/*
* Increment local session id
*/
void pool_incremnet_local_session_id(void)
{
POOL_PROCESS_CONTEXT *p = pool_get_process_context();
if (!p)
ereport(ERROR,
(errmsg("failed to get process context")));
p->local_session_id++;
}
/*
* initialize connection pools. this should be called once at the startup.
*/
int pool_init_cp(void)
{
int i;
pool_connection_pool = (POOL_CONNECTION_POOL *)malloc(sizeof(POOL_CONNECTION_POOL)*pool_config->max_pool);
if (pool_connection_pool == NULL)
{
pool_error("pool_init_cp: malloc() failed");
return -1;
}
memset(pool_connection_pool, 0, sizeof(POOL_CONNECTION_POOL)*pool_config->max_pool);
for (i = 0; i < pool_config->max_pool; i++)
{
pool_connection_pool[i].info = pool_coninfo(pool_get_process_context()->proc_id, i, 0);
memset(pool_connection_pool[i].info, 0, sizeof(ConnectionInfo) * MAX_NUM_BACKENDS);
}
return 0;
}
/*
* Initialize per session context
*/
void pool_init_session_context(POOL_CONNECTION *frontend, POOL_CONNECTION_POOL *backend)
{
session_context = &session_context_d;
/* Get Process context */
session_context->process_context = pool_get_process_context();
if (!session_context->process_context)
{
pool_error("pool_init_session_context: cannot get process context");
return;
}
/* Set connection info */
session_context->frontend = frontend;
session_context->backend = backend;
/* Initialize query context */
session_context->query_context = NULL;
/* Initialize local session id */
pool_incremnet_local_session_id();
/* Initialize sent message list */
init_sent_message_list();
/* Create memory context */
session_context->memory_context = pool_memory_create(PREPARE_BLOCK_SIZE);
/* Choose load balancing node if necessary */
if (pool_config->load_balance_mode)
{
ProcessInfo *process_info = pool_get_my_process_info();
if (!process_info)
{
pool_error("pool_init_session_context: pool_get_my_process_info failed");
return;
}
session_context->load_balance_node_id =
process_info->connection_info->load_balancing_node =
select_load_balancing_node();
pool_debug("selected load balancing node: %d", backend->info->load_balancing_node);
}
/* Unset query is in progress */
pool_unset_query_in_progress();
/* The command in progress has not succeeded yet */
pool_unset_command_success();
/* We don't have a write query in this transaction yet */
pool_unset_writing_transaction();
/* Error doesn't occur in this transaction yet */
pool_unset_failed_transaction();
/* Forget transaction isolation mode */
pool_unset_transaction_isolation();
/* We don't skip reading from backends */
pool_unset_skip_reading_from_backends();
/* Backends have not ignored messages yet */
pool_unset_ignore_till_sync();
/* Initialize where to send map for PREPARE statements */
#ifdef NOT_USED
memset(&session_context->prep_where, 0, sizeof(session_context->prep_where));
session_context->prep_where.nelem = POOL_MAX_PREPARED_STATEMENTS;
#endif /* NOT_USED */
/* Reset flag to indicate difference in number of affected tuples
* in UPDATE/DELETE.
*/
session_context->mismatch_ntuples = false;
if (pool_config->memory_cache_enabled)
{
session_context->query_cache_array = pool_create_query_cache_array();
session_context->num_selects = 0;
}
}
/*
* child main loop
*/
void do_child(int unix_fd, int inet_fd)
{
POOL_CONNECTION *frontend;
POOL_CONNECTION_POOL *backend;
struct timeval now;
struct timezone tz;
struct timeval timeout;
static int connected; /* non 0 if has been accepted connections from frontend */
int connections_count = 0; /* used if child_max_connections > 0 */
int found;
char psbuf[NI_MAXHOST + 128];
pool_debug("I am %d", getpid());
/* Identify myself via ps */
init_ps_display("", "", "", "");
/* set up signal handlers */
signal(SIGALRM, SIG_DFL);
signal(SIGTERM, die);
signal(SIGINT, die);
signal(SIGHUP, reload_config_handler);
signal(SIGQUIT, die);
signal(SIGCHLD, SIG_DFL);
signal(SIGUSR1, close_idle_connection);
signal(SIGUSR2, wakeup_handler);
signal(SIGPIPE, SIG_IGN);
#ifdef NONE_BLOCK
/* set listen fds to none-blocking */
pool_set_nonblock(unix_fd);
if (inet_fd)
{
pool_set_nonblock(inet_fd);
}
#endif
/* Initialize my backend status */
pool_initialize_private_backend_status();
/* Initialize per process context */
pool_init_process_context();
/* initialize random seed */
gettimeofday(&now, &tz);
#if defined(sun) || defined(__sun)
srand((unsigned int) now.tv_usec);
#else
srandom((unsigned int) now.tv_usec);
#endif
/* initialize system db connection */
init_system_db_connection();
/* initialize connection pool */
if (pool_init_cp())
{
child_exit(1);
}
/*
* Open pool_passwd in child process. This is necessary to avoid the
* file descriptor race condition reported in [pgpool-general: 1141].
