Optimise storage/retrieval of projPJ objects

Author: nyalldawson

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->destProjection() ) && ( direction == ReverseTransform ) )
-       || ( pj_is_latlong( d->sourceProjection() ) && ( 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->destProjection(), d->sourceProjection(), numPoints, 0, x, y, z );
+    projResult = pj_transform( destProj, sourceProj, numPoints, 0, x, y, z );
   }
   else
   {
-    Q_ASSERT( d->sourceProjection() );
-    Q_ASSERT( d->destProjection() );
-    projResult = pj_transform( d->sourceProjection(), d->destProjection(), 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->sourceProjection(), 0 );
-    char *dstdef = pj_get_def( d->destProjection(), 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->destProjection() ) && ( direction == ForwardTransform ) )
-       || ( pj_is_latlong( d->sourceProjection() ) && ( 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_p.cpp

@@ -135,14 +135,15 @@ bool QgsCoordinateTransformPrivate::initialize()
     addNullGridShifts( mSourceProjString, mDestProjString );
   }
 
-  initializeCurrentContext();
+  // create proj projections for current thread
+  QPair<projPJ, projPJ> res = threadLocalProjData();
 
 #ifdef COORDINATE_TRANSFORM_VERBOSE
   QgsDebugMsg( "From proj : " + mSourceCRS.toProj4() );
   QgsDebugMsg( "To proj   : " + mDestCRS.toProj4() );
 #endif
 
-  if ( !destProjection() || !sourceProjection() )
+  if ( !res.first || !res.second )
   {
     mIsValid = false;
   }
@@ -188,42 +189,26 @@ bool QgsCoordinateTransformPrivate::initialize()
   return mIsValid;
 }
 
-void QgsCoordinateTransformPrivate::initializeCurrentContext()
-{
-  mProjLock.lockForWrite();
-  mProjProjections.insert( reinterpret_cast< uintptr_t>( mProjContext.get() ), qMakePair( pj_init_plus_ctx( mProjContext.get(), mSourceProjString.toUtf8() ),
-                           pj_init_plus_ctx( mProjContext.get(), mDestProjString.toUtf8() ) ) );
-  mProjLock.unlock();
-}
-
-projPJ QgsCoordinateTransformPrivate::sourceProjection()
+QPair<projPJ, projPJ> QgsCoordinateTransformPrivate::threadLocalProjData()
 {
   mProjLock.lockForRead();
-  if ( mProjProjections.contains( reinterpret_cast< uintptr_t>( mProjContext.get() ) ) )
-  {
-    projPJ src = mProjProjections.value( reinterpret_cast< uintptr_t>( mProjContext.get() ) ).first;
-    mProjLock.unlock();
-    return src;
-  }
-  mProjLock.unlock();
 
-  initializeCurrentContext();
-  return sourceProjection();
-}
-
-projPJ QgsCoordinateTransformPrivate::destProjection()
-{
-  mProjLock.lockForRead();
-  if ( mProjProjections.contains( reinterpret_cast< uintptr_t>( mProjContext.get() ) ) )
+  QMap < uintptr_t, QPair< projPJ, projPJ > >::const_iterator it = mProjProjections.constFind( reinterpret_cast< uintptr_t>( mProjContext.get() ) );
+  if ( it != mProjProjections.constEnd() )
   {
-    projPJ dest = mProjProjections.value( reinterpret_cast< uintptr_t>( mProjContext.get() ) ).second;
+    QPair<projPJ, projPJ> res = it.value();
     mProjLock.unlock();
-    return dest;
+    return res;
   }
-  mProjLock.unlock();
 
-  initializeCurrentContext();
-  return destProjection();
+  // proj projections don't exist yet, so we need to create
+  mProjLock.unlock();
+  mProjLock.lockForWrite();
+  QPair<projPJ, projPJ> res = qMakePair( pj_init_plus_ctx( mProjContext.get(), mSourceProjString.toUtf8() ),
+                                         pj_init_plus_ctx( mProjContext.get(), mDestProjString.toUtf8() ) );
+  mProjProjections.insert( reinterpret_cast< uintptr_t>( mProjContext.get() ), res );
+  mProjLock.unlock();
+  return res;
 }
 
 QString QgsCoordinateTransformPrivate::stripDatumTransform( const QString &proj4 ) const

src/core/qgscoordinatetransform_p.h

@@ -67,7 +67,8 @@ class QgsCoordinateTransformPrivate : public QSharedData
     ~QgsCoordinateTransformPrivate();
 
     bool initialize();
-    void initializeCurrentContext();
+
+    QPair< projPJ, projPJ > threadLocalProjData();
 
     //! Flag to indicate whether the transform is valid (ie has a valid
     //! source and destination crs)
@@ -87,8 +88,6 @@ class QgsCoordinateTransformPrivate : public QSharedData
 
     QString mSourceProjString;
     QString mDestProjString;
-    projPJ sourceProjection();
-    projPJ destProjection();
 
     int mSourceDatumTransform;
     int mDestinationDatumTransform;