rsyslog/threads.c

/* threads.c
 *
 * This file implements threading support helpers (and maybe the thread object)
 * for rsyslog.
 *
 * File begun on 2007-12-14 by RGerhards
 *
 * Copyright 2007-2016 Adiscon GmbH.
 *
 * This file is part of rsyslog.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *       -or-
 *       see COPYING.ASL20 in the source distribution
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#include "config.h"

#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <errno.h>
#include <pthread.h>
#include <assert.h>
#ifdef HAVE_SYS_PRCTL_H
    #include <sys/prctl.h>
#endif

#include "rsyslog.h"
#include "dirty.h"
#include "linkedlist.h"
#include "threads.h"
#include "srUtils.h"
#include "errmsg.h"
#include "glbl.h"
#include "unicode-helper.h"
#include "rsconf.h"

/* linked list of currently-known threads */
static linkedList_t llThrds;

/* methods */

/* Construct a new thread object
 */
static rsRetVal thrdConstruct(thrdInfo_t **ppThis) {
    DEFiRet;
    thrdInfo_t *pThis;

    assert(ppThis != NULL);

    CHKmalloc(pThis = calloc(1, sizeof(thrdInfo_t)));
    pthread_mutex_init(&pThis->mutThrd, NULL);
    pthread_cond_init(&pThis->condThrdTerm, NULL);
    *ppThis = pThis;

finalize_it:
    RETiRet;
}


/* Destructs a thread object. The object must not be linked to the
 * linked list of threads. Please note that the thread should have been
 * stopped before. If not, we try to do it.
 */
static rsRetVal thrdDestruct(thrdInfo_t *pThis) {
    DEFiRet;
    assert(pThis != NULL);

    pthread_mutex_lock(&pThis->mutThrd);
    if (pThis->bIsActive == 1) {
        pthread_mutex_unlock(&pThis->mutThrd);
        thrdTerminate(pThis);
    } else {
        pthread_mutex_unlock(&pThis->mutThrd);
        pthread_join(pThis->thrdID, NULL);
    }

    /* call cleanup function, if any */
    if (pThis->pAfterRun != NULL) pThis->pAfterRun(pThis);

    pthread_mutex_destroy(&pThis->mutThrd);
    pthread_cond_destroy(&pThis->condThrdTerm);
    free(pThis->name);
    free(pThis);

    RETiRet;
}


/* terminate a thread via the non-cancel interface
 * This is a separate function as it involves a bit more of code.
 * rgerhads, 2009-10-15
 */
static rsRetVal thrdTerminateNonCancel(thrdInfo_t *pThis) {
    struct timespec tTimeout;
    int ret;
    int was_active;
    DEFiRet;
    assert(pThis != NULL);

    DBGPRINTF("request term via SIGTTIN for input thread '%s' %p\n", pThis->name, (void *)pThis->thrdID);

    pThis->bShallStop = RSTRUE;
    d_pthread_mutex_lock(&pThis->mutThrd);
    timeoutComp(&tTimeout, runConf->globals.inputTimeoutShutdown);
    was_active = pThis->bIsActive;
    while (was_active) {
        if (dbgTimeoutToStderr) {
            fprintf(stderr,
                    "rsyslogd debug: info: trying to cooperatively stop "
                    "input %s, timeout %d ms\n",
                    pThis->name, runConf->globals.inputTimeoutShutdown);
        }
        DBGPRINTF("thread %s: initiating termination, timeout %d ms\n", pThis->name,
                  runConf->globals.inputTimeoutShutdown);
        const int r = pthread_kill(pThis->thrdID, SIGTTIN);
        if (r != 0) {
            LogError(r, RS_RET_INTERNAL_ERROR,
                     "error terminating thread %s "
                     "this may cause shutdown issues",
                     pThis->name);
        }
        ret = d_pthread_cond_timedwait(&pThis->condThrdTerm, &pThis->mutThrd, &tTimeout);
        if (ret == ETIMEDOUT) {
            DBGPRINTF(
                "input thread term: timeout expired waiting on thread %s "
                "termination - canceling\n",
                pThis->name);
            if (dbgTimeoutToStderr) {
                fprintf(stderr,
                        "rsyslogd debug: input thread term: "
                        "timeout expired waiting on thread %s "
                        "termination - canceling\n",
                        pThis->name);
            }
            pthread_cancel(pThis->thrdID);
            break;
        } else if (ret != 0) {
            char errStr[1024];
            int err = ret;
            rs_strerror_r(err, errStr, sizeof(errStr));
            DBGPRINTF("input thread term: cond_wait returned with error %d: %s\n", err, errStr);
        }
        was_active = pThis->bIsActive;
    }
    d_pthread_mutex_unlock(&pThis->mutThrd);

    if (was_active) {
        DBGPRINTF("non-cancel input thread termination FAILED for thread %s %p\n", pThis->name, (void *)pThis->thrdID);
    } else {
        DBGPRINTF("non-cancel input thread termination succeeded for thread %s %p\n", pThis->name,
                  (void *)pThis->thrdID);
    }

