Redis Bio

概要
Redis BioはBackground I/Oサービスfor Redisです.彼はそれらの時間のかかるio操作をバックグラウンドのスレッドに置いて実行した.プライマリ・スレッドはサービスに集中します.時間のかかる解放、書き込み操作などによるサービスの待機を避ける.実現も特に簡単です.新しい処理スレッドを使用します.臨界領域を使用してタスクを投入する方法で操作を完了します.
コアのいくつかの定義と方法

static pthread_t bio_threads[BIO_NUM_OPS]; //  pthread
static pthread_mutex_t bio_mutex[BIO_NUM_OPS];//  mutex
static pthread_cond_t bio_newjob_cond[BIO_NUM_OPS];//         
static pthread_cond_t bio_step_cond[BIO_NUM_OPS];//  step    
static list *bio_jobs[BIO_NUM_OPS];//  joblist

static unsigned long long bio_pending[BIO_NUM_OPS];//  pening  

struct bio_job {
    time_t time; /* Time at which the job was created. */ //    
    /* Job specific arguments pointers. If we need to pass more than three
     * arguments we can just pass a pointer to a structure or alike. */
    void *arg1, *arg2, *arg3;//       
};

bioの初期化

/* Initialize the background system, spawning the thread. */
void bioInit(void) {
    pthread_attr_t attr;
    pthread_t thread;
    size_t stacksize;
    int j;

    /* Initialization of state vars and objects */
    for (j = 0; j < BIO_NUM_OPS; j++) {//        
        pthread_mutex_init(&bio_mutex[j],NULL);
        pthread_cond_init(&bio_newjob_cond[j],NULL);
        pthread_cond_init(&bio_step_cond[j],NULL);
        bio_jobs[j] = listCreate();//       
        bio_pending[j] = 0;//     0
    }

    /* Set the stack size as by default it may be small in some system */
    pthread_attr_init(&attr);
    pthread_attr_getstacksize(&attr,&stacksize);
    if (!stacksize) stacksize = 1; /* The world is full of Solaris Fixes */
    while (stacksize < REDIS_THREAD_STACK_SIZE) stacksize *= 2;
    pthread_attr_setstacksize(&attr, stacksize);//stack size

    /* Ready to spawn our threads. We use the single argument the thread
     * function accepts in order to pass the job ID the thread is
     * responsible of. */
    for (j = 0; j < BIO_NUM_OPS; j++) {
        void *arg = (void*)(unsigned long) j;
        if (pthread_create(&thread,&attr,bioProcessBackgroundJobs,arg) != 0) {//    
            serverLog(LL_WARNING,"Fatal: Can't initialize Background Jobs.");
            exit(1);
        }
        bio_threads[j] = thread;
    }
}

作成プロセス全体は標準的な初期化プロセスです.特別なところはありません.
スレッド関数

void *bioProcessBackgroundJobs(void *arg) {//    
    struct bio_job *job;
    unsigned long type = (unsigned long) arg;
    sigset_t sigset;

    /* Check that the type is within the right interval. */
    if (type >= BIO_NUM_OPS) {//type   
        serverLog(LL_WARNING,
            "Warning: bio thread started with wrong type %lu",type);
        return NULL;
    }

    /* Make the thread killable at any time, so that bioKillThreads()
     * can work reliably. */
    pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);//    cancel
    pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);//      

    pthread_mutex_lock(&bio_mutex[type]);//    
    /* Block SIGALRM so we are sure that only the main thread will
     * receive the watchdog signal. */
    sigemptyset(&sigset);
    sigaddset(&sigset, SIGALRM);
    if (pthread_sigmask(SIG_BLOCK, &sigset, NULL))//        SIGALRM
        serverLog(LL_WARNING,
            "Warning: can't mask SIGALRM in bio.c thread: %s", strerror(errno));

    while(1) {
        listNode *ln;

