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提交 0cd81ddb authored 作者: Thomas Mueller Graf's avatar Thomas Mueller Graf
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File systems: the compressed in-memory file systems now compress better

上级 861aec17
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h2/src/docsrc/html/changelog.html
浏览文件 @ 0cd81ddb
......@@ -97,6 +97,8 @@ Change Log
</li>
<li>File system nioMemFS: support concurrent reads.
</li>
<li>File systems: the compressed in-memory file systems now compress better.
</li>
<li>LIRS cache: improved hit rate because now added entries get hot if they
were in the non-resident part of the cache before.
</li>
......
h2/src/main/org/h2/store/fs/FilePathMem.java
浏览文件 @ 0cd81ddb
......@@ -88,7 +88,10 @@ public class FilePathMem extends FilePath {
return;
}
synchronized (MEMORY_FILES) {
MEMORY_FILES.remove(name);
FileMemData old = MEMORY_FILES.remove(name);
if (old != null) {
old.truncate(0);
}
}
}
......@@ -399,6 +402,7 @@ class FileMemData {
new Cache<CompressItem, CompressItem>(CACHE_SIZE);
private String name;
private final int id;
private final boolean compress;
private long length;
private byte[][] data;
......@@ -416,11 +420,16 @@ class FileMemData {
FileMemData(String name, boolean compress) {
this.name = name;
this.id = name.hashCode();
this.compress = compress;
data = new byte[0][];
lastModified = System.currentTimeMillis();
}
int getId() {
return id;
}
/**
* Lock the file in exclusive mode if possible.
*
......@@ -477,20 +486,25 @@ class FileMemData {
return false;
}
CompressItem c = (CompressItem) eldest.getKey();
compress(c.data, c.page);
c.file.compress(c.page, c.data);
return true;
}
}
/**
* Represents a compressed item.
* Points to a block of bytes that needs to be compressed.
*/
static class CompressItem {
/**
* The file data.
* The file.
*/
FileMemData file;
/**
* The data array.
*/
byte[][] data;
byte[] data;
/**
* The page to compress.
......@@ -499,30 +513,31 @@ class FileMemData {
@Override
public int hashCode() {
return page;
return page ^ file.getId();
}
@Override
public boolean equals(Object o) {
if (o instanceof CompressItem) {
CompressItem c = (CompressItem) o;
return c.data == data && c.page == page;
return c.page == page && c.file == file;
}
return false;
}
}
private static void compressLater(byte[][] data, int page) {
private void compressLater(int page) {
CompressItem c = new CompressItem();
c.data = data;
c.file = this;
c.page = page;
c.data = data[page];
synchronized (LZF) {
COMPRESS_LATER.put(c, c);
}
}
private static void expand(byte[][] data, int page) {
private void expand(int page) {
byte[] d = data[page];
if (d.length == BLOCK_SIZE) {
return;
......@@ -542,14 +557,26 @@ class FileMemData {
* @param data the page array
* @param page which page to compress
*/
static void compress(byte[][] data, int page) {
byte[] d = data[page];
void compress(int page, byte[] old) {
byte[][] array = data;
if (page >= array.length) {
return;
}
byte[] d = array[page];
if (d != old) {
return;
}
synchronized (LZF) {
int len = LZF.compress(d, BLOCK_SIZE, BUFFER, 0);
if (len <= BLOCK_SIZE) {
d = new byte[len];
System.arraycopy(BUFFER, 0, d, 0, len);
data[page] = d;
// maybe data was changed in the meantime
byte[] o = array[page];
if (o != old) {
return;
}
array[page] = d;
}
}
}
......@@ -585,13 +612,13 @@ class FileMemData {
long end = MathUtils.roundUpLong(newLength, BLOCK_SIZE);
if (end != newLength) {
int lastPage = (int) (newLength >>> BLOCK_SIZE_SHIFT);
expand(data, lastPage);
expand(lastPage);
byte[] d = data[lastPage];
for (int i = (int) (newLength & BLOCK_SIZE_MASK); i < BLOCK_SIZE; i++) {
d[i] = 0;
}
if (compress) {
compressLater(data, lastPage);
compressLater(lastPage);
}
}
}
......@@ -632,7 +659,7 @@ class FileMemData {
while (len > 0) {
int l = (int) Math.min(len, BLOCK_SIZE - (pos & BLOCK_SIZE_MASK));
int page = (int) (pos >>> BLOCK_SIZE_SHIFT);
expand(data, page);
expand(page);
byte[] block = data[page];
int blockOffset = (int) (pos & BLOCK_SIZE_MASK);
if (write) {
......@@ -641,7 +668,7 @@ class FileMemData {
System.arraycopy(block, blockOffset, b, off, l);
}
if (compress) {
compressLater(data, page);
compressLater(page);
}
off += l;
pos += l;
......
