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提交 582ca70b authored 作者: Thomas Mueller's avatar Thomas Mueller
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A persistent tree map (work in progress).

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h2/src/tools/org/h2/dev/store/btree/BtreeMap.java
浏览文件 @ 582ca70b
......@@ -7,6 +7,7 @@
package org.h2.dev.store.btree;
import java.util.Iterator;
import java.util.TreeMap;
/**
* A stored map.
......@@ -16,35 +17,23 @@ import java.util.Iterator;
*/
public class BtreeMap<K, V> {
private final BtreeMapStore store;
private final int id;
private final String name;
private final DataType keyType;
private final DataType valueType;
private final long createVersion;
private final TreeMap<Long, Page> oldRoots = new TreeMap<Long, Page>();
private BtreeMapStore store;
private Page root;
private boolean readOnly;
private BtreeMap(BtreeMapStore store, int id, String name, DataType keyType, DataType valueType) {
BtreeMap(BtreeMapStore store, int id, String name, DataType keyType, DataType valueType, long createVersion) {
this.store = store;
this.id = id;
this.name = name;
this.keyType = keyType;
this.valueType = valueType;
}
/**
* Open a map.
*
* @param <K> the key type
* @param <V> the value type
* @param store the tree store
* @param id the map id
* @param name the name of the map
* @param keyClass the key class
* @param valueClass the value class
* @return the map
*/
static <K, V> BtreeMap<K, V> open(BtreeMapStore store, int id, String name, DataType keyType, DataType valueType) {
return new BtreeMap<K, V>(store, id, name, keyType, valueType);
this.createVersion = createVersion;
}
/**
......@@ -54,8 +43,10 @@ public class BtreeMap<K, V> {
* @param data the value
*/
public void put(K key, V data) {
markChanged();
root = Page.put(this, root, key, data);
checkWrite();
Page oldRoot = root;
root = Page.put(this, root, store.getCurrentVersion(), key, data);
markChanged(oldRoot);
}
/**
......@@ -66,12 +57,17 @@ public class BtreeMap<K, V> {
*/
@SuppressWarnings("unchecked")
public V get(K key) {
checkOpen();
if (root == null) {
return null;
}
return (V) root.find(key);
}
public boolean containsKey(K key) {
return get(key) != null;
}
/**
* Get the page for the given value.
*
......@@ -89,19 +85,32 @@ public class BtreeMap<K, V> {
* Remove all entries.
*/
public void clear() {
checkWrite();
if (root != null) {
markChanged();
Page oldRoot = root;
root.removeAllRecursive();
root = null;
markChanged(oldRoot);
}
}
/**
* Remove all entries, and remove the map.
* Remove all entries, and remove the map. The map becomes invalid.
*/
public void remove() {
clear();
checkWrite();
if (root != null) {
root.removeAllRecursive();
}
store.removeMap(id);
oldRoots.clear();
root = null;
store = null;
readOnly = true;
}
public boolean isClosed() {
return store == null;
}
/**
......@@ -110,25 +119,23 @@ public class BtreeMap<K, V> {
* @param key the key
*/
public void remove(K key) {
checkWrite();
if (root != null) {
markChanged();
root = Page.remove(root, key);
Page oldRoot = root;
root = Page.remove(root, store.getCurrentVersion(), key);
markChanged(oldRoot);
}
}
/**
* Was this map changed.
*
* @return true if yes
*/
boolean isChanged() {
return root != null && root.getPos() < 0;
private void markChanged(Page oldRoot) {
if (oldRoot != root) {
oldRoots.put(store.getCurrentVersion(), oldRoot);
store.markChanged(this);
}
private void markChanged() {
if (!isChanged()) {
store.markChanged(name, this);
}
public boolean hasUnsavedChanges() {
return oldRoots.size() > 0;
}
/**
......@@ -160,20 +167,6 @@ public class BtreeMap<K, V> {
return valueType;
}
long getTransaction() {
return store.getTransaction();
}
/**
* Register a page and get the next temporary page id.
*
* @param p the new page
* @return the page id
*/
long registerTempPage(Page p) {
return store.registerTempPage(p);
}
/**
* Read a page.
