search: combine callbacks in case of multiple equivalent puts

Author: aberaud

src/dht.cpp

@@ -93,7 +93,7 @@ Dht::shutdown(ShutdownCallback cb, bool stop)
                     r.second.done_cb(false, {});
                 sr.second->callbacks.clear();
                 for (const auto& a : sr.second->announce) {
-                    if (a.callback) a.callback(false, {});
+                    for (auto& cb : a.callbacks) cb(false, {});
                 }
                 sr.second->announce.clear();
                 sr.second->listeners.clear();

src/search.h

@@ -45,7 +45,7 @@ struct Dht::Announce {
     bool permanent;
     Sp<Value> value;
     time_point created;
-    DoneCallback callback;
+    std::vector<DoneCallback> callbacks;
 };
 
 struct Dht::SearchNode {
@@ -442,8 +442,9 @@ struct Dht::Search {
             g.second.done_cb = {};
         }
         for (auto& a : announce) {
-            a.callback(false, {});
-            a.callback = {};
+            for (auto& cb : a.callbacks)
+                cb(false, {});
+            a.callbacks.clear();
         }
     }
 
@@ -627,7 +628,9 @@ struct Dht::Search {
             return a.value->id == value->id;
         });
         if (a_sr == announce.end()) {
-            announce.emplace_back(Announce {permanent, value, created, callback});
+            auto& a = announce.emplace_back(Announce {permanent, value, created, {}} );
+            if (callback)
+                a.callbacks.emplace_back(std::move(callback));
             for (auto& n : nodes) {
                 n->probe_query.reset();
                 n->acked[value->id].req.reset();
@@ -636,23 +639,25 @@ struct Dht::Search {
             a_sr->permanent = permanent;
             a_sr->created = created;
             if (a_sr->value != value) {
+                // Value is updated, previous ops are failed
                 a_sr->value = value;
                 for (auto& n : nodes) {
                     n->acked[value->id].req.reset();
                     n->probe_query.reset();
                 }
-            }
-            if (isAnnounced(value->id)) {
-                if (a_sr->callback)
-                    a_sr->callback(true, {});
-                a_sr->callback = {};
+                for (auto& cb: a_sr->callbacks)
+                    cb(false, {});
+                a_sr->callbacks.clear();
+                if (callback)
+                    a_sr->callbacks.emplace_back(std::move(callback));
+            } else if (isAnnounced(value->id)) {
+                // Same value, already announced
                 if (callback)
                     callback(true, {});
-                return;
             } else {
-                if (a_sr->callback)
-                    a_sr->callback(false, {});
-                a_sr->callback = callback;
+                // Same value, not announced yet
+                if (callback)
+                    a_sr->callbacks.emplace_back(std::move(callback));
             }
         }
     }
@@ -722,8 +727,8 @@ struct Dht::Search {
             std::vector<DoneCallback> a_cbs;
             a_cbs.reserve(announce.size());
             for (auto ait = announce.begin() ; ait != announce.end(); ) {
-                if (ait->callback)
-                    a_cbs.emplace_back(std::move(ait->callback));
+                a_cbs.insert(a_cbs.end(), std::make_move_iterator(ait->callbacks.begin()), std::make_move_iterator(ait->callbacks.end()));
+                ait->callbacks.clear();
                 if (not ait->permanent)
                     ait = announce.erase(ait);
                 else
@@ -747,9 +752,11 @@ struct Dht::Search {
                 if (vid != Value::INVALID_ID and (!a.value || a.value->id != vid))
                     return true;
                 if (isAnnounced(a.value->id)) {
-                    if (a.callback) {
-                        a.callback(true, getNodes());
-                        a.callback = nullptr;
+                    if (!a.callbacks.empty()) {
+                        const auto& nodes = getNodes();
+                        for (auto& cb : a.callbacks)
+                            cb(true, nodes);
+                        a.callbacks.clear();
                     }
                     if (not a.permanent)
                         return false;