remove locking in utility classes

* we need full restructuring to be thread-safe, so there's no
  point in having locking (with potential for deadlocks) in
  these particular utility classes at this time.

4 files changed, 19 insertions, 44 deletions

diff --git a/slobrok/src/vespa/slobrok/server/service_map_history.cpp b/slobrok/src/vespa/slobrok/server/service_map_history.cpp
index 5a2f8c6ff43..551ea367bc9 100644
--- a/slobrok/src/vespa/slobrok/server/service_map_history.cpp
+++ b/slobrok/src/vespa/slobrok/server/service_map_history.cpp
@@ -43,8 +43,7 @@ ServiceMapHistory::UpdateLog::updatedSince(const Generation &gen) const {
 //-----------------------------------------------------------------------------
 
 ServiceMapHistory::ServiceMapHistory()
-  : _lock(),
-    _map(),
+  : _map(),
     _waitList(),
     _log()
 {}
@@ -56,63 +55,49 @@ ServiceMapHistory::~ServiceMapHistory() {
 
 void ServiceMapHistory::notify_updated() {
     WaitList waitList;
-    {
-        std::lock_guard guard(_lock);
-        std::swap(waitList, _waitList);
-    }
+    std::swap(waitList, _waitList);
     for (auto & [ handler, gen ] : waitList) {
         handler->handle(makeDiffFrom(gen));
     }
 }
 
 void ServiceMapHistory::asyncGenerationDiff(DiffCompletionHandler *handler, const Generation &fromGen) {
-    {
-        std::lock_guard guard(_lock);
-        if (fromGen == myGen()) {
-            _waitList.emplace_back(handler, fromGen);
-            return;
-        }
+    if (fromGen == myGen()) {
+        _waitList.emplace_back(handler, fromGen);
+        return;
     }
     handler->handle(makeDiffFrom(fromGen));
 }
 
 bool ServiceMapHistory::cancel(DiffCompletionHandler *handler) {
-    std::lock_guard guard(_lock);
     size_t removed = std::erase_if(_waitList, [=](const Waiter &elem){ return elem.first == handler; });
     return (removed > 0);
 }
 
 void ServiceMapHistory::remove(const ServiceMapping &mapping) {
-    {
-        std::lock_guard guard(_lock);
-        auto iter = _map.find(mapping.name);
-        if (iter == _map.end()) {
-            LOG(debug, "already removed: %s", mapping.name.c_str());
-            return; // already removed
-        }
-        LOG_ASSERT(iter->second == mapping.spec);
-        _map.erase(iter);
-        _log.add(mapping.name);
+    auto iter = _map.find(mapping.name);
+    if (iter == _map.end()) {
+        LOG(debug, "already removed: %s", mapping.name.c_str());
+        return; // already removed
     }
+    LOG_ASSERT(iter->second == mapping.spec);
+    _map.erase(iter);
+    _log.add(mapping.name);
     notify_updated();
 }
 
 void ServiceMapHistory::add(const ServiceMapping &mapping) {
-    {
-        std::lock_guard guard(_lock);
-        auto iter = _map.find(mapping.name);
-        if (iter != _map.end() && iter->second == mapping.spec) {
-            // already ok
-            return;
-        }
-        _map.insert_or_assign(mapping.name, mapping.spec);
-        _log.add(mapping.name);
+    auto iter = _map.find(mapping.name);
+    if (iter != _map.end() && iter->second == mapping.spec) {
+        // already ok
+        return;
     }
+    _map.insert_or_assign(mapping.name, mapping.spec);
+    _log.add(mapping.name);
     notify_updated();
 }
 
