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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef COMPONENTS_INVALIDATION_INVALIDATION_SERVICE_H_
      6 #define COMPONENTS_INVALIDATION_INVALIDATION_SERVICE_H_
      7 
      8 #include "base/callback_forward.h"
      9 #include "components/invalidation/invalidation_util.h"
     10 #include "components/invalidation/invalidator_state.h"
     11 
     12 class IdentityProvider;
     13 
     14 namespace syncer {
     15 class InvalidationHandler;
     16 }  // namespace syncer
     17 
     18 namespace invalidation {
     19 class InvalidationLogger;
     20 
     21 // Interface for classes that handle invalidation registrations and send out
     22 // invalidations to register handlers.
     23 //
     24 // Invalidation clients should follow the pattern below:
     25 //
     26 // When starting the client:
     27 //
     28 //   frontend->RegisterInvalidationHandler(client_handler);
     29 //
     30 // When the set of IDs to register changes for the client during its lifetime
     31 // (i.e., between calls to RegisterInvalidationHandler(client_handler) and
     32 // UnregisterInvalidationHandler(client_handler):
     33 //
     34 //   frontend->UpdateRegisteredInvalidationIds(client_handler, client_ids);
     35 //
     36 // When shutting down the client for browser shutdown:
     37 //
     38 //   frontend->UnregisterInvalidationHandler(client_handler);
     39 //
     40 // Note that there's no call to UpdateRegisteredIds() -- this is because the
     41 // invalidation API persists registrations across browser restarts.
     42 //
     43 // When permanently shutting down the client, e.g. when disabling the related
     44 // feature:
     45 //
     46 //   frontend->UpdateRegisteredInvalidationIds(client_handler, ObjectIdSet());
     47 //   frontend->UnregisterInvalidationHandler(client_handler);
     48 //
     49 // If an invalidation handler cares about the invalidator state, it should also
     50 // do the following when starting the client:
     51 //
     52 //   invalidator_state = frontend->GetInvalidatorState();
     53 //
     54 // It can also do the above in OnInvalidatorStateChange(), or it can use the
     55 // argument to OnInvalidatorStateChange().
     56 //
     57 // It is an error to have registered handlers when an
     58 // InvalidationFrontend is shut down; clients must ensure that they
     59 // unregister themselves before then. (Depending on the
     60 // InvalidationFrontend, shutdown may be equivalent to destruction, or
     61 // a separate function call like Shutdown()).
     62 //
     63 // NOTE(akalin): Invalidations that come in during browser shutdown may get
     64 // dropped.  This won't matter once we have an Acknowledge API, though: see
     65 // http://crbug.com/78462 and http://crbug.com/124149.
     66 class InvalidationService {
     67  public:
     68   virtual ~InvalidationService() {}
     69 
     70   // Starts sending notifications to |handler|.  |handler| must not be NULL,
     71   // and it must not already be registered.
     72   //
     73   // Handler registrations are persisted across restarts of sync.
     74   virtual void RegisterInvalidationHandler(
     75       syncer::InvalidationHandler* handler) = 0;
     76 
     77   // Updates the set of ObjectIds associated with |handler|.  |handler| must
     78   // not be NULL, and must already be registered.  An ID must be registered for
     79   // at most one handler.
     80   //
     81   // Registered IDs are persisted across restarts of sync.
     82   virtual void UpdateRegisteredInvalidationIds(
     83       syncer::InvalidationHandler* handler,
     84       const syncer::ObjectIdSet& ids) = 0;
     85 
     86   // Stops sending notifications to |handler|.  |handler| must not be NULL, and
     87   // it must already be registered.  Note that this doesn't unregister the IDs
     88   // associated with |handler|.
     89   //
     90   // Handler registrations are persisted across restarts of sync.
     91   virtual void UnregisterInvalidationHandler(
     92       syncer::InvalidationHandler* handler) = 0;
     93 
     94   // Returns the current invalidator state.  When called from within
     95   // InvalidationHandler::OnInvalidatorStateChange(), this must return
     96   // the updated state.
     97   virtual syncer::InvalidatorState GetInvalidatorState() const = 0;
     98 
     99   // Returns the ID belonging to this invalidation client.  Can be used to
    100   // prevent the receipt of notifications of our own changes.
    101   virtual std::string GetInvalidatorClientId() const = 0;
    102 
    103   // Return the logger used to debug invalidations
    104   virtual InvalidationLogger* GetInvalidationLogger() = 0;
    105 
    106   // Triggers requests of internal status.
    107   virtual void RequestDetailedStatus(
    108       base::Callback<void(const base::DictionaryValue&)> post_caller) const = 0;
    109 
    110   // Returns the identity provider.
    111   virtual IdentityProvider* GetIdentityProvider() = 0;
    112 };
    113 
    114 }  // namespace invalidation
    115 
    116 #endif  // COMPONENTS_INVALIDATION_INVALIDATION_SERVICE_H_
    117