Adding upstream version 2.4.56.upstream/2.4.56upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1191 insertions, 0 deletions

diff --git a/modules/http2/h2_mplx.c b/modules/http2/h2_mplx.c
new file mode 100644
index 0000000..99c47ea
--- /dev/null
+++ b/modules/http2/h2_mplx.c
@@ -0,0 +1,1191 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+ 
+#include <assert.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+#include <apr_atomic.h>
+#include <apr_thread_mutex.h>
+#include <apr_thread_cond.h>
+#include <apr_strings.h>
+#include <apr_time.h>
+
+#include <httpd.h>
+#include <http_core.h>
+#include <http_connection.h>
+#include <http_log.h>
+#include <http_protocol.h>
+
+#include <mpm_common.h>
+
+#include "mod_http2.h"
+
+#include "h2.h"
+#include "h2_private.h"
+#include "h2_bucket_beam.h"
+#include "h2_config.h"
+#include "h2_c1.h"
+#include "h2_conn_ctx.h"
+#include "h2_protocol.h"
+#include "h2_mplx.h"
+#include "h2_request.h"
+#include "h2_stream.h"
+#include "h2_session.h"
+#include "h2_c2.h"
+#include "h2_workers.h"
+#include "h2_util.h"
+
+
+/* utility for iterating over ihash stream sets */
+typedef struct {
+    h2_mplx *m;
+    h2_stream *stream;
+    apr_time_t now;
+    apr_size_t count;
+} stream_iter_ctx;
+
+static conn_rec *c2_prod_next(void *baton, int *phas_more);
+static void c2_prod_done(void *baton, conn_rec *c2);
+static void workers_shutdown(void *baton, int graceful);
+
+static void s_mplx_be_happy(h2_mplx *m, conn_rec *c, h2_conn_ctx_t *conn_ctx);
+static void m_be_annoyed(h2_mplx *m);
+
+static apr_status_t mplx_pollset_create(h2_mplx *m);
+static apr_status_t mplx_pollset_poll(h2_mplx *m, apr_interval_time_t timeout,
+                            stream_ev_callback *on_stream_input,
+                            stream_ev_callback *on_stream_output,
+                            void *on_ctx);
+
+static apr_pool_t *pchild;
+
+/* APR callback invoked if allocation fails. */
+static int abort_on_oom(int retcode)
+{
+    ap_abort_on_oom();
+    return retcode; /* unreachable, hopefully. */
+}
+
+apr_status_t h2_mplx_c1_child_init(apr_pool_t *pool, server_rec *s)
+{
+    pchild = pool;
+    return APR_SUCCESS;
+}
+
+#define H2_MPLX_ENTER(m)    \
+    do { apr_status_t rv_lock; if ((rv_lock = apr_thread_mutex_lock(m->lock)) != APR_SUCCESS) {\
+        return rv_lock;\
+    } } while(0)
+
+#define H2_MPLX_LEAVE(m)    \
+    apr_thread_mutex_unlock(m->lock)
+ 
+#define H2_MPLX_ENTER_ALWAYS(m)    \
+    apr_thread_mutex_lock(m->lock)
+
+#define H2_MPLX_ENTER_MAYBE(m, dolock)    \
+    if (dolock) apr_thread_mutex_lock(m->lock)
+
+#define H2_MPLX_LEAVE_MAYBE(m, dolock)    \
+    if (dolock) apr_thread_mutex_unlock(m->lock)
+
+static void c1_input_consumed(void *ctx, h2_bucket_beam *beam, apr_off_t length)
+{
+    h2_stream_in_consumed(ctx, length);
+}
+
+static int stream_is_running(h2_stream *stream)
+{
+    h2_conn_ctx_t *conn_ctx = h2_conn_ctx_get(stream->c2);
+    return conn_ctx && apr_atomic_read32(&conn_ctx->started) != 0
+        && apr_atomic_read32(&conn_ctx->done) == 0;
+}
+
+int h2_mplx_c1_stream_is_running(h2_mplx *m, h2_stream *stream)
+{
+    int rv;
+
+    H2_MPLX_ENTER(m);
+    rv = stream_is_running(stream);
+    H2_MPLX_LEAVE(m);
+    return rv;
+}
+
+static void c1c2_stream_joined(h2_mplx *m, h2_stream *stream)
+{
+    ap_assert(!stream_is_running(stream));
+    
+    h2_ihash_remove(m->shold, stream->id);
+    APR_ARRAY_PUSH(m->spurge, h2_stream *) = stream;
+}
+
+static void m_stream_cleanup(h2_mplx *m, h2_stream *stream)
+{
+    h2_conn_ctx_t *c2_ctx = h2_conn_ctx_get(stream->c2);
+
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, m->c1,
+                  H2_STRM_MSG(stream, "cleanup, unsubscribing from beam events"));
+    if (c2_ctx) {
+        if (c2_ctx->beam_out) {
+            h2_beam_on_was_empty(c2_ctx->beam_out, NULL, NULL);
+        }
+        if (c2_ctx->beam_in) {
+            h2_beam_on_send(c2_ctx->beam_in, NULL, NULL);
+            h2_beam_on_received(c2_ctx->beam_in, NULL, NULL);
+            h2_beam_on_consumed(c2_ctx->beam_in, NULL, NULL);
+        }
+    }
+
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, m->c1,
+                  H2_STRM_MSG(stream, "cleanup, removing from registries"));
+    ap_assert(stream->state == H2_SS_CLEANUP);
+    h2_stream_cleanup(stream);
+    h2_ihash_remove(m->streams, stream->id);
+    h2_iq_remove(m->q, stream->id);
+
+    if (c2_ctx) {
+        if (!stream_is_running(stream)) {
+            ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, m->c1,
+                          H2_STRM_MSG(stream, "cleanup, c2 is done, move to spurge"));
+            /* processing has finished */
+            APR_ARRAY_PUSH(m->spurge, h2_stream *) = stream;
+        }
+        else {
+            ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, m->c1,
+                          H2_STRM_MSG(stream, "cleanup, c2 is running, abort"));
+            /* c2 is still running */
+            h2_c2_abort(stream->c2, m->c1);
+            ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, m->c1,
+                          H2_STRM_MSG(stream, "cleanup, c2 is done, move to shold"));
+            h2_ihash_add(m->shold, stream);
+        }
+    }
+    else {
+        /* never started */
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, m->c1,
+                      H2_STRM_MSG(stream, "cleanup, never started, move to spurge"));
+        APR_ARRAY_PUSH(m->spurge, h2_stream *) = stream;
+    }
+}
+
+static h2_c2_transit *c2_transit_create(h2_mplx *m)
+{
+    apr_allocator_t *allocator;
+    apr_pool_t *ptrans;
+    h2_c2_transit *transit;
+    apr_status_t rv;
+
+    /* We create a pool with its own allocator to be used for
+     * processing a request. This is the only way to have the processing
+     * independent of its parent pool in the sense that it can work in
+     * another thread.
