org.eclipse.jgit/src/org/eclipse/jgit/internal/ketch/Proposal.java - jgit - Git at Google

 /*
  * Copyright (C) 2016, Google Inc. 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.internal.ketch;

 import static org.eclipse.jgit.internal.ketch.Proposal.State.ABORTED;
 import static org.eclipse.jgit.internal.ketch.Proposal.State.EXECUTED;
 import static org.eclipse.jgit.internal.ketch.Proposal.State.NEW;
 import static org.eclipse.jgit.transport.ReceiveCommand.Result.NOT_ATTEMPTED;
 import static org.eclipse.jgit.transport.ReceiveCommand.Result.OK;

 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReference;

 import org.eclipse.jgit.annotations.Nullable;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.internal.storage.reftree.Command;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.PersonIdent;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.transport.PushCertificate;
 import org.eclipse.jgit.transport.ReceiveCommand;
 import org.eclipse.jgit.util.time.ProposedTimestamp;

 /**
  * A proposal to be applied in a Ketch system.
  * <p>
  * Pushing to a Ketch leader results in the leader making a proposal. The
  * proposal includes the list of reference updates. The leader attempts to send
  * the proposal to a quorum of replicas by pushing the proposal to a "staging"
  * area under the {@code refs/txn/stage/} namespace. If the proposal succeeds
  * then the changes are durable and the leader can commit the proposal.
  * <p>
  * Proposals are executed by
  * {@link org.eclipse.jgit.internal.ketch.KetchLeader#queueProposal(Proposal)},
  * which runs them asynchronously in the background. Proposals are thread-safe
  * futures allowing callers to {@link #await()} for results or be notified by
  * callback using {@link #addListener(Runnable)}.
  */
 public class Proposal {
 	/** Current state of the proposal. */
 	public enum State {
 		/** Proposal has not yet been given to a {@link KetchLeader}. */
 		NEW(false),

 		/**
 		 * Proposal was validated and has entered the queue, but a round
 		 * containing this proposal has not started yet.
 		 */
 		QUEUED(false),

 		/** Round containing the proposal has begun and is in progress. */
 		RUNNING(false),

 		/**
 		 * Proposal was executed through a round. Individual results from
 		 * {@link Proposal#getCommands()}, {@link Command#getResult()} explain
 		 * the success or failure outcome.
 		 */
 		EXECUTED(true),

 		/** Proposal was aborted and did not reach consensus. */
 		ABORTED(true);

 		private final boolean done;

 		private State(boolean done) {
 			this.done = done;
 		}

 		/** @return true if this is a terminal state. */
 		public boolean isDone() {
 			return done;
 		}
 	}

 	private final List<Command> commands;
 	private PersonIdent author;
 	private String message;
 	private PushCertificate pushCert;

 	private List<ProposedTimestamp> timestamps;
 	private final List<Runnable> listeners = new CopyOnWriteArrayList<>();
 	private final AtomicReference<State> state = new AtomicReference<>(NEW);

 	/**
 	 * Create a proposal from a list of Ketch commands.
 	 *
 	 * @param cmds
 	 *            prepared list of commands.
 	 */
 	public Proposal(List<Command> cmds) {
 		commands = Collections.unmodifiableList(new ArrayList<>(cmds));
 	}

 	/**
 	 * Create a proposal from a collection of received commands.
 	 *
 	 * @param rw
 	 *            walker to assist in preparing commands.
 	 * @param cmds
 	 *            list of pending commands.
 	 * @throws org.eclipse.jgit.errors.MissingObjectException
 	 *             newId of a command is not found locally.
 	 * @throws java.io.IOException
 	 *             local objects cannot be accessed.
 	 */
 	public Proposal(RevWalk rw, Collection<ReceiveCommand> cmds)
 			throws MissingObjectException, IOException {
 		commands = asCommandList(rw, cmds);
 	}

 	private static List<Command> asCommandList(RevWalk rw,
 			Collection<ReceiveCommand> cmds)
 					throws MissingObjectException, IOException {
 		List<Command> commands = new ArrayList<>(cmds.size());
 		for (ReceiveCommand cmd : cmds) {
 			commands.add(new Command(rw, cmd));
 		}
 		return Collections.unmodifiableList(commands);
 	}

