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// Copyright 2015 The Chromium Authors
// 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"
#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:
NativeLibraryPrefetcher() = delete;
NativeLibraryPrefetcher(const NativeLibraryPrefetcher&) = delete;
NativeLibraryPrefetcher& operator=(const NativeLibraryPrefetcher&) = delete;
// 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();
// Calls madvise() on the native library executable so that residency
// collection is accurate.
static void MadviseForResidencyCollection();
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);
};
} // namespace android
} // namespace base
#endif // BUILDFLAG(SUPPORTS_CODE_ORDERING)
#endif // BASE_ANDROID_LIBRARY_LOADER_LIBRARY_PREFETCHER_H_
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