fdatasync()????????????????

By MD on Mar 4, 2008 | In db4o, ??? | Send feedback »

???????????????????????????????????????????????????????db4o???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

?????????????????????????????????????????????????????????????????

POSIX???OS???fsync()??????fdatasync()???????????????????????????????????????????????????????????????????????fsync()???????????fdatasync()??????????10-20%??????????????

????????db4o?????????db4o?IoAdapter?????????I/O??????????????????JNI?POSIX?fdatasync()????????????

?????????????IoAdapter??????????????????????

Code:

#include <jni.h>
#include "LinuxIoAdapter.h"
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
 
/*
 * Class:     LinuxIoAdapter
 * Method:    openFile
 * Signature: (Ljava/lang/String;ZJ)J
 */
JNIEXPORT jint JNICALL Java_LinuxIoAdapter_openFile
  (JNIEnv *env, jclass jc, jstring path, jboolean lockfile, jlong initiallength)
{
    printf("openFile\n");
    const jbyte *filename = (*env)->GetStringUTFChars(env, path, NULL);
 
    if(filename == NULL){
        return 0; // OutOfMemoryError or NULL value
    }
 
    int fd = open(filename, O_RDWR|O_CREAT, 0644);
 
    if(fd < 0){
        printf("open failed\n");
    }
 
    (*env)->ReleaseStringChars(env, path, NULL);
 
    return fd;
 
}
 
/*
 * Class:     LinuxIoAdapter
 * Method:    closeFile
 * Signature: (J)V
 */
JNIEXPORT void JNICALL Java_LinuxIoAdapter_closeFile
  (JNIEnv * env, jclass jc, jint handle)
{
    printf("closeFile\n");
    if(close(handle) < 0){
        printf("close failed\n");
    }
 
}
 
/*
 * Class:     LinuxIoAdapter
 * Method:    getLength
 * Signature: (J)J
 */
JNIEXPORT jlong JNICALL Java_LinuxIoAdapter_getLength
  (JNIEnv *env, jclass jc, jint handle)
{
    struct stat st;
    fstat(handle, &st);
    return st.st_size;
}
 
/*
 * Class:     LinuxIoAdapter
 * Method:    read
 * Signature: (J[BI)I
 */
JNIEXPORT jint JNICALL Java_LinuxIoAdapter_read
  (JNIEnv *env, jclass jc, jint handle, jbyteArray bytes, jint length)
{
    
    jbyte buf[length];
 
    ssize_t n = read(handle, &buf, length);
 
    if(n != length)
        printf("read failed: %i->%i", length, n);
 
    (*env)->SetByteArrayRegion(env, bytes, 0, length, buf);
 
    return n;
}
 
/*
 * Class:     LinuxIoAdapter
 * Method:    seek
 * Signature: (JJ)V
 */
JNIEXPORT void JNICALL Java_LinuxIoAdapter_seek
  (JNIEnv *env, jclass jc, jint handle, jlong pos)
{
 
    lseek(handle, pos, SEEK_SET);
}
 
/*
 * Class:     LinuxIoAdapter
 * Method:    sync
 * Signature: (J)V
 */
JNIEXPORT void JNICALL Java_LinuxIoAdapter_sync
  (JNIEnv *env, jclass jc, jint handle)
{
    fdatasync(handle);
    //fsync(handle);
}
 
/*
 * Class:     LinuxIoAdapter
 * Method:    write
 * Signature: (J[BI)V
 */
JNIEXPORT void JNICALL Java_LinuxIoAdapter_write
  (JNIEnv *env, jclass jc, jint handle, jbyteArray bytes, jint length)
{
    jbyte buf[length];
 
    (*env)->GetByteArrayRegion(env, bytes, 0, length, buf);
 
    ssize_t n = write(handle, &buf, length);
 
    if(n != length)
        printf("read failed: %i->%i", length, n);
}
Tags: fdatasync, fsync, ioadapter, jni, posix

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