Increment operation counts to track downloads.
[android/platform/packages/providers/DownloadProvider.git] / src / com / android / providers / downloads / DownloadThread.java
index eb59d3f..28bbf49 100644 (file)
 
 package com.android.providers.downloads;
 
-import static android.text.format.DateUtils.MINUTE_IN_MILLIS;
+import static android.provider.Downloads.Impl.STATUS_BAD_REQUEST;
+import static android.provider.Downloads.Impl.STATUS_CANNOT_RESUME;
+import static android.provider.Downloads.Impl.STATUS_FILE_ERROR;
+import static android.provider.Downloads.Impl.STATUS_HTTP_DATA_ERROR;
+import static android.provider.Downloads.Impl.STATUS_SUCCESS;
+import static android.provider.Downloads.Impl.STATUS_TOO_MANY_REDIRECTS;
+import static android.provider.Downloads.Impl.STATUS_WAITING_FOR_NETWORK;
+import static android.provider.Downloads.Impl.STATUS_WAITING_TO_RETRY;
+import static android.text.format.DateUtils.SECOND_IN_MILLIS;
 import static com.android.providers.downloads.Constants.TAG;
+import static java.net.HttpURLConnection.HTTP_INTERNAL_ERROR;
+import static java.net.HttpURLConnection.HTTP_MOVED_PERM;
+import static java.net.HttpURLConnection.HTTP_MOVED_TEMP;
 import static java.net.HttpURLConnection.HTTP_OK;
 import static java.net.HttpURLConnection.HTTP_PARTIAL;
+import static java.net.HttpURLConnection.HTTP_SEE_OTHER;
 import static java.net.HttpURLConnection.HTTP_UNAVAILABLE;
 
 import android.content.ContentValues;
@@ -27,7 +39,9 @@ import android.content.Context;
 import android.content.Intent;
 import android.drm.DrmManagerClient;
 import android.drm.DrmOutputStream;
+import android.net.ConnectivityManager;
 import android.net.INetworkPolicyListener;
+import android.net.NetworkInfo;
 import android.net.NetworkPolicyManager;
 import android.net.TrafficStats;
 import android.os.FileUtils;
@@ -39,6 +53,10 @@ import android.text.TextUtils;
 import android.util.Log;
 import android.util.Pair;
 
+import com.android.providers.downloads.DownloadInfo.NetworkState;
+
+import libcore.io.IoUtils;
+
 import java.io.File;
 import java.io.FileDescriptor;
 import java.io.FileOutputStream;
@@ -47,34 +65,39 @@ import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.RandomAccessFile;
 import java.net.HttpURLConnection;
+import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLConnection;
 
-import libcore.io.IoUtils;
-
 /**
- * Thread which executes a given {@link DownloadInfo}: making network requests,
+ * Task which executes a given {@link DownloadInfo}: making network requests,
  * persisting data to disk, and updating {@link DownloadProvider}.
  */
-public class DownloadThread extends Thread {
+public class DownloadThread implements Runnable {
+
+    // TODO: bind each download to a specific network interface to avoid state
+    // checking races once we have ConnectivityManager API
 
     private static final int HTTP_REQUESTED_RANGE_NOT_SATISFIABLE = 416;
+    private static final int HTTP_TEMP_REDIRECT = 307;
 
-    private static final int DEFAULT_TIMEOUT = (int) MINUTE_IN_MILLIS;
+    private static final int DEFAULT_TIMEOUT = (int) (20 * SECOND_IN_MILLIS);
 
     private final Context mContext;
     private final DownloadInfo mInfo;
     private final SystemFacade mSystemFacade;
     private final StorageManager mStorageManager;
+    private final DownloadNotifier mNotifier;
 
     private volatile boolean mPolicyDirty;
 
     public DownloadThread(Context context, SystemFacade systemFacade, DownloadInfo info,
-            StorageManager storageManager) {
+            StorageManager storageManager, DownloadNotifier notifier) {
         mContext = context;
         mSystemFacade = systemFacade;
         mInfo = info;
         mStorageManager = storageManager;
+        mNotifier = notifier;
     }
 
