1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/startupcache/StartupCache.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,226 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#ifndef StartupCache_h_
1.10 +#define StartupCache_h_
1.11 +
1.12 +#include "nsClassHashtable.h"
1.13 +#include "nsComponentManagerUtils.h"
1.14 +#include "nsZipArchive.h"
1.15 +#include "nsIStartupCache.h"
1.16 +#include "nsITimer.h"
1.17 +#include "nsIMemoryReporter.h"
1.18 +#include "nsIObserverService.h"
1.19 +#include "nsIObserver.h"
1.20 +#include "nsIOutputStream.h"
1.21 +#include "nsIFile.h"
1.22 +#include "mozilla/Attributes.h"
1.23 +#include "mozilla/MemoryReporting.h"
1.24 +#include "mozilla/StaticPtr.h"
1.25 +
1.26 +/**
1.27 + * The StartupCache is a persistent cache of simple key-value pairs,
1.28 + * where the keys are null-terminated c-strings and the values are
1.29 + * arbitrary data, passed as a (char*, size) tuple.
1.30 + *
1.31 + * Clients should use the GetSingleton() static method to access the cache. It
1.32 + * will be available from the end of XPCOM init (NS_InitXPCOM3 in nsXPComInit.cpp),
1.33 + * until XPCOM shutdown begins. The GetSingleton() method will return null if the cache
1.34 + * is unavailable. The cache is only provided for libxul builds --
1.35 + * it will fail to link in non-libxul builds. The XPCOM interface is provided
1.36 + * only to allow compiled-code tests; clients should avoid using it.
1.37 + *
1.38 + * The API provided is very simple: GetBuffer() returns a buffer that was previously
1.39 + * stored in the cache (if any), and PutBuffer() inserts a buffer into the cache.
1.40 + * GetBuffer returns a new buffer, and the caller must take ownership of it.
1.41 + * PutBuffer will assert if the client attempts to insert a buffer with the same name as
1.42 + * an existing entry. The cache makes a copy of the passed-in buffer, so client
1.43 + * retains ownership.
1.44 + *
1.45 + * InvalidateCache() may be called if a client suspects data corruption
1.46 + * or wishes to invalidate for any other reason. This will remove all existing cache data.
1.47 + * Additionally, the static method IgnoreDiskCache() can be called if it is
1.48 + * believed that the on-disk cache file is itself corrupt. This call implicitly
1.49 + * calls InvalidateCache (if the singleton has been initialized) to ensure any
1.50 + * data already read from disk is discarded. The cache will not load data from
1.51 + * the disk file until a successful write occurs.
1.52 + *
1.53 + * Finally, getDebugObjectOutputStream() allows debug code to wrap an objectstream
1.54 + * with a debug objectstream, to check for multiply-referenced objects. These will
1.55 + * generally fail to deserialize correctly, unless they are stateless singletons or the
1.56 + * client maintains their own object data map for deserialization.
1.57 + *
1.58 + * Writes before the final-ui-startup notification are placed in an intermediate
1.59 + * cache in memory, then written out to disk at a later time, to get writes off the
1.60 + * startup path. In any case, clients should not rely on being able to GetBuffer()
1.61 + * data that is written to the cache, since it may not have been written to disk or
1.62 + * another client may have invalidated the cache. In other words, it should be used as
1.63 + * a cache only, and not a reliable persistent store.
1.64 + *
1.65 + * Some utility functions are provided in StartupCacheUtils. These functions wrap the
1.66 + * buffers into object streams, which may be useful for serializing objects. Note
1.67 + * the above caution about multiply-referenced objects, though -- the streams are just
1.68 + * as 'dumb' as the underlying buffers about multiply-referenced objects. They just
1.69 + * provide some convenience in writing out data.
1.70 + */
1.71 +
1.72 +namespace mozilla {
1.73 +
1.74 +namespace scache {
1.75 +
1.76 +struct CacheEntry
1.77 +{
1.78 + nsAutoArrayPtr<char> data;
1.79 + uint32_t size;
1.80 +
1.81 + CacheEntry() : data(nullptr), size(0) { }
1.82 +
1.83 + // Takes possession of buf
1.84 + CacheEntry(char* buf, uint32_t len) : data(buf), size(len) { }
1.85 +
1.86 + ~CacheEntry()
1.87 + {
1.88 + }
1.89 +
1.90 + size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) {
1.91 + return mallocSizeOf(data);
1.92 + }
1.93 +};
1.94 +
1.95 +// We don't want to refcount StartupCache, and ObserverService wants to
1.96 +// refcount its listeners, so we'll let it refcount this instead.
1.97 +class StartupCacheListener MOZ_FINAL : public nsIObserver
1.98 +{
1.99 + NS_DECL_THREADSAFE_ISUPPORTS
1.100 + NS_DECL_NSIOBSERVER
1.101 +};
1.102 +
1.103 +class StartupCache : public nsIMemoryReporter
1.104 +{
1.105 +
1.106 +friend class StartupCacheListener;
1.107 +friend class StartupCacheWrapper;
1.108 +
1.109 +public:
1.110 + NS_DECL_THREADSAFE_ISUPPORTS
1.111 + NS_DECL_NSIMEMORYREPORTER
1.112 +
1.113 + // StartupCache methods. See above comments for a more detailed description.
1.114 +
1.115 + // Returns a buffer that was previously stored, caller takes ownership.