+     */
+
+    rv = apr_allocator_create(&allocator);
+    if (rv == APR_SUCCESS) {
+        apr_allocator_max_free_set(allocator, ap_max_mem_free);
+        rv = apr_pool_create_ex(&ptrans, m->pool, NULL, allocator);
+    }
+    if (rv != APR_SUCCESS) {
+        /* maybe the log goes through, maybe not. */
+        ap_log_cerror(APLOG_MARK, APLOG_ERR, rv, m->c1,
+                      APLOGNO(10004) "h2_mplx: create transit pool");
+        ap_abort_on_oom();
+        return NULL; /* should never be reached. */
+    }
+
+    apr_allocator_owner_set(allocator, ptrans);
+    apr_pool_abort_set(abort_on_oom, ptrans);
+    apr_pool_tag(ptrans, "h2_c2_transit");
+
+    transit = apr_pcalloc(ptrans, sizeof(*transit));
+    transit->pool = ptrans;
+    transit->bucket_alloc = apr_bucket_alloc_create(ptrans);
+    return transit;
+}
+
+static void c2_transit_destroy(h2_c2_transit *transit)
+{
+    apr_pool_destroy(transit->pool);
+}
+
+static h2_c2_transit *c2_transit_get(h2_mplx *m)
+{
+    h2_c2_transit **ptransit = apr_array_pop(m->c2_transits);
+    if (ptransit) {
+        return *ptransit;
+    }
+    return c2_transit_create(m);
+}
+
+static void c2_transit_recycle(h2_mplx *m, h2_c2_transit *transit)
+{
+    if (m->c2_transits->nelts >= APR_INT32_MAX ||
+        (apr_uint32_t)m->c2_transits->nelts >= m->max_spare_transits) {
+        c2_transit_destroy(transit);
+    }
+    else {
+        APR_ARRAY_PUSH(m->c2_transits, h2_c2_transit*) = transit;
+    }
+}
+
+/**
+ * A h2_mplx needs to be thread-safe *and* if will be called by
+ * the h2_session thread *and* the h2_worker threads. Therefore:
+ * - calls are protected by a mutex lock, m->lock
+ * - the pool needs its own allocator, since apr_allocator_t are 
+ *   not re-entrant. The separate allocator works without a 
+ *   separate lock since we already protect h2_mplx itself.
+ *   Since HTTP/2 connections can be expected to live longer than
+ *   their HTTP/1 cousins, the separate allocator seems to work better
+ *   than protecting a shared h2_session one with an own lock.
+ */
+h2_mplx *h2_mplx_c1_create(int child_num, apr_uint32_t id, h2_stream *stream0,
+                           server_rec *s, apr_pool_t *parent,
+                           h2_workers *workers)
+{
+    h2_conn_ctx_t *conn_ctx;
+    apr_status_t status = APR_SUCCESS;
+    apr_allocator_t *allocator;
+    apr_thread_mutex_t *mutex = NULL;
+    h2_mplx *m = NULL;
+    
+    m = apr_pcalloc(parent, sizeof(h2_mplx));
+    m->stream0 = stream0;
+    m->c1 = stream0->c2;
+    m->s = s;
+    m->child_num = child_num;
+    m->id = id;
+
+    /* We create a pool with its own allocator to be used for
+     * processing secondary connections. This is the only way to have the
+     * processing independent of its parent pool in the sense that it
+     * can work in another thread. Also, the new allocator needs its own
+     * mutex to synchronize sub-pools.
