nghttpx: Fix bug that mruby is incorrectly shared between backends

Previously, mruby context is wrongly shared by multiple patterns if
the underlying SharedDownstreamAddr is shared by multiple
DownstreamAddrGroups.  This commit fixes it.

src/shrpx_downstream.cc

@@ -193,7 +193,7 @@ Downstream::~Downstream() {
   if (dconn_) {
     const auto &group = dconn_->get_downstream_addr_group();
     if (group) {
-      const auto &mruby_ctx = group->mruby_ctx;
+      const auto &mruby_ctx = group->shared_addr->mruby_ctx;
       mruby_ctx->delete_downstream(this);
     }
   }
@@ -231,7 +231,7 @@ void Downstream::detach_downstream_connection() {
 #ifdef HAVE_MRUBY
   const auto &group = dconn_->get_downstream_addr_group();
   if (group) {
-    const auto &mruby_ctx = group->mruby_ctx;
+    const auto &mruby_ctx = group->shared_addr->mruby_ctx;
     mruby_ctx->delete_downstream(this);
   }
 #endif // HAVE_MRUBY
@@ -256,7 +256,7 @@ std::unique_ptr<DownstreamConnection> Downstream::pop_downstream_connection() {
 
   const auto &group = dconn_->get_downstream_addr_group();
   if (group) {
-    const auto &mruby_ctx = group->mruby_ctx;
+    const auto &mruby_ctx = group->shared_addr->mruby_ctx;
     mruby_ctx->delete_downstream(this);
   }
 #endif // HAVE_MRUBY

src/shrpx_http2_upstream.cc

@@ -492,7 +492,7 @@ void Http2Upstream::initiate_downstream(Downstream *downstream) {
 #ifdef HAVE_MRUBY
   const auto &group = dconn_ptr->get_downstream_addr_group();
   if (group) {
-    const auto &mruby_ctx = group->mruby_ctx;
+    const auto &mruby_ctx = group->shared_addr->mruby_ctx;
     if (mruby_ctx->run_on_request_proc(downstream) != 0) {
       if (error_reply(downstream, 500) != 0) {
         rst_stream(downstream, NGHTTP2_INTERNAL_ERROR);
@@ -1665,7 +1665,7 @@ int Http2Upstream::on_downstream_header_complete(Downstream *downstream) {
     auto dconn = downstream->get_downstream_connection();
     const auto &group = dconn->get_downstream_addr_group();
     if (group) {
-      const auto &dmruby_ctx = group->mruby_ctx;
+      const auto &dmruby_ctx = group->shared_addr->mruby_ctx;
 
       if (dmruby_ctx->run_on_response_proc(downstream) != 0) {
         if (error_reply(downstream, 500) != 0) {

src/shrpx_https_upstream.cc

@@ -481,7 +481,7 @@ int htp_hdrs_completecb(llhttp_t *htp) {
 #ifdef HAVE_MRUBY
   const auto &group = dconn_ptr->get_downstream_addr_group();
   if (group) {
-    const auto &dmruby_ctx = group->mruby_ctx;
+    const auto &dmruby_ctx = group->shared_addr->mruby_ctx;
 
     if (dmruby_ctx->run_on_request_proc(downstream) != 0) {
       resp.http_status = 500;
@@ -1087,7 +1087,7 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
     assert(dconn);
     const auto &group = dconn->get_downstream_addr_group();
     if (group) {
-      const auto &dmruby_ctx = group->mruby_ctx;
+      const auto &dmruby_ctx = group->shared_addr->mruby_ctx;
 
       if (dmruby_ctx->run_on_response_proc(downstream) != 0) {
         error_reply(500);

src/shrpx_worker.cc

@@ -79,11 +79,12 @@ using DownstreamKey =
                                       size_t, Proto, uint32_t, uint32_t,
                                       uint32_t, bool, bool, bool, bool>>,
                bool, SessionAffinity, StringRef, StringRef,
-               SessionAffinityCookieSecure, int64_t, int64_t>;
+               SessionAffinityCookieSecure, int64_t, int64_t, StringRef>;
 
