org.sourcepit.docker.watcher.State.java Source code

Introduction

Here is the source code for org.sourcepit.docker.watcher.State.java

Source

/*
 * Copyright 2015 Bernd Vogt and others.
 * 
 * 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 org.sourcepit.docker.watcher;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonNull;
import com.google.gson.JsonObject;

public abstract class State {

    private static final Logger LOG = LoggerFactory.getLogger(State.class);

    private Map<String, JsonObject> state = new HashMap<>();

    public void applyLastKnownState(JsonArray containers) {
        final Map<String, JsonObject> newState = new HashMap<>();
        final Map<String, JsonObject> oldState = new HashMap<>(state);

        final List<JsonObject> events = new ArrayList<>();

        for (JsonElement jsonElement : containers) {
            final JsonObject container = (JsonObject) jsonElement;
            final String id = container.get("Id").getAsString();
            final JsonObject event = event(oldState.remove(id), container);
            if (event != null) {
                events.add(event);
            }
            newState.put(id, container);
        }

        for (JsonObject jsonObject : oldState.values()) {
            final JsonObject event = event(jsonObject, null);
            if (event != null) {
                events.add(event);
            }
        }

        state = newState;
        handle(events);
    }

    protected abstract void handle(final List<JsonObject> events);

    private JsonObject event(JsonObject oldContainer, JsonObject newContainer) {
        if (oldContainer == null) {
            if (newContainer != null) {
                return createEvent(null, null, getStatus(newContainer), newContainer);
            }
        }

        if (newContainer == null) {
            if (oldContainer != null) {
                return createEvent(getStatus(oldContainer), oldContainer, null, null);
            }
        }

        final String oldStatus = getStatus(oldContainer);
        final String newStatus = getStatus(newContainer);
        return createEvent(oldStatus, oldContainer, newStatus, newContainer);
    }

    private static JsonObject createEvent(final String oldStatus, JsonObject oldDetail, final String newStatus,
            JsonObject newDetail) {
        JsonObject event = new JsonObject();
        if (oldStatus == null) {
            event.add("OldState", JsonNull.INSTANCE);
        } else {
            event.addProperty("OldState", oldStatus);
        }
        if (newStatus == null) {
            event.add("NewState", JsonNull.INSTANCE);
        } else {
            event.addProperty("NewState", newStatus);
        }
        event.add("OldDetail", oldDetail == null ? JsonNull.INSTANCE : oldDetail);
        event.add("NewDetail", newDetail == null ? JsonNull.INSTANCE : newDetail);
        return event;
    }

    private String getStatus(JsonObject container) {
        final String currentStatus = container.get("Status").getAsString();
        if (currentStatus.startsWith("Exited ")) {
            return "STOPPED";
        } else if (currentStatus.startsWith("Up ")) {
            return "RUNNING";
        } else {
            throw new UnsupportedOperationException("Unknown container status: " + currentStatus);
        }
    }
}