ProtocolV2HookChain.java

/*
 * Copyright (C) 2019, Google LLC. and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
package org.eclipse.jgit.transport;

import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

/**
 * {@link org.eclipse.jgit.transport.ProtocolV2Hook} that delegates to a list of
 * other hooks.
 * <p>
 * Hooks are run in the order passed to the constructor. If running a method on
 * one hook throws an exception, execution of remaining hook methods is aborted.
 *
 * @since 5.5
 */
public class ProtocolV2HookChain implements ProtocolV2Hook {
    private final List<? extends ProtocolV2Hook> hooks;

    /**
     * Create a new hook chaining the given hooks together.
     *
     * @param hooks
     *            hooks to execute, in order.
     * @return a new hook chain of the given hooks.
     */
    public static ProtocolV2Hook newChain(
            List<? extends ProtocolV2Hook> hooks) {
        List<? extends ProtocolV2Hook> newHooks = hooks.stream()
                .filter(hook -> !hook.equals(ProtocolV2Hook.DEFAULT))
                .collect(Collectors.toList());

        if (newHooks.isEmpty()) {
            return ProtocolV2Hook.DEFAULT;
        } else if (newHooks.size() == 1) {
            return newHooks.get(0);
        } else {
            return new ProtocolV2HookChain(newHooks);
        }
    }

    @Override
    public void onCapabilities(CapabilitiesV2Request req)
            throws ServiceMayNotContinueException {
        for (ProtocolV2Hook hook : hooks) {
            hook.onCapabilities(req);
        }
    }

    @Override
    public void onLsRefs(LsRefsV2Request req)
            throws ServiceMayNotContinueException {
        for (ProtocolV2Hook hook : hooks) {
            hook.onLsRefs(req);
        }
    }

    @Override
    public void onFetch(FetchV2Request req)
            throws ServiceMayNotContinueException {
        for (ProtocolV2Hook hook : hooks) {
            hook.onFetch(req);
        }
    }

    private ProtocolV2HookChain(List<? extends ProtocolV2Hook> hooks) {
        this.hooks = Collections.unmodifiableList(hooks);
    }
}