gecko-dev/xpcom/base/nsIMemoryReporter.idl

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

#include "nsISupports.idl"

interface nsICancelableRunnable;
interface nsIDOMWindow;
interface nsIRunnable;
interface nsISimpleEnumerator;

/*
 * Memory reporters measure Firefox's memory usage.  They are primarily used to
 * generate the about:memory page.  You should read
 * https://wiki.mozilla.org/Memory_Reporting before writing a memory
 * reporter.
 */

[scriptable, function, uuid(3a61be3b-b93b-461a-a4f8-388214f558b1)]
interface nsIMemoryReporterCallback : nsISupports
{
  /*
   * The arguments to the callback are as follows.
   *
   *
   * |process|  The name of the process containing this reporter.  Each
   * reporter initially has "" in this field, indicating that it applies to the
   * current process.  (This is true even for reporters in a child process.)
   * When a reporter from a child process is copied into the main process, the
   * copy has its 'process' field set appropriately.
   *
   *
   * |path|  The path that this memory usage should be reported under.  Paths
   * are '/'-delimited, eg. "a/b/c".
   *
   * Each reporter can be viewed as representing a leaf node in a tree.
   * Internal nodes of the tree don't have reporters.  So, for example, the
   * reporters "explicit/a/b", "explicit/a/c", "explicit/d/e", and
   * "explicit/d/f" define this tree:
   *
   *   explicit
   *   |--a
   *   |  |--b [*]
   *   |  \--c [*]
   *   \--d
   *      |--e [*]
   *      \--f [*]
   *
   * Nodes marked with a [*] have a reporter.  Notice that the internal
   * nodes are implicitly defined by the paths.
   *
   * Nodes within a tree should not overlap measurements, otherwise the
   * parent node measurements will be double-counted.  So in the example
   * above, |b| should not count any allocations counted by |c|, and vice
   * versa.
   *
   * All nodes within each tree must have the same units.
   *
   * If you want to include a '/' not as a path separator, e.g. because the
   * path contains a URL, you need to convert each '/' in the URL to a '\'.
   * Consumers of the path will undo this change.  Any other '\' character
   * in a path will also be changed.  This is clumsy but hasn't caused any
   * problems so far.
   *
   * The paths of all reporters form a set of trees.  Trees can be
   * "degenerate", i.e. contain a single entry with no '/'.
   *
   *
   * |kind|  There are three kinds of memory reporters.
   *
   *  - HEAP: reporters measuring memory allocated by the heap allocator,
   *    e.g. by calling malloc, calloc, realloc, memalign, operator new, or
   *    operator new[].  Reporters in this category must have units
   *    UNITS_BYTES.
   *
   *  - NONHEAP: reporters measuring memory which the program explicitly
   *    allocated, but does not live on the heap.  Such memory is commonly
   *    allocated by calling one of the OS's memory-mapping functions (e.g.
   *    mmap, VirtualAlloc, or vm_allocate).  Reporters in this category
   *    must have units UNITS_BYTES.
   *
   *  - OTHER: reporters which don't fit into either of these categories.
   *    They can have any units.
   *
   * The kind only matters for reporters in the "explicit" tree;
   * aboutMemory.js uses it to calculate "heap-unclassified".
   *
   *
   * |units|  The units on the reporter's amount.  One of the following.
   *
   *  - BYTES: The amount contains a number of bytes.
   *
   *  - COUNT: The amount is an instantaneous count of things currently in
   *    existence.  For instance, the number of tabs currently open would have
   *    units COUNT.
   *
   *  - COUNT_CUMULATIVE: The amount contains the number of times some event
   *    has occurred since the application started up.  For instance, the
   *    number of times the user has opened a new tab would have units
   *    COUNT_CUMULATIVE.
   *
   *    The amount returned by a reporter with units COUNT_CUMULATIVE must
   *    never decrease over the lifetime of the application.
   *
   *  - PERCENTAGE: The amount contains a fraction that should be expressed as
   *    a percentage.  NOTE!  The |amount| field should be given a value 100x
   *    the actual percentage;  this number will be divided by 100 when shown.
   *    This allows a fractional percentage to be shown even though |amount| is
   *    an integer.  E.g. if the actual percentage is 12.34%, |amount| should
   *    be 1234.
   *
   *    Values greater than 100% are allowed.
   *
   *
   * |amount|  The numeric value reported by this memory reporter.  Accesses
   * can fail if something goes wrong when getting the amount.
   *
   *
   * |description|  A human-readable description of this memory usage report.
   */
  void callback(in ACString process, in AUTF8String path, in int32_t kind,
                in int32_t units, in int64_t amount,
                in AUTF8String description, in nsISupports closure);
};

