gecko/xpcom/components/nsCategoryManager.h

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#ifndef NSCATEGORYMANAGER_H
#define NSCATEGORYMANAGER_H

#include "prio.h"
#include "plarena.h"
#include "nsClassHashtable.h"
#include "nsICategoryManager.h"
#include "mozilla/Mutex.h"

#define NS_CATEGORYMANAGER_CLASSNAME     "Category Manager"

/* 16d222a6-1dd2-11b2-b693-f38b02c021b2 */
#define NS_CATEGORYMANAGER_CID \
{ 0x16d222a6, 0x1dd2, 0x11b2, \
  {0xb6, 0x93, 0xf3, 0x8b, 0x02, 0xc0, 0x21, 0xb2} }

/**
 * a "leaf-node", managed by the nsCategoryNode hashtable.
 *
 * we need to keep a "persistent value" (which will be written to the registry)
 * and a non-persistent value (for the current runtime): these are usually
 * the same, except when aPersist==PR_FALSE. The strings are permanently arena-
 * allocated, and will never go away.
 */
class CategoryLeaf : public nsDepCharHashKey
{
public:
  CategoryLeaf(const char* aKey)
    : nsDepCharHashKey(aKey),
      pValue(nsnull),
      nonpValue(nsnull) { }
  const char* pValue;
  const char* nonpValue;
};


/**
 * CategoryNode keeps a hashtable of its entries.
 * the CategoryNode itself is permanently allocated in
 * the arena.
 */
class CategoryNode
{
public:
  NS_METHOD GetLeaf(const char* aEntryName,
                    char** _retval);

  NS_METHOD AddLeaf(const char* aEntryName,
                    const char* aValue,
                    PRBool aPersist,
                    PRBool aReplace,
                    char** _retval,
                    PLArenaPool* aArena);

  NS_METHOD DeleteLeaf(const char* aEntryName,
                       PRBool aDontPersist);

  void Clear() {
    mozilla::MutexAutoLock lock(mLock);
    mTable.Clear();
  }

  PRUint32 Count() {
    mozilla::MutexAutoLock lock(mLock);
    PRUint32 tCount = mTable.Count();
    return tCount;
  }

  NS_METHOD Enumerate(nsISimpleEnumerator** _retval);

  PRBool WritePersistentEntries(PRFileDesc* fd, const char* aCategoryName);

  // CategoryNode is arena-allocated, with the strings
  static CategoryNode* Create(PLArenaPool* aArena);
  ~CategoryNode();
  void operator delete(void*) { }

private:
  CategoryNode()
    : mLock("CategoryLeaf")
  { }

  void* operator new(size_t aSize, PLArenaPool* aArena);

  nsTHashtable<CategoryLeaf> mTable;
  mozilla::Mutex mLock;
};


/**
 * The main implementation of nsICategoryManager.
 *
 * This implementation is thread-safe.
 */
class nsCategoryManager
  : public nsICategoryManager
{
public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSICATEGORYMANAGER

  /**
   * Write the categories to the XPCOM persistent registry.
   * This is to be used by nsComponentManagerImpl (and NO ONE ELSE).
   */
  NS_METHOD WriteCategoryManagerToRegistry(PRFileDesc* fd);

  /**
   * Suppress or unsuppress notifications of category changes to the
   * observer service. This is to be used by nsComponentManagerImpl
   * on startup while reading the stored category list.
   */
  NS_METHOD SuppressNotifications(PRBool aSuppress);

  nsCategoryManager()
    : mLock("nsCategoryManager")
    , mSuppressNotifications(PR_FALSE)
  { }

private:
  friend class nsCategoryManagerFactory;
  static nsCategoryManager* Create();

  ~nsCategoryManager();

  CategoryNode* get_category(const char* aName);
  void NotifyObservers(const char* aTopic,
                       const char* aCategoryName,
                       const char* aEntryName);

  PLArenaPool mArena;
  nsClassHashtable<nsDepCharHashKey, CategoryNode> mTable;
  mozilla::Mutex mLock;
  PRBool mSuppressNotifications;
};

#endif