nsMemoryReporterManager.cpp

/* -*- Mode: C++; tab-width: 50; 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/. */

#include "nsAtomTable.h"
#include "nsAutoPtr.h"
#include "nsCOMPtr.h"
#include "nsDirectoryServiceUtils.h"
#include "nsServiceManagerUtils.h"
#include "nsMemoryReporterManager.h"
#include "nsArrayEnumerator.h"
#include "nsISimpleEnumerator.h"
#include "nsIFile.h"
#include "nsIFileStreams.h"
#include "nsPrintfCString.h"
#include "nsThreadUtils.h"
#include "nsIObserverService.h"
#include "nsThread.h"
#include "nsMemoryInfoDumper.h"
#include "mozilla/Telemetry.h"
#include "mozilla/Attributes.h"
#include "mozilla/Services.h"

#ifndef XP_WIN
#include <unistd.h>
#endif

using namespace mozilla;

#if defined(MOZ_MEMORY)
#  define HAVE_JEMALLOC_STATS 1
#  include "mozmemory.h"
#endif  // MOZ_MEMORY

#ifdef XP_UNIX

#include <sys/time.h>
#include <sys/resource.h>

#define HAVE_PAGE_FAULT_REPORTERS 1
static nsresult GetHardPageFaults(int64_t *n)
{
    struct rusage usage;
    int err = getrusage(RUSAGE_SELF, &usage);
    if (err != 0) {
        return NS_ERROR_FAILURE;
    }
    *n = usage.ru_majflt;
    return NS_OK;
}

static nsresult GetSoftPageFaults(int64_t *n)
{
    struct rusage usage;
    int err = getrusage(RUSAGE_SELF, &usage);
    if (err != 0) {
        return NS_ERROR_FAILURE;
    }
    *n = usage.ru_minflt;
    return NS_OK;
}

#endif  // HAVE_PAGE_FAULT_REPORTERS

#if defined(XP_LINUX)

#include <unistd.h>
static nsresult GetProcSelfStatmField(int field, int64_t *n)
{
    // There are more than two fields, but we're only interested in the first
    // two.
    static const int MAX_FIELD = 2;
    size_t fields[MAX_FIELD];
    MOZ_ASSERT(field < MAX_FIELD, "bad field number");
    FILE *f = fopen("/proc/self/statm", "r");
    if (f) {
        int nread = fscanf(f, "%zu %zu", &fields[0], &fields[1]);
        fclose(f);
        if (nread == MAX_FIELD) {
            *n = fields[field] * getpagesize();
            return NS_OK;
        } 
    }
    return NS_ERROR_FAILURE;
}

#define HAVE_VSIZE_AND_RESIDENT_REPORTERS 1
static nsresult GetVsize(int64_t *n)
{
    return GetProcSelfStatmField(0, n);
}

static nsresult GetResident(int64_t *n)
{
    return GetProcSelfStatmField(1, n);
}

#elif defined(__DragonFly__) || defined(__FreeBSD__) \
    || defined(__NetBSD__) || defined(__OpenBSD__)

#include <sys/param.h>
#include <sys/sysctl.h>
#if defined(__DragonFly__) || defined(__FreeBSD__)
#include <sys/user.h>
#endif

#include <unistd.h>

#if defined(__NetBSD__)
#undef KERN_PROC
#define KERN_PROC KERN_PROC2
#define KINFO_PROC struct kinfo_proc2
#else
#define KINFO_PROC struct kinfo_proc
#endif

#if defined(__DragonFly__)
#define KP_SIZE(kp) (kp.kp_vm_map_size)
#define KP_RSS(kp) (kp.kp_vm_rssize * getpagesize())
#elif defined(__FreeBSD__)
#define KP_SIZE(kp) (kp.ki_size)
#define KP_RSS(kp) (kp.ki_rssize * getpagesize())
#elif defined(__NetBSD__)
#define KP_SIZE(kp) (kp.p_vm_msize * getpagesize())
#define KP_RSS(kp) (kp.p_vm_rssize * getpagesize())
#elif defined(__OpenBSD__)
#define KP_SIZE(kp) ((kp.p_vm_dsize + kp.p_vm_ssize                     \
                      + kp.p_vm_tsize) * getpagesize())
#define KP_RSS(kp) (kp.p_vm_rssize * getpagesize())
#endif

static nsresult GetKinfoProcSelf(KINFO_PROC *proc)
{
    int mib[] = {
        CTL_KERN,
        KERN_PROC,
        KERN_PROC_PID,
        getpid(),
#if defined(__NetBSD__) || defined(__OpenBSD__)
        sizeof(KINFO_PROC),
        1,
#endif
    };
    u_int miblen = sizeof(mib) / sizeof(mib[0]);
    size_t size = sizeof(KINFO_PROC);
    if (sysctl(mib, miblen, proc, &size, NULL, 0))
        return NS_ERROR_FAILURE;

    return NS_OK;
}

#define HAVE_VSIZE_AND_RESIDENT_REPORTERS 1
static nsresult GetVsize(int64_t *n)
{
    KINFO_PROC proc;
    nsresult rv = GetKinfoProcSelf(&proc);
    if (NS_SUCCEEDED(rv))
        *n = KP_SIZE(proc);

    return rv;
}

static nsresult GetResident(int64_t *n)
{
    KINFO_PROC proc;
    nsresult rv = GetKinfoProcSelf(&proc);
    if (NS_SUCCEEDED(rv))
        *n = KP_RSS(proc);

    return rv;
}

#elif defined(SOLARIS)