*/
if (strcmp("", pool_config->pool_passwd))
{
pool_reopen_passwd_file();
}
timeout.tv_sec = pool_config->child_life_time;
timeout.tv_usec = 0;
for (;;)
{
StartupPacket *sp;
idle = 1;
/* pgpool stop request already sent? */
check_stop_request();
/* Check if restart request is set because of failback event
* happend. If so, exit myself with exit code 1 to be
* restarted by pgpool parent.
*/
if (pool_get_my_process_info()->need_to_restart)
{
pool_log("do_child: failback event found. restart myself.");
pool_get_my_process_info()->need_to_restart = 0;
child_exit(1);
}
accepted = 0;
/* perform accept() */
frontend = do_accept(unix_fd, inet_fd, &timeout);
if (frontend == NULL) /* connection request from frontend timed out */
{
/* check select() timeout */
if (connected && pool_config->child_life_time > 0 &&
timeout.tv_sec == 0 && timeout.tv_usec == 0)
{
pool_debug("child life %d seconds expired", pool_config->child_life_time);
/*
* Doesn't need to call this. child_exit() calls it.
* send_frontend_exits();
*/
child_exit(2);
}
continue;
}
/* set frontend fd to blocking */
pool_unset_nonblock(frontend->fd);
/* reset busy flag */
idle = 0;
/* check backend timer is expired */
if (backend_timer_expired)
{
pool_backend_timer();
backend_timer_expired = 0;
}
/* read the startup packet */
retry_startup:
sp = read_startup_packet(frontend);
if (sp == NULL)
{
/* failed to read the startup packet. return to the accept() loop */
pool_close(frontend);
connection_count_down();
continue;
}
/* cancel request? */
if (sp->major == 1234 && sp->minor == 5678)
{
cancel_request((CancelPacket *)sp->startup_packet);
pool_close(frontend);
pool_free_startup_packet(sp);
connection_count_down();
continue;
}
/* SSL? */
if (sp->major == 1234 && sp->minor == 5679 && !frontend->ssl_active)
{
pool_debug("SSLRequest from client");
pool_ssl_negotiate_serverclient(frontend);
goto retry_startup;
}
if (pool_config->enable_pool_hba)
{
/*
* do client authentication.
* Note that ClientAuthentication does not return if frontend
* was rejected; it simply terminates this process.
*/
frontend->protoVersion = sp->major;
frontend->database = strdup(sp->database);
if (frontend->database == NULL)
{
pool_error("do_child: strdup failed: %s\n", strerror(errno));
child_exit(1);
}
frontend->username = strdup(sp->user);
if (frontend->username == NULL)
{
pool_error("do_child: strdup failed: %s\n", strerror(errno));
child_exit(1);
}
ClientAuthentication(frontend);
}
/*
* Ok, negotiation with frontend has been done. Let's go to the
* next step. Connect to backend if there's no existing
* connection which can be reused by this frontend.
* Authentication is also done in this step.
*/
/* Check if restart request is set because of failback event
* happend. If so, close idle connections to backend and make
* a new copy of backend status.
*/
if (pool_get_my_process_info()->need_to_restart)
{
pool_log("do_child: failback event found. discard existing connections");
pool_get_my_process_info()->need_to_restart = 0;
close_idle_connection(0);
pool_initialize_private_backend_status();
}
/*
* if there's no connection associated with user and database,
* we need to connect to the backend and send the startup packet.
