libpqnb's Introduction

libpqnb

Postgres non-blocking libpq connection pool

How to build

make libpqnb.so

If you do not have pg_config installed:

make -DPG_INCLUDEDIR=/your/pg/include/dir libpqnb.so

Usage

All dependencies needed are in:

#include "pqnb.h"

Initialize the connection pool:

struct PQNB_pool *pool;  
const char conninfo[] = "postgresql:///yourdbname?host=/var/run/postgresql";  
uint16_t num_connections = 32;  
pool = PQNB_pool_init(conninfo, num_connections);

Get pool epoll file descriptor:

const union PQNB_pool_info *info;  
info = PQNB_pool_get_info(pool, PQNB_INFO_EPOLL_FD);

Run pool:

/* This call doesn't block, you may select/epoll_wait the pool epoll_fd */  
/* you need to call this function any time the library has any data to proccess */  
/* we know when there's data ready when epoll_fd is ready to read POLLIN / EPOLLIN */  
/* see examples/test.c */  
PQNB_pool_run(pool);

Run a query:

/* just a struct example */  
struct query_counter { uint64_t count; };  
  
/* callback */  
void  
query_callback(PGresult *res,  
              void *user_data,   
              char *error_msg,  
              bool timeout)  
{  
  struct query_counter *queries_counter;  
  
  /*  
   * ignoring compiler warnings  
   */  
  (void) res;  
  
  if (timeout)  
    {  
      printf("timeout\n");  
      return;  
    }  
  
  if (NULL != error_msg)  
    {  
      printf("%s", error_msg);  
      return;  
    }  
  
  if (PGRES_TUPLES_OK == PQresultStatus(res))  
    {  
      assert(NULL != user_data);  
      queries_counter = user_data;  
      queries_counter->count++;  
    }  
  else  
    printf("query failed\n");  
}    
  
/* querying */
PQNB_pool_query(pool, "SELECT * FROM version()",  
                query_callback, &counter);

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