* info that contains the table and row we're seeking.
*/
private HRegionLocation locateRegionInMeta(final byte [] parentTable,
final byte [] tableName, final byte [] row, boolean useCache)
throws IOException{
HRegionLocation location = null;
// If supposed to be using the cache, then check it for a possible hit.
// Otherwise, delete any existing cached location so it won't interfere.
if (useCache) {
location = getCachedLocation(tableName, row);
if (location != null) {
return location;
}
} else {
deleteCachedLocation(tableName, row);
}
// build the key of the meta region we should be looking for.
// the extra 9's on the end are necessary to allow "exact" matches
// without knowing the precise region names.
byte [] metaKey = HRegionInfo.createRegionName(tableName, row,
HConstants.NINES);
for (int tries = 0; true; tries++) {
if (tries >= numRetries) {
throw new NoServerForRegionException("Unable to find region for "
+ Bytes.toString(row) + " after " + numRetries + " tries.");
}
try {
// locate the root region
HRegionLocation metaLocation = locateRegion(parentTable, metaKey);
HRegionInterface server =
getHRegionConnection(metaLocation.getServerAddress());
// Query the root region for the location of the meta region
RowResult regionInfoRow = server.getClosestRowBefore(
metaLocation.getRegionInfo().getRegionName(), metaKey,
HConstants.COLUMN_FAMILY);
if (regionInfoRow == null) {
throw new TableNotFoundException(Bytes.toString(tableName));
}
Cell value = regionInfoRow.get(COL_REGIONINFO);
if (value == null || value.getValue().length == 0) {
throw new IOException("HRegionInfo was null or empty in " +
Bytes.toString(parentTable));
}
// convert the row result into the HRegionLocation we need!
HRegionInfo regionInfo = (HRegionInfo) Writables.getWritable(
value.getValue(), new HRegionInfo());
// possible we got a region of a different table...
if (!Bytes.equals(regionInfo.getTableDesc().getName(), tableName)) {
throw new TableNotFoundException(
"Table '" + Bytes.toString(tableName) + "' was not found.");
}
if (regionInfo.isOffline()) {
throw new RegionOfflineException("region offline: " +
regionInfo.getRegionNameAsString());
}
String serverAddress =
Writables.cellToString(regionInfoRow.get(COL_SERVER));
if (serverAddress.equals("")) {
throw new NoServerForRegionException("No server address listed " +
"in " + Bytes.toString(parentTable) + " for region " +
regionInfo.getRegionNameAsString());
}
// instantiate the location
location = new HRegionLocation(regionInfo,
new HServerAddress(serverAddress));
cacheLocation(tableName, location);
return location;
} catch (TableNotFoundException e) {
// if we got this error, probably means the table just plain doesn't