STYLE: communication name "buffered" instead of "blocking"

- "buffered" corresponds to MPI_Bsend (buffered send),
  whereas the old name "blocking" is misleading since the
  regular MPI_Send also blocks until completion
  (ie, buffer can be reused).

ENH: IPstream::read() returns std::streamsize instead of label (#3152)

- previously returned a 'label' but std::streamsize is consistent with
  the input parameter and will help with later adjustments.

- use <label> instead of <int> for internal accounting of the message
  size, for consistency with the underyling List<char> buffers used.

- improve handling for corner case of IPstream receive with
  non-blocking, although this combination is not used anywhere

applications/test/parallel-comm1/Test-parallel-comm1.C

@@ -62,7 +62,7 @@ scalar sumReduce
                 scalar procValue;
                 UIPstream::read
                 (
-                    UPstream::commsTypes::blocking,
+                    UPstream::commsTypes::buffered,
                     proci,
                     reinterpret_cast<char*>(&procValue),
                     sizeof(scalar),
@@ -79,7 +79,7 @@ scalar sumReduce
             {
                 UOPstream::write
                 (
-                    UPstream::commsTypes::blocking,
+                    UPstream::commsTypes::buffered,
                     proci,
                     reinterpret_cast<const char*>(&sum),
                     sizeof(scalar),
@@ -93,7 +93,7 @@ scalar sumReduce
             {
                 UOPstream::write
                 (
-                    UPstream::commsTypes::blocking,
+                    UPstream::commsTypes::buffered,
                     UPstream::masterNo(),
                     reinterpret_cast<const char*>(&localValue),
                     sizeof(scalar),
@@ -105,7 +105,7 @@ scalar sumReduce
             {
                 UIPstream::read
                 (
-                    UPstream::commsTypes::blocking,
+                    UPstream::commsTypes::buffered,
                     UPstream::masterNo(),
                     reinterpret_cast<char*>(&sum),
                     sizeof(scalar),

applications/test/parallel/Test-parallel.C

@@ -131,7 +131,7 @@ void testTransfer(const T& input)
         for (const int proci : UPstream::subProcs())
         {
             Perr<< "master sending to proc:" << proci << endl;
-            OPstream os(UPstream::commsTypes::blocking, proci);
+            OPstream os(UPstream::commsTypes::buffered, proci);
             os  << data;
         }
     }
@@ -139,7 +139,7 @@ void testTransfer(const T& input)
     {
         {
             Perr<< "proc sending to master" << endl;
-            OPstream os(UPstream::commsTypes::blocking, UPstream::masterNo());
+            OPstream os(UPstream::commsTypes::buffered, UPstream::masterNo());
             os  << data;
         }
 
@@ -169,7 +169,7 @@ void testTokenized(const T& data)
         for (const int proci : UPstream::subProcs())
         {
             Perr<< "master sending to proc:" << proci << endl;
-            OPstream os(UPstream::commsTypes::blocking, proci);
+            OPstream os(UPstream::commsTypes::buffered, proci);
             os  << tok;
         }
     }
@@ -177,7 +177,7 @@ void testTokenized(const T& data)
     {
         {
             Perr<< "proc sending to master" << endl;
-            OPstream os(UPstream::commsTypes::blocking, UPstream::masterNo());
+            OPstream os(UPstream::commsTypes::buffered, UPstream::masterNo());
             os  << tok;
         }
 

applications/test/surface-sampling/mydebugSurfaceWriter.H

@@ -44,7 +44,7 @@ Description
     Format options:
     \table
         Property    | Description                           | Required | Default
-        commsType   | blocking/nonBlocking/scheduled        | no  | scheduled
+        commsType   | scheduled/nonBlocking/buffered        | no  | scheduled
         merge       | Enable geometry/field merging         | no  | true
         write       | Write file(s)                         | no  | false
         narrow      | Communicate with narrowed values      | no  | false

applications/utilities/mesh/manipulation/createPatch/createPatch.C

@@ -568,10 +568,9 @@ void syncPoints
                     }
                 }
 
-                // buffered send
                 OPstream toNbr
                 (
-                    UPstream::commsTypes::blocking,
+                    UPstream::commsTypes::buffered,
                     procPatch.neighbProcNo()
                 );
                 toNbr << patchInfo;

applications/utilities/preProcessing/mapFieldsPar/MapVolFields.H

@@ -48,7 +48,7 @@ void evaluateConstraintTypes(GeometricField<Type, fvPatchField, volMesh>& fld)
 
     if
     (
-        commsType == UPstream::commsTypes::blocking
+        commsType == UPstream::commsTypes::buffered
      || commsType == UPstream::commsTypes::nonBlocking
     )
     {