Add lammps_flush_buffers() library function

doc/src/Library_utility.rst

@@ -13,6 +13,7 @@ functions.  They do not directly call the LAMMPS library.
 - :cpp:func:`lammps_fix_external_set_virial_peratom`
 - :cpp:func:`lammps_fix_external_set_vector_length`
 - :cpp:func:`lammps_fix_external_set_vector`
+- :cpp:func:`lammps_flush_buffers`
 - :cpp:func:`lammps_free`
 - :cpp:func:`lammps_is_running`
 - :cpp:func:`lammps_force_timeout`
@@ -72,6 +73,11 @@ where such memory buffers were allocated that require the use of
 
 -----------------------
 
+.. doxygenfunction:: lammps_flush_buffers
+   :project: progguide
+
+-----------------------
+
 .. doxygenfunction:: lammps_free
    :project: progguide
 

src/library.cpp

@@ -5439,6 +5439,25 @@ void lammps_fix_external_set_vector(void *handle, const char *id, int idx, doubl
 
 /* ---------------------------------------------------------------------- */
 
+/** Flush output buffers
+
+\verbatim embed:rst
+This function can be used to force output to be written to screen and logfiles
+to simplify capturing output from LAMMPS library calls.
+\endverbatim
+ *
+ * \param  handle    pointer to a previously created LAMMPS instance cast to ``void *``.
+ */
+void lammps_flush_buffers(void *handle) {
+  LAMMPS *lmp = (LAMMPS *) handle;
+  if (lmp->screen) fflush(lmp->screen);
+  if (lmp->logfile) fflush(lmp->logfile);
+  if (lmp->universe->uscreen)  fflush(lmp->universe->uscreen);
+  if (lmp->universe->ulogfile) fflush(lmp->universe->ulogfile);
+}
+
+/* ---------------------------------------------------------------------- */
+
 /** Free memory buffer allocated by LAMMPS.
  *
 \verbatim embed:rst

src/library.h

@@ -246,6 +246,8 @@ void lammps_fix_external_set_virial_peratom(void *handle, const char *id, double
 void lammps_fix_external_set_vector_length(void *handle, const char *id, int len);
 void lammps_fix_external_set_vector(void *handle, const char *id, int idx, double val);
 
+void lammps_flush_buffers(void *ptr);
+
 void lammps_free(void *ptr);
 
 int lammps_is_running(void *handle);