java/com/google/gerrit/server/query/change/OutputStreamQuery.java - gerrit - Git at Google

 // Copyright (C) 2014 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.server.query.change;

 import static com.google.common.base.Preconditions.checkState;
 import static java.nio.charset.StandardCharsets.UTF_8;

 import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.data.LabelTypes;
 import com.google.gerrit.index.query.QueryParseException;
 import com.google.gerrit.index.query.QueryResult;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.DynamicOptions;
 import com.google.gerrit.server.config.TrackingFooters;
 import com.google.gerrit.server.data.ChangeAttribute;
 import com.google.gerrit.server.data.PatchSetAttribute;
 import com.google.gerrit.server.data.QueryStatsAttribute;
 import com.google.gerrit.server.events.EventFactory;
 import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.project.SubmitRuleEvaluator;
 import com.google.gerrit.server.project.SubmitRuleOptions;
 import com.google.gerrit.server.util.time.TimeUtil;
 import com.google.gson.Gson;
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
 import java.io.BufferedWriter;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
 import java.lang.reflect.Field;
 import java.time.Instant;
 import java.time.ZoneId;
 import java.time.format.DateTimeFormatter;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.util.io.DisabledOutputStream;

 /**
  * Change query implementation that outputs to a stream in the style of an SSH command.
  *
  * <p>Instances are one-time-use. Other singleton classes should inject a Provider rather than
  * holding on to a single instance.
  */
 public class OutputStreamQuery {
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();

   private static final DateTimeFormatter dtf =
       DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss zzz")
           .withLocale(Locale.US)
           .withZone(ZoneId.systemDefault());

   public enum OutputFormat {
     TEXT,
     JSON
   }

   public static final Gson GSON = new Gson();

   private final GitRepositoryManager repoManager;
   private final ChangeQueryBuilder queryBuilder;
   private final ChangeQueryProcessor queryProcessor;
   private final EventFactory eventFactory;
   private final TrackingFooters trackingFooters;
   private final SubmitRuleEvaluator.Factory submitRuleEvaluatorFactory;

   private OutputFormat outputFormat = OutputFormat.TEXT;
   private boolean includePatchSets;
   private boolean includeCurrentPatchSet;
   private boolean includeApprovals;
   private boolean includeComments;
   private boolean includeFiles;
   private boolean includeCommitMessage;
   private boolean includeDependencies;
   private boolean includeSubmitRecords;
   private boolean includeAllReviewers;

   private OutputStream outputStream = DisabledOutputStream.INSTANCE;
   private PrintWriter out;

   @Inject
   OutputStreamQuery(
       GitRepositoryManager repoManager,
       ChangeQueryBuilder queryBuilder,
       ChangeQueryProcessor queryProcessor,
       EventFactory eventFactory,
       TrackingFooters trackingFooters,
       SubmitRuleEvaluator.Factory submitRuleEvaluatorFactory) {
     this.repoManager = repoManager;
     this.queryBuilder = queryBuilder;
     this.queryProcessor = queryProcessor;
     this.eventFactory = eventFactory;
     this.trackingFooters = trackingFooters;
     this.submitRuleEvaluatorFactory = submitRuleEvaluatorFactory;
   }

   void setLimit(int n) {
     queryProcessor.setUserProvidedLimit(n);
   }

   public void setNoLimit(boolean on) {
     queryProcessor.setNoLimit(on);
   }

   public void setStart(int n) {
     queryProcessor.setStart(n);
   }

   public void setIncludePatchSets(boolean on) {
     includePatchSets = on;
   }

   public boolean getIncludePatchSets() {
     return includePatchSets;
   }

   public void setIncludeCurrentPatchSet(boolean on) {
     includeCurrentPatchSet = on;
   }

   public boolean getIncludeCurrentPatchSet() {
     return includeCurrentPatchSet;
   }

   public void setIncludeApprovals(boolean on) {
     includeApprovals = on;
   }

   public void setIncludeComments(boolean on) {
     includeComments = on;
   }

   public void setIncludeFiles(boolean on) {
     includeFiles = on;
   }

   public boolean getIncludeFiles() {
     return includeFiles;
   }

   public void setIncludeDependencies(boolean on) {
     includeDependencies = on;
   }