#include <procfs.h>
#include <fcntl.h>
#include <unistd.h>

static void XMappingIter(int64_t& vsize, int64_t& resident)
{
    vsize = -1;
    resident = -1;
    int mapfd = open("/proc/self/xmap", O_RDONLY);
    struct stat st;
    prxmap_t *prmapp = NULL;
    if (mapfd >= 0) {
        if (!fstat(mapfd, &st)) {
            int nmap = st.st_size / sizeof(prxmap_t);
            while (1) {
                // stat(2) on /proc/<pid>/xmap returns an incorrect value,
                // prior to the release of Solaris 11.
                // Here is a workaround for it.
                nmap *= 2;
                prmapp = (prxmap_t*)malloc((nmap + 1) * sizeof(prxmap_t));
                if (!prmapp) {
                    // out of memory
                    break;
                }
                int n = pread(mapfd, prmapp, (nmap + 1) * sizeof(prxmap_t), 0);
                if (n < 0) {
                    break;
                }
                if (nmap >= n / sizeof (prxmap_t)) {
                    vsize = 0;
                    resident = 0;
                    for (int i = 0; i < n / sizeof (prxmap_t); i++) {
                        vsize += prmapp[i].pr_size;
                        resident += prmapp[i].pr_rss * prmapp[i].pr_pagesize;
                    }
                    break;
                }
                free(prmapp);
            }
            free(prmapp);
        }
        close(mapfd);
    }
}

#define HAVE_VSIZE_AND_RESIDENT_REPORTERS 1
static nsresult GetVsize(int64_t *n)
{
    int64_t vsize, resident;
    XMappingIter(vsize, resident);
    if (vsize == -1) {
        return NS_ERROR_FAILURE;
    }
    *n = vsize;
    return NS_OK;
}

static nsresult GetResident(int64_t *n)
{
    int64_t vsize, resident;
    XMappingIter(vsize, resident);
    if (resident == -1) {
        return NS_ERROR_FAILURE;
    }
    *n = resident;
    return NS_OK;
}

#elif defined(XP_MACOSX)

#include <mach/mach_init.h>
#include <mach/task.h>

static bool GetTaskBasicInfo(struct task_basic_info *ti)
{
    mach_msg_type_number_t count = TASK_BASIC_INFO_COUNT;
    kern_return_t kr = task_info(mach_task_self(), TASK_BASIC_INFO,
                                 (task_info_t)ti, &count);
    return kr == KERN_SUCCESS;
}

// The VSIZE figure on Mac includes huge amounts of shared memory and is always
// absurdly high, eg. 2GB+ even at start-up.  But both 'top' and 'ps' report
// it, so we might as well too.
#define HAVE_VSIZE_AND_RESIDENT_REPORTERS 1
static nsresult GetVsize(int64_t *n)
{
    task_basic_info ti;
    if (!GetTaskBasicInfo(&ti))
        return NS_ERROR_FAILURE;

    *n = ti.virtual_size;
    return NS_OK;
}

static nsresult GetResident(int64_t *n)
{
#ifdef HAVE_JEMALLOC_STATS
    // If we're using jemalloc on Mac, we need to instruct jemalloc to purge
    // the pages it has madvise(MADV_FREE)'d before we read our RSS.  The OS
    // will take away MADV_FREE'd pages when there's memory pressure, so they
    // shouldn't count against our RSS.
    //
    // Purging these pages shouldn't take more than 10ms or so, but we want to
    // keep an eye on it since GetResident() is called on each Telemetry ping.
    {
      Telemetry::AutoTimer<Telemetry::MEMORY_FREE_PURGED_PAGES_MS> timer;
      jemalloc_purge_freed_pages();
    }
#endif

    task_basic_info ti;
    if (!GetTaskBasicInfo(&ti))
        return NS_ERROR_FAILURE;

    *n = ti.resident_size;
    return NS_OK;
}

#elif defined(XP_WIN)

#include <windows.h>
#include <psapi.h>

#define HAVE_VSIZE_AND_RESIDENT_REPORTERS 1
static nsresult GetVsize(int64_t *n)
{
    MEMORYSTATUSEX s;
    s.dwLength = sizeof(s);

    if (!GlobalMemoryStatusEx(&s)) {
        return NS_ERROR_FAILURE;
    }

    *n = s.ullTotalVirtual - s.ullAvailVirtual;
    return NS_OK;
}

static nsresult GetResident(int64_t *n)
{
    PROCESS_MEMORY_COUNTERS pmc;
    pmc.cb = sizeof(PROCESS_MEMORY_COUNTERS);

    if (!GetProcessMemoryInfo(GetCurrentProcess(), &pmc, sizeof(pmc))) {
        return NS_ERROR_FAILURE;
    }

