storage/mozStorageService.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef MOZSTORAGESERVICE_H
   8 #define MOZSTORAGESERVICE_H
   9
  10 #include "nsCOMPtr.h"
  11 #include "nsICollation.h"
  12 #include "nsIFile.h"
  13 #include "nsIMemoryReporter.h"
  14 #include "nsIObserver.h"
  15 #include "nsTArray.h"
  16 #include "mozilla/Mutex.h"
  17
  18 #include "mozIStorageService.h"
  19
  20 class nsIMemoryReporter;
  21 struct sqlite3_vfs;
  22
  23 namespace mozilla {
  24 namespace storage {
  25
  26 class Connection;
  27 class Service : public mozIStorageService,
  28                 public nsIObserver,
  29                 public nsIMemoryReporter {
  30  public:
  31   /**
  32    * Initializes the service.  This must be called before any other function!
  33    */
  34   nsresult initialize();
  35
  36   /**
  37    * Compares two strings using the Service's locale-aware collation.
  38    *
  39    * @param  aStr1
  40    *         The string to be compared against aStr2.
  41    * @param  aStr2
  42    *         The string to be compared against aStr1.
  43    * @param  aComparisonStrength
  44    *         The sorting strength, one of the nsICollation constants.
  45    * @return aStr1 - aStr2.  That is, if aStr1 < aStr2, returns a negative
  46    *         number.  If aStr1 > aStr2, returns a positive number.  If
  47    *         aStr1 == aStr2, returns 0.
  48    */
  49   int localeCompareStrings(const nsAString& aStr1, const nsAString& aStr2,
  50                            int32_t aComparisonStrength);
  51
  52   static already_AddRefed<Service> getSingleton();
  53
  54   NS_DECL_THREADSAFE_ISUPPORTS
  55   NS_DECL_MOZISTORAGESERVICE
  56   NS_DECL_NSIOBSERVER
  57   NS_DECL_NSIMEMORYREPORTER
  58
  59   /**
  60    * Returns a boolean value indicating whether or not the given page size is
  61    * valid (currently understood as a power of 2 between 512 and 65536).
  62    */
  63   static bool pageSizeIsValid(int32_t aPageSize) {
  64     return aPageSize == 512 || aPageSize == 1024 || aPageSize == 2048 ||
  65            aPageSize == 4096 || aPageSize == 8192 || aPageSize == 16384 ||
  66            aPageSize == 32768 || aPageSize == 65536;
  67   }
  68
  69   static const int32_t kDefaultPageSize = 32768;
  70
  71   /**
  72    * Registers the connection with the storage service.  Connections are
  73    * registered so they can be iterated over.
  74    *
  75    * @pre mRegistrationMutex is not held
  76    *
  77    * @param  aConnection
  78    *         The connection to register.
  79    */
  80   void registerConnection(Connection* aConnection);
  81
  82   /**
  83    * Unregisters the connection with the storage service.
  84    *
  85    * @pre mRegistrationMutex is not held
  86    *
  87    * @param  aConnection
  88    *         The connection to unregister.
  89    */
  90   void unregisterConnection(Connection* aConnection);
  91
  92   /**
  93    * Gets the list of open connections.  Note that you must test each
  94    * connection with mozIStorageConnection::connectionReady before doing
  95    * anything with it, and skip it if it's not ready.
  96    *
  97    * @pre mRegistrationMutex is not held
  98    *
  99    * @param  aConnections
 100    *         An inout param;  it is cleared and the connections are appended to
 101    *         it.
 102    * @return The open connections.
 103    */
 104   void getConnections(nsTArray<RefPtr<Connection> >& aConnections);
 105
 106  private:
 107   Service();
 108   virtual ~Service();
 109
 110   /**
 111    * Used for 1) locking around calls when initializing connections so that we
 112    * can ensure that the state of sqlite3_enable_shared_cache is sane and 2)
 113    * synchronizing access to mLocaleCollation.
 114    */
 115   Mutex mMutex;
 116
 117   struct AutoVFSRegistration {
 118     int Init(UniquePtr<sqlite3_vfs> aVFS);
 119     ~AutoVFSRegistration();
 120
 121    private:
 122     UniquePtr<sqlite3_vfs> mVFS;
 123   };
 124
 125   // The order of these members should match the order of Init calls in
 126   // initialize(), to ensure that the unregistration takes place in the reverse
 127   // order.
 128   AutoVFSRegistration mTelemetrySqliteVFS;
 129   AutoVFSRegistration mTelemetryExclSqliteVFS;
 130   AutoVFSRegistration mObfuscatingSqliteVFS;
 131
 132   /**
 133    * Protects mConnections.
 134    */
 135   Mutex mRegistrationMutex;
 136
 137   /**
 138    * The list of connections we have created.  Modifications to it are
 139    * protected by |mRegistrationMutex|.
 140    */
 141   nsTArray<RefPtr<Connection> > mConnections;
 142
 143   /**
 144    * Frees as much heap memory as possible from all of the known open
 145    * connections.
 146    */
 147   void minimizeMemory();
 148
 149   /**
 150    * Lazily creates and returns a collation created from the application's
 151    * locale that all statements of all Connections of this Service may use.
 152    * Since the collation's lifetime is that of the Service and no statement may
 153    * execute outside the lifetime of the Service, this method returns a raw
 154    * pointer.
 155    */
 156   nsICollation* getLocaleCollation();
 157
 158   /**
 159    * Lazily created collation that all statements of all Connections of this
 160    * Service may use.  The collation is created from the application's locale.
 161    *
 162    * @note Collation implementations are platform-dependent and in general not
 163    *       thread-safe.  Access to this collation should be synchronized.
 164    */
 165   nsCOMPtr<nsICollation> mLocaleCollation;
 166
 167   nsCOMPtr<nsIFile> mProfileStorageFile;
 168
 169   nsCOMPtr<nsIMemoryReporter> mStorageSQLiteReporter;
 170
 171   static Service* gService;
 172 };
 173
 174 }  // namespace storage
 175 }  // namespace mozilla
 176
 177 #endif /* MOZSTORAGESERVICE_H */