cfgdb

A configuration file "database" using ZeroMQ and cJSON to parse configuration files.

Supports multiple configuration files by abstracting config paths into names that must be requested by clients. ZeroMQ can be used to create peer-to-peer (P2P) or to build brokers which can distribute and proxy requests.

Uses basic request/response system, no fancy protocols. Also uses libzmq, not czmq, and the message API, not raw zmq sockets.

Building

git clone https://github.com/caojohnny/cfgdb.git
cd cfgdb
mkdir build
cd build
cmake ..
make

This is a library built with C99. It does nothing on its own. You may use it by including cfgdb.h.

Demo

Client source:

#include <stdio.h>
#include "cfgdb.h"

int main() {
    cfgdb_client_ctx *client = cfgdb_new_client("tcp://localhost:5000", "config");
    printf("double=%f\n", cfgdb_get_double(client, "double"));
    cfgdb_destroy_client(client);
}

Server source:

#include "cfgdb.h"
#include <pthread.h>

void *start_server(void *arg) {
    cfgdb_begin_server("tcp://*:5000");
    return NULL;
}

int main() {
    pthread_t *pthread;
    pthread_create(pthread, NULL, start_server, NULL);

    cfgdb_server_ctx *server_ctx;
    do {
        server_ctx = cfgdb_get_server();
    } while (server_ctx == NULL);
    cfgdb_add_cfg(server_ctx, "config", "./config.json");

    pthread_join(*pthread, NULL);
}

Notes

• Only supports top-level configuration keys
• Only supports JSON

---

Literally spent a total of 10 hours on 3 trivial issues:

• Hashtable BAD_ACCESS due to malloc of a pointer instead of the value of the pointer
• Hashtable was not getting rehashed when it got resized because I was iterating a fresh calloc'd array instead of the old_array
• Server main loop was getting a BAD_ACCESS due to a cJSON instance being put inside of the response, which would get freed. Had to use the AddItemReference instead

Credits

Built with CLion

Uses ZeroMQ as the messaging library and cJSON as the JSON library.