    RETiRet;
}


/* terminate a thread gracefully.
 */
rsRetVal thrdTerminate(thrdInfo_t *pThis) {
    DEFiRet;
    assert(pThis != NULL);

    if (pThis->bNeedsCancel) {
        DBGPRINTF("request term via canceling for input thread %s\n", pThis->name);
        if (dbgTimeoutToStderr) {
            fprintf(stderr,
                    "rsyslogd debug: request term via canceling for "
                    "input thread %s\n",
                    pThis->name);
        }
        pthread_cancel(pThis->thrdID);
    } else {
        thrdTerminateNonCancel(pThis);
    }
    pthread_join(pThis->thrdID, NULL); /* wait for input thread to complete */

    RETiRet;
}


/* terminate all known threads gracefully.
 */
rsRetVal thrdTerminateAll(void) {
    DEFiRet;
    llDestroy(&llThrds);
    RETiRet;
}


/* This is an internal wrapper around the user thread function. Its
 * purpose is to handle all the necessary housekeeping stuff so that the
 * user function needs not to be aware of the threading calls. The user
 * function call has just "normal", non-threading semantics.
 * rgerhards, 2007-12-17
 */
static ATTR_NORETURN void *thrdStarter(void *const arg) {
    DEFiRet;
    thrdInfo_t *const pThis = (thrdInfo_t *)arg;
#if defined(HAVE_PRCTL) && defined(PR_SET_NAME)
    uchar thrdName[32] = "in:";
#endif

    assert(pThis != NULL);
    assert(pThis->pUsrThrdMain != NULL);

#if defined(HAVE_PRCTL) && defined(PR_SET_NAME)
    ustrncpy(thrdName + 3, pThis->name, 20);
    dbgOutputTID((char *)thrdName);

    /* set thread name - we ignore if the call fails, has no harsh consequences... */
    if (prctl(PR_SET_NAME, thrdName, 0, 0, 0) != 0) {
        DBGPRINTF("prctl failed, not setting thread name for '%s'\n", pThis->name);
    } else {
        DBGPRINTF("set thread name to '%s'\n", thrdName);
    }
#endif

    /* block all signals except SIGTTIN and SIGSEGV */
    sigset_t sigSet;
    sigfillset(&sigSet);
    sigdelset(&sigSet, SIGTTIN);
    sigdelset(&sigSet, SIGSEGV);
    pthread_sigmask(SIG_BLOCK, &sigSet, NULL);

    /* setup complete, we are now ready to execute the user code. We will not
     * regain control until the user code is finished, in which case we terminate
     * the thread.
     */
    iRet = pThis->pUsrThrdMain(pThis);

    if (iRet == RS_RET_OK) {
        dbgprintf("thrdStarter: usrThrdMain %s - 0x%lx returned with iRet %d, exiting now.\n", pThis->name,
                  (unsigned long)pThis->thrdID, iRet);
    } else {
        LogError(0, iRet, "main thread of %s terminated abnormally", pThis->name);
    }

    /* signal master control that we exit (we do the mutex lock mostly to
     * keep the thread debugger happer, it would not really be necessary with
     * the logic we employ...)
     */
    d_pthread_mutex_lock(&pThis->mutThrd);
    pThis->bIsActive = 0;
    pthread_cond_signal(&pThis->condThrdTerm);
    d_pthread_mutex_unlock(&pThis->mutThrd);

    pthread_exit(0);
}
/* Start a new thread and add it to the list of currently
 * executing threads. It is added at the end of the list.
 * rgerhards, 2007-12-14
 */
rsRetVal thrdCreate(rsRetVal (*thrdMain)(thrdInfo_t *),
                    rsRetVal (*afterRun)(thrdInfo_t *),
                    sbool bNeedsCancel,
                    uchar *name) {
    DEFiRet;
    thrdInfo_t *pThis;
#if defined(_AIX)
    pthread_attr_t aix_attr;
#endif

    assert(thrdMain != NULL);

    CHKiRet(thrdConstruct(&pThis));
    pThis->bIsActive = 1;
    pThis->pUsrThrdMain = thrdMain;
    pThis->pAfterRun = afterRun;
    pThis->bNeedsCancel = bNeedsCancel;
    pThis->name = ustrdup(name);
#if defined(_AIX)
    pthread_attr_init(&aix_attr);
    pthread_attr_setstacksize(&aix_attr, 4096 * 512);
    pthread_create(&pThis->thrdID, &aix_attr, thrdStarter, pThis);
#else
    pthread_create(&pThis->thrdID, &default_thread_attr, thrdStarter, pThis);
#endif
    CHKiRet(llAppend(&llThrds, NULL, pThis));

finalize_it:
    RETiRet;
}


/* initialize the thread-support subsystem
 * must be called once at the start of the program
 */
rsRetVal thrdInit(void) {
    DEFiRet;
    iRet = llInit(&llThrds, (rsRetVal(*)(void *))thrdDestruct, NULL, NULL);
    RETiRet;
}


/* de-initialize the thread subsystem
 * must be called once at the end of the program
 */
rsRetVal thrdExit(void) {
    DEFiRet;
    iRet = llDestroy(&llThrds);
    RETiRet;
}


/* vi:set ai:
 */