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-rw-r--r--.gitignore3
-rw-r--r--README.md17
-rw-r--r--pom.xml6
-rw-r--r--src/main/java/io/trygvis/btree/Bits.java11
-rw-r--r--src/main/java/io/trygvis/btree/BtreeFile.java63
-rw-r--r--src/main/java/io/trygvis/btree/BtreeMap.java97
-rw-r--r--src/main/java/io/trygvis/btree/HeapFile.java2
-rw-r--r--src/main/java/io/trygvis/btree/HeapPage.java18
-rw-r--r--src/test/java/io/trygvis/btree/BtreeMapTest.java45
-rw-r--r--src/test/java/io/trygvis/btree/HeapPageTest.java51
-rw-r--r--src/test/java/io/trygvis/btree/HeapTest.java26
11 files changed, 317 insertions, 22 deletions
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5231862
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+.idea
+*.iml
+target
diff --git a/README.md b/README.md
index 6c93395..9062054 100644
--- a/README.md
+++ b/README.md
@@ -33,3 +33,20 @@ A heap page looks like this:
| header |
|-------------|
+BTree File
+==========
+
+BTree Item
+----------
+
+* `bytes[] key`
+* `int pageNo` - the page in the heap that contains the value.
+
+A heap page can contain many items so the heap page has to be scanned.
+
+
+Example BTree page
+------------------
+
+ [1, #], [7, #], [9, #]
+
diff --git a/pom.xml b/pom.xml
index c444f96..e7c9048 100644
--- a/pom.xml
+++ b/pom.xml
@@ -3,7 +3,11 @@
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
-
+ <parent>
+ <groupId>io.trygvis</groupId>
+ <artifactId>trygvis-parent</artifactId>
+ <version>1</version>
+ </parent>
<groupId>io.trygvis.btree</groupId>
<artifactId>btree</artifactId>
<version>1.0-SNAPSHOT</version>
diff --git a/src/main/java/io/trygvis/btree/Bits.java b/src/main/java/io/trygvis/btree/Bits.java
new file mode 100644
index 0000000..c38e865
--- /dev/null
+++ b/src/main/java/io/trygvis/btree/Bits.java
@@ -0,0 +1,11 @@
+package io.trygvis.btree;
+
+public class Bits {
+ public static byte[] toBytes(int i) {
+ return new byte[]{(byte) (i >> 24), (byte) (i >> 16), (byte) (i >> 8), (byte) i};
+ }
+
+ public static int intFromBytes(byte[] bytes) {
+ return (bytes[0] << 24) + (bytes[1] << 16) + (bytes[2] << 8) + bytes[2];
+ }
+}
diff --git a/src/main/java/io/trygvis/btree/BtreeFile.java b/src/main/java/io/trygvis/btree/BtreeFile.java
new file mode 100644
index 0000000..7300b5e
--- /dev/null
+++ b/src/main/java/io/trygvis/btree/BtreeFile.java
@@ -0,0 +1,63 @@
+package io.trygvis.btree;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.Iterator;
+
+public class BtreeFile implements Closeable {
+ private final HeapFile heap;
+ private final int keySize;
+ private final int itemsPerPage;
+
+ public BtreeFile(HeapFile heap, int keySize) throws IOException {
+ this.heap = heap;
+ this.keySize = keySize;
+ itemsPerPage = heap.PAGE_SIZE / keySize;
+
+ // Make sure we always have a page #0.