+     */
+    status = apr_allocator_create(&allocator);
+    if (status != APR_SUCCESS) {
+        allocator = NULL;
+        goto failure;
+    }
+
+    apr_allocator_max_free_set(allocator, ap_max_mem_free);
+    apr_pool_create_ex(&m->pool, parent, NULL, allocator);
+    if (!m->pool) goto failure;
+
+    apr_pool_tag(m->pool, "h2_mplx");
+    apr_allocator_owner_set(allocator, m->pool);
+
+    status = apr_thread_mutex_create(&mutex, APR_THREAD_MUTEX_DEFAULT,
+                                     m->pool);
+    if (APR_SUCCESS != status) goto failure;
+    apr_allocator_mutex_set(allocator, mutex);
+
+    status = apr_thread_mutex_create(&m->lock, APR_THREAD_MUTEX_DEFAULT,
+                                     m->pool);
+    if (APR_SUCCESS != status) goto failure;
+
+    m->max_streams = h2_config_sgeti(s, H2_CONF_MAX_STREAMS);
+    m->stream_max_mem = h2_config_sgeti(s, H2_CONF_STREAM_MAX_MEM);
+
+    m->streams = h2_ihash_create(m->pool, offsetof(h2_stream,id));
+    m->shold = h2_ihash_create(m->pool, offsetof(h2_stream,id));
+    m->spurge = apr_array_make(m->pool, 10, sizeof(h2_stream*));
+    m->q = h2_iq_create(m->pool, m->max_streams);
+
+    m->workers = workers;
+    m->processing_max = H2MIN(h2_workers_get_max_workers(workers), m->max_streams);
+    m->processing_limit = 6; /* the original h1 max parallel connections */
+    m->last_mood_change = apr_time_now();
+    m->mood_update_interval = apr_time_from_msec(100);
+
+    status = mplx_pollset_create(m);
+    if (APR_SUCCESS != status) {
+        ap_log_cerror(APLOG_MARK, APLOG_ERR, status, m->c1, APLOGNO(10308)
+                      "nghttp2: could not create pollset");
+        goto failure;
+    }
+    m->streams_ev_in = apr_array_make(m->pool, 10, sizeof(h2_stream*));
+    m->streams_ev_out = apr_array_make(m->pool, 10, sizeof(h2_stream*));
+
+    m->streams_input_read = h2_iq_create(m->pool, 10);
+    m->streams_output_written = h2_iq_create(m->pool, 10);
+    status = apr_thread_mutex_create(&m->poll_lock, APR_THREAD_MUTEX_DEFAULT,
+                                     m->pool);
+    if (APR_SUCCESS != status) goto failure;
+
+    conn_ctx = h2_conn_ctx_get(m->c1);
+    if (conn_ctx->pfd.reqevents) {
+        apr_pollset_add(m->pollset, &conn_ctx->pfd);
+    }
+
+    m->scratch_r = apr_pcalloc(m->pool, sizeof(*m->scratch_r));
+    m->max_spare_transits = 3;
+    m->c2_transits = apr_array_make(m->pool, (int)m->max_spare_transits,
+                                    sizeof(h2_c2_transit*));
+
+    m->producer = h2_workers_register(workers, m->pool,
+                                      apr_psprintf(m->pool, "h2-%u",
+                                      (unsigned int)m->id),
+                                      c2_prod_next, c2_prod_done,
+                                      workers_shutdown, m);
+    return m;
+
+failure:
+    if (m->pool) {
+        apr_pool_destroy(m->pool);
+    }
+    else if (allocator) {
+        apr_allocator_destroy(allocator);
+    }
+    return NULL;
+}
+
+int h2_mplx_c1_shutdown(h2_mplx *m)
+{
+    int max_stream_id_started = 0;
+    
+    H2_MPLX_ENTER(m);
+
+    max_stream_id_started = m->max_stream_id_started;
+    /* Clear schedule queue, disabling existing streams from starting */ 
+    h2_iq_clear(m->q);
+
+    H2_MPLX_LEAVE(m);
+    return max_stream_id_started;
+}
+
+typedef struct {
+    h2_mplx_stream_cb *cb;
+    void *ctx;
+} stream_iter_ctx_t;
+
+static int m_stream_iter_wrap(void *ctx, void *stream)
+{
+    stream_iter_ctx_t *x = ctx;
+    return x->cb(stream, x->ctx);
+}
+
+apr_status_t h2_mplx_c1_streams_do(h2_mplx *m, h2_mplx_stream_cb *cb, void *ctx)
+{
+    stream_iter_ctx_t x;
+    
+    H2_MPLX_ENTER(m);
+
+    x.cb = cb;
+    x.ctx = ctx;
+    h2_ihash_iter(m->streams, m_stream_iter_wrap, &x);
+        
+    H2_MPLX_LEAVE(m);
+    return APR_SUCCESS;
+}
+
+static int m_report_stream_iter(void *ctx, void *val) {
+    h2_mplx *m = ctx;
+    h2_stream *stream = val;
+    h2_conn_ctx_t *conn_ctx = h2_conn_ctx_get(stream->c2);
+    ap_log_cerror(APLOG_MARK, APLOG_WARNING, 0, m->c1,
+                  H2_STRM_MSG(stream, "started=%d, scheduled=%d, ready=%d, out_buffer=%ld"),
+                  !!stream->c2, stream->scheduled, h2_stream_is_ready(stream),
+                  (long)(stream->output? h2_beam_get_buffered(stream->output) : -1));
+    if (conn_ctx) {
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, m->c1, /* NO APLOGNO */
+                      H2_STRM_MSG(stream, "->03198: %s %s %s"
+                      "[started=%u/done=%u]"),
+                      conn_ctx->request->method, conn_ctx->request->authority,
+                      conn_ctx->request->path,
+                      apr_atomic_read32(&conn_ctx->started),
+                      apr_atomic_read32(&conn_ctx->done));
+    }
+    else {
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, m->c1, /* NO APLOGNO */
+                      H2_STRM_MSG(stream, "->03198: not started"));
+    }
+    return 1;
+}
+
+static int m_unexpected_stream_iter(void *ctx, void *val) {
+    h2_mplx *m = ctx;
+    h2_stream *stream = val;
+    ap_log_cerror(APLOG_MARK, APLOG_WARNING, 0, m->c1, /* NO APLOGNO */
+                  H2_STRM_MSG(stream, "unexpected, started=%d, scheduled=%d, ready=%d"), 
+                  !!stream->c2, stream->scheduled, h2_stream_is_ready(stream));
+    return 1;
+}
+
+static int m_stream_cancel_iter(void *ctx, void *val) {
+    h2_mplx *m = ctx;
+    h2_stream *stream = val;
+
+    /* take over event monitoring */
+    h2_stream_set_monitor(stream, NULL);
+    /* Reset, should transit to CLOSED state */
+    h2_stream_rst(stream, H2_ERR_NO_ERROR);
+    /* All connection data has been sent, simulate cleanup */
+    h2_stream_dispatch(stream, H2_SEV_EOS_SENT);
+    m_stream_cleanup(m, stream);  
+    return 0;
+}
+
+void h2_mplx_c1_destroy(h2_mplx *m)
+{
+    apr_status_t status;
+    unsigned int i, wait_secs = 60;
+    int old_aborted;
+
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, m->c1,
+                  H2_MPLX_MSG(m, "start release"));
+    /* How to shut down a h2 connection:
+     * 0. abort and tell the workers that no more work will come from us */
+    m->shutdown = m->aborted = 1;
+
+    H2_MPLX_ENTER_ALWAYS(m);
+
+    /* While really terminating any c2 connections, treat the master
+     * connection as aborted. It's not as if we could send any more data
+     * at this point. */
+    old_aborted = m->c1->aborted;
+    m->c1->aborted = 1;
+
+    /* How to shut down a h2 connection:
+     * 1. cancel all streams still active */
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, m->c1,
+                  H2_MPLX_MSG(m, "release, %u/%u/%d streams (total/hold/purge), %d streams"),
+                  h2_ihash_count(m->streams),
+                  h2_ihash_count(m->shold),
+                  m->spurge->nelts, m->processing_count);
+    while (!h2_ihash_iter(m->streams, m_stream_cancel_iter, m)) {
+        /* until empty */
+    }
+    
+    /* 2. no more streams should be scheduled or in the active set */
+    ap_assert(h2_ihash_empty(m->streams));
+    ap_assert(h2_iq_empty(m->q));
+    
+    /* 3. while workers are busy on this connection, meaning they
+     *    are processing streams from this connection, wait on them finishing
+     *    in order to wake us and let us check again. 
