Android Open Source - Jello Simple Schema Manager

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License

The source code is released under:
Apache License
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Java Source Code

package com.atteo.jello.schema;
/*from  w  w  w.  j  a v a  2s . c om*/
import java.util.ArrayList;

import com.atteo.jello.space.SpaceManagerPolicy;
import com.atteo.jello.store.ListPage;
import com.atteo.jello.store.PagedFile;
import com.google.inject.Inject;
import com.google.inject.assistedinject.Assisted;

public class SimpleSchemaManager implements SchemaManager {
  private final ArrayList<Schema> schemas;
  private final ArrayList<Integer> pageIds;
  private final PagedFile pagedFile;
  private final ListPage listPage;
  private final SpaceManagerPolicy spaceManagerPolicy;

  @Inject
  public SimpleSchemaManager(final SpaceManagerPolicy spaceManagerPolicy,
      final ListPage listPage, final PagedFile pagedFile,
      @Assisted final int klassSchemaPageId) {
    this.listPage = listPage;
    this.pagedFile = pagedFile;
    this.spaceManagerPolicy = spaceManagerPolicy;

    pageIds = new ArrayList<Integer>();
    pageIds.add(klassSchemaPageId);

    schemas = new ArrayList<Schema>();
  }

  public int addSchema(final Schema schema) {
    final int l = schemas.size();
    for (int i = 0; i < l; i++)
      if (schema.equals(schemas.get(i)))
        return schemas.get(i).version;

    schema.version = schemas.size();
    schemas.add(schema);
    return schemas.size() - 1;
  }

  public void commit() {
    int schemasOnPage = 0;
    int currentPage = 0;
    final int l = schemas.size();

    int free = listPage.getCapacity() - 4;
    listPage.position(4);

    for (int i = 0; i < l; i++) {
      final Schema schema = schemas.get(i);
      final int fieldsLength = schema.fields.length;
      int required = 4;
      final String names[] = schema.names;
      final int fields[] = schema.fields;

      for (int j = 0; j < fieldsLength; j++)
        required += names[j].length() + 8;

      if (free < required) {
        if (currentPage + 1 >= pageIds.size())
          pageIds.add(spaceManagerPolicy.acquirePage());
        listPage.setNext(pageIds.get(currentPage + 1));
        listPage.setId(pageIds.get(currentPage));
        listPage.reset();
        listPage.putInt(schemasOnPage);
        pagedFile.writePage(listPage);
        currentPage++;
        free = listPage.getCapacity();
        schemasOnPage = 0;
        listPage.position(4);

      }

      free -= required;
      schemasOnPage++;
      listPage.putInt(fieldsLength);
      for (int j = 0; j < fieldsLength; j++) {
        listPage.putInt(names[j].length());
        listPage.putString(names[j]);
        listPage.putInt(fields[j]);
      }

    }

    listPage.setNext(ListPage.NO_MORE_PAGES);
    listPage.setId(pageIds.get(currentPage));
    listPage.reset();
    listPage.putInt(schemasOnPage);
    pagedFile.writePage(listPage);

    for (int i = currentPage + 1; i < pageIds.size(); i++) {
      spaceManagerPolicy.releasePage(pageIds.get(i));
      pageIds.remove(i);
    }
  }

  public void create() {
    listPage.setNext(ListPage.NO_MORE_PAGES);
    listPage.setId(pageIds.get(0));
    listPage.reset();
    listPage.putInt(0);
    pagedFile.writePage(listPage);
  }

  public Schema getSchema(final int version) {
    if (version < schemas.size())
      return schemas.get(version);
    else
      return null;
  }

  public boolean load() {
    int next;
    listPage.setId(pageIds.get(0));
    pagedFile.readPage(listPage);
    next = listPage.getNext();

    listPage.reset();
    readSchemasFromPage(listPage);

    while (next != ListPage.NO_MORE_PAGES) {
      pageIds.add(next);
      listPage.setId(next);
      pagedFile.readPage(listPage);
      next = listPage.getNext();
      listPage.reset();
      readSchemasFromPage(listPage);
    }

    return false;

  }

  public void removeSchema(final int version) {
    final int l = schemas.size();
    for (int i = 0; i < l; i++)
      if (version == schemas.get(i).version)
        schemas.remove(i);
  }

  private void readSchemasFromPage(final ListPage page) {
    final int schemasOnPage = page.getInt();
    int l;
    int nameLen;
    for (int i = 0; i < schemasOnPage; i++) {
      final Schema schema = new Schema();
      l = page.getInt();
      schema.fields = new int[l];
      schema.names = new String[l];

      for (int j = 0; j < l; j++) {
        nameLen = page.getInt();
        schema.names[j] = page.getString(nameLen);
        schema.fields[j] = page.getInt();
      }
      schemas.add(schema);
    }
  }

}
Java Source Code List