    *n = pmc.WorkingSetSize;
    return NS_OK;
}

#define HAVE_PRIVATE_REPORTER
static nsresult GetPrivate(int64_t *n)
{
    PROCESS_MEMORY_COUNTERS_EX pmcex;
    pmcex.cb = sizeof(PROCESS_MEMORY_COUNTERS_EX);

    if (!GetProcessMemoryInfo(GetCurrentProcess(),
                              (PPROCESS_MEMORY_COUNTERS) &pmcex, sizeof(pmcex)))
    {
        return NS_ERROR_FAILURE;
    }

    *n = pmcex.PrivateUsage;
    return NS_OK;
}

NS_FALLIBLE_MEMORY_REPORTER_IMPLEMENT(Private,
    "private",
    KIND_OTHER,
    UNITS_BYTES,
    GetPrivate,
    "Memory that cannot be shared with other processes, including memory that "
    "is committed and marked MEM_PRIVATE, data that is not mapped, and "
    "executable pages that have been written to.")

#endif  // XP_<PLATFORM>

#ifdef HAVE_VSIZE_AND_RESIDENT_REPORTERS
NS_FALLIBLE_MEMORY_REPORTER_IMPLEMENT(Vsize,
    "vsize",
    KIND_OTHER,
    UNITS_BYTES,
    GetVsize,
    "Memory mapped by the process, including code and data segments, the "
    "heap, thread stacks, memory explicitly mapped by the process via mmap "
    "and similar operations, and memory shared with other processes. "
    "This is the vsize figure as reported by 'top' and 'ps'.  This figure is of "
    "limited use on Mac, where processes share huge amounts of memory with one "
    "another.  But even on other operating systems, 'resident' is a much better "
    "measure of the memory resources used by the process.")

NS_FALLIBLE_MEMORY_REPORTER_IMPLEMENT(Resident,
    "resident",
    KIND_OTHER,
    UNITS_BYTES,
    GetResident,
    "Memory mapped by the process that is present in physical memory, "
    "also known as the resident set size (RSS).  This is the best single "
    "figure to use when considering the memory resources used by the process, "
    "but it depends both on other processes being run and details of the OS "
    "kernel and so is best used for comparing the memory usage of a single "
    "process at different points in time.")
#endif  // HAVE_VSIZE_AND_RESIDENT_REPORTERS

#ifdef HAVE_PAGE_FAULT_REPORTERS
NS_FALLIBLE_MEMORY_REPORTER_IMPLEMENT(PageFaultsSoft,
    "page-faults-soft",
    KIND_OTHER,
    UNITS_COUNT_CUMULATIVE,
    GetSoftPageFaults,
    "The number of soft page faults (also known as 'minor page faults') that "
    "have occurred since the process started.  A soft page fault occurs when the "
    "process tries to access a page which is present in physical memory but is "
    "not mapped into the process's address space.  For instance, a process might "
    "observe soft page faults when it loads a shared library which is already "
    "present in physical memory. A process may experience many thousands of soft "
    "page faults even when the machine has plenty of available physical memory, "
    "and because the OS services a soft page fault without accessing the disk, "
    "they impact performance much less than hard page faults.")

NS_FALLIBLE_MEMORY_REPORTER_IMPLEMENT(PageFaultsHard,
    "page-faults-hard",
    KIND_OTHER,
    UNITS_COUNT_CUMULATIVE,
    GetHardPageFaults,
    "The number of hard page faults (also known as 'major page faults') that "
    "have occurred since the process started.  A hard page fault occurs when a "
    "process tries to access a page which is not present in physical memory. "
    "The operating system must access the disk in order to fulfill a hard page "
    "fault. When memory is plentiful, you should see very few hard page faults. "
    "But if the process tries to use more memory than your machine has "
    "available, you may see many thousands of hard page faults. Because "
    "accessing the disk is up to a million times slower than accessing RAM, "
    "the program may run very slowly when it is experiencing more than 100 or "
    "so hard page faults a second.")
#endif  // HAVE_PAGE_FAULT_REPORTERS

/**
 ** memory reporter implementation for jemalloc and OSX malloc,
 ** to obtain info on total memory in use (that we know about,
 ** at least -- on OSX, there are sometimes other zones in use).
 **/

#if HAVE_JEMALLOC_STATS

static int64_t GetHeapUnused()
{
    jemalloc_stats_t stats;
    jemalloc_stats(&stats);
    return (int64_t) (stats.mapped - stats.allocated);
}

static int64_t GetHeapAllocated()
{
    jemalloc_stats_t stats;
    jemalloc_stats(&stats);
    return (int64_t) stats.allocated;
}

static int64_t GetHeapCommitted()
{
    jemalloc_stats_t stats;
    jemalloc_stats(&stats);
    return (int64_t) stats.committed;
}

static int64_t GetHeapCommittedUnused()
{
    jemalloc_stats_t stats;
    jemalloc_stats(&stats);
    return stats.committed - stats.allocated;
}

static int64_t GetHeapCommittedUnusedRatio()
{
    jemalloc_stats_t stats;
    jemalloc_stats(&stats);
    return (int64_t) 10000 * (stats.committed - stats.allocated) /
                              ((double)stats.allocated);
}

static int64_t GetHeapDirty()
{
    jemalloc_stats_t stats;
    jemalloc_stats(&stats);
    return (int64_t) stats.dirty;
}

NS_MEMORY_REPORTER_IMPLEMENT(HeapCommitted,
    "heap-committed",
    KIND_OTHER,
    UNITS_BYTES,
    GetHeapCommitted,
    "Memory mapped by the heap allocator that is committed, i.e. in physical "
    "memory or paged to disk.  When heap-committed is larger than "
    "heap-allocated, the difference between the two values is likely due to "
    "external fragmentation; that is, the allocator allocated a large block of "
    "memory and is unable to decommit it because a small part of that block is "
    "currently in use.")

