package com.android.emailcommon.provider;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
/**
* {@link EmailContent}-like base class for change log tables.
* Accounts that upsync message changes require a change log to track local changes between upsyncs.
* A single instance of this class (or subclass) represents one change to upsync to the server.
* This object may actually correspond to multiple rows in the table.
* This class (and subclasses) also contains constants for the table columns and values stored in
* the DB. The base class contains the ones common to all change logs.
*/
public abstract class MessageChangeLogTable {
// DB columns. Note that this class (and subclasses) use some denormalized columns
// (e.g. accountKey) for simplicity at query time and debugging ease.
/** Column name for the row key; this is an autoincrement key. */
public static final String ID = "_id";
/** Column name for a foreign key into Message for the message that's moving. */
public static final String MESSAGE_KEY = "messageKey";
/** Column name for the server-side id for messageKey. */
public static final String SERVER_ID = "messageServerId";
/** Column name for a foreign key into Account for the message that's moving. */
public static final String ACCOUNT_KEY = "accountKey";
/** Column name for a status value indicating where we are with processing this move request. */
public static final String STATUS = "status";
// Status values.
/** Status value indicating this move has not yet been unpsynced. */
public static final int STATUS_NONE = 0;
public static final String STATUS_NONE_STRING = String.valueOf(STATUS_NONE);
/** Status value indicating this move is being upsynced right now. */
public static final int STATUS_PROCESSING = 1;
public static final String STATUS_PROCESSING_STRING = String.valueOf(STATUS_PROCESSING);
/** Status value indicating this move failed to upsync. */
public static final int STATUS_FAILED = 2;
public static final String STATUS_FAILED_STRING = String.valueOf(STATUS_FAILED);
/** Selection string for querying this table. */
private static final String SELECTION_BY_ACCOUNT_KEY_AND_STATUS =
ACCOUNT_KEY + "=? and " + STATUS + "=?";
/** Selection string prefix for deleting moves for a set of messages. */
private static final String SELECTION_BY_MESSAGE_KEYS_PREFIX = MESSAGE_KEY + " in (";
protected final long mMessageKey;
protected final String mServerId;
protected long mLastId;
protected MessageChangeLogTable(final long messageKey, final String serverId, final long id) {
mMessageKey = messageKey;
mServerId = serverId;
mLastId = id;
}
public final long getMessageId() {
return mMessageKey;
}
public final String getServerId() {
return mServerId;
}
/**
* Update status of all change entries for an account:
* - {@link #STATUS_NONE} -> {@link #STATUS_PROCESSING}
* - {@link #STATUS_PROCESSING} -> {@link #STATUS_FAILED}
* @param cr A {@link ContentResolver}.
* @param uri The content uri for this table.
* @param accountId The account we want to update.
* @return The number of change entries that are now in {@link #STATUS_PROCESSING}.
*/
private static int startProcessing(final ContentResolver cr, final Uri uri,
final String accountId) {
final String[] args = new String[2];
args[0] = accountId;
final ContentValues cv = new ContentValues(1);
// First mark anything that's still processing as failed.
args[1] = STATUS_PROCESSING_STRING;
cv.put(STATUS, STATUS_FAILED);
cr.update(uri, cv, SELECTION_BY_ACCOUNT_KEY_AND_STATUS, args);
// Now mark all unprocessed messages as processing.
args[1] = STATUS_NONE_STRING;
cv.put(STATUS, STATUS_PROCESSING);
return cr.update(uri, cv, SELECTION_BY_ACCOUNT_KEY_AND_STATUS, args);
}
/**
* Query for all move records that are in {@link #STATUS_PROCESSING}.
* Note that this function assumes the underlying table uses an autoincrement id key: it assumes
* that ascending id is the same as chronological order.
* @param cr A {@link ContentResolver}.
* @param uri The content uri for this table.
* @param projection The projection to use for this query.
* @param accountId The account we want to update.
* @return A {@link android.database.Cursor} containing all rows, in id order.
*/
private static Cursor getRowsToProcess(final ContentResolver cr, final Uri uri,
final String[] projection, final String accountId) {
final String[] args = { accountId, STATUS_PROCESSING_STRING };
return cr.query(uri, projection, SELECTION_BY_ACCOUNT_KEY_AND_STATUS, args, ID + " ASC");
}
/**
* Create a selection string for all messages in a set.
* @param messageKeys The set of messages we're interested in.
* @param count The number of messages we're interested in.
* @return The selection string for these messages.
*/
private static String getSelectionForMessages(final long[] messageKeys, final int count) {
final StringBuilder sb = new StringBuilder(SELECTION_BY_MESSAGE_KEYS_PREFIX);
for (int i = 0; i < count; ++i) {
if (i != 0) {
sb.append(",");
}
sb.append(messageKeys[i]);
}
sb.append(")");
return sb.toString();
}
/**
* Delete all rows for a set of messages. Used to clear no-op changes (i.e. multiple rows for
* a message that reverts it to the original state) and after successful upsync.
* @param cr A {@link ContentResolver}.
* @param uri The content uri for this table.
* @param messageKeys The messages to clear.
* @param count The number of message keys.
* @return The number of rows deleted from the DB.
*/
protected static int deleteRowsForMessages(final ContentResolver cr, final Uri uri,
final long[] messageKeys, final int count) {
if (count == 0) {
return 0;
}
return cr.delete(uri, getSelectionForMessages(messageKeys, count), null);
}
/**
* Set the status value for a set of messages.
* @param cr A {@link ContentResolver}.
* @param uri The {@link Uri} for the update.
* @param messageKeys The messages to update.
* @param count The number of messageKeys.
* @param status The new status value for the messages.
* @return The number of rows updated.
*/
private static int updateStatusForMessages(final ContentResolver cr, final Uri uri,
final long[] messageKeys, final int count, final int status) {
if (count == 0) {
return 0;
}
final ContentValues cv = new ContentValues(1);
cv.put(STATUS, status);
return cr.update(uri, cv, getSelectionForMessages(messageKeys, count), null);
}
/**
* Set a set of messages to status = retry.
* @param cr A {@link ContentResolver}.
* @param uri The {@link Uri} for the update.
* @param messageKeys The messages to update.
* @param count The number of messageKeys.
* @return The number of rows updated.
*/
protected static int retryMessages(final ContentResolver cr, final Uri uri,
final long[] messageKeys, final int count) {
return updateStatusForMessages(cr, uri, messageKeys, count, STATUS_NONE);
}
/**
* Set a set of messages to status = failed.
* @param cr A {@link ContentResolver}.
* @param uri The {@link Uri} for the update.
* @param messageKeys The messages to update.
* @param count The number of messageKeys.
* @return The number of rows updated.
*/
protected static int failMessages(final ContentResolver cr, final Uri uri,
final long[] messageKeys, final int count) {
return updateStatusForMessages(cr, uri, messageKeys, count, STATUS_FAILED);
}
/**
* Start processing our table and get a {@link Cursor} for the rows to process.
* @param cr A {@link ContentResolver}.
* @param uri The {@link Uri} for the update.
* @param projection The projection to use for our read.
* @param accountId The account we're interested in.
* @return A {@link Cursor} with the change log rows we're interested in.
*/
protected static Cursor getCursor(final ContentResolver cr, final Uri uri,
final String[] projection, final long accountId) {
final String accountIdString = String.valueOf(accountId);
if (startProcessing(cr, uri, accountIdString) <= 0) {
return null;
}
return getRowsToProcess(cr, uri, projection, accountIdString);
}
}