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uses ConcurrentHashMap to increase performance #1

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65 changes: 31 additions & 34 deletions bigmap/src/main/java/com/ctriposs/bigmap/page/MappedPageFactoryImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentHashMap;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
Expand Down Expand Up @@ -38,7 +39,7 @@ public class MappedPageFactoryImpl implements IMappedPageFactory {
public static final String PAGE_FILE_NAME = "page";
public static final String PAGE_FILE_SUFFIX = ".dat";

private Map<Long, MappedPageImpl> cache;
private ConcurrentHashMap<Long, MappedPageImpl> cache;

public MappedPageFactoryImpl(int pageSize, String pageDir) {
this.pageSize = pageSize;
Expand All @@ -48,44 +49,40 @@ public MappedPageFactoryImpl(int pageSize, String pageDir) {
pageDirFile.mkdirs();
}
if (!this.pageDir.endsWith(File.separator)) {
this.pageDir += File.separator;
this.pageDir += File.separator;
}
this.pageFile = this.pageDir + PAGE_FILE_NAME + "-";
this.cache = new HashMap<Long, MappedPageImpl>();
this.cache = new ConcurrentHashMap<Long, MappedPageImpl>();
}

public IMappedPage acquirePage(long index) throws IOException {
MappedPageImpl mpi = cache.get(index);
if (mpi == null) { // not in cache, need to create one
synchronized(cache) { // lock the map
mpi = cache.get(index); // double check
if (mpi == null) {
RandomAccessFile raf = null;
FileChannel channel = null;
try {
String fileName = this.getFileNameByIndex(index);
raf = new RandomAccessFile(fileName, "rw");
channel = raf.getChannel();
MappedByteBuffer mbb = channel.map(READ_WRITE, 0, this.pageSize);
mpi = new MappedPageImpl(mbb, fileName, index);
cache.put(index, mpi);
if (logger.isDebugEnabled()) {
logger.debug("Mapped page for " + fileName + " was just created and cached.");
}
} finally {
if (channel != null) channel.close();
if (raf != null) raf.close();
}
}
}
} else {
if (logger.isDebugEnabled()) {
logger.debug("Hit mapped page " + mpi.getPageFile() + " in cache.");
}
}

return mpi;
}
MappedPageImpl mpi = cache.get(index);
if (mpi == null) { // not in cache, need to create one
RandomAccessFile raf = null;
FileChannel channel = null;
try {
String fileName = this.getFileNameByIndex(index);
raf = new RandomAccessFile(fileName, "rw");
channel = raf.getChannel();
MappedByteBuffer mbb = channel.map(READ_WRITE, 0, this.pageSize);
mpi = new MappedPageImpl(mbb, fileName, index);
MappedPageImpl prev = cache.putIfAbsent(index, mpi);
if(prev != null)
mpi=prev;
if (logger.isDebugEnabled()) {
logger.debug("Mapped page for " + fileName + " was just created and cached.");
}
} finally {
if (channel != null) channel.close();
if (raf != null) raf.close();
}
} else {
if (logger.isDebugEnabled()) {
logger.debug("Hit mapped page " + mpi.getPageFile() + " in cache.");
}
}
return mpi;
}

private String getFileNameByIndex(long index) {
return this.pageFile + index + PAGE_FILE_SUFFIX;
Expand Down