make initialization of connection pool thread save on MSVC

(probably better fix for 1e96813)

src/providers/ogr/qgsogrconnpool.cpp

@@ -15,10 +15,10 @@
 
 #include "qgsogrconnpool.h"
 
+QgsOgrConnPool QgsOgrConnPool::sInstance;
 
 QgsOgrConnPool* QgsOgrConnPool::instance()
 {
-  static QgsOgrConnPool sInstance;
   return &sInstance;
 }
 

src/providers/ogr/qgsogrconnpool.h

@@ -85,6 +85,8 @@ class QgsOgrConnPool : public QgsConnectionPool<QgsOgrConn*, QgsOgrConnPoolGroup
   private:
     QgsOgrConnPool();
     ~QgsOgrConnPool();
+
+    static QgsOgrConnPool sInstance;
 };
 
 

src/providers/postgres/qgspostgresconnpool.cpp

@@ -16,21 +16,11 @@
 #include "qgspostgresconnpool.h"
 #include "qgspostgresconn.h"
 
+QgsPostgresConnPool QgsPostgresConnPool::sInstance;
 
 QgsPostgresConnPool* QgsPostgresConnPool::instance()
 {
-  static QgsPostgresConnPool *sInstance = 0;
-
-  if ( !sInstance )
-  {
-    static QMutex m;
-    m.lock();
-    if ( !sInstance )
-      sInstance = new QgsPostgresConnPool();
-    m.unlock();
-  }
-
-  return sInstance;
+  return &sInstance;
 }
 
 QgsPostgresConnPool::QgsPostgresConnPool() : QgsConnectionPool<QgsPostgresConn*, QgsPostgresConnPoolGroup>()

src/providers/postgres/qgspostgresconnpool.h

@@ -17,7 +17,6 @@
 #define QGSPOSTGRESCONNPOOL_H
 
 #include "qgsconnectionpool.h"
-
 #include "qgspostgresconn.h"
 
 
@@ -77,6 +76,8 @@ class QgsPostgresConnPool : public QgsConnectionPool<QgsPostgresConn*, QgsPostgr
   private:
     QgsPostgresConnPool();
     ~QgsPostgresConnPool();
+
+    static QgsPostgresConnPool sInstance;
 };
 
 

src/providers/spatialite/qgsspatialiteconnpool.cpp

@@ -15,9 +15,9 @@
 
 #include "qgsspatialiteconnpool.h"
 
+QgsSpatiaLiteConnPool QgsSpatiaLiteConnPool::sInstance;
 
 QgsSpatiaLiteConnPool* QgsSpatiaLiteConnPool::instance()
 {
-  static QgsSpatiaLiteConnPool sInstance;
   return &sInstance;
 }

src/providers/spatialite/qgsspatialiteconnpool.h

@@ -17,7 +17,6 @@
 #define QGSSPATIALITECONPOOL_H
 
 #include "qgsconnectionpool.h"
-
 #include "qgsspatialiteconnection.h"
 
 inline QString qgsConnectionPool_ConnectionToName( QgsSqliteHandle* c )
@@ -67,9 +66,9 @@ class QgsSpatiaLiteConnPoolGroup : public QObject, public QgsConnectionPoolGroup
 /** SpatiaLite connection pool - singleton */
 class QgsSpatiaLiteConnPool : public QgsConnectionPool<QgsSqliteHandle*, QgsSpatiaLiteConnPoolGroup>
 {
+    static QgsSpatiaLiteConnPool sInstance;
   public:
     static QgsSpatiaLiteConnPool* instance();
-
 };