main.c

#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <time.h>
#include <fcntl.h>

#define READ_BUFFER (2048)
#define FILE_PATH ("test.txt")

int testRead(char* file_path);
int testFread(char* file_path);
int testFreadWithBuffer(char* file_path);

int main()
{
    testRead(FILE_PATH);
    testFread(FILE_PATH);
    testFreadWithBuffer(FILE_PATH);

    return 0;
}


int testRead(char* file_path)
{
    clock_t begin = clock();
    int fd = open(file_path, O_RDONLY);
    if(fd < 0)
    {
        printf("can't read test file %s\n", FILE_PATH);
        return errno;
    }

    char buffer[READ_BUFFER];
    int length = sizeof(buffer);
    int read_count;
    while((read_count = read(fd, buffer, length)) != 0)
    {
        //printBuffer(buffer, read_count);
    }

    close(fd);
    clock_t end = clock();
    double time_spent = (double)(end - begin) / CLOCKS_PER_SEC;

    printf("%s\t%lf\n", __func__, time_spent);
}


int testFread(char* file_path)
{
    clock_t begin = clock();

    FILE* file = fopen(file_path, "r");
    if(file == NULL)
    {
        printf("can't read test file %s\n", FILE_PATH);
        return errno;
    }

    char buffer[READ_BUFFER];
    int length = sizeof(buffer);
    int read_count;
    while((read_count = fread(buffer, 1, length, file)) != 0)
    {
        // printBuffer(buffer, read_count);
    }
    fclose(file);

    clock_t end = clock();
    double time_spent = (double)(end - begin) / CLOCKS_PER_SEC;
    printf("%s\t%lf\n", __func__, time_spent);
}

int testFreadWithBuffer(char* file_path)
{


    clock_t begin = clock();
    FILE* file = fopen(file_path, "r");
    if(file == NULL)
    {
        printf("can't read test file %s\n", FILE_PATH);
        return errno;
    }

    char buffer[READ_BUFFER];
    int length = sizeof(buffer);
    setvbuf(file, NULL, _IOFBF, READ_BUFFER*4 );    // large buffer
    int read_count;
    while((read_count = fread(buffer, 1, length, file)) != 0)
    {
        // printBuffer(buffer, read_count);
    }
    fclose(file);

    clock_t end = clock();
    double time_spent = (double)(end - begin) / CLOCKS_PER_SEC;
    printf("%s\t%lf\n", __func__, time_spent);
}


void printBuffer(char* buffer, int count)
{
    int length = sizeof(buffer);
    if(count == length)
    {
        printf("%s", buffer);
    }
    else
    {
        for(int i=0; i< count; i++)
            printf("%c", buffer[i]);
    }
}