NS_MEMORY_REPORTER_IMPLEMENT(HeapCommittedUnused,
    "heap-committed-unused",
    KIND_OTHER,
    UNITS_BYTES,
    GetHeapCommittedUnused,
    "Committed bytes which do not correspond to an active allocation; i.e., "
    "'heap-committed' - 'heap-allocated'.  Although the allocator will waste some "
    "space under any circumstances, a large value here may indicate that the "
    "heap is highly fragmented.")

NS_MEMORY_REPORTER_IMPLEMENT(HeapCommittedUnusedRatio,
    "heap-committed-unused-ratio",
    KIND_OTHER,
    UNITS_PERCENTAGE,
    GetHeapCommittedUnusedRatio,
    "Ratio of committed, unused bytes to allocated bytes; i.e., "
    "'heap-committed-unused' / 'heap-allocated'.  This measures the overhead "
    "of the heap allocator relative to amount of memory allocated.")

NS_MEMORY_REPORTER_IMPLEMENT(HeapDirty,
    "heap-dirty",
    KIND_OTHER,
    UNITS_BYTES,
    GetHeapDirty,
    "Memory which the allocator could return to the operating system, but "
    "hasn't.  The allocator keeps this memory around as an optimization, so it "
    "doesn't have to ask the OS the next time it needs to fulfill a request. "
    "This value is typically not larger than a few megabytes.")

NS_MEMORY_REPORTER_IMPLEMENT(HeapUnused,
    "heap-unused",
    KIND_OTHER,
    UNITS_BYTES,
    GetHeapUnused,
    "Memory mapped by the heap allocator that is not part of an active "
    "allocation. Much of this memory may be uncommitted -- that is, it does not "
    "take up space in physical memory or in the swap file.")

NS_MEMORY_REPORTER_IMPLEMENT(HeapAllocated,
    "heap-allocated",
    KIND_OTHER,
    UNITS_BYTES,
    GetHeapAllocated,
    "Memory mapped by the heap allocator that is currently allocated to the "
    "application.  This may exceed the amount of memory requested by the "
    "application because the allocator regularly rounds up request sizes. (The "
    "exact amount requested is not recorded.)")

// The computation of "explicit" fails if "heap-allocated" isn't available,
// which is why this is depends on HAVE_JEMALLOC_STATS.
static nsresult GetExplicit(int64_t *n)
{
    nsCOMPtr<nsIMemoryReporterManager> mgr = do_GetService("@mozilla.org/memory-reporter-manager;1");
    if (mgr == nullptr)
        return NS_ERROR_FAILURE;

    return mgr->GetExplicit(n);
}

NS_FALLIBLE_MEMORY_REPORTER_IMPLEMENT(Explicit,
    "explicit",
    KIND_OTHER,
    UNITS_BYTES,
    GetExplicit,
    "This is the same measurement as the root of the 'explicit' tree.  "
    "However, it is measured at a different time and so gives slightly "
    "different results.")
#endif  // HAVE_JEMALLOC_STATS

NS_MEMORY_REPORTER_MALLOC_SIZEOF_FUN(AtomTableMallocSizeOf)

static int64_t GetAtomTableSize() {
  return NS_SizeOfAtomTablesIncludingThis(AtomTableMallocSizeOf);
}

// Why is this here?  At first glance, you'd think it could be defined and
// registered with nsMemoryReporterManager entirely within nsAtomTable.cpp.
// However, the obvious time to register it is when the table is initialized,
// and that happens before XPCOM components are initialized, which means the
// NS_RegisterMemoryReporter call fails.  So instead we do it here.
NS_MEMORY_REPORTER_IMPLEMENT(AtomTable,
    "explicit/atom-tables",
    KIND_HEAP,
    UNITS_BYTES,
    GetAtomTableSize,
    "Memory used by the dynamic and static atoms tables.")

