Fix POJO generator

  - missing semicolon in POJO generator
  - make file name and class name consistent
  - do not generate NAMES field if it is too long
    - Right now each string in NAMES field occupies 4bytes in the static initializer of class,
so the limit is ~ 65536/(2*2*4) since we need to load all strings from NAMES array and ColInfo
in static initializer. And static initializer influences the size of
resulting class.
  - do not generate ColInfo if it is not necessary.

src/main/java/hex/gbm/GBM.java

@@ -143,8 +143,8 @@ private GBMModel(GBMModel prior, Key[][] treeKeys, double[] errs, ConfusionMatri
       if(family == Family.bernoulli) {
         bodyCtxSB.i().p("// Compute Probabilities for Bernoulli 0-1 classifier").nl();
         bodyCtxSB.i().p("double fx = preds[1] + "+initialPrediction+";").nl();
-        bodyCtxSB.i().p("preds[2] = 1.0f/(float)(1.0f+Math.exp(-fx))").nl();
-        bodyCtxSB.i().p("preds[1] = 1.0f-preds[2]").nl();
+        bodyCtxSB.i().p("preds[2] = 1.0f/(float)(1.0f+Math.exp(-fx));").nl();
+        bodyCtxSB.i().p("preds[1] = 1.0f-preds[2];").nl();
       }
       else if (isClassifier()) {
         bodyCtxSB.i().p("// Compute Probabilities for classifier (scale via http://www.hongliangjie.com/2011/01/07/logsum/)").nl();

src/main/java/water/Model.java

@@ -656,7 +656,13 @@ protected SB toJavaSuper( SB sb ) {
 
     return sb;
   }
-  private SB toJavaNAMES( SB sb ) { return JCodeGen.toStaticVar(sb, "NAMES", _names, "Names of columns used by model."); }
+  private SB toJavaNAMES( SB sb ) {
+    //
+    int limit = ((1<<16) /* Max size of class */ - 4 * 500 /* Free space for loading any static stuff */ ) / (4*2*2); // Static initialized needs 4 instructions to load String from constant pool + load ColInfo
+    return _names.length < limit ?
+        JCodeGen.toStaticVar(sb, "NAMES", _names, "Names of columns used by model.") :
+        JCodeGen.toStaticVar(sb, "NAMES", JCodeGen.EMPTY_SA, "Names of columns used by model. WARNING: It is too large to be generated!");
+  }
   protected SB toJavaNCLASSES( SB sb ) { return isClassifier() ? JCodeGen.toStaticVar(sb, "NCLASSES", nclasses(), "Number of output classes included in training data response column.") : sb; }
   private SB toJavaDOMAINS( SB sb, SB fileContextSB ) {
     sb.nl();
@@ -667,7 +673,7 @@ private SB toJavaDOMAINS( SB sb, SB fileContextSB ) {
       String[] dom = _domains[i];
       String colInfoClazz = "ColInfo_"+i;
       sb.i(1).p("/* ").p(_names[i]).p(" */ ");
-      sb.p(colInfoClazz).p(".VALUES");
+      if (dom != null) sb.p(colInfoClazz).p(".VALUES"); else sb.p("null");
       if (i!=_domains.length-1) sb.p(',');
       sb.nl();
       fileContextSB.i().p("// The class representing column ").p(_names[i]).nl();

src/main/java/water/api/SaveModel.java

@@ -1,13 +1,15 @@
 package water.api;
 
 import java.io.*;
+
 import static water.util.FSUtils.isHdfs;
 import static water.util.FSUtils.isS3N;
 
 import java.io.File;
 import java.io.IOException;
 
 import hex.glm.GLMModel;
+
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 
@@ -16,6 +18,7 @@
 import water.serial.Model2FileBinarySerializer;
 import water.serial.Model2HDFSBinarySerializer;
 import water.util.FSUtils;
+import water.util.JCodeGen;
 
 public class SaveModel extends Func {
   static final int API_WEAVER = 1;
@@ -48,7 +51,7 @@ private void saveToLocalFS() {
       // Create folder
       parentDir.mkdirs();
       // Save parent model
-      new Model2FileBinarySerializer().save(model, new File(parentDir, model._key.toString()));
+      new Model2FileBinarySerializer().save(model, new File(parentDir, JCodeGen.toJavaId(model._key.toString())));
       // Write to model_names
       File model_names = new File(parentDir, "model_names");
       FileOutputStream is = new FileOutputStream(model_names);
@@ -61,8 +64,8 @@ private void saveToLocalFS() {
         Model[] models = getCrossValModels(model);
         System.out.println(models);
         for (Model m : models) {
-          new Model2FileBinarySerializer().save(m, new File(parentDir, m._key.toString()));
-          br.write(m._key.toString());
+          new Model2FileBinarySerializer().save(m, new File(parentDir, JCodeGen.toJavaId(m._key.toString())));
+          br.write(JCodeGen.toJavaId(m._key.toString()));
           br.newLine();
         }
       }
@@ -80,7 +83,7 @@ private void saveToHdfs() {
       if (force && fs.exists(parentDir)) fs.delete(parentDir);
       fs.mkdirs(parentDir);
       // Save parent model
-      new Model2HDFSBinarySerializer(fs, force).save(model, new Path(parentDir, model._key.toString()));
+      new Model2HDFSBinarySerializer(fs, force).save(model, new Path(parentDir, JCodeGen.toJavaId(model._key.toString())));
       // Save parent model key to model_names file
       Path model_names = new Path(parentDir, "model_names");
       BufferedWriter br = new BufferedWriter(new OutputStreamWriter(fs.create(model_names,true)));
@@ -89,8 +92,8 @@ private void saveToHdfs() {
       if (save_cv) {
         Model[] models = getCrossValModels(model);
         for (Model m : models ) {
-          new Model2HDFSBinarySerializer(fs, force).save(m, new Path(parentDir, m._key.toString()));
-          br.write(m._key.toString());
+          new Model2HDFSBinarySerializer(fs, force).save(m, new Path(parentDir, JCodeGen.toJavaId(m._key.toString())));
+          br.write(JCodeGen.toJavaId(m._key.toString()));
           br.newLine();
         }
       }

src/main/java/water/util/JCodeGen.java

@@ -5,6 +5,8 @@
 
 public class JCodeGen {
 
+  public static final String[] EMPTY_SA = new String[] {} ;
+
   /** Generates data sample as a dedicated class with static <code>double[][]</code> member. */
   public static SB toClass(SB sb, String classSig, String varname, Frame f, int nrows, String comment) {
     sb.p(classSig).p(" {").nl().ii(1);