/*
 * An nsIMemoryReporter reports one or more memory measurements via a
 * callback function which is called once for each measurement.
 *
 * An nsIMemoryReporter that reports a single measurement is sometimes called a
 * "uni-reporter".  One that reports multiple measurements is sometimes called
 * a "multi-reporter".
 *
 * aboutMemory.js is the most important consumer of memory reports.  It
 * places the following constraints on reports.
 *
 * - There must be an "explicit" tree.  It represents non-overlapping
 *   regions of memory that have been explicitly allocated with an
 *   OS-level allocation (e.g. mmap/VirtualAlloc/vm_allocate) or a
 *   heap-level allocation (e.g. malloc/calloc/operator new).  Reporters
 *   in this tree must have kind HEAP or NONHEAP, units BYTES, and a
 *   description that is a sentence (i.e. starts with a capital letter and
 *   ends with a period, or similar).
 *
 * - All other reports are unconstrained except that they must have a
 *   description that is a sentence.
 */
[scriptable, uuid(53248304-124b-43cd-99dc-6e5797b91618)]
interface nsIMemoryReporter : nsISupports
{
  /*
   * The name of the reporter.  Useful when only one reporter needs to be run.
   * Must be unique;  if reporters share names it's likely the wrong one will
   * be called in certain circumstances.
   */
  readonly attribute ACString name;

  /*
   * Run the reporter.
   */
  void collectReports(in nsIMemoryReporterCallback callback,
                      in nsISupports closure);

  /*
   * Kinds.  See the |kind| comment in nsIMemoryReporterCallback.
   */
  const int32_t KIND_NONHEAP = 0;
  const int32_t KIND_HEAP    = 1;
  const int32_t KIND_OTHER   = 2;

  /*
   * Units.  See the |units| comment in nsIMemoryReporterCallback.
   */
  const int32_t UNITS_BYTES = 0;
  const int32_t UNITS_COUNT = 1;
  const int32_t UNITS_COUNT_CUMULATIVE = 2;
  const int32_t UNITS_PERCENTAGE = 3;
};

[scriptable, builtinclass, uuid(4db7040a-16f9-4249-879b-fe72729c7ef5)]
interface nsIMemoryReporterManager : nsISupports
{
  /*
   * Return an enumerator of nsIMemoryReporters that are currently registered.
   */
  nsISimpleEnumerator enumerateReporters();

  /*
   * Register the given nsIMemoryReporter.  After a reporter is registered,
   * it will be available via enumerateReporters().  The Manager service
   * will hold a strong reference to the given reporter.
   */
  void registerReporter(in nsIMemoryReporter reporter);

  /*
   * Unregister the given memory reporter.
   */
  void unregisterReporter(in nsIMemoryReporter reporter);

  /*
   * These functions should only be used for testing purposes.
   */
  void blockRegistration();
  void unblockRegistration();
  void registerReporterEvenIfBlocked(in nsIMemoryReporter aReporter);

  /*
   * Initialize.
   */
  void init();

