mirror of
https://github.com/classilla/tenfourfox.git
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230 lines
7.7 KiB
C++
230 lines
7.7 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef StartupCache_h_
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#define StartupCache_h_
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#include "nsClassHashtable.h"
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#include "nsComponentManagerUtils.h"
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#include "nsTArray.h"
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#include "nsZipArchive.h"
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#include "nsIStartupCache.h"
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#include "nsITimer.h"
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#include "nsIMemoryReporter.h"
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#include "nsIObserverService.h"
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#include "nsIObserver.h"
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#include "nsIOutputStream.h"
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#include "nsIFile.h"
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#include "mozilla/Attributes.h"
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#include "mozilla/MemoryReporting.h"
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#include "mozilla/StaticPtr.h"
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/**
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* The StartupCache is a persistent cache of simple key-value pairs,
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* where the keys are null-terminated c-strings and the values are
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* arbitrary data, passed as a (char*, size) tuple.
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*
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* Clients should use the GetSingleton() static method to access the cache. It
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* will be available from the end of XPCOM init (NS_InitXPCOM3 in XPCOMInit.cpp),
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* until XPCOM shutdown begins. The GetSingleton() method will return null if the cache
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* is unavailable. The cache is only provided for libxul builds --
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* it will fail to link in non-libxul builds. The XPCOM interface is provided
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* only to allow compiled-code tests; clients should avoid using it.
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*
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* The API provided is very simple: GetBuffer() returns a buffer that was previously
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* stored in the cache (if any), and PutBuffer() inserts a buffer into the cache.
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* GetBuffer returns a new buffer, and the caller must take ownership of it.
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* PutBuffer will assert if the client attempts to insert a buffer with the same name as
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* an existing entry. The cache makes a copy of the passed-in buffer, so client
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* retains ownership.
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*
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* InvalidateCache() may be called if a client suspects data corruption
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* or wishes to invalidate for any other reason. This will remove all existing cache data.
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* Additionally, the static method IgnoreDiskCache() can be called if it is
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* believed that the on-disk cache file is itself corrupt. This call implicitly
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* calls InvalidateCache (if the singleton has been initialized) to ensure any
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* data already read from disk is discarded. The cache will not load data from
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* the disk file until a successful write occurs.
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*
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* Finally, getDebugObjectOutputStream() allows debug code to wrap an objectstream
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* with a debug objectstream, to check for multiply-referenced objects. These will
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* generally fail to deserialize correctly, unless they are stateless singletons or the
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* client maintains their own object data map for deserialization.
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*
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* Writes before the final-ui-startup notification are placed in an intermediate
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* cache in memory, then written out to disk at a later time, to get writes off the
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* startup path. In any case, clients should not rely on being able to GetBuffer()
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* data that is written to the cache, since it may not have been written to disk or
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* another client may have invalidated the cache. In other words, it should be used as
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* a cache only, and not a reliable persistent store.
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*
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* Some utility functions are provided in StartupCacheUtils. These functions wrap the
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* buffers into object streams, which may be useful for serializing objects. Note
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* the above caution about multiply-referenced objects, though -- the streams are just
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* as 'dumb' as the underlying buffers about multiply-referenced objects. They just
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* provide some convenience in writing out data.
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*/
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namespace mozilla {
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namespace scache {
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struct CacheEntry
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{
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nsAutoArrayPtr<char> data;
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uint32_t size;
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CacheEntry() : data(nullptr), size(0) { }
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// Takes possession of buf
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CacheEntry(char* buf, uint32_t len) : data(buf), size(len) { }
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~CacheEntry()
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{
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}
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size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) {
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return mallocSizeOf(this) + mallocSizeOf(data);
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}
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};
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// We don't want to refcount StartupCache, and ObserverService wants to
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// refcount its listeners, so we'll let it refcount this instead.
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class StartupCacheListener final : public nsIObserver
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{
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~StartupCacheListener() {}
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NS_DECL_THREADSAFE_ISUPPORTS
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NS_DECL_NSIOBSERVER
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};
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class StartupCache : public nsIMemoryReporter
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{
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friend class StartupCacheListener;
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friend class StartupCacheWrapper;
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public:
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NS_DECL_THREADSAFE_ISUPPORTS
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NS_DECL_NSIMEMORYREPORTER
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// StartupCache methods. See above comments for a more detailed description.
