예제 #1
0
 /*
  * (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;
 }
예제 #2
0
  /*
   * (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;
  }