Prefetch the native library from native code by parsing /proc/pid/maps.

base/android/library_loader/library_prefetcher.h

Index: base/android/library_loader/library_prefetcher.h
diff --git a/base/android/library_loader/library_prefetcher.h b/base/android/library_loader/library_prefetcher.h
new file mode 100644
index 0000000000000000000000000000000000000000..23973e400bdb7ec7b6a92098a86346912316e28a
--- /dev/null
+++ b/base/android/library_loader/library_prefetcher.h
@@ -0,0 +1,57 @@
+// 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"
+
+namespace base {
+namespace android {
+
+class NativeLibraryPrefetcher {
+ public:
+  // Finds the ranges matching the native library, forks a low priority
+  // process pre-fetching these ranges and wait()s for it.
+  // Returns false on error.
+  static bool ForkAndPrefetchNativeLibrary();
+
+ 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 TakeOnlyLibchromeRangesIfPossible(
+      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);
+
+  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,
+                           TestTakeOnlyLibchromeRangesIfPossibleNoLibchrome);
+  FRIEND_TEST_ALL_PREFIXES(NativeLibraryPrefetcherTest,
+                           TestTakeOnlyLibchromeRangesIfPossibleHasLibchrome);
+};

[Robert Sesek, 2015/04/02 19:46:48]

DISALLOW_IMPLICIT_CONSTRUCTORS() to prevent instantiation.

[Benoit L, 2015/04/03 09:47:16]

Done.

+
+}  // namespace android
+}  // namespace base
+
+#endif  // BASE_ANDROID_LIBRARY_LOADER_LIBRARY_PREFETCHER_H_