The Tor Browser: dom/src/storage/DOMStorageDBThread.h@b8a032363ba2 (annotated)

dom/src/storage/DOMStorageDBThread.h@b8a032363ba2 (annotated)

dom/src/storage/DOMStorageDBThread.h

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #ifndef DOMStorageDBThread_h___
 #define DOMStorageDBThread_h___
 #include "prthread.h"
 #include "prinrval.h"
 #include "nsTArray.h"
 #include "mozilla/Monitor.h"
 #include "mozilla/storage/StatementCache.h"
 #include "nsString.h"
 #include "nsCOMPtr.h"
 #include "nsClassHashtable.h"
 #include "nsIFile.h"
 class mozIStorageConnection;
 namespace mozilla {
 namespace dom {
 class DOMStorageCacheBridge;
 class DOMStorageUsageBridge;
 class DOMStorageUsage;
 typedef mozilla::storage::StatementCache<mozIStorageStatement> StatementCache;
 // Interface used by the cache to post operations to the asynchronous
 // database thread or process.
 class DOMStorageDBBridge
 {
 public:
   DOMStorageDBBridge();
   virtual ~DOMStorageDBBridge() {}
   // Ensures the database engine is started
   virtual nsresult Init() = 0;
   // Releases the database and disallows its usage
   virtual nsresult Shutdown() = 0;
   // Asynchronously fills the cache with data from the database for first use.
   // When |aPriority| is true, the preload operation is scheduled as the first one.
   // This method is responsible to keep hard reference to the cache for the time of
   // the preload or, when preload cannot be performed, call LoadDone() immediately.
   virtual void AsyncPreload(DOMStorageCacheBridge* aCache, bool aPriority = false) = 0;
   // Asynchronously fill the |usage| object with actual usage of data by its scope.
   // The scope is eTLD+1 tops, never deeper subdomains.
   virtual void AsyncGetUsage(DOMStorageUsageBridge* aUsage) = 0;
   // Synchronously fills the cache, when |aForceSync| is false and cache already got some
   // data before, the method waits for the running preload to finish
   virtual void SyncPreload(DOMStorageCacheBridge* aCache, bool aForceSync = false) = 0;
   // Called when an existing key is modified in the storage, schedules update to the database
   virtual nsresult AsyncAddItem(DOMStorageCacheBridge* aCache, const nsAString& aKey, const nsAString& aValue) = 0;
   // Called when an existing key is modified in the storage, schedules update to the database
   virtual nsresult AsyncUpdateItem(DOMStorageCacheBridge* aCache, const nsAString& aKey, const nsAString& aValue) = 0;
   // Called when an item is removed from the storage, schedules delete of the key
   virtual nsresult AsyncRemoveItem(DOMStorageCacheBridge* aCache, const nsAString& aKey) = 0;
   // Called when the whole storage is cleared by the DOM API, schedules delete of the scope
   virtual nsresult AsyncClear(DOMStorageCacheBridge* aCache) = 0;
   // Called when chrome deletes e.g. cookies, schedules delete of the whole database
   virtual void AsyncClearAll() = 0;
   // Called when only a domain and its subdomains or an app data is about to clear
   virtual void AsyncClearMatchingScope(const nsACString& aScope) = 0;
   // Forces scheduled DB operations to be early flushed to the disk
   virtual void AsyncFlush() = 0;
   // Check whether the scope has any data stored on disk and is thus allowed to preload
   virtual bool ShouldPreloadScope(const nsACString& aScope) = 0;
   // Get the complete list of scopes having data
   virtual void GetScopesHavingData(InfallibleTArray<nsCString>* aScopes) = 0;
 };
 // The implementation of the the database engine, this directly works
 // with the sqlite or any other db API we are based on
 // This class is resposible for collecting and processing asynchronous
 // DB operations over caches (DOMStorageCache) communicating though
 // DOMStorageCacheBridge interface class
 class DOMStorageDBThread MOZ_FINAL : public DOMStorageDBBridge
 {
 public:
   class PendingOperations;
   // Representation of a singe database task, like adding and removing keys,
   // (pre)loading the whole origin data, cleaning.
   class DBOperation
   {
   public:
     typedef enum {
       // Only operation that reads data from the database
       opPreload,
       // The same as opPreload, just executed with highest priority
       opPreloadUrgent,
       // Load usage of a scope
