apr_brigade.c

一套很值得分析的短信SMS开发源代码。是我今年早些时候从taobao上买来的。但我现在也没看完（先说清楚

            return rv;
        vec->iov_len = iov_len; /* set indirectly in case size differs */
        ++vec;
    }

    *nvec = vec - orig;
    return APR_SUCCESS;
}

APU_DECLARE(apr_status_t) apr_brigade_vputstrs(apr_bucket_brigade *b, 
                                               apr_brigade_flush flush,
                                               void *ctx,
                                               va_list va)
{
    for (;;) {
        const char *str = va_arg(va, const char *);
        apr_status_t rv;

        if (str == NULL)
            break;

        rv = apr_brigade_write(b, flush, ctx, str, strlen(str));
        if (rv != APR_SUCCESS)
            return rv;
    }

    return APR_SUCCESS;
}

APU_DECLARE(apr_status_t) apr_brigade_putc(apr_bucket_brigade *b,
                                           apr_brigade_flush flush, void *ctx,
                                           const char c)
{
    return apr_brigade_write(b, flush, ctx, &c, 1);
}

APU_DECLARE(apr_status_t) apr_brigade_write(apr_bucket_brigade *b,
                                            apr_brigade_flush flush,
                                            void *ctx, 
                                            const char *str, apr_size_t nbyte)
{
    apr_bucket *e = APR_BRIGADE_LAST(b);
    apr_size_t remaining = APR_BUCKET_BUFF_SIZE;
    char *buf = NULL;

    if (!APR_BRIGADE_EMPTY(b) && APR_BUCKET_IS_HEAP(e)) {
        apr_bucket_heap *h = e->data;

        /* HEAP bucket start offsets are always in-memory, safe to cast */
        remaining = h->alloc_len - (e->length + (apr_size_t)e->start);
        buf = h->base + e->start + e->length;
    }

    if (nbyte > remaining) {
        /* either a buffer bucket exists but is full, 
         * or no buffer bucket exists and the data is too big
         * to buffer.  In either case, we should flush.  */
        if (flush) {
            e = apr_bucket_transient_create(str, nbyte, b->bucket_alloc);
            APR_BRIGADE_INSERT_TAIL(b, e);
            return flush(b, ctx);
        }
        else {
            e = apr_bucket_heap_create(str, nbyte, NULL, b->bucket_alloc);
            APR_BRIGADE_INSERT_TAIL(b, e);
            return APR_SUCCESS;
        }
    }
    else if (!buf) {
        /* we don't have a buffer, but the data is small enough
         * that we don't mind making a new buffer */
        buf = apr_bucket_alloc(APR_BUCKET_BUFF_SIZE, b->bucket_alloc);
        e = apr_bucket_heap_create(buf, APR_BUCKET_BUFF_SIZE,
                                   apr_bucket_free, b->bucket_alloc);
        APR_BRIGADE_INSERT_TAIL(b, e);
        e->length = 0;   /* We are writing into the brigade, and
                          * allocating more memory than we need.  This
                          * ensures that the bucket thinks it is empty just
                          * after we create it.  We'll fix the length
                          * once we put data in it below.
                          */
    }

    /* there is a sufficiently big buffer bucket available now */
    memcpy(buf, str, nbyte);
    e->length += nbyte;

    return APR_SUCCESS;
}

APU_DECLARE(apr_status_t) apr_brigade_writev(apr_bucket_brigade *b,
                                             apr_brigade_flush flush,
                                             void *ctx,
                                             const struct iovec *vec,
                                             apr_size_t nvec)
{
    apr_bucket *e;
    apr_size_t total_len;
    apr_size_t i;
    char *buf;

    /* Compute the total length of the data to be written.
     */
    total_len = 0;
    for (i = 0; i < nvec; i++) {
       total_len += vec[i].iov_len;
    }

    /* If the data to be written is very large, try to convert
     * the iovec to transient buckets rather than copying.
     */
    if (total_len > APR_BUCKET_BUFF_SIZE) {
        if (flush) {
            for (i = 0; i < nvec; i++) {
                e = apr_bucket_transient_create(vec[i].iov_base,
                                                vec[i].iov_len,
                                                b->bucket_alloc);
                APR_BRIGADE_INSERT_TAIL(b, e);
            }
            return flush(b, ctx);
        }
        else {
            for (i = 0; i < nvec; i++) {
                e = apr_bucket_heap_create((const char *) vec[i].iov_base,
                                           vec[i].iov_len, NULL,
                                           b->bucket_alloc);
                APR_BRIGADE_INSERT_TAIL(b, e);
            }
            return APR_SUCCESS;
        }
    }

    i = 0;

    /* If there is a heap bucket at the end of the brigade
     * already, copy into the existing bucket.
     */
    e = APR_BRIGADE_LAST(b);
    if (!APR_BRIGADE_EMPTY(b) && APR_BUCKET_IS_HEAP(e)) {
        apr_bucket_heap *h = e->data;
        apr_size_t remaining = h->alloc_len -
            (e->length + (apr_size_t)e->start);
        buf = h->base + e->start + e->length;

        if (remaining >= total_len) {
            /* Simple case: all the data will fit in the
             * existing heap bucket
             */
            for (; i < nvec; i++) {
                apr_size_t len = vec[i].iov_len;
                memcpy(buf, (const void *) vec[i].iov_base, len);
                buf += len;
            }
            e->length += total_len;
            return APR_SUCCESS;
        }
        else {
            /* More complicated case: not all of the data
             * will fit in the existing heap bucket.  The
             * total data size is <= APR_BUCKET_BUFF_SIZE,
             * so we'll need only one additional bucket.
             */
            const char *start_buf = buf;
            for (; i < nvec; i++) {
                apr_size_t len = vec[i].iov_len;
                if (len > remaining) {
                    break;
                }
                memcpy(buf, (const void *) vec[i].iov_base, len);
                buf += len;
                remaining -= len;
            }
            e->length += (buf - start_buf);
            total_len -= (buf - start_buf);

            if (flush) {
                apr_status_t rv = flush(b, ctx);
                if (rv != APR_SUCCESS) {
                    return rv;
                }
            }

