LUCENE-9907: Remove unused methods in PackedInts (#94)

iverase · web-flow · commit 2a7951cd30fc · 2021-04-19T14:10:49.000+02:00
diff --git a/lucene/core/src/java/org/apache/lucene/util/packed/PackedInts.java b/lucene/core/src/java/org/apache/lucene/util/packed/PackedInts.java
@@ -18,10 +18,8 @@
 
 import java.io.IOException;
 import java.util.Arrays;
-import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.store.DataInput;
 import org.apache.lucene.store.DataOutput;
-import org.apache.lucene.store.IndexInput;
 import org.apache.lucene.util.Accountable;
 import org.apache.lucene.util.LongsRef;
 import org.apache.lucene.util.RamUsageEstimator;
@@ -506,13 +504,13 @@ public void clear() {
     }
 
     /**
-     * Save this mutable into <code>out</code>. Instantiating a reader from the generated data will
-     * return a reader with the same number of bits per value.
+     * Save this mutable into <code>out</code>. This method does not write any metadata to the
+     * stream, meaning that it is your responsibility to store it somewhere else in order to be able
+     * to recover data from the stream later on.
      */
     public void save(DataOutput out) throws IOException {
       Writer writer =
           getWriterNoHeader(out, getFormat(), size(), getBitsPerValue(), DEFAULT_BUFFER_SIZE);
-      writer.writeHeader();
       for (int i = 0; i < size(); ++i) {
         writer.add(get(i));
       }
@@ -632,14 +630,6 @@ protected Writer(DataOutput out, int valueCount, int bitsPerValue) {
       this.bitsPerValue = bitsPerValue;
     }
 
-    void writeHeader() throws IOException {
-      assert valueCount != -1;
-      CodecUtil.writeHeader(out, CODEC_NAME, VERSION_CURRENT);
-      out.writeVInt(bitsPerValue);
-      out.writeVInt(valueCount);
-      out.writeVInt(getFormat().getId());
-    }
-
     /** The format used to serialize values. */
     protected abstract PackedInts.Format getFormat();
 
@@ -716,24 +706,6 @@ public static Reader getReaderNoHeader(
     }
   }
 
-  /**
-   * Restore a {@link Reader} from a stream.
-   *
-   * @param in the stream to read data from
-   * @return a Reader
-   * @throws IOException If there is a low-level I/O error
-   * @lucene.internal
-   */
-  public static Reader getReader(DataInput in) throws IOException {
-    final int version = CodecUtil.checkHeader(in, CODEC_NAME, VERSION_START, VERSION_CURRENT);
-    final int bitsPerValue = in.readVInt();
-    assert bitsPerValue > 0 && bitsPerValue <= 64 : "bitsPerValue=" + bitsPerValue;
-    final int valueCount = in.readVInt();
-    final Format format = Format.byId(in.readVInt());
-
-    return getReaderNoHeader(in, format, version, valueCount, bitsPerValue);
-  }
-
   /**
    * Expert: Restore a {@link ReaderIterator} from a stream without reading metadata at the
    * beginning of the stream. This method is useful to restore data from streams which have been
@@ -756,76 +728,6 @@ public static ReaderIterator getReaderIteratorNoHeader(
     return new PackedReaderIterator(format, version, valueCount, bitsPerValue, in, mem);
   }
 