+     *    Eventually, this has to succeed. */
+    if (!m->join_wait) {
+        apr_thread_cond_create(&m->join_wait, m->pool);
+    }
+
+    for (i = 0; h2_ihash_count(m->shold) > 0; ++i) {
+        status = apr_thread_cond_timedwait(m->join_wait, m->lock, apr_time_from_sec(wait_secs));
+        
+        if (APR_STATUS_IS_TIMEUP(status)) {
+            /* This can happen if we have very long running requests
+             * that do not time out on IO. */
+            ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, m->c1, APLOGNO(03198)
+                          H2_MPLX_MSG(m, "waited %u sec for %u streams"),
+                          i*wait_secs, h2_ihash_count(m->shold));
+            h2_ihash_iter(m->shold, m_report_stream_iter, m);
+        }
+    }
+
+    H2_MPLX_LEAVE(m);
+    h2_workers_join(m->workers, m->producer);
+    H2_MPLX_ENTER_ALWAYS(m);
+
+    /* 4. With all workers done, all streams should be in spurge */
+    ap_assert(m->processing_count == 0);
+    if (!h2_ihash_empty(m->shold)) {
+        ap_log_cerror(APLOG_MARK, APLOG_WARNING, 0, m->c1, APLOGNO(03516)
+                      H2_MPLX_MSG(m, "unexpected %u streams in hold"),
+                      h2_ihash_count(m->shold));
+        h2_ihash_iter(m->shold, m_unexpected_stream_iter, m);
+    }
+    
+    m->c1->aborted = old_aborted;
+    H2_MPLX_LEAVE(m);
+
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, m->c1,
+                  H2_MPLX_MSG(m, "released"));
+}
+
+apr_status_t h2_mplx_c1_stream_cleanup(h2_mplx *m, h2_stream *stream,
+                                       unsigned int *pstream_count)
+{
+    H2_MPLX_ENTER(m);
+    
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, m->c1,
+                  H2_STRM_MSG(stream, "cleanup"));
+    m_stream_cleanup(m, stream);
+    *pstream_count = h2_ihash_count(m->streams);
+    H2_MPLX_LEAVE(m);
+    return APR_SUCCESS;
+}
+
+const h2_stream *h2_mplx_c2_stream_get(h2_mplx *m, int stream_id)
+{
+    h2_stream *s = NULL;
+    
+    H2_MPLX_ENTER_ALWAYS(m);
+    s = h2_ihash_get(m->streams, stream_id);
+    H2_MPLX_LEAVE(m);
+
+    return s;
+}
+
+
+static void c1_update_scoreboard(h2_mplx *m, h2_stream *stream)
+{
+    if (stream->c2) {
+        m->scratch_r->connection = stream->c2;
+        m->scratch_r->bytes_sent = stream->out_frame_octets;
+        ap_increment_counts(m->c1->sbh, m->scratch_r);
+        m->scratch_r->connection = NULL;
+    }
+}
+
+static void c1_purge_streams(h2_mplx *m)
+{
+    h2_stream *stream;
+    int i;
+
+    for (i = 0; i < m->spurge->nelts; ++i) {
+        stream = APR_ARRAY_IDX(m->spurge, i, h2_stream*);
+        ap_assert(stream->state == H2_SS_CLEANUP);
+
+        c1_update_scoreboard(m, stream);
+
+        if (stream->input) {
+            h2_beam_destroy(stream->input, m->c1);
+            stream->input = NULL;
+        }
+        if (stream->c2) {
+            conn_rec *c2 = stream->c2;
+            h2_conn_ctx_t *c2_ctx = h2_conn_ctx_get(c2);
+            h2_c2_transit *transit;
+
+            stream->c2 = NULL;
+            ap_assert(c2_ctx);
+            transit = c2_ctx->transit;
+            h2_c2_destroy(c2);  /* c2_ctx is gone as well */
+            if (transit) {
+                c2_transit_recycle(m, transit);
+            }
+        }
+        h2_stream_destroy(stream);
+    }
+    apr_array_clear(m->spurge);
+}
+
+apr_status_t h2_mplx_c1_poll(h2_mplx *m, apr_interval_time_t timeout,
+                            stream_ev_callback *on_stream_input,
+                            stream_ev_callback *on_stream_output,
+                            void *on_ctx)
+{
+    apr_status_t rv;
+
+    H2_MPLX_ENTER(m);
+
+    if (m->aborted) {
+        rv = APR_ECONNABORTED;
+        goto cleanup;
+    }
+    /* Purge (destroy) streams outside of pollset processing.