*/
/* look for existing connection */
found = 0;
backend = pool_get_cp(sp->user, sp->database, sp->major, 1);
if (backend != NULL)
{
found = 1;
/* existing connection associated with same user/database/major found.
* however we should make sure that the startup packet contents are identical.
* OPTION data and others might be different.
*/
if (sp->len != MASTER_CONNECTION(backend)->sp->len)
{
pool_debug("do_child: connection exists but startup packet length is not identical");
found = 0;
}
else if(memcmp(sp->startup_packet, MASTER_CONNECTION(backend)->sp->startup_packet, sp->len) != 0)
{
pool_debug("do_child: connection exists but startup packet contents is not identical");
found = 0;
}
if (found == 0)
{
/* we need to discard existing connection since startup packet is different */
pool_discard_cp(sp->user, sp->database, sp->major);
backend = NULL;
}
}
if (backend == NULL)
{
/* create a new connection to backend */
if ((backend = connect_backend(sp, frontend)) == NULL)
{
connection_count_down();
continue;
}
}
else
{
/* reuse existing connection */
if (!connect_using_existing_connection(frontend, backend, sp))
continue;
}
connected = 1;
/* show ps status */
sp = MASTER_CONNECTION(backend)->sp;
snprintf(psbuf, sizeof(psbuf), "%s %s %s idle",
sp->user, sp->database, remote_ps_data);
set_ps_display(psbuf, false);
/*
* Initialize per session context
*/
pool_init_session_context(frontend, backend);
/* Mark this connection pool is connected from frontend */
pool_coninfo_set_frontend_connected(pool_get_process_context()->proc_id, pool_pool_index());
/* query process loop */
for (;;)
{
POOL_STATUS status;
status = pool_process_query(frontend, backend, 0);
sp = MASTER_CONNECTION(backend)->sp;
switch (status)
{
/* client exits */
case POOL_END:
/*
* do not cache connection if:
* pool_config->connection_cahe == 0 or
* database name is template0, template1, postgres or regression
*/
if (pool_config->connection_cache == 0 ||
!strcmp(sp->database, "template0") ||
!strcmp(sp->database, "template1") ||
!strcmp(sp->database, "postgres") ||
!strcmp(sp->database, "regression"))
{
reset_connection();
pool_close(frontend);
pool_send_frontend_exits(backend);
pool_discard_cp(sp->user, sp->database, sp->major);
}
else
{
POOL_STATUS status1;
/* send reset request to backend */
status1 = pool_process_query(frontend, backend, 1);
pool_close(frontend);
/* if we detect errors on resetting connection, we need to discard
* this connection since it might be in unknown status
*/
if (status1 != POOL_CONTINUE)
{
pool_debug("error in resetting connections. discarding connection pools...");
pool_send_frontend_exits(backend);
pool_discard_cp(sp->user, sp->database, sp->major);
}
else
pool_connection_pool_timer(backend);
}
break;
/* error occurred. discard backend connection pool
and disconnect connection to the frontend */
case POOL_ERROR:
pool_log("do_child: exits with status 1 due to error");
child_exit(1);
break;
/* fatal error occurred. just exit myself... */
case POOL_FATAL:
notice_backend_error(1);
child_exit(1);
break;
/* not implemented yet */
case POOL_IDLE:
do_accept(unix_fd, inet_fd, &timeout);
pool_debug("accept while idle");
break;
default:
break;
}
if (status != POOL_CONTINUE)
break;
}
/* Destroy session context */
pool_session_context_destroy();
/* Mark this connection pool is not connected from frontend */
pool_coninfo_unset_frontend_connected(pool_get_process_context()->proc_id, pool_pool_index());
accepted = 0;
connection_count_down();
timeout.tv_sec = pool_config->child_life_time;
timeout.tv_usec = 0;
/* increment queries counter if necessary */
if ( pool_config->child_max_connections > 0 )
connections_count++;
/* check if maximum connections count for this child reached */
if ( ( pool_config->child_max_connections > 0 ) &&
( connections_count >= pool_config->child_max_connections ) )
{
pool_log("child exiting, %d connections reached", pool_config->child_max_connections);
send_frontend_exits();
child_exit(2);
}
}
child_exit(0);
}