     /**
@@ -94,7 +117,6 @@ public class DownloadThread extends Thread {
     static class State {
         public String mFilename;
         public String mMimeType;
-        public boolean mCountRetry = false;
         public int mRetryAfter = 0;
         public boolean mGotData = false;
         public String mRequestUri;
@@ -104,6 +126,7 @@ public class DownloadThread extends Thread {
         public boolean mContinuingDownload = false;
         public long mBytesNotified = 0;
         public long mTimeLastNotification = 0;
+        public int mNetworkType = ConnectivityManager.TYPE_NONE;
 
         /** Historical bytes/second speed of this download. */
         public long mSpeed;
@@ -116,6 +139,9 @@ public class DownloadThread extends Thread {
         public String mContentDisposition;
         public String mContentLocation;
 
+        public int mRedirectionCount;
+        public URL mUrl;
+
         public State(DownloadInfo info) {
             mMimeType = Intent.normalizeMimeType(info.mMimeType);
             mRequestUri = info.mUri;
@@ -129,19 +155,17 @@ public class DownloadThread extends Thread {
             mContentLength = -1;
             mContentDisposition = null;
             mContentLocation = null;
+            mRedirectionCount = 0;
         }
     }
 
-    /**
-     * Executes the download in a separate thread
-     */
     @Override
     public void run() {
         Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
         try {
             runInternal();
         } finally {
-            DownloadHandler.getInstance().dequeueDownload(mInfo.mId);
+            mNotifier.notifyDownloadSpeed(mInfo.mId, 0);
         }
     }
 
@@ -157,6 +181,7 @@ public class DownloadThread extends Thread {
         State state = new State(mInfo);
         PowerManager.WakeLock wakeLock = null;
         int finalStatus = Downloads.Impl.STATUS_UNKNOWN_ERROR;
+        int numFailed = mInfo.mNumFailed;
         String errorMsg = null;
 
         final NetworkPolicyManager netPolicy = NetworkPolicyManager.from(mContext);
@@ -169,34 +194,29 @@ public class DownloadThread extends Thread {
             // while performing download, register for rules updates
             netPolicy.registerListener(mPolicyListener);
 
-            if (Constants.LOGV) {
-                Log.v(Constants.TAG, "initiating download for " + mInfo.mUri);
+            Log.i(Constants.TAG, "Download " + mInfo.mId + " starting");
+
+            // Remember which network this download started on; used to
+            // determine if errors were due to network changes.
+            final NetworkInfo info = mSystemFacade.getActiveNetworkInfo(mInfo.mUid);
+            if (info != null) {
+                state.mNetworkType = info.getType();
             }
 
-            // network traffic on this thread should be counted against the
-            // requesting uid, and is tagged with well-known value.
+            // Network traffic on this thread should be counted against the
+            // requesting UID, and is tagged with well-known value.
             TrafficStats.setThreadStatsTag(TrafficStats.TAG_SYSTEM_DOWNLOAD);
             TrafficStats.setThreadStatsUid(mInfo.mUid);
 
-            boolean finished = false;
-            while (!finished) {
-                Log.i(Constants.TAG, "Initiating request for download " + mInfo.mId);
-
-                final URL url = new URL(state.mRequestUri);
-                final HttpURLConnection conn = (HttpURLConnection) url.openConnection();
-                conn.setConnectTimeout(DEFAULT_TIMEOUT);
-                conn.setReadTimeout(DEFAULT_TIMEOUT);
-                try {
-                    executeDownload(state, conn);
-                    finished = true;
-                } finally {
-                    conn.disconnect();
-                }
+            try {
+                // TODO: migrate URL sanity checking into client side of API
+                state.mUrl = new URL(state.mRequestUri);
+            } catch (MalformedURLException e) {
+                throw new StopRequestException(STATUS_BAD_REQUEST, e);
             }
 
