From f74b9df0a7082d782df7b6e3d165cab73d588461 Mon Sep 17 00:00:00 2001
From: Viktor Lofgren <vlofgren@marginalia.nu>
Date: Thu, 31 Aug 2023 20:15:10 +0200
Subject: [PATCH] (array)  Don't use paging arrays when mapping small files for
 writing

---
 .../java/nu/marginalia/array/LongArray.java   | 11 ++++++++++-
 .../array/page/PagingLongArray.java           | 19 -------------------
 2 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/code/libraries/array/src/main/java/nu/marginalia/array/LongArray.java b/code/libraries/array/src/main/java/nu/marginalia/array/LongArray.java
index 7902e05a..05317a05 100644
--- a/code/libraries/array/src/main/java/nu/marginalia/array/LongArray.java
+++ b/code/libraries/array/src/main/java/nu/marginalia/array/LongArray.java
@@ -43,10 +43,19 @@ public interface LongArray extends LongArrayBase, LongArrayTransformations, Long
 
     /** Map an existing file for writing */
     static LongArray mmapForModifying(Path path) throws IOException {
-        return PagingLongArray.mapFileReadWrite(DEFAULT_PARTITIONING_SCHEME, path);
+        long sizeBytes = Files.size(path);
+        assert sizeBytes % WORD_SIZE == 0;
+
+        long size = sizeBytes / WORD_SIZE;
+
+        return mmapForWriting(path, size);
     }
 
     static LongArray mmapForWriting(Path path, long size) throws IOException {
+        if (size < MAX_CONTINUOUS_SIZE) {
+            return LongArrayPage.fromMmapReadWrite(path, 0, (int) size);
+        }
+
         return PagingLongArray.mapFileReadWrite(DEFAULT_PARTITIONING_SCHEME, path, size);
     }
 
diff --git a/code/libraries/array/src/main/java/nu/marginalia/array/page/PagingLongArray.java b/code/libraries/array/src/main/java/nu/marginalia/array/page/PagingLongArray.java
index 57961273..c26bafe4 100644
--- a/code/libraries/array/src/main/java/nu/marginalia/array/page/PagingLongArray.java
+++ b/code/libraries/array/src/main/java/nu/marginalia/array/page/PagingLongArray.java
@@ -62,25 +62,6 @@ public class PagingLongArray extends AbstractPagingArray<LongArrayPage, LongBuff
         return new PagingLongArray(partitioningScheme, pages, size);
     }
 
-    public static PagingLongArray mapFileReadWrite(ArrayPartitioningScheme partitioningScheme, Path file)
-            throws IOException
-    {
-        long sizeBytes = Files.size(file);
-        assert sizeBytes % WORD_SIZE == 0;
-
-        long size = sizeBytes / WORD_SIZE;
-
-        LongArrayPage[] pages = new LongArrayPage[partitioningScheme.getPartitions(size)];
-        long offset = 0;
-        for (int i = 0; i < pages.length; i++) {
-            int partitionSize = partitioningScheme.getRequiredPageSize(i, size);
-            pages[i] = LongArrayPage.fromMmapReadWrite(file, offset, partitionSize);
-            offset += partitionSize;
-        }
-
-        return new PagingLongArray(partitioningScheme, pages, size);
-    }
-
     public static PagingLongArray mapFileReadWrite(ArrayPartitioningScheme partitioningScheme, Path file, long size)
             throws IOException
     {