-  /**
-   * Retrieve PackedInts as a {@link ReaderIterator}
-   *
-   * @param in positioned at the beginning of a stored packed int structure.
-   * @param mem how much memory the iterator is allowed to use to read-ahead (likely to speed up
-   *     iteration)
-   * @return an iterator to access the values
-   * @throws IOException if the structure could not be retrieved.
-   * @lucene.internal
-   */
-  public static ReaderIterator getReaderIterator(DataInput in, int mem) throws IOException {
-    final int version = CodecUtil.checkHeader(in, CODEC_NAME, VERSION_START, VERSION_CURRENT);
-    final int bitsPerValue = in.readVInt();
-    assert bitsPerValue > 0 && bitsPerValue <= 64 : "bitsPerValue=" + bitsPerValue;
-    final int valueCount = in.readVInt();
-    final Format format = Format.byId(in.readVInt());
-    return getReaderIteratorNoHeader(in, format, version, valueCount, bitsPerValue, mem);
-  }
-
-  /**
-   * Expert: Construct a direct {@link Reader} from a stream without reading metadata at the
-   * beginning of the stream. This method is useful to restore data from streams which have been
-   * created using {@link PackedInts#getWriterNoHeader(DataOutput, Format, int, int, int)}.
-   *
-   * <p>The returned reader will have very little memory overhead, but every call to {@link
-   * Reader#get(int)} is likely to perform a disk seek.
-   *
-   * @param in the stream to read data from
-   * @param format the format used to serialize
-   * @param version the version used to serialize the data
-   * @param valueCount how many values the stream holds
-   * @param bitsPerValue the number of bits per value
-   * @return a direct Reader
-   * @lucene.internal
-   */
-  public static Reader getDirectReaderNoHeader(
-      final IndexInput in, Format format, int version, int valueCount, int bitsPerValue) {
-    checkVersion(version);
-    switch (format) {
-      case PACKED:
-        return new DirectPackedReader(bitsPerValue, valueCount, in);
-      case PACKED_SINGLE_BLOCK:
-        return new DirectPacked64SingleBlockReader(bitsPerValue, valueCount, in);
-      default:
-        throw new AssertionError("Unknown format: " + format);
-    }
-  }
-
-  /**
-   * Construct a direct {@link Reader} from an {@link IndexInput}. This method is useful to restore
-   * data from streams which have been created using {@link PackedInts#getWriter(DataOutput, int,
-   * int, float)}.
-   *
-   * <p>The returned reader will have very little memory overhead, but every call to {@link
-   * Reader#get(int)} is likely to perform a disk seek.
-   *
-   * @param in the stream to read data from
-   * @return a direct Reader
-   * @throws IOException If there is a low-level I/O error
-   * @lucene.internal
-   */
-  public static Reader getDirectReader(IndexInput in) throws IOException {
-    final int version = CodecUtil.checkHeader(in, CODEC_NAME, VERSION_START, VERSION_CURRENT);
-    final int bitsPerValue = in.readVInt();
-    assert bitsPerValue > 0 && bitsPerValue <= 64 : "bitsPerValue=" + bitsPerValue;
-    final int valueCount = in.readVInt();
-    final Format format = Format.byId(in.readVInt());
-    return getDirectReaderNoHeader(in, format, version, valueCount, bitsPerValue);
-  }
-
   /**
    * Create a packed integer array with the given amount of values initialized to 0. the valueCount
    * and the bitsPerValue cannot be changed after creation. All Mutables known by this factory are
@@ -913,49 +815,6 @@ public static Writer getWriterNoHeader(
     return new PackedWriter(format, out, valueCount, bitsPerValue, mem);
   }
 
