[PATCH] 'clogging' input filters and the event MPM

[Paul Querna <ch...@force-elite.com>]

Attached is a patch that should let people run mod_ssl under the Event MPM.

Previously, the event mpm would put a socket into its event thread to
wait for input, but due to issues with how mod_ssl might be buffering
data (or the entire request) in it, this would cause SSL'ized requests
to stall and fail with the event mpm.

The attach patch adds a new field, clogging_input_filters, to the
conn_rec. When this field is true, the event mpm will run a connection
just like the worker mpm is -- that is a single thread will run the
entire connection, including keepalives.

Thoughts on committing this to trunk?

Thanks,

-Paul

Re: [PATCH] 'clogging' input filters and the event MPM

[Jim Jagielski <ji...@jaguNET.com>]

+1 (concept)

On Jun 10, 2007, at 9:13 PM, Paul Querna wrote:

> Attached is a patch that should let people run mod_ssl under the  
> Event MPM.
>
> Previously, the event mpm would put a socket into its event thread to
> wait for input, but due to issues with how mod_ssl might be buffering
> data (or the entire request) in it, this would cause SSL'ized requests
> to stall and fail with the event mpm.
>
> The attach patch adds a new field, clogging_input_filters, to the
> conn_rec. When this field is true, the event mpm will run a connection
> just like the worker mpm is -- that is a single thread will run the
> entire connection, including keepalives.
>
> Thoughts on committing this to trunk?
>
> Thanks,
>
> -Paul
> Index: server/mpm/experimental/event/event.c
> ===================================================================
> --- server/mpm/experimental/event/event.c	(revision 545614)
> +++ server/mpm/experimental/event/event.c	(working copy)
> @@ -620,6 +620,16 @@
>          pt = cs->pfd.client_data;
>      }
>
> +    if (c->clogging_input_filters && !c->aborted) {
> +        /* Since we have an input filter which 'cloggs' the input  
> stream,
> +         * like mod_ssl, lets just do the normal read from input  
> filters,
> +         * like the Worker MPM does.
> +         */
> +        ap_run_process_connection(c);
> +        ap_lingering_close(c);
> +        return 0;
> +    }
> +
>  read_request:
>      if (cs->state == CONN_STATE_READ_REQUEST_LINE) {
>          if (!c->aborted) {
> Index: server/core.c
> ===================================================================
> --- server/core.c	(revision 545614)
> +++ server/core.c	(working copy)
> @@ -3803,6 +3803,7 @@
>      c->cs->c = c;
>      c->cs->p = ptrans;
>      c->cs->bucket_alloc = alloc;
> +    c->clogging_input_filters = 0;
>
>      return c;
>  }
> Index: modules/http/http_core.c
> ===================================================================
> --- modules/http/http_core.c	(revision 545614)
> +++ modules/http/http_core.c	(working copy)
> @@ -119,11 +119,17 @@
>      return DEFAULT_HTTP_PORT;
>  }
>
> +static int ap_process_http_connection(conn_rec *c);
> +
>  static int ap_process_http_async_connection(conn_rec *c)
>  {
>      request_rec *r;
>      conn_state_t *cs = c->cs;
>
> +    if (c->clogging_input_filters) {
> +        return ap_process_http_connection(c);
> +    }
> +
>      AP_DEBUG_ASSERT(cs->state == CONN_STATE_READ_REQUEST_LINE);
>
>      while (cs->state == CONN_STATE_READ_REQUEST_LINE) {
> Index: modules/ssl/ssl_engine_io.c
> ===================================================================
> --- modules/ssl/ssl_engine_io.c	(revision 545614)
> +++ modules/ssl/ssl_engine_io.c	(working copy)
> @@ -1665,6 +1665,9 @@
>      filter_ctx->pbioWrite       = BIO_new(&bio_filter_out_method);
>      filter_ctx->pbioWrite->ptr  = (void *)bio_filter_out_ctx_new 
> (filter_ctx, c);
>
> +    /* We insert a clogging input filter. Let the core know. */
> +    c->clogging_input_filters = 1;
> +
>      ssl_io_input_add_filter(filter_ctx, c, ssl);
>
>      SSL_set_bio(ssl, filter_ctx->pbioRead, filter_ctx->pbioWrite);
> Index: include/httpd.h
> ===================================================================
> --- include/httpd.h	(revision 545614)
> +++ include/httpd.h	(working copy)
> @@ -1081,6 +1081,11 @@
>      int data_in_input_filters;
>      /** Is there data pending in the output filters? */
>      int data_in_output_filters;
> +
> +    /** Are there any filters that clogg/buffer the input stream,  
> breaking
> +     *  the event mpm.
> +     */
> +    int clogging_input_filters;
>  };
>
>  /**