  /*
   * The memory reporter manager, for the most part, treats reporters
   * registered with it as a black box.  However, there are some
   * "distinguished" amounts (as could be reported by a memory reporter) that
   * the manager provides as attributes, because they are sufficiently
   * interesting that we want external code (e.g. telemetry) to be able to rely
   * on them.
   *
   * Note that these are not reporters and so enumerateReporters() does not
   * look at them.  However, they can be embedded in a reporter.
   *
   * Access to these attributes can fail.  In particular, some of them are not
   * available on all platforms.
   *
   * If you add a new distinguished amount, please update
   * toolkit/components/aboutmemory/tests/test_memoryReporters.xul.
   *
   * |explicit| (UNITS_BYTES)  The total size of explicit memory allocations,
   * both at the OS-level (eg. via mmap, VirtualAlloc) and at the heap level
   * (eg. via malloc, calloc, operator new).  It covers all heap allocations,
   * but will miss any OS-level ones not covered by memory reporters.
   *
   * |vsize| (UNITS_BYTES)  The virtual size, i.e. the amount of address space
   * taken up.
   *
   * |resident| (UNITS_BYTES)  The resident size (a.k.a. RSS or physical memory
   * used).
   *
   * |residentFast| (UNITS_BYTES)  This is like |resident|, but on Mac OS
   * |resident| can purge pages, which is slow.  It also affects the result of
   * |residentFast|, and so |resident| and |residentFast| should not be used
   * together.
   *
   * |heapAllocated| (UNITS_BYTES)  Memory mapped by the heap allocator.
   *
   * |heapOverheadRatio| (UNITS_PERCENTAGE)  In the heap allocator, this is the
   * ratio of committed, unused bytes to allocated bytes.  Like all
   * UNITS_PERCENTAGE measurements, its amount is multiplied by 100x so it can
   * be represented by an int64_t.
   *
   * |JSMainRuntimeGCHeap| (UNITS_BYTES)  Size of the main JS runtime's GC
   * heap.
   *
   * |JSMainRuntimeTemporaryPeak| (UNITS_BYTES)  Peak size of the transient
   * storage in the main JSRuntime.
   *
   * |JSMainRuntimeCompartments{System,User}| (UNITS_COUNT)  The number of
   * {system,user} compartments in the main JS runtime.
   *
   * |imagesContentUsedUncompressed| (UNITS_BYTES)  Memory used for decoded
   * images in content.
   *
   * |storageSQLite| (UNITS_BYTES)  Memory used by SQLite.
   *
   * |lowMemoryEvents{Virtual,Physical}| (UNITS_COUNT_CUMULATIVE)  The number
   * of low-{virtual,physical}-memory events that have occurred since the
   * process started.
   *
   * |ghostWindows| (UNITS_COUNT)  The number of ghost windows.
   *
   * |pageFaultsHard| (UNITS_COUNT_CUMULATIVE)  The number of hard (a.k.a.
   * major) page faults that have occurred since the process started.
   */
  readonly attribute int64_t explicit;
  readonly attribute int64_t vsize;
  readonly attribute int64_t resident;
  readonly attribute int64_t residentFast;

  readonly attribute int64_t heapAllocated;
  readonly attribute int64_t heapOverheadRatio;

  readonly attribute int64_t JSMainRuntimeGCHeap;
  readonly attribute int64_t JSMainRuntimeTemporaryPeak;
  readonly attribute int64_t JSMainRuntimeCompartmentsSystem;
  readonly attribute int64_t JSMainRuntimeCompartmentsUser;

  readonly attribute int64_t imagesContentUsedUncompressed;

  readonly attribute int64_t storageSQLite;

  readonly attribute int64_t lowMemoryEventsVirtual;
  readonly attribute int64_t lowMemoryEventsPhysical;

  readonly attribute int64_t ghostWindows;

  readonly attribute int64_t pageFaultsHard;

  /*
   * This attribute indicates if moz_malloc_usable_size() works.
   */
  [infallible] readonly attribute boolean hasMozMallocUsableSize;

  /*
   * Run a series of GC/CC's in an attempt to minimize the application's memory
   * usage.  When we're finished, we invoke the given runnable if it's not
   * null.  Returns a reference to the runnable used for carrying out the task.
   */
  nsICancelableRunnable minimizeMemoryUsage(in nsIRunnable callback);

  /*
   * Measure the memory that is known to be owned by this tab, split up into
   * several broad categories.  Note that this will be an underestimate of the
   * true number, due to imperfect memory reporter coverage (corresponding to
   * about:memory's "heap-unclassified"), and due to some memory shared between
   * tabs not being counted.
   *
   * The time taken for the measurement (split into JS and non-JS parts) is
   * also returned.
   */
  void sizeOfTab(in nsIDOMWindow window,
                 out int64_t jsObjectsSize, out int64_t jsStringsSize,
                 out int64_t jsOtherSize, out int64_t domSize,
                 out int64_t styleSize, out int64_t otherSize,
                 out int64_t totalSize,
                 out double jsMilliseconds, out double nonJSMilliseconds);
};