 	/**
 	 * Get commands from this proposal.
 	 *
 	 * @return commands from this proposal.
 	 */
 	public Collection<Command> getCommands() {
 		return commands;
 	}

 	/**
 	 * Get optional author of the proposal.
 	 *
 	 * @return optional author of the proposal.
 	 */
 	@Nullable
 	public PersonIdent getAuthor() {
 		return author;
 	}

 	/**
 	 * Set the author for the proposal.
 	 *
 	 * @param who
 	 *            optional identity of the author of the proposal.
 	 * @return {@code this}
 	 */
 	public Proposal setAuthor(@Nullable PersonIdent who) {
 		author = who;
 		return this;
 	}

 	/**
 	 * Get optional message for the commit log of the RefTree.
 	 *
 	 * @return optional message for the commit log of the RefTree.
 	 */
 	@Nullable
 	public String getMessage() {
 		return message;
 	}

 	/**
 	 * Set the message to appear in the commit log of the RefTree.
 	 *
 	 * @param msg
 	 *            message text for the commit.
 	 * @return {@code this}
 	 */
 	public Proposal setMessage(@Nullable String msg) {
 		message = msg != null && !msg.isEmpty() ? msg : null;
 		return this;
 	}

 	/**
 	 * Get optional certificate signing the references.
 	 *
 	 * @return optional certificate signing the references.
 	 */
 	@Nullable
 	public PushCertificate getPushCertificate() {
 		return pushCert;
 	}

 	/**
 	 * Set the push certificate signing the references.
 	 *
 	 * @param cert
 	 *            certificate, may be null.
 	 * @return {@code this}
 	 */
 	public Proposal setPushCertificate(@Nullable PushCertificate cert) {
 		pushCert = cert;
 		return this;
 	}

 	/**
 	 * Get timestamps that Ketch must block for.
 	 *
 	 * @return timestamps that Ketch must block for. These may have been used as
 	 *         commit times inside the objects involved in the proposal.
 	 */
 	public List<ProposedTimestamp> getProposedTimestamps() {
 		if (timestamps != null) {
 			return timestamps;
 		}
 		return Collections.emptyList();
 	}

 	/**
 	 * Request the proposal to wait for the affected timestamps to resolve.
 	 *
 	 * @param ts
 	 *            a {@link org.eclipse.jgit.util.time.ProposedTimestamp} object.
 	 * @return {@code this}.
 	 */
 	public Proposal addProposedTimestamp(ProposedTimestamp ts) {
 		if (timestamps == null) {
 			timestamps = new ArrayList<>(4);
 		}
 		timestamps.add(ts);
 		return this;
 	}

 	/**
 	 * Add a callback to be invoked when the proposal is done.
 	 * <p>
 	 * A proposal is done when it has entered either
 	 * {@link org.eclipse.jgit.internal.ketch.Proposal.State#EXECUTED} or
 	 * {@link org.eclipse.jgit.internal.ketch.Proposal.State#ABORTED} state. If
 	 * the proposal is already done {@code callback.run()} is immediately
 	 * invoked on the caller's thread.
 	 *
 	 * @param callback
 	 *            method to run after the proposal is done. The callback may be
 	 *            run on a Ketch system thread and should be completed quickly.
 	 */
 	public void addListener(Runnable callback) {
 		boolean runNow = false;
 		synchronized (state) {
 			if (state.get().isDone()) {
 				runNow = true;
 			} else {
 				listeners.add(callback);
 			}
 		}
 		if (runNow) {
 			callback.run();
 		}
 	}

 	/** Set command result as OK. */
 	void success() {
 		for (Command c : commands) {
 			if (c.getResult() == NOT_ATTEMPTED) {
 				c.setResult(OK);
 			}
 		}
 		notifyState(EXECUTED);
 	}

