1 files changed, 66 insertions, 0 deletions
diff --git a/base/android/library_loader/library_prefetcher.h b/base/android/library_loader/library_prefetcher.h
new file mode 100644
index 0000000000..29f294ef62
--- /dev/null
+++ b/base/android/library_loader/library_prefetcher.h
@@ -0,0 +1,66 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_ANDROID_LIBRARY_LOADER_LIBRARY_PREFETCHER_H_
+#define BASE_ANDROID_LIBRARY_LOADER_LIBRARY_PREFETCHER_H_
+
+#include <jni.h>
+
+#include <stdint.h>
+
+#include "base/android/library_loader/anchor_functions_buildflags.h"
+#include "base/base_export.h"
+#include "base/gtest_prod_util.h"
+#include "base/macros.h"
+
+#if BUILDFLAG(SUPPORTS_CODE_ORDERING)
+
+namespace base {
+namespace android {
+
+// Forks and waits for a process prefetching the native library. This is done in
+// a forked process for the following reasons:
+// - Isolating the main process from mistakes in getting the address range, only
+//   crashing the forked process in case of mistake.
+// - Not inflating the memory used by the main process uselessly, which could
+//   increase its likelihood to be killed.
+// The forked process has background priority and, since it is not declared to
+// the Android runtime, can be killed at any time, which is not an issue here.
+class BASE_EXPORT NativeLibraryPrefetcher {
+ public:
+  // Finds the executable code range, forks a low priority process pre-fetching
+  // it wait()s for the process to exit or die. If ordered_only is true, only
+  // the ordered section is prefetched. See GetOrdrderedTextRange() in
+  // library_prefetcher.cc.
+  static void ForkAndPrefetchNativeLibrary(bool ordered_only);
+
+  // Returns the percentage of the native library code currently resident in
+  // memory, or -1 in case of error.
+  static int PercentageOfResidentNativeLibraryCode();
+
+  // Collects residency for the native library executable multiple times, then
+  // dumps it to disk.
+  static void PeriodicallyCollectResidency();
+
+  // Calls madvise() on the native library executable, using orderfile
+  // information to decide how to advise each part of the library.
+  static void MadviseForOrderfile();
+
+ private:
+  // Returns the percentage of [start, end] currently resident in
+  // memory, or -1 in case of error.
+  static int PercentageOfResidentCode(size_t start, size_t end);
+
+  FRIEND_TEST_ALL_PREFIXES(NativeLibraryPrefetcherTest,
+                           TestPercentageOfResidentCode);
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(NativeLibraryPrefetcher);
+};
+
+}  // namespace android
+}  // namespace base
+
+#endif  // BUILDFLAG(SUPPORTS_CODE_ORDERING)
+
+#endif  // BASE_ANDROID_LIBRARY_LOADER_LIBRARY_PREFETCHER_H_