   public boolean getIncludeDependencies() {
     return includeDependencies;
   }

   public void setIncludeCommitMessage(boolean on) {
     includeCommitMessage = on;
   }

   public void setIncludeSubmitRecords(boolean on) {
     includeSubmitRecords = on;
   }

   public void setIncludeAllReviewers(boolean on) {
     includeAllReviewers = on;
   }

   public void setOutput(OutputStream out, OutputFormat fmt) {
     this.outputStream = out;
     this.outputFormat = fmt;
   }

   public void setDynamicBean(String plugin, DynamicOptions.DynamicBean dynamicBean) {
     queryProcessor.setDynamicBean(plugin, dynamicBean);
   }

   public void query(String queryString) throws IOException {
     out =
         new PrintWriter( //
             new BufferedWriter( //
                 new OutputStreamWriter(outputStream, UTF_8)));
     try {
       if (queryProcessor.isDisabled()) {
         ErrorMessage m = new ErrorMessage();
         m.message = "query disabled";
         show(m);
         return;
       }

       try {
         final QueryStatsAttribute stats = new QueryStatsAttribute();
         stats.runTimeMilliseconds = TimeUtil.nowMs();

         Map<Project.NameKey, Repository> repos = new HashMap<>();
         Map<Project.NameKey, RevWalk> revWalks = new HashMap<>();
         QueryResult<ChangeData> results = queryProcessor.query(queryBuilder.parse(queryString));
         try {
           for (ChangeData d : results.entities()) {
             show(buildChangeAttribute(d, repos, revWalks));
           }
         } finally {
           closeAll(revWalks.values(), repos.values());
         }

         stats.rowCount = results.entities().size();
         stats.moreChanges = results.more();
         stats.runTimeMilliseconds = TimeUtil.nowMs() - stats.runTimeMilliseconds;
         show(stats);
       } catch (OrmException err) {
         logger.atSevere().withCause(err).log("Cannot execute query: %s", queryString);

         ErrorMessage m = new ErrorMessage();
         m.message = "cannot query database";
         show(m);

       } catch (QueryParseException e) {
         ErrorMessage m = new ErrorMessage();
         m.message = e.getMessage();
         show(m);
       }
     } finally {
       try {
         out.flush();
       } finally {
         out = null;
       }
     }
   }

   private ChangeAttribute buildChangeAttribute(
       ChangeData d, Map<Project.NameKey, Repository> repos, Map<Project.NameKey, RevWalk> revWalks)
       throws OrmException, IOException {
     LabelTypes labelTypes = d.getLabelTypes();
     ChangeAttribute c = eventFactory.asChangeAttribute(d.change(), d.notes());
     eventFactory.extend(c, d.change());

     if (!trackingFooters.isEmpty()) {
       eventFactory.addTrackingIds(c, d.trackingFooters());
     }

     if (includeAllReviewers) {
       eventFactory.addAllReviewers(c, d.notes());
     }

     if (includeSubmitRecords) {
       SubmitRuleOptions options = SubmitRuleOptions.builder().allowClosed(true).build();
       eventFactory.addSubmitRecords(c, submitRuleEvaluatorFactory.create(options).evaluate(d));
     }

     if (includeCommitMessage) {
       eventFactory.addCommitMessage(c, d.commitMessage());
     }

     RevWalk rw = null;
     if (includePatchSets || includeCurrentPatchSet || includeDependencies) {
       Project.NameKey p = d.change().getProject();
       rw = revWalks.get(p);
       // Cache and reuse repos and revwalks.
       if (rw == null) {
         Repository repo = repoManager.openRepository(p);
         checkState(repos.put(p, repo) == null);
         rw = new RevWalk(repo);
         revWalks.put(p, rw);
       }
     }

     if (includePatchSets) {
       eventFactory.addPatchSets(
           rw,
           c,
           d.patchSets(),
           includeApprovals ? d.approvals().asMap() : null,
           includeFiles,
           d.change(),
           labelTypes);
     }