 	/** Mark commands as "transaction aborted". */
 	void abort() {
 		Command.abort(commands, null);
 		notifyState(ABORTED);
 	}

 	/**
 	 * Read the current state of the proposal.
 	 *
 	 * @return read the current state of the proposal.
 	 */
 	public State getState() {
 		return state.get();
 	}

 	/**
 	 * Whether the proposal was attempted
 	 *
 	 * @return {@code true} if the proposal was attempted. A true value does not
 	 *         mean consensus was reached, only that the proposal was considered
 	 *         and will not be making any more progress beyond its current
 	 *         state.
 	 */
 	public boolean isDone() {
 		return state.get().isDone();
 	}

 	/**
 	 * Wait for the proposal to be attempted and {@link #isDone()} to be true.
 	 *
 	 * @throws java.lang.InterruptedException
 	 *             caller was interrupted before proposal executed.
 	 */
 	public void await() throws InterruptedException {
 		synchronized (state) {
 			while (!state.get().isDone()) {
 				state.wait();
 			}
 		}
 	}

 	/**
 	 * Wait for the proposal to be attempted and {@link #isDone()} to be true.
 	 *
 	 * @param wait
 	 *            how long to wait.
 	 * @param unit
 	 *            unit describing the wait time.
 	 * @return true if the proposal is done; false if the method timed out.
 	 * @throws java.lang.InterruptedException
 	 *             caller was interrupted before proposal executed.
 	 */
 	public boolean await(long wait, TimeUnit unit) throws InterruptedException {
 		synchronized (state) {
 			if (state.get().isDone()) {
 				return true;
 			}
 			state.wait(unit.toMillis(wait));
 			return state.get().isDone();
 		}
 	}

 	/**
 	 * Wait for the proposal to exit a state.
 	 *
 	 * @param notIn
 	 *            state the proposal should not be in to return.
 	 * @param wait
 	 *            how long to wait.
 	 * @param unit
 	 *            unit describing the wait time.
 	 * @return true if the proposal exited the state; false on time out.
 	 * @throws java.lang.InterruptedException
 	 *             caller was interrupted before proposal executed.
 	 */
 	public boolean awaitStateChange(State notIn, long wait, TimeUnit unit)
 			throws InterruptedException {
 		synchronized (state) {
 			if (state.get() != notIn) {
 				return true;
 			}
 			state.wait(unit.toMillis(wait));
 			return state.get() != notIn;
 		}
 	}

 	void notifyState(State s) {
 		synchronized (state) {
 			state.set(s);
 			state.notifyAll();
 		}
 		if (s.isDone()) {
 			for (Runnable callback : listeners) {
 				callback.run();
 			}
 			listeners.clear();
 		}
 	}

 	/** {@inheritDoc} */
 	@Override
 	public String toString() {
 		StringBuilder s = new StringBuilder();
 		s.append("Ketch Proposal {\n"); //$NON-NLS-1$
 		s.append("  ").append(state.get()).append('\n'); //$NON-NLS-1$
 		if (author != null) {
 			s.append("  author ").append(author).append('\n'); //$NON-NLS-1$
 		}
 		if (message != null) {
 			s.append("  message ").append(message).append('\n'); //$NON-NLS-1$
 		}
 		for (Command c : commands) {
 			s.append("  "); //$NON-NLS-1$
 			format(s, c.getOldRef(), "CREATE"); //$NON-NLS-1$
 			s.append(' ');
 			format(s, c.getNewRef(), "DELETE"); //$NON-NLS-1$
 			s.append(' ').append(c.getRefName());
 			if (c.getResult() != ReceiveCommand.Result.NOT_ATTEMPTED) {
 				s.append(' ').append(c.getResult()); // $NON-NLS-1$
 			}
 			s.append('\n');
 		}
 		s.append('}');
 		return s.toString();
 	}