-            if (Constants.LOGV) {
-                Log.v(Constants.TAG, "download completed for " + mInfo.mUri);
-            }
+            executeDownload(state);
+
             finalizeDestinationFile(state);
             finalStatus = Downloads.Impl.STATUS_SUCCESS;
         } catch (StopRequestException error) {
@@ -207,7 +227,35 @@ public class DownloadThread extends Thread {
             if (Constants.LOGV) {
                 Log.w(Constants.TAG, msg, error);
             }
-            finalStatus = error.mFinalStatus;
+            finalStatus = error.getFinalStatus();
+
+            // Nobody below our level should request retries, since we handle
+            // failure counts at this level.
+            if (finalStatus == STATUS_WAITING_TO_RETRY) {
+                throw new IllegalStateException("Execution should always throw final error codes");
+            }
+
+            // Some errors should be retryable, unless we fail too many times.
+            if (isStatusRetryable(finalStatus)) {
+                if (state.mGotData) {
+                    numFailed = 1;
+                } else {
+                    numFailed += 1;
+                }
+
+                if (numFailed < Constants.MAX_RETRIES) {
+                    final NetworkInfo info = mSystemFacade.getActiveNetworkInfo(mInfo.mUid);
+                    if (info != null && info.getType() == state.mNetworkType
+                            && info.isConnected()) {
+                        // Underlying network is still intact, use normal backoff
+                        finalStatus = STATUS_WAITING_TO_RETRY;
+                    } else {
+                        // Network changed, retry on any next available
+                        finalStatus = STATUS_WAITING_FOR_NETWORK;
+                    }
+                }
+            }
+
             // fall through to finally block
         } catch (Throwable ex) {
             errorMsg = ex.getMessage();
@@ -216,12 +264,18 @@ public class DownloadThread extends Thread {
             finalStatus = Downloads.Impl.STATUS_UNKNOWN_ERROR;
             // falls through to the code that reports an error
         } finally {
+            if (finalStatus == STATUS_SUCCESS) {
+                TrafficStats.incrementOperationCount(1);
+            }
+
             TrafficStats.clearThreadStatsTag();
             TrafficStats.clearThreadStatsUid();
 
             cleanupDestination(state, finalStatus);
-            notifyDownloadCompleted(finalStatus, state.mCountRetry, state.mRetryAfter,
-                    state.mGotData, state.mFilename, state.mMimeType, errorMsg);
+            notifyDownloadCompleted(state, finalStatus, errorMsg, numFailed);
+
+            Log.i(Constants.TAG, "Download " + mInfo.mId + " finished with status "
+                    + Downloads.Impl.statusToString(finalStatus));
 
             netPolicy.unregisterListener(mPolicyListener);
 
@@ -234,14 +288,12 @@ public class DownloadThread extends Thread {
     }
 
     /**
-     * Fully execute a single download request - setup and send the request, handle the response,
-     * and transfer the data to the destination file.
+     * Fully execute a single download request. Setup and send the request,
+     * handle the response, and transfer the data to the destination file.
      */
-    private void executeDownload(State state, HttpURLConnection conn) throws StopRequestException {
+    private void executeDownload(State state) throws StopRequestException {
         state.resetBeforeExecute();
-
         setupDestinationFile(state);
-        addRequestHeaders(state, conn);
 
         // skip when already finished; remove after fixing race in 5217390
         if (state.mCurrentBytes == state.mTotalBytes) {
@@ -250,24 +302,92 @@ public class DownloadThread extends Thread {
             return;
         }
 
-        // check just before sending the request to avoid using an invalid connection at all
-        checkConnectivity();
+        while (state.mRedirectionCount++ < Constants.MAX_REDIRECTS) {
+            // Open connection and follow any redirects until we have a useful
+            // response with body.
+            HttpURLConnection conn = null;
+            try {
+                checkConnectivity();
+                conn = (HttpURLConnection) state.mUrl.openConnection();
+                conn.setInstanceFollowRedirects(false);
+                conn.setConnectTimeout(DEFAULT_TIMEOUT);
+                conn.setReadTimeout(DEFAULT_TIMEOUT);
 
