Fielddata: Merge ordinals APIs into BytesValues.WithOrdinals.

Mid-term we should switch from `BytesValues` to Lucene's doc values APIs, in
particular the `SortedSetDocValues` class. While `BytesValues.WithOrdinals` and
SortedSetDocValues expose the same functionality, `BytesValues.WithOrdinals`
exposes its ordinals via a different `Ordinals.Docs` object while
`SortedSetDocValues` exposes them on the same object as the one that holds the
values. This commit merges ordinals into `BytesValues.WithOrdinals` in order to
make both classes even closer.

Global ordinals were a bit tricky to migrate so I just changed them to use
Lucene's OrdinalMap that will soon (LUCENE-5767, scheduled for 4.9) have the
same optimizations as our global ordinals.

Close #6524

src/main/java/org/elasticsearch/index/fielddata/AbstractAtomicNumericFieldData.java

@@ -45,10 +45,10 @@ public BytesValues getBytesValues() {
         if (isFloat) {
             final DoubleValues values = getDoubleValues();
             return new BytesValues(values.isMultiValued()) {
+                private final BytesRef scratch = new BytesRef();
 
                 @Override
                 public int setDocument(int docId) {
-                    this.docId = docId;
                     return values.setDocument(docId);
                 }
 
@@ -67,10 +67,10 @@ public Order getOrder() {
         } else {
             final LongValues values = getLongValues();
             return new BytesValues(values.isMultiValued()) {
+                private final BytesRef scratch = new BytesRef();
 
                 @Override
                 public int setDocument(int docId) {
-                    this.docId = docId;
                     return values.setDocument(docId);
                 }
 

src/main/java/org/elasticsearch/index/fielddata/AtomicFieldData.java

@@ -20,29 +20,20 @@
 package org.elasticsearch.index.fielddata;
 
 import org.apache.lucene.index.TermsEnum;
+import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.index.fielddata.ScriptDocValues.Strings;
+import org.elasticsearch.index.fielddata.plain.AtomicFieldDataWithOrdinalsTermsEnum;
 
 /**
  * The thread safe {@link org.apache.lucene.index.AtomicReader} level cache of the data.
  */
 public interface AtomicFieldData<Script extends ScriptDocValues> extends RamUsage {
 
-    /**
-     * If this method returns false, this means that no document has multiple values. However this method may return true even if all
-     * documents are single-valued. So this method is useful for performing optimizations when the single-value case makes the problem
-     * simpler but cannot be used to actually check whether this instance is multi-valued.
-     */
-    boolean isMultiValued();
-
-    /**
-     * An upper limit of the number of unique values in this atomic field data.
-     */
-    long getNumberUniqueValues();
-
     /**
      * Use a non thread safe (lightweight) view of the values as bytes.
      */
     BytesValues getBytesValues();
-    
+
     /**
      * Returns a "scripting" based values.
      */
@@ -55,6 +46,65 @@ public interface AtomicFieldData<Script extends ScriptDocValues> extends RamUsag
 
     interface WithOrdinals<Script extends ScriptDocValues> extends AtomicFieldData<Script> {
 
+        public static final WithOrdinals<ScriptDocValues.Strings> EMPTY = new WithOrdinals<ScriptDocValues.Strings>() {
+
+            @Override
+            public Strings getScriptValues() {
+                return new ScriptDocValues.Strings(getBytesValues());
+            }
+
+            @Override
+            public void close() {
+            }
+
+            @Override
+            public long getMemorySizeInBytes() {
+                return 0;
+            }
+
+            @Override
+            public BytesValues.WithOrdinals getBytesValues() {
+                return new BytesValues.WithOrdinals(false) {
+
+                    @Override
+                    public int setDocument(int docId) {
+                        return 0;
+                    }
+
+                    @Override
+                    public long nextOrd() {
+                        return MISSING_ORDINAL;
+                    }
+
+                    @Override
+                    public BytesRef getValueByOrd(long ord) {
+                        throw new UnsupportedOperationException();
+                    }
+
+                    @Override
+                    public long getOrd(int docId) {
+                        return MISSING_ORDINAL;
+                    }
+
+                    @Override
+                    public long getMaxOrd() {
+                        return 0;
+                    }
+
+                    @Override
+                    public long currentOrd() {
+                        return MISSING_ORDINAL;
+                    }
+                };
+            }
+
+            @Override
+            public TermsEnum getTermsEnum() {
+                return new AtomicFieldDataWithOrdinalsTermsEnum(this);
+            }
+
+        };
+
         /**
          * Use a non thread safe (lightweight) view of the values as bytes.
          * @param needsHashes

src/main/java/org/elasticsearch/index/fielddata/AtomicGeoPointFieldData.java

@@ -32,10 +32,10 @@ public abstract class AtomicGeoPointFieldData<Script extends ScriptDocValues> im
     public BytesValues getBytesValues() {
         final GeoPointValues values = getGeoPointValues();
         return new BytesValues(values.isMultiValued()) {
+            private final BytesRef scratch = new BytesRef();
 
             @Override
             public int setDocument(int docId) {
-                this.docId = docId;
                 return values.setDocument(docId);
             }
 

src/main/java/org/elasticsearch/index/fielddata/BytesValues.java

@@ -19,10 +19,9 @@
 
 package org.elasticsearch.index.fielddata;
 
+import org.apache.lucene.index.SortedSetDocValues;
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.ElasticsearchIllegalStateException;
-import org.elasticsearch.index.fielddata.ordinals.Ordinals;
-import org.elasticsearch.index.fielddata.ordinals.Ordinals.Docs;
 
