FOLD: Make PRT thread-safe

src/ripple/overlay/PeerReservationTable.h

@@ -30,8 +30,10 @@
 #include <boost/optional.hpp>
 #include <soci/soci.h>
 
+#include <mutex>
 #include <string>
 #include <unordered_set>
+#include <vector>
 
 namespace ripple {
 
@@ -53,6 +55,11 @@ struct PeerReservation final
         using beast::hash_append;
         hash_append(h, x.nodeId);
     }
+
+    friend bool operator<(PeerReservation const& a, PeerReservation const& b)
+    {
+        return a.nodeId < b.nodeId;
+    }
 };
 
 // TODO: When C++20 arrives, take advantage of "equivalence" instead of
@@ -80,33 +87,12 @@ class PeerReservationTable final
     {
     }
 
-    const_iterator
-    begin() const noexcept
-    {
-        return table_.begin();
-    }
-
-    const_iterator
-    cbegin() const noexcept
-    {
-        return table_.cbegin();
-    }
-
-    const_iterator
-    end() const noexcept
-    {
-        return table_.end();
-    }
-
-    const_iterator
-    cend() const noexcept
-    {
-        return table_.cend();
-    }
+    std::vector<PeerReservation> list() const;
 
     bool
     contains(PublicKey const& nodeId)
     {
+        std::lock_guard<std::mutex> lock(this->mutex_);
         return table_.find({nodeId}) != table_.end();
     }
 
@@ -131,6 +117,7 @@ class PeerReservationTable final
 
 private:
     beast::Journal mutable journal_;
+    std::mutex mutable mutex_;
     DatabaseCon* connection_;
     table_type table_;
 };

src/ripple/overlay/impl/PeerReservationTable.cpp

@@ -27,7 +27,11 @@
 
 #include <boost/optional.hpp>
 
+#include <algorithm>
+#include <iterator>
+#include <mutex>
 #include <string>
+#include <vector>
 
 namespace ripple {
 
@@ -43,6 +47,19 @@ PeerReservation::toJson() const -> Json::Value
     return result;
 }
 
+auto
+PeerReservationTable::list() const -> std::vector<PeerReservation>
+{
+    std::vector<PeerReservation> list;
+    list.reserve(table_.size());
+    {
+        std::lock_guard<std::mutex> lock(mutex_);
+        std::copy(table_.begin(), table_.end(), std::back_inserter(list));
+    }
+    std::sort(list.begin(), list.end());
+    return list;
+}
+
 // See `ripple/app/main/DBInit.cpp` for the `CREATE TABLE` statement.
 // It is unfortunate that we do not get to define a function for it.
 
@@ -52,6 +69,8 @@ PeerReservation::toJson() const -> Json::Value
 bool
 PeerReservationTable::load(DatabaseCon& connection)
 {
+    std::lock_guard<std::mutex> lock(mutex_);
+
     connection_ = &connection;
     auto db = connection_->checkoutDb();
 
@@ -92,6 +111,8 @@ PeerReservationTable::insert_or_assign(
 {
     boost::optional<PeerReservation> previous;
 
+    std::lock_guard<std::mutex> lock(mutex_);
+
     auto hint = table_.find(reservation);
     if (hint != table_.end()) {
         // The node already has a reservation. Remove it.
@@ -129,6 +150,8 @@ PeerReservationTable::erase(PublicKey const& nodeId)
 {
     boost::optional<PeerReservation> previous;
 
+    std::lock_guard<std::mutex> lock(mutex_);
+
     auto const it = table_.find({nodeId});
     if (it != table_.end())
     {

src/ripple/rpc/handlers/Reservations.cpp

@@ -115,7 +115,7 @@ doPeerReservationsDel(RPC::Context& context)
 Json::Value
 doPeerReservationsList(RPC::Context& context)
 {
-    auto const& reservations = context.app.peerReservations();
+    auto const& reservations = context.app.peerReservations().list();
     // Enumerate the reservations in context.app.peerReservations()
     // as a Json::Value.
     Json::Value result{Json::objectValue};