gecko-dev/dom/xul/nsXULPrototypeCache.h

/* -*- Mode: C++; tab-width: 4; 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 nsXULPrototypeCache_h__
#define nsXULPrototypeCache_h__

#include "nsCOMPtr.h"
#include "nsIObserver.h"
#include "nsJSThingHashtable.h"
#include "nsInterfaceHashtable.h"
#include "nsRefPtrHashtable.h"
#include "nsURIHashKey.h"
#include "nsXULPrototypeDocument.h"
#include "nsIStorageStream.h"

#include "mozilla/scache/StartupCache.h"

class nsIHandleReportCallback;
namespace mozilla {
class StyleSheet;
}  // namespace mozilla

/**
 * The XUL prototype cache can be used to store and retrieve shared data for
 * XUL documents, style sheets, XBL, and scripts.
 *
 * The cache has two levels:
 *  1. In-memory hashtables
 *  2. The on-disk cache file.
 */
class nsXULPrototypeCache : public nsIObserver {
 public:
  // nsISupports
  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSIOBSERVER

  bool IsCached(nsIURI* aURI) { return GetPrototype(aURI) != nullptr; }
  void AbortCaching();

  /**
   * Whether the prototype cache is enabled.
   */
  bool IsEnabled();

  /**
   * Flush the cache; remove all XUL prototype documents, style
   * sheets, and scripts.
   */
  void Flush();

  // The following methods are used to put and retrive various items into and
  // from the cache.

  nsXULPrototypeDocument* GetPrototype(nsIURI* aURI);
  nsresult PutPrototype(nsXULPrototypeDocument* aDocument);

  JSScript* GetScript(nsIURI* aURI);
  nsresult PutScript(nsIURI* aURI, JS::Handle<JSScript*> aScriptObject);

  /**
   * Get a style sheet by URI. If the style sheet is not in the cache,
   * returns nullptr.
   */
  mozilla::StyleSheet* GetStyleSheet(nsIURI* aURI);

  /**
   * Store a style sheet in the cache. The key, style sheet's URI is obtained
   * from the style sheet itself.
   */
  nsresult PutStyleSheet(mozilla::StyleSheet* aStyleSheet);

  /**
   * Write the XUL prototype document to a cache file. The proto must be
   * fully loaded.
   */
  nsresult WritePrototype(nsXULPrototypeDocument* aPrototypeDocument);

  /**
   * This interface allows partial reads and writes from the buffers in the
   * startupCache.
   */
  nsresult GetInputStream(nsIURI* aURI, nsIObjectInputStream** objectInput);
  nsresult FinishInputStream(nsIURI* aURI);
  nsresult GetOutputStream(nsIURI* aURI, nsIObjectOutputStream** objectOutput);
  nsresult FinishOutputStream(nsIURI* aURI);
  nsresult HasData(nsIURI* aURI, bool* exists);

  static nsXULPrototypeCache* GetInstance();
  static nsXULPrototypeCache* MaybeGetInstance() { return sInstance; }

  static void ReleaseGlobals() { NS_IF_RELEASE(sInstance); }

  void MarkInCCGeneration(uint32_t aGeneration);
  void MarkInGC(JSTracer* aTrc);
  void FlushScripts();

  static void CollectMemoryReports(nsIHandleReportCallback* aHandleReport,
                                   nsISupports* aData);

 protected:
  friend nsresult NS_NewXULPrototypeCache(nsISupports* aOuter, REFNSIID aIID,
                                          void** aResult);

  nsXULPrototypeCache();
  virtual ~nsXULPrototypeCache();

  static nsXULPrototypeCache* sInstance;

  using StyleSheetTable = nsRefPtrHashtable<nsURIHashKey, mozilla::StyleSheet>;

  nsRefPtrHashtable<nsURIHashKey, nsXULPrototypeDocument>
      mPrototypeTable;  // owns the prototypes
  StyleSheetTable mStyleSheetTable;
  nsJSThingHashtable<nsURIHashKey, JSScript*> mScriptTable;

  // URIs already written to the startup cache, to prevent double-caching.
  nsTHashtable<nsURIHashKey> mStartupCacheURITable;

  nsInterfaceHashtable<nsURIHashKey, nsIStorageStream> mOutputStreamTable;
  nsInterfaceHashtable<nsURIHashKey, nsIObjectInputStream> mInputStreamTable;

  // Bootstrap caching service
  nsresult BeginCaching(nsIURI* aDocumentURI);
};

#endif  // nsXULPrototypeCache_h__