Merge pull request #4561 from nyalldawson/proj_thread2

Avoid using thread unsafe proj API - approach 2

Author: nyalldawson

src/app/qgscustomprojectiondialog.cpp

@@ -453,8 +453,8 @@ void QgsCustomProjectionDialog::on_pbnCalculate_clicked()
   //
   // We must check the prj def is valid!
   //
-
-  projPJ myProj = pj_init_plus( teParameters->toPlainText().toLocal8Bit().data() );
+  projCtx pContext = pj_ctx_alloc();
+  projPJ myProj = pj_init_plus_ctx( pContext, teParameters->toPlainText().toLocal8Bit().data() );
 
   QgsDebugMsg( QString( "My proj: %1" ).arg( teParameters->toPlainText() ) );
 
@@ -465,6 +465,7 @@ void QgsCustomProjectionDialog::on_pbnCalculate_clicked()
     projectedX->setText( QLatin1String( "" ) );
     projectedY->setText( QLatin1String( "" ) );
     pj_free( myProj );
+    pj_ctx_free( pContext );
     return;
 
   }
@@ -480,10 +481,11 @@ void QgsCustomProjectionDialog::on_pbnCalculate_clicked()
     projectedX->setText( QLatin1String( "" ) );
     projectedY->setText( QLatin1String( "" ) );
     pj_free( myProj );
+    pj_ctx_free( pContext );
     return;
   }
 
-  projPJ wgs84Proj = pj_init_plus( GEOPROJ4.toLocal8Bit().data() ); //defined in qgis.h
+  projPJ wgs84Proj = pj_init_plus_ctx( pContext, GEOPROJ4.toLocal8Bit().data() ); //defined in qgis.h
 
   if ( !wgs84Proj )
   {
@@ -492,6 +494,7 @@ void QgsCustomProjectionDialog::on_pbnCalculate_clicked()
     projectedX->setText( QLatin1String( "" ) );
     projectedY->setText( QLatin1String( "" ) );
     pj_free( wgs84Proj );
+    pj_ctx_free( pContext );
     return;
   }
 
@@ -517,6 +520,7 @@ void QgsCustomProjectionDialog::on_pbnCalculate_clicked()
   //
   pj_free( myProj );
   pj_free( wgs84Proj );
+  pj_ctx_free( pContext );
 
 }
 

src/core/CMakeLists.txt

@@ -128,6 +128,7 @@ SET(QGIS_CORE_SRCS
   qgscontexthelp.cpp
   qgscoordinatereferencesystem.cpp
   qgscoordinatetransform.cpp
+  qgscoordinatetransform_p.cpp
   qgscoordinateutils.cpp
   qgscredentials.cpp
   qgscrscache.cpp

src/core/qgscoordinatereferencesystem.cpp

@@ -1099,16 +1099,18 @@ void QgsCoordinateReferenceSystem::setProj4String( const QString &proj4String )
   // e.g if they lack a +ellps parameter, it will automatically add +ellps=WGS84, but as
   // we use the original mProj4 with QgsCoordinateTransform, it will fail to initialize
   // so better detect it now.
-  projPJ proj = pj_init_plus( proj4String.trimmed().toLatin1().constData() );
+  projCtx pContext = pj_ctx_alloc();
+  projPJ proj = pj_init_plus_ctx( pContext, proj4String.trimmed().toLatin1().constData() );
   if ( !proj )
   {
-    QgsDebugMsgLevel( "proj.4 string rejected by pj_init_plus()", 4 );
+    QgsDebugMsgLevel( "proj.4 string rejected by pj_init_plus_ctx()", 4 );
     d->mIsValid = false;
   }
   else
   {
     pj_free( proj );
   }
+  pj_ctx_free( pContext );
   d->mWkt.clear();
   setMapUnits();
 }
@@ -2020,6 +2022,8 @@ int QgsCoordinateReferenceSystem::syncDatabase()
                sqlite3_errmsg( database ) );
   }
 
+  projCtx pContext = pj_ctx_alloc();
+
 #if !defined(PJ_VERSION) || PJ_VERSION!=470
   sql = QStringLiteral( "select auth_name,auth_id,parameters from tbl_srs WHERE auth_name<>'EPSG' AND NOT deprecated AND NOT noupdate" );
   if ( sqlite3_prepare( database, sql.toLatin1(), sql.size(), &select, &tail ) == SQLITE_OK )
@@ -2031,11 +2035,11 @@ int QgsCoordinateReferenceSystem::syncDatabase()
       const char *params    = reinterpret_cast< const char * >( sqlite3_column_text( select, 2 ) );
 