 	private static void format(StringBuilder s, @Nullable Ref r, String n) {
 		if (r == null) {
 			s.append(n);
 		} else if (r.isSymbolic()) {
 			s.append(r.getTarget().getName());
 		} else {
 			ObjectId id = r.getObjectId();
 			if (id != null) {
 				s.append(id.abbreviate(8).name());
 			}
 		}
 	}
 }
	/*
	* Copyright (C) 2016, Google Inc. 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.internal.ketch;

	import static org.eclipse.jgit.internal.ketch.Proposal.State.ABORTED;
	import static org.eclipse.jgit.internal.ketch.Proposal.State.EXECUTED;
	import static org.eclipse.jgit.internal.ketch.Proposal.State.NEW;
	import static org.eclipse.jgit.transport.ReceiveCommand.Result.NOT_ATTEMPTED;
	import static org.eclipse.jgit.transport.ReceiveCommand.Result.OK;

	import java.io.IOException;
	import java.util.ArrayList;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.List;
	import java.util.concurrent.CopyOnWriteArrayList;
	import java.util.concurrent.TimeUnit;
	import java.util.concurrent.atomic.AtomicReference;

	import org.eclipse.jgit.annotations.Nullable;
	import org.eclipse.jgit.errors.MissingObjectException;
	import org.eclipse.jgit.internal.storage.reftree.Command;
	import org.eclipse.jgit.lib.ObjectId;
	import org.eclipse.jgit.lib.PersonIdent;
	import org.eclipse.jgit.lib.Ref;
	import org.eclipse.jgit.revwalk.RevWalk;
	import org.eclipse.jgit.transport.PushCertificate;
	import org.eclipse.jgit.transport.ReceiveCommand;
	import org.eclipse.jgit.util.time.ProposedTimestamp;

	/**
	* A proposal to be applied in a Ketch system.
	* <p>
	* Pushing to a Ketch leader results in the leader making a proposal. The
	* proposal includes the list of reference updates. The leader attempts to send
	* the proposal to a quorum of replicas by pushing the proposal to a "staging"
	* area under the {@code refs/txn/stage/} namespace. If the proposal succeeds
	* then the changes are durable and the leader can commit the proposal.
	* <p>
	* Proposals are executed by
	* {@link org.eclipse.jgit.internal.ketch.KetchLeader#queueProposal(Proposal)},
	* which runs them asynchronously in the background. Proposals are thread-safe
	* futures allowing callers to {@link #await()} for results or be notified by
	* callback using {@link #addListener(Runnable)}.
	*/
	public class Proposal {
	/** Current state of the proposal. */
	public enum State {
	/** Proposal has not yet been given to a {@link KetchLeader}. */
	NEW(false),

	/**
	* Proposal was validated and has entered the queue, but a round
	* containing this proposal has not started yet.
	*/
	QUEUED(false),

	/** Round containing the proposal has begun and is in progress. */
	RUNNING(false),

	/**
	* Proposal was executed through a round. Individual results from
	* {@link Proposal#getCommands()}, {@link Command#getResult()} explain
	* the success or failure outcome.
	*/
	EXECUTED(true),

	/** Proposal was aborted and did not reach consensus. */
	ABORTED(true);

	private final boolean done;

	private State(boolean done) {
	this.done = done;
	}

	/** @return true if this is a terminal state. */
	public boolean isDone() {
	return done;
	}
	}

	private final List<Command> commands;
	private PersonIdent author;
	private String message;
	private PushCertificate pushCert;

	private List<ProposedTimestamp> timestamps;
	private final List<Runnable> listeners = new CopyOnWriteArrayList<>();
	private final AtomicReference<State> state = new AtomicReference<>(NEW);

	/**
	* Create a proposal from a list of Ketch commands.
	*
	* @param cmds
	* prepared list of commands.
	*/
	public Proposal(List<Command> cmds) {
	commands = Collections.unmodifiableList(new ArrayList<>(cmds));
	}