#ifdef MOZ_DMD

namespace mozilla {
namespace dmd {

class MemoryReporter MOZ_FINAL : public nsIMemoryMultiReporter
{
public:
  MemoryReporter()
  {}

  NS_DECL_ISUPPORTS

  NS_IMETHOD GetName(nsACString &name)
  {
    name.Assign("dmd");
    return NS_OK;
  }

  NS_IMETHOD CollectReports(nsIMemoryMultiReporterCallback *callback,
                            nsISupports *closure)
  {
    dmd::Sizes sizes;
    dmd::SizeOf(&sizes);

#define REPORT(_path, _amount, _desc)                                         \
    do {                                                                      \
      nsresult rv;                                                            \
      rv = callback->Callback(EmptyCString(), NS_LITERAL_CSTRING(_path),      \
                              nsIMemoryReporter::KIND_HEAP,                   \
                              nsIMemoryReporter::UNITS_BYTES, _amount,        \
                              NS_LITERAL_CSTRING(_desc), closure);            \
      NS_ENSURE_SUCCESS(rv, rv);                                              \
    } while (0)

    REPORT("explicit/dmd/stack-traces/used",
           sizes.mStackTracesUsed,
           "Memory used by stack traces which correspond to at least "
           "one heap block DMD is tracking.");

    REPORT("explicit/dmd/stack-traces/unused",
           sizes.mStackTracesUnused,
           "Memory used by stack traces which don't correspond to any heap "
           "blocks DMD is currently tracking.");

    REPORT("explicit/dmd/stack-traces/table",
           sizes.mStackTraceTable,
           "Memory used by DMD's stack trace table.");

    REPORT("explicit/dmd/block-table",
           sizes.mBlockTable,
           "Memory used by DMD's live block table.");

#undef REPORT

    return NS_OK;
  }

  NS_IMETHOD GetExplicitNonHeap(int64_t *n)
  {
    // No non-heap allocations.
    *n = 0;
    return NS_OK;
  }

};

NS_IMPL_ISUPPORTS1(MemoryReporter, nsIMemoryMultiReporter)

} // namespace dmd
} // namespace mozilla

#endif  // MOZ_DMD

/**
 ** nsMemoryReporterManager implementation
 **/

NS_IMPL_THREADSAFE_ISUPPORTS1(nsMemoryReporterManager, nsIMemoryReporterManager)

NS_IMETHODIMP
nsMemoryReporterManager::Init()
{
#if HAVE_JEMALLOC_STATS && defined(XP_LINUX)
    if (!jemalloc_stats)
        return NS_ERROR_FAILURE;
#endif

#define REGISTER(_x)  RegisterReporter(new NS_MEMORY_REPORTER_NAME(_x))

#ifdef HAVE_JEMALLOC_STATS
    REGISTER(HeapAllocated);
    REGISTER(HeapUnused);
    REGISTER(HeapCommitted);
    REGISTER(HeapCommittedUnused);
    REGISTER(HeapCommittedUnusedRatio);
    REGISTER(HeapDirty);
    REGISTER(Explicit);
#endif

#ifdef HAVE_VSIZE_AND_RESIDENT_REPORTERS
    REGISTER(Vsize);
    REGISTER(Resident);
#endif

#ifdef HAVE_PAGE_FAULT_REPORTERS
    REGISTER(PageFaultsSoft);
    REGISTER(PageFaultsHard);
#endif

#ifdef HAVE_PRIVATE_REPORTER
    REGISTER(Private);
#endif

    REGISTER(AtomTable);

#ifdef MOZ_DMD
    RegisterMultiReporter(new mozilla::dmd::MemoryReporter);
#endif

#if defined(XP_LINUX)
    nsMemoryInfoDumper::Initialize();
#endif

    return NS_OK;
}

nsMemoryReporterManager::nsMemoryReporterManager()
  : mMutex("nsMemoryReporterManager::mMutex")
{
}

nsMemoryReporterManager::~nsMemoryReporterManager()
{
}

NS_IMETHODIMP
nsMemoryReporterManager::EnumerateReporters(nsISimpleEnumerator **result)
{
    nsresult rv;
    mozilla::MutexAutoLock autoLock(mMutex);
    rv = NS_NewArrayEnumerator(result, mReporters);
    return rv;
}

NS_IMETHODIMP
nsMemoryReporterManager::EnumerateMultiReporters(nsISimpleEnumerator **result)
{
    nsresult rv;
    mozilla::MutexAutoLock autoLock(mMutex);
    rv = NS_NewArrayEnumerator(result, mMultiReporters);
    return rv;
}

NS_IMETHODIMP
nsMemoryReporterManager::RegisterReporter(nsIMemoryReporter *reporter)
{
    mozilla::MutexAutoLock autoLock(mMutex);
    if (mReporters.IndexOf(reporter) != -1)
        return NS_ERROR_FAILURE;

    mReporters.AppendObject(reporter);
    return NS_OK;
}

NS_IMETHODIMP
nsMemoryReporterManager::RegisterMultiReporter(nsIMemoryMultiReporter *reporter)
{
    mozilla::MutexAutoLock autoLock(mMutex);
    if (mMultiReporters.IndexOf(reporter) != -1)
        return NS_ERROR_FAILURE;

    mMultiReporters.AppendObject(reporter);
    return NS_OK;
}

NS_IMETHODIMP
nsMemoryReporterManager::UnregisterReporter(nsIMemoryReporter *reporter)
{
    mozilla::MutexAutoLock autoLock(mMutex);
    if (!mReporters.RemoveObject(reporter))
        return NS_ERROR_FAILURE;

    return NS_OK;
}

NS_IMETHODIMP
nsMemoryReporterManager::UnregisterMultiReporter(nsIMemoryMultiReporter *reporter)
{
    mozilla::MutexAutoLock autoLock(mMutex);
    if (!mMultiReporters.RemoveObject(reporter))
        return NS_ERROR_FAILURE;

