android-16.0.0_r2/s

/*
 * Copyright (C) 2023 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.power.stats;

import android.annotation.NonNull;
import android.annotation.Nullable;
import android.os.BatteryUsageStats;
import android.os.FileUtils;
import android.os.Handler;
import android.util.AtomicFile;
import android.util.IndentingPrintWriter;
import android.util.Slog;
import android.util.Xml;

import com.android.internal.annotations.VisibleForTesting;
import com.android.modules.utils.TypedXmlPullParser;

import org.xmlpull.v1.XmlPullParserException;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.channels.Channel;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.nio.charset.StandardCharsets;
import java.nio.file.StandardOpenOption;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.locks.ReentrantLock;

/**
 * A storage mechanism for aggregated power/battery stats.
 */
public class PowerStatsStore {
    private static final String TAG = "PowerStatsStore";

    private static final String POWER_STATS_DIR = "power-stats";
    private static final String POWER_STATS_SPAN_FILE_EXTENSION = ".pss";
    private static final String DIR_LOCK_FILENAME = ".lock";
    private static final long MAX_POWER_STATS_SPAN_STORAGE_BYTES = 100 * 1024;

    private final File mSystemDir;
    private final File mStoreDir;
    private final File mLockFile;
    private final ReentrantLock mFileLock = new ReentrantLock();
    private FileLock mJvmLock;
    private final long mMaxStorageBytes;
    private final Handler mHandler;
    private final Map<String, PowerStatsSpan.SectionReader> mSectionReaders = new HashMap<>();
    private volatile List<PowerStatsSpan.Metadata> mTableOfContents;

    public PowerStatsStore(@NonNull File systemDir, Handler handler) {
        this(systemDir, MAX_POWER_STATS_SPAN_STORAGE_BYTES, handler);
    }

    @VisibleForTesting
    public PowerStatsStore(@NonNull File systemDir, long maxStorageBytes, Handler handler) {
        mSystemDir = systemDir;
        mStoreDir = new File(systemDir, POWER_STATS_DIR);
        mLockFile = new File(mStoreDir, DIR_LOCK_FILENAME);
        mHandler = handler;
        mMaxStorageBytes = maxStorageBytes;
        mHandler.post(this::maybeClearLegacyStore);
    }

    /**
     * Registers a Reader for a section type, which is determined by `sectionReader.getType()`
     */
    public void addSectionReader(PowerStatsSpan.SectionReader sectionReader) {
        mSectionReaders.put(sectionReader.getType(), sectionReader);
    }

    /**
     * Returns the metadata for all {@link PowerStatsSpan}'s contained in the store.
     */
    @NonNull
    public List<PowerStatsSpan.Metadata> getTableOfContents() {
        List<PowerStatsSpan.Metadata> toc = mTableOfContents;
        if (toc != null) {
            return toc;
        }

        TypedXmlPullParser parser = Xml.newBinaryPullParser();
        lockStoreDirectory();
        try {
            toc = new ArrayList<>();
            for (File file : mStoreDir.listFiles()) {
                String fileName = file.getName();
                if (!fileName.endsWith(POWER_STATS_SPAN_FILE_EXTENSION)) {
                    continue;
                }
                try (InputStream inputStream = new BufferedInputStream(new FileInputStream(file))) {
                    parser.setInput(inputStream, StandardCharsets.UTF_8.name());
                    PowerStatsSpan.Metadata metadata = PowerStatsSpan.Metadata.read(parser);
                    if (metadata != null) {
                        toc.add(metadata);
                    } else {
                        Slog.e(TAG, "Removing incompatible PowerStatsSpan file: " + fileName);
                        file.delete();
                    }
                } catch (IOException | XmlPullParserException e) {
                    Slog.wtf(TAG, "Cannot read PowerStatsSpan file: " + fileName);
                }
            }
            toc.sort(PowerStatsSpan.Metadata.COMPARATOR);
            mTableOfContents = Collections.unmodifiableList(toc);
        } finally {
            unlockStoreDirectory();
        }

        return toc;
    }

    /**
     * Schedules saving the specified span on the background thread.
     */
    public void storePowerStatsSpanAsync(PowerStatsSpan span, Runnable onComplete) {
        mHandler.post(() -> {
            try {
                storePowerStatsSpan(span);
            } finally {
                onComplete.run();
            }
        });
    }

    /**
     * Saves the specified span in the store.
     */
    public void storePowerStatsSpan(PowerStatsSpan span) {
        lockStoreDirectory();
        try {
            if (!mStoreDir.exists()) {
                if (!mStoreDir.mkdirs()) {
                    Slog.e(TAG, "Could not create a directory for power stats store");
                    return;
                }
            }

            AtomicFile file = new AtomicFile(makePowerStatsSpanFilename(span.getId()));
            file.write(out-> {
                try {
                    span.writeXml(out, Xml.newBinarySerializer());
                } catch (Exception e) {
                    // AtomicFile will log the exception and delete the file.
                    throw new RuntimeException(e);
                }
            });
            mTableOfContents = null;
            removeOldSpansLocked();
        } finally {
            unlockStoreDirectory();
        }
    }

    /**
     * Loads the PowerStatsSpan identified by its ID. Only loads the sections with
     * the specified types.  Loads all sections if no sectionTypes is empty.
     */
    @Nullable
    public PowerStatsSpan loadPowerStatsSpan(long id, String... sectionTypes) {
        TypedXmlPullParser parser = Xml.newBinaryPullParser();
        lockStoreDirectory();
        try {
            File file = makePowerStatsSpanFilename(id);
            if (!file.exists()) {
                return null;
            }
            try (InputStream inputStream = new BufferedInputStream(new FileInputStream(file))) {
                return PowerStatsSpan.read(inputStream, parser, mSectionReaders, sectionTypes);
            } catch (IOException | XmlPullParserException e) {
                Slog.wtf(TAG, "Cannot read PowerStatsSpan file: " + file, e);
            }
        } finally {
            unlockStoreDirectory();
        }
        return null;
    }