-  /**
-   * Create a packed integer array writer for the given output, format, value count, and number of
-   * bits per value.
-   *
-   * <p>The resulting stream will be long-aligned. This means that depending on the format which is
-   * used under the hoods, up to 63 bits will be wasted. An easy way to make sure that no space is
-   * lost is to always use a <code>valueCount</code> that is a multiple of 64.
-   *
-   * <p>This method writes metadata to the stream, so that the resulting stream is sufficient to
-   * restore a {@link Reader} from it. You don't need to track <code>valueCount</code> or <code>
-   * bitsPerValue</code> by yourself. In case this is a problem, you should probably look at {@link
-   * #getWriterNoHeader(DataOutput, Format, int, int, int)}.
-   *
-   * <p>The <code>acceptableOverheadRatio</code> parameter controls how readers that will be
-   * restored from this stream trade space for speed by selecting a faster but potentially less
-   * memory-efficient implementation. An <code>acceptableOverheadRatio</code> of {@link
-   * PackedInts#COMPACT} will make sure that the most memory-efficient implementation is selected
-   * whereas {@link PackedInts#FASTEST} will make sure that the fastest implementation is selected.
-   * In case you are only interested in reading this stream sequentially later on, you should
-   * probably use {@link PackedInts#COMPACT}.
-   *
-   * @param out the data output
-   * @param valueCount the number of values
-   * @param bitsPerValue the number of bits per value
-   * @param acceptableOverheadRatio an acceptable overhead ratio per value
-   * @return a Writer
-   * @throws IOException If there is a low-level I/O error
-   * @lucene.internal
-   */
-  public static Writer getWriter(
-      DataOutput out, int valueCount, int bitsPerValue, float acceptableOverheadRatio)
-      throws IOException {
-    assert valueCount >= 0;
-
-    final FormatAndBits formatAndBits =
-        fastestFormatAndBits(valueCount, bitsPerValue, acceptableOverheadRatio);
-    final Writer writer =
-        getWriterNoHeader(
-            out, formatAndBits.format, valueCount, formatAndBits.bitsPerValue, DEFAULT_BUFFER_SIZE);
-    writer.writeHeader();
-    return writer;
-  }
-
   /**
    * Returns how many bits are required to hold values up to and including maxValue NOTE: This
    * method returns at least 1.
diff --git a/lucene/core/src/test/org/apache/lucene/util/packed/TestPackedInts.java b/lucene/core/src/test/org/apache/lucene/util/packed/TestPackedInts.java
@@ -25,7 +25,6 @@
 import java.util.List;
 import java.util.Locale;
 import java.util.Random;
-import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.store.ByteArrayDataInput;
 import org.apache.lucene.store.ByteBuffersDirectory;
 import org.apache.lucene.store.DataInput;
@@ -103,14 +102,9 @@ public void testPackedInts() throws IOException {
         final Directory d = newDirectory();
 
         IndexOutput out = d.createOutput("out.bin", newIOContext(random()));
-        final float acceptableOverhead;
-        if (iter == 0) {
-          // have the first iteration go through exact nbits
-          acceptableOverhead = 0.0f;
-        } else {
-          acceptableOverhead = random().nextFloat();
-        }
-        PackedInts.Writer w = PackedInts.getWriter(out, valueCount, nbits, acceptableOverhead);
+        final int mem = random().nextInt(2 * PackedInts.DEFAULT_BUFFER_SIZE);
+        PackedInts.Writer w =
+            PackedInts.getWriterNoHeader(out, PackedInts.Format.PACKED, valueCount, nbits, mem);
         final long startFp = out.getFilePointer();
 
         final int actualValueCount =
@@ -133,24 +127,11 @@ public void testPackedInts() throws IOException {
             w.getFormat().byteCount(PackedInts.VERSION_CURRENT, valueCount, w.bitsPerValue);
         assertEquals(bytes, fp - startFp);
 
-        { // test header
-          IndexInput in = d.openInput("out.bin", newIOContext(random()));
-          // header = codec header | bitsPerValue | valueCount | format
-          CodecUtil.checkHeader(
-              in,
-              PackedInts.CODEC_NAME,
-              PackedInts.VERSION_START,
-              PackedInts.VERSION_CURRENT); // codec header
-          assertEquals(w.bitsPerValue, in.readVInt());
-          assertEquals(valueCount, in.readVInt());
-          assertEquals(w.getFormat().getId(), in.readVInt());
-          assertEquals(startFp, in.getFilePointer());
-          in.close();
-        }
-
         { // test reader
           IndexInput in = d.openInput("out.bin", newIOContext(random()));
-          PackedInts.Reader r = PackedInts.getReader(in);
+          PackedInts.Reader r =
+              PackedInts.getReaderNoHeader(
+                  in, PackedInts.Format.PACKED, PackedInts.VERSION_CURRENT, valueCount, nbits);
           assertEquals(fp, in.getFilePointer());
           for (int i = 0; i < valueCount; i++) {
             assertEquals(
@@ -177,7 +158,14 @@ public void testPackedInts() throws IOException {
 
         { // test reader iterator next
           IndexInput in = d.openInput("out.bin", newIOContext(random()));
-          PackedInts.ReaderIterator r = PackedInts.getReaderIterator(in, bufferSize);
+          PackedInts.ReaderIterator r =
+              PackedInts.getReaderIteratorNoHeader(
+                  in,
+                  PackedInts.Format.PACKED,
+                  PackedInts.VERSION_CURRENT,
+                  valueCount,
+                  nbits,
+                  bufferSize);
           for (int i = 0; i < valueCount; i++) {
             assertEquals(
                 "index="
@@ -198,7 +186,14 @@ public void testPackedInts() throws IOException {
 
