1 /*
2  * Copyright (C) 2018 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 
17 package com.android.server.am;
18 
19 import static com.android.server.am.ActivityManagerDebugConfig.DEBUG_METRICS;
20 import static com.android.server.am.ActivityManagerDebugConfig.TAG_AM;
21 import static com.android.server.am.ActivityManagerDebugConfig.TAG_WITH_CLASS_NAME;
22 
23 import android.annotation.Nullable;
24 import android.os.FileUtils;
25 import android.util.Slog;
26 
27 import com.android.internal.annotations.VisibleForTesting;
28 
29 import java.io.File;
30 import java.io.IOException;
31 import java.util.Locale;
32 import java.util.regex.Matcher;
33 import java.util.regex.Pattern;
34 
35 /**
36  * Static utility methods related to {@link MemoryStat}.
37  */
38 final class MemoryStatUtil {
39     private static final String TAG = TAG_WITH_CLASS_NAME ? "MemoryStatUtil" : TAG_AM;
40 
41     /** Path to check if device has memcg */
42     private static final String MEMCG_TEST_PATH = "/dev/memcg/apps/memory.stat";
43     /** Path to memory stat file for logging app start memory state */
44     private static final String MEMORY_STAT_FILE_FMT = "/dev/memcg/apps/uid_%d/pid_%d/memory.stat";
45     /** Path to procfs stat file for logging app start memory state */
46     private static final String PROC_STAT_FILE_FMT = "/proc/%d/stat";
47 
48     private static final Pattern PGFAULT = Pattern.compile("total_pgfault (\\d+)");
49     private static final Pattern PGMAJFAULT = Pattern.compile("total_pgmajfault (\\d+)");
50     private static final Pattern RSS_IN_BYTES = Pattern.compile("total_rss (\\d+)");
51     private static final Pattern CACHE_IN_BYTES = Pattern.compile("total_cache (\\d+)");
52     private static final Pattern SWAP_IN_BYTES = Pattern.compile("total_swap (\\d+)");
53 
54     private static final int PGFAULT_INDEX = 9;
55     private static final int PGMAJFAULT_INDEX = 11;
56     private static final int RSS_IN_BYTES_INDEX = 23;
57 
58     /** True if device has memcg */
59     private static volatile Boolean sDeviceHasMemCg;
60 
MemoryStatUtil()61     private MemoryStatUtil() {}
62 
63     /**
64      * Reads memory stat for a process.
65      *
66      * Reads from memcg if available on device, else fallback to procfs.
67      * Returns null if no stats can be read.
68      */
69     @Nullable
readMemoryStatFromFilesystem(int uid, int pid)70     static MemoryStat readMemoryStatFromFilesystem(int uid, int pid) {
71         return hasMemcg() ? readMemoryStatFromMemcg(uid, pid) : readMemoryStatFromProcfs(pid);
72     }
73 
74     /**
75      * Reads memory.stat of a process from memcg.
76      *
77      * Returns null if file is not found in memcg or if file has unrecognized contents.
78      */
79     @Nullable
readMemoryStatFromMemcg(int uid, int pid)80     static MemoryStat readMemoryStatFromMemcg(int uid, int pid) {
81         final String path = String.format(Locale.US, MEMORY_STAT_FILE_FMT, uid, pid);
82         return parseMemoryStatFromMemcg(readFileContents(path));
83     }
84 
85     /**
86      * Reads memory stat of a process from procfs.
87      *
88      * Returns null if file is not found in procfs or if file has unrecognized contents.
89      */
90     @Nullable
readMemoryStatFromProcfs(int pid)91     static MemoryStat readMemoryStatFromProcfs(int pid) {
92         final String path = String.format(Locale.US, PROC_STAT_FILE_FMT, pid);
93         return parseMemoryStatFromProcfs(readFileContents(path));
94     }
95 
readFileContents(String path)96     private static String readFileContents(String path) {
97         final File file = new File(path);
98         if (!file.exists()) {
99             if (DEBUG_METRICS) Slog.i(TAG, path + " not found");
100             return null;
101         }
102 
103         try {
104             return FileUtils.readTextFile(file, 0 /* max */, null /* ellipsis */);
105         } catch (IOException e) {
106             Slog.e(TAG, "Failed to read file:", e);
107             return null;
108         }
109     }
110 
111     /**
112      * Parses relevant statistics out from the contents of a memory.stat file in memcg.
113      */
114     @VisibleForTesting(visibility = VisibleForTesting.Visibility.PRIVATE)
115     @Nullable
parseMemoryStatFromMemcg(String memoryStatContents)116     static MemoryStat parseMemoryStatFromMemcg(String memoryStatContents) {
117         if (memoryStatContents == null || memoryStatContents.isEmpty()) {
118             return null;
119         }
120 
121         final MemoryStat memoryStat = new MemoryStat();
122         Matcher m;
123         m = PGFAULT.matcher(memoryStatContents);
124         memoryStat.pgfault = m.find() ? Long.valueOf(m.group(1)) : 0;
125         m = PGMAJFAULT.matcher(memoryStatContents);
126         memoryStat.pgmajfault = m.find() ? Long.valueOf(m.group(1)) : 0;
127         m = RSS_IN_BYTES.matcher(memoryStatContents);
128         memoryStat.rssInBytes = m.find() ? Long.valueOf(m.group(1)) : 0;
129         m = CACHE_IN_BYTES.matcher(memoryStatContents);
130         memoryStat.cacheInBytes = m.find() ? Long.valueOf(m.group(1)) : 0;
131         m = SWAP_IN_BYTES.matcher(memoryStatContents);
132         memoryStat.swapInBytes = m.find() ? Long.valueOf(m.group(1)) : 0;
133         return memoryStat;
134     }
135 
136     /**
137      * Parses relevant statistics out from the contents of a /proc/pid/stat file in procfs.
138      */
139     @VisibleForTesting(visibility = VisibleForTesting.Visibility.PRIVATE)
140     @Nullable
parseMemoryStatFromProcfs(String procStatContents)141     static MemoryStat parseMemoryStatFromProcfs(String procStatContents) {
142         if (procStatContents == null || procStatContents.isEmpty()) {
143             return null;
144         }
145 
146         final String[] splits = procStatContents.split(" ");
147         if (splits.length < 24) {
148             return null;
149         }
150 
151         final MemoryStat memoryStat = new MemoryStat();
152         memoryStat.pgfault = Long.valueOf(splits[PGFAULT_INDEX]);
153         memoryStat.pgmajfault = Long.valueOf(splits[PGMAJFAULT_INDEX]);
154         memoryStat.rssInBytes = Long.valueOf(splits[RSS_IN_BYTES_INDEX]);
155         return memoryStat;
156     }
157 
158     /**
159      * Checks if memcg is available on device.
160      *
161      * Touches the filesystem to do the check.
162      */
hasMemcg()163     static boolean hasMemcg() {
164         if (sDeviceHasMemCg == null) {
165             sDeviceHasMemCg = (new File(MEMCG_TEST_PATH)).exists();
166         }
167         return sDeviceHasMemCg;
168     }
169 
170     static final class MemoryStat {
171         /** Number of page faults */
172         long pgfault;
173         /** Number of major page faults */
174         long pgmajfault;
175         /** Number of bytes of anonymous and swap cache memory */
176         long rssInBytes;
177         /** Number of bytes of page cache memory */
178         long cacheInBytes;
179         /** Number of bytes of swap usage */
180         long swapInBytes;
181     }
182 }
183