            /* Now fall through into the case below to
             * allocate another heap bucket and copy the
             * rest of the array.  (Note that i is not
             * reset to zero here; it holds the index
             * of the first vector element to be
             * written to the new bucket.)
             */
        }
    }

    /* Allocate a new heap bucket, and copy the data into it.
     * The checks above ensure that the amount of data to be
     * written here is no larger than APR_BUCKET_BUFF_SIZE.
     */
    buf = apr_bucket_alloc(APR_BUCKET_BUFF_SIZE, b->bucket_alloc);
    e = apr_bucket_heap_create(buf, APR_BUCKET_BUFF_SIZE,
                               apr_bucket_free, b->bucket_alloc);
    for (; i < nvec; i++) {
        apr_size_t len = vec[i].iov_len;
        memcpy(buf, (const void *) vec[i].iov_base, len);
        buf += len;
    }
    e->length = total_len;
    APR_BRIGADE_INSERT_TAIL(b, e);

    return APR_SUCCESS;
}

APU_DECLARE(apr_status_t) apr_brigade_puts(apr_bucket_brigade *bb,
                                           apr_brigade_flush flush, void *ctx,
                                           const char *str)
{
    apr_size_t len = strlen(str);
    apr_bucket *bkt = APR_BRIGADE_LAST(bb);
    if (!APR_BRIGADE_EMPTY(bb) && APR_BUCKET_IS_HEAP(bkt)) {
        /* If there is enough space available in a heap bucket
         * at the end of the brigade, copy the string directly
         * into the heap bucket
         */
        apr_bucket_heap *h = bkt->data;
        apr_size_t bytes_avail = h->alloc_len - bkt->length;

        if (bytes_avail >= len) {
            char *buf = h->base + bkt->start + bkt->length;
            memcpy(buf, str, len);
            bkt->length += len;
            return APR_SUCCESS;
        }
    }

    /* If the string could not be copied into an existing heap
     * bucket, delegate the work to apr_brigade_write(), which
     * knows how to grow the brigade
     */
    return apr_brigade_write(bb, flush, ctx, str, len);
}

APU_DECLARE_NONSTD(apr_status_t) apr_brigade_putstrs(apr_bucket_brigade *b, 
                                                     apr_brigade_flush flush,
                                                     void *ctx, ...)
{
    va_list va;
    apr_status_t rv;

    va_start(va, ctx);
    rv = apr_brigade_vputstrs(b, flush, ctx, va);
    va_end(va);
    return rv;
}

APU_DECLARE_NONSTD(apr_status_t) apr_brigade_printf(apr_bucket_brigade *b, 
                                                    apr_brigade_flush flush,
                                                    void *ctx, 
                                                    const char *fmt, ...)
{
    va_list ap;
    apr_status_t rv;

    va_start(ap, fmt);
    rv = apr_brigade_vprintf(b, flush, ctx, fmt, ap);
    va_end(ap);
    return rv;
}

struct brigade_vprintf_data_t {
    apr_vformatter_buff_t vbuff;

    apr_bucket_brigade *b;  /* associated brigade */
    apr_brigade_flush *flusher; /* flushing function */
    void *ctx;

    char *cbuff; /* buffer to flush from */
};

static apr_status_t brigade_flush(apr_vformatter_buff_t *buff)
{
    /* callback function passed to ap_vformatter to be
     * called when vformatter needs to buff and
     * buff.curpos > buff.endpos
     */

    /* "downcast," have really passed a brigade_vprintf_data_t* */
    struct brigade_vprintf_data_t *vd = (struct brigade_vprintf_data_t*)buff;
    apr_status_t res = APR_SUCCESS;

    res = apr_brigade_write(vd->b, *vd->flusher, vd->ctx, vd->cbuff,
                          APR_BUCKET_BUFF_SIZE);

    if(res != APR_SUCCESS) {
      return -1;
    }

    vd->vbuff.curpos = vd->cbuff;
    vd->vbuff.endpos = vd->cbuff + APR_BUCKET_BUFF_SIZE;

    return res;
}

APU_DECLARE(apr_status_t) apr_brigade_vprintf(apr_bucket_brigade *b,
                                              apr_brigade_flush flush,
                                              void *ctx,
                                              const char *fmt, va_list va)
{
    /* the cast, in order of appearance */
    struct brigade_vprintf_data_t vd;
    char buf[APR_BUCKET_BUFF_SIZE];
    apr_size_t written;

    vd.vbuff.curpos = buf;
    vd.vbuff.endpos = buf + APR_BUCKET_BUFF_SIZE;
    vd.b = b;
    vd.flusher = &flush;
    vd.ctx = ctx;
    vd.cbuff = buf;

    written = apr_vformatter(brigade_flush, &vd.vbuff, fmt, va);

    if (written == -1) {
      return -1;
    }

    /* tack on null terminator to remaining string */
    *(vd.vbuff.curpos) = '\0';

    /* write out what remains in the buffer */
    return apr_brigade_write(b, flush, ctx, buf, vd.vbuff.curpos - buf);
}