+ if (heap.pageCount() == 0) {
+ HeapPage root = heap.blankPage();
+ heap.writePage(root);
+ }
+ }
+
+ public void add(byte[] key, byte[] value) throws IOException {
+ HeapPage page = heap.loadPage(0);
+
+ ByteBuffer k = ByteBuffer.wrap(key);
+ ByteBuffer current;
+ ByteBuffer smaller;
+
+ Iterator<ByteBuffer> it = page.items().iterator();
+
+ int position = 0;
+
+ while(it.hasNext()) {
+ current = it.next();
+
+ int diff = k.compareTo(current);
+
+ if(diff < 0) {
+ break;
+ }
+ }
+
+// page.prepend();
+ }
+
+ @Override
+ public void close() throws IOException {
+ heap.close();
+ }
+
+ public static class BtreeItem {
+ private final byte[] from;
+ private final int page;
+
+ public BtreeItem(byte[] from, int page) {
+ this.from = from;
+ this.page = page;
+ }
+ }
+}
diff --git a/src/main/java/io/trygvis/btree/BtreeMap.java b/src/main/java/io/trygvis/btree/BtreeMap.java
new file mode 100644
index 0000000..06c348f
--- /dev/null
+++ b/src/main/java/io/trygvis/btree/BtreeMap.java
@@ -0,0 +1,97 @@
+package io.trygvis.btree;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.util.Collection;
+import java.util.Map;
+import java.util.Set;
+
+public class BtreeMap<K, V> implements Map<K, V>, Closeable {
+
+ public static interface Serializer<A> {
+ byte[] toBytes(A a);
+
+ A fromBytes(byte[] bytes);
+ }
+
+ private final BtreeFile tree;
+ private final Serializer<K> kSerializer;
+ private final Serializer<V> vSerializer;
+
+ public BtreeMap(BtreeFile tree, Serializer<K> kSerializer, Serializer<V> vSerializer) {
+ this.tree = tree;
+ this.kSerializer = kSerializer;
+ this.vSerializer = vSerializer;
+ }
+
+ @Override
+ public void close() throws IOException {
+ tree.close();
+ }
+
+ @Override
+ public int size() {
+ return 0;
+ }
+
+ @Override
+ public boolean isEmpty() {
+ return size() == 0;
+ }
+
+ @Override
+ public boolean containsKey(Object key) {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public boolean containsValue(Object value) {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public V get(Object key) {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public V put(K key, V value) {
+ try {
+ tree.add(kSerializer.toBytes(key), vSerializer.toBytes(value));
+
+ return null;
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ @Override
+ public V remove(Object key) {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public void putAll(Map<? extends K, ? extends V> m) {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public void clear() {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public Set<K> keySet() {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public Collection<V> values() {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public Set<Entry<K, V>> entrySet() {
+ throw new UnsupportedOperationException();
+ }
+}
diff --git a/src/main/java/io/trygvis/btree/HeapFile.java b/src/main/java/io/trygvis/btree/HeapFile.java
index 6bd0451..83b2f48 100644
--- a/src/main/java/io/trygvis/btree/HeapFile.java
+++ b/src/main/java/io/trygvis/btree/HeapFile.java
@@ -11,7 +11,7 @@ import static io.trygvis.btree.HeapPage.blankHeapPage;
import static java.nio.ByteBuffer.allocateDirect;
public class HeapFile implements Closeable {
- private final int PAGE_SIZE;
+ public final int PAGE_SIZE;
private final RandomAccessFile file;
private final FileChannel channel;
diff --git a/src/main/java/io/trygvis/btree/HeapPage.java b/src/main/java/io/trygvis/btree/HeapPage.java
index a931260..32ba0ef 100644
--- a/src/main/java/io/trygvis/btree/HeapPage.java
+++ b/src/main/java/io/trygvis/btree/HeapPage.java
