/**
* @param fs
* @param hTableDescriptor
* @param tableDir
* @param status
* @return Descriptor file or null if we failed write.
* @throws IOException
*/
private static Path writeTableDescriptor(
final FileSystem fs,
final HTableDescriptor hTableDescriptor,
final Path tableDir,
final FileStatus status)
throws IOException {
// Get temporary dir into which we'll first write a file to avoid
// half-written file phenomeon.
Path tmpTableDir = new Path(tableDir, ".tmp");
// What is current sequenceid? We read the current sequenceid from
// the current file. After we read it, another thread could come in and
// compete with us writing out next version of file. The below retries
// should help in this case some but its hard to do guarantees in face of
// concurrent schema edits.
int currentSequenceid = status == null ? 0 : getTableInfoSequenceid(status.getPath());
int sequenceid = currentSequenceid;
// Put arbitrary upperbound on how often we retry
int retries = 10;
int retrymax = currentSequenceid + retries;
Path tableInfoPath = null;
do {
sequenceid += 1;
Path p = getTableInfoFileName(tmpTableDir, sequenceid);
if (fs.exists(p)) {
LOG.debug(p + " exists; retrying up to " + retries + " times");
continue;
}
try {
writeHTD(fs, p, hTableDescriptor);
tableInfoPath = getTableInfoFileName(tableDir, sequenceid);
if (!fs.rename(p, tableInfoPath)) {
throw new IOException("Failed rename of " + p + " to " + tableInfoPath);
}
} catch (IOException ioe) {
// Presume clash of names or something; go around again.
LOG.debug("Failed write and/or rename; retrying", ioe);
if (!FSUtils.deleteDirectory(fs, p)) {
LOG.warn("Failed cleanup of " + p);
}
tableInfoPath = null;
continue;
}
// Cleanup old schema file.
if (status != null) {
if (!FSUtils.deleteDirectory(fs, status.getPath())) {
LOG.warn("Failed delete of " + status.getPath() + "; continuing");
}
}
break;
} while (sequenceid < retrymax);
return tableInfoPath;
}
/** Deletes a table's directory from the file system if exists. Used in unit tests. */
public static void deleteTableDescriptorIfExists(String tableName, Configuration conf)
throws IOException {
FileSystem fs = FSUtils.getCurrentFileSystem(conf);
FileStatus status = getTableInfoPath(fs, FSUtils.getRootDir(conf), tableName);
// The below deleteDirectory works for either file or directory.
if (status != null && fs.exists(status.getPath())) {
FSUtils.deleteDirectory(fs, status.getPath());
}
}