IDBObserver: Lifetime Management: Adding Observer

content/browser/indexed_db/indexed_db_dispatcher_host.h

 // Copyright (c) 2012 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_INDEXED_DB_INDEXED_DB_DISPATCHER_HOST_H_
 #define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_DISPATCHER_HOST_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 12 matching lines @@
 #include "storage/browser/quota/quota_manager.h"
 #include "storage/common/quota/quota_status_code.h"
 #include "url/gurl.h"
 
 struct IndexedDBDatabaseMetadata;
 struct IndexedDBHostMsg_DatabaseCount_Params;
 struct IndexedDBHostMsg_DatabaseCreateIndex_Params;
 struct IndexedDBHostMsg_DatabaseCreateObjectStore_Params;
 struct IndexedDBHostMsg_DatabaseCreateTransaction_Params;
 struct IndexedDBHostMsg_DatabaseDeleteRange_Params;
+struct IndexedDBHostMsg_DatabaseObserve_Params;
 struct IndexedDBHostMsg_DatabaseGet_Params;
 struct IndexedDBHostMsg_DatabaseGetAll_Params;
 struct IndexedDBHostMsg_DatabaseOpenCursor_Params;
 struct IndexedDBHostMsg_DatabasePut_Params;
 struct IndexedDBHostMsg_DatabaseSetIndexKeys_Params;
 struct IndexedDBHostMsg_FactoryDeleteDatabase_Params;
 struct IndexedDBHostMsg_FactoryGetDatabaseNames_Params;
 struct IndexedDBHostMsg_FactoryOpen_Params;
 
 namespace url {
@@ skipping 58 matching lines @@
   // id to and from a back-end ("host") transaction id that encodes the process
   // id in the high 32 bits. The mapping is host-specific and ids are validated.
   int64_t HostTransactionId(int64_t transaction_id);
   int64_t RendererTransactionId(int64_t host_transaction_id);
 
   // These are called to decode a host transaction ID, for diagnostic purposes.
   static uint32_t TransactionIdToRendererTransactionId(
       int64_t host_transaction_id);
   static uint32_t TransactionIdToProcessId(int64_t host_transaction_id);
 
+  // These are called to map a 32-bit front-end (renderer-specific) observer
+  // id to and from a back-end ("host") observer id that encodes the process
+  // id in the high 32 bits. The mapping is host-specific and ids are validated.
+  int64_t HostObserverId(int64_t observer_id);

[dmurph, 2016/06/15 12:49:43]

Why do we need these? Can we just store the ipc_thread_id and observe_id in the
observer?

It looks like you're trying to combine the ids for a map? Let's do something
like 

int64_t GenerateObserveId(int64_t ipc_thread_id, int64_t observe_id) {
  // Basic djb2 hash.
  int64_t hash = 5381;
  hash = ((hash << 5) + hash) + ipc_thread_id;
  hash = ((hash << 5) + hash) + observe_id;
  return hash;
}

[palakj1, 2016/06/16 07:05:40]

I see your point. Keeping connection_id and observer_id separate would help in
cleaning up when connection is closed or unobserve is called.
But why doesn't a simple concatenation (ipc_thread_id <<32 + observer_id) work?

[dmurph, 2016/06/16 07:30:33]

Ah, so the thread id is always int32_t, huh. Sure, that would work just fine.
just make sure you cast it to a uint64_t before you bit shift.

+  int64_t RendererObserverId(int64_t host_observer_id);
+
   std::string HoldBlobData(const IndexedDBBlobInfo& blob_info);
 
  private:
   // Friends to enable OnDestruct() delegation.
   friend class BrowserThread;
   friend class base::DeleteHelper<IndexedDBDispatcherHost>;
 
   // Used in nested classes.
   typedef std::map<std::string, std::pair<storage::BlobDataHandle*, int>>
       BlobDataHandleMap;
@@ skipping 46 matching lines @@
         const IndexedDBHostMsg_DatabaseCreateObjectStore_Params& params);
     void OnDeleteObjectStore(int32_t ipc_database_id,
                              int64_t transaction_id,
                              int64_t object_store_id);
     void OnCreateTransaction(
         const IndexedDBHostMsg_DatabaseCreateTransaction_Params&);
     void OnClose(int32_t ipc_database_id);
     void OnVersionChangeIgnored(int32_t ipc_database_id);
     void OnDestroyed(int32_t ipc_database_id);
 
+    void OnObserve(const IndexedDBHostMsg_DatabaseObserve_Params& params);
     void OnGet(const IndexedDBHostMsg_DatabaseGet_Params& params);
     void OnGetAll(const IndexedDBHostMsg_DatabaseGetAll_Params& params);
     // OnPutWrapper starts on the IO thread so that it can grab BlobDataHandles
     // before posting to the IDB TaskRunner for the rest of the job.
     void OnPutWrapper(const IndexedDBHostMsg_DatabasePut_Params& params);
     void OnPut(const IndexedDBHostMsg_DatabasePut_Params& params,
                std::vector<storage::BlobDataHandle*> handles);
     void OnSetIndexKeys(
         const IndexedDBHostMsg_DatabaseSetIndexKeys_Params& params);
     void OnSetIndexesReady(int32_t ipc_database_id,
@@ skipping 23 matching lines @@
                                      storage::QuotaStatusCode status,
                                      int64_t usage,
                                      int64_t quota);
 
     IndexedDBDispatcherHost* parent_;
     IDMap<IndexedDBConnection, IDMapOwnPointer> map_;
     WebIDBObjectIDToOriginMap database_origin_map_;
     TransactionIDToSizeMap transaction_size_map_;
     TransactionIDToOriginMap transaction_origin_map_;
     TransactionIDToDatabaseIDMap transaction_database_map_;
+    std::vector<int64_t> observers_;
 
     // Weak pointers are used when an asynchronous quota request is made, in
     // case the dispatcher is torn down before the response returns.
     base::WeakPtrFactory<DatabaseDispatcherHost> weak_factory_;
 
    private:
     DISALLOW_COPY_AND_ASSIGN(DatabaseDispatcherHost);
   };
 
   class CursorDispatcherHost {
@@ skipping 62 matching lines @@
   scoped_refptr<net::URLRequestContextGetter> request_context_getter_;
   net::URLRequestContext* request_context_;
   scoped_refptr<IndexedDBContextImpl> indexed_db_context_;
   scoped_refptr<ChromeBlobStorageContext> blob_storage_context_;
 
   BlobDataHandleMap blob_data_handle_map_;
 
   // Only access on IndexedDB thread.
   std::unique_ptr<DatabaseDispatcherHost> database_dispatcher_host_;
   std::unique_ptr<CursorDispatcherHost> cursor_dispatcher_host_;
-
   // Used to set file permissions for blob storage.
   int ipc_process_id_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(IndexedDBDispatcherHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_DISPATCHER_HOST_H_