From d86efab37002841fd059251672e1ec1a977b743f Mon Sep 17 00:00:00 2001
From: Andrew Chow <achow101-github@achow101.com>
Date: Sun, 10 May 2020 22:41:34 -0400
Subject: walletdb: Move Db->open to BerkeleyDatabase::Open

Instead of opening the Db handle in BerkeleyBatch, make BerkeleyDatabase
do that.
---
 src/wallet/bdb.cpp | 59 ++++++++++++++++++++++++++++--------------------------
 src/wallet/bdb.h   |  2 +-
 2 files changed, 32 insertions(+), 29 deletions(-)

diff --git a/src/wallet/bdb.cpp b/src/wallet/bdb.cpp
index 4653a75fce..55590fcc5e 100644
--- a/src/wallet/bdb.cpp
+++ b/src/wallet/bdb.cpp
@@ -317,13 +317,27 @@ BerkeleyDatabase::~BerkeleyDatabase()
 
 BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bool fFlushOnCloseIn) : pdb(nullptr), activeTxn(nullptr), m_cursor(nullptr), m_database(database)
 {
+    database.AddRef();
+    database.Open(pszMode);
     fReadOnly = (!strchr(pszMode, '+') && !strchr(pszMode, 'w'));
     fFlushOnClose = fFlushOnCloseIn;
     env = database.env.get();
-    if (database.IsDummy()) {
+    pdb = database.m_db.get();
+    strFile = database.strFile;
+    bool fCreate = strchr(pszMode, 'c') != nullptr;
+    if (fCreate && !Exists(std::string("version"))) {
+        bool fTmp = fReadOnly;
+        fReadOnly = false;
+        Write(std::string("version"), CLIENT_VERSION);
+        fReadOnly = fTmp;
+    }
+}
+
+void BerkeleyDatabase::Open(const char* pszMode)
+{
+    if (IsDummy()){
         return;
     }
-    const std::string &strFilename = database.strFile;
 
     bool fCreate = strchr(pszMode, 'c') != nullptr;
     unsigned int nFlags = DB_THREAD;
@@ -334,10 +348,9 @@ BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bo
         LOCK(cs_db);
         bilingual_str open_err;
         if (!env->Open(open_err))
-            throw std::runtime_error("BerkeleyBatch: Failed to open database environment.");
+            throw std::runtime_error("BerkeleyDatabase: Failed to open database environment.");
 
-        pdb = database.m_db.get();
-        if (pdb == nullptr) {
+        if (m_db == nullptr) {
             int ret;
             std::unique_ptr<Db> pdb_temp = MakeUnique<Db>(env->dbenv.get(), 0);
 
@@ -346,19 +359,19 @@ BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bo
                 DbMpoolFile* mpf = pdb_temp->get_mpf();
                 ret = mpf->set_flags(DB_MPOOL_NOFILE, 1);
                 if (ret != 0) {
-                    throw std::runtime_error(strprintf("BerkeleyBatch: Failed to configure for no temp file backing for database %s", strFilename));
+                    throw std::runtime_error(strprintf("BerkeleyDatabase: Failed to configure for no temp file backing for database %s", strFile));
                 }
             }
 
             ret = pdb_temp->open(nullptr,                             // Txn pointer
-                            fMockDb ? nullptr : strFilename.c_str(),  // Filename
-                            fMockDb ? strFilename.c_str() : "main",   // Logical db name
+                            fMockDb ? nullptr : strFile.c_str(),      // Filename
+                            fMockDb ? strFile.c_str() : "main",       // Logical db name
                             DB_BTREE,                                 // Database type
                             nFlags,                                   // Flags
                             0);
 
             if (ret != 0) {
-                throw std::runtime_error(strprintf("BerkeleyBatch: Error %d, can't open database %s", ret, strFilename));
+                throw std::runtime_error(strprintf("BerkeleyDatabase: Error %d, can't open database %s", ret, strFile));
             }
 
             // Call CheckUniqueFileid on the containing BDB environment to
@@ -377,29 +390,15 @@ BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bo
             // versions of BDB have an set_lk_exclusive method for this
             // purpose, but the older version we use does not.)
             for (const auto& env : g_dbenvs) {
-                CheckUniqueFileid(*env.second.lock().get(), strFilename, *pdb_temp, this->env->m_fileids[strFilename]);
+                CheckUniqueFileid(*env.second.lock().get(), strFile, *pdb_temp, this->env->m_fileids[strFile]);
             }
 
-            pdb = pdb_temp.release();
-            database.m_db.reset(pdb);
+            m_db.reset(pdb_temp.release());
 
-            if (fCreate && !Exists(std::string("version"))) {
-                bool fTmp = fReadOnly;
-                fReadOnly = false;
-                Write(std::string("version"), CLIENT_VERSION);
-                fReadOnly = fTmp;
-            }
         }
-        database.AddRef();
-        strFile = strFilename;
     }
 }
 
-void BerkeleyDatabase::Open(const char* mode)
-{
-    throw std::logic_error("BerkeleyDatabase does not implement Open. This function should not be called.");
-}
-
 void BerkeleyBatch::Flush()
 {
     if (activeTxn)
@@ -420,6 +419,12 @@ void BerkeleyDatabase::IncrementUpdateCounter()
     ++nUpdateCounter;
 }
 
+BerkeleyBatch::~BerkeleyBatch()
+{
+    Close();
+    m_database.RemoveRef();
+}
+
 void BerkeleyBatch::Close()
 {
     if (!pdb)
@@ -432,8 +437,6 @@ void BerkeleyBatch::Close()
 
     if (fFlushOnClose)
         Flush();
-
-    m_database.RemoveRef();
 }
 
 void BerkeleyEnvironment::CloseDb(const std::string& strFile)
@@ -844,7 +847,7 @@ void BerkeleyDatabase::RemoveRef()
 {
     LOCK(cs_db);
     m_refcount--;
-    env->m_db_in_use.notify_all();
+    if (env) env->m_db_in_use.notify_all();
 }
 
 std::unique_ptr<DatabaseBatch> BerkeleyDatabase::MakeBatch(const char* mode, bool flush_on_close)
diff --git a/src/wallet/bdb.h b/src/wallet/bdb.h
index 6c148b37cb..90f5f2e877 100644
--- a/src/wallet/bdb.h
+++ b/src/wallet/bdb.h
@@ -217,7 +217,7 @@ protected:
 
 public:
     explicit BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode = "r+", bool fFlushOnCloseIn=true);
-    ~BerkeleyBatch() override { Close(); }
+    ~BerkeleyBatch() override;
 
     BerkeleyBatch(const BerkeleyBatch&) = delete;
     BerkeleyBatch& operator=(const BerkeleyBatch&) = delete;
-- 
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