*
......@@ -184,22 +177,13 @@ public class BtreeMap<K, V> {
return store.readPage(this, pos);
}
/**
* Remove a page.
*
* @param pos the position of the page
*/
void removePage(long pos) {
store.removePage(pos);
}
/**
* Set the position of the root page.
*
* @param rootPos the position
* @param rootPos the position, 0 for empty
*/
void setRootPos(long rootPos) {
root = readPage(rootPos);
root = rootPos == 0 ? null : readPage(rootPos);
}
/**
......@@ -209,6 +193,7 @@ public class BtreeMap<K, V> {
* @return the iterator
*/
public Iterator<K> keyIterator(K from) {
checkOpen();
return new Cursor<K>(root, from);
}
......@@ -238,4 +223,78 @@ public class BtreeMap<K, V> {
return id;
}
void rollbackTo(long version) {
checkWrite();
if (version <= createVersion) {
remove();
} else {
// iterating in ascending order, and pick the last version -
// this is not terribly efficient if there are many versions
// but it is a simple algorithm
Long newestOldVersion = null;
for (Iterator<Long> it = oldRoots.keySet().iterator(); it.hasNext();) {
Long x = it.next();
if (x >= version) {
if (newestOldVersion == null) {
newestOldVersion = x;
root = oldRoots.get(x);
}
it.remove();
}
}
}
}
public void setReadOnly(boolean readOnly) {
this.readOnly = readOnly;
}
public boolean isReadOnly() {
return readOnly;
}
private void checkOpen() {
if (store == null) {
throw new IllegalStateException("This map is closed");
}
}
private void checkWrite() {
if (readOnly) {
checkOpen();
throw new IllegalStateException("This map is read-only");
}
}
public String toString() {
StringBuilder buff = new StringBuilder();
buff.append("map:").append(name);
if (readOnly) {
buff.append(" readOnly");
}
if (store == null) {
buff.append(" closed");
}
return buff.toString();
}
public void close() {
readOnly = true;
store = null;
oldRoots.clear();
root = null;
}
public int hashCode() {
return id;
}
public boolean equals(Object o) {
return this == o;
}
long getCreatedVersion() {
return createVersion;
}
}
h2/src/tools/org/h2/dev/store/btree/BtreeMapStore.java
浏览文件 @ 582ca70b
......@@ -28,43 +28,35 @@ import org.h2.util.StringUtils;
/*
file format:
header
header
File format:
header: 4096 bytes
header: 4096 bytes
[ chunk ] *
(there are two headers for security)
header:
# H3 store #
blockSize=4096
chunk:
1 byte: 'c'
4 bytes: length
4 bytes: chunk id (an incrementing number)
8 bytes: metaRootPos
data ...
Limits: there are at most 67 million chunks (each chunk is at most 2 GB large).
TODO:
- use partial page checksums
- rollback feature
- support range deletes
- keep page type (leaf/node) in pos to speed up large deletes
- floating header (avoid duplicate header)
for each chunk, store chunk (a counter)
for each page, store chunk id and offset to root
for each chunk, store position of expected next chunks
- support reading metadata to copy all data,
- support quota (per map, per storage)
- support r-tree, kd-tree
- map ids should be per chunk, to ensure uniqueness
- support fast range deletes
- support custom pager for r-tree, kd-tree
- need an 'end of chunk' marker to verify all data is written
- truncate the file if it is empty
- ability to diff / merge versions
- check if range reads would be faster
- map.getVersion and opening old maps read-only
- limited support for writing to old versions (branches)
- Serializer instead of DataType, (serialize, deserialize)
- implement Map interface
- maybe rename to MVStore, MVMap, TestMVStore
- implement Map interface
- atomic operations (test-and-set)
- support back ground writes (store old version)
- re-use map ids that were not used for a very long time
- file header could be a regular chunk, end of file the second
- possibly split chunk data into immutable and mutable
- reduce minimum chunk size, speed up very small transactions
*/
......@@ -93,18 +85,29 @@ public class BtreeMapStore {
private int lastChunkId;
private HashMap<Integer, Chunk> chunks = New.hashMap();
// TODO use bit set, and integer instead of long
/**
* The map of temporarily freed entries in the chunks. The key is the
* unsaved version, the value is the map of chunks. The maps of chunks
* contains the number of freed entries per chunk.
