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diff --git a/startupcache/StartupCache.h b/startupcache/StartupCache.h
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+++ b/startupcache/StartupCache.h
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+/* -*-  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_