+     * Streams that are registered in the pollset, will be removed
+     * when they are destroyed, but the pollset works on copies
+     * of these registrations. So, if we destroy streams while
+     * processing pollset events, we might access freed memory.
+     */
+    if (m->spurge->nelts) {
+        c1_purge_streams(m);
+    }
+    rv = mplx_pollset_poll(m, timeout, on_stream_input, on_stream_output, on_ctx);
+
+cleanup:
+    H2_MPLX_LEAVE(m);
+    return rv;
+}
+
+apr_status_t h2_mplx_c1_reprioritize(h2_mplx *m, h2_stream_pri_cmp_fn *cmp,
+                                    h2_session *session)
+{
+    apr_status_t status;
+    
+    H2_MPLX_ENTER(m);
+
+    if (m->aborted) {
+        status = APR_ECONNABORTED;
+    }
+    else {
+        h2_iq_sort(m->q, cmp, session);
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, m->c1,
+                      H2_MPLX_MSG(m, "reprioritize streams"));
+        status = APR_SUCCESS;
+    }
+
+    H2_MPLX_LEAVE(m);
+    return status;
+}
+
+static apr_status_t c1_process_stream(h2_mplx *m,
+                                      h2_stream *stream,
+                                      h2_stream_pri_cmp_fn *cmp,
+                                      h2_session *session)
+{
+    apr_status_t rv = APR_SUCCESS;
+
+    if (m->aborted) {
+        rv = APR_ECONNABORTED;
+        goto cleanup;
+    }
+    if (!stream->request) {
+        rv = APR_EINVAL;
+        goto cleanup;
+    }
+    if (APLOGctrace1(m->c1)) {
+        const h2_request *r = stream->request;
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, m->c1,
+                      H2_STRM_MSG(stream, "process %s %s://%s%s"),
+                      r->method, r->scheme, r->authority, r->path);
+    }
+
+    stream->scheduled = 1;
+    h2_ihash_add(m->streams, stream);
+    if (h2_stream_is_ready(stream)) {
+        /* already have a response */
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, m->c1,
+                      H2_STRM_MSG(stream, "process, ready already"));
+    }
+    else {
+        /* last chance to set anything up before stream is processed
+         * by worker threads. */
+        rv = h2_stream_prepare_processing(stream);
+        if (APR_SUCCESS != rv) goto cleanup;
+        h2_iq_add(m->q, stream->id, cmp, session);
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, m->c1,
+                      H2_STRM_MSG(stream, "process, added to q"));
+    }
+
+cleanup:
+    return rv;
+}
+
+void h2_mplx_c1_process(h2_mplx *m,
+                        h2_iqueue *ready_to_process,
+                        h2_stream_get_fn *get_stream,
+                        h2_stream_pri_cmp_fn *stream_pri_cmp,
+                        h2_session *session,
+                        unsigned int *pstream_count)
+{
+    apr_status_t rv;
+    int sid;
+
+    H2_MPLX_ENTER_ALWAYS(m);
+
+    while ((sid = h2_iq_shift(ready_to_process)) > 0) {
+        h2_stream *stream = get_stream(session, sid);
+        if (stream) {
+            ap_assert(!stream->scheduled);
+            rv = c1_process_stream(session->mplx, stream, stream_pri_cmp, session);
+            if (APR_SUCCESS != rv) {
+                h2_stream_rst(stream, H2_ERR_INTERNAL_ERROR);
+            }
+        }
+        else {
+            ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, m->c1,
+                          H2_MPLX_MSG(m, "stream %d not found to process"), sid);
+        }
+    }
+    if ((m->processing_count < m->processing_limit) && !h2_iq_empty(m->q)) {
+        H2_MPLX_LEAVE(m);
+        rv = h2_workers_activate(m->workers, m->producer);
+        H2_MPLX_ENTER_ALWAYS(m);
+        if (rv != APR_SUCCESS) {
+            ap_log_cerror(APLOG_MARK, APLOG_ERR, rv, m->c1, APLOGNO(10021)
+                          H2_MPLX_MSG(m, "activate at workers"));
+        }
+    }
+    *pstream_count = h2_ihash_count(m->streams);
+
+#if APR_POOL_DEBUG
+    do {
+        apr_size_t mem_g, mem_m, mem_s, mem_c1;
+
+        mem_g = pchild? apr_pool_num_bytes(pchild, 1) : 0;
+        mem_m = apr_pool_num_bytes(m->pool, 1);
+        mem_s = apr_pool_num_bytes(session->pool, 1);
+        mem_c1 = apr_pool_num_bytes(m->c1->pool, 1);
+        ap_log_cerror(APLOG_MARK, APLOG_INFO, 0, m->c1,
+                      H2_MPLX_MSG(m, "child mem=%ld, mplx mem=%ld, session mem=%ld, c1=%ld"),
+                      (long)mem_g, (long)mem_m, (long)mem_s, (long)mem_c1);
+
+    } while (0);
+#endif
+
+    H2_MPLX_LEAVE(m);
+}
+
+static void c2_beam_input_write_notify(void *ctx, h2_bucket_beam *beam)
+{
+    conn_rec *c = ctx;
+    h2_conn_ctx_t *conn_ctx = h2_conn_ctx_get(c);
+
+    (void)beam;
+    if (conn_ctx && conn_ctx->stream_id && conn_ctx->pipe_in[H2_PIPE_IN]) {
+        apr_file_putc(1, conn_ctx->pipe_in[H2_PIPE_IN]);
+    }
+}
+
+static void add_stream_poll_event(h2_mplx *m, int stream_id, h2_iqueue *q)
+{
+    apr_thread_mutex_lock(m->poll_lock);
+    if (h2_iq_append(q, stream_id) && h2_iq_count(q) == 1) {
+        /* newly added first */
+        apr_pollset_wakeup(m->pollset);
