DiskStorage can allocate and free blocks of arbitrary sizes

block-storage/src/test/java/org/lucares/pdb/diskstorage/DiskStorageTest.java

@@ -11,6 +11,7 @@ import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
 
 import org.lucares.utils.file.FileUtils;
+import org.testng.Assert;
 import org.testng.annotations.AfterMethod;
 import org.testng.annotations.BeforeMethod;
 import org.testng.annotations.Test;
@@ -135,6 +136,130 @@ public class DiskStorageTest {
 		}
 	}
 
+	@Test(enabled = true, expectedExceptions = IllegalArgumentException.class)
+	public void testAllocationSmallerThanMinimalBlockSize() throws Exception {
+		final Path databaseFile = dataDirectory.resolve("db.ds");
+
+		try (DiskStorage ds = new DiskStorage(databaseFile)) {
+
+			final int blockSize = 31; // minimal block size is 32
+			ds.allocateBlock(blockSize);
+		}
+	}
+
+	@Test(enabled = true)
+	public void testAllocateAndFreeSingleBlockInFreeList() throws Exception {
+		final Path databaseFile = dataDirectory.resolve("db.ds");
+
+		try (DiskStorage ds = new DiskStorage(databaseFile)) {
+
+			final int blockSize = 32;
+			final long block_8_39 = ds.allocateBlock(blockSize);
+			final long block_40_71 = ds.allocateBlock(blockSize);
+			final long block_72_103 = ds.allocateBlock(blockSize);
+
+			Assert.assertEquals(block_8_39, 8);
+			Assert.assertEquals(block_40_71, 40);
+			Assert.assertEquals(block_72_103, 72);
+
+			ds.free(block_40_71, blockSize);
+
+			// should reuse the block we just freed
+			final long actual_block_40_71 = ds.allocateBlock(blockSize);
+
+			Assert.assertEquals(actual_block_40_71, 40);
+		}
+	}
+
+	@Test(enabled = true)
+	public void testAllocateAndFreeMultipleBlocksInFreeList() throws Exception {
+		final Path databaseFile = dataDirectory.resolve("db.ds");
+
+		try (DiskStorage ds = new DiskStorage(databaseFile)) {
+
+			final int blockSize = 32;
+			ds.allocateBlock(blockSize);
+			final long block_40_71 = ds.allocateBlock(blockSize);
+			final long block_72_103 = ds.allocateBlock(blockSize);
+			final long block_104_135 = ds.allocateBlock(blockSize);
+			ds.allocateBlock(blockSize);
+
+			ds.free(block_72_103, blockSize);
+			ds.free(block_104_135, blockSize);
+			ds.free(block_40_71, blockSize); // the block with the smaller index is freed last, this increases line
+												// coverage, because there is a branch for prepending the root node
+
+			// should reuse the first block we just freed
+			// this removes the root node of the free list
+			final long actual_block_40_71 = ds.allocateBlock(blockSize);
+			Assert.assertEquals(actual_block_40_71, 40);
+
+			// should reuse the second block we just freed
+			final long actual_block_72_103 = ds.allocateBlock(blockSize);
+			Assert.assertEquals(actual_block_72_103, 72);
+
+			// should reuse the third block we just freed
+			// this removes the last node of the free list
+			final long actual_block_104_135 = ds.allocateBlock(blockSize);
+			Assert.assertEquals(actual_block_104_135, 104);
+
+			final long block_168_199 = ds.allocateBlock(blockSize);
+			Assert.assertEquals(block_168_199, 168);
+		}
+	}
+
+	@Test(enabled = true)
+	public void testAllocateAndFreeInsertFreeNodeInTheMiddleOfTheFreeList() throws Exception {
+		final Path databaseFile = dataDirectory.resolve("db.ds");
+
+		try (DiskStorage ds = new DiskStorage(databaseFile)) {
+
+			final int blockSize = 32;
+			ds.allocateBlock(blockSize);
+			ds.allocateBlock(blockSize);
+			final long block_72_103 = ds.allocateBlock(blockSize);
+			final long block_104_135 = ds.allocateBlock(blockSize);
+			final long block_136_167 = ds.allocateBlock(blockSize);
+
+			// free the last block first, to increase code coverage
+			ds.free(block_136_167, blockSize);
+			ds.free(block_72_103, blockSize);
+			ds.free(block_104_135, blockSize);
+
+			// the first free block is re-used
+			final long actual_block_72_103 = ds.allocateBlock(blockSize);
+			Assert.assertEquals(actual_block_72_103, block_72_103);
+
+			final long actual_block_104_135 = ds.allocateBlock(blockSize);
+			Assert.assertEquals(actual_block_104_135, block_104_135);
+
+			final long actual_block_136_167 = ds.allocateBlock(blockSize);
+			Assert.assertEquals(actual_block_136_167, block_136_167);
+		}
+	}
+
+	@Test(enabled = true)
+	public void testAllocateAndFreeMultipleBlocksWithDifferentSizes() throws Exception {
+		final Path databaseFile = dataDirectory.resolve("db.ds");
+
+		try (DiskStorage ds = new DiskStorage(databaseFile)) {
+
+			final int blockSizeSmall = 32;
+			final int blockSizeBig = 64;
+			ds.allocateBlock(blockSizeSmall);
+			ds.allocateBlock(blockSizeSmall);
+			final long big_block_72_103 = ds.allocateBlock(blockSizeBig);
+			final long small_block_136_167 = ds.allocateBlock(blockSizeSmall);
+			ds.allocateBlock(blockSizeSmall);
+
+			ds.free(big_block_72_103, blockSizeBig);
+			ds.free(small_block_136_167, blockSizeSmall);
+
+			final long actual_small_block_136_167 = ds.allocateBlock(blockSizeSmall);
+			Assert.assertEquals(actual_small_block_136_167, small_block_136_167);
+		}
+	}
+
 	private void assertAllValuesAreEqual(final DiskBlock diskBlock, final byte expectedVal) {
 		final byte[] buffer = diskBlock.getBuffer();
 		for (int i = 0; i < buffer.length; i++) {