 namespace {
-DownstreamKey create_downstream_key(
-    const std::shared_ptr<SharedDownstreamAddr> &shared_addr) {
+DownstreamKey
+create_downstream_key(const std::shared_ptr<SharedDownstreamAddr> &shared_addr,
+                      const StringRef &mruby_file) {
   DownstreamKey dkey;
 
   auto &addrs = std::get<0>(dkey);
@@ -117,6 +118,7 @@ DownstreamKey create_downstream_key(
   auto &timeout = shared_addr->timeout;
   std::get<6>(dkey) = timeout.read;
   std::get<7>(dkey) = timeout.write;
+  std::get<8>(dkey) = mruby_file;
 
   return dkey;
 }
@@ -231,16 +233,6 @@ void Worker::replace_downstream_config(
     dst = std::make_shared<DownstreamAddrGroup>();
     dst->pattern =
         ImmutableString{std::begin(src.pattern), std::end(src.pattern)};
-#ifdef HAVE_MRUBY
-    auto mruby_ctx_it = shared_mruby_ctxs.find(src.mruby_file);
-    if (mruby_ctx_it == std::end(shared_mruby_ctxs)) {
-      dst->mruby_ctx = mruby::create_mruby_context(src.mruby_file);
-      assert(dst->mruby_ctx);
-      shared_mruby_ctxs.emplace(src.mruby_file, dst->mruby_ctx);
-    } else {
-      dst->mruby_ctx = (*mruby_ctx_it).second;
-    }
-#endif // HAVE_MRUBY
 
     auto shared_addr = std::make_shared<SharedDownstreamAddr>();
 
@@ -297,10 +289,21 @@ void Worker::replace_downstream_config(
           loop_, cl_ssl_ctx_, this, &dst_addr, randgen_);
     }
 
+#ifdef HAVE_MRUBY
+    auto mruby_ctx_it = shared_mruby_ctxs.find(src.mruby_file);
+    if (mruby_ctx_it == std::end(shared_mruby_ctxs)) {
+      shared_addr->mruby_ctx = mruby::create_mruby_context(src.mruby_file);
+      assert(shared_addr->mruby_ctx);
+      shared_mruby_ctxs.emplace(src.mruby_file, shared_addr->mruby_ctx);
+    } else {
+      shared_addr->mruby_ctx = (*mruby_ctx_it).second;
+    }
+#endif // HAVE_MRUBY
+
     // share the connection if patterns have the same set of backend
     // addresses.
 
-    auto dkey = create_downstream_key(shared_addr);
+    auto dkey = create_downstream_key(shared_addr, src.mruby_file);
     auto it = addr_groups_indexer.find(dkey);
 
     if (it == std::end(addr_groups_indexer)) {

src/shrpx_worker.h

@@ -206,6 +206,9 @@ struct SharedDownstreamAddr {
   // Bunch of session affinity hash.  Only used if affinity ==
   // SessionAffinity::IP.
   std::vector<AffinityHash> affinity_hash;
+#ifdef HAVE_MRUBY
+  std::shared_ptr<mruby::MRubyContext> mruby_ctx;
+#endif // HAVE_MRUBY
   // Configuration for session affinity
   AffinityConfig affinity;
   // Session affinity
@@ -230,9 +233,6 @@ struct DownstreamAddrGroup {
 
   ImmutableString pattern;
   std::shared_ptr<SharedDownstreamAddr> shared_addr;
-#ifdef HAVE_MRUBY
-  std::shared_ptr<mruby::MRubyContext> mruby_ctx;
-#endif // HAVE_MRUBY
   // true if this group is no longer used for new request.  If this is
   // true, the connection made using one of address in shared_addr
   // must not be pooled.