*/
private HashMap<Long, HashMap<Integer, Chunk>> freedChunks = New.hashMap();
private BtreeMap<String, String> meta;
private HashMap<String, BtreeMap<?, ?>> maps = New.hashMap();
private HashMap<String, BtreeMap<?, ?>> mapsChanged = New.hashMap();
private int mapIdMin;
private BitSet mapIds = new BitSet();
// TODO use an int instead? (with rollover to 0)
private long transaction;
/**
* The set of maps with potentially unsaved changes.
*/
private HashMap<Integer, BtreeMap<?, ?>> mapsChanged = New.hashMap();
private int lastMapId;
private boolean reuseSpace = true;
private int retainChunk = -1;
private Compressor compressor = new CompressLZF();
private long currentVersion;
private BtreeMapStore(String fileName, DataTypeFactory typeFactory) {
this.fileName = fileName;
this.typeFactory = typeFactory;
......@@ -149,41 +152,62 @@ public class BtreeMapStore {
if (m == null) {
String identifier = meta.get("map." + name);
int id;
String root;
long root;
long createVersion;
if (identifier == null) {
id = nextMapId();
String types = id + "/" + keyType.asString() + "/" + valueType.asString();
id = ++lastMapId;
String types = id + "/" + currentVersion + "/" + keyType.asString() + "/" + valueType.asString();
meta.put("map." + name, types);
root = null;
root = 0;
createVersion = currentVersion;
} else {
String types = meta.get("map." + name);
String[] idTypeList = StringUtils.arraySplit(types, '/', false);
id = Integer.parseInt(idTypeList[0]);
keyType = getDataType(idTypeList[1]);
valueType = getDataType(idTypeList[2]);
root = meta.get("root." + id);
createVersion = Long.parseLong(idTypeList[1]);
keyType = getDataType(idTypeList[2]);
valueType = getDataType(idTypeList[3]);
String r = meta.get("root." + id);
root = r == null ? 0 : Long.parseLong(r);
}
m = BtreeMap.open(this, id, name, keyType, valueType);
m = new BtreeMap<K, V>(this, id, name, keyType, valueType, createVersion);
maps.put(name, m);
if (root != null && !"0".equals(root)) {
m.setRootPos(Long.parseLong(root));
}
m.setRootPos(root);
}
return m;
}
private int nextMapId() {
int result;
while (true) {
result = mapIds.nextClearBit(mapIdMin);
mapIds.set(result);
// TODO need to check in oldest
if (meta.get("root." + result) == null) {
break;
/**
* Get the metadata map. It contains the following entries:
*
* <pre>
* map.{name} = {mapId}/{keyType}/{valueType}
* root.{mapId} = {rootPos}
* chunk.{chunkId} = {chunkData}
* </pre>
*
* @return the metadata map
*/
public BtreeMap<String, String> getMetaMap() {
return meta;
}
private BtreeMap<String, String> getMetaMap(long version) {
Chunk c = getChunkForVersion(version);
BtreeMap<String, String> oldMeta = new BtreeMap<String, String>(this, 0, "old-meta", STRING_TYPE, STRING_TYPE, 0);
oldMeta.setRootPos(c.metaRootPos);
return oldMeta;
}
private Chunk getChunkForVersion(long version) {
for (int chunkId = lastChunkId;; chunkId--) {
Chunk x = chunks.get(chunkId);
if (x == null || x.version < version) {
return null;
} else if (x.version == version) {
return x;
}
}
mapIdMin = result;
return result;
}
/**
......@@ -203,8 +227,8 @@ public class BtreeMapStore {
}
void removeMap(int id) {
mapIds.clear(id);
mapIdMin = Math.min(id, mapIdMin);
BtreeMap<?, ?> m = maps.remove(id);
mapsChanged.remove(m);
}
private DataType getDataType(Class<?> clazz) {
......@@ -229,19 +253,16 @@ public class BtreeMapStore {
}
/**
* Mark a map as changed.
* Mark a map as changed (containing unsaved changes).