       opGetUsage,
       // Operations invoked by the DOM content API
       opAddItem,
       opUpdateItem,
       opRemoveItem,
       opClear,
       // Operations invoked by chrome
       opClearAll,
       opClearMatchingScope,
     } OperationType;
     DBOperation(const OperationType aType,
                 DOMStorageCacheBridge* aCache = nullptr,
                 const nsAString& aKey = EmptyString(),
                 const nsAString& aValue = EmptyString());
     DBOperation(const OperationType aType,
                 DOMStorageUsageBridge* aUsage);
     DBOperation(const OperationType aType,
                 const nsACString& aScope);
     ~DBOperation();
     // Executes the operation, doesn't necessarity have to be called on the I/O thread
     void PerformAndFinalize(DOMStorageDBThread* aThread);
     // Finalize the operation, i.e. do any internal cleanup and finish calls
     void Finalize(nsresult aRv);
     // The operation type
     OperationType Type() { return mType; }
     // The operation scope (=origin)
     const nsCString Scope();
     // |Scope + key| the operation is working with
     const nsCString Target();
   private:
     // The operation implementation body
     nsresult Perform(DOMStorageDBThread* aThread);
     friend class PendingOperations;
     OperationType mType;
     nsRefPtr<DOMStorageCacheBridge> mCache;
     nsRefPtr<DOMStorageUsageBridge> mUsage;
     nsString mKey;
     nsString mValue;
     nsCString mScope;
   };
   // Encapsulation of collective and coalescing logic for all pending operations
   // except preloads that are handled separately as priority operations
   class PendingOperations {
   public:
     PendingOperations();
     // Method responsible for coalescing redundant update operations with the same
     // |Target()| or clear operations with the same or matching |Scope()|
     void Add(DBOperation* aOperation);
     // True when there are some scheduled operations to flush on disk
     bool HasTasks();
     // Moves collected operations to a local flat list to allow execution of the operation
     // list out of the thread lock
     bool Prepare();
     // Executes the previously |Prepared()'ed| list of operations, retuns result, but doesn't
     // handle it in any way in case of a failure
     nsresult Execute(DOMStorageDBThread* aThread);
     // Finalizes the pending operation list, returns false when too many operations failed
     // to flush what indicates a long standing issue with the database access.
     bool Finalize(nsresult aRv);
     // true when a clear that deletes the given |scope| is among the pending operations;
     // when a preload for that scope is being scheduled, it must be finished right away
     bool IsScopeClearPending(const nsACString& aScope);
     // Checks whether there is a pending update (or clear, actually) operation for this scope.
     bool IsScopeUpdatePending(const nsACString& aScope);
   private:
     // Returns true iff new operation is of type newType and there is a pending
     // operation of type pendingType for the same key (target).
     bool CheckForCoalesceOpportunity(DBOperation* aNewOp,
                                      DBOperation::OperationType aPendingType,
                                      DBOperation::OperationType aNewType);
     // List of all clearing operations, executed first
     nsClassHashtable<nsCStringHashKey, DBOperation> mClears;
     // List of all update/insert operations, executed as second
     nsClassHashtable<nsCStringHashKey, DBOperation> mUpdates;
     // Collection of all tasks, valid only between Prepare() and Execute()
     nsTArray<nsAutoPtr<DBOperation> > mExecList;
     // Number of failing flush attempts
     uint32_t mFlushFailureCount;
   };
 public:
   DOMStorageDBThread();
   virtual ~DOMStorageDBThread() {}
   virtual nsresult Init();
   virtual nsresult Shutdown();
   virtual void AsyncPreload(DOMStorageCacheBridge* aCache, bool aPriority = false)
     { InsertDBOp(new DBOperation(aPriority ? DBOperation::opPreloadUrgent : DBOperation::opPreload, aCache)); }
   virtual void SyncPreload(DOMStorageCacheBridge* aCache, bool aForce = false);
   virtual void AsyncGetUsage(DOMStorageUsageBridge * aUsage)