    return NS_OK;
}

NS_IMETHODIMP
nsMemoryReporterManager::GetResident(int64_t *aResident)
{
#if HAVE_VSIZE_AND_RESIDENT_REPORTERS
    return ::GetResident(aResident);
#else
    *aResident = 0;
    return NS_ERROR_NOT_AVAILABLE;
#endif
}

struct MemoryReport {
    MemoryReport(const nsACString &path, int64_t amount) 
    : path(path), amount(amount)
    {
        MOZ_COUNT_CTOR(MemoryReport);
    }
    MemoryReport(const MemoryReport& rhs)
    : path(rhs.path), amount(rhs.amount)
    {
        MOZ_COUNT_CTOR(MemoryReport);
    }
    ~MemoryReport() 
    {
        MOZ_COUNT_DTOR(MemoryReport);
    }
    const nsCString path;
    int64_t amount;
};

#if defined(DEBUG) && !defined(MOZ_DMD)
// This is just a wrapper for int64_t that implements nsISupports, so it can be
// passed to nsIMemoryMultiReporter::CollectReports.
class Int64Wrapper MOZ_FINAL : public nsISupports {
public:
    NS_DECL_ISUPPORTS
    Int64Wrapper() : mValue(0) { }
    int64_t mValue;
};
NS_IMPL_ISUPPORTS0(Int64Wrapper)

class ExplicitNonHeapCountingCallback MOZ_FINAL : public nsIMemoryMultiReporterCallback
{
public:
    NS_DECL_ISUPPORTS

    NS_IMETHOD Callback(const nsACString &aProcess, const nsACString &aPath,
                        int32_t aKind, int32_t aUnits, int64_t aAmount,
                        const nsACString &aDescription,
                        nsISupports *aWrappedExplicitNonHeap)
    {
        if (aKind == nsIMemoryReporter::KIND_NONHEAP &&
            PromiseFlatCString(aPath).Find("explicit") == 0 &&
            aAmount != int64_t(-1))
        {
            Int64Wrapper *wrappedPRInt64 =
                static_cast<Int64Wrapper *>(aWrappedExplicitNonHeap);
            wrappedPRInt64->mValue += aAmount;
        }
        return NS_OK;
    }
};
NS_IMPL_ISUPPORTS1(
  ExplicitNonHeapCountingCallback
, nsIMemoryMultiReporterCallback
)
#endif  // defined(DEBUG) && !defined(MOZ_DMD)

NS_IMETHODIMP
nsMemoryReporterManager::GetExplicit(int64_t *aExplicit)
{
    NS_ENSURE_ARG_POINTER(aExplicit);
    *aExplicit = 0;
#ifndef HAVE_JEMALLOC_STATS
    return NS_ERROR_NOT_AVAILABLE;
#else
    nsresult rv;
    bool more;

    // Get "heap-allocated" and all the KIND_NONHEAP measurements from normal
    // (i.e. non-multi) "explicit" reporters.
    int64_t heapAllocated = int64_t(-1);
    int64_t explicitNonHeapNormalSize = 0;
    nsCOMPtr<nsISimpleEnumerator> e;
    EnumerateReporters(getter_AddRefs(e));
    while (NS_SUCCEEDED(e->HasMoreElements(&more)) && more) {
        nsCOMPtr<nsIMemoryReporter> r;
        e->GetNext(getter_AddRefs(r));

        int32_t kind;
        rv = r->GetKind(&kind);
        NS_ENSURE_SUCCESS(rv, rv);

        nsCString path;
        rv = r->GetPath(path);
        NS_ENSURE_SUCCESS(rv, rv);

        // We're only interested in NONHEAP explicit reporters and
        // the 'heap-allocated' reporter.
        if (kind == nsIMemoryReporter::KIND_NONHEAP &&
            path.Find("explicit") == 0)
        {
            // Just skip any NONHEAP reporters that fail, because
            // "heap-allocated" is the most important one.
            int64_t amount;
            rv = r->GetAmount(&amount);
            if (NS_SUCCEEDED(rv)) {
                explicitNonHeapNormalSize += amount;
            }
        } else if (path.Equals("heap-allocated")) {
            // If we don't have "heap-allocated", give up, because the result
            // would be horribly inaccurate.
            rv = r->GetAmount(&heapAllocated);
            NS_ENSURE_SUCCESS(rv, rv);
        }
    }

    // For each multi-reporter we could call CollectReports and filter out the
    // non-explicit, non-NONHEAP measurements.  But that's lots of wasted work,
    // so we instead use GetExplicitNonHeap() which exists purely for this
    // purpose.
    //
    // (Actually, in debug builds we also do it the slow way and compare the
    // result to the result obtained from GetExplicitNonHeap().  This
    // guarantees the two measurement paths are equivalent.  This is wise
    // because it's easy for memory reporters to have bugs.  But there's an
    // exception if DMD is enabled, because that makes DMD think that all the
    // blocks are double-counted.)