*
* @param name the map name
* @param map the map
*/
void markChanged(String name, BtreeMap<?, ?> map) {
if (map != meta) {
mapsChanged.put(name, map);
}
void markChanged(BtreeMap<?, ?> map) {
mapsChanged.put(map.getId(), map);
}
private void open() {
meta = BtreeMap.open(this, 0, "meta", STRING_TYPE, STRING_TYPE);
meta = new BtreeMap<String, String>(this, 0, "meta", STRING_TYPE, STRING_TYPE, 0);
FileUtils.createDirectories(FileUtils.getParent(fileName));
try {
log("file open");
......@@ -287,8 +308,8 @@ public class BtreeMapStore {
"versionWrite:1\n" +
"blockSize:" + blockSize + "\n" +
"rootChunk:" + rootChunkStart + "\n" +
"lastMapId:" + mapIdMin + "\n" +
"transaction:" + transaction + "\n").getBytes("UTF-8"));
"lastMapId:" + lastMapId + "\n" +
"version:" + currentVersion + "\n").getBytes("UTF-8"));
file.position(0);
file.write(header);
file.position(blockSize);
......@@ -307,8 +328,8 @@ public class BtreeMapStore {
Properties prop = new Properties();
prop.load(new StringReader(new String(header, "UTF-8")));
rootChunkStart = Long.parseLong(prop.get("rootChunk").toString());
transaction = Long.parseLong(prop.get("transaction").toString());
mapIdMin = Integer.parseInt(prop.get("lastMapId").toString());
currentVersion = Long.parseLong(prop.get("version").toString());
lastMapId = Integer.parseInt(prop.get("lastMapId").toString());
} catch (Exception e) {
throw convert(e);
}
......@@ -319,13 +340,23 @@ public class BtreeMapStore {
}
/**
* Close the file. Uncommitted changes are ignored.
* Close the file. Uncommitted changes are ignored, and all open maps are closed.
*/
public void close() {
if (file != null) {
try {
log("file close");
file.close();
for (BtreeMap<?, ?> m : New.arrayList(maps.values())) {
m.close();
}
temp.clear();
meta = null;
compressor = null;
chunks.clear();
cache.clear();
maps.clear();
mapsChanged.clear();
} catch (Exception e) {
file = null;
throw convert(e);
......@@ -334,30 +365,30 @@ public class BtreeMapStore {
}
private Chunk getChunk(long pos) {
return chunks.get(Page.getChunkId(pos));
return chunks.get(DataUtils.getChunkId(pos));
}
private long getFilePosition(long pos) {
Chunk c = getChunk(pos);
if (c == null) {
throw new RuntimeException("Chunk " + Page.getChunkId(pos) + " not found");
throw new RuntimeException("Chunk " + DataUtils.getChunkId(pos) + " not found");
}
long filePos = c.start;
filePos += Page.getOffset(pos);
filePos += DataUtils.getOffset(pos);
return filePos;
}
/**
* Commit all changes and persist them to disk.
* Commit all changes and persist them to disk. This method does nothing if
* there are no unsaved changes.