+                addRequestHeaders(state, conn);
+
+                final int responseCode = conn.getResponseCode();
+                switch (responseCode) {
+                    case HTTP_OK:
+                        if (state.mContinuingDownload) {
+                            throw new StopRequestException(
+                                    STATUS_CANNOT_RESUME, "Expected partial, but received OK");
+                        }
+                        processResponseHeaders(state, conn);
+                        transferData(state, conn);
+                        return;
+
+                    case HTTP_PARTIAL:
+                        if (!state.mContinuingDownload) {
+                            throw new StopRequestException(
+                                    STATUS_CANNOT_RESUME, "Expected OK, but received partial");
+                        }
+                        transferData(state, conn);
+                        return;
+
+                    case HTTP_MOVED_PERM:
+                    case HTTP_MOVED_TEMP:
+                    case HTTP_SEE_OTHER:
+                    case HTTP_TEMP_REDIRECT:
+                        final String location = conn.getHeaderField("Location");
+                        state.mUrl = new URL(state.mUrl, location);
+                        if (responseCode == HTTP_MOVED_PERM) {
+                            // Push updated URL back to database
+                            state.mRequestUri = state.mUrl.toString();
+                        }
+                        continue;
+
+                    case HTTP_REQUESTED_RANGE_NOT_SATISFIABLE:
+                        throw new StopRequestException(
+                                STATUS_CANNOT_RESUME, "Requested range not satisfiable");
+
+                    case HTTP_UNAVAILABLE:
+                        parseRetryAfterHeaders(state, conn);
+                        throw new StopRequestException(
+                                HTTP_UNAVAILABLE, conn.getResponseMessage());
+
+                    case HTTP_INTERNAL_ERROR:
+                        throw new StopRequestException(
+                                HTTP_INTERNAL_ERROR, conn.getResponseMessage());
+
+                    default:
+                        StopRequestException.throwUnhandledHttpError(
+                                responseCode, conn.getResponseMessage());
+                }
+            } catch (IOException e) {
+                // Trouble with low-level sockets
+                throw new StopRequestException(STATUS_HTTP_DATA_ERROR, e);
+
+            } finally {
+                if (conn != null) conn.disconnect();
+            }
+        }
+
+        throw new StopRequestException(STATUS_TOO_MANY_REDIRECTS, "Too many redirects");
+    }
+
+    /**
+     * Transfer data from the given connection to the destination file.
+     */
+    private void transferData(State state, HttpURLConnection conn) throws StopRequestException {
         DrmManagerClient drmClient = null;
         InputStream in = null;
         OutputStream out = null;
         FileDescriptor outFd = null;
         try {
             try {
-                // Asking for response code will execute the request
-                final int statusCode = conn.getResponseCode();
                 in = conn.getInputStream();
-
-                handleExceptionalStatus(state, conn, statusCode);
-                processResponseHeaders(state, conn);
             } catch (IOException e) {
-                throw new StopRequestException(
-                        getFinalStatusForHttpError(state), "Request failed: " + e, e);
+                throw new StopRequestException(STATUS_HTTP_DATA_ERROR, e);
             }
 
             try {
@@ -282,10 +402,11 @@ public class DownloadThread extends Thread {
                     outFd = ((FileOutputStream) out).getFD();
                 }
             } catch (IOException e) {
-                throw new StopRequestException(
-                        Downloads.Impl.STATUS_FILE_ERROR, "Failed to open destination: " + e, e);
+                throw new StopRequestException(STATUS_FILE_ERROR, e);
             }
 
+            // Start streaming data, periodically watch for pause/cancel
+            // commands and checking disk space as needed.
             transferData(state, in, out);
 
             try {
@@ -293,8 +414,7 @@ public class DownloadThread extends Thread {
                     ((DrmOutputStream) out).finish();
                 }
             } catch (IOException e) {
-                throw new StopRequestException(
-                        Downloads.Impl.STATUS_FILE_ERROR, "Failed to finish: " + e, e);
+                throw new StopRequestException(STATUS_FILE_ERROR, e);
             }
 
         } finally {
@@ -321,18 +441,17 @@ public class DownloadThread extends Thread {
         // checking connectivity will apply current policy
         mPolicyDirty = false;
 
-        int networkUsable = mInfo.checkCanUseNetwork();
-        if (networkUsable != DownloadInfo.NETWORK_OK) {
+        final NetworkState networkUsable = mInfo.checkCanUseNetwork();
+        if (networkUsable != NetworkState.OK) {
             int status = Downloads.Impl.STATUS_WAITING_FOR_NETWORK;
-            if (networkUsable == DownloadInfo.NETWORK_UNUSABLE_DUE_TO_SIZE) {
+            if (networkUsable == NetworkState.UNUSABLE_DUE_TO_SIZE) {
                 status = Downloads.Impl.STATUS_QUEUED_FOR_WIFI;
                 mInfo.notifyPauseDueToSize(true);
-            } else if (networkUsable == DownloadInfo.NETWORK_RECOMMENDED_UNUSABLE_DUE_TO_SIZE) {
+            } else if (networkUsable == NetworkState.RECOMMENDED_UNUSABLE_DUE_TO_SIZE) {
                 status = Downloads.Impl.STATUS_QUEUED_FOR_WIFI;
                 mInfo.notifyPauseDueToSize(false);
             }
-            throw new StopRequestException(status,
-                    mInfo.getLogMessageForNetworkError(networkUsable));
+            throw new StopRequestException(status, networkUsable.name());
         }
     }
 