     if (includeCurrentPatchSet) {
       PatchSet current = d.currentPatchSet();
       if (current != null) {
         c.currentPatchSet = eventFactory.asPatchSetAttribute(rw, d.change(), current);
         eventFactory.addApprovals(c.currentPatchSet, d.currentApprovals(), labelTypes);

         if (includeFiles) {
           eventFactory.addPatchSetFileNames(c.currentPatchSet, d.change(), d.currentPatchSet());
         }
         if (includeComments) {
           eventFactory.addPatchSetComments(c.currentPatchSet, d.publishedComments());
         }
       }
     }

     if (includeComments) {
       eventFactory.addComments(c, d.messages());
       if (includePatchSets) {
         eventFactory.addPatchSets(
             rw,
             c,
             d.patchSets(),
             includeApprovals ? d.approvals().asMap() : null,
             includeFiles,
             d.change(),
             labelTypes);
         for (PatchSetAttribute attribute : c.patchSets) {
           eventFactory.addPatchSetComments(attribute, d.publishedComments());
         }
       }
     }

     if (includeDependencies) {
       eventFactory.addDependencies(rw, c, d.change(), d.currentPatchSet());
     }

     c.plugins = queryProcessor.getAttributesFactory().create(d);
     return c;
   }

   private static void closeAll(Iterable<RevWalk> revWalks, Iterable<Repository> repos) {
     if (repos != null) {
       for (Repository repo : repos) {
         repo.close();
       }
     }
     if (revWalks != null) {
       for (RevWalk revWalk : revWalks) {
         revWalk.close();
       }
     }
   }

   private void show(Object data) {
     switch (outputFormat) {
       default:
       case TEXT:
         if (data instanceof ChangeAttribute) {
           out.print("change ");
           out.print(((ChangeAttribute) data).id);
           out.print("\n");
           showText(data, 1);
         } else {
           showText(data, 0);
         }
         out.print('\n');
         break;

       case JSON:
         out.print(GSON.toJson(data));
         out.print('\n');
         break;
     }
   }

   private void showText(Object data, int depth) {
     for (Field f : fieldsOf(data.getClass())) {
       Object val;
       try {
         val = f.get(data);
       } catch (IllegalArgumentException err) {
         continue;
       } catch (IllegalAccessException err) {
         continue;
       }
       if (val == null) {
         continue;
       }

       showField(f.getName(), val, depth);
     }
   }

   private String indent(int spaces) {
     if (spaces == 0) {
       return "";
     }
     return String.format("%" + spaces + "s", " ");
   }

   private void showField(String field, Object value, int depth) {
     final int spacesDepthRatio = 2;
     String indent = indent(depth * spacesDepthRatio);
     out.print(indent);
     out.print(field);
     out.print(':');
     if (value instanceof String && ((String) value).contains("\n")) {
       out.print(' ');
       // Idention for multi-line text is
       // current depth indetion + length of field + length of ": "
       indent = indent(indent.length() + field.length() + spacesDepthRatio);
       out.print(((String) value).replace("\n", "\n" + indent).trim());
       out.print('\n');
     } else if (value instanceof Long && isDateField(field)) {
       out.print(' ');
       out.print(dtf.format(Instant.ofEpochSecond((Long) value)));
       out.print('\n');
     } else if (isPrimitive(value)) {
       out.print(' ');
       out.print(value);
       out.print('\n');
     } else if (value instanceof Collection) {
       out.print('\n');
       boolean firstElement = true;
       for (Object thing : ((Collection<?>) value)) {
         // The name of the collection was initially printed at the beginning
         // of this routine.  Beginning at the second sub-element, reprint
         // the collection name so humans can separate individual elements
         // with less strain and error.
         //
         if (firstElement) {
           firstElement = false;
         } else {
           out.print(indent);
           out.print(field);
           out.print(":\n");
         }
         if (isPrimitive(thing)) {
           out.print(' ');
           out.print(value);
           out.print('\n');
         } else {
           showText(thing, depth + 1);
         }
       }
     } else {
       out.print('\n');
       showText(value, depth + 1);
     }
   }

