Make I/O during indexing generic

src/main/java/com/github/dbmdz/solrocr/reader/BaseSourceReader.java

@@ -2,6 +2,9 @@
 
 import com.github.dbmdz.solrocr.model.SourcePointer;
 import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 
@@ -127,7 +130,7 @@ public String readAsciiString(int start, int len) throws IOException {
     if (start + len > this.length()) {
       len = this.length() - start;
     }
-    StringBuilder sb = new StringBuilder();
+    StringBuilder sb = new StringBuilder(len);
     int numRead = 0;
     while (numRead < len) {
       Section section = getAsciiSection(start + numRead);
@@ -242,4 +245,54 @@ public Section getAsciiSection(int offset) throws IOException {
 
     return section;
   }
+
+  /**
+   * Get a {@link java.io.Reader} instance for this SourceReader.
+   *
+   * <p>This is a generic implementation that should be overriden with a more efficient
+   * source-specific implementation, if available.
+   */
+  public Reader getReader() {
+    return new InputStreamReader(
+        new InputStream() {
+          int position = 0;
+          final byte[] buf = new byte[sectionSize];
+          int currentSectionStart = -1;
+          int currentSectionEnd = -1;
+
+          @Override
+          public int read() throws IOException {
+            if (position >= length()) {
+              return -1;
+            }
+            if (position > currentSectionEnd) {
+              currentSectionEnd =
+                  position + BaseSourceReader.this.readBytes(buf, 0, position, sectionSize);
+              currentSectionStart = position;
+            }
+            int out = buf[position - currentSectionStart] & 0xFF;
+            position++;
+            return out;
+          }
+
+          @Override
+          public int read(byte[] b, int off, int len) throws IOException {
+            int numRead = BaseSourceReader.this.readBytes(buf, off, position, len);
+            this.position += numRead;
+            return numRead;
+          }
+
+          @Override
+          public long skip(long n) throws IOException {
+            int toSkip = Math.min(length() - position, (int) n);
+            this.position += toSkip;
+            return toSkip;
+          }
+
+          @Override
+          public void close() throws IOException {
+            BaseSourceReader.this.close();
+          }
+        });
+  }
 }

src/main/java/com/github/dbmdz/solrocr/reader/ExitingSourceReader.java

@@ -2,6 +2,7 @@
 
 import com.github.dbmdz.solrocr.model.SourcePointer;
 import java.io.IOException;
+import java.io.Reader;
 import java.util.Locale;
 import org.apache.lucene.index.QueryTimeout;
 
@@ -74,4 +75,9 @@ public Section getAsciiSection(int offset) throws IOException {
     checkAndThrow();
     return input.getAsciiSection(offset);
   }
+
+  @Override
+  public Reader getReader() throws IOException {
+    return input.getReader();
+  }
 }

src/main/java/com/github/dbmdz/solrocr/reader/FileSourceReader.java

@@ -2,8 +2,11 @@
 
 import com.github.dbmdz.solrocr.model.SourcePointer;
 import java.io.IOException;
+import java.io.Reader;
 import java.nio.ByteBuffer;
+import java.nio.channels.Channels;
 import java.nio.channels.FileChannel;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
@@ -43,4 +46,9 @@ public void close() throws IOException {
   public String getIdentifier() {
     return this.path.toString();
   }
+
+  @Override
+  public Reader getReader() {
+    return Channels.newReader(this.chan, StandardCharsets.UTF_8.newDecoder(), -1);
+  }
 }

src/main/java/com/github/dbmdz/solrocr/reader/MultiFileSourceReader.java

@@ -3,9 +3,14 @@
 import com.github.dbmdz.solrocr.model.SourcePointer;
 import com.github.dbmdz.solrocr.util.ArrayUtils;
 import java.io.IOException;
+import java.io.Reader;
 import java.lang.invoke.MethodHandles;
 import java.nio.ByteBuffer;
+import java.nio.channels.Channels;
 import java.nio.channels.FileChannel;
+import java.nio.channels.ReadableByteChannel;
+import java.nio.charset.CharsetDecoder;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
@@ -124,4 +129,43 @@ public String getIdentifier() {
             .map(p -> p.toAbsolutePath().toString())
             .collect(Collectors.joining(", ")));
   }
+
+  @Override
+  public Reader getReader() {
+    CharsetDecoder decoder = StandardCharsets.UTF_8.newDecoder();
+    ReadableByteChannel multiFileChannel =
+        new ReadableByteChannel() {
+          private boolean closed = false;
+          private int position = 0;
+
+          @Override
+          public boolean isOpen() {
+            return !closed;
+          }
+
+          @Override
+          public void close() throws IOException {
+            MultiFileSourceReader.this.close();
+            this.closed = true;
+          }
+
+          @Override
+          public int read(ByteBuffer byteBuffer) throws IOException {
+            if (!byteBuffer.hasArray()) {
+              throw new UnsupportedOperationException(
+                  "Currently only ByteBuffers backed by an array are supported.");
+            }
+            int numRead =
+                MultiFileSourceReader.this.readBytes(
+                    byteBuffer.array(), byteBuffer.arrayOffset(), position, byteBuffer.remaining());
+            if (numRead > 0) {
+              byteBuffer.position(byteBuffer.position() + numRead);
+              this.position += numRead;
+            }
+            return numRead;
+          }
+        };
+
+    return Channels.newReader(multiFileChannel, decoder, -1);
+  }
 }

src/main/java/com/github/dbmdz/solrocr/reader/SourceReader.java

@@ -2,6 +2,7 @@
 
 import com.github.dbmdz.solrocr.model.SourcePointer;
 import java.io.IOException;
+import java.io.Reader;
 
