Allow the users to change the compression rate of datasets. Compression is...

Allow the users to change the compression rate of datasets. Compression is switched off by default for performance.

examples/parameter_example.yml

@@ -25,6 +25,7 @@ Snapshots:
   basename:   output      # Common part of the name of output files
   time_first: 0.          # Time of the first output (in internal units)
   delta_time: 0.01        # Time difference between consecutive outputs (in internal units)
+  compression: 0          # (Optional) Set the level of compression of the HDF5 datasets [0-9]. 0 does no compression.
   UnitMass_in_cgs:     1  # (Optional) Unit system for the outputs (Grams)
   UnitLength_in_cgs:   1  # (Optional) Unit system for the outputs (Centimeters)
   UnitVelocity_in_cgs: 1  # (Optional) Unit system for the outputs (Centimeters per second)

src/engine.c

@@ -2918,6 +2918,8 @@ void engine_init(struct engine *e, struct space *s,
       parser_get_param_double(params, "Snapshots:delta_time");
   e->ti_nextSnapshot = 0;
   parser_get_param_string(params, "Snapshots:basename", e->snapshotBaseName);
+  e->snapshotCompression =
+      parser_get_opt_param_int(params, "Snapshots:compression", 0);
   e->snapshotUnits = malloc(sizeof(struct UnitSystem));
   units_init_default(e->snapshotUnits, params, "Snapshots", internal_units);
   e->dt_min = parser_get_param_double(params, "TimeIntegration:dt_min");

src/engine.h

@@ -150,6 +150,7 @@ struct engine {
   double deltaTimeSnapshot;
   int ti_nextSnapshot;
   char snapshotBaseName[200];
+  int snapshotCompression;
   struct UnitSystem *snapshotUnits;
 
   /* Statistics information */

src/serial_io.c

@@ -224,10 +224,12 @@ void prepareArray(hid_t grp, char* fileName, FILE* xmfFile,
   }
 
   /* Impose data compression */
-  h_err = H5Pset_deflate(h_prop, 4);
-  if (h_err < 0) {
-    error("Error while setting compression options for field '%s'.",
-          props.name);
+  if(e->snapshotCompression > 0) {
+    h_err = H5Pset_deflate(h_prop, e->snapshotCompression);
+    if (h_err < 0) {
+      error("Error while setting compression options for field '%s'.",
+	    props.name);
+    }
   }
 
   /* Create dataset */

src/single_io.c

@@ -261,10 +261,12 @@ void writeArray(struct engine* e, hid_t grp, char* fileName, FILE* xmfFile,
   }
 
   /* Impose data compression */
-  h_err = H5Pset_deflate(h_prop, 4);
-  if (h_err < 0) {
-    error("Error while setting compression options for field '%s'.",
-          props.name);
+  if (e->snapshotCompression > 0) {
+    h_err = H5Pset_deflate(h_prop, e->snapshotCompression);
+    if (h_err < 0) {
+      error("Error while setting compression options for field '%s'.",
+            props.name);
+    }
   }
 
   /* Create dataset */