        /* The loop always starts with the lock hold. */
        if (listLength(bio_jobs[type]) == 0) {
            pthread_cond_wait(&bio_newjob_cond[type],&bio_mutex[type]);//  mutex         
            continue;//      
        }
        /* Pop the job from the queue. */
        ln = listFirst(bio_jobs[type]);//       
        job = ln->value;
        /* It is now possible to unlock the background system as we know have
         * a stand alone job structure to process.*/
        pthread_mutex_unlock(&bio_mutex[type]);//           

        /* Process the job accordingly to its type. */
        if (type == BIO_CLOSE_FILE) {//       
            close((long)job->arg1);
        } else if (type == BIO_AOF_FSYNC) {
            aof_fsync((long)job->arg1);
        } else if (type == BIO_LAZY_FREE) {
            /* What we free changes depending on what arguments are set:
             * arg1 -> free the object at pointer.
             * arg2 & arg3 -> free two dictionaries (a Redis DB).
             * only arg3 -> free the skiplist. */
            if (job->arg1)
                lazyfreeFreeObjectFromBioThread(job->arg1);
            else if (job->arg2 && job->arg3)
                lazyfreeFreeDatabaseFromBioThread(job->arg2,job->arg3);
            else if (job->arg3)
                lazyfreeFreeSlotsMapFromBioThread(job->arg3);
        } else {
            serverPanic("Wrong job type in bioProcessBackgroundJobs().");
        }
        zfree(job);

        /* Unblock threads blocked on bioWaitStepOfType() if any. */
        pthread_cond_broadcast(&bio_step_cond[type]);//      setp_cond

        /* Lock again before reiterating the loop, if there are no longer
         * jobs to process we'll block again in pthread_cond_wait(). */
        pthread_mutex_lock(&bio_mutex[type]);//  
        listDelNode(bio_jobs[type],ln);//       
        bio_pending[type]--;//pending --
    }
}

整理プロセス:1ロックを取得し、タスクが存在するかどうかを判断し、存在しない場合はcond_に入るwaitは、存在する場合に1つのタスクを抽出し、タスクタイプに基づいて操作します.2.実行終了後にすべてのstep_を起動cond、再度ロックを取得します.完了したタスクを削除します.ループに入る
タスクの作成

void bioCreateBackgroundJob(int type, void *arg1, void *arg2, void *arg3) {//  job
    struct bio_job *job = zmalloc(sizeof(*job));//    
    job->time = time(NULL);//    
    job->arg1 = arg1;//    
    job->arg2 = arg2;
    job->arg3 = arg3;
    pthread_mutex_lock(&bio_mutex[type]);//   
    listAddNodeTail(bio_jobs[type],job);//    
    bio_pending[type]++;//pending++
    pthread_cond_signal(&bio_newjob_cond[type]);//    
    pthread_mutex_unlock(&bio_mutex[type]);
}

バックグラウンドioスレッドを閉じる

void bioKillThreads(void) {
    int err, j;

    for (j = 0; j < BIO_NUM_OPS; j++) {
        if (pthread_cancel(bio_threads[j]) == 0) {//  cancle
            if ((err = pthread_join(bio_threads[j],NULL)) != 0) {//join  
                serverLog(LL_WARNING,
                    "Bio thread for job type #%d can be joined: %s",
                        j, strerror(err));
            } else {
                serverLog(LL_WARNING,
                    "Bio thread for job type #%d terminated",j);
            }
        }
    }
}

いくつかのステータスの取得

unsigned long long bioWaitStepOfType(int type) {
    unsigned long long val;
    pthread_mutex_lock(&bio_mutex[type]);//  
    val = bio_pending[type];
    if (val != 0) {//
        pthread_cond_wait(&bio_step_cond[type],&bio_mutex[type]);//d    
        val = bio_pending[type];
    }
    pthread_mutex_unlock(&bio_mutex[type]);//   
    return val;
}
unsigned long long bioPendingJobsOfType(int type) {
    unsigned long long val;
    pthread_mutex_lock(&bio_mutex[type]);
    val = bio_pending[type];
    pthread_mutex_unlock(&bio_mutex[type]);
    return val;
}