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Android example source code file (DeviceStorageMonitorService.java)

This example Android source code file (DeviceStorageMonitorService.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

android, app, cachepackagedataobserver, content, debug, default_disk_free_change_reporting_threshold, default_free_storage_log_interval_in_minutes, device_memory_what, devicestoragemonitorservice, illegalargumentexception, intent, notification, notificationmanager, os, running, sending, statfs, string, util, utilities

The DeviceStorageMonitorService.java Android example source code

 * Copyright (C) 2007-2008 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,
 * See the License for the specific language governing permissions and
 * limitations under the License.

package com.android.server;

import com.android.server.am.ActivityManagerService;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.pm.IPackageDataObserver;
import android.content.pm.IPackageManager;
import android.os.Binder;
import android.os.Handler;
import android.os.Message;
import android.os.Process;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.os.StatFs;
import android.os.SystemClock;
import android.os.SystemProperties;
import android.provider.Settings;
import android.util.Config;
import android.util.EventLog;
import android.util.Slog;
import android.provider.Settings;

 * This class implements a service to monitor the amount of disk
 * storage space on the device.  If the free storage on device is less
 * than a tunable threshold value (a secure settings parameter;
 * default 10%) a low memory notification is displayed to alert the
 * user. If the user clicks on the low memory notification the
 * Application Manager application gets launched to let the user free
 * storage space.
 * Event log events: A low memory event with the free storage on
 * device in bytes is logged to the event log when the device goes low
 * on storage space.  The amount of free storage on the device is
 * periodically logged to the event log. The log interval is a secure
 * settings parameter with a default value of 12 hours.  When the free
 * storage differential goes below a threshold (again a secure
 * settings parameter with a default value of 2MB), the free memory is
 * logged to the event log.
class DeviceStorageMonitorService extends Binder {
    private static final String TAG = "DeviceStorageMonitorService";
    private static final boolean DEBUG = false;
    private static final boolean localLOGV = DEBUG ? Config.LOGD : Config.LOGV;
    private static final int DEVICE_MEMORY_WHAT = 1;
    private static final int MONITOR_INTERVAL = 1; //in minutes
    private static final int LOW_MEMORY_NOTIFICATION_ID = 1;
    private static final int DEFAULT_THRESHOLD_PERCENTAGE = 10;
    private static final int DEFAULT_FREE_STORAGE_LOG_INTERVAL_IN_MINUTES = 12*60; //in minutes
    private static final long DEFAULT_DISK_FREE_CHANGE_REPORTING_THRESHOLD = 2 * 1024 * 1024; // 2MB
    private static final long DEFAULT_CHECK_INTERVAL = MONITOR_INTERVAL*60*1000;
    private long mFreeMem;  // on /data
    private long mLastReportedFreeMem;
    private long mLastReportedFreeMemTime;
    private boolean mLowMemFlag=false;
    private Context mContext;
    private ContentResolver mContentResolver;
    private long mTotalMemory;  // on /data
    private StatFs mDataFileStats;
    private StatFs mSystemFileStats;
    private StatFs mCacheFileStats;
    private static final String DATA_PATH = "/data";
    private static final String SYSTEM_PATH = "/system";
    private static final String CACHE_PATH = "/cache";
    private long mThreadStartTime = -1;
    private boolean mClearSucceeded = false;
    private boolean mClearingCache;
    private Intent mStorageLowIntent;
    private Intent mStorageOkIntent;
    private CachePackageDataObserver mClearCacheObserver;
    private static final int _TRUE = 1;
    private static final int _FALSE = 0;

     * This string is used for ServiceManager access to this class.
    static final String SERVICE = "devicestoragemonitor";

    * Handler that checks the amount of disk space on the device and sends a
    * notification if the device runs low on disk space
    Handler mHandler = new Handler() {
        public void handleMessage(Message msg) {
            //dont handle an invalid message
            if (msg.what != DEVICE_MEMORY_WHAT) {
                Slog.e(TAG, "Will not process invalid message");
            checkMemory(msg.arg1 == _TRUE);

    class CachePackageDataObserver extends IPackageDataObserver.Stub {
        public void onRemoveCompleted(String packageName, boolean succeeded) {
            mClearSucceeded = succeeded;
            mClearingCache = false;
            if(localLOGV) Slog.i(TAG, " Clear succeeded:"+mClearSucceeded
                    +", mClearingCache:"+mClearingCache+" Forcing memory check");
            postCheckMemoryMsg(false, 0);

    private final void restatDataDir() {
        try {
            mFreeMem = (long) mDataFileStats.getAvailableBlocks() *
        } catch (IllegalArgumentException e) {
            // use the old value of mFreeMem
        // Allow freemem to be overridden by debug.freemem for testing
        String debugFreeMem = SystemProperties.get("debug.freemem");
        if (!"".equals(debugFreeMem)) {
            mFreeMem = Long.parseLong(debugFreeMem);
        // Read the log interval from secure settings
        long freeMemLogInterval = Settings.Secure.getLong(mContentResolver,
        //log the amount of free memory in event log
        long currTime = SystemClock.elapsedRealtime();
        if((mLastReportedFreeMemTime == 0) ||
           (currTime-mLastReportedFreeMemTime) >= freeMemLogInterval) {
            mLastReportedFreeMemTime = currTime;
            long mFreeSystem = -1, mFreeCache = -1;
            try {
                mFreeSystem = (long) mSystemFileStats.getAvailableBlocks() *
            } catch (IllegalArgumentException e) {
                // ignore; report -1
            try {
                mFreeCache = (long) mCacheFileStats.getAvailableBlocks() *
            } catch (IllegalArgumentException e) {
                // ignore; report -1
                                mFreeMem, mFreeSystem, mFreeCache);
        // Read the reporting threshold from secure settings
        long threshold = Settings.Secure.getLong(mContentResolver,
        // If mFree changed significantly log the new value
        long delta = mFreeMem - mLastReportedFreeMem;
        if (delta > threshold || delta < -threshold) {
            mLastReportedFreeMem = mFreeMem;
            EventLog.writeEvent(EventLogTags.FREE_STORAGE_CHANGED, mFreeMem);

