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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
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_AvailableMemoryWatcherUtils_h
#define mozilla_AvailableMemoryWatcherUtils_h
#include "mozilla/Attributes.h"
#include "nsISupportsUtils.h" // For nsresult
namespace mozilla {
struct MemoryInfo {
unsigned long memTotal;
unsigned long memAvailable;
};
// Check /proc/meminfo for low memory. Largely C method for reading
// /proc/meminfo.
MOZ_MAYBE_UNUSED
static nsresult ReadMemoryFile(const char* meminfoPath, MemoryInfo& aResult) {
FILE* fd;
if ((fd = fopen(meminfoPath, "r")) == nullptr) {
// Meminfo somehow unreachable
return NS_ERROR_FAILURE;
}
char buff[128];
/* The first few lines of meminfo look something like this:
* MemTotal: 65663448 kB
* MemFree: 57368112 kB
* MemAvailable: 61852700 kB
* We mostly care about the available versus the total. We calculate our
* memory thresholds using this, and when memory drops below 5% we consider
* this to be a memory pressure event. In practice these lines aren't
* necessarily in order, but we can simply search for MemTotal
* and MemAvailable.
*/
char namebuffer[20];
while ((fgets(buff, sizeof(buff), fd)) != nullptr) {
if (strstr(buff, "MemTotal:")) {
sscanf(buff, "%s %lu ", namebuffer, &aResult.memTotal);
}
if (strstr(buff, "MemAvailable:")) {
sscanf(buff, "%s %lu ", namebuffer, &aResult.memAvailable);
}
}
fclose(fd);
return NS_OK;
}
} // namespace mozilla
#endif // ifndef mozilla_AvailableMemoryWatcherUtils_h
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