 /**
  * A state-full lightweight per document set of <code>byte[]</code> values.
@@ -44,11 +43,7 @@ public abstract class BytesValues {
      */
     public static final BytesValues EMPTY = new Empty();
 
-    private boolean multiValued;
-
-    protected final BytesRef scratch = new BytesRef();
-
-    protected int docId = -1;
+    private final boolean multiValued;
 
     /**
      * Creates a new {@link BytesValues} instance
@@ -114,20 +109,41 @@ public AtomicFieldData.Order getOrder() {
      */
     public static abstract class WithOrdinals extends BytesValues {
 
-        protected final Docs ordinals;
+        public static final long MIN_ORDINAL = 0;
+        public static final long MISSING_ORDINAL = SortedSetDocValues.NO_MORE_ORDS;
 
-        protected WithOrdinals(Ordinals.Docs ordinals) {
-            super(ordinals.isMultiValued());
-            this.ordinals = ordinals;
+        protected WithOrdinals(boolean multiValued) {
+            super(multiValued);
         }
 
         /**
-         * Returns the associated ordinals instance.
-         * @return the associated ordinals instance.
+         * Returns total unique ord count;
          */
-        public Ordinals.Docs ordinals() {
-            return ordinals;
-        }
+        public abstract long getMaxOrd();
+
+        /**
+         * The ordinal that maps to the relevant docId. If it has no value, returns
+         * <tt>0</tt>.
+         */
+        public abstract long getOrd(int docId);
+
+        /**
+         * Returns the next ordinal for the current docID set to {@link #setDocument(int)}.
+         * This method should only be called <tt>N</tt> times where <tt>N</tt> is the number
+         * returned from {@link #setDocument(int)}. If called more than <tt>N</tt> times the behavior
+         * is undefined.
+         *
+         * Note: This method will never return <tt>0</tt>.
+         *
+         * @return the next ordinal for the current docID set to {@link #setDocument(int)}.
+         */
+        public abstract long nextOrd();
+
+        /**
+         * Returns the current ordinal in the iteration
+         * @return the current ordinal in the iteration
+         */
+        public abstract long currentOrd();
 
         /**
          * Returns the value for the given ordinal.
@@ -137,18 +153,9 @@ public Ordinals.Docs ordinals() {
          */
         public abstract BytesRef getValueByOrd(long ord);
 
-        @Override
-        public int setDocument(int docId) {
-            this.docId = docId;
-            int length = ordinals.setDocument(docId);
-            assert (ordinals.getOrd(docId) != Ordinals.MISSING_ORDINAL) == length > 0 : "Doc: [" + docId + "] hasValue: [" + (ordinals.getOrd(docId) != Ordinals.MISSING_ORDINAL) + "] but length is [" + length + "]";
-            return length;
-        }
-
         @Override
         public BytesRef nextValue() {
-            assert docId != -1;
-            return getValueByOrd(ordinals.nextOrd());
+            return getValueByOrd(nextOrd());
         }
     }
 

src/main/java/org/elasticsearch/index/fielddata/DoubleValues.java

@@ -20,8 +20,6 @@
 package org.elasticsearch.index.fielddata;
 
 import org.elasticsearch.ElasticsearchIllegalStateException;
-import org.elasticsearch.index.fielddata.ordinals.Ordinals;
-import org.elasticsearch.index.fielddata.ordinals.Ordinals.Docs;
 
 /**
  * A state-full lightweight per document set of <code>double</code> values.
@@ -100,21 +98,13 @@ public AtomicFieldData.Order getOrder() {
      */
     public static abstract class WithOrdinals extends DoubleValues {
 
-        protected final Docs ordinals;
+        protected final BytesValues.WithOrdinals ordinals;
 
-        protected WithOrdinals(Ordinals.Docs ordinals) {
+        protected WithOrdinals(BytesValues.WithOrdinals ordinals) {
             super(ordinals.isMultiValued());
             this.ordinals = ordinals;
         }
 
-        /**
-         * Returns the associated ordinals instance.
-         * @return the associated ordinals instance.
-         */
-        public Docs ordinals() {
-            return ordinals;
-        }
-
         /**
          * Returns the value for the given ordinal.
          * @param ord the ordinal to lookup.

src/main/java/org/elasticsearch/index/fielddata/LongValues.java

@@ -20,8 +20,6 @@
 package org.elasticsearch.index.fielddata;
 
 import org.elasticsearch.ElasticsearchIllegalStateException;
-import org.elasticsearch.index.fielddata.ordinals.Ordinals;
-import org.elasticsearch.index.fielddata.ordinals.Ordinals.Docs;
 
 /**
  * A state-full lightweight per document set of <code>long</code> values.
@@ -101,21 +99,13 @@ public AtomicFieldData.Order getOrder() {
      */
     public static abstract class WithOrdinals extends LongValues {
 
-        protected final Docs ordinals;
+        protected final BytesValues.WithOrdinals ordinals;
 
-        protected WithOrdinals(Ordinals.Docs ordinals) {
+        protected WithOrdinals(BytesValues.WithOrdinals ordinals) {
             super(ordinals.isMultiValued());
             this.ordinals = ordinals;
         }
 
-        /**
-         * Returns the associated ordinals instance.
-         * @return the associated ordinals instance.
-         */
-        public Docs ordinals() {
-            return this.ordinals;
-        }
-
         /**
          * Returns the value for the given ordinal.
          * @param ord the ordinal to lookup.