com.goodow.wind.server.rpc.DeltaHandler.java Source code

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Here is the source code for com.goodow.wind.server.rpc.DeltaHandler.java

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/*
 * Copyright 2012 Goodow.com
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package com.goodow.wind.server.rpc;

import com.goodow.wind.channel.rpc.Constants.Params;
import com.goodow.wind.server.model.Delta;
import com.goodow.wind.server.model.DeltaSerializer;
import com.goodow.wind.server.model.ObjectId;
import com.goodow.wind.server.model.SessionId;

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import com.google.inject.Inject;
import com.google.walkaround.slob.server.AccessDeniedException;
import com.google.walkaround.slob.server.LocalMutationProcessor;
import com.google.walkaround.slob.server.SlobFacilities;
import com.google.walkaround.slob.server.SlobNotFoundException;
import com.google.walkaround.slob.server.SlobStore;
import com.google.walkaround.slob.server.SlobStore.ConnectResult;
import com.google.walkaround.slob.server.SlobStore.HistoryResult;
import com.google.walkaround.util.server.servlet.AbstractHandler;
import com.google.walkaround.util.server.servlet.BadRequestException;

import java.io.IOException;
import java.util.List;
import java.util.logging.Logger;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Used by the client to notify the server of connection to an object at a specific revision, or to
 * refresh a channel.
 */
public class DeltaHandler extends AbstractHandler {

    @SuppressWarnings("unused")
    private static final Logger log = Logger.getLogger(DeltaHandler.class.getName());

    @Inject
    SlobFacilities slobFacilities;

    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        String keyString = requireParameter(req, Params.ID);
        JsonObject toRtn;
        try {
            if (!keyString.startsWith("[")) {
                Long version = Long.parseLong(requireParameter(req, Params.VERSION));
                String endVersionString = optionalParameter(req, Params.END_VERSION, null);
                Long endVersion = endVersionString == null ? null : Long.parseLong(endVersionString);
                toRtn = fetchHistory(new ObjectId(keyString), version, endVersion);
            } else {
                JsonElement keys = new JsonParser().parse(keyString);
                assert keys.isJsonArray();
                String sid = requireParameter(req, Params.SESSION_ID);
                toRtn = fetchHistories(new SessionId(sid), keys.getAsJsonArray());
            }
        } catch (SlobNotFoundException e) {
            throw new BadRequestException("Object not found or access denied", e);
        } catch (AccessDeniedException e) {
            throw new BadRequestException("Object not found or access denied", e);
        } catch (NumberFormatException nfe) {
            throw new BadRequestException("Parse error", nfe);
        }

        resp.setContentType("application/json");
        Util.writeJsonResult(resp.getWriter(), toRtn.toString());
    }

    private JsonObject fetchHistories(SessionId sid, JsonArray keys)
            throws IOException, SlobNotFoundException, AccessDeniedException {
        SlobStore store = slobFacilities.getSlobStore();
        JsonObject toRtn = new JsonObject();
        JsonArray msgs = new JsonArray();
        String token = null;
        for (JsonElement e : keys) {
            JsonObject obj = e.getAsJsonObject();
            ObjectId key = new ObjectId(obj.get(Params.ID).getAsString());
            long version = obj.get(Params.VERSION).getAsLong();
            Long endVersion = obj.has(Params.END_VERSION) ? obj.get(Params.END_VERSION).getAsLong() : null;
            ConnectResult r = store.reconnect(key, sid);
            JsonObject msg;
            if (r.getChannelToken() != null) {
                assert token == null || token.equals(r.getChannelToken());
                token = r.getChannelToken();
            }
            HistoryResult history = store.loadHistory(key, version, endVersion);
            msg = LocalMutationProcessor.jsonBroadcastData(key.toString(),
                    serializeHistory(version, history.getData()));
            msg.addProperty(Params.VERSION, r.getVersion());
            msgs.add(msg);
        }
        if (token != null) {
            toRtn.addProperty(Params.TOKEN, token);
        }
        toRtn.add(Params.DELTAS, msgs);
        return toRtn;
    }

    private JsonObject fetchHistory(ObjectId key, long version, Long endVersion)
            throws IOException, SlobNotFoundException, AccessDeniedException {
        SlobStore store = slobFacilities.getSlobStore();
        JsonObject result = new JsonObject();
        HistoryResult history = store.loadHistory(key, version, endVersion);
        result.add(Params.DELTAS, serializeHistory(version, history.getData()));
        result.addProperty(Params.HAS_MORE, history.hasMore());
        return result;
    }

    private JsonArray serializeHistory(long startVersion, List<Delta<String>> entries) {
        JsonArray history = new JsonArray();
        int index = 0;
        for (Delta<String> data : entries) {
            history.add(DeltaSerializer.dataToClientJson(data, startVersion + index + 1));
            index++;
        }
        return history;
    }
}