*
* @return the transaction id
* @return the new version
*/
public long store() {
if (!meta.isChanged() && mapsChanged.size() == 0) {
// TODO truncate file if empty
return transaction;
if (!hasUnsavedChanges()) {
return currentVersion;
}
long trans = commit();
long newVersion = commit();
int chunkId = ++lastChunkId;
......@@ -366,16 +397,19 @@ public class BtreeMapStore {
c.liveCount = Integer.MAX_VALUE;
c.start = Long.MAX_VALUE;
c.length = Long.MAX_VALUE;
c.version = currentVersion;
chunks.put(c.id, c);
meta.put("chunk." + c.id, c.toString());
applyFreedChunks();
ArrayList<Integer> removedChunks = New.arrayList();
for (Chunk x : chunks.values()) {
if (x.liveCount == 0) {
if (x.liveCount == 0 && (retainChunk == -1 || x.id < retainChunk)) {
meta.remove("chunk." + x.id);
removedChunks.add(x.id);
} else {
meta.put("chunk." + x.id, x.toString());
}
applyFreedChunks();
}
for (int x : removedChunks) {
chunks.remove(x);
......@@ -383,6 +417,9 @@ public class BtreeMapStore {
int count = 0;
int maxLength = 1 + 4 + 4 + 8;
for (BtreeMap<?, ?> m : mapsChanged.values()) {
if (m == meta || !m.hasUnsavedChanges()) {
continue;
}
Page p = m.getRoot();
if (p != null) {
maxLength += p.getMaxLengthTempRecursive();
......@@ -402,6 +439,9 @@ public class BtreeMapStore {
buff.putInt(0);
buff.putLong(0);
for (BtreeMap<?, ?> m : mapsChanged.values()) {
if (m == meta || !m.hasUnsavedChanges()) {
continue;
}
Page p = m.getRoot();
if (p != null) {
long root = p.writeTempRecursive(buff, chunkId);
......@@ -434,19 +474,38 @@ public class BtreeMapStore {
}
rootChunkStart = filePos;
writeHeader();
mapsChanged.clear();
temp.clear();
tempPageId = 0;
revertTemp();
// update the start position and length
c.start = filePos;
c.length = length;
meta.put("chunk." + c.id, c.toString());
return trans;
return newVersion;
}
private void applyFreedChunks() {
// apply liveCount changes
for (HashMap<Integer, Chunk> freed : freedChunks.values()) {
for (Chunk f : freed.values()) {
Chunk c = chunks.get(f.id);
c.liveCount += f.liveCount;
}
}
freedChunks.clear();
}
private long allocateChunk(long length) {
if (!reuseSpace) {
int min = 0;
for (Chunk c : chunks.values()) {
if (c.start == Long.MAX_VALUE) {
continue;
}
int last = (int) ((c.start + c.length) / blockSize);
min = Math.max(min, last + 1);
}
return min * blockSize;
}
BitSet set = new BitSet();
set.set(0);
set.set(1);
......@@ -476,15 +535,6 @@ public class BtreeMapStore {
return set.size() * blockSize;
}
/**
* Get the current transaction number.
*
* @return the transaction number
*/
long getTransaction() {
return transaction;
}
/**
* Register a page and get the next temporary page id.
*
......@@ -498,12 +548,29 @@ public class BtreeMapStore {
}
/**
* Commit the current transaction.
* Commit the changes, incrementing the current version.
*
* @return the transaction id
* @return the new version
*/
public long commit() {
return ++transaction;
return ++currentVersion;
}
/**
* Check whether there are any unsaved changes.
*
* @return if there are any changes
*/
public boolean hasUnsavedChanges() {
if (mapsChanged.size() == 0) {
return false;
}
for (BtreeMap<?, ?> m : mapsChanged.values()) {
if (m.hasUnsavedChanges()) {
return true;
}
}
return false;
}
private Chunk readChunkHeader(long start) {
......@@ -579,9 +646,10 @@ public class BtreeMapStore {
it.remove();
}
}
// TODO not needed - we already have the chunk object
Chunk header = readChunkHeader(move.start);
log(" meta:" + move.id + "/" + header.metaRootPos + " start: " + move.start);
BtreeMap<String, String> oldMeta = BtreeMap.open(this, 0, "old-meta", STRING_TYPE, STRING_TYPE);
BtreeMap<String, String> oldMeta = new BtreeMap<String, String>(this, 0, "old-meta", STRING_TYPE, STRING_TYPE, 0);
oldMeta.setRootPos(header.metaRootPos);
Iterator<String> it = oldMeta.keyIterator(null);
ArrayList<Integer> oldChunks = New.arrayList();
......@@ -606,10 +674,10 @@ public class BtreeMapStore {
}
String[] idTypesList = StringUtils.arraySplit(s, '/', false);
int id = Integer.parseInt(idTypesList[0]);
DataType kt = getDataType(idTypesList[1]);
DataType vt = getDataType(idTypesList[2]);
DataType kt = getDataType(idTypesList[2]);
