node.js在C写入时读取txt文件

Question

I want to my node.js function reading from file while c program writing in it at same time if that is not impossible. Node.js function can't read while c writing, I want to remove that lock. Also I need to node function doesn't stop until read 'End of file!'.

c program:

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

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

    int simulationLength,simulationStep,simulationStepNum,i,time;
    FILE *f;

    if(argc != 3) {
        printf("Bad input!\n");
        return 1;
    }



    simulationLength = atoi(argv[1]);
    simulationStep = atoi(argv[2]);

    simulationStepNum = simulationLength/simulationStep;
    f=fopen("exit.dat","w");

    for(i=0;i<simulationStepNum;i++) {
        time = rand()%10;
        fprintf(f,"TStep %d, Time=%d\n",i,time);
        sleep(time);
        if(i%10 == 0)
            fprintf(f,"Internal error!\n");
    }
    fprintf(f,"End of file!\n");
    fclose(f);
} 

node.js function:

var readline = require('readline');
var fs = require('fs');

module.exports = function() {
    var file = 'app/webmus/app/wemus-cluster-simulation/exit.dat';
    var eof = 'End of file!';  

    var lineReader = readline.createInterface({
        input: fs.createReadStream(file)
    });

    lineReader.on('line', function(line) {
        if (line == eof) lineReader.close();
        console.log(line);
    }).on('close',function(){
        process.exit(0);
    });;   
}  

Answer 1

You can also push changes to file by flushing contents:

for(i=0;i<simulationStepNum;i++) {
    time = rand()%10;
    fprintf(f,"TStep %d, Time=%d\n",i,time);

    // flush data from buffers to disk.
    fflush(f);

    sleep(time);
    if(i%10 == 0)
        fprintf(f,"Internal error!\n");
}

I'm positive, this should resolve your issue. Again, if you are on *nix environment, named pipes are best for this kind of work.