h2/src/main/org/h2/store/fs/FilePathNioMem.java
浏览文件 @ 0cd81ddb
......@@ -408,6 +408,7 @@ class FileNioMemData {
new Cache<CompressItem, CompressItem>(CACHE_SIZE);
private String name;
private final int id;
private final boolean compress;
private long length;
private ByteBuffer[] data;
......@@ -425,11 +426,16 @@ class FileNioMemData {
FileNioMemData(String name, boolean compress) {
this.name = name;
this.id = name.hashCode();
this.compress = compress;
data = new ByteBuffer[0];
lastModified = System.currentTimeMillis();
}
int getId() {
return id;
}
/**
* Lock the file in exclusive mode if possible.
*
......@@ -486,7 +492,7 @@ class FileNioMemData {
return false;
}
CompressItem c = (CompressItem) eldest.getKey();
compress(c.data, c.page);
c.data.compress(c.page);
return true;
}
}
......@@ -499,7 +505,7 @@ class FileNioMemData {
/**
* The file data.
*/
ByteBuffer[] data;
FileNioMemData data;
/**
* The page to compress.
......@@ -508,7 +514,7 @@ class FileNioMemData {
@Override
public int hashCode() {
return page;
return page ^ data.getId();
}
@Override
......@@ -522,16 +528,16 @@ class FileNioMemData {
}
private static void compressLater(ByteBuffer[] data, int page) {
private void compressLater(int page) {
CompressItem c = new CompressItem();
c.data = data;
c.data = this;
c.page = page;
synchronized (LZF) {
COMPRESS_LATER.put(c, c);
}
}
private static void expand(ByteBuffer[] data, int page) {
private void expand(int page) {
ByteBuffer d = data[page];
if (d.capacity() == BLOCK_SIZE) {
return;
......@@ -552,7 +558,7 @@ class FileNioMemData {
* @param data the page array
* @param page which page to compress
*/
static void compress(ByteBuffer[] data, int page) {
void compress(int page) {
ByteBuffer d = data[page];
synchronized (LZF) {
int len = LZF.compress(d, 0, BUFFER, 0);
......@@ -593,13 +599,13 @@ class FileNioMemData {
long end = MathUtils.roundUpLong(newLength, BLOCK_SIZE);
if (end != newLength) {
int lastPage = (int) (newLength >>> BLOCK_SIZE_SHIFT);
expand(data, lastPage);
expand(lastPage);
ByteBuffer d = data[lastPage];
for (int i = (int) (newLength & BLOCK_SIZE_MASK); i < BLOCK_SIZE; i++) {
d.put(i, (byte) 0);
}
if (compress) {
compressLater(data, lastPage);
compressLater(lastPage);
}
}
}
......@@ -640,7 +646,7 @@ class FileNioMemData {
while (len > 0) {
int l = (int) Math.min(len, BLOCK_SIZE - (pos & BLOCK_SIZE_MASK));
int page = (int) (pos >>> BLOCK_SIZE_SHIFT);
expand(data, page);
expand(page);
ByteBuffer block = data[page];
int blockOffset = (int) (pos & BLOCK_SIZE_MASK);
if (write) {
......@@ -661,7 +667,7 @@ class FileNioMemData {
b.position(oldPosition);
}
if (compress) {
compressLater(data, page);
compressLater(page);
}
off += l;
pos += l;
......
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