@@ -53,11 +53,27 @@ public class HeapPage {
bytes.putInt(FREE_POSITION_INDEX, freePosition);
}
+ public void prepend(byte[] item) {
+ int bytesFree = bytesFree();
+ int bytesRequested = item.length;
+
+ if (bytesRequested > bytesFree) {
+ throw new PageOverflowException(bytesFree, bytesRequested);
+ }
+
+ byte[] array = bytes.array();
+ int offset = bytes.arrayOffset();
+
+ System.arraycopy(array, offset, array, offset + bytesRequested, bytesRequested);
+
+ freePosition -= itemSize;
+ }
+
public int bytesFree() {
return freePosition - headerSize;
}
- public Iterable<ByteBuffer> bufferIterator() {
+ public Iterable<ByteBuffer> items() {
return new Iterable<ByteBuffer>() {
@Override
public Iterator<ByteBuffer> iterator() {
diff --git a/src/test/java/io/trygvis/btree/BtreeMapTest.java b/src/test/java/io/trygvis/btree/BtreeMapTest.java
new file mode 100644
index 0000000..3c771a8
--- /dev/null
+++ b/src/test/java/io/trygvis/btree/BtreeMapTest.java
@@ -0,0 +1,45 @@
+package io.trygvis.btree;
+
+import org.junit.Test;
+
+import java.io.File;
+import java.nio.ByteBuffer;
+
+import static io.trygvis.btree.Bits.intFromBytes;
+import static io.trygvis.btree.HeapTest.Person.randomPerson;
+import static io.trygvis.btree.TestUtils.deleteFile;
+
+public class BtreeMapTest {
+
+ @Test
+ public void testBasic() throws Exception {
+ File f = new File("target/btreemap");
+ BtreeMap<Integer, HeapTest.Person> map = new BtreeMap<>(new BtreeFile(new HeapFile(128, deleteFile(f)), 4), new IntegerSerializer(), new PersonSerializer());
+
+ map.put(1, randomPerson());
+ }
+
+ private static class IntegerSerializer implements BtreeMap.Serializer<Integer> {
+ @Override
+ public byte[] toBytes(Integer integer) {
+ return Bits.toBytes(integer);
+ }
+
+ @Override
+ public Integer fromBytes(byte[] bytes) {
+ return intFromBytes(bytes);
+ }
+ }
+
+ private static class PersonSerializer implements BtreeMap.Serializer<HeapTest.Person> {
+ @Override
+ public byte[] toBytes(HeapTest.Person person) {
+ return person.toBytes();
+ }
+
+ @Override
+ public HeapTest.Person fromBytes(byte[] bytes) {
+ return HeapTest.Person.fromBytes(ByteBuffer.wrap(bytes));
+ }
+ }
+}
diff --git a/src/test/java/io/trygvis/btree/HeapPageTest.java b/src/test/java/io/trygvis/btree/HeapPageTest.java
index e845a16..b158880 100644
--- a/src/test/java/io/trygvis/btree/HeapPageTest.java
+++ b/src/test/java/io/trygvis/btree/HeapPageTest.java
@@ -3,7 +3,9 @@ package io.trygvis.btree;
import org.junit.Test;
import java.nio.ByteBuffer;
+import java.util.ArrayList;
import java.util.Iterator;
+import java.util.List;
import static io.trygvis.btree.HeapPage.*;
import static org.junit.Assert.*;
@@ -19,30 +21,43 @@ public class HeapPageTest {
HeapPage page = HeapPage.blankHeapPage(buffer);
assertEquals(pageSize - headerSize, page.bytesFree());
- int itemCount = 6;
- byte[] object = new byte[]{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf};
+ List<byte[]> objects = new ArrayList<>();
+ byte[] appendObject = new byte[]{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf};
+ int objectSize = 16;
- for (int i = 0; i < itemCount; i++) {
- page.append(object);
- assertEquals("i=" + i, pageSize - headerSize - (object.length + itemSize) * (i + 1), page.bytesFree());
+ for (int i = 0; i < 5; i++) {
+ page.append(appendObject);
+ objects.add(appendObject);
+ assertEquals("i=" + i, pageSize - headerSize - (appendObject.length + itemSize) * (i + 1), page.bytesFree());
}
- try {
- page.append(object);
- fail("Expected PageOverflowException");
- } catch (PageOverflowException e) {