         { // test reader iterator bulk next
           IndexInput in = d.openInput("out.bin", newIOContext(random()));
-          PackedInts.ReaderIterator r = PackedInts.getReaderIterator(in, bufferSize);
+          PackedInts.ReaderIterator r =
+              PackedInts.getReaderIteratorNoHeader(
+                  in,
+                  PackedInts.Format.PACKED,
+                  PackedInts.VERSION_CURRENT,
+                  valueCount,
+                  nbits,
+                  bufferSize);
           int i = 0;
           while (i < valueCount) {
             final int count = TestUtil.nextInt(random(), 1, 95);
@@ -221,27 +216,6 @@ public void testPackedInts() throws IOException {
           assertEquals(fp, in.getFilePointer());
           in.close();
         }
-
-        { // test direct reader get
-          IndexInput in = d.openInput("out.bin", newIOContext(random()));
-          PackedInts.Reader intsEnum = PackedInts.getDirectReader(in);
-          for (int i = 0; i < valueCount; i++) {
-            final String msg =
-                "index="
-                    + i
-                    + " valueCount="
-                    + valueCount
-                    + " nbits="
-                    + nbits
-                    + " for "
-                    + intsEnum.getClass().getSimpleName();
-            final int index = random().nextInt(valueCount);
-            assertEquals(msg, values[index], intsEnum.get(index));
-          }
-          intsEnum.get(intsEnum.size() - 1);
-          assertEquals(fp, in.getFilePointer());
-          in.close();
-        }
         d.close();
       }
     }
@@ -288,13 +262,6 @@ public void testEndPointer() throws IOException {
           }
           assertEquals(msg, byteCount, in.getFilePointer());
 
-          // test direct reader
-          in.seek(0L);
-          final PackedInts.Reader directReader =
-              PackedInts.getDirectReaderNoHeader(in, format, version, valueCount, bpv);
-          directReader.get(valueCount - 1);
-          assertEquals(msg, byteCount, in.getFilePointer());
-
           // test reader
           in.seek(0L);
           PackedInts.getReaderNoHeader(in, format, version, valueCount, bpv);
@@ -480,15 +447,19 @@ public void testSingleValue() throws Exception {
     for (int bitsPerValue = 1; bitsPerValue <= 64; ++bitsPerValue) {
       Directory dir = newDirectory();
       IndexOutput out = dir.createOutput("out", newIOContext(random()));
-      PackedInts.Writer w = PackedInts.getWriter(out, 1, bitsPerValue, PackedInts.DEFAULT);
+      PackedInts.Writer w =
+          PackedInts.getWriterNoHeader(
+              out, PackedInts.Format.PACKED, 1, bitsPerValue, PackedInts.DEFAULT_BUFFER_SIZE);
       long value = 17L & PackedInts.maxValue(bitsPerValue);
       w.add(value);
       w.finish();
       final long end = out.getFilePointer();
       out.close();
 
       IndexInput in = dir.openInput("out", newIOContext(random()));
-      Reader reader = PackedInts.getReader(in);
+      Reader reader =
+          PackedInts.getReaderNoHeader(
+              in, PackedInts.Format.PACKED, PackedInts.VERSION_CURRENT, 1, bitsPerValue);
       String msg = "Impl=" + w.getClass().getSimpleName() + ", bitsPerValue=" + bitsPerValue;
       assertEquals(msg, 1, reader.size());
       assertEquals(msg, value, reader.get(0));
@@ -910,7 +881,13 @@ public void testSave() throws IOException {
         out.close();
 
         IndexInput in = directory.openInput("packed-ints.bin", IOContext.DEFAULT);
-        PackedInts.Reader reader = PackedInts.getReader(in);
+        PackedInts.Reader reader =
+            PackedInts.getReaderNoHeader(
+                in,
+                mutable.getFormat(),
+                PackedInts.VERSION_CURRENT,
+                mutable.size(),
+                mutable.getBitsPerValue());
         assertEquals(valueCount, reader.size());
         if (mutable instanceof Packed64SingleBlock) {
           // make sure that we used the right format so that the reader has
