Minor changes to code layout for readability

extensions/parquet/base/src/main/java/io/deephaven/parquet/base/ColumnChunkReaderImpl.java

@@ -191,15 +191,7 @@ private Dictionary getDictionary(final SeekableChannelContext channelContext) {
         } else {
             return NULL_DICTIONARY;
         }
-        // Use the context object provided by the caller, or create (and close) a new one
-        try (
-                final ContextHolder holder = SeekableChannelContext.ensureContext(channelsProvider, channelContext);
-                final SeekableByteChannel ch =
-                        channelsProvider.getReadChannel(holder.get(), getURI()).position(dictionaryPageOffset)) {
-            return readDictionary(ch, holder.get());
-        } catch (IOException e) {
-            throw new UncheckedIOException(e);
-        }
+        return readDictionary(dictionaryPageOffset, channelContext);
     }
 
     @Override
@@ -218,31 +210,37 @@ public SeekableChannelsProvider getChannelsProvider() {
     }
 
     @NotNull
-    private Dictionary readDictionary(SeekableByteChannel ch, SeekableChannelContext channelContext)
-            throws IOException {
-        // explicitly not closing this, caller is responsible
-        final PageHeader pageHeader = readPageHeader(ch);
-        if (pageHeader.getType() != PageType.DICTIONARY_PAGE) {
-            // In case our fallback in getDictionary was too optimistic...
-            return NULL_DICTIONARY;
-        }
-        final DictionaryPageHeader dictHeader = pageHeader.getDictionary_page_header();
-        final int compressedPageSize = pageHeader.getCompressed_page_size();
-        final BytesInput payload;
-        try (final InputStream in = (compressedPageSize == 0) ? null
-                : SeekableChannelsProvider.channelPositionInputStream(channelsProvider, ch, compressedPageSize)) {
-            if (compressedPageSize == 0) {
-                // Sometimes the size is explicitly empty, just use an empty payload
-                payload = BytesInput.empty();
-            } else {
-                payload = decompressor.decompress(in, compressedPageSize, pageHeader.getUncompressed_page_size(),
-                        channelContext);
+    private Dictionary readDictionary(long dictionaryPageOffset, SeekableChannelContext channelContext) {
+        // Use the context object provided by the caller, or create (and close) a new one
+        try (
+                final ContextHolder holder = SeekableChannelContext.ensureContext(channelsProvider, channelContext);
+                final SeekableByteChannel ch =
+                        channelsProvider.getReadChannel(holder.get(), getURI()).position(dictionaryPageOffset)) {
+            final PageHeader pageHeader = readPageHeader(ch);
+            if (pageHeader.getType() != PageType.DICTIONARY_PAGE) {
+                // In case our fallback in getDictionary was too optimistic...
+                return NULL_DICTIONARY;
+            }
+            final DictionaryPageHeader dictHeader = pageHeader.getDictionary_page_header();
+            final int compressedPageSize = pageHeader.getCompressed_page_size();
+            final BytesInput payload;
+            try (final InputStream in = (compressedPageSize == 0) ? null
+                    : channelsProvider.getInputStream(ch, compressedPageSize)) {
+                if (compressedPageSize == 0) {
+                    // Sometimes the size is explicitly empty, just use an empty payload
+                    payload = BytesInput.empty();
+                } else {
+                    payload = decompressor.decompress(in, compressedPageSize, pageHeader.getUncompressed_page_size(),
+                            holder.get());
+                }
+                final Encoding encoding = Encoding.valueOf(dictHeader.getEncoding().name());
+                final DictionaryPage dictionaryPage = new DictionaryPage(payload, dictHeader.getNum_values(), encoding);
+                // We are safe to not copy the payload because the Dictionary doesn't hold a reference to dictionaryPage
+                // or payload and thus doesn't hold a reference to the input stream.
+                return encoding.initDictionary(path, dictionaryPage);
             }
-            final Encoding encoding = Encoding.valueOf(dictHeader.getEncoding().name());
-            final DictionaryPage dictionaryPage = new DictionaryPage(payload, dictHeader.getNum_values(), encoding);
-            // We are safe to not copy the payload because the Dictionary doesn't hold a reference to dictionaryPage or
-            // payload and thus doesn't hold a reference to the input stream.
-            return encoding.initDictionary(path, dictionaryPage);
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
         }
     }
 
@@ -318,6 +316,9 @@ private org.apache.parquet.format.Encoding getEncoding(final PageHeader pageHead
         }
     }
 
+    /**
+     * Read the page header from the given channel and increment the channel position by the number of bytes read.
+     */
     private PageHeader readPageHeader(final SeekableByteChannel ch) throws IOException {
         // We expect page headers to be smaller than 128 bytes
         try (final InputStream in = SeekableChannelsProvider.channelPositionInputStream(channelsProvider, ch, 128)) {