     { InsertDBOp(new DBOperation(DBOperation::opGetUsage, aUsage)); }
   virtual nsresult AsyncAddItem(DOMStorageCacheBridge* aCache, const nsAString& aKey, const nsAString& aValue)
     { return InsertDBOp(new DBOperation(DBOperation::opAddItem, aCache, aKey, aValue)); }
   virtual nsresult AsyncUpdateItem(DOMStorageCacheBridge* aCache, const nsAString& aKey, const nsAString& aValue)
     { return InsertDBOp(new DBOperation(DBOperation::opUpdateItem, aCache, aKey, aValue)); }
   virtual nsresult AsyncRemoveItem(DOMStorageCacheBridge* aCache, const nsAString& aKey)
     { return InsertDBOp(new DBOperation(DBOperation::opRemoveItem, aCache, aKey)); }
   virtual nsresult AsyncClear(DOMStorageCacheBridge* aCache)
     { return InsertDBOp(new DBOperation(DBOperation::opClear, aCache)); }
   virtual void AsyncClearAll()
     { InsertDBOp(new DBOperation(DBOperation::opClearAll)); }
   virtual void AsyncClearMatchingScope(const nsACString& aScope)
     { InsertDBOp(new DBOperation(DBOperation::opClearMatchingScope, aScope)); }
   virtual void AsyncFlush();
   virtual bool ShouldPreloadScope(const nsACString& aScope);
   virtual void GetScopesHavingData(InfallibleTArray<nsCString>* aScopes);
 private:
   nsCOMPtr<nsIFile> mDatabaseFile;
   PRThread* mThread;
   // The monitor we drive the thread with
   Monitor mMonitor;
   // Flag to stop, protected by the monitor
   bool mStopIOThread;
   // Whether WAL is enabled
   bool mWALModeEnabled;
   // Whether DB has already been open, avoid races between main thread reads
   // and pending DB init in the background I/O thread
   bool mDBReady;
   // State of the database initiation
   nsresult mStatus;
   // List of scopes having data, for optimization purposes only
   nsTHashtable<nsCStringHashKey> mScopesHavingData;
   StatementCache mWorkerStatements;
   StatementCache mReaderStatements;
   // Connection used by the worker thread for all read and write ops
   nsCOMPtr<mozIStorageConnection> mWorkerConnection;
   // Connection used only on the main thread for sync read operations
   nsCOMPtr<mozIStorageConnection> mReaderConnection;
   // Time the first pending operation has been added to the pending operations
   // list
   PRIntervalTime mDirtyEpoch;
   // Flag to force immediate flush of all pending operations
   bool mFlushImmediately;
   // List of preloading operations, in chronological or priority order.
   // Executed prioritly over pending update operations.
   nsTArray<DBOperation*> mPreloads;
   // Collector of pending update operations
   PendingOperations mPendingTasks;
   // Counter of calls for thread priority rising.
   int32_t mPriorityCounter;
   // Helper to direct an operation to one of the arrays above;
   // also checks IsScopeClearPending for preloads
   nsresult InsertDBOp(DBOperation* aOperation);
   // Opens the database, first thing we do after start of the thread.
   nsresult OpenDatabaseConnection();
   nsresult InitDatabase();
   nsresult ShutdownDatabase();
   // Tries to establish WAL mode
   nsresult SetJournalMode(bool aIsWal);
   nsresult TryJournalMode();
   // Sets the threshold for auto-checkpointing the WAL.
   nsresult ConfigureWALBehavior();
   void SetHigherPriority();
   void SetDefaultPriority();
   // Ensures we flush pending tasks in some reasonble time
   void ScheduleFlush();
   // Called when flush of pending tasks is being executed
   void UnscheduleFlush();
   // This method is used for two purposes:
   // 1. as a value passed to monitor.Wait() method
   // 2. as in indicator that flush has to be performed
   //
   // Return:
   // - PR_INTERVAL_NO_TIMEOUT when no pending tasks are scheduled
   // - larger then zero when tasks have been scheduled, but it is
   //   still not time to perform the flush ; it is actual interval
   //   time to wait until the flush has to happen
   // - 0 when it is time to do the flush
   PRIntervalTime TimeUntilFlush();
   // Notifies to the main thread that flush has completed
   void NotifyFlushCompletion();
   // Thread loop
   static void ThreadFunc(void* aArg);
   void ThreadFunc();
 };
 } // ::dom
 } // ::mozilla
 #endif /* DOMStorageDBThread_h___ */

The Tor Browser / annotate

dom/src/storage/DOMStorageDBThread.h@b8a032363ba2 (annotated)

dom/src/storage/DOMStorageDBThread.h