2 files changed, 29 insertions, 14 deletions

diff --git a/src/wallet/db.cpp b/src/wallet/db.cpp
index a0f0abd4a6..f7ffd0d6bf 100644
--- a/src/wallet/db.cpp
+++ b/src/wallet/db.cpp
@@ -107,13 +107,13 @@ void BerkeleyEnvironment::Close()
 
     fDbEnvInit = false;
 
-    for (auto& db : mapDb) {
+    for (auto& db : m_databases) {
         auto count = mapFileUseCount.find(db.first);
         assert(count == mapFileUseCount.end() || count->second == 0);
-        if (db.second) {
-            db.second->close(0);
-            delete db.second;
-            db.second = nullptr;
+        BerkeleyDatabase& database = db.second.get();
+        if (database.m_db) {
+            database.m_db->close(0);
+            database.m_db.reset();
         }
     }
 
@@ -480,7 +480,7 @@ BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bo
         if (!env->Open(false /* retry */))
             throw std::runtime_error("BerkeleyBatch: Failed to open database environment.");
 
-        pdb = env->mapDb[strFilename];
+        pdb = database.m_db.get();
         if (pdb == nullptr) {
             int ret;
             std::unique_ptr<Db> pdb_temp = MakeUnique<Db>(env->dbenv.get(), 0);
@@ -525,7 +525,7 @@ BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bo
             }
 
             pdb = pdb_temp.release();
-            env->mapDb[strFilename] = pdb;
+            database.m_db.reset(pdb);
 
             if (fCreate && !Exists(std::string("version"))) {
                 bool fTmp = fReadOnly;
@@ -580,12 +580,13 @@ void BerkeleyEnvironment::CloseDb(const std::string& strFile)
 {
     {
         LOCK(cs_db);
-        if (mapDb[strFile] != nullptr) {
+        auto it = m_databases.find(strFile);
+        assert(it != m_databases.end());
+        BerkeleyDatabase& database = it->second.get();
+        if (database.m_db) {
             // Close the database handle
-            Db* pdb = mapDb[strFile];
-            pdb->close(0);
-            delete pdb;
-            mapDb[strFile] = nullptr;
+            database.m_db->close(0);
+            database.m_db.reset();
         }
     }
 }
@@ -603,7 +604,7 @@ void BerkeleyEnvironment::ReloadDbEnv()
     });
 
     std::vector<std::string> filenames;
-    for (auto it : mapDb) {
+    for (auto it : m_databases) {
         filenames.push_back(it.first);
     }
     // Close the individual Db's
diff --git a/src/wallet/db.h b/src/wallet/db.h
index 5ced4c59cf..dd549bc463 100644
--- a/src/wallet/db.h
+++ b/src/wallet/db.h
@@ -31,6 +31,8 @@ struct WalletDatabaseFileId {
     bool operator==(const WalletDatabaseFileId& rhs) const;
 };
 
+class BerkeleyDatabase;
+
 class BerkeleyEnvironment
 {
 private:
@@ -43,7 +45,7 @@ private:
 public:
     std::unique_ptr<DbEnv> dbenv;
     std::map<std::string, int> mapFileUseCount;
-    std::map<std::string, Db*> mapDb;
+    std::map<std::string, std::reference_wrapper<BerkeleyDatabase>> m_databases;
     std::unordered_map<std::string, WalletDatabaseFileId> m_fileids;
     std::condition_variable_any m_db_in_use;
 
@@ -118,6 +120,8 @@ public:
         nUpdateCounter(0), nLastSeen(0), nLastFlushed(0), nLastWalletUpdate(0)
     {
         env = GetWalletEnv(wallet_path, strFile);
+        auto inserted = env->m_databases.emplace(strFile, std::ref(*this));
+        assert(inserted.second);
         if (mock) {
             env->Close();
             env->Reset();
@@ -125,6 +129,13 @@ public:
         }
     }
 
+    ~BerkeleyDatabase() {
+        if (env) {
+            size_t erased = env->m_databases.erase(strFile);
+            assert(erased == 1);
+        }
+    }
+
     /** Return object for accessing database at specified path. */
     static std::unique_ptr<BerkeleyDatabase> Create(const fs::path& path)
     {
@@ -164,6 +175,9 @@ public:
     unsigned int nLastFlushed;
     int64_t nLastWalletUpdate;
 
+    /** Database pointer. This is initialized lazily and reset during flushes, so it can be null. */
+    std::unique_ptr<Db> m_db;
+
 private:
     /** BerkeleyDB specific */
     BerkeleyEnvironment *env;