction() { session_->write_transaction_ = NULL; }
 
  private:
   SyncSession* session_;
   DISALLOW_COPY_AND_ASSIGN(ScopedSetSessionWriteTransaction);
 };
 
+// A utility to restrict access to only those parts of the given SyncSession
+// that pertain to the specified ModelSafeGroup.  See
+// SyncSession::ModelSafetyRestriction.
+class ScopedModelSafeGroupRestriction {
+ public:
+  ScopedModelSafeGroupRestriction(SyncSession* to_restrict,
+                               ModelSafeGroup restriction)
+      : session_(to_restrict) {
+    DCHECK(!session_->group_restriction_in_effect_);
+    session_->group_restriction_in_effect_ = true;
+    session_->group_restriction_ = restriction;
+  }
+  ~ScopedModelSafeGroupRestriction() {
+    session_->group_restriction_in_effect_ = true;
+  }
+ private:
+  SyncSession* session_;
+  DISALLOW_COPY_AND_ASSIGN(ScopedModelSafeGroupRestriction);
+};
+
 }  // namespace sessions
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_SESSIONS_SYNC_SESSION_H_