core: always allocate filters (ap_filter_t) on f->c->pool.

When filters are allocated on f->r->pool, they may be destroyed any time
underneath themselves which makes it hard for them to be passed the EOR and
forward it (*f can't be dereferenced anymore when the EOR is destroyed, thus
before request filters return).

On the util_filter side, it also makes it impossible to flush pending request
filters when they have set aside the EOR, since f->bb can't be accessed after
it's passed to the f->next.

So we always use f->c->pool to allocate filters and pending brigades, and to
avoid leaks with keepalive requests (long living connections handling multiple
requests), filters and brigades are recycled with a cleanup on f->r->pool.

Recycling is done (generically) with a spare data ring (void pointers), and a
filter(s) context struct is associated with the conn_rec to maintain the rings
by connection, that is:

    struct ap_filter_conn_ctx {
        struct ap_filter_ring *pending_input_filters;
        struct ap_filter_ring *pending_output_filters;

        struct ap_filter_spare_ring *spare_containers,
                                    *spare_brigades,
                                    *spare_filters,
                                    *spare_flushes;
        int flushing;
    };

MMN major bumped (again).


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1839997 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 10 insertions, 13 deletions

diff --git a/include/ap_mmn.h b/include/ap_mmn.h
index bfd36d5fa5..be63709a52 100644
--- a/include/ap_mmn.h
+++ b/include/ap_mmn.h
@@ -598,13 +598,15 @@
  * 20180720.7 (2.5.1-dev)  worker_share struct re-organized
  * 20180902.1 (2.5.1-dev)  Split conn_rec pending_filters in two rings,
  *                         pending_input_filters and pending_output_filters
- *
+ * 20180903.1 (2.5.1-dev)  Replace conn_rec pending_{in,out}put_filters by
+ *                         filter_conn_ctx, remove argument pool from
+ *                         ap_filter_prepare_brigade()
  */
 
 #define MODULE_MAGIC_COOKIE 0x41503235UL /* "AP25" */
 
 #ifndef MODULE_MAGIC_NUMBER_MAJOR
-#define MODULE_MAGIC_NUMBER_MAJOR 20180902
+#define MODULE_MAGIC_NUMBER_MAJOR 20180903
 #endif
 #define MODULE_MAGIC_NUMBER_MINOR 1                 /* 0...n */
 
diff --git a/include/httpd.h b/include/httpd.h
index 808e3d4caf..977c042897 100644
--- a/include/httpd.h
+++ b/include/httpd.h
@@ -1111,7 +1111,7 @@ typedef enum {
     AP_CONN_KEEPALIVE
 } ap_conn_keepalive_e;
 
-/* For struct ap_filter and ap_filter_ring */
+/* For struct ap_filter_conn_ctx */
 #include "util_filter.h"
 
 /**
@@ -1224,10 +1224,8 @@ struct conn_rec {
     /** Array of requests being handled under this connection. */
     apr_array_header_t *requests;
 
-    /** Ring of pending input filters (with setaside buckets) */
-    struct ap_filter_ring *pending_input_filters;
-    /** Ring of pending output filters (with setaside buckets) */
-    struct ap_filter_ring *pending_output_filters;
+    /** Filters' context for this connection */
+    struct ap_filter_conn_ctx *filter_conn_ctx;
 
     /** The minimum level of filter type to allow setaside buckets */
     int async_filter;
diff --git a/include/util_filter.h b/include/util_filter.h
index e863bfe7a1..0417d3015c 100644
--- a/include/util_filter.h
+++ b/include/util_filter.h
@@ -304,9 +304,9 @@ struct ap_filter_t {
 };
 
 /**
- * @brief The type of a filters' ring (opaque).
+ * @brief The filters' context in conn_rec (opaque).
  */
-typedef struct ap_filter_ring ap_filter_ring_t;
+struct ap_filter_conn_ctx;
 
 /**
  * Get the current bucket brigade from the next filter on the filter
@@ -569,12 +569,9 @@ AP_DECLARE(apr_status_t) ap_save_brigade(ap_filter_t *f,
  * filters, or can be used within an output filter by being called via
  * ap_filter_setaside_brigade().
  * @param f The current filter
- * @param p The pool that was used to create the brigade. In a request
- * filter this will be the request pool, in a connection filter this will
- * be the connection pool.
  * @returns OK if a brigade was created, DECLINED otherwise.
  */
-AP_DECLARE(int) ap_filter_prepare_brigade(ap_filter_t *f, apr_pool_t **p);
+AP_DECLARE(int) ap_filter_prepare_brigade(ap_filter_t *f);
 
 /**
  * Prepare a bucket brigade to be setaside, creating a dedicated pool if