/* -*- 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 StartupCache_h_ #define StartupCache_h_ #include "nsClassHashtable.h" #include "nsComponentManagerUtils.h" #include "nsTArray.h" #include "nsZipArchive.h" #include "nsIStartupCache.h" #include "nsITimer.h" #include "nsIMemoryReporter.h" #include "nsIObserverService.h" #include "nsIObserver.h" #include "nsIOutputStream.h" #include "nsIFile.h" #include "mozilla/Attributes.h" #include "mozilla/MemoryReporting.h" #include "mozilla/StaticPtr.h" #include "mozilla/UniquePtr.h" /** * The StartupCache is a persistent cache of simple key-value pairs, * where the keys are null-terminated c-strings and the values are * arbitrary data, passed as a (char*, size) tuple. * * Clients should use the GetSingleton() static method to access the cache. It * will be available from the end of XPCOM init (NS_InitXPCOM3 in XPCOMInit.cpp), * until XPCOM shutdown begins. The GetSingleton() method will return null if the cache * is unavailable. The cache is only provided for libxul builds -- * it will fail to link in non-libxul builds. The XPCOM interface is provided * only to allow compiled-code tests; clients should avoid using it. * * The API provided is very simple: GetBuffer() returns a buffer that was previously * stored in the cache (if any), and PutBuffer() inserts a buffer into the cache. * GetBuffer returns a new buffer, and the caller must take ownership of it. * PutBuffer will assert if the client attempts to insert a buffer with the same name as * an existing entry. The cache makes a copy of the passed-in buffer, so client * retains ownership. * * InvalidateCache() may be called if a client suspects data corruption * or wishes to invalidate for any other reason. This will remove all existing cache data. * Additionally, the static method IgnoreDiskCache() can be called if it is * believed that the on-disk cache file is itself corrupt. This call implicitly * calls InvalidateCache (if the singleton has been initialized) to ensure any * data already read from disk is discarded. The cache will not load data from * the disk file until a successful write occurs. * * Finally, getDebugObjectOutputStream() allows debug code to wrap an objectstream * with a debug objectstream, to check for multiply-referenced objects. These will * generally fail to deserialize correctly, unless they are stateless singletons or the * client maintains their own object data map for deserialization. * * Writes before the final-ui-startup notification are placed in an intermediate * cache in memory, then written out to disk at a later time, to get writes off the * startup path. In any case, clients should not rely on being able to GetBuffer() * data that is written to the cache, since it may not have been written to disk or * another client may have invalidated the cache. In other words, it should be used as * a cache only, and not a reliable persistent store. * * Some utility functions are provided in StartupCacheUtils. These functions wrap the * buffers into object streams, which may be useful for serializing objects. Note * the above caution about multiply-referenced objects, though -- the streams are just * as 'dumb' as the underlying buffers about multiply-referenced objects. They just * provide some convenience in writing out data. */ namespace mozilla { namespace scache { struct CacheEntry { UniquePtr<char[]> data; uint32_t size; CacheEntry() : size(0) { } // Takes possession of buf CacheEntry(UniquePtr<char[]> buf, uint32_t len) : data(Move(buf)), size(len) { } ~CacheEntry() { } size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) { return mallocSizeOf(this) + mallocSizeOf(data.get()); } }; // We don't want to refcount StartupCache, and ObserverService wants to // refcount its listeners, so we'll let it refcount this instead. class StartupCacheListener final : public nsIObserver { ~StartupCacheListener() {} NS_DECL_THREADSAFE_ISUPPORTS NS_DECL_NSIOBSERVER }; class StartupCache : public nsIMemoryReporter { friend class StartupCacheListener; friend class StartupCacheWrapper; public: NS_DECL_THREADSAFE_ISUPPORTS NS_DECL_NSIMEMORYREPORTER // StartupCache methods. See above comments for a more detailed description. // Returns a buffer that was previously stored, caller takes ownership. nsresult GetBuffer(const char* id, UniquePtr<char[]>* outbuf, uint32_t* length); // Stores a buffer. Caller keeps ownership, we make a copy. nsresult PutBuffer(const char* id, const char* inbuf, uint32_t length); // Removes the cache file. void InvalidateCache(); // Signal that data should not be loaded from the cache file static void IgnoreDiskCache(); // In DEBUG builds, returns a stream that will attempt to check for // and disallow multiple writes of the same object. nsresult GetDebugObjectOutputStream(nsIObjectOutputStream* aStream, nsIObjectOutputStream** outStream); nsresult RecordAgesAlways(); static StartupCache* GetSingleton(); static void DeleteSingleton(); // This measures all the heap memory used by the StartupCache, i.e. it // excludes the mapping. size_t HeapSizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const; size_t SizeOfMapping(); private: StartupCache(); virtual ~StartupCache(); enum TelemetrifyAge { IGNORE_AGE = 0, RECORD_AGE = 1 }; static enum TelemetrifyAge gPostFlushAgeAction; nsresult LoadArchive(enum TelemetrifyAge flag); nsresult Init(); void WriteToDisk(); nsresult ResetStartupWriteTimer(); void WaitOnWriteThread(); static nsresult InitSingleton(); static void WriteTimeout(nsITimer *aTimer, void *aClosure); static void ThreadedWrite(void *aClosure); nsClassHashtable<nsCStringHashKey, CacheEntry> mTable; nsTArray<nsCString> mPendingWrites; RefPtr<nsZipArchive> mArchive; nsCOMPtr<nsIFile> mFile; nsCOMPtr<nsIObserverService> mObserverService; RefPtr<StartupCacheListener> mListener; nsCOMPtr<nsITimer> mTimer; bool mStartupWriteInitiated; static StaticRefPtr<StartupCache> gStartupCache; static bool gShutdownInitiated; static bool gIgnoreDiskCache; PRThread *mWriteThread; #ifdef DEBUG nsTHashtable<nsISupportsHashKey> mWriteObjectMap; #endif }; // This debug outputstream attempts to detect if clients are writing multiple // references to the same object. We only support that if that object // is a singleton. #ifdef DEBUG class StartupCacheDebugOutputStream final : public nsIObjectOutputStream { ~StartupCacheDebugOutputStream() {} NS_DECL_ISUPPORTS NS_DECL_NSIOBJECTOUTPUTSTREAM StartupCacheDebugOutputStream (nsIObjectOutputStream* binaryStream, nsTHashtable<nsISupportsHashKey>* objectMap) : mBinaryStream(binaryStream), mObjectMap(objectMap) { } NS_FORWARD_SAFE_NSIBINARYOUTPUTSTREAM(mBinaryStream) NS_FORWARD_SAFE_NSIOUTPUTSTREAM(mBinaryStream) bool CheckReferences(nsISupports* aObject); nsCOMPtr<nsIObjectOutputStream> mBinaryStream; nsTHashtable<nsISupportsHashKey> *mObjectMap; }; #endif // DEBUG // XPCOM wrapper interface provided for tests only. #define NS_STARTUPCACHE_CID \ {0xae4505a9, 0x87ab, 0x477c, \ {0xb5, 0x77, 0xf9, 0x23, 0x57, 0xed, 0xa8, 0x84}} // contract id: "@mozilla.org/startupcache/cache;1" class StartupCacheWrapper final : public nsIStartupCache { ~StartupCacheWrapper(); NS_DECL_THREADSAFE_ISUPPORTS NS_DECL_NSISTARTUPCACHE static StartupCacheWrapper* GetSingleton(); static StartupCacheWrapper *gStartupCacheWrapper; }; } // namespace scache } // namespace mozilla #endif //StartupCache_h_