 /** API for reading data from a source. */
 public interface SourceReader {
@@ -36,6 +37,8 @@ public interface SourceReader {
    */
   Section getAsciiSection(int offset) throws IOException;
 
+  Reader getReader() throws IOException;
+
   class Section {
     public final int start;
     public final int end;

src/main/java/com/github/dbmdz/solrocr/reader/StringSourceReader.java

@@ -1,6 +1,9 @@
 package com.github.dbmdz.solrocr.reader;
 
 import com.github.dbmdz.solrocr.model.SourcePointer;
+import java.io.IOException;
+import java.io.Reader;
+import java.io.StringReader;
 
 /** SourceReader that reads from a String. */
 public class StringSourceReader implements SourceReader {
@@ -28,6 +31,11 @@ public Section getAsciiSection(int offset) {
     return new Section(0, str.length(), str);
   }
 
+  @Override
+  public Reader getReader() throws IOException {
+    return new StringReader(str);
+  }
+
   @Override
   public int length() {
     return this.str.length();

src/main/java/solrocr/ExternalUtf8ContentFilterFactory.java

@@ -2,19 +2,15 @@
 
 import com.github.dbmdz.solrocr.lucene.filters.ExternalUtf8ContentFilter;
 import com.github.dbmdz.solrocr.model.SourcePointer;
-import com.github.dbmdz.solrocr.reader.MultiFileReader;
 import com.github.dbmdz.solrocr.util.Utf8;
 import com.google.common.collect.ImmutableList;
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.IOException;
-import java.io.InputStreamReader;
 import java.io.Reader;
 import java.io.StringReader;
 import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
-import java.nio.charset.StandardCharsets;
-import java.nio.file.Files;
 import java.nio.file.StandardOpenOption;
 import java.util.List;
 import java.util.Locale;
@@ -67,24 +63,16 @@ public Reader create(Reader input) {
       // This is very expensive, but we need this since all IO from here on out is character-based.
       toCharOffsets(pointer);
 
-      Reader r;
       if (pointer.sources.isEmpty()) {
         throw new RuntimeException(
             "No source files could be determined from pointer. "
                 + "Is it pointing to files that exist and are readable? "
                 + "Pointer was: "
                 + ptrStr);
-      } else if (pointer.sources.size() > 1) {
-        r =
-            new MultiFileReader(
-                pointer.sources.stream().map(s -> s.path).collect(Collectors.toList()));
-      } else {
-        r =
-            new InputStreamReader(
-                Files.newInputStream(pointer.sources.get(0).path, StandardOpenOption.READ),
-                StandardCharsets.UTF_8);
       }
-
+      // NOTE: Section size doesn't matter much, since we only use the APIs for unaligned
+      // reads through the Reader implementations.
+      Reader r = pointer.getReader(512 * 1024, 0).getReader();
       List<SourcePointer.Region> charRegions =
           pointer.sources.stream().flatMap(s -> s.regions.stream()).collect(Collectors.toList());
       return new ExternalUtf8ContentFilter(new BufferedReader(r), charRegions, ptrStr);

src/test/java/com/github/dbmdz/solrocr/formats/alto/AltoParserTest.java

@@ -128,6 +128,7 @@ public void testMultiFileParse() throws XMLStreamException, IOException {
             .filter(p -> p.getFileName().toString().startsWith("1860-"))
             .map(Path::toAbsolutePath)
             .map(Path::toString)
+            .sorted()
             .collect(Collectors.joining("+"));
     List<OcrBox> boxes =
         new AltoParser(filterFac.create(new StringReader(ptr)))

src/test/java/com/github/dbmdz/solrocr/lucene/ExternalUtf8ContentFilterTest.java

@@ -4,7 +4,6 @@
 
 import com.github.dbmdz.solrocr.lucene.filters.ExternalUtf8ContentFilter;
 import com.github.dbmdz.solrocr.model.SourcePointer.Region;
-import com.github.dbmdz.solrocr.reader.MultiFileReader;
 import com.github.dbmdz.solrocr.util.Utf8;
 import com.google.common.collect.ImmutableList;
 import java.io.BufferedReader;
@@ -149,17 +148,4 @@ public void multipleLongerFiles() throws IOException {
       assertThat(filtered).isEqualTo(fullText);
     }
   }
-
-  @Test
-  public void testMultiFileReader() throws IOException {
-    Path aPath = Paths.get("src/test/resources/data/alto_multi/1865-05-24_01-00001.xml");
-    Path bPath = Paths.get("src/test/resources/data/alto_multi/1865-05-24_01-00002.xml");
-    try (MultiFileReader r = new MultiFileReader(ImmutableList.of(aPath, bPath))) {
-      String fromReader = IOUtils.toString(r);
-      String aText = new String(Files.readAllBytes(aPath), StandardCharsets.UTF_8);
-      String bText = new String(Files.readAllBytes(bPath), StandardCharsets.UTF_8);
-      String fromFiles = aText + bText;
-      assertThat(fromReader).isEqualTo(fromFiles);
-    }
-  }
 }