	/**
	* Create a proposal from a collection of received commands.
	*
	* @param rw
	* walker to assist in preparing commands.
	* @param cmds
	* list of pending commands.
	* @throws org.eclipse.jgit.errors.MissingObjectException
	* newId of a command is not found locally.
	* @throws java.io.IOException
	* local objects cannot be accessed.
	*/
	public Proposal(RevWalk rw, Collection<ReceiveCommand> cmds)
	throws MissingObjectException, IOException {
	commands = asCommandList(rw, cmds);
	}

	private static List<Command> asCommandList(RevWalk rw,
	Collection<ReceiveCommand> cmds)
	throws MissingObjectException, IOException {
	List<Command> commands = new ArrayList<>(cmds.size());
	for (ReceiveCommand cmd : cmds) {
	commands.add(new Command(rw, cmd));
	}
	return Collections.unmodifiableList(commands);
	}

	/**
	* Get commands from this proposal.
	*
	* @return commands from this proposal.
	*/
	public Collection<Command> getCommands() {
	return commands;
	}

	/**
	* Get optional author of the proposal.
	*
	* @return optional author of the proposal.
	*/
	@Nullable
	public PersonIdent getAuthor() {
	return author;
	}

	/**
	* Set the author for the proposal.
	*
	* @param who
	* optional identity of the author of the proposal.
	* @return {@code this}
	*/
	public Proposal setAuthor(@Nullable PersonIdent who) {
	author = who;
	return this;
	}

	/**
	* Get optional message for the commit log of the RefTree.
	*
	* @return optional message for the commit log of the RefTree.
	*/
	@Nullable
	public String getMessage() {
	return message;
	}

	/**
	* Set the message to appear in the commit log of the RefTree.
	*
	* @param msg
	* message text for the commit.
	* @return {@code this}
	*/
	public Proposal setMessage(@Nullable String msg) {
	message = msg != null && !msg.isEmpty() ? msg : null;
	return this;
	}

	/**
	* Get optional certificate signing the references.
	*
	* @return optional certificate signing the references.
	*/
	@Nullable
	public PushCertificate getPushCertificate() {
	return pushCert;
	}

	/**
	* Set the push certificate signing the references.
	*
	* @param cert
	* certificate, may be null.
	* @return {@code this}
	*/
	public Proposal setPushCertificate(@Nullable PushCertificate cert) {
	pushCert = cert;
	return this;
	}

	/**
	* Get timestamps that Ketch must block for.
	*
	* @return timestamps that Ketch must block for. These may have been used as
	* commit times inside the objects involved in the proposal.
	*/
	public List<ProposedTimestamp> getProposedTimestamps() {
	if (timestamps != null) {
	return timestamps;
	}
	return Collections.emptyList();
	}

	/**
	* Request the proposal to wait for the affected timestamps to resolve.
	*
	* @param ts
	* a {@link org.eclipse.jgit.util.time.ProposedTimestamp} object.
	* @return {@code this}.
	*/
	public Proposal addProposedTimestamp(ProposedTimestamp ts) {
	if (timestamps == null) {
	timestamps = new ArrayList<>(4);
	}
	timestamps.add(ts);
	return this;
	}

	/**
	* Add a callback to be invoked when the proposal is done.
	* <p>
	* A proposal is done when it has entered either
	* {@link org.eclipse.jgit.internal.ketch.Proposal.State#EXECUTED} or
	* {@link org.eclipse.jgit.internal.ketch.Proposal.State#ABORTED} state. If
	* the proposal is already done {@code callback.run()} is immediately
	* invoked on the caller's thread.
	*
	* @param callback
	* method to run after the proposal is done. The callback may be
	* run on a Ketch system thread and should be completed quickly.
	*/
	public void addListener(Runnable callback) {
	boolean runNow = false;
	synchronized (state) {
	if (state.get().isDone()) {
	runNow = true;
	} else {
	listeners.add(callback);
	}
	}
	if (runNow) {
	callback.run();
	}
	}