@@ -426,10 +545,13 @@ public class DownloadThread extends Thread {
                 state.mSpeed = ((state.mSpeed * 3) + sampleSpeed) / 4;
             }
 
+            // Only notify once we have a full sample window
+            if (state.mSpeedSampleStart != 0) {
+                mNotifier.notifyDownloadSpeed(mInfo.mId, state.mSpeed);
+            }
+
             state.mSpeedSampleStart = now;
             state.mSpeedSampleBytes = state.mCurrentBytes;
-
-            DownloadHandler.getInstance().setCurrentSpeed(mInfo.mId, state.mSpeed);
         }
 
         if (state.mCurrentBytes - state.mBytesNotified > Constants.MIN_PROGRESS_STEP &&
@@ -487,10 +609,10 @@ public class DownloadThread extends Thread {
                 && (state.mCurrentBytes != state.mContentLength);
         if (lengthMismatched) {
             if (cannotResume(state)) {
-                throw new StopRequestException(Downloads.Impl.STATUS_CANNOT_RESUME,
+                throw new StopRequestException(STATUS_CANNOT_RESUME,
                         "mismatched content length; unable to resume");
             } else {
-                throw new StopRequestException(getFinalStatusForHttpError(state),
+                throw new StopRequestException(STATUS_HTTP_DATA_ERROR,
                         "closed socket before end of file");
             }
         }
@@ -521,25 +643,22 @@ public class DownloadThread extends Thread {
             values.put(Downloads.Impl.COLUMN_CURRENT_BYTES, state.mCurrentBytes);
             mContext.getContentResolver().update(mInfo.getAllDownloadsUri(), values, null, null);
             if (cannotResume(state)) {
-                throw new StopRequestException(Downloads.Impl.STATUS_CANNOT_RESUME,
+                throw new StopRequestException(STATUS_CANNOT_RESUME,
                         "Failed reading response: " + ex + "; unable to resume", ex);
             } else {
-                throw new StopRequestException(getFinalStatusForHttpError(state),
+                throw new StopRequestException(STATUS_HTTP_DATA_ERROR,
                         "Failed reading response: " + ex, ex);
             }
         }
     }
 
     /**
-     * Read HTTP response headers and take appropriate action, including setting up the destination
-     * file and updating the database.
+     * Prepare target file based on given network response. Derives filename and
+     * target size as needed.
      */
     private void processResponseHeaders(State state, HttpURLConnection conn)
             throws StopRequestException {
-        if (state.mContinuingDownload) {
-            // ignore response headers on resume requests
-            return;
-        }
+        // TODO: fallocate the entire file if header gave us specific length
 
         readResponseHeaders(state, conn);
 
@@ -552,7 +671,7 @@ public class DownloadThread extends Thread {
                 state.mMimeType,
                 mInfo.mDestination,
                 state.mContentLength,
-                mInfo.mIsPublicApi, mStorageManager);
+                mStorageManager);
 
         updateDatabaseFromHeaders(state);
         // check connectivity again now that we know the total size
@@ -604,59 +723,12 @@ public class DownloadThread extends Thread {
         final boolean noSizeInfo = state.mContentLength == -1
                 && (transferEncoding == null || !transferEncoding.equalsIgnoreCase("chunked"));
         if (!mInfo.mNoIntegrity && noSizeInfo) {
-            throw new StopRequestException(Downloads.Impl.STATUS_HTTP_DATA_ERROR,
+            throw new StopRequestException(STATUS_CANNOT_RESUME,
                     "can't know size of download, giving up");
         }
     }
 