- assertEquals(pageSize - headerSize - itemCount * (object.length + itemSize), e.bytesFree);
- assertEquals(object.length, e.bytesRequested);
+ byte[] prependObject = new byte[]{0xf, 0xe, 0xd, 0xc, 0xb, 0xa, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0};
+ page.prepend(prependObject);
+ objects.add(0, prependObject);
+
+// try {
+// page.append(object);
+// fail("Expected PageOverflowException");
+// } catch (PageOverflowException e) {
+// assertEquals(pageSize - headerSize - objects.size() * (object.length + objects.size()), e.bytesFree);
+// assertEquals(object.length, e.bytesRequested);
+// }
+
+ for (byte[] object : objects) {
+ for (byte b : object) {
+ System.out.print(Integer.toHexString(b));
+ }
+ System.out.println();
}
{
ByteBuffer expectedBuffer = ByteBuffer.allocate(pageSize);
- int position = pageSize - itemCount * (object.length + itemSize);
+ int position = pageSize - objects.size() * (objectSize + itemSize);
expectedBuffer.putInt(position);
expectedBuffer.position(position);
- for (int i = 0; i < itemCount; i++) {
- expectedBuffer.put(object);
- expectedBuffer.putInt(object.length);
+ for (byte[] o : objects) {
+ expectedBuffer.put(o);
+ expectedBuffer.putInt(objectSize);
}
assertEquals(pageSize, expectedBuffer.position());
@@ -52,11 +67,11 @@ public class HeapPageTest {
}
{
- Iterator<ByteBuffer> it = page.bufferIterator().iterator();
- for (int i = 0; i < itemCount; i++) {
+ Iterator<ByteBuffer> it = page.items().iterator();
+ for (byte[] o : objects) {
assertTrue(it.hasNext());
ByteBuffer bb = it.next();
- assertArrayEquals(object, toArray(bb));
+ assertArrayEquals(o, toArray(bb));
}
assertFalse(it.hasNext());
}
diff --git a/src/test/java/io/trygvis/btree/HeapTest.java b/src/test/java/io/trygvis/btree/HeapTest.java
index 1d724f4..48a1463 100644
--- a/src/test/java/io/trygvis/btree/HeapTest.java
+++ b/src/test/java/io/trygvis/btree/HeapTest.java
@@ -4,6 +4,8 @@ import org.junit.Test;
import java.io.File;
import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.List;
import java.util.Random;
import static io.trygvis.btree.HeapTest.Person.randomPerson;
@@ -14,6 +16,8 @@ public class HeapTest {
@Test
public void testHeap() throws Exception {
+ List<Person> persons = new ArrayList<Person>();
+
File f = new File("target/heapTest");
HeapFile file = new HeapFile(128, deleteFile(f));
@@ -23,6 +27,7 @@ public class HeapTest {
int pageNo = 0;
for (int i = 0; i < 10; i++) {
Person p = randomPerson();
+ persons.add(p);
byte[] bytes = p.toBytes();
@@ -47,13 +52,15 @@ public class HeapTest {
System.out.println("file.pageCount() = " + file.pageCount());
+ int counter = 0;
for (int i = 0; i < file.pageCount(); i++) {
System.out.println("page #" + i);
page = file.loadPage(i);
- for (ByteBuffer buffer : page.bufferIterator()) {
+ for (ByteBuffer buffer : page.items()) {
Person p = Person.fromBytes(buffer);
System.out.println("p = " + p);
+ assertEquals(persons.get(counter++), p);
}
}
}
@@ -91,6 +98,23 @@ public class HeapTest {
'}';
}
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) return true;
+ if (!(o instanceof Person)) return false;
+
+ Person person = (Person) o;
+
+ return age == person.age && name.equals(person.name);
+ }
+
+ @Override
+ public int hashCode() {
+ int result = name.hashCode();
+ result = 31 * result + age;
+ return result;
+ }
+
private final static Random r = new Random(0);
private final static String[] names = new String[]{
"Lukas", "Emil", "Mathias", "Jonas", "Aleksander", "William", "Oskar", "Magnus", "Markus", "Oliver",
generated by cgit v1.2.3 (git 2.46.0) at 2024-12-22 16:41:59 +0000