1.116 + nsresult GetBuffer(const char* id, char** outbuf, uint32_t* length);
1.117 +
1.118 + // Stores a buffer. Caller keeps ownership, we make a copy.
1.119 + nsresult PutBuffer(const char* id, const char* inbuf, uint32_t length);
1.120 +
1.121 + // Removes the cache file.
1.122 + void InvalidateCache();
1.123 +
1.124 + // Signal that data should not be loaded from the cache file
1.125 + static void IgnoreDiskCache();
1.126 +
1.127 + // In DEBUG builds, returns a stream that will attempt to check for
1.128 + // and disallow multiple writes of the same object.
1.129 + nsresult GetDebugObjectOutputStream(nsIObjectOutputStream* aStream,
1.130 + nsIObjectOutputStream** outStream);
1.131 +
1.132 + nsresult RecordAgesAlways();
1.133 +
1.134 + static StartupCache* GetSingleton();
1.135 + static void DeleteSingleton();
1.136 +
1.137 + // This measures all the heap memory used by the StartupCache, i.e. it
1.138 + // excludes the mapping.
1.139 + size_t HeapSizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf);
1.140 +
1.141 + size_t SizeOfMapping();
1.142 +
1.143 +private:
1.144 + StartupCache();
1.145 + virtual ~StartupCache();
1.146 +
1.147 + enum TelemetrifyAge {
1.148 + IGNORE_AGE = 0,
1.149 + RECORD_AGE = 1
1.150 + };
1.151 + static enum TelemetrifyAge gPostFlushAgeAction;
1.152 +
1.153 + nsresult LoadArchive(enum TelemetrifyAge flag);
1.154 + nsresult Init();
1.155 + void WriteToDisk();
1.156 + nsresult ResetStartupWriteTimer();
1.157 + void WaitOnWriteThread();
1.158 +
1.159 + static nsresult InitSingleton();
1.160 + static void WriteTimeout(nsITimer *aTimer, void *aClosure);
1.161 + static void ThreadedWrite(void *aClosure);
1.162 +
1.163 + static size_t SizeOfEntryExcludingThis(const nsACString& key,
1.164 + const nsAutoPtr<CacheEntry>& data,
1.165 + mozilla::MallocSizeOf mallocSizeOf,
1.166 + void *);
1.167 +
1.168 + nsClassHashtable<nsCStringHashKey, CacheEntry> mTable;
1.169 + nsRefPtr<nsZipArchive> mArchive;
1.170 + nsCOMPtr<nsIFile> mFile;
1.171 +
1.172 + nsCOMPtr<nsIObserverService> mObserverService;
1.173 + nsRefPtr<StartupCacheListener> mListener;
1.174 + nsCOMPtr<nsITimer> mTimer;
1.175 +
1.176 + bool mStartupWriteInitiated;
1.177 +
1.178 + static StaticRefPtr<StartupCache> gStartupCache;
1.179 + static bool gShutdownInitiated;
1.180 + static bool gIgnoreDiskCache;
1.181 + PRThread *mWriteThread;
1.182 +#ifdef DEBUG
1.183 + nsTHashtable<nsISupportsHashKey> mWriteObjectMap;
1.184 +#endif
1.185 +};
1.186 +
1.187 +// This debug outputstream attempts to detect if clients are writing multiple
1.188 +// references to the same object. We only support that if that object
1.189 +// is a singleton.
1.190 +#ifdef DEBUG
1.191 +class StartupCacheDebugOutputStream MOZ_FINAL
1.192 + : public nsIObjectOutputStream
1.193 +{
1.194 + NS_DECL_ISUPPORTS
1.195 + NS_DECL_NSIOBJECTOUTPUTSTREAM
1.196 +
1.197 + StartupCacheDebugOutputStream (nsIObjectOutputStream* binaryStream,
1.198 + nsTHashtable<nsISupportsHashKey>* objectMap)
1.199 + : mBinaryStream(binaryStream), mObjectMap(objectMap) { }
1.200 +
1.201 + NS_FORWARD_SAFE_NSIBINARYOUTPUTSTREAM(mBinaryStream)
1.202 + NS_FORWARD_SAFE_NSIOUTPUTSTREAM(mBinaryStream)
1.203 +
1.204 + bool CheckReferences(nsISupports* aObject);
1.205 +
1.206 + nsCOMPtr<nsIObjectOutputStream> mBinaryStream;
1.207 + nsTHashtable<nsISupportsHashKey> *mObjectMap;
1.208 +};
1.209 +#endif // DEBUG
1.210 +
1.211 +// XPCOM wrapper interface provided for tests only.
1.212 +#define NS_STARTUPCACHE_CID \
1.213 + {0xae4505a9, 0x87ab, 0x477c, \
1.214 + {0xb5, 0x77, 0xf9, 0x23, 0x57, 0xed, 0xa8, 0x84}}
1.215 +// contract id: "@mozilla.org/startupcache/cache;1"
1.216 +
1.217 +class StartupCacheWrapper MOZ_FINAL
1.218 + : public nsIStartupCache
1.219 +{
1.220 + NS_DECL_THREADSAFE_ISUPPORTS
1.221 + NS_DECL_NSISTARTUPCACHE
1.222 +
1.223 + static StartupCacheWrapper* GetSingleton();
1.224 + static StartupCacheWrapper *gStartupCacheWrapper;
1.225 +};
1.226 +
1.227 +} // namespace scache
1.228 +} // namespace mozilla
1.229 +#endif //StartupCache_h_
