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/* -*- 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
#include "nsMemory.h"
#include "nsThreadUtils.h"
#include "nsIObserver.h"
#include "nsIObserverService.h"
#include "nsIRunnable.h"
#include "nsISimpleEnumerator.h"
#include "nsCOMPtr.h"
#include "mozilla/Services.h"
#include "mozilla/Atomics.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 HardwareUtils.java
# define LOW_MEMORY_THRESHOLD_KB (384 * 1024)
#endif
static mozilla::Atomic<bool> sIsFlushing;
static PRIntervalTime sLastFlushTime = 0;
// static
bool nsMemory::IsLowMemoryPlatform() {
#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
// check if MemTotal from /proc/meminfo is less than LOW_MEMORY_THRESHOLD_KB
FILE* fd = fopen("/proc/meminfo", "r");
if (!fd) {
return false;
}
uint64_t mem = 0;
int rv = fscanf(fd, "MemTotal: %" PRIu64 " kB", &mem);
if (fclose(fd)) {
return false;
}
if (rv != 1) {
return false;
}
sLowMemory = (mem < LOW_MEMORY_THRESHOLD_KB) ? 1 : 0;
}
return (sLowMemory == 1);
#else
return false;
#endif
}
static void 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;
}
static nsresult FlushMemory(const char16_t* aReason, bool aImmediate) {
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 and run 'em asynchronously.
nsresult rv = NS_OK;
if (aImmediate) {
RunFlushers(aReason);
} else {
// Don't broadcast more than once every 1000ms to avoid being noisy
if (PR_IntervalToMicroseconds(now - sLastFlushTime) > 1000) {
nsCOMPtr<nsIRunnable> runnable(NS_NewRunnableFunction(
"FlushMemory",
[reason = aReason]() -> void { RunFlushers(reason); }));
NS_DispatchToMainThread(runnable.forget());
}
}
sLastFlushTime = now;
return rv;
}
nsresult nsMemory::HeapMinimize(bool aImmediate) {
return FlushMemory(u"heap-minimize", aImmediate);
}