swtich singleton to thread safe version

Author: ziollek

src/collection/backend/lmdb.cc

@@ -42,9 +42,8 @@ LMDB::LMDB(std::string name) :
 
 int LMDB::txn_begin(unsigned int flags, MDB_txn **ret) {
     if (!isOpen) {
-        MDBEnvProvider* provider = MDBEnvProvider::GetInstance();
-        m_env = provider->GetEnv();
-        m_dbi = *(provider->GetDBI());
+        m_env = MDBEnvProvider::GetInstance().GetEnv();
+        m_dbi = *(MDBEnvProvider::GetInstance().GetDBI());
         isOpen = true;
     }
     return mdb_txn_begin(m_env, NULL, flags, ret);
@@ -502,22 +501,6 @@ void LMDB::resolveRegularExpression(const std::string& var,
 }
 
 
-MDBEnvProvider* MDBEnvProvider::provider_ = nullptr;
-
-MDBEnvProvider* MDBEnvProvider::GetInstance() {
-    if (provider_==nullptr) {
-        provider_ = new MDBEnvProvider();
-    }
-    return provider_;
-}
-
-void MDBEnvProvider::Finalize() {
-    if (provider_!=nullptr) {
-        provider_->close();
-        provider_ = nullptr;
-    }
-}
-
 MDBEnvProvider::MDBEnvProvider() :
     m_env(NULL), initialized(false) {
     pthread_mutex_init(&m_lock, NULL);

src/collection/backend/lmdb.h

@@ -66,9 +66,7 @@ namespace backend {
  *   "Use an MDB_env* in the process which opened it, without fork()ing."
  */
 class MDBEnvProvider {
- protected:
-    static MDBEnvProvider* provider_;
-    MDBEnvProvider();
+
  public:
     MDBEnvProvider(MDBEnvProvider &other) = delete;
     void operator=(const MDBEnvProvider &) = delete;
@@ -77,11 +75,12 @@ class MDBEnvProvider {
      * This is the static method that controls the access to the singleton
      * instance. On the first run, it creates a singleton object and places it
      * into the static field. On subsequent runs, it returns the client existing
-     * object stored in the static field.
+     * object stored in the static field (Meyers Singleton implementation).
      */
-    static MDBEnvProvider* GetInstance();
-    static void Finalize();
-
+    static MDBEnvProvider& GetInstance() {
+        static MDBEnvProvider instance;
+        return instance;
+    }
     MDB_env* GetEnv();
     MDB_dbi* GetDBI();
 
@@ -90,6 +89,7 @@ class MDBEnvProvider {
     MDB_dbi m_dbi;
     pthread_mutex_t m_lock;
 
+    MDBEnvProvider();
     bool initialized;
     void init();
     void close();

src/modsecurity.cc

@@ -106,9 +106,6 @@ ModSecurity::~ModSecurity() {
     delete m_ip_collection;
     delete m_session_collection;
     delete m_user_collection;
-#ifdef WITH_LMDB
-    collection::backend::MDBEnvProvider::Finalize();
-#endif
 }
 
 

test/cppcheck_suppressions.txt

@@ -44,14 +44,14 @@ functionStatic:src/engine/lua.h:71
 functionConst:src/utils/geo_lookup.h:49
 useInitializationList:src/operators/rbl.h:69
 constStatement:test/common/modsecurity_test.cc:82
-danglingTemporaryLifetime:src/modsecurity.cc:209
+danglingTemporaryLifetime:src/modsecurity.cc:206
 functionStatic:src/operators/geo_lookup.h:35
 duplicateBreak:src/operators/validate_utf8_encoding.cc
 duplicateBranch:src/request_body_processor/multipart.cc:91
 syntaxError:src/transaction.cc:62
 noConstructor:src/variables/variable.h:152
 duplicateBranch:src/request_body_processor/multipart.cc:93
-danglingTempReference:src/modsecurity.cc:209
+danglingTempReference:src/modsecurity.cc:206
 knownConditionTrueFalse:src/operators/validate_url_encoding.cc:77
 knownConditionTrueFalse:src/operators/verify_svnr.cc:87
 rethrowNoCurrentException:headers/modsecurity/transaction.h:307