content: /*
   * Copyright (C) 2018 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.android.server.am;
  
  import static com.android.server.am.ActivityManagerDebugConfig.TAG_AM;
  import static com.android.server.am.ActivityManagerDebugConfig.TAG_WITH_CLASS_NAME;
  import static com.android.server.wm.ActivityTaskManagerDebugConfig.DEBUG_METRICS;
  
  import android.annotation.Nullable;
  import android.os.FileUtils;
  import android.os.SystemProperties;
  import android.system.Os;
  import android.system.OsConstants;
  import android.util.Slog;
  import android.util.SparseArray;
  
  import com.android.internal.annotations.VisibleForTesting;
  
  import java.io.File;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.Locale;
  import java.util.Objects;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * Static utility methods related to {@link MemoryStat}.
   */
  public final class MemoryStatUtil {
      static final int BYTES_IN_KILOBYTE = 1024;
      static final long JIFFY_NANOS = 1_000_000_000 / Os.sysconf(OsConstants._SC_CLK_TCK);
  
      private static final String TAG = TAG_WITH_CLASS_NAME ? "MemoryStatUtil" : TAG_AM;
  
      /** True if device has per-app memcg */
      private static final boolean DEVICE_HAS_PER_APP_MEMCG =
              SystemProperties.getBoolean("ro.config.per_app_memcg", false);
  
      /** Path to memory stat file for logging app start memory state */
      private static final String MEMORY_STAT_FILE_FMT = "/dev/memcg/apps/uid_%d/pid_%d/memory.stat";
      /** Path to procfs stat file for logging app start memory state */
      private static final String PROC_STAT_FILE_FMT = "/proc/%d/stat";
      /** Path to procfs status file for logging app memory state */
      private static final String PROC_STATUS_FILE_FMT = "/proc/%d/status";
      /** Path to procfs cmdline file. Used with pid: /proc/pid/cmdline. */
      private static final String PROC_CMDLINE_FILE_FMT = "/proc/%d/cmdline";
      /** Path to debugfs file for the system ion heap. */
      private static final String DEBUG_SYSTEM_ION_HEAP_FILE = "/sys/kernel/debug/ion/heaps/system";
  
      private static final Pattern PGFAULT = Pattern.compile("total_pgfault (\\d+)");
      private static final Pattern PGMAJFAULT = Pattern.compile("total_pgmajfault (\\d+)");
      private static final Pattern RSS_IN_BYTES = Pattern.compile("total_rss (\\d+)");
      private static final Pattern CACHE_IN_BYTES = Pattern.compile("total_cache (\\d+)");
      private static final Pattern SWAP_IN_BYTES = Pattern.compile("total_swap (\\d+)");
  
      private static final Pattern RSS_HIGH_WATERMARK_IN_KILOBYTES =
              Pattern.compile("VmHWM:\\s*(\\d+)\\s*kB");
      private static final Pattern PROCFS_RSS_IN_KILOBYTES =
              Pattern.compile("VmRSS:\\s*(\\d+)\\s*kB");
      private static final Pattern PROCFS_ANON_RSS_IN_KILOBYTES =
              Pattern.compile("RssAnon:\\s*(\\d+)\\s*kB");
      private static final Pattern PROCFS_SWAP_IN_KILOBYTES =
              Pattern.compile("VmSwap:\\s*(\\d+)\\s*kB");
  
      private static final Pattern ION_HEAP_SIZE_IN_BYTES =
              Pattern.compile("\n\\s*total\\s*(\\d+)\\s*\n");
      private static final Pattern PROCESS_ION_HEAP_SIZE_IN_BYTES =
              Pattern.compile("\n\\s+\\S+\\s+(\\d+)\\s+(\\d+)");
  
      private static final int PGFAULT_INDEX = 9;
      private static final int PGMAJFAULT_INDEX = 11;
      private static final int START_TIME_INDEX = 21;
  
      private MemoryStatUtil() {}
  
      /**
       * Reads memory stat for a process.
       *
       * Reads from per-app memcg if available on device, else fallback to procfs.
       * Returns null if no stats can be read.
       */
      @Nullable
      public static MemoryStat readMemoryStatFromFilesystem(int uid, int pid) {
          return hasMemcg() ? readMemoryStatFromMemcg(uid, pid) : readMemoryStatFromProcfs(pid);
      }
  
      /**
       * Reads memory.stat of a process from memcg.
       *
       * Returns null if file is not found in memcg or if file has unrecognized contents.
       */
      @Nullable
      static MemoryStat readMemoryStatFromMemcg(int uid, int pid) {
          final String statPath = String.format(Locale.US, MEMORY_STAT_FILE_FMT, uid, pid);
          return parseMemoryStatFromMemcg(readFileContents(statPath));
      }
  
      /**
       * Reads memory stat of a process from procfs.
       *
       * Returns null if file is not found in procfs or if file has unrecognized contents.
       */
      @Nullable
      public static MemoryStat readMemoryStatFromProcfs(int pid) {
          final String statPath = String.format(Locale.US, PROC_STAT_FILE_FMT, pid);
          final String statusPath = String.format(Locale.US, PROC_STATUS_FILE_FMT, pid);
          return parseMemoryStatFromProcfs(readFileContents(statPath), readFileContents(statusPath));
      }
  
