apr_status_t ap_core_output_filter(ap_filter_t *f, apr_bucket_brigade *new_bb)
{
conn_rec *c = f->c;
core_net_rec *net = f->ctx;
core_output_filter_ctx_t *ctx = net->out_ctx;
apr_bucket_brigade *bb = NULL;
apr_bucket *bucket, *next, *flush_upto = NULL;
apr_size_t bytes_in_brigade, non_file_bytes_in_brigade;
int eor_buckets_in_brigade, morphing_bucket_in_brigade;
apr_status_t rv;
int loglevel = ap_get_conn_module_loglevel(c, APLOG_MODULE_INDEX);
/* Fail quickly if the connection has already been aborted. */
if (c->aborted) {
if (new_bb != NULL) {
apr_brigade_cleanup(new_bb);
}
return APR_ECONNABORTED;
}
if (ctx == NULL) {
ctx = apr_pcalloc(c->pool, sizeof(*ctx));
net->out_ctx = (core_output_filter_ctx_t *)ctx;
/*
* Need to create tmp brigade with correct lifetime. Passing
* NULL to apr_brigade_split_ex would result in a brigade
* allocated from bb->pool which might be wrong.
*/
ctx->tmp_flush_bb = apr_brigade_create(c->pool, c->bucket_alloc);
/* same for buffered_bb and ap_save_brigade */
ctx->buffered_bb = apr_brigade_create(c->pool, c->bucket_alloc);
}
if (new_bb != NULL)
bb = new_bb;
if ((ctx->buffered_bb != NULL) &&
!APR_BRIGADE_EMPTY(ctx->buffered_bb)) {
if (new_bb != NULL) {
APR_BRIGADE_PREPEND(bb, ctx->buffered_bb);
}
else {
bb = ctx->buffered_bb;
}
c->data_in_output_filters = 0;
}
else if (new_bb == NULL) {
return APR_SUCCESS;
}
/* Scan through the brigade and decide whether to attempt a write,
* and how much to write, based on the following rules:
*
* 1) The new_bb is null: Do a nonblocking write of as much as
* possible: do a nonblocking write of as much data as possible,
* then save the rest in ctx->buffered_bb. (If new_bb == NULL,
* it probably means that the MPM is doing asynchronous write
* completion and has just determined that this connection
* is writable.)
*
* 2) Determine if and up to which bucket we need to do a blocking
* write:
*
* a) The brigade contains a flush bucket: Do a blocking write
* of everything up that point.
*
* b) The request is in CONN_STATE_HANDLER state, and the brigade
* contains at least THRESHOLD_MAX_BUFFER bytes in non-file
* buckets: Do blocking writes until the amount of data in the
* buffer is less than THRESHOLD_MAX_BUFFER. (The point of this
* rule is to provide flow control, in case a handler is
* streaming out lots of data faster than the data can be
* sent to the client.)
*
* c) The request is in CONN_STATE_HANDLER state, and the brigade
* contains at least MAX_REQUESTS_IN_PIPELINE EOR buckets:
* Do blocking writes until less than MAX_REQUESTS_IN_PIPELINE EOR
* buckets are left. (The point of this rule is to prevent too many
* FDs being kept open by pipelined requests, possibly allowing a
* DoS).
*
* d) The brigade contains a morphing bucket: If there was no other
* reason to do a blocking write yet, try reading the bucket. If its
* contents fit into memory before THRESHOLD_MAX_BUFFER is reached,
* everything is fine. Otherwise we need to do a blocking write the
* up to and including the morphing bucket, because ap_save_brigade()
* would read the whole bucket into memory later on.
*
* 3) Actually do the blocking write up to the last bucket determined
* by rules 2a-d. The point of doing only one flush is to make as
* few calls to writev() as possible.
*
* 4) If the brigade contains at least THRESHOLD_MIN_WRITE
* bytes: Do a nonblocking write of as much data as possible,
* then save the rest in ctx->buffered_bb.