    int64_t explicitNonHeapMultiSize = 0;
    nsCOMPtr<nsISimpleEnumerator> e2;
    EnumerateMultiReporters(getter_AddRefs(e2));
    while (NS_SUCCEEDED(e2->HasMoreElements(&more)) && more) {
      nsCOMPtr<nsIMemoryMultiReporter> r;
      e2->GetNext(getter_AddRefs(r));
      int64_t n;
      rv = r->GetExplicitNonHeap(&n);
      NS_ENSURE_SUCCESS(rv, rv);
      explicitNonHeapMultiSize += n;
    }

#if defined(DEBUG) && !defined(MOZ_DMD)
    nsRefPtr<ExplicitNonHeapCountingCallback> cb =
      new ExplicitNonHeapCountingCallback();
    nsRefPtr<Int64Wrapper> wrappedExplicitNonHeapMultiSize2 =
      new Int64Wrapper();
    nsCOMPtr<nsISimpleEnumerator> e3;
    EnumerateMultiReporters(getter_AddRefs(e3));
    while (NS_SUCCEEDED(e3->HasMoreElements(&more)) && more) {
      nsCOMPtr<nsIMemoryMultiReporter> r;
      e3->GetNext(getter_AddRefs(r));
      r->CollectReports(cb, wrappedExplicitNonHeapMultiSize2);
    }
    int64_t explicitNonHeapMultiSize2 = wrappedExplicitNonHeapMultiSize2->mValue;

    // Check the two measurements give the same result.  This was an
    // NS_ASSERTION but they occasionally don't match due to races (bug
    // 728990).
    if (explicitNonHeapMultiSize != explicitNonHeapMultiSize2) {
        NS_WARNING(nsPrintfCString("The two measurements of 'explicit' memory "
                                   "usage don't match (%lld vs %lld)",
                                   explicitNonHeapMultiSize,
                                   explicitNonHeapMultiSize2).get());
    }
#endif  // defined(DEBUG) && !defined(MOZ_DMD)

    *aExplicit = heapAllocated + explicitNonHeapNormalSize + explicitNonHeapMultiSize;
    return NS_OK;
#endif // HAVE_JEMALLOC_STATS
}

NS_IMETHODIMP
nsMemoryReporterManager::GetHasMozMallocUsableSize(bool *aHas)
{
    void *p = malloc(16);
    if (!p) {
        return NS_ERROR_OUT_OF_MEMORY;
    }
    size_t usable = moz_malloc_usable_size(p);
    free(p);
    *aHas = !!(usable > 0);
    return NS_OK;
}

namespace {

/**
 * This runnable lets us implement nsIMemoryReporterManager::MinimizeMemoryUsage().
 * We fire a heap-minimize notification, spin the event loop, and repeat this
 * process a few times.
 *
 * When this sequence finishes, we invoke the callback function passed to the
 * runnable's constructor.
 */
class MinimizeMemoryUsageRunnable : public nsCancelableRunnable
{
public:
  MinimizeMemoryUsageRunnable(nsIRunnable* aCallback)
    : mCallback(aCallback)
    , mRemainingIters(sNumIters)
    , mCanceled(false)
  {}

  NS_IMETHOD Run()
  {
    if (mCanceled) {
      return NS_OK;
    }

    nsCOMPtr<nsIObserverService> os = services::GetObserverService();
    if (!os) {
      return NS_ERROR_FAILURE;
    }

    if (mRemainingIters == 0) {
      os->NotifyObservers(nullptr, "after-minimize-memory-usage",
                          NS_LITERAL_STRING("MinimizeMemoryUsageRunnable").get());
      if (mCallback) {
        mCallback->Run();
      }
      return NS_OK;
    }

    os->NotifyObservers(nullptr, "memory-pressure",
                        NS_LITERAL_STRING("heap-minimize").get());
    mRemainingIters--;
    NS_DispatchToMainThread(this);

    return NS_OK;
  }

  NS_IMETHOD Cancel()
  {
    if (mCanceled) {
      return NS_ERROR_UNEXPECTED;
    }

    mCanceled = true;

    return NS_OK;
  }

private:
  // Send sNumIters heap-minimize notifications, spinning the event
  // loop after each notification (see bug 610166 comment 12 for an
  // explanation), because one notification doesn't cut it.
  static const uint32_t sNumIters = 3;

  nsCOMPtr<nsIRunnable> mCallback;
  uint32_t mRemainingIters;
  bool mCanceled;
};

} // anonymous namespace

NS_IMETHODIMP
nsMemoryReporterManager::MinimizeMemoryUsage(nsIRunnable* aCallback,
                                             nsICancelableRunnable **result)
{
  NS_ENSURE_ARG_POINTER(result);

  nsRefPtr<nsICancelableRunnable> runnable =
    new MinimizeMemoryUsageRunnable(aCallback);
  NS_ADDREF(*result = runnable);

  return NS_DispatchToMainThread(runnable);
}

NS_IMPL_ISUPPORTS1(nsMemoryReporter, nsIMemoryReporter)

nsMemoryReporter::nsMemoryReporter(nsACString& process,
                                   nsACString& path,
                                   int32_t kind,
                                   int32_t units,
                                   int64_t amount,
                                   nsACString& desc)
: mProcess(process)
, mPath(path)
, mKind(kind)
, mUnits(units)
, mAmount(amount)
, mDesc(desc)
{
}

nsMemoryReporter::~nsMemoryReporter()
{
}

NS_IMETHODIMP nsMemoryReporter::GetProcess(nsACString &aProcess)
{
    aProcess.Assign(mProcess);
    return NS_OK;
}

