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/*
* librdkafka - Apache Kafka C library
*
* Copyright (c) 2018 Magnus Edenhill
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/**
* Background queue thread and event handling.
*
* See rdkafka.h's rd_kafka_conf_set_background_event_cb() for details.
*/
#include "rd.h"
#include "rdkafka_int.h"
#include "rdkafka_event.h"
#include "rdkafka_interceptor.h"
#include <signal.h>
/**
* @brief Call the registered background_event_cb.
* @locality rdkafka background queue thread
*/
static RD_INLINE void rd_kafka_call_background_event_cb(rd_kafka_t *rk,
rd_kafka_op_t *rko) {
rd_assert(!rk->rk_background.calling);
rk->rk_background.calling = 1;
rk->rk_conf.background_event_cb(rk, rko, rk->rk_conf.opaque);
rk->rk_background.calling = 0;
}
/**
* @brief Background queue handler.
*
* Triggers the background_event_cb for all event:able ops,
* for non-event:able ops:
* - call op callback if set, else
* - log and discard the op. This is a user error, forwarding non-event
* APIs to the background queue.
*/
static rd_kafka_op_res_t
rd_kafka_background_queue_serve(rd_kafka_t *rk,
rd_kafka_q_t *rkq,
rd_kafka_op_t *rko,
rd_kafka_q_cb_type_t cb_type,
void *opaque) {
rd_kafka_op_res_t res;
/*
* Dispatch Event:able ops to background_event_cb()
*/
if (likely(rk->rk_conf.background_event_cb &&
rd_kafka_event_setup(rk, rko))) {
rd_kafka_call_background_event_cb(rk, rko);
/* Event must be destroyed by application. */
return RD_KAFKA_OP_RES_HANDLED;
}
/*
* Handle non-event:able ops through the standard poll_cb that
* will trigger type-specific callbacks (and return OP_RES_HANDLED)
* or do no handling and return OP_RES_PASS.
* Also signal yield to q_serve() (which implies that op was handled).
*/
res = rd_kafka_poll_cb(rk, rkq, rko, RD_KAFKA_Q_CB_CALLBACK, opaque);
if (res == RD_KAFKA_OP_RES_HANDLED || res == RD_KAFKA_OP_RES_YIELD)
return res;
/* Op was not handled, log and destroy it. */
rd_kafka_log(rk, LOG_NOTICE, "BGQUEUE",
"No support for handling "
"non-event op %s in background queue: discarding",
rd_kafka_op2str(rko->rko_type));
rd_kafka_op_destroy(rko);
/* Indicate that the op was handled. */
return RD_KAFKA_OP_RES_HANDLED;
}
/**
* @brief Main loop for background queue thread.
*/
int rd_kafka_background_thread_main(void *arg) {
rd_kafka_t *rk = arg;
rd_kafka_set_thread_name("background");
rd_kafka_set_thread_sysname("rdk:bg");
rd_kafka_interceptors_on_thread_start(rk, RD_KAFKA_THREAD_BACKGROUND);
(void)rd_atomic32_add(&rd_kafka_thread_cnt_curr, 1);
/* Acquire lock (which was held by thread creator during creation)
* to synchronise state. */
rd_kafka_wrlock(rk);
rd_kafka_wrunlock(rk);
mtx_lock(&rk->rk_init_lock);
rk->rk_init_wait_cnt--;
cnd_broadcast(&rk->rk_init_cnd);
mtx_unlock(&rk->rk_init_lock);
while (likely(!rd_kafka_terminating(rk))) {
rd_kafka_q_serve(rk->rk_background.q, 10 * 1000, 0,
RD_KAFKA_Q_CB_RETURN,
rd_kafka_background_queue_serve, NULL);
}
/* Inform the user that they terminated the client before
* all outstanding events were handled. */
if (rd_kafka_q_len(rk->rk_background.q) > 0)
rd_kafka_log(rk, LOG_INFO, "BGQUEUE",
"Purging %d unserved events from background queue",
rd_kafka_q_len(rk->rk_background.q));
rd_kafka_q_disable(rk->rk_background.q);
rd_kafka_q_purge(rk->rk_background.q);
rd_kafka_dbg(rk, GENERIC, "BGQUEUE", "Background queue thread exiting");
rd_kafka_interceptors_on_thread_exit(rk, RD_KAFKA_THREAD_BACKGROUND);
rd_atomic32_sub(&rd_kafka_thread_cnt_curr, 1);
return 0;
}
/**
* @brief Create the background thread.
*
* @locks_acquired rk_init_lock
* @locks_required rd_kafka_wrlock()
*/
rd_kafka_resp_err_t rd_kafka_background_thread_create(rd_kafka_t *rk,
char *errstr,
size_t errstr_size) {
#ifndef _WIN32
sigset_t newset, oldset;
#endif
if (rk->rk_background.q) {
rd_snprintf(errstr, errstr_size,
"Background thread already created");
return RD_KAFKA_RESP_ERR__CONFLICT;
}
rk->rk_background.q = rd_kafka_q_new(rk);
mtx_lock(&rk->rk_init_lock);
rk->rk_init_wait_cnt++;
#ifndef _WIN32
/* Block all signals in newly created threads.
* To avoid race condition we block all signals in the calling
* thread, which the new thread will inherit its sigmask from,
* and then restore the original sigmask of the calling thread when
* we're done creating the thread. */
sigemptyset(&oldset);
sigfillset(&newset);
if (rk->rk_conf.term_sig) {
struct sigaction sa_term = {.sa_handler =
rd_kafka_term_sig_handler};
sigaction(rk->rk_conf.term_sig, &sa_term, NULL);
}
pthread_sigmask(SIG_SETMASK, &newset, &oldset);
#endif
if ((thrd_create(&rk->rk_background.thread,
rd_kafka_background_thread_main, rk)) !=
thrd_success) {
rd_snprintf(errstr, errstr_size,
"Failed to create background thread: %s",
rd_strerror(errno));
rd_kafka_q_destroy_owner(rk->rk_background.q);
rk->rk_background.q = NULL;
rk->rk_init_wait_cnt--;
mtx_unlock(&rk->rk_init_lock);
#ifndef _WIN32
/* Restore sigmask of caller */
pthread_sigmask(SIG_SETMASK, &oldset, NULL);
#endif
return RD_KAFKA_RESP_ERR__CRIT_SYS_RESOURCE;
}
mtx_unlock(&rk->rk_init_lock);
#ifndef _WIN32
/* Restore sigmask of caller */
pthread_sigmask(SIG_SETMASK, &oldset, NULL);
#endif
return RD_KAFKA_RESP_ERR_NO_ERROR;
}
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