-    /**
-     * Check the HTTP response status and handle anything unusual (e.g. not 200/206).
-     */
-    private void handleExceptionalStatus(State state, HttpURLConnection conn, int statusCode)
-            throws StopRequestException {
-        if (statusCode == HTTP_UNAVAILABLE && mInfo.mNumFailed < Constants.MAX_RETRIES) {
-            handleServiceUnavailable(state, conn);
-        }
-
-        if (Constants.LOGV) {
-            Log.i(Constants.TAG, "recevd_status = " + statusCode +
-                    ", mContinuingDownload = " + state.mContinuingDownload);
-        }
-        int expectedStatus = state.mContinuingDownload ? HTTP_PARTIAL : HTTP_OK;
-        if (statusCode != expectedStatus) {
-            handleOtherStatus(state, statusCode);
-        }
-    }
-
-    /**
-     * Handle a status that we don't know how to deal with properly.
-     */
-    private void handleOtherStatus(State state, int statusCode) throws StopRequestException {
-        if (statusCode == HTTP_REQUESTED_RANGE_NOT_SATISFIABLE) {
-            // range request failed. it should never fail.
-            throw new IllegalStateException("Http Range request failure: totalBytes = " +
-                    state.mTotalBytes + ", bytes recvd so far: " + state.mCurrentBytes);
-        }
-        int finalStatus;
-        if (statusCode >= 400 && statusCode < 600) {
-            finalStatus = statusCode;
-        } else if (statusCode >= 300 && statusCode < 400) {
-            finalStatus = Downloads.Impl.STATUS_UNHANDLED_REDIRECT;
-        } else if (state.mContinuingDownload && statusCode == HTTP_OK) {
-            finalStatus = Downloads.Impl.STATUS_CANNOT_RESUME;
-        } else {
-            finalStatus = Downloads.Impl.STATUS_UNHANDLED_HTTP_CODE;
-        }
-        throw new StopRequestException(finalStatus, "http error " +
-                statusCode + ", mContinuingDownload: " + state.mContinuingDownload);
-    }
-
-    /**
-     * Handle a 503 Service Unavailable status by processing the Retry-After header.
-     */
-    private void handleServiceUnavailable(State state, HttpURLConnection conn)
-            throws StopRequestException {
-        state.mCountRetry = true;
+    private void parseRetryAfterHeaders(State state, HttpURLConnection conn) {
         state.mRetryAfter = conn.getHeaderFieldInt("Retry-After", -1);
         if (state.mRetryAfter < 0) {
             state.mRetryAfter = 0;
@@ -669,28 +741,6 @@ public class DownloadThread extends Thread {
             state.mRetryAfter += Helpers.sRandom.nextInt(Constants.MIN_RETRY_AFTER + 1);
             state.mRetryAfter *= 1000;
         }
-
-        throw new StopRequestException(Downloads.Impl.STATUS_WAITING_TO_RETRY,
-                "got 503 Service Unavailable, will retry later");
-    }
-
-    private int getFinalStatusForHttpError(State state) {
-        int networkUsable = mInfo.checkCanUseNetwork();
-        if (networkUsable != DownloadInfo.NETWORK_OK) {
-            switch (networkUsable) {
-                case DownloadInfo.NETWORK_UNUSABLE_DUE_TO_SIZE:
-                case DownloadInfo.NETWORK_RECOMMENDED_UNUSABLE_DUE_TO_SIZE:
-                    return Downloads.Impl.STATUS_QUEUED_FOR_WIFI;
-                default:
-                    return Downloads.Impl.STATUS_WAITING_FOR_NETWORK;
-            }
-        } else if (mInfo.mNumFailed < Constants.MAX_RETRIES) {
-            state.mCountRetry = true;
-            return Downloads.Impl.STATUS_WAITING_TO_RETRY;
-        } else {
-            Log.w(Constants.TAG, "reached max retries for " + mInfo.mId);
-            return Downloads.Impl.STATUS_HTTP_DATA_ERROR;
-        }
     }
 
     /**
@@ -764,52 +814,52 @@ public class DownloadThread extends Thread {
      * Add custom headers for this download to the HTTP request.
      */
     private void addRequestHeaders(State state, HttpURLConnection conn) {
-        conn.addRequestProperty("User-Agent", userAgent());
-
         for (Pair<String, String> header : mInfo.getHeaders()) {
             conn.addRequestProperty(header.first, header.second);
         }
 