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// Returns a buffer that was previously stored, caller takes ownership.
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nsresult GetBuffer(const char* id, char** outbuf, uint32_t* length);
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// Stores a buffer. Caller keeps ownership, we make a copy.
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nsresult PutBuffer(const char* id, const char* inbuf, uint32_t length);
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// Removes the cache file.
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void InvalidateCache();
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// Signal that data should not be loaded from the cache file
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static void IgnoreDiskCache();
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// In DEBUG builds, returns a stream that will attempt to check for
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// and disallow multiple writes of the same object.
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nsresult GetDebugObjectOutputStream(nsIObjectOutputStream* aStream,
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nsIObjectOutputStream** outStream);
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nsresult RecordAgesAlways();
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static StartupCache* GetSingleton();
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static void DeleteSingleton();
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// This measures all the heap memory used by the StartupCache, i.e. it
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// excludes the mapping.
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size_t HeapSizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
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size_t SizeOfMapping();
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private:
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StartupCache();
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virtual ~StartupCache();
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enum TelemetrifyAge {
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IGNORE_AGE = 0,
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RECORD_AGE = 1
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};
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static enum TelemetrifyAge gPostFlushAgeAction;
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nsresult LoadArchive(enum TelemetrifyAge flag);
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nsresult Init();
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void WriteToDisk();
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nsresult ResetStartupWriteTimer();
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void WaitOnWriteThread();
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static nsresult InitSingleton();
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static void WriteTimeout(nsITimer *aTimer, void *aClosure);
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static void ThreadedWrite(void *aClosure);
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nsClassHashtable<nsCStringHashKey, CacheEntry> mTable;
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nsTArray<nsCString> mPendingWrites;
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RefPtr<nsZipArchive> mArchive;
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nsCOMPtr<nsIFile> mFile;
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nsCOMPtr<nsIObserverService> mObserverService;
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RefPtr<StartupCacheListener> mListener;
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nsCOMPtr<nsITimer> mTimer;
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bool mStartupWriteInitiated;
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static StaticRefPtr<StartupCache> gStartupCache;
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static bool gShutdownInitiated;
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static bool gIgnoreDiskCache;
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PRThread *mWriteThread;
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#ifdef DEBUG
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nsTHashtable<nsISupportsHashKey> mWriteObjectMap;
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#endif
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};
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// This debug outputstream attempts to detect if clients are writing multiple
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// references to the same object. We only support that if that object
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// is a singleton.
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#ifdef DEBUG
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class StartupCacheDebugOutputStream final
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: public nsIObjectOutputStream
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{
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~StartupCacheDebugOutputStream() {}
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NS_DECL_ISUPPORTS
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NS_DECL_NSIOBJECTOUTPUTSTREAM
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StartupCacheDebugOutputStream (nsIObjectOutputStream* binaryStream,
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nsTHashtable<nsISupportsHashKey>* objectMap)
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: mBinaryStream(binaryStream), mObjectMap(objectMap) { }
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NS_FORWARD_SAFE_NSIBINARYOUTPUTSTREAM(mBinaryStream)
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NS_FORWARD_SAFE_NSIOUTPUTSTREAM(mBinaryStream)
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bool CheckReferences(nsISupports* aObject);
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nsCOMPtr<nsIObjectOutputStream> mBinaryStream;
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nsTHashtable<nsISupportsHashKey> *mObjectMap;
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};
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#endif // DEBUG
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// XPCOM wrapper interface provided for tests only.
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#define NS_STARTUPCACHE_CID \
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{0xae4505a9, 0x87ab, 0x477c, \
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{0xb5, 0x77, 0xf9, 0x23, 0x57, 0xed, 0xa8, 0x84}}
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// contract id: "@mozilla.org/startupcache/cache;1"
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class StartupCacheWrapper final
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: public nsIStartupCache
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{
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~StartupCacheWrapper();
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NS_DECL_THREADSAFE_ISUPPORTS
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NS_DECL_NSISTARTUPCACHE
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static StartupCacheWrapper* GetSingleton();
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static StartupCacheWrapper *gStartupCacheWrapper;
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};
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} // namespace scache
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} // namespace mozilla
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#endif //StartupCache_h_
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