DataType vt = getDataType(idTypesList[3]);
long oldDataRoot = Long.parseLong(oldMeta.get("root." + id));
BtreeMap<?, ?> oldData = BtreeMap.open(this, id, "old-" + k, kt, vt);
BtreeMap<?, ?> oldData = new BtreeMap<Object, Object>(this, id, "old-" + k, kt, vt, 0);
if (oldDataRoot == 0) {
// no rows
} else {
......@@ -668,17 +736,28 @@ public class BtreeMapStore {
* @param pos the position of the page
*/
void removePage(long pos) {
// we need to keep temporary pages,
// to support reading old versions and rollback
if (pos > 0) {
// this could result in a cache miss
// if the operation is rolled back,
// but we don't optimize for rollback
cache.remove(pos);
if (getChunk(pos).liveCount == 0) {
Chunk c = getChunk(pos);
if (c.liveCount == 0) {
throw new RuntimeException("Negative live count: " + pos);
}
getChunk(pos).liveCount--;
} else {
temp.remove(pos);
if (temp.size() == 0) {
tempPageId = 0;
HashMap<Integer, Chunk>freed = freedChunks.get(currentVersion);
if (freed == null) {
freed = New.hashMap();
freedChunks.put(currentVersion, freed);
}
Chunk f = freed.get(c.id);
if (f == null) {
f = new Chunk(c.id);
freed.put(c.id, f);
}
f.liveCount--;
}
}
......@@ -708,4 +787,131 @@ public class BtreeMapStore {
this.compressor = compressor;
}
public boolean getReuseSpace() {
return reuseSpace;
}
public void setReuseSpace(boolean reuseSpace) {
this.reuseSpace = reuseSpace;
}
public int getRetainChunk() {
return retainChunk;
}
/**
* Which chunk to retain. If not set, old chunks are re-used as soon as
* possible, which may make it impossible to roll back beyond a save
* operation, or read a older version before.
* <p>
* This setting is not persisted.
*
* @param retainChunk the earliest chunk to retain (0 to retain all chunks,
* -1 to re-use space as early as possible)
*/
public void setRetainChunk(int retainChunk) {
this.retainChunk = retainChunk;
}
public boolean isKnownVersion(long version) {
if (version > currentVersion || version < 0) {
return false;
}
if (chunks.size() == 0) {
return true;
}
Chunk c = getChunkForVersion(version);
if (c == null) {
return false;
}
BtreeMap<String, String> oldMeta = getMetaMap(version);
if (oldMeta == null) {
return false;
}
for (Iterator<String> it = oldMeta.keyIterator("chunk."); it.hasNext();) {
String chunkKey = it.next();
if (!chunkKey.startsWith("chunk.")) {
break;
}
if (!meta.containsKey(chunkKey)) {
return false;
}
}
return true;
}
/**
* Revert to the given version. All later changes (stored or not) are
* forgotten. All maps that were created later are closed. A rollback to
* a version before the last stored version is immediately persisted.
*
* @param version the version to keep
*/
public void rollbackTo(long version) {
if (!isKnownVersion(version)) {
throw new IllegalArgumentException("Unknown version: " + version);
}
// TODO could remove newer temporary pages on rollback
for (BtreeMap<?, ?> m : mapsChanged.values()) {
m.rollbackTo(version);
}
for (long v = currentVersion; v >= version; v--) {
if (freedChunks.size() == 0) {
break;
}
freedChunks.remove(v);
}
meta.rollbackTo(version);
boolean loadFromFile = false;
Chunk last = chunks.get(lastChunkId);
if (last != null) {
if (last.version >= version) {
revertTemp();
}
if (last.version > version) {
loadFromFile = true;
while (last != null && last.version > version) {
chunks.remove(lastChunkId);
lastChunkId--;
last = chunks.get(lastChunkId);
}
rootChunkStart = last.start;
writeHeader();
readHeader();
readMeta();
}
}
for (BtreeMap<?, ?> m : maps.values()) {
if (m.getCreatedVersion() > version) {
m.close();
removeMap(m.getId());
} else {
if (loadFromFile) {
String r = meta.get("root." + m.getId());
long root = r == null ? 0 : Long.parseLong(r);
m.setRootPos(root);
}
}
}
this.currentVersion = version;
}
private void revertTemp() {
freedChunks.clear();
mapsChanged.clear();
temp.clear();
tempPageId = 0;
}
/**
* Get the current version of the store. When a new store is created, the
* version is 0. For each commit, it is incremented by one if there was a
* change.
*
* @return the version
*/
public long getCurrentVersion() {
return currentVersion;
}
}
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