src/lib-ldap/ldap-connection-pool.c

/* Copyright (c) 2016-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "llist.h"
#include "ldap-private.h"
#include "ldap-connection-pool.h"

struct ldap_connection_pool {
    struct ldap_connection_list *conn_list;
    unsigned int conn_count;

    unsigned int max_connections;
};

static void ldap_connection_list_remove(struct ldap_connection_pool *pool,
                    struct ldap_connection_list *list)
{
    DLLIST_REMOVE(&pool->conn_list, list);
    pool->conn_count--;

    ldap_connection_deinit(&list->conn);
    i_free(list);
}

static void
ldap_connection_pool_shrink_to(struct ldap_connection_pool *pool,
                   unsigned int max_count)
{
    struct ldap_connection_list *list, *next;

    list = pool->conn_list;
    for (; list != NULL && pool->conn_count > max_count; list = next) {
        next = list->next;
        if (list->refcount == 0)
            ldap_connection_list_remove(pool, list);
    }
}

struct ldap_connection_pool *
ldap_connection_pool_init(unsigned int max_connections)
{
    struct ldap_connection_pool *pool;

    pool = i_new(struct ldap_connection_pool, 1);
    pool->max_connections = max_connections;
    return pool;
}

void ldap_connection_pool_deinit(struct ldap_connection_pool **_pool)
{
    struct ldap_connection_pool *pool = *_pool;

    *_pool = NULL;

    ldap_connection_pool_shrink_to(pool, 0);
    i_assert(pool->conn_list == NULL);
    i_free(pool);
}

int ldap_connection_pool_get(struct ldap_connection_pool *pool,
                 struct ldap_client *client,
                 const struct ldap_client_settings *set,
                 struct ldap_connection_list **list_r,
                 const char **error_r)
{
    struct ldap_connection_list *list;
    struct ldap_connection *conn;

    for (list = pool->conn_list; list != NULL; list = list->next) {
        if (ldap_connection_have_settings(list->conn, set)) {
            list->refcount++;
            *list_r = list;
            return 0;
        }
    }
    if (ldap_connection_init(client, set, &conn, error_r) < 0)
        return -1;

    list = i_new(struct ldap_connection_list, 1);
    list->conn = conn;
    list->refcount++;

    DLLIST_PREPEND(&pool->conn_list, list);
    pool->conn_count++;

    ldap_connection_pool_shrink_to(pool, pool->max_connections);
    *list_r = list;
    return 0;
}

void ldap_connection_pool_unref(struct ldap_connection_pool *pool,
                struct ldap_connection_list **_list)
{
    struct ldap_connection_list *list = *_list;

    *_list = NULL;

    i_assert(list->refcount > 0);

    if (--list->refcount == 0)
        ldap_connection_pool_shrink_to(pool, pool->max_connections);
}

bool ldap_connection_pool_have_references(struct ldap_connection_pool *pool)
{
    struct ldap_connection_list *list;

    for (list = pool->conn_list; list != NULL; list = list->next) {
        if (list->refcount > 0)
            return TRUE;
    }
    return FALSE;
}