*/
if (new_bb == NULL) {
rv = send_brigade_nonblocking(net->client_socket, bb,
&(ctx->bytes_written), c);
if (rv != APR_SUCCESS && !APR_STATUS_IS_EAGAIN(rv)) {
/* The client has aborted the connection */
ap_log_cerror(APLOG_MARK, APLOG_TRACE1, rv, c,
"core_output_filter: writing data to the network");
apr_brigade_cleanup(bb);
c->aborted = 1;
return rv;
}
setaside_remaining_output(f, ctx, bb, c);
return APR_SUCCESS;
}
bytes_in_brigade = 0;
non_file_bytes_in_brigade = 0;
eor_buckets_in_brigade = 0;
morphing_bucket_in_brigade = 0;
for (bucket = APR_BRIGADE_FIRST(bb); bucket != APR_BRIGADE_SENTINEL(bb);
bucket = next) {
next = APR_BUCKET_NEXT(bucket);
if (!APR_BUCKET_IS_METADATA(bucket)) {
if (bucket->length == (apr_size_t)-1) {
/*
* A setaside of morphing buckets would read everything into
* memory. Instead, we will flush everything up to and
* including this bucket.
*/
morphing_bucket_in_brigade = 1;
}
else {
bytes_in_brigade += bucket->length;
if (!APR_BUCKET_IS_FILE(bucket))
non_file_bytes_in_brigade += bucket->length;
}
}
else if (AP_BUCKET_IS_EOR(bucket)) {
eor_buckets_in_brigade++;
}
if (APR_BUCKET_IS_FLUSH(bucket)
|| non_file_bytes_in_brigade >= THRESHOLD_MAX_BUFFER
|| morphing_bucket_in_brigade
|| eor_buckets_in_brigade > MAX_REQUESTS_IN_PIPELINE) {
/* this segment of the brigade MUST be sent before returning. */
if (loglevel >= APLOG_TRACE6) {
char *reason = APR_BUCKET_IS_FLUSH(bucket) ?
"FLUSH bucket" :
(non_file_bytes_in_brigade >= THRESHOLD_MAX_BUFFER) ?
"THRESHOLD_MAX_BUFFER" :
morphing_bucket_in_brigade ? "morphing bucket" :
"MAX_REQUESTS_IN_PIPELINE";
ap_log_cerror(APLOG_MARK, APLOG_TRACE6, 0, c,
"will flush because of %s", reason);
ap_log_cerror(APLOG_MARK, APLOG_TRACE8, 0, c,
"seen in brigade%s: bytes: %" APR_SIZE_T_FMT
", non-file bytes: %" APR_SIZE_T_FMT ", eor "
"buckets: %d, morphing buckets: %d",
flush_upto == NULL ? " so far"
: " since last flush point",
bytes_in_brigade,
non_file_bytes_in_brigade,
eor_buckets_in_brigade,
morphing_bucket_in_brigade);
}
/*
* Defer the actual blocking write to avoid doing many writes.