 MapDiff ServiceMapHistory::makeDiffFrom(const Generation &fromGen) const {
-    std::lock_guard guard(_lock);
     if (_log.isInRange(fromGen)) {
         std::vector<vespalib::string> removes;
         ServiceMappingList updates;
diff --git a/slobrok/src/vespa/slobrok/server/service_map_history.h b/slobrok/src/vespa/slobrok/server/service_map_history.h
index 9026586b945..726ba778ca2 100644
--- a/slobrok/src/vespa/slobrok/server/service_map_history.h
+++ b/slobrok/src/vespa/slobrok/server/service_map_history.h
@@ -6,7 +6,6 @@
 #include <vespa/vespalib/util/gencnt.h>
 #include <vespa/vespalib/util/arrayqueue.hpp>
 #include <map>
-#include <mutex>
 #include "map_listener.h"
 #include "service_mapping.h"
 #include "map_diff.h"
@@ -52,7 +51,6 @@ private:
     using Waiter = std::pair<DiffCompletionHandler *, Generation>;
     using WaitList = std::vector<Waiter>;
 
-    mutable std::mutex _lock;
     Map        _map;
     WaitList   _waitList;
     UpdateLog  _log;
diff --git a/slobrok/src/vespa/slobrok/server/service_map_mirror.cpp b/slobrok/src/vespa/slobrok/server/service_map_mirror.cpp
index 51db84e24a4..90deaa0f09c 100644
--- a/slobrok/src/vespa/slobrok/server/service_map_mirror.cpp
+++ b/slobrok/src/vespa/slobrok/server/service_map_mirror.cpp
@@ -8,8 +8,7 @@ namespace slobrok {
 
 ServiceMapMirror::ServiceMapMirror()
   : _map(),
-    _currGen(0),
-    _lock()
+    _currGen(0)
 {}
 
 ServiceMapMirror::~ServiceMapMirror() {
@@ -17,7 +16,6 @@ ServiceMapMirror::~ServiceMapMirror() {
 }
 
 void ServiceMapMirror::apply(const MapDiff &diff) {
-    std::lock_guard guard(_lock);
     LOG(debug, "Applying diff from gen %u", diff.fromGen.getAsInt());
     LOG_ASSERT(diff.fromGen == _currGen);
     for (const auto & name : diff.removed) {
@@ -54,7 +52,6 @@ void ServiceMapMirror::apply(const MapDiff &diff) {
 }
 
 void ServiceMapMirror::clear() {
-    std::lock_guard guard(_lock);
     for (const auto & [ k, v ] : _map) {
         ServiceMapping mapping{k, v};
         for (auto * listener : _listeners) {
@@ -66,7 +63,6 @@ void ServiceMapMirror::clear() {
 }
 
 ServiceMappingList ServiceMapMirror::allMappings() const {
-    std::lock_guard guard(_lock);
     ServiceMappingList result;
     result.reserve(_map.size());
     for (const auto & [ k, v ] : _map) {
@@ -76,12 +72,10 @@ ServiceMappingList ServiceMapMirror::allMappings() const {
 }
 
 void ServiceMapMirror::registerListener(MapListener &listener) {
-    std::lock_guard guard(_lock);
     _listeners.insert(&listener);
 }
 
 void ServiceMapMirror::unregisterListener(MapListener &listener) {
-    std::lock_guard guard(_lock);
     _listeners.erase(&listener);
 }
 
diff --git a/slobrok/src/vespa/slobrok/server/service_map_mirror.h b/slobrok/src/vespa/slobrok/server/service_map_mirror.h
index 4cd1c91b7f1..7418aeaec92 100644
--- a/slobrok/src/vespa/slobrok/server/service_map_mirror.h
+++ b/slobrok/src/vespa/slobrok/server/service_map_mirror.h
@@ -7,7 +7,6 @@
 #include "map_source.h"
 #include <vespa/vespalib/util/gencnt.h>
 #include <map>
-#include <mutex>
 #include <set>
 
 namespace slobrok {
@@ -41,7 +40,6 @@ private:
     using Map = std::map<vespalib::string, vespalib::string>;
     Map _map;
     Generation _currGen;
-    mutable std::mutex _lock;
     std::set<MapListener *> _listeners;
 };