Commit c7486525 authored by Greg Stein's avatar Greg Stein
Browse files

Add a comment about an assumption we make in our keepalive buffering. 

Delay the check for "too many items in an iovec" until we actually try to
put something in there. This allows that N+1 bucket to be an EOS, FLUSH,
FILE, or zero-length bucket without triggering a split. Only if that next
bucket has iovec data will a split be made.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@88969 13f79535-47bb-0310-9956-ffa450edef68
parent b17ce220

server/core.c

+23 −10
Original line number Diff line number Diff line
@@ -3092,29 +3092,31 @@ static apr_status_t core_output_filter(ap_filter_t *f, apr_bucket_brigade *b) 


                rv = apr_bucket_read(e, &str, &n, APR_BLOCK_READ);

                if (n) {

                    nbytes += n;

                    if (!fd) {

                        if (nvec == MAX_IOVEC_TO_WRITE) {

                            /* woah! too many. stop now. */

                            more = apr_brigade_split(b, e);

                            break;

                        }

                        vec[nvec].iov_base = (char*) str;

                        vec[nvec].iov_len = n;

                        nvec++;

                    }

                    else {

                        /* The bucket is a trailer to a file bucket */



                        if (nvec_trailers == MAX_IOVEC_TO_WRITE) {

                            /* woah! too many. stop now. */

                            more = apr_brigade_split(b, e);

                            break;

                        }

                        vec_trailers[nvec_trailers].iov_base = (char*) str;

                        vec_trailers[nvec_trailers].iov_len = n;

                        nvec_trailers++;

                    }

                    nbytes += n;

                }

            }

    

            if ((nvec == MAX_IOVEC_TO_WRITE) || 

                (nvec_trailers == MAX_IOVEC_TO_WRITE)) {

                /* Split the brigade and break */

                if (APR_BUCKET_NEXT(e) != APR_BRIGADE_SENTINEL(b)) {

                    more = apr_brigade_split(b, APR_BUCKET_NEXT(e));

                }

                break;

            }

        }

    

        /* Completed iterating over the brigades, now determine if we want
@@ -3153,6 +3155,17 @@ static apr_status_t core_output_filter(ap_filter_t *f, apr_bucket_brigade *b) 
                    apr_size_t n;



                    rv = apr_bucket_read(bucket, &str, &n, APR_BLOCK_READ);



                    /* This apr_brigade_write does not use a flush function

                       because we assume that we will not write enough data

                       into it to cause a flush. However, if we *do* write

                       "too much", then we could end up with transient

                       buckets which would suck. This works for now, but is

                       a bit shaky if changes are made to some of the

                       buffering sizes. Let's do an assert to prevent

                       potential future problems... */

                    AP_DEBUG_ASSERT(AP_MIN_BYTES_TO_WRITE <

                                    APR_BUCKET_BUFF_SIZE);

                    apr_brigade_write(ctx->b, NULL, NULL, str, n);

                }

                apr_brigade_destroy(b);