algorithm - Write to multiple files based on name, in C

Question

The code below works and writes all logs to one fixed file:

    snprintf(filename, 128, "/var/log/api_record.log");

    fp = fopen(filename, "a+");

    if(fp){
        PLIST_FOR_EACH_SAFE(&temp, record, tmp, list){
            PLIST_DEL(&temp, &record->list);
            fprintf(fp, "%.*s
", record->buflen, record->buf);
            free(record->buf);
            free(record);
        }
        fflush(fp);
        fclose(fp);
    }

Now I'm trying to get, say, host_name, and write each record to a different file, named by the record's host_name.

    if(fp){
        PLIST_FOR_EACH_SAFE(&temp, record, tmp, list){
            PLIST_DEL(&temp, &record->list);
            host_name = record->meta;
            fprintf(fp, "%.*s
", record->buflen, record->buf); // The question is what's the fp?
            free(record->buf);
            free(record);
        }
        fflush(fp);
        fclose(fp);
    }

But I'm not sure how to maintain the fp's here. I can open and close a file with the desired filename with each record, like below, but it's costly. (do one fopen() per iteration of the loop)

    snprintf(filename, 128, "/var/log/%s.log", host_name);

    fp = fopen(filename, "a+");

Or possibly, traverse through the records as a preprocessing step and open the host_name named files beforehand, then map the host_name's to the fps through some hashmap? But that also sounds quite ugly.

How can I efficiently do this?

question from:https://stackoverflow.com/questions/65832314/write-to-multiple-files-based-on-name-in-c

Answer 1

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