DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Header

Mercurial (d42c22627c8d)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166
/* -*- 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 "nsMemoryImpl.h"
#include "nsThreadUtils.h"

#include "nsIObserver.h"
#include "nsIObserverService.h"
#include "nsISimpleEnumerator.h"

#include "nsCOMPtr.h"
#include "mozilla/Services.h"

#ifdef ANDROID
#  include <stdio.h>

// Minimum memory threshold for a device to be considered
// a low memory platform. This value has be in sync with
// Java's equivalent threshold, defined in
// mobile/android/base/util/HardwareUtils.java
#  define LOW_MEMORY_THRESHOLD_KB (384 * 1024)
#endif

static nsMemoryImpl sGlobalMemory;

NS_IMPL_QUERY_INTERFACE(nsMemoryImpl, nsIMemory)

NS_IMETHODIMP
nsMemoryImpl::HeapMinimize(bool aImmediate) {
  return FlushMemory(u"heap-minimize", aImmediate);
}

NS_IMETHODIMP
nsMemoryImpl::IsLowMemoryPlatform(bool* aResult) {
#ifdef ANDROID
  static int sLowMemory =
      -1;  // initialize to unknown, lazily evaluate to 0 or 1
  if (sLowMemory == -1) {
    sLowMemory = 0;  // assume "not low memory" in case file operations fail
    *aResult = false;

    // check if MemTotal from /proc/meminfo is less than LOW_MEMORY_THRESHOLD_KB
    FILE* fd = fopen("/proc/meminfo", "r");
    if (!fd) {
      return NS_OK;
    }
    uint64_t mem = 0;
    int rv = fscanf(fd, "MemTotal: %" PRIu64 " kB", &mem);
    if (fclose(fd)) {
      return NS_OK;
    }
    if (rv != 1) {
      return NS_OK;
    }
    sLowMemory = (mem < LOW_MEMORY_THRESHOLD_KB) ? 1 : 0;
  }
  *aResult = (sLowMemory == 1);
#else
  *aResult = false;
#endif
  return NS_OK;
}

/*static*/
nsresult nsMemoryImpl::Create(nsISupports* aOuter, const nsIID& aIID,
                              void** aResult) {
  if (NS_WARN_IF(aOuter)) {
    return NS_ERROR_NO_AGGREGATION;
  }
  return sGlobalMemory.QueryInterface(aIID, aResult);
}

nsresult nsMemoryImpl::FlushMemory(const char16_t* aReason, bool aImmediate) {
  nsresult rv = NS_OK;

  if (aImmediate) {
    // They've asked us to run the flusher *immediately*. We've
    // got to be on the UI main thread for us to be able to do
    // that...are we?
    if (!NS_IsMainThread()) {
      NS_ERROR("can't synchronously flush memory: not on UI thread");
      return NS_ERROR_FAILURE;
    }
  }

  bool lastVal = sIsFlushing.exchange(true);
  if (lastVal) {
    return NS_OK;
  }

  PRIntervalTime now = PR_IntervalNow();

  // Run the flushers immediately if we can; otherwise, proxy to the
  // UI thread an run 'em asynchronously.
  if (aImmediate) {
    rv = RunFlushers(aReason);
  } else {
    // Don't broadcast more than once every 1000ms to avoid being noisy
    if (PR_IntervalToMicroseconds(now - sLastFlushTime) > 1000) {
      sFlushEvent.mReason = aReason;
      rv = NS_DispatchToMainThread(&sFlushEvent);
    }
  }

  sLastFlushTime = now;
  return rv;
}

nsresult nsMemoryImpl::RunFlushers(const char16_t* aReason) {
  nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
  if (os) {
    // Instead of:
    //  os->NotifyObservers(this, "memory-pressure", aReason);
    // we are going to do this manually to see who/what is
    // deallocating.

    nsCOMPtr<nsISimpleEnumerator> e;
    os->EnumerateObservers("memory-pressure", getter_AddRefs(e));

    if (e) {
      nsCOMPtr<nsIObserver> observer;
      bool loop = true;

      while (NS_SUCCEEDED(e->HasMoreElements(&loop)) && loop) {
        nsCOMPtr<nsISupports> supports;
        e->GetNext(getter_AddRefs(supports));

        if (!supports) {
          continue;
        }

        observer = do_QueryInterface(supports);
        observer->Observe(observer, "memory-pressure", aReason);
      }
    }
  }

  sIsFlushing = false;
  return NS_OK;
}

// XXX need NS_IMPL_STATIC_ADDREF/RELEASE
NS_IMETHODIMP_(MozExternalRefCountType)
nsMemoryImpl::FlushEvent::AddRef() { return 2; }
NS_IMETHODIMP_(MozExternalRefCountType)
nsMemoryImpl::FlushEvent::Release() { return 1; }
NS_IMPL_QUERY_INTERFACE(nsMemoryImpl::FlushEvent, nsIRunnable)

NS_IMETHODIMP
nsMemoryImpl::FlushEvent::Run() {
  sGlobalMemory.RunFlushers(mReason);
  return NS_OK;
}

mozilla::Atomic<bool> nsMemoryImpl::sIsFlushing;

PRIntervalTime nsMemoryImpl::sLastFlushTime = 0;

nsMemoryImpl::FlushEvent nsMemoryImpl::sFlushEvent;

nsresult NS_GetMemoryManager(nsIMemory** aResult) {
  return sGlobalMemory.QueryInterface(NS_GET_IID(nsIMemory), (void**)aResult);
}