%{C++

#include "js/TypeDecls.h"
#include "nsStringGlue.h"

class nsPIDOMWindow;

// Note that the memory reporters are held in an nsCOMArray, which means
// that individual reporters should be referenced with |nsIMemoryReporter *|
// instead of nsCOMPtr<nsIMemoryReporter>.

XPCOM_API(nsresult) NS_RegisterMemoryReporter(nsIMemoryReporter* aReporter);
XPCOM_API(nsresult) NS_UnregisterMemoryReporter(nsIMemoryReporter* aReporter);

namespace mozilla {

// The memory reporter manager provides access to several distinguished
// amounts via attributes.  Some of these amounts are provided by Gecko
// components that cannot be accessed directly from XPCOM code.  So we provide
// the following functions for those components to be registered with the
// manager.

typedef int64_t (*InfallibleAmountFn)();
typedef nsresult (*FallibleAmountFn)(int64_t* aAmount);

#define DECL_REGISTER_DISTINGUISHED_AMOUNT(kind, name) \
    nsresult Register##name##DistinguishedAmount(kind##AmountFn aAmountFn);
#define DECL_UNREGISTER_DISTINGUISHED_AMOUNT(name) \
    nsresult Unregister##name##DistinguishedAmount();

DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, JSMainRuntimeGCHeap)
DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, JSMainRuntimeTemporaryPeak)
DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, JSMainRuntimeCompartmentsSystem)
DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, JSMainRuntimeCompartmentsUser)

DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, ImagesContentUsedUncompressed)

DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, StorageSQLite)
DECL_UNREGISTER_DISTINGUISHED_AMOUNT(StorageSQLite)

DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, LowMemoryEventsVirtual)
DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, LowMemoryEventsPhysical)

DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, GhostWindows)

#undef DECL_REGISTER_DISTINGUISHED_AMOUNT
#undef DECL_UNREGISTER_DISTINGUISHED_AMOUNT

// Likewise for per-tab measurement.

typedef nsresult (*JSSizeOfTabFn)(JSObject* aObj,
                                  size_t* aJsObjectsSize,
                                  size_t* aJsStringSize,
                                  size_t* aJsPrivateSize,
                                  size_t* aJsOtherSize);
typedef nsresult (*NonJSSizeOfTabFn)(nsPIDOMWindow* aWindow,
                                     size_t* aDomSize,
                                     size_t* aStyleSize,
                                     size_t* aOtherSize);

nsresult RegisterJSSizeOfTab(JSSizeOfTabFn aSizeOfTabFn);
nsresult RegisterNonJSSizeOfTab(NonJSSizeOfTabFn aSizeOfTabFn);

}

#if defined(MOZ_DMD)
namespace mozilla {
namespace dmd {
// This runs all the memory reporters but does nothing with the results;  i.e.
// it does the minimal amount of work possible for DMD to do its thing.
void RunReporters();
}
}

#if !defined(MOZ_MEMORY)
#error "MOZ_DMD requires MOZ_MEMORY"
#endif

#include "DMD.h"

#define MOZ_REPORT(ptr)          mozilla::dmd::Report(ptr)
#define MOZ_REPORT_ON_ALLOC(ptr) mozilla::dmd::ReportOnAlloc(ptr)

#else

#define MOZ_REPORT(ptr)
#define MOZ_REPORT_ON_ALLOC(ptr)

#endif  // defined(MOZ_DMD)

