xpcom/base/nsMemoryImpl.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "nsMemoryImpl.h"
   8 #include "nsThreadUtils.h"
   9
  10 #include "nsIObserver.h"
  11 #include "nsIObserverService.h"
  12 #include "nsISimpleEnumerator.h"
  13
  14 #include "nsCOMPtr.h"
  15 #include "mozilla/Services.h"
  16
  17 #ifdef ANDROID
  18 #  include <stdio.h>
  19
  20 // Minimum memory threshold for a device to be considered
  21 // a low memory platform. This value has be in sync with
  22 // Java's equivalent threshold, defined in
  23 // mobile/android/base/util/HardwareUtils.java
  24 #  define LOW_MEMORY_THRESHOLD_KB (384 * 1024)
  25 #endif
  26
  27 static nsMemoryImpl sGlobalMemory;
  28
  29 NS_IMPL_QUERY_INTERFACE(nsMemoryImpl, nsIMemory)
  30
  31 NS_IMETHODIMP
  32 nsMemoryImpl::HeapMinimize(bool aImmediate) {
  33   return FlushMemory(u"heap-minimize", aImmediate);
  34 }
  35
  36 NS_IMETHODIMP
  37 nsMemoryImpl::IsLowMemoryPlatform(bool* aResult) {
  38 #ifdef ANDROID
  39   static int sLowMemory =
  40       -1;  // initialize to unknown, lazily evaluate to 0 or 1
  41   if (sLowMemory == -1) {
  42     sLowMemory = 0;  // assume "not low memory" in case file operations fail
  43     *aResult = false;
  44
  45     // check if MemTotal from /proc/meminfo is less than LOW_MEMORY_THRESHOLD_KB
  46     FILE* fd = fopen("/proc/meminfo", "r");
  47     if (!fd) {
  48       return NS_OK;
  49     }
  50     uint64_t mem = 0;
  51     int rv = fscanf(fd, "MemTotal: %" PRIu64 " kB", &mem);
  52     if (fclose(fd)) {
  53       return NS_OK;
  54     }
  55     if (rv != 1) {
  56       return NS_OK;
  57     }
  58     sLowMemory = (mem < LOW_MEMORY_THRESHOLD_KB) ? 1 : 0;
  59   }
  60   *aResult = (sLowMemory == 1);
  61 #else
  62   *aResult = false;
  63 #endif
  64   return NS_OK;
  65 }
  66
  67 /*static*/
  68 nsresult nsMemoryImpl::Create(nsISupports* aOuter, const nsIID& aIID,
  69                               void** aResult) {
  70   if (NS_WARN_IF(aOuter)) {
  71     return NS_ERROR_NO_AGGREGATION;
  72   }
  73   return sGlobalMemory.QueryInterface(aIID, aResult);
  74 }
  75
  76 nsresult nsMemoryImpl::FlushMemory(const char16_t* aReason, bool aImmediate) {
  77   if (aImmediate) {
  78     // They've asked us to run the flusher *immediately*. We've
  79     // got to be on the UI main thread for us to be able to do
  80     // that...are we?
  81     if (!NS_IsMainThread()) {
  82       NS_ERROR("can't synchronously flush memory: not on UI thread");
  83       return NS_ERROR_FAILURE;
  84     }
  85   }
  86
  87   bool lastVal = sIsFlushing.exchange(true);
  88   if (lastVal) {
  89     return NS_OK;
  90   }
  91
  92   PRIntervalTime now = PR_IntervalNow();
  93
  94   // Run the flushers immediately if we can; otherwise, proxy to the
  95   // UI thread and run 'em asynchronously.
  96   nsresult rv = NS_OK;
  97   if (aImmediate) {
  98     RunFlushers(aReason);
  99   } else {
 100     // Don't broadcast more than once every 1000ms to avoid being noisy
 101     if (PR_IntervalToMicroseconds(now - sLastFlushTime) > 1000) {
 102       sFlushEvent.mReason = aReason;
 103       rv = NS_DispatchToMainThread(&sFlushEvent);
 104     }
 105   }
 106
 107   sLastFlushTime = now;
 108   return rv;
 109 }
 110
 111 void nsMemoryImpl::RunFlushers(const char16_t* aReason) {
 112   nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
 113   if (os) {
 114     // Instead of:
 115     //  os->NotifyObservers(this, "memory-pressure", aReason);
 116     // we are going to do this manually to see who/what is
 117     // deallocating.
 118
 119     nsCOMPtr<nsISimpleEnumerator> e;
 120     os->EnumerateObservers("memory-pressure", getter_AddRefs(e));
 121
 122     if (e) {
 123       nsCOMPtr<nsIObserver> observer;
 124       bool loop = true;
 125
 126       while (NS_SUCCEEDED(e->HasMoreElements(&loop)) && loop) {
 127         nsCOMPtr<nsISupports> supports;
 128         e->GetNext(getter_AddRefs(supports));
 129
 130         if (!supports) {
 131           continue;
 132         }
 133
 134         observer = do_QueryInterface(supports);
 135         observer->Observe(observer, "memory-pressure", aReason);
 136       }
 137     }
 138   }
 139
 140   sIsFlushing = false;
 141 }
 142
 143 // XXX need NS_IMPL_STATIC_ADDREF/RELEASE
 144 NS_IMETHODIMP_(MozExternalRefCountType)
 145 nsMemoryImpl::FlushEvent::AddRef() { return 2; }
 146 NS_IMETHODIMP_(MozExternalRefCountType)
 147 nsMemoryImpl::FlushEvent::Release() { return 1; }
 148 NS_IMPL_QUERY_INTERFACE(nsMemoryImpl::FlushEvent, nsIRunnable)
 149
 150 NS_IMETHODIMP
 151 nsMemoryImpl::FlushEvent::Run() {
 152   sGlobalMemory.RunFlushers(mReason);
 153   return NS_OK;
 154 }
 155
 156 mozilla::Atomic<bool> nsMemoryImpl::sIsFlushing;
 157
 158 PRIntervalTime nsMemoryImpl::sLastFlushTime = 0;
 159
 160 nsMemoryImpl::FlushEvent nsMemoryImpl::sFlushEvent;
 161
 162 nsresult NS_GetMemoryManager(nsIMemory** aResult) {
 163   return sGlobalMemory.QueryInterface(NS_GET_IID(nsIMemory), (void**)aResult);
 164 }