+    }
+    apr_thread_mutex_unlock(m->poll_lock);
+}
+
+static void c2_beam_input_read_notify(void *ctx, h2_bucket_beam *beam)
+{
+    conn_rec *c = ctx;
+    h2_conn_ctx_t *conn_ctx = h2_conn_ctx_get(c);
+
+    if (conn_ctx && conn_ctx->stream_id) {
+        add_stream_poll_event(conn_ctx->mplx, conn_ctx->stream_id,
+                              conn_ctx->mplx->streams_input_read);
+    }
+}
+
+static void c2_beam_output_write_notify(void *ctx, h2_bucket_beam *beam)
+{
+    conn_rec *c = ctx;
+    h2_conn_ctx_t *conn_ctx = h2_conn_ctx_get(c);
+
+    if (conn_ctx && conn_ctx->stream_id) {
+        add_stream_poll_event(conn_ctx->mplx, conn_ctx->stream_id,
+                              conn_ctx->mplx->streams_output_written);
+    }
+}
+
+static apr_status_t c2_setup_io(h2_mplx *m, conn_rec *c2, h2_stream *stream, h2_c2_transit *transit)
+{
+    h2_conn_ctx_t *conn_ctx;
+    apr_status_t rv = APR_SUCCESS;
+    const char *action = "init";
+
+    rv = h2_conn_ctx_init_for_c2(&conn_ctx, c2, m, stream, transit);
+    if (APR_SUCCESS != rv) goto cleanup;
+
+    if (!conn_ctx->beam_out) {
+        action = "create output beam";
+        rv = h2_beam_create(&conn_ctx->beam_out, c2, conn_ctx->req_pool,
+                            stream->id, "output", 0, c2->base_server->timeout);
+        if (APR_SUCCESS != rv) goto cleanup;
+
+        h2_beam_buffer_size_set(conn_ctx->beam_out, m->stream_max_mem);
+        h2_beam_on_was_empty(conn_ctx->beam_out, c2_beam_output_write_notify, c2);
+    }
+
+    memset(&conn_ctx->pipe_in, 0, sizeof(conn_ctx->pipe_in));
+    if (stream->input) {
+        conn_ctx->beam_in = stream->input;
+        h2_beam_on_send(stream->input, c2_beam_input_write_notify, c2);
+        h2_beam_on_received(stream->input, c2_beam_input_read_notify, c2);
+        h2_beam_on_consumed(stream->input, c1_input_consumed, stream);
+#if H2_USE_PIPES
+        action = "create input write pipe";
+        rv = apr_file_pipe_create_pools(&conn_ctx->pipe_in[H2_PIPE_OUT],
+                                        &conn_ctx->pipe_in[H2_PIPE_IN],
+                                        APR_READ_BLOCK,
+                                        c2->pool, c2->pool);
+        if (APR_SUCCESS != rv) goto cleanup;
+#endif
+    }
+
+cleanup:
+    stream->output = (APR_SUCCESS == rv)? conn_ctx->beam_out : NULL;
+    if (APR_SUCCESS != rv) {
+        ap_log_cerror(APLOG_MARK, APLOG_ERR, rv, c2,
+                      H2_STRM_LOG(APLOGNO(10309), stream,
+                      "error %s"), action);
+    }
+    return rv;
+}
+
+static conn_rec *s_next_c2(h2_mplx *m)
+{
+    h2_stream *stream = NULL;
+    apr_status_t rv = APR_SUCCESS;
+    apr_uint32_t sid;
+    conn_rec *c2 = NULL;
+    h2_c2_transit *transit = NULL;
+
+    while (!m->aborted && !stream && (m->processing_count < m->processing_limit)
+           && (sid = h2_iq_shift(m->q)) > 0) {
+        stream = h2_ihash_get(m->streams, sid);
+    }
+
+    if (!stream) {
+        if (m->processing_count >= m->processing_limit && !h2_iq_empty(m->q)) {
+            ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, m->c1,
+                          H2_MPLX_MSG(m, "delaying request processing. "
+                          "Current limit is %d and %d workers are in use."),
+                          m->processing_limit, m->processing_count);
+        }
+        goto cleanup;
+    }
+
+    if (sid > m->max_stream_id_started) {
+        m->max_stream_id_started = sid;
+    }
+
+    transit = c2_transit_get(m);
+#if AP_HAS_RESPONSE_BUCKETS
+    c2 = ap_create_secondary_connection(transit->pool, m->c1, transit->bucket_alloc);
+#else
+    c2 = h2_c2_create(m->c1, transit->pool, transit->bucket_alloc);
+#endif
+    if (!c2) goto cleanup;
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE3, 0, m->c1,
+                  H2_STRM_MSG(stream, "created new c2"));
+
+    rv = c2_setup_io(m, c2, stream, transit);
+    if (APR_SUCCESS != rv) goto cleanup;
+
+    stream->c2 = c2;
+    ++m->processing_count;
+
+cleanup:
+    if (APR_SUCCESS != rv && c2) {
+        h2_c2_destroy(c2);
+        c2 = NULL;
+    }
+    if (transit && !c2) {
+        c2_transit_recycle(m, transit);
+    }
+    return c2;
+}
+
+static conn_rec *c2_prod_next(void *baton, int *phas_more)
+{
+    h2_mplx *m = baton;
+    conn_rec *c = NULL;
+
+    H2_MPLX_ENTER_ALWAYS(m);
+    if (!m->aborted) {
+        c = s_next_c2(m);
+        *phas_more = (c != NULL && !h2_iq_empty(m->q));
+    }
+    H2_MPLX_LEAVE(m);
+    return c;
+}
+
+static void s_c2_done(h2_mplx *m, conn_rec *c2, h2_conn_ctx_t *conn_ctx)
+{
+    h2_stream *stream;
+
+    ap_assert(conn_ctx);
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, c2,
+                  "h2_mplx(%s-%d): c2 done", conn_ctx->id, conn_ctx->stream_id);
+
+    AP_DEBUG_ASSERT(apr_atomic_read32(&conn_ctx->done) == 0);
+    apr_atomic_set32(&conn_ctx->done, 1);
+    conn_ctx->done_at = apr_time_now();
+    ++c2->keepalives;
+    /* From here on, the final handling of c2 is done by c1 processing.