+        // Only splice in user agent when not already defined
+        if (conn.getRequestProperty("User-Agent") == null) {
+            conn.addRequestProperty("User-Agent", userAgent());
+        }
+
+        // Defeat transparent gzip compression, since it doesn't allow us to
+        // easily resume partial downloads.
+        conn.setRequestProperty("Accept-Encoding", "identity");
+
         if (state.mContinuingDownload) {
             if (state.mHeaderETag != null) {
                 conn.addRequestProperty("If-Match", state.mHeaderETag);
             }
             conn.addRequestProperty("Range", "bytes=" + state.mCurrentBytes + "-");
-            if (Constants.LOGV) {
-                Log.i(Constants.TAG, "Adding Range header: " +
-                        "bytes=" + state.mCurrentBytes + "-");
-                Log.i(Constants.TAG, "  totalBytes = " + state.mTotalBytes);
-            }
         }
     }
 
     /**
      * Stores information about the completed download, and notifies the initiating application.
      */
-    private void notifyDownloadCompleted(int status, boolean countRetry, int retryAfter,
-            boolean gotData, String filename, String mimeType, String errorMsg) {
-        notifyThroughDatabase(
-                status, countRetry, retryAfter, gotData, filename, mimeType, errorMsg);
-        if (Downloads.Impl.isStatusCompleted(status)) {
+    private void notifyDownloadCompleted(
+            State state, int finalStatus, String errorMsg, int numFailed) {
+        notifyThroughDatabase(state, finalStatus, errorMsg, numFailed);
+        if (Downloads.Impl.isStatusCompleted(finalStatus)) {
             mInfo.sendIntentIfRequested();
         }
     }
 
-    private void notifyThroughDatabase(int status, boolean countRetry, int retryAfter,
-            boolean gotData, String filename, String mimeType, String errorMsg) {
+    private void notifyThroughDatabase(
+            State state, int finalStatus, String errorMsg, int numFailed) {
         ContentValues values = new ContentValues();
-        values.put(Downloads.Impl.COLUMN_STATUS, status);
-        values.put(Downloads.Impl._DATA, filename);
-        values.put(Downloads.Impl.COLUMN_MIME_TYPE, mimeType);
+        values.put(Downloads.Impl.COLUMN_STATUS, finalStatus);
+        values.put(Downloads.Impl._DATA, state.mFilename);
+        values.put(Downloads.Impl.COLUMN_MIME_TYPE, state.mMimeType);
         values.put(Downloads.Impl.COLUMN_LAST_MODIFICATION, mSystemFacade.currentTimeMillis());
-        values.put(Constants.RETRY_AFTER_X_REDIRECT_COUNT, retryAfter);
-        if (!countRetry) {
-            values.put(Constants.FAILED_CONNECTIONS, 0);
-        } else if (gotData) {
-            values.put(Constants.FAILED_CONNECTIONS, 1);
-        } else {
-            values.put(Constants.FAILED_CONNECTIONS, mInfo.mNumFailed + 1);
+        values.put(Downloads.Impl.COLUMN_FAILED_CONNECTIONS, numFailed);
+        values.put(Constants.RETRY_AFTER_X_REDIRECT_COUNT, state.mRetryAfter);
+
+        if (!TextUtils.equals(mInfo.mUri, state.mRequestUri)) {
+            values.put(Downloads.Impl.COLUMN_URI, state.mRequestUri);
         }
+
         // save the error message. could be useful to developers.
         if (!TextUtils.isEmpty(errorMsg)) {
             values.put(Downloads.Impl.COLUMN_ERROR_MSG, errorMsg);
@@ -846,4 +896,19 @@ public class DownloadThread extends Thread {
             return defaultValue;
         }
     }
+
+    /**
+     * Return if given status is eligible to be treated as
+     * {@link android.provider.Downloads.Impl#STATUS_WAITING_TO_RETRY}.
+     */
+    public static boolean isStatusRetryable(int status) {
+        switch (status) {
+            case STATUS_HTTP_DATA_ERROR:
+            case HTTP_UNAVAILABLE:
+            case HTTP_INTERNAL_ERROR:
+                return true;
+            default:
+                return false;
+        }
+    }
 }