From 46372534cd63cb2c294b4938aed43174c7501ac1 Mon Sep 17 00:00:00 2001
From: Martin Kronbichler <kronbichler@lnm.mw.tum.de>
Date: Wed, 16 Oct 2013 14:43:54 +0000
Subject: [PATCH] Add update_ghost_values and compress to parallel block vector
 for a consistent interface with the parallel non-block vector.

git-svn-id: https://svn.dealii.org/trunk@31260 0785d39b-7218-0410-832d-ea1e28bc413d
---
 .../deal.II/lac/parallel_block_vector.h       | 58 +++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/deal.II/include/deal.II/lac/parallel_block_vector.h b/deal.II/include/deal.II/lac/parallel_block_vector.h
index 747d12a33e..3be362a635 100644
--- a/deal.II/include/deal.II/lac/parallel_block_vector.h
+++ b/deal.II/include/deal.II/lac/parallel_block_vector.h
@@ -226,6 +226,41 @@ namespace parallel
       void reinit (const BlockVector<Number2> &V,
                    const bool                 fast=false);
 
+      /**
+       * This function copies the data that has accumulated in the data buffer
+       * for ghost indices to the owning processor. For the meaning of the
+       * argument @p operation, see the entry on @ref GlossCompress
+       * "Compressing distributed vectors and matrices" in the glossary.
+       *
+       * There are two variants for this function. If called with argument @p
+       * VectorOperation::add adds all the data accumulated in ghost elements
+       * to the respective elements on the owning processor and clears the
+       * ghost array afterwards. If called with argument @p
+       * VectorOperation::insert, a set operation is performed. Since setting
+       * elements in a vector with ghost elements is ambiguous (as one can set
+       * both the element on the ghost site as well as the owning site), this
+       * operation makes the assumption that all data is set correctly on the
+       * owning processor. Upon call of compress(VectorOperation::insert), all
+       * ghost entries are therefore simply zeroed out (using
+       * zero_ghost_values()). In debug mode, a check is performed that makes
+       * sure that the data set is actually consistent between processors,
+       * i.e., whenever a non-zero ghost element is found, it is compared to
+       * the value on the owning processor and an exception is thrown if these
+       * elements do not agree.
+       *
+       */
+      void compress (::dealii::VectorOperation::values operation);
+
+      /**
+       * Fills the data field for ghost indices with the values stored in the
+       * respective positions of the owning processor. This function is needed
+       * before reading from ghosts. The function is @p const even though
+       * ghost data is changed. This is needed to allow functions with a @p
+       * const vector to perform the data exchange without creating
+       * temporaries.
+       */
+      void update_ghost_values () const;
+
       /**
        * Return whether the vector contains only elements with value
        * zero. This function is mainly for internal consistency checks and
@@ -543,6 +578,29 @@ namespace parallel
     }
 
 
+
+    template <typename Number>
+    inline
+    void
+    BlockVector<Number>::compress (::dealii::VectorOperation::values operation)
+    {
+      for (unsigned int block=0; block<this->n_blocks(); ++block)
+        this->block(block).compress(operation);
+    }
+
+
+
+    template <typename Number>
+    inline
+    void
+    BlockVector<Number>::update_ghost_values () const
+    {
+      for (unsigned int block=0; block<this->n_blocks(); ++block)
+        this->block(block).update_ghost_values();
+    }
+
+
+
     template <typename Number>
     inline
     bool
-- 
2.39.5