       QString input = QStringLiteral( "+init=%1:%2" ).arg( QString( auth_name ).toLower(), auth_id );
-      projPJ pj = pj_init_plus( input.toLatin1() );
+      projPJ pj = pj_init_plus_ctx( pContext, input.toLatin1() );
       if ( !pj )
       {
         input = QStringLiteral( "+init=%1:%2" ).arg( QString( auth_name ).toUpper(), auth_id );
-        pj = pj_init_plus( input.toLatin1() );
+        pj = pj_init_plus_ctx( pContext, input.toLatin1() );
       }
 
       if ( pj )
@@ -2099,6 +2103,7 @@ int QgsCoordinateReferenceSystem::syncDatabase()
   sqlite3_finalize( select );
 #endif
 
+  pj_ctx_free( pContext );
 
   if ( sqlite3_exec( database, "COMMIT", nullptr, nullptr, nullptr ) != SQLITE_OK )
   {

src/core/qgscoordinatetransform.cpp

@@ -474,8 +474,12 @@ void QgsCoordinateTransform::transformCoords( int numPoints, double *x, double *
 
   // if the source/destination projection is lat/long, convert the points to radians
   // prior to transforming
-  if ( ( pj_is_latlong( d->mDestinationProjection ) && ( direction == ReverseTransform ) )
-       || ( pj_is_latlong( d->mSourceProjection ) && ( direction == ForwardTransform ) ) )
+  QPair<projPJ, projPJ> projData = d->threadLocalProjData();
+  projPJ sourceProj = projData.first;
+  projPJ destProj = projData.second;
+
+  if ( ( pj_is_latlong( destProj ) && ( direction == ReverseTransform ) )
+       || ( pj_is_latlong( sourceProj ) && ( direction == ForwardTransform ) ) )
   {
     for ( int i = 0; i < numPoints; ++i )
     {
@@ -487,13 +491,13 @@ void QgsCoordinateTransform::transformCoords( int numPoints, double *x, double *
   int projResult;
   if ( direction == ReverseTransform )
   {
-    projResult = pj_transform( d->mDestinationProjection, d->mSourceProjection, numPoints, 0, x, y, z );
+    projResult = pj_transform( destProj, sourceProj, numPoints, 0, x, y, z );
   }
   else
   {
-    Q_ASSERT( d->mSourceProjection );
-    Q_ASSERT( d->mDestinationProjection );
-    projResult = pj_transform( d->mSourceProjection, d->mDestinationProjection, numPoints, 0, x, y, z );
+    Q_ASSERT( sourceProj );
+    Q_ASSERT( destProj );
+    projResult = pj_transform( sourceProj, destProj, numPoints, 0, x, y, z );
   }
 
   if ( projResult != 0 )
@@ -515,8 +519,8 @@ void QgsCoordinateTransform::transformCoords( int numPoints, double *x, double *
 
     QString dir = ( direction == ForwardTransform ) ? QObject::tr( "forward transform" ) : QObject::tr( "inverse transform" );
 
-    char *srcdef = pj_get_def( d->mSourceProjection, 0 );
-    char *dstdef = pj_get_def( d->mDestinationProjection, 0 );
+    char *srcdef = pj_get_def( sourceProj, 0 );
+    char *dstdef = pj_get_def( destProj, 0 );
 
     QString msg = QObject::tr( "%1 of\n"
                                "%2"
@@ -538,8 +542,8 @@ void QgsCoordinateTransform::transformCoords( int numPoints, double *x, double *
 
   // if the result is lat/long, convert the results from radians back
   // to degrees
-  if ( ( pj_is_latlong( d->mDestinationProjection ) && ( direction == ForwardTransform ) )
-       || ( pj_is_latlong( d->mSourceProjection ) && ( direction == ReverseTransform ) ) )
+  if ( ( pj_is_latlong( destProj ) && ( direction == ForwardTransform ) )
+       || ( pj_is_latlong( sourceProj ) && ( direction == ReverseTransform ) ) )
   {
     for ( int i = 0; i < numPoints; ++i )
     {

src/core/qgscoordinatetransform.h

@@ -280,7 +280,7 @@ class CORE_EXPORT QgsCoordinateTransform
 
     static void searchDatumTransform( const QString &sql, QList< int > &transforms );
 
-    QExplicitlySharedDataPointer<QgsCoordinateTransformPrivate> d;
+    mutable QExplicitlySharedDataPointer<QgsCoordinateTransformPrivate> d;
 };
 
 //! Output stream operator