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| 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 package org.chromium.base; |
| 6 |
| 7 // The only purpose of this class is to allow sending CPU properties |
| 8 // from the browser process to sandboxed renderer processes. This is |
| 9 // needed because sandboxed processes cannot, on ARM, query the kernel |
| 10 // about the CPU's properties by parsing /proc, so this operation must |
| 11 // be performed in the browser process, and the result passed to |
| 12 // renderer ones. |
| 13 // |
| 14 // For more context, see crbug.com/164154 |
| 15 // |
| 16 // Technically, this is a wrapper around the native NDK cpufeatures |
| 17 // library. The exact CPU features bits are never used in Java so |
| 18 // there is no point in duplicating their definitions here. |
| 19 // |
| 20 @JNINamespace("base::android") |
| 21 public abstract class CpuFeatures { |
| 22 /** |
| 23 * Return the number of CPU Cores on the device. |
| 24 */ |
| 25 public static int getCount() { |
| 26 return nativeGetCoreCount(); |
| 27 } |
| 28 |
| 29 /** |
| 30 * Return the CPU feature mask. |
| 31 * This is a 64-bit integer that corresponds to the CPU's features. |
| 32 * The value is taken directory to |
| 33 */ |
| 34 public static long getMask() { |
| 35 return nativeGetCpuFeatures(); |
| 36 } |
| 37 |
| 38 /** |
| 39 * Set CPU core count and feature mask. |
| 40 * This must be called in sandboxed renderer processes before any |
| 41 * other function from the native library that might depend on the |
| 42 * the CPU count / features. |
| 43 * @param coreCount Number of CPU cores on device. |
| 44 * @param featuresMask CPU features mask. |
| 45 */ |
| 46 public static void set(int coreCount, long featuresMask) { |
| 47 nativeSetCpu(coreCount, featuresMask); |
| 48 } |
| 49 |
| 50 private static native int nativeGetCoreCount(); |
| 51 private static native long nativeGetCpuFeatures(); |
| 52 private static native void nativeSetCpu(int coreCount, long featuresMask); |
| 53 } |
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