Encapsulate BDB environment inside new CDBEnv class

Cleans up and organizes several scattered functions and variables related to
the BDB env.  Class CDBInit() existed to provide a
guaranteed-via-C++-destructor cleanup of the db environment.

A formal CDBEnv class provides all of this inside a single wrapper.

src/db.cpp

@@ -26,14 +26,11 @@ unsigned int nWalletDBUpdated;
 // CDB
 //
 
-CCriticalSection cs_db;
-static bool fDbEnvInit = false;
-bool fDetachDB = false;
-DbEnv dbenv(0);
+CDBEnv bitdb;
 map<string, int> mapFileUseCount;
 static map<string, Db*> mapDb;
 
-static void EnvShutdown()
+void CDBEnv::EnvShutdown()
 {
     if (!fDbEnvInit)
         return;
@@ -50,39 +47,30 @@ static void EnvShutdown()
     DbEnv(0).remove(GetDataDir().string().c_str(), 0);
 }
 
-class CDBInit
+CDBEnv::CDBEnv() : dbenv(0)
 {
-public:
-    CDBInit()
-    {
-    }
-    ~CDBInit()
-    {
-        EnvShutdown();
-    }
 }
-instance_of_cdbinit;
 
+CDBEnv::~CDBEnv()
+{
+    EnvShutdown();
+}
 
-CDB::CDB(const char *pszFile, const char* pszMode) : pdb(NULL)
+void CDBEnv::Close()
 {
-    int ret;
-    if (pszFile == NULL)
-        return;
+    EnvShutdown();
+}
 
-    fReadOnly = (!strchr(pszMode, '+') && !strchr(pszMode, 'w'));
-    bool fCreate = strchr(pszMode, 'c');
-    unsigned int nFlags = DB_THREAD;
-    if (fCreate)
-        nFlags |= DB_CREATE;
+bool CDBEnv::Open(boost::filesystem::path pathEnv_)
+{
+    if (fDbEnvInit)
+        return true;
 
-    {
-        LOCK(cs_db);
-        if (!fDbEnvInit)
-        {
     if (fShutdown)
-                return;
-            filesystem::path pathDataDir = GetDataDir();
+        return false;
+
+    pathEnv = pathEnv_;
+    filesystem::path pathDataDir = pathEnv;
     filesystem::path pathLogDir = pathDataDir / "database";
     filesystem::create_directory(pathLogDir);
     filesystem::path pathErrorFile = pathDataDir / "db.log";
@@ -96,10 +84,10 @@ CDB::CDB(const char *pszFile, const char* pszMode) : pdb(NULL)
     dbenv.set_lk_max_locks(10000);
     dbenv.set_lk_max_objects(10000);
     dbenv.set_errfile(fopen(pathErrorFile.string().c_str(), "a")); /// debug
-            dbenv.set_flags(DB_TXN_WRITE_NOSYNC, 1);
     dbenv.set_flags(DB_AUTO_COMMIT, 1);
+    dbenv.set_flags(DB_TXN_WRITE_NOSYNC, 1);
     dbenv.log_set_config(DB_LOG_AUTO_REMOVE, 1);
-            ret = dbenv.open(pathDataDir.string().c_str(),
+    int ret = dbenv.open(pathDataDir.string().c_str(),
                      DB_CREATE     |
                      DB_INIT_LOCK  |
                      DB_INIT_LOG   |
@@ -109,16 +97,42 @@ CDB::CDB(const char *pszFile, const char* pszMode) : pdb(NULL)
                      DB_RECOVER,
                      S_IRUSR | S_IWUSR);
     if (ret > 0)
-                throw runtime_error(strprintf("CDB() : error %d opening database environment", ret));
+        return error("CDB() : error %d opening database environment", ret);
+
     fDbEnvInit = true;
-        }
+    return true;
+}
+
+void CDBEnv::CheckpointLSN(std::string strFile)
+{
+    dbenv.txn_checkpoint(0, 0, 0);
+    dbenv.lsn_reset(strFile.c_str(), 0);
+}
+
+
+CDB::CDB(const char *pszFile, const char* pszMode) : pdb(NULL)
+{
+    int ret;
+    if (pszFile == NULL)
+        return;
+
+    fReadOnly = (!strchr(pszMode, '+') && !strchr(pszMode, 'w'));
+    bool fCreate = strchr(pszMode, 'c');
+    unsigned int nFlags = DB_THREAD;
+    if (fCreate)
+        nFlags |= DB_CREATE;
+
+    {
+        LOCK(bitdb.cs_db);
+        if (!bitdb.Open(GetDataDir()))
+            throw runtime_error("env open failed");
 