*/
flush_upto = next;
bytes_in_brigade = 0;
non_file_bytes_in_brigade = 0;
eor_buckets_in_brigade = 0;
morphing_bucket_in_brigade = 0;
}
}
if (flush_upto != NULL) {
ctx->tmp_flush_bb = apr_brigade_split_ex(bb, flush_upto,
ctx->tmp_flush_bb);
if (loglevel >= APLOG_TRACE8) {
ap_log_cerror(APLOG_MARK, APLOG_TRACE8, 0, c,
"flushing now");
}
rv = send_brigade_blocking(net->client_socket, bb,
&(ctx->bytes_written), c);
if (rv != APR_SUCCESS) {
/* The client has aborted the connection */
ap_log_cerror(APLOG_MARK, APLOG_TRACE1, rv, c,
"core_output_filter: writing data to the network");
apr_brigade_cleanup(bb);
c->aborted = 1;
return rv;
}
if (loglevel >= APLOG_TRACE8) {
ap_log_cerror(APLOG_MARK, APLOG_TRACE8, 0, c,
"total bytes written: %" APR_SIZE_T_FMT,
ctx->bytes_written);
}
APR_BRIGADE_CONCAT(bb, ctx->tmp_flush_bb);
}
if (loglevel >= APLOG_TRACE8) {
ap_log_cerror(APLOG_MARK, APLOG_TRACE8, 0, c,
"brigade contains: bytes: %" APR_SIZE_T_FMT
", non-file bytes: %" APR_SIZE_T_FMT
", eor buckets: %d, morphing buckets: %d",
bytes_in_brigade, non_file_bytes_in_brigade,
eor_buckets_in_brigade, morphing_bucket_in_brigade);
}
if (bytes_in_brigade >= THRESHOLD_MIN_WRITE) {
rv = send_brigade_nonblocking(net->client_socket, bb,
&(ctx->bytes_written), c);
if ((rv != APR_SUCCESS) && (!APR_STATUS_IS_EAGAIN(rv))) {
/* The client has aborted the connection */
ap_log_cerror(APLOG_MARK, APLOG_TRACE1, rv, c,
"core_output_filter: writing data to the network");
apr_brigade_cleanup(bb);
c->aborted = 1;
return rv;
}
if (loglevel >= APLOG_TRACE8) {
ap_log_cerror(APLOG_MARK, APLOG_TRACE8, 0, c,
"tried nonblocking write, total bytes "
"written: %" APR_SIZE_T_FMT,
ctx->bytes_written);
}
}
setaside_remaining_output(f, ctx, bb, c);
return APR_SUCCESS;
}
/* Bring the data from the brigade (which represents the result of the
* request_rec out filter chain) into the h2_mplx for further sending
* on the master connection.
*/
static apr_status_t slave_out(h2_task *task, ap_filter_t* f,
apr_bucket_brigade* bb)
{
apr_bucket *b;
apr_status_t status = APR_SUCCESS;
int flush = 0, blocking;
if (task->frozen) {
h2_util_bb_log(task->c, task->stream_id, APLOG_TRACE2,
"frozen task output write, ignored", bb);
while (!APR_BRIGADE_EMPTY(bb)) {
b = APR_BRIGADE_FIRST(bb);
if (AP_BUCKET_IS_EOR(b)) {
APR_BUCKET_REMOVE(b);
task->eor = b;
}
else {
apr_bucket_delete(b);
}
}
return APR_SUCCESS;
}
/* we send block once we opened the output, so someone is there
* reading it *and* the task is not assigned to a h2_req_engine */
blocking = (!task->assigned && task->output.opened);
if (!task->output.opened) {
for (b = APR_BRIGADE_FIRST(bb);
b != APR_BRIGADE_SENTINEL(bb);
b = APR_BUCKET_NEXT(b)) {
if (APR_BUCKET_IS_FLUSH(b)) {
flush = 1;
break;
}
}
}
if (task->output.bb && !APR_BRIGADE_EMPTY(task->output.bb)) {
/* still have data buffered from previous attempt.
* setaside and append new data and try to pass the complete data */
if (!APR_BRIGADE_EMPTY(bb)) {
status = ap_save_brigade(f, &task->output.bb, &bb, task->pool);
}
if (status == APR_SUCCESS) {
status = send_out(task, task->output.bb, blocking);
}
}
else {
/* no data buffered here, try to pass the brigade directly */
status = send_out(task, bb, blocking);
if (status == APR_SUCCESS && !APR_BRIGADE_EMPTY(bb)) {
/* could not write all, buffer the rest */
ap_log_cerror(APLOG_MARK, APLOG_DEBUG, status, task->c, APLOGNO(03405)
"h2_slave_out(%s): saving brigade",
task->id);
status = ap_save_brigade(f, &task->output.bb, &bb, task->pool);
flush = 1;
}
}
if (status == APR_SUCCESS && !task->output.opened && flush) {
/* got a flush or could not write all, time to tell someone to read */
status = open_output(task);
}
ap_log_cerror(APLOG_MARK, APLOG_TRACE2, status, task->c,
"h2_slave_out(%s): slave_out leave", task->id);
return status;
}