gecko-dev/xpcom/ds/nsISizeOfHandler.h

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#ifndef nsISizeOfHandler_h___
#define nsISizeOfHandler_h___

#include "nscore.h"
#include "nsISupports.h"

/* c028d1f0-fc9e-11d1-89e4-006008911b81 */
#define NS_ISIZEOF_HANDLER_IID \
{ 0xc028d1f0, 0xfc9e, 0x11d1, {0x89, 0xe4, 0x00, 0x60, 0x08, 0x91, 0x1b, 0x81}}

class nsIAtom;
class nsISizeOfHandler;

/**
 * Function used by the Report method to report data gathered during
 * a collection of data.
 */
typedef void (*nsISizeofReportFunc)(nsISizeOfHandler* aHandler,
                                    nsIAtom* aKey,
                                    PRUint32 aCount,
                                    PRUint32 aTotalSize,
                                    PRUint32 aMinSize,
                                    PRUint32 aMaxSize,
                                    void* aArg);

/**
 * An API to managing a sizeof computation of an arbitrary graph.
 * The handler is responsible for remembering which objects have been
 * seen before (using RecordObject). Note that the handler doesn't
 * hold references to nsISupport's objects; the assumption is that the
 * objects being sized are stationary and will not be modified during
 * the sizing computation and therefore do not need an extra reference
 * count.
 *
 * Users of this API are responsible for the actual graph/tree walking.
 */
class nsISizeOfHandler : public nsISupports {
public:
	NS_DEFINE_STATIC_IID_ACCESSOR(NS_ISIZEOF_HANDLER_IID)

  /**
   * Initialize the handler for a new collection of data. This empties
   * out the object prescence table and the keyed size table.
   */
  NS_IMETHOD Init() = 0;

  /**
   * Record the sizing status of a given object. The first time
   * aObject is recorded, aResult will be PR_FALSE. Subsequent times,
   * aResult will be PR_TRUE.
   */
  NS_IMETHOD RecordObject(void* aObject, PRBool* aResult) = 0;

  /**
   * Add size information to the running size data. The atom is used
   * as a key to keep type specific running totals of size
   * information.  This increments the total count and the total size
   * as well as updates the minimum, maximum and total size for aKey's
   * type.
   */
  NS_IMETHOD AddSize(nsIAtom* aKey, PRUint32 aSize) = 0;

  /**
   * Enumerate data collected for each type and invoke the
   * reporting function with the data gathered.
   */
  NS_IMETHOD Report(nsISizeofReportFunc aFunc, void* aArg) = 0;

  /**
   * Get the current totals - the number of total objects sized (not
   * necessarily anything to do with RecordObject's tracking of
   * objects) and the total number of bytes that those object use. The
   * counters are not reset by this call (use Init to reset
   * everything).
   */
  NS_IMETHOD GetTotals(PRUint32* aTotalCountResult,
                       PRUint32* aTotalSizeResult) = 0;
};

extern NS_COM nsresult
NS_NewSizeOfHandler(nsISizeOfHandler** aInstancePtrResult);

#endif /* nsISizeofHandler_h___ */