JNI学习2

简单的ByteBuffer调用和使用MPI交换参数

程序设计:用ByteBuffer.allocateDirect() 接口分配两个等长的内存空间(addr1和addr2),在JNI中使用GetDirectBufferAddress接口获得两个内存空间的地址,通过MPI的MPI_Isend/MPI_Recv接口,将addr1中的数据传递到addr2中。整个MPI在单进程中执行。

ByteBuff.java

View Code
 1 import java.nio.ByteBuffer;
 2 
 3 public class ByteBuff {
 4 
 5     static {
 6         System.loadLibrary("buff");
 7     }
 8 
 9     public native void printBuff(ByteBuffer sbf, ByteBuffer rbf);
10 
11     public static void main(String[] args) {
12         ByteBuffer bf = ByteBuffer.allocateDirect(10);
13         ByteBuffer rbf = ByteBuffer.allocateDirect(10);
14         byte bbs[] = "abc".getBytes();
15         bf.put(bbs);
16         System.out.println("Before swap " + (char) (rbf).get());
17         (new ByteBuff()).printBuff(bf, rbf);
18         System.out.println("Before swap " + (char) (rbf).get());
19     }
20 }

ByteBuff.c

View Code
 1 #include "ByteBuff.h"
 2 #include <stdio.h>
 3 #include <stdlib.h>
 4 #include <mpi.h>
 5 
 6 JNIEXPORT void JNICALL Java_ByteBuff_printBuff (JNIEnv *env, jobject jobj, jobject sbuf,jobject rbuf) {
 7     jbyte* sbufp=(*env)->GetDirectBufferAddress(env,sbuf);
 8     jbyte* rbufp=(*env)->GetDirectBufferAddress(env,rbuf);
 9 
10     MPI_Request sreq,rreq;
11     MPI_Status sstatus,rstatus;
12     MPI_Init(NULL,NULL);
13     MPI_Isend(sbufp,3,MPI_BYTE,0,0,MPI_COMM_WORLD,&sreq);
14     MPI_Recv(rbufp,3,MPI_BYTE,0,0,MPI_COMM_WORLD,&rstatus);
15     MPI_Wait(&sreq,&sstatus);
16     MPI_Finalize();
17 
18     (*env)->ReleasePrimitiveArrayCritical(env,sbuf,sbufp,0);
19     (*env)->ReleasePrimitiveArrayCritical(env,rbuf,rbufp,0);
20 }

编译动态库的时候需要链接MPI的静态库(本文使用MVAPICH 1.8.x),编译命令为

gcc -std=c99 -shared -fPIC -I /usr/local/mvapich/include/ -I /usr/local/jdk1.6.0_30/include/ -I /usr/local/jdk1.6.0_30/include/linux/ -I /usr/local/ ByteBuff.c -o libbuff.so  -lpthread /usr/local/mvapich/lib/libmpich.a /usr/local/mvapich/lib/libopa.a /usr/local/mvapich/lib/libmpl.a -lrt -lpthread /usr/local/mvapich/lib/libmpich.a /usr/local/mvapich/lib/libopa.a /usr/local/mvapich/lib/libmpl.a -lrt

执行结果

1 $ mpiexec -n 1 java -Djava.library.path=. ByteBuff
2 Before swap 
3 Before swap b

 

posted @ 2013-04-11 14:41  asdffdas  阅读(814)  评论(0编辑  收藏  举报