// Functions generated via this macro should be used by all traversal-based
// memory reporters.  Such functions return |moz_malloc_size_of(ptr)|;  this
// will always be zero on some obscure platforms.
//
// You might be wondering why we have a macro that creates multiple functions
// that differ only in their name, instead of a single
// MemoryReporterMallocSizeOf function.  It's mostly to help with DMD
// integration, though it sometimes also helps with debugging and temporary ad
// hoc profiling.  The function name chosen doesn't matter greatly, but it's
// best to make it similar to the path used by the relevant memory
// reporter(s).
#define NS_MEMORY_REPORTER_MALLOC_SIZEOF_FUN(fn)                              \
  static size_t fn(const void* aPtr)                                          \
  {                                                                           \
      MOZ_REPORT(aPtr);                                                       \
      return moz_malloc_size_of(aPtr);                                        \
  }

// Functions generated by the next two macros should be used by wrapping
// allocators that report heap blocks as soon as they are allocated and
// unreport them as soon as they are freed.  Such allocators are used in cases
// where we have third-party code that we cannot modify.  The two functions
// must always be used in tandem.
#define NS_MEMORY_REPORTER_MALLOC_SIZEOF_ON_ALLOC_FUN(fn)                     \
  static size_t fn(const void* aPtr)                                          \
  {                                                                           \
      MOZ_REPORT_ON_ALLOC(aPtr);                                              \
      return moz_malloc_size_of(aPtr);                                        \
  }
#define NS_MEMORY_REPORTER_MALLOC_SIZEOF_ON_FREE_FUN(fn)                      \
  static size_t fn(const void* aPtr)                                          \
  {                                                                           \
      return moz_malloc_size_of(aPtr);                                        \
  }

namespace mozilla {

// The following base class reduces the amount of boilerplate code required for
// memory uni-reporters.  You just need to provide the following.
// - The constant values: nameAndPath (which serves as both the reporters name,
//   and the path in its single report), kind, units, and description.  They
//   are passed to the MemoryUniReporter constructor.
// - A (private) Amount() or (public) GetAmount() method.  It can use the
//   MallocSizeOf method if necessary.  (There is also
//   MallocSizeOfOn{Alloc,Free}, which can be useful.)  Use Amount() if the
//   reporter is infallible, and GetAmount() otherwise.  (If you fail to
//   provide one or the other, you'll get assertion failures when the memory
//   reporter runs.)
//
// The class name of subclasses should match the path, minus the "explicit"
// (if present), and with "Reporter" at the end.  For example:
// - "explicit/dom/xyzzy"     --> DOMXyzzyReporter
// - "js-compartments/system" --> JSCompartmentsSystemReporter
//
class MemoryUniReporter : public nsIMemoryReporter
{
public:
  MemoryUniReporter(const char* aNameAndPath, int32_t aKind, int32_t aUnits,
                    const char* aDescription)
    : mNameAndPath(aNameAndPath)
    , mKind(aKind)
    , mUnits(aUnits)
    , mDescription(aDescription)
  {}

  virtual ~MemoryUniReporter() {}

  NS_DECL_THREADSAFE_ISUPPORTS

  NS_IMETHOD GetName(nsACString& aName)
  {
    aName.Assign(mNameAndPath);
    return NS_OK;
  }

  NS_IMETHOD CollectReports(nsIMemoryReporterCallback* aCallback,
                            nsISupports* aClosure)
  {
    int64_t amount;
    nsresult rv = GetAmount(&amount);
    NS_ENSURE_SUCCESS(rv, rv);

    return aCallback->Callback(EmptyCString(), mNameAndPath, mKind, mUnits,
                               amount, mDescription, aClosure);
  }

protected:
  NS_IMETHOD GetAmount(int64_t* aAmount)
  {
    *aAmount = Amount();
    return NS_OK;
  }

  virtual int64_t Amount()
  {
    // We only reach here if neither GetAmount() nor Amount() was overridden.
    MOZ_ASSERT(false);
    return 0;
  }

  NS_MEMORY_REPORTER_MALLOC_SIZEOF_FUN(MallocSizeOf)
  NS_MEMORY_REPORTER_MALLOC_SIZEOF_ON_ALLOC_FUN(MallocSizeOfOnAlloc)
  NS_MEMORY_REPORTER_MALLOC_SIZEOF_ON_FREE_FUN(MallocSizeOfOnFree)

  const nsCString mNameAndPath;
  const int32_t   mKind;
  const int32_t   mUnits;
  const nsCString mDescription;
};

} // namespace mozilla

%}