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-rw-r--r--xpcom/base/AvailableMemoryWatcherUtils.h56
1 files changed, 56 insertions, 0 deletions
diff --git a/xpcom/base/AvailableMemoryWatcherUtils.h b/xpcom/base/AvailableMemoryWatcherUtils.h
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+++ b/xpcom/base/AvailableMemoryWatcherUtils.h
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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