/**
* $Id: KfsSample.java 127 2008-08-13 19:19:32Z sriramsrao $
*
* Created 2007/08/25
* Author: Sriram Rao
*
* Copyright 2007 Kosmix Corp.
*
* This file is part of Kosmos File System (KFS).
*
* 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,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License.
*
* \brief A Sample Java program to access KFSAccess APIs. To run this
* program, you need:
* - kfs.jar in your CLASSPATH
* - libkfs_access.so in your LD_LIBRARY_PATH
* - a KFS deployment
*/
import java.io.*;
import java.net.*;
import java.util.Random;
public class KfsSample
{
public static void main(String args[]) {
if (args.length < 1) {
System.out.println("Usage: KfsTest <meta server> <port>");
System.exit(1);
}
try {
// From the command line, get the location of the meta-server
int port = Integer.parseInt(args[1].trim());
// Initialize a KfsAccess object. The KfsAccess object is
// the glue code that gets us into KFS world.
//
KfsAccess kfsAccess = new KfsAccess(args[0], port);
String basedir = new String("jtest");
// Make a test directory where we can do something
if (!kfsAccess.kfs_exists(basedir)) {
if (kfsAccess.kfs_mkdirs(basedir) != 0) {
System.out.println("Unable to mkdir");
System.exit(1);
}
}
// What we just created better be a directory
if (!kfsAccess.kfs_isDirectory(basedir)) {
System.out.println("KFS doesn't think " + basedir + " is a dir!");
System.exit(1);
}
// Create a simple file with default replication (at most 3)
String path = new String(basedir + "/foo.1");
KfsOutputChannel outputChannel;
// outputChannel implements a WriteableChannel interface;
// it is our handle to subsequent I/O on the file.
if ((outputChannel = kfsAccess.kfs_create(path)) == null) {
System.out.println("Unable to call create");
System.exit(1);
}
// Get the directory listings
String [] entries;
if ((entries = kfsAccess.kfs_readdir(basedir)) == null) {
System.out.println("Readdir failed");
System.exit(1);
}
System.out.println("Readdir returned: ");
for (int i = 0; i < entries.length; i++) {
System.out.println(entries[i]);
}
// write something to the file
int numBytes = 2048;
char [] dataBuf = new char[numBytes];
generateData(dataBuf, numBytes);
String s = new String(dataBuf);
byte[] buf = s.getBytes();
int res = outputChannel.write(ByteBuffer.wrap(buf, 0, buf.length));
if (res != buf.length) {
System.out.println("Was able to write only: " + res);
}
// flush out the changes
outputChannel.sync();
// Close the file-handle
outputChannel.close();
// Determine the file-size
long sz = kfsAccess.kfs_filesize(path);
if (sz != buf.length) {
System.out.println("System thinks the file's size is: " + sz);
}
// rename the file
String npath = new String(basedir + "/foo.2");
kfsAccess.kfs_rename(path, npath);
if (kfsAccess.kfs_exists(path)) {
System.out.println(path + " still exists after rename!");
System.exit(1);
}
KfsOutputChannel outputChannel1 = kfsAccess.kfs_create(path);
if (outputChannel1 != null) {
outputChannel1.close();
}
if (!kfsAccess.kfs_exists(path)) {
System.out.println(path + " doesn't exist");
System.exit(1);
}
// try to rename and don't allow overwrite
if (kfsAccess.kfs_rename(npath, path, false) == 0) {
System.out.println("Rename with overwrite disabled succeeded!");
System.exit(1);
}
// Remove the file
kfsAccess.kfs_remove(path);
// Verify that it is gone
if (!kfsAccess.kfs_isFile(npath)) {
System.out.println(npath + " is not a normal file!");
System.exit(1);
}
// Re-open the file to read something. For reads/writes,
// Kfs provides a readable/writeable byte channel interface.
KfsInputChannel inputChannel = kfsAccess.kfs_open(npath);
if (inputChannel == null) {
System.out.println("open on " + npath + "failed!");
System.exit(1);
}
// read some bytes
buf = new byte[128];
res = inputChannel.read(ByteBuffer.wrap(buf, 0, 128));
// Verify what we read matches what we wrote
s = new String(buf);
for (int i = 0; i < 128; i++) {
if (dataBuf[i] != s.charAt(i)) {
System.out.println("Data mismatch at char: " + i);
}
}
// seek to offset 40. The KfsInputChannel allows seeking;
// this is an extension to the basic readablebytechannel api.
inputChannel.seek(40);
// Seek and verify that we are we think we are
sz = inputChannel.tell();
if (sz != 40) {
System.out.println("After seek, we are at: " + sz);
}
inputChannel.close();
// remove the file
kfsAccess.kfs_remove(npath);
// remove the dir
if (kfsAccess.kfs_rmdir(basedir) < 0) {
System.out.println("unable to remove: " + basedir);
System.exit(1);
}
System.out.println("All done...Test passed!");
} catch (Exception e) {
e.printStackTrace();
System.out.println("Unable to setup KfsAccess");
System.exit(1);
}
}
private static Random randGen = new Random(100);
private static void generateData(char buf[], int numBytes)
{
int i;
for (i = 0; i < numBytes; i++) {
buf[i] = (char) ('a' + (randGen.nextInt(26)));
}
}
}
