io.polaris.core.guid.LocalNode Maven / Gradle / Ivy
package io.polaris.core.guid;
import io.polaris.core.os.OS;
import java.io.RandomAccessFile;
import java.net.InetAddress;
import java.nio.channels.FileLock;
/**
* @author Qt
* @since 1.8
*/
public class LocalNode {
public static int nextNodeId(String appName, int bizSize) {
if (bizSize <= 8 || bizSize > 16) {
throw new IllegalArgumentException();
}
int nodeId = 0;
String tmpdir = System.getProperty("java.io.tmpdir");
final String file = tmpdir + "/.guid." + appName + ".lck";
try (RandomAccessFile raf = new RandomAccessFile(file, "rw")) {
FileLock lock = null;
while (true) {
try {
lock = raf.getChannel().lock();
break;
} catch (Throwable e) {
}
}
try {
if (raf.length() >= 4) {
nodeId = raf.readInt() + 1;
raf.seek(0);
raf.writeInt(nodeId);
} else {
raf.writeInt(nodeId);
}
} finally {
if (lock != null) {
lock.release();
}
}
} catch (Throwable e) {
System.err.println("cannot access file : " + file);
e.printStackTrace(System.err);
}
int addr = 0;
try {
String firstIp = OS.getFirstIp();
if (firstIp == null){
byte[] address = InetAddress.getLocalHost().getAddress();
addr = address[address.length - 1];
}else{
String[] arr = firstIp.split("\\.");
addr = Integer.parseInt(arr[arr.length - 1]);
}
} catch (Throwable e) {
System.err.println("cannot read InetAddress!");
e.printStackTrace(System.err);
}
return ((addr & 0xFF) << (bizSize - 8)) | (nodeId & (-1 ^ (-1 << (bizSize - 8))));
}
}