+     * Which means we can give it c1's scoreboard handle for updates. */
+    c2->sbh = m->c1->sbh;
+
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, c2,
+                  "h2_mplx(%s-%d): request done, %f ms elapsed",
+                  conn_ctx->id, conn_ctx->stream_id,
+                  (conn_ctx->done_at - conn_ctx->started_at) / 1000.0);
+    
+    if (!conn_ctx->has_final_response) {
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, conn_ctx->last_err, c2,
+                      "h2_c2(%s-%d): processing finished without final response",
+                      conn_ctx->id, conn_ctx->stream_id);
+        c2->aborted = 1;
+    }
+    else if (!c2->aborted) {
+        s_mplx_be_happy(m, c2, conn_ctx);
+    }
+    
+    stream = h2_ihash_get(m->streams, conn_ctx->stream_id);
+    if (stream) {
+        /* stream not done yet. trigger a potential polling on the output
+         * since nothing more will happening here. */
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, c2,
+                      H2_STRM_MSG(stream, "c2_done, stream open"));
+        c2_beam_output_write_notify(c2, NULL);
+    }
+    else if ((stream = h2_ihash_get(m->shold, conn_ctx->stream_id)) != NULL) {
+        /* stream is done, was just waiting for this. */
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, c2,
+                      H2_STRM_MSG(stream, "c2_done, in hold"));
+        c1c2_stream_joined(m, stream);
+    }
+    else {
+        int i;
+
+        for (i = 0; i < m->spurge->nelts; ++i) {
+            if (stream == APR_ARRAY_IDX(m->spurge, i, h2_stream*)) {
+                ap_log_cerror(APLOG_MARK, APLOG_WARNING, 0, c2,
+                              H2_STRM_LOG(APLOGNO(03517), stream, "already in spurge"));
+                ap_assert("stream should not be in spurge" == NULL);
+                return;
+            }
+        }
+
+        ap_log_cerror(APLOG_MARK, APLOG_WARNING, 0, c2, APLOGNO(03518)
+                      "h2_mplx(%s-%d): c2_done, stream not found",
+                      conn_ctx->id, conn_ctx->stream_id);
+        ap_assert("stream should still be available" == NULL);
+    }
+}
+
+static void c2_prod_done(void *baton, conn_rec *c2)
+{
+    h2_mplx *m = baton;
+    h2_conn_ctx_t *conn_ctx = h2_conn_ctx_get(c2);
+
+    AP_DEBUG_ASSERT(conn_ctx);
+    H2_MPLX_ENTER_ALWAYS(m);
+
+    --m->processing_count;
+    s_c2_done(m, c2, conn_ctx);
+    if (m->join_wait) apr_thread_cond_signal(m->join_wait);
+
+    H2_MPLX_LEAVE(m);
+}
+
+static void workers_shutdown(void *baton, int graceful)
+{
+    h2_mplx *m = baton;
+
+    apr_thread_mutex_lock(m->poll_lock);
+    /* time to wakeup and assess what to do */
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, m->c1,
+                  H2_MPLX_MSG(m, "workers shutdown, waking pollset"));
+    m->shutdown = 1;
+    if (!graceful) {
+        m->aborted = 1;
+    }
+    apr_pollset_wakeup(m->pollset);
+    apr_thread_mutex_unlock(m->poll_lock);
+}
+
+/*******************************************************************************
+ * h2_mplx DoS protection
+ ******************************************************************************/
+
+static void s_mplx_be_happy(h2_mplx *m, conn_rec *c, h2_conn_ctx_t *conn_ctx)
+{
+    apr_time_t now;            
+
+    if (m->processing_limit < m->processing_max
+        && conn_ctx->started_at > m->last_mood_change) {
+        --m->irritations_since;
+        if (m->processing_limit < m->processing_max
+            && ((now = apr_time_now()) - m->last_mood_change >= m->mood_update_interval
+                || m->irritations_since < -m->processing_limit)) {
+            m->processing_limit = H2MIN(m->processing_limit * 2, m->processing_max);
+            m->last_mood_change = now;
+            m->irritations_since = 0;
+            ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, c,
+                          H2_MPLX_MSG(m, "mood update, increasing worker limit to %d"),
+                          m->processing_limit);
+        }
+    }
+}
+
+static void m_be_annoyed(h2_mplx *m)
+{
+    apr_time_t now;
+
+    if (m->processing_limit > 2) {
+        ++m->irritations_since;
+        if (((now = apr_time_now()) - m->last_mood_change >= m->mood_update_interval)
+            || (m->irritations_since >= m->processing_limit)) {
+
+            if (m->processing_limit > 16) {
+                m->processing_limit = 16;
+            }
+            else if (m->processing_limit > 8) {
+                m->processing_limit = 8;
+            }
+            else if (m->processing_limit > 4) {
+                m->processing_limit = 4;
+            }
+            else if (m->processing_limit > 2) {
+                m->processing_limit = 2;
+            }
+            m->last_mood_change = now;
+            m->irritations_since = 0;
+            ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, m->c1,
+                          H2_MPLX_MSG(m, "mood update, decreasing worker limit to %d"),
+                          m->processing_limit);
+        }
+    }
+}
+
+/*******************************************************************************
+ * mplx master events dispatching
+ ******************************************************************************/
+
+static int reset_is_acceptable(h2_stream *stream)
+{
+    /* client may terminate a stream via H2 RST_STREAM message at any time.