         strFile = pszFile;
         ++mapFileUseCount[strFile];
         pdb = mapDb[strFile];
         if (pdb == NULL)
         {
-            pdb = new Db(&dbenv, 0);
+            pdb = new Db(&bitdb.dbenv, 0);
 
             ret = pdb->open(NULL,      // Txn pointer
                             pszFile,   // Filename
@@ -132,7 +146,7 @@ CDB::CDB(const char *pszFile, const char* pszMode) : pdb(NULL)
                 delete pdb;
                 pdb = NULL;
                 {
-                     LOCK(cs_db);
+                     LOCK(bitdb.cs_db);
                     --mapFileUseCount[strFile];
                 }
                 strFile = "";
@@ -170,10 +184,10 @@ void CDB::Close()
     if (strFile == "blkindex.dat" && IsInitialBlockDownload())
         nMinutes = 5;
 
-    dbenv.txn_checkpoint(nMinutes ? GetArg("-dblogsize", 100)*1024 : 0, nMinutes, 0);
+    bitdb.dbenv.txn_checkpoint(nMinutes ? GetArg("-dblogsize", 100)*1024 : 0, nMinutes, 0);
 
     {
-        LOCK(cs_db);
+        LOCK(bitdb.cs_db);
         --mapFileUseCount[strFile];
     }
 }
@@ -181,7 +195,7 @@ void CDB::Close()
 void CloseDb(const string& strFile)
 {
     {
-        LOCK(cs_db);
+        LOCK(bitdb.cs_db);
         if (mapDb[strFile] != NULL)
         {
             // Close the database handle
@@ -198,13 +212,12 @@ bool CDB::Rewrite(const string& strFile, const char* pszSkip)
     while (!fShutdown)
     {
         {
-            LOCK(cs_db);
+            LOCK(bitdb.cs_db);
             if (!mapFileUseCount.count(strFile) || mapFileUseCount[strFile] == 0)
             {
                 // Flush log data to the dat file
                 CloseDb(strFile);
-                dbenv.txn_checkpoint(0, 0, 0);
-                dbenv.lsn_reset(strFile.c_str(), 0);
+                bitdb.CheckpointLSN(strFile);
                 mapFileUseCount.erase(strFile);
 
                 bool fSuccess = true;
@@ -212,7 +225,7 @@ bool CDB::Rewrite(const string& strFile, const char* pszSkip)
                 string strFileRes = strFile + ".rewrite";
                 { // surround usage of db with extra {}
                     CDB db(strFile.c_str(), "r");
-                    Db* pdbCopy = new Db(&dbenv, 0);
+                    Db* pdbCopy = new Db(&bitdb.dbenv, 0);
     
                     int ret = pdbCopy->open(NULL,                 // Txn pointer
                                             strFileRes.c_str(),   // Filename
@@ -270,10 +283,10 @@ bool CDB::Rewrite(const string& strFile, const char* pszSkip)
                 }
                 if (fSuccess)
                 {
-                    Db dbA(&dbenv, 0);
+                    Db dbA(&bitdb.dbenv, 0);
                     if (dbA.remove(strFile.c_str(), NULL, 0))
                         fSuccess = false;
-                    Db dbB(&dbenv, 0);
+                    Db dbB(&bitdb.dbenv, 0);
                     if (dbB.rename(strFileRes.c_str(), NULL, strFile.c_str(), 0))
                         fSuccess = false;
                 }
@@ -288,12 +301,12 @@ bool CDB::Rewrite(const string& strFile, const char* pszSkip)
 }
 
 
-void DBFlush(bool fShutdown)
+void CDBEnv::Flush(bool fShutdown)
 {
     int64 nStart = GetTimeMillis();
     // Flush log data to the actual data file
     //  on all files that are not in use
-    printf("DBFlush(%s)%s\n", fShutdown ? "true" : "false", fDbEnvInit ? "" : " db not started");
+    printf("Flush(%s)%s\n", fShutdown ? "true" : "false", fDbEnvInit ? "" : " db not started");
     if (!fDbEnvInit)
         return;
     {
@@ -327,7 +340,7 @@ void DBFlush(bool fShutdown)
             if (mapFileUseCount.empty())
             {
                 dbenv.log_archive(&listp, DB_ARCH_REMOVE);
-                EnvShutdown();
+                Close();
             }
         }
     }

src/db.h

@@ -25,14 +25,36 @@ class CWallet;
 class CWalletTx;
 
 extern unsigned int nWalletDBUpdated;
-extern bool fDetachDB;
-extern DbEnv dbenv;
 