NS_IMETHODIMP nsMemoryReporter::GetPath(nsACString &aPath)
{
    aPath.Assign(mPath);
    return NS_OK;
}

NS_IMETHODIMP nsMemoryReporter::GetKind(int32_t *aKind)
{
    *aKind = mKind;
    return NS_OK;
}

NS_IMETHODIMP nsMemoryReporter::GetUnits(int32_t *aUnits)
{
  *aUnits = mUnits;
  return NS_OK;
}

NS_IMETHODIMP nsMemoryReporter::GetAmount(int64_t *aAmount)
{
    *aAmount = mAmount;
    return NS_OK;
}

NS_IMETHODIMP nsMemoryReporter::GetDescription(nsACString &aDescription)
{
    aDescription.Assign(mDesc);
    return NS_OK;
}

nsresult
NS_RegisterMemoryReporter (nsIMemoryReporter *reporter)
{
    nsCOMPtr<nsIMemoryReporterManager> mgr = do_GetService("@mozilla.org/memory-reporter-manager;1");
    if (mgr == nullptr)
        return NS_ERROR_FAILURE;
    return mgr->RegisterReporter(reporter);
}

nsresult
NS_RegisterMemoryMultiReporter (nsIMemoryMultiReporter *reporter)
{
    nsCOMPtr<nsIMemoryReporterManager> mgr = do_GetService("@mozilla.org/memory-reporter-manager;1");
    if (mgr == nullptr)
        return NS_ERROR_FAILURE;
    return mgr->RegisterMultiReporter(reporter);
}

nsresult
NS_UnregisterMemoryReporter (nsIMemoryReporter *reporter)
{
    nsCOMPtr<nsIMemoryReporterManager> mgr = do_GetService("@mozilla.org/memory-reporter-manager;1");
    if (mgr == nullptr)
        return NS_ERROR_FAILURE;
    return mgr->UnregisterReporter(reporter);
}

nsresult
NS_UnregisterMemoryMultiReporter (nsIMemoryMultiReporter *reporter)
{
    nsCOMPtr<nsIMemoryReporterManager> mgr = do_GetService("@mozilla.org/memory-reporter-manager;1");
    if (mgr == nullptr)
        return NS_ERROR_FAILURE;
    return mgr->UnregisterMultiReporter(reporter);
}

#if defined(MOZ_DMD)

namespace mozilla {
namespace dmd {

class NullMultiReporterCallback : public nsIMemoryMultiReporterCallback
{
public:
    NS_DECL_ISUPPORTS

    NS_IMETHOD Callback(const nsACString &aProcess, const nsACString &aPath,
                        int32_t aKind, int32_t aUnits, int64_t aAmount,
                        const nsACString &aDescription,
                        nsISupports *aData)
    {
        // Do nothing;  the reporter has already reported to DMD.
        return NS_OK;
    }
};
NS_IMPL_ISUPPORTS1(
  NullMultiReporterCallback
, nsIMemoryMultiReporterCallback
)

void
RunReporters()
{
    nsCOMPtr<nsIMemoryReporterManager> mgr =
        do_GetService("@mozilla.org/memory-reporter-manager;1");

    // Do vanilla reporters.
    nsCOMPtr<nsISimpleEnumerator> e;
    mgr->EnumerateReporters(getter_AddRefs(e));
    bool more;
    while (NS_SUCCEEDED(e->HasMoreElements(&more)) && more) {
        nsCOMPtr<nsIMemoryReporter> r;
        e->GetNext(getter_AddRefs(r));

        int32_t kind;
        nsresult rv = r->GetKind(&kind);
        if (NS_FAILED(rv)) {
            continue;
        }
        nsCString path;
        rv = r->GetPath(path);
        if (NS_FAILED(rv)) {
            continue;
        }

        // We're only interested in HEAP explicit reporters.  (In particular,
        // some heap blocks are deliberately measured once inside an "explicit"
        // reporter and once outside, which isn't a problem.  This condition
        // prevents them being reported as double-counted.  See bug 811018
        // comment 2.)
        if (kind == nsIMemoryReporter::KIND_HEAP &&
            path.Find("explicit") == 0)
        {
            // Just getting the amount is enough for the reporter to report to
            // DMD.
            int64_t amount;
            (void)r->GetAmount(&amount);
        }
    }

    // Do multi-reporters.
    nsCOMPtr<nsISimpleEnumerator> e2;
    mgr->EnumerateMultiReporters(getter_AddRefs(e2));
    nsRefPtr<NullMultiReporterCallback> cb = new NullMultiReporterCallback();
    while (NS_SUCCEEDED(e2->HasMoreElements(&more)) && more) {
      nsCOMPtr<nsIMemoryMultiReporter> r;
      e2->GetNext(getter_AddRefs(r));
      r->CollectReports(cb, nullptr);
    }
}

} // namespace dmd
} // namespace mozilla

#endif  // defined(MOZ_DMD)