+     * This is annyoing when we have committed resources (e.g. worker threads)
+     * to it, so our mood (e.g. willingness to commit resources on this
+     * connection in the future) goes down.
+     *
+     * This is a DoS protection. We do not want to make it too easy for
+     * a client to eat up server resources.
+     *
+     * However: there are cases where a RST_STREAM is the only way to end
+     * a request. This includes websockets and server-side-event streams (SSEs).
+     * The responses to such requests continue forever otherwise.
+     *
+     */
+    if (!stream_is_running(stream)) return 1;
+    if (!(stream->id & 0x01)) return 1; /* stream initiated by us. acceptable. */
+    if (!stream->response) return 0; /* no response headers produced yet. bad. */
+    if (!stream->out_data_frames) return 0; /* no response body data sent yet. bad. */
+    return 1; /* otherwise, be forgiving */
+}
+
+apr_status_t h2_mplx_c1_client_rst(h2_mplx *m, int stream_id)
+{
+    h2_stream *stream;
+    apr_status_t status = APR_SUCCESS;
+
+    H2_MPLX_ENTER_ALWAYS(m);
+    stream = h2_ihash_get(m->streams, stream_id);
+    if (stream && !reset_is_acceptable(stream)) {
+        m_be_annoyed(m);
+    }
+    H2_MPLX_LEAVE(m);
+    return status;
+}
+
+static apr_status_t mplx_pollset_create(h2_mplx *m)
+{
+    /* stream0 output only */
+    return apr_pollset_create(&m->pollset, 1, m->pool,
+                              APR_POLLSET_WAKEABLE);
+}
+
+static apr_status_t mplx_pollset_poll(h2_mplx *m, apr_interval_time_t timeout,
+                            stream_ev_callback *on_stream_input,
+                            stream_ev_callback *on_stream_output,
+                            void *on_ctx)
+{
+    apr_status_t rv;
+    const apr_pollfd_t *results, *pfd;
+    apr_int32_t nresults, i;
+    h2_conn_ctx_t *conn_ctx;
+    h2_stream *stream;
+
+    /* Make sure we are not called recursively. */
+    ap_assert(!m->polling);
+    m->polling = 1;
+    do {
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, m->c1,
+                      H2_MPLX_MSG(m, "enter polling timeout=%d"),
+                      (int)apr_time_sec(timeout));
+
+        apr_array_clear(m->streams_ev_in);
+        apr_array_clear(m->streams_ev_out);
+
+        do {
+            /* add streams we started processing in the meantime */
+            apr_thread_mutex_lock(m->poll_lock);
+            if (!h2_iq_empty(m->streams_input_read)
+                || !h2_iq_empty(m->streams_output_written)) {
+                while ((i = h2_iq_shift(m->streams_input_read))) {
+                    stream = h2_ihash_get(m->streams, i);
+                    if (stream) {
+                        APR_ARRAY_PUSH(m->streams_ev_in, h2_stream*) = stream;
+                    }
+                }
+                while ((i = h2_iq_shift(m->streams_output_written))) {
+                    stream = h2_ihash_get(m->streams, i);
+                    if (stream) {
+                        APR_ARRAY_PUSH(m->streams_ev_out, h2_stream*) = stream;
+                    }
+                }
+                nresults = 0;
+                rv = APR_SUCCESS;
+                apr_thread_mutex_unlock(m->poll_lock);
+                break;
+            }
+            apr_thread_mutex_unlock(m->poll_lock);
+
+            H2_MPLX_LEAVE(m);
+            rv = apr_pollset_poll(m->pollset, timeout >= 0? timeout : -1, &nresults, &results);
+            H2_MPLX_ENTER_ALWAYS(m);
+            if (APR_STATUS_IS_EINTR(rv) && m->shutdown) {
+                if (!m->aborted) {
+                    rv = APR_SUCCESS;
+                }
+                goto cleanup;
+            }
+        } while (APR_STATUS_IS_EINTR(rv));
+
+        if (APR_SUCCESS != rv) {
+            if (APR_STATUS_IS_TIMEUP(rv)) {
+                ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, m->c1,
+                              H2_MPLX_MSG(m, "polling timed out "));
+            }
+            else {
+                ap_log_cerror(APLOG_MARK, APLOG_ERR, rv, m->c1, APLOGNO(10310) \
+                              H2_MPLX_MSG(m, "polling failed"));
+            }
+            goto cleanup;
+        }
+
+        for (i = 0; i < nresults; i++) {
+            pfd = &results[i];
+            conn_ctx = pfd->client_data;
+
+            AP_DEBUG_ASSERT(conn_ctx);
+            if (conn_ctx->stream_id == 0) {
+                if (on_stream_input) {
+                    APR_ARRAY_PUSH(m->streams_ev_in, h2_stream*) = m->stream0;
+                }
+                continue;
+            }
+        }
+
+        if (on_stream_input && m->streams_ev_in->nelts) {
+            H2_MPLX_LEAVE(m);
+            for (i = 0; i < m->streams_ev_in->nelts; ++i) {
+                on_stream_input(on_ctx, APR_ARRAY_IDX(m->streams_ev_in, i, h2_stream*));
+            }
+            H2_MPLX_ENTER_ALWAYS(m);
+        }
+        if (on_stream_output && m->streams_ev_out->nelts) {
+            H2_MPLX_LEAVE(m);
+            for (i = 0; i < m->streams_ev_out->nelts; ++i) {
+                on_stream_output(on_ctx, APR_ARRAY_IDX(m->streams_ev_out, i, h2_stream*));
+            }
+            H2_MPLX_ENTER_ALWAYS(m);
+        }
+        break;
+    } while(1);
+
+cleanup:
+    m->polling = 0;
+    return rv;
+}
+