-extern void DBFlush(bool fShutdown);
 void ThreadFlushWalletDB(void* parg);
 bool BackupWallet(const CWallet& wallet, const std::string& strDest);
 
 
+class CDBEnv
+{
+private:
+    bool fDetachDB;
+    bool fDbEnvInit;
+    boost::filesystem::path pathEnv;
+
+    void EnvShutdown();
+
+public:
+    mutable CCriticalSection cs_db;
+    DbEnv dbenv;
+
+    CDBEnv();
+    ~CDBEnv();
+    bool Open(boost::filesystem::path pathEnv_);
+    void Close();
+    void Flush(bool fShutdown);
+    void CheckpointLSN(std::string strFile);
+    void SetDetach(bool fDetachDB_) { fDetachDB = fDetachDB_; }
+};
+
+extern CDBEnv bitdb;
+
+
 /** RAII class that provides access to a Berkeley database */
 class CDB
 {
@@ -216,7 +238,7 @@ public:
         if (!pdb)
             return false;
         DbTxn* ptxn = NULL;
-        int ret = dbenv.txn_begin(GetTxn(), &ptxn, DB_TXN_WRITE_NOSYNC);
+        int ret = bitdb.dbenv.txn_begin(GetTxn(), &ptxn, DB_TXN_WRITE_NOSYNC);
         if (!ptxn || ret != 0)
             return false;
         vTxn.push_back(ptxn);

src/init.cpp

@@ -54,9 +54,9 @@ void Shutdown(void* parg)
     {
         fShutdown = true;
         nTransactionsUpdated++;
-        DBFlush(false);
+        bitdb.Flush(false);
         StopNode();
-        DBFlush(true);
+        bitdb.Flush(true);
         boost::filesystem::remove(GetPidFile());
         UnregisterWallet(pwalletMain);
         delete pwalletMain;
@@ -294,7 +294,7 @@ bool AppInit2()
     }
 
     fDebug = GetBoolArg("-debug");
-    fDetachDB = GetBoolArg("-detachdb", false);
+    bitdb.SetDetach(GetBoolArg("-detachdb", false));
 
 #if !defined(WIN32) && !defined(QT_GUI)
     fDaemon = GetBoolArg("-daemon");

src/walletdb.cpp

@@ -13,7 +13,6 @@ using namespace boost;
 
 static uint64 nAccountingEntryNumber = 0;
 
-extern CCriticalSection cs_db;
 extern map<string, int> mapFileUseCount;
 extern void CloseDb(const string& strFile);
 
@@ -350,7 +349,7 @@ void ThreadFlushWalletDB(void* parg)
 
         if (nLastFlushed != nWalletDBUpdated && GetTime() - nLastWalletUpdate >= 2)
         {
-            TRY_LOCK(cs_db,lockDb);
+            TRY_LOCK(bitdb.cs_db,lockDb);
             if (lockDb)
             {
                 // Don't do this if any databases are in use
@@ -373,8 +372,7 @@ void ThreadFlushWalletDB(void* parg)
 
                         // Flush wallet.dat so it's self contained
                         CloseDb(strFile);
-                        dbenv.txn_checkpoint(0, 0, 0);
-                        dbenv.lsn_reset(strFile.c_str(), 0);
+                        bitdb.CheckpointLSN(strFile);
 
                         mapFileUseCount.erase(mi++);
                         printf("Flushed wallet.dat %"PRI64d"ms\n", GetTimeMillis() - nStart);
@@ -392,13 +390,12 @@ bool BackupWallet(const CWallet& wallet, const string& strDest)
     while (!fShutdown)
     {
         {
-            LOCK(cs_db);
+            LOCK(bitdb.cs_db);
             if (!mapFileUseCount.count(wallet.strWalletFile) || mapFileUseCount[wallet.strWalletFile] == 0)
             {
                 // Flush log data to the dat file
                 CloseDb(wallet.strWalletFile);
-                dbenv.txn_checkpoint(0, 0, 0);
-                dbenv.lsn_reset(wallet.strWalletFile.c_str(), 0);
+                bitdb.CheckpointLSN(wallet.strWalletFile);
                 mapFileUseCount.erase(wallet.strWalletFile);
 
                 // Copy wallet.dat