hdfs_read.c

来自「hadoop:Nutch集群平台」· C语言 代码 · 共 66 行

/**
 * Copyright 2005 The Apache Software Foundation
 *
 * 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.
 */

#include "hdfs.h" 

int main(int argc, char **argv) {

    if (argc != 4) {
        fprintf(stderr, "Usage: hdfs_read <filename> <filesize> <buffersize>\n");
        exit(-1);
    }
    
    hdfsFS fs = hdfsConnect("default", 0);
    if (!fs) {
        fprintf(stderr, "Oops! Failed to connect to hdfs!\n");
        exit(-1);
    } 
 
    const char* rfile = argv[1];
    tSize fileTotalSize = strtoul(argv[2], NULL, 10);
    tSize bufferSize = strtoul(argv[3], NULL, 10);
   
    hdfsFile readFile = hdfsOpenFile(fs, rfile, O_RDONLY, bufferSize, 0, 0);
    if (!readFile) {
        fprintf(stderr, "Failed to open %s for writing!\n", rfile);
        exit(-2);
    }

    // data to be written to the file
    char* buffer = malloc(sizeof(char) * bufferSize);
    if(buffer == NULL) {
        return -2;
    }
    
    // read from the file
    tSize curSize = bufferSize;
    for (; curSize == bufferSize;) {
        curSize = hdfsRead(fs, readFile, (void*)buffer, curSize);
    }
    

    free(buffer);
    hdfsCloseFile(fs, readFile);
    hdfsDisconnect(fs);

    return 0;
}

/**
 * vim: ts=4: sw=4: et:
 */