1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.internal.util;
18
19import java.io.FileInputStream;
20
21import android.os.StrictMode;
22
23public class MemInfoReader {
24    byte[] mBuffer = new byte[1024];
25
26    private long mTotalSize;
27    private long mFreeSize;
28    private long mCachedSize;
29
30    private boolean matchText(byte[] buffer, int index, String text) {
31        int N = text.length();
32        if ((index+N) >= buffer.length) {
33            return false;
34        }
35        for (int i=0; i<N; i++) {
36            if (buffer[index+i] != text.charAt(i)) {
37                return false;
38            }
39        }
40        return true;
41    }
42
43    private long extractMemValue(byte[] buffer, int index) {
44        while (index < buffer.length && buffer[index] != '\n') {
45            if (buffer[index] >= '0' && buffer[index] <= '9') {
46                int start = index;
47                index++;
48                while (index < buffer.length && buffer[index] >= '0'
49                    && buffer[index] <= '9') {
50                    index++;
51                }
52                String str = new String(buffer, 0, start, index-start);
53                return ((long)Integer.parseInt(str)) * 1024;
54            }
55            index++;
56        }
57        return 0;
58    }
59
60    public void readMemInfo() {
61        // Permit disk reads here, as /proc/meminfo isn't really "on
62        // disk" and should be fast.  TODO: make BlockGuard ignore
63        // /proc/ and /sys/ files perhaps?
64        StrictMode.ThreadPolicy savedPolicy = StrictMode.allowThreadDiskReads();
65        try {
66            mTotalSize = 0;
67            mFreeSize = 0;
68            mCachedSize = 0;
69            FileInputStream is = new FileInputStream("/proc/meminfo");
70            int len = is.read(mBuffer);
71            is.close();
72            final int BUFLEN = mBuffer.length;
73            int count = 0;
74            for (int i=0; i<len && count < 3; i++) {
75                if (matchText(mBuffer, i, "MemTotal")) {
76                    i += 8;
77                    mTotalSize = extractMemValue(mBuffer, i);
78                    count++;
79                } else if (matchText(mBuffer, i, "MemFree")) {
80                    i += 7;
81                    mFreeSize = extractMemValue(mBuffer, i);
82                    count++;
83                } else if (matchText(mBuffer, i, "Cached")) {
84                    i += 6;
85                    mCachedSize = extractMemValue(mBuffer, i);
86                    count++;
87                }
88                while (i < BUFLEN && mBuffer[i] != '\n') {
89                    i++;
90                }
91            }
92        } catch (java.io.FileNotFoundException e) {
93        } catch (java.io.IOException e) {
94        } finally {
95            StrictMode.setThreadPolicy(savedPolicy);
96        }
97    }
98
99    public long getTotalSize() {
100        return mTotalSize;
101    }
102
103    public long getFreeSize() {
104        return mFreeSize;
105    }
106
107    public long getCachedSize() {
108        return mCachedSize;
109    }
110}
111