com.google.gerrit.sshd.DispatchCommandProvider.java Source code

Introduction

Here is the source code for com.google.gerrit.sshd.DispatchCommandProvider.java

Source

// Copyright (C) 2009 The Android Open Source Project
//
// 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.google.gerrit.sshd;

import com.google.common.collect.Maps;
import com.google.gerrit.extensions.registration.RegistrationHandle;
import com.google.inject.Binding;
import com.google.inject.Inject;
import com.google.inject.Injector;
import com.google.inject.Provider;
import com.google.inject.TypeLiteral;

import org.apache.sshd.server.Command;

import java.lang.annotation.Annotation;
import java.util.List;
import java.util.concurrent.ConcurrentMap;

/**
 * Creates DispatchCommand using commands registered by {@link CommandModule}.
 */
public class DispatchCommandProvider implements Provider<DispatchCommand> {
    @Inject
    private Injector injector;

    @Inject
    private DispatchCommand.Factory factory;

    private final CommandName parent;
    private volatile ConcurrentMap<String, CommandProvider> map;

    public DispatchCommandProvider(final CommandName cn) {
        this.parent = cn;
    }

    @Override
    public DispatchCommand get() {
        return factory.create(getMap());
    }

    public RegistrationHandle register(final CommandName name, final Provider<Command> cmd) {
        final ConcurrentMap<String, CommandProvider> m = getMap();
        if (m.putIfAbsent(name.value(), new CommandProvider(cmd, null)) != null) {
            throw new IllegalArgumentException(name.value() + " exists");
        }
        return new RegistrationHandle() {
            @Override
            public void remove() {
                m.remove(name.value(), cmd);
            }
        };
    }

    public RegistrationHandle replace(final CommandName name, final Provider<Command> cmd) {
        final ConcurrentMap<String, CommandProvider> m = getMap();
        m.put(name.value(), new CommandProvider(cmd, null));
        return new RegistrationHandle() {
            @Override
            public void remove() {
                m.remove(name.value(), cmd);
            }
        };
    }

    ConcurrentMap<String, CommandProvider> getMap() {
        if (map == null) {
            synchronized (this) {
                if (map == null) {
                    map = createMap();
                }
            }
        }
        return map;
    }

    @SuppressWarnings("unchecked")
    private ConcurrentMap<String, CommandProvider> createMap() {
        ConcurrentMap<String, CommandProvider> m = Maps.newConcurrentMap();
        for (final Binding<?> b : allCommands()) {
            final Annotation annotation = b.getKey().getAnnotation();
            if (annotation instanceof CommandName) {
                final CommandName n = (CommandName) annotation;
                if (!Commands.CMD_ROOT.equals(n) && Commands.isChild(parent, n)) {
                    String descr = null;
                    if (annotation instanceof Commands.NestedCommandNameImpl) {
                        Commands.NestedCommandNameImpl impl = ((Commands.NestedCommandNameImpl) annotation);
                        descr = impl.descr();
                    }
                    m.put(n.value(), new CommandProvider((Provider<Command>) b.getProvider(), descr));
                }
            }
        }
        return m;
    }

    private static final TypeLiteral<Command> type = new TypeLiteral<Command>() {
    };

    private List<Binding<Command>> allCommands() {
        return injector.findBindingsByType(type);
    }
}