/*
* (non-Javadoc)
* @see de.tuberlin.dima.minidb.io.ResourceManager#reserveNewPage(byte[])
*/
@Override
public CacheableData reserveNewPage(byte[] ioBuffer) throws IOException, PageFormatException {
// create disk representation of data
byte[] diskCopy = new byte[this.pageSize.getNumberOfBytes()];
// copy current contents of buffer to disk array
System.arraycopy(ioBuffer, 0, diskCopy, 0, ioBuffer.length);
TablePage page =
AbstractExtensionFactory.getExtensionFactory()
.initTablePage(this.schema, ioBuffer, this.pageNumber++);
this.diskBuffer.add(diskCopy);
return page;
}
/*
* (non-Javadoc)
* @see de.tuberlin.dima.minidb.io.ResourceManager#readPageFromResource(byte[], int)
*/
@Override
public CacheableData readPageFromResource(byte[] buffer, int pageNumber) throws IOException {
// add the request to the list of read requests
this.readRequests.add(pageNumber);
// check if thread is different than the creator
if (Thread.currentThread() == this.creator) {
throw new IOException(readingSeparateThread);
}
// check if reader thread is already set
if (this.reader == null) {
this.reader = Thread.currentThread();
}
// check if it is always the same reading thread
if (this.reader != Thread.currentThread()) {
throw new IOException(readingSameThread);
}
// generate page to return
TablePage page = null;
if (pageNumber < this.pageNumber && pageNumber >= firstPageNumber) {
// read contents from "disk"
System.arraycopy(this.diskBuffer.get(pageNumber - 1), 0, buffer, 0, buffer.length);
try {
page = AbstractExtensionFactory.getExtensionFactory().createTablePage(this.schema, buffer);
} catch (Exception e) {
throw new IOException("Error initializing page: " + e.getMessage());
}
} else {
throw new IOException("This page does not exist.");
}
// wait to test prefetching
if (this.prefetch) {
try {
Thread.sleep(200);
} catch (InterruptedException e) {
// do nothing
}
}
return page;
}