      /**
       * Reads RSS high-water mark of a process from procfs. Returns value of the VmHWM field in
       * /proc/PID/status in bytes or 0 if not available.
       */
      public static long readRssHighWaterMarkFromProcfs(int pid) {
          final String statusPath = String.format(Locale.US, PROC_STATUS_FILE_FMT, pid);
          return parseVmHWMFromProcfs(readFileContents(statusPath));
      }
  
      /**
       * Reads cmdline of a process from procfs.
       *
       * Returns content of /proc/pid/cmdline (e.g. /system/bin/statsd) or an empty string
       * if the file is not available.
       */
      public static String readCmdlineFromProcfs(int pid) {
          final String path = String.format(Locale.US, PROC_CMDLINE_FILE_FMT, pid);
          return parseCmdlineFromProcfs(readFileContents(path));
      }
  
      /**
       * Reads size of the system ion heap from debugfs.
       *
       * Returns value of the total size in bytes of the system ion heap from
       * /sys/kernel/debug/ion/heaps/system.
       */
      public static long readSystemIonHeapSizeFromDebugfs() {
          return parseIonHeapSizeFromDebugfs(readFileContents(DEBUG_SYSTEM_ION_HEAP_FILE));
      }
  
      /**
       * Reads process allocation sizes on the system ion heap from debugfs.
       *
       * Returns values of allocation sizes in bytes on the system ion heap from
       * /sys/kernel/debug/ion/heaps/system.
       */
      public static List<IonAllocations> readProcessSystemIonHeapSizesFromDebugfs() {
          return parseProcessIonHeapSizesFromDebugfs(readFileContents(DEBUG_SYSTEM_ION_HEAP_FILE));
      }
  
      private static String readFileContents(String path) {
          final File file = new File(path);
          if (!file.exists()) {
              if (DEBUG_METRICS) Slog.i(TAG, path + " not found");
              return null;
          }
  
          try {
              return FileUtils.readTextFile(file, 0 /* max */, null /* ellipsis */);
          } catch (IOException e) {
              Slog.e(TAG, "Failed to read file:", e);
              return null;
          }
      }
  
      /**
       * Parses relevant statistics out from the contents of a memory.stat file in memcg.
       */
      @VisibleForTesting
      @Nullable
      static MemoryStat parseMemoryStatFromMemcg(String memoryStatContents) {
          if (memoryStatContents == null || memoryStatContents.isEmpty()) {
              return null;
          }
  
          final MemoryStat memoryStat = new MemoryStat();
          memoryStat.pgfault = tryParseLong(PGFAULT, memoryStatContents);
          memoryStat.pgmajfault = tryParseLong(PGMAJFAULT, memoryStatContents);
          memoryStat.rssInBytes = tryParseLong(RSS_IN_BYTES, memoryStatContents);
          memoryStat.cacheInBytes = tryParseLong(CACHE_IN_BYTES, memoryStatContents);
          memoryStat.swapInBytes = tryParseLong(SWAP_IN_BYTES, memoryStatContents);
          return memoryStat;
      }
  
      /**
       * Parses relevant statistics out from the contents of the /proc/pid/stat file in procfs.
       */
      @VisibleForTesting
      @Nullable
      static MemoryStat parseMemoryStatFromProcfs(
              String procStatContents, String procStatusContents) {
          if (procStatContents == null || procStatContents.isEmpty()) {
              return null;
          }
          if (procStatusContents == null || procStatusContents.isEmpty()) {
              return null;
          }
  
          final String[] splits = procStatContents.split(" ");
          if (splits.length < 24) {
              return null;
          }
  
          try {
              final MemoryStat memoryStat = new MemoryStat();
              memoryStat.pgfault = Long.parseLong(splits[PGFAULT_INDEX]);
              memoryStat.pgmajfault = Long.parseLong(splits[PGMAJFAULT_INDEX]);
              memoryStat.rssInBytes =
                  tryParseLong(PROCFS_RSS_IN_KILOBYTES, procStatusContents) * BYTES_IN_KILOBYTE;
              memoryStat.anonRssInBytes =
                  tryParseLong(PROCFS_ANON_RSS_IN_KILOBYTES, procStatusContents) * BYTES_IN_KILOBYTE;
              memoryStat.swapInBytes =
                  tryParseLong(PROCFS_SWAP_IN_KILOBYTES, procStatusContents) * BYTES_IN_KILOBYTE;
              memoryStat.startTimeNanos = Long.parseLong(splits[START_TIME_INDEX]) * JIFFY_NANOS;
              return memoryStat;
          } catch (NumberFormatException e) {
              Slog.e(TAG, "Failed to parse value", e);
              return null;
          }
      }
  