    private final void clearCache() {
        if (mClearCacheObserver == null) {
            // Lazy instantiation
            mClearCacheObserver = new CachePackageDataObserver();
        mClearingCache = true;
        try {
            if (localLOGV) Slog.i(TAG, "Clearing cache");
                    freeStorageAndNotify(getMemThreshold(), mClearCacheObserver);
        } catch (RemoteException e) {
            Slog.w(TAG, "Failed to get handle for PackageManger Exception: "+e);
            mClearingCache = false;
            mClearSucceeded = false;

    private final void checkMemory(boolean checkCache) {
        //if the thread that was started to clear cache is still running do nothing till its
        //finished clearing cache. Ideally this flag could be modified by clearCache
        // and should be accessed via a lock but even if it does this test will fail now and
        //hopefully the next time this flag will be set to the correct value.
        if(mClearingCache) {
            if(localLOGV) Slog.i(TAG, "Thread already running just skip");
            //make sure the thread is not hung for too long
            long diffTime = System.currentTimeMillis() - mThreadStartTime;
            if(diffTime > (10*60*1000)) {
                Slog.w(TAG, "Thread that clears cache file seems to run for ever");
        } else {
            if (localLOGV)  Slog.v(TAG, "freeMemory="+mFreeMem);

            //post intent to NotificationManager to display icon if necessary
            long memThreshold = getMemThreshold();
            if (mFreeMem < memThreshold) {
                if (!mLowMemFlag) {
                    if (checkCache) {
                        // See if clearing cache helps
                        // Note that clearing cache is asynchronous and so we do a
                        // memory check again once the cache has been cleared.
                        mThreadStartTime = System.currentTimeMillis();
                        mClearSucceeded = false;
                    } else {
                        Slog.i(TAG, "Running low on memory. Sending notification");
                        mLowMemFlag = true;
                } else {
                    if (localLOGV) Slog.v(TAG, "Running low on memory " +
                            "notification already sent. do nothing");
            } else {
                if (mLowMemFlag) {
                    Slog.i(TAG, "Memory available. Cancelling notification");
                    mLowMemFlag = false;
        if(localLOGV) Slog.i(TAG, "Posting Message again");
        //keep posting messages to itself periodically
        postCheckMemoryMsg(true, DEFAULT_CHECK_INTERVAL);

    private void postCheckMemoryMsg(boolean clearCache, long delay) {
        // Remove queued messages
                clearCache ?_TRUE : _FALSE, 0),

     * just query settings to retrieve the memory threshold.
     * Preferred this over using a ContentObserver since Settings.Secure caches the value
     * any way
    private long getMemThreshold() {
        int value = Settings.Secure.getInt(
        if(localLOGV) Slog.v(TAG, "Threshold Percentage="+value);
        //evaluate threshold value
        return mTotalMemory*value;

    * Constructor to run service. initializes the disk space threshold value
    * and posts an empty message to kickstart the process.
    public DeviceStorageMonitorService(Context context) {
        mLastReportedFreeMemTime = 0;
        mContext = context;
        mContentResolver = mContext.getContentResolver();
        //create StatFs object
        mDataFileStats = new StatFs(DATA_PATH);
        mSystemFileStats = new StatFs(SYSTEM_PATH);
        mCacheFileStats = new StatFs(CACHE_PATH);
        //initialize total storage on device
        mTotalMemory = ((long)mDataFileStats.getBlockCount() *
        mStorageLowIntent = new Intent(Intent.ACTION_DEVICE_STORAGE_LOW);
        mStorageOkIntent = new Intent(Intent.ACTION_DEVICE_STORAGE_OK);

    * This method sends a notification to NotificationManager to display
    * an error dialog indicating low disk space and launch the Installer
    * application
    private final void sendNotification() {
        if(localLOGV) Slog.i(TAG, "Sending low memory notification");
        //log the event to event log with the amount of free storage(in bytes) left on the device
        EventLog.writeEvent(EventLogTags.LOW_STORAGE, mFreeMem);
        //  Pack up the values and broadcast them to everyone
        Intent lowMemIntent = new Intent(Intent.ACTION_MANAGE_PACKAGE_STORAGE);
        lowMemIntent.putExtra("memory", mFreeMem);
        NotificationManager mNotificationMgr =
        CharSequence title = mContext.getText(
        CharSequence details = mContext.getText(
        PendingIntent intent = PendingIntent.getActivity(mContext, 0,  lowMemIntent, 0);
        Notification notification = new Notification();
        notification.icon = com.android.internal.R.drawable.stat_notify_disk_full;
        notification.tickerText = title;
        notification.flags |= Notification.FLAG_NO_CLEAR;
        notification.setLatestEventInfo(mContext, title, details, intent);
        mNotificationMgr.notify(LOW_MEMORY_NOTIFICATION_ID, notification);

     * Cancels low storage notification and sends OK intent.
    private final void cancelNotification() {
        if(localLOGV) Slog.i(TAG, "Canceling low memory notification");
        NotificationManager mNotificationMgr =
        //cancel notification since memory has been freed


    public void updateMemory() {
        int callingUid = getCallingUid();
        if(callingUid != Process.SYSTEM_UID) {
        // force an early check
        postCheckMemoryMsg(true, 0);

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