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Copyright 2010, Google Inc.
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*/
package com.google.refine.history;
import java.io.Writer;
import java.util.Date;
import java.util.Properties;
import org.json.JSONException;
import org.json.JSONObject;
import org.json.JSONWriter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.refine.Jsonizable;
import com.google.refine.ProjectManager;
import com.google.refine.model.AbstractOperation;
import com.google.refine.model.Project;
import com.google.refine.operations.OperationRegistry;
import com.google.refine.util.ParsingUtilities;
/**
* This is the metadata of a Change. It's small, so we can load it in order to
* obtain information about a change without actually loading the change.
*/
public class HistoryEntry implements Jsonizable {
final static Logger logger = LoggerFactory.getLogger("HistoryEntry");
final public long id;
final public long projectID;
final public String description;
final public Date time;
// the manager (deals with IO systems or databases etc.)
final public HistoryEntryManager _manager;
// the abstract operation, if any, that results in the change
final public AbstractOperation operation;
// the actual change, loaded on demand
private transient Change _change;
private final static String OPERATION = "operation";
public void setChange(Change _change) {
this._change = _change;
}
public Change getChange() {
return _change;
}
static public long allocateID() {
return Math.round(Math.random() * 1000000) + System.currentTimeMillis();
}
public HistoryEntry(long id, Project project, String description, AbstractOperation operation, Change change) {
this(id,project.id,description,operation,new Date());
setChange(change);
}
protected HistoryEntry(long id, long projectID, String description, AbstractOperation operation, Date time) {
this.id = id;
this.projectID = projectID;
this.description = description;
this.operation = operation;
this.time = time;
this._manager = ProjectManager.singleton.getHistoryEntryManager();
if (this._manager == null) {
logger.error("Failed to get history entry manager from project manager: "
+ ProjectManager.singleton );
}
}
@Override
public void write(JSONWriter writer, Properties options)
throws JSONException {
writer.object();
writer.key("id"); writer.value(id);
writer.key("description"); writer.value(description);
writer.key("time"); writer.value(ParsingUtilities.dateToString(time));
if ("save".equals(options.getProperty("mode")) && operation != null) {
writer.key(OPERATION); operation.write(writer, options);
}
writer.endObject();
}
public void save(Writer writer, Properties options){
_manager.save(this, writer, options);
}
/**
* Apply a change to a project. In most cases you should already hold the Project lock
* before calling this method to prevent deadlocks.
*
* @param project the project the change should be applied to
*/
public void apply(Project project) {
if (getChange() == null) {
ProjectManager.singleton.getHistoryEntryManager().loadChange(this);
}
synchronized (project) {
getChange().apply(project);
// When a change is applied, it can hang on to old data (in order to be able
// to revert later). Hence, we need to save the change out.
try {
_manager.saveChange(this);
} catch (Exception e) {
e.printStackTrace();
getChange().revert(project);
throw new RuntimeException("Failed to apply change", e);
}
}
}
public void revert(Project project) {
if (getChange() == null) {
_manager.loadChange(this);
}
getChange().revert(project);
}
static public HistoryEntry load(Project project, String s) throws Exception {
JSONObject obj = ParsingUtilities.evaluateJsonStringToObject(s);
AbstractOperation operation = null;
if (obj.has(OPERATION) && !obj.isNull(OPERATION)) {
operation = OperationRegistry.reconstruct(project, obj.getJSONObject(OPERATION));
}
return new HistoryEntry(
obj.getLong("id"),
project.id,
obj.getString("description"),
operation,
ParsingUtilities.stringToDate(obj.getString("time"))
);
}
public void delete(){
_manager.delete(this);
}
}