      /**
       * Parses RSS high watermark out from the contents of the /proc/pid/status file in procfs. The
       * returned value is in bytes.
       */
      @VisibleForTesting
      static long parseVmHWMFromProcfs(String procStatusContents) {
          if (procStatusContents == null || procStatusContents.isEmpty()) {
              return 0;
          }
          // Convert value read from /proc/pid/status from kilobytes to bytes.
          return tryParseLong(RSS_HIGH_WATERMARK_IN_KILOBYTES, procStatusContents)
                  * BYTES_IN_KILOBYTE;
      }
  
  
      /**
       * Parses cmdline out of the contents of the /proc/pid/cmdline file in procfs.
       *
       * Parsing is required to strip anything after first null byte.
       */
      @VisibleForTesting
      static String parseCmdlineFromProcfs(String cmdline) {
          if (cmdline == null) {
              return "";
          }
          int firstNullByte = cmdline.indexOf("\0");
          if (firstNullByte == -1) {
              return cmdline;
          }
          return cmdline.substring(0, firstNullByte);
      }
  
      /**
       * Parses the ion heap size from the contents of a file under /sys/kernel/debug/ion/heaps in
       * debugfs. The returned value is in bytes.
       */
      @VisibleForTesting
      static long parseIonHeapSizeFromDebugfs(String contents) {
          if (contents == null || contents.isEmpty()) {
              return 0;
          }
          return tryParseLong(ION_HEAP_SIZE_IN_BYTES, contents);
      }
  
      /**
       * Parses per-process allocation sizes on the ion heap from the contents of a file under
       * /sys/kernel/debug/ion/heaps in debugfs.
       */
      @VisibleForTesting
      static List<IonAllocations> parseProcessIonHeapSizesFromDebugfs(String contents) {
          if (contents == null || contents.isEmpty()) {
              return Collections.emptyList();
          }
  
          final Matcher m = PROCESS_ION_HEAP_SIZE_IN_BYTES.matcher(contents);
          final SparseArray<IonAllocations> entries = new SparseArray<>();
          while (m.find()) {
              try {
                  final int pid = Integer.parseInt(m.group(1));
                  final long sizeInBytes = Long.parseLong(m.group(2));
                  IonAllocations allocations = entries.get(pid);
                  if (allocations == null) {
                      allocations = new IonAllocations();
                      entries.put(pid, allocations);
                  }
                  allocations.pid = pid;
                  allocations.totalSizeInBytes += sizeInBytes;
                  allocations.count += 1;
                  allocations.maxSizeInBytes = Math.max(allocations.maxSizeInBytes, sizeInBytes);
              } catch (NumberFormatException e) {
                  Slog.e(TAG, "Failed to parse value", e);
              }
          }
  
          final List<IonAllocations> result = new ArrayList<>(entries.size());
          for (int i = 0; i < entries.size(); i++) {
              result.add(entries.valueAt(i));
          }
          return result;
      }
  
      /**
       * Returns whether per-app memcg is available on device.
       */
      static boolean hasMemcg() {
          return DEVICE_HAS_PER_APP_MEMCG;
      }
  
      /**
       * Parses a long from the input using the pattern. Returns 0 if the captured value is not
       * parsable. The pattern must have a single capturing group.
       */
      private static long tryParseLong(Pattern pattern, String input) {
          final Matcher m = pattern.matcher(input);
          try {
              return m.find() ? Long.parseLong(m.group(1)) : 0;
          } catch (NumberFormatException e) {
              Slog.e(TAG, "Failed to parse value", e);
              return 0;
          }
      }
  
      public static final class MemoryStat {
          /** Number of page faults */
          public long pgfault;
          /** Number of major page faults */
          public long pgmajfault;
          /** For memcg stats, the anon rss + swap cache size. Otherwise total RSS. */
          public long rssInBytes;
          /** Number of bytes of the anonymous RSS. Only present for non-memcg stats. */
          public long anonRssInBytes;
          /** Number of bytes of page cache memory. Only present for memcg stats. */
          public long cacheInBytes;
          /** Number of bytes of swap usage */
          public long swapInBytes;
          /** Device time when the processes started. */
          public long startTimeNanos;
      }
  
      /** Summary information about process ion allocations. */
      public static final class IonAllocations {
          /** PID these allocations belong to. */
          public int pid;
          /** Size of all individual allocations added together. */
          public long totalSizeInBytes;
          /** Number of allocations. */
          public int count;
          /** Size of the largest allocation. */
          public long maxSizeInBytes;
  
          @Override
          public boolean equals(Object o) {
              if (this == o) return true;
              if (o == null || getClass() != o.getClass()) return false;
              IonAllocations that = (IonAllocations) o;
              return pid == that.pid && totalSizeInBytes == that.totalSizeInBytes
                      && count == that.count && maxSizeInBytes == that.maxSizeInBytes;
          }
  
          @Override
          public int hashCode() {
              return Objects.hash(pid, totalSizeInBytes, count, maxSizeInBytes);
          }
  
          @Override
          public String toString() {
              return "IonAllocations{"
                      + "pid=" + pid
                      + ", totalSizeInBytes=" + totalSizeInBytes
                      + ", count=" + count
                      + ", maxSizeInBytes=" + maxSizeInBytes
                      + '}';
          }
      }
  }
  