    /**
     * Stores a {@link PowerStatsSpan} containing a single section for the supplied
     * battery usage stats.
     */
    public void storeBatteryUsageStatsAsync(long monotonicStartTime,
            BatteryUsageStats batteryUsageStats) {
        if (mHandler.getLooper().isCurrentThread()) {
            storeBatteryUsageStats(monotonicStartTime, batteryUsageStats);
        } else {
            mHandler.post(() -> {
                storeBatteryUsageStats(monotonicStartTime, batteryUsageStats);
            });
        }
    }

    private void storeBatteryUsageStats(long monotonicStartTime,
            BatteryUsageStats batteryUsageStats) {
        try {
            PowerStatsSpan span = new PowerStatsSpan(monotonicStartTime);
            span.addTimeFrame(monotonicStartTime, batteryUsageStats.getStatsStartTimestamp(),
                    batteryUsageStats.getStatsDuration());
            span.addSection(new BatteryUsageStatsSection(batteryUsageStats));
            storePowerStatsSpan(span);
        } finally {
            try {
                batteryUsageStats.close();
            } catch (IOException e) {
                Slog.e(TAG, "Cannot close BatteryUsageStats", e);
            }
        }
    }

    /**
     * Creates a file name by formatting the span ID as a 19-digit zero-padded number.
     * This ensures that the lexicographically sorted directory follows the chronological order.
     */
    private File makePowerStatsSpanFilename(long id) {
        return new File(mStoreDir, String.format(Locale.ENGLISH, "%019d", id)
                                   + POWER_STATS_SPAN_FILE_EXTENSION);
    }

    private void maybeClearLegacyStore() {
        File legacyStoreDir = new File(mSystemDir, "battery-usage-stats");
        if (legacyStoreDir.exists()) {
            FileUtils.deleteContentsAndDir(legacyStoreDir);
        }
    }

    private void lockStoreDirectory() {
        mFileLock.lock();

        // Lock the directory from access by other JVMs
        try {
            if (!mLockFile.exists()) {
                mLockFile.getParentFile().mkdirs();
                mLockFile.createNewFile();
            }
            mJvmLock = FileChannel.open(mLockFile.toPath(), StandardOpenOption.WRITE).lock();
        } catch (IOException e) {
            Slog.e(TAG, "Cannot lock snapshot directory", e);
        }
    }

    private void unlockStoreDirectory() {
        try {
            Channel channel = mJvmLock.acquiredBy();
            mJvmLock.release();
            channel.close();
        } catch (IOException e) {
            Slog.e(TAG, "Cannot unlock snapshot directory", e);
        } finally {
            mJvmLock = null;
            mFileLock.unlock();
        }
    }

    private void removeOldSpansLocked() {
        // Read the directory list into a _sorted_ map.  The alphanumeric ordering
        // corresponds to the historical order of snapshots because the file names
        // are timestamps zero-padded to the same length.
        long totalSize = 0;
        TreeMap<File, Long> mFileSizes = new TreeMap<>();
        for (File file : mStoreDir.listFiles()) {
            final long fileSize = file.length();
            totalSize += fileSize;
            if (file.getName().endsWith(POWER_STATS_SPAN_FILE_EXTENSION)) {
                mFileSizes.put(file, fileSize);
            }
        }

        while (totalSize > mMaxStorageBytes) {
            final Map.Entry<File, Long> entry = mFileSizes.firstEntry();
            if (entry == null) {
                break;
            }

            File file = entry.getKey();
            if (!file.delete()) {
                Slog.e(TAG, "Cannot delete power stats span " + file);
            }
            totalSize -= entry.getValue();
            mFileSizes.remove(file);
            mTableOfContents = null;
        }
    }

    /**
     * Deletes all contents from the store.
     */
    public void reset() {
        lockStoreDirectory();
        try {
            for (File file : mStoreDir.listFiles()) {
                if (file.getName().endsWith(POWER_STATS_SPAN_FILE_EXTENSION)) {
                    if (!file.delete()) {
                        Slog.e(TAG, "Cannot delete power stats span " + file);
                    }
                }
            }
            mTableOfContents = List.of();
        } finally {
            unlockStoreDirectory();
        }
    }

    /**
     * Prints the summary of contents of the store: only metadata, but not the actual stored
     * objects.
     */
    public void dumpTableOfContents(IndentingPrintWriter ipw) {
        ipw.println("Power stats store TOC");
        ipw.increaseIndent();
        List<PowerStatsSpan.Metadata> contents = getTableOfContents();
        for (PowerStatsSpan.Metadata metadata : contents) {
            metadata.dump(ipw);
        }
        ipw.decreaseIndent();
    }

    /**
     * Prints the contents of the store.
     */
    public void dump(IndentingPrintWriter ipw) {
        ipw.println("Power stats store");
        ipw.increaseIndent();
        List<PowerStatsSpan.Metadata> contents = getTableOfContents();
        for (PowerStatsSpan.Metadata metadata : contents) {
            try (PowerStatsSpan span = loadPowerStatsSpan(metadata.getId())) {
                if (span != null) {
                    span.dump(ipw);
                }
            }
        }
        ipw.decreaseIndent();
    }
}