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// 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 <string>
#include "base/debug/proc_maps_linux.h"
#include "base/gtest_prod_util.h"
#include "base/macros.h"
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 the parsing. If the parsing
// returns an incorrect address, only the forked process will crash.
// - 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 ranges matching the native library, forks a low priority
// process pre-fetching these ranges and wait()s for it.
// Returns true for success.
static bool ForkAndPrefetchNativeLibrary();
// Returns the percentage of the native library code currently resident in
// memory, or -1 in case of error.
static int PercentageOfResidentNativeLibraryCode();
private:
using AddressRange = std::pair<uintptr_t, uintptr_t>;
// Returns true if the region matches native code or data.
static bool IsGoodToPrefetch(const base::debug::MappedMemoryRegion& region);
// Filters the regions to keep only libchrome ranges if possible.
static void FilterLibchromeRangesOnlyIfPossible(
const std::vector<base::debug::MappedMemoryRegion>& regions,
std::vector<AddressRange>* ranges);
// Finds the ranges matching the native library in /proc/self/maps.
// Returns true for success.
static bool FindRanges(std::vector<AddressRange>* ranges);
// Returns the percentage of the given address ranges currently resident in
// memory, or -1 in case of error.
static int PercentageOfResidentCode(const std::vector<AddressRange>& ranges);
FRIEND_TEST_ALL_PREFIXES(NativeLibraryPrefetcherTest,
TestIsGoodToPrefetchNoRange);
FRIEND_TEST_ALL_PREFIXES(NativeLibraryPrefetcherTest,
TestIsGoodToPrefetchUnreadableRange);
FRIEND_TEST_ALL_PREFIXES(NativeLibraryPrefetcherTest,
TestIsGoodToPrefetchSkipSharedRange);
FRIEND_TEST_ALL_PREFIXES(NativeLibraryPrefetcherTest,
TestIsGoodToPrefetchLibchromeRange);
FRIEND_TEST_ALL_PREFIXES(NativeLibraryPrefetcherTest,
TestIsGoodToPrefetchBaseApkRange);
FRIEND_TEST_ALL_PREFIXES(NativeLibraryPrefetcherTest,
TestFilterLibchromeRangesOnlyIfPossibleNoLibchrome);
FRIEND_TEST_ALL_PREFIXES(NativeLibraryPrefetcherTest,
TestFilterLibchromeRangesOnlyIfPossibleHasLibchrome);
FRIEND_TEST_ALL_PREFIXES(NativeLibraryPrefetcherTest,
TestPercentageOfResidentCode);
FRIEND_TEST_ALL_PREFIXES(NativeLibraryPrefetcherTest,
TestPercentageOfResidentCodeTwoRegions);
DISALLOW_IMPLICIT_CONSTRUCTORS(NativeLibraryPrefetcher);
};
} // namespace android
} // namespace base
#endif // BASE_ANDROID_LIBRARY_LOADER_LIBRARY_PREFETCHER_H_