	/** Set command result as OK. */
	void success() {
	for (Command c : commands) {
	if (c.getResult() == NOT_ATTEMPTED) {
	c.setResult(OK);
	}
	}
	notifyState(EXECUTED);
	}

	/** Mark commands as "transaction aborted". */
	void abort() {
	Command.abort(commands, null);
	notifyState(ABORTED);
	}

	/**
	* Read the current state of the proposal.
	*
	* @return read the current state of the proposal.
	*/
	public State getState() {
	return state.get();
	}

	/**
	* Whether the proposal was attempted
	*
	* @return {@code true} if the proposal was attempted. A true value does not
	* mean consensus was reached, only that the proposal was considered
	* and will not be making any more progress beyond its current
	* state.
	*/
	public boolean isDone() {
	return state.get().isDone();
	}

	/**
	* Wait for the proposal to be attempted and {@link #isDone()} to be true.
	*
	* @throws java.lang.InterruptedException
	* caller was interrupted before proposal executed.
	*/
	public void await() throws InterruptedException {
	synchronized (state) {
	while (!state.get().isDone()) {
	state.wait();
	}
	}
	}

	/**
	* Wait for the proposal to be attempted and {@link #isDone()} to be true.
	*
	* @param wait
	* how long to wait.
	* @param unit
	* unit describing the wait time.
	* @return true if the proposal is done; false if the method timed out.
	* @throws java.lang.InterruptedException
	* caller was interrupted before proposal executed.
	*/
	public boolean await(long wait, TimeUnit unit) throws InterruptedException {
	synchronized (state) {
	if (state.get().isDone()) {
	return true;
	}
	state.wait(unit.toMillis(wait));
	return state.get().isDone();
	}
	}

	/**
	* Wait for the proposal to exit a state.
	*
	* @param notIn
	* state the proposal should not be in to return.
	* @param wait
	* how long to wait.
	* @param unit
	* unit describing the wait time.
	* @return true if the proposal exited the state; false on time out.
	* @throws java.lang.InterruptedException
	* caller was interrupted before proposal executed.
	*/
	public boolean awaitStateChange(State notIn, long wait, TimeUnit unit)
	throws InterruptedException {
	synchronized (state) {
	if (state.get() != notIn) {
	return true;
	}
	state.wait(unit.toMillis(wait));
	return state.get() != notIn;
	}
	}

	void notifyState(State s) {
	synchronized (state) {
	state.set(s);
	state.notifyAll();
	}
	if (s.isDone()) {
	for (Runnable callback : listeners) {
	callback.run();
	}
	listeners.clear();
	}
	}

	/** {@inheritDoc} */
	@Override
	public String toString() {
	StringBuilder s = new StringBuilder();
	s.append("Ketch Proposal {\n"); //$NON-NLS-1$
	s.append(" ").append(state.get()).append('\n'); //$NON-NLS-1$
	if (author != null) {
	s.append(" author ").append(author).append('\n'); //$NON-NLS-1$
	}
	if (message != null) {
	s.append(" message ").append(message).append('\n'); //$NON-NLS-1$
	}
	for (Command c : commands) {
	s.append(" "); //$NON-NLS-1$
	format(s, c.getOldRef(), "CREATE"); //$NON-NLS-1$
	s.append(' ');
	format(s, c.getNewRef(), "DELETE"); //$NON-NLS-1$
	s.append(' ').append(c.getRefName());
	if (c.getResult() != ReceiveCommand.Result.NOT_ATTEMPTED) {
	s.append(' ').append(c.getResult()); // $NON-NLS-1$
	}
	s.append('\n');
	}
	s.append('}');
	return s.toString();
	}

	private static void format(StringBuilder s, @Nullable Ref r, String n) {
	if (r == null) {
	s.append(n);
	} else if (r.isSymbolic()) {
	s.append(r.getTarget().getName());
	} else {
	ObjectId id = r.getObjectId();
	if (id != null) {
	s.append(id.abbreviate(8).name());
	}
	}
	}
	}