   private static boolean isPrimitive(Object value) {
     return value instanceof String //
         || value instanceof Number //
         || value instanceof Boolean //
         || value instanceof Enum;
   }

   private static boolean isDateField(String name) {
     return "lastUpdated".equals(name) //
         || "grantedOn".equals(name) //
         || "timestamp".equals(name) //
         || "createdOn".equals(name);
   }

   private List<Field> fieldsOf(Class<?> type) {
     List<Field> r = new ArrayList<>();
     if (type.getSuperclass() != null) {
       r.addAll(fieldsOf(type.getSuperclass()));
     }
     r.addAll(Arrays.asList(type.getDeclaredFields()));
     return r;
   }

   static class ErrorMessage {
     public final String type = "error";
     public String message;
   }
 }
	// Copyright (C) 2014 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.server.query.change;

	import static com.google.common.base.Preconditions.checkState;
	import static java.nio.charset.StandardCharsets.UTF_8;

	import com.google.common.flogger.FluentLogger;
	import com.google.gerrit.common.data.LabelTypes;
	import com.google.gerrit.index.query.QueryParseException;
	import com.google.gerrit.index.query.QueryResult;
	import com.google.gerrit.reviewdb.client.PatchSet;
	import com.google.gerrit.reviewdb.client.Project;
	import com.google.gerrit.server.DynamicOptions;
	import com.google.gerrit.server.config.TrackingFooters;
	import com.google.gerrit.server.data.ChangeAttribute;
	import com.google.gerrit.server.data.PatchSetAttribute;
	import com.google.gerrit.server.data.QueryStatsAttribute;
	import com.google.gerrit.server.events.EventFactory;
	import com.google.gerrit.server.git.GitRepositoryManager;
	import com.google.gerrit.server.project.SubmitRuleEvaluator;
	import com.google.gerrit.server.project.SubmitRuleOptions;
	import com.google.gerrit.server.util.time.TimeUtil;
	import com.google.gson.Gson;
	import com.google.gwtorm.server.OrmException;
	import com.google.inject.Inject;
	import java.io.BufferedWriter;
	import java.io.IOException;
	import java.io.OutputStream;
	import java.io.OutputStreamWriter;
	import java.io.PrintWriter;
	import java.lang.reflect.Field;
	import java.time.Instant;
	import java.time.ZoneId;
	import java.time.format.DateTimeFormatter;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.Collection;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Locale;
	import java.util.Map;
	import org.eclipse.jgit.lib.Repository;
	import org.eclipse.jgit.revwalk.RevWalk;
	import org.eclipse.jgit.util.io.DisabledOutputStream;

	/**
	* Change query implementation that outputs to a stream in the style of an SSH command.
	*
	* <p>Instances are one-time-use. Other singleton classes should inject a Provider rather than
	* holding on to a single instance.
	*/
	public class OutputStreamQuery {
	private static final FluentLogger logger = FluentLogger.forEnclosingClass();

	private static final DateTimeFormatter dtf =
	DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss zzz")
	.withLocale(Locale.US)
	.withZone(ZoneId.systemDefault());

	public enum OutputFormat {
	TEXT,
	JSON
	}

	public static final Gson GSON = new Gson();

	private final GitRepositoryManager repoManager;
	private final ChangeQueryBuilder queryBuilder;
	private final ChangeQueryProcessor queryProcessor;
	private final EventFactory eventFactory;
	private final TrackingFooters trackingFooters;
	private final SubmitRuleEvaluator.Factory submitRuleEvaluatorFactory;

	private OutputFormat outputFormat = OutputFormat.TEXT;
	private boolean includePatchSets;
	private boolean includeCurrentPatchSet;
	private boolean includeApprovals;
	private boolean includeComments;
	private boolean includeFiles;
	private boolean includeCommitMessage;
	private boolean includeDependencies;
	private boolean includeSubmitRecords;
	private boolean includeAllReviewers;

	private OutputStream outputStream = DisabledOutputStream.INSTANCE;
	private PrintWriter out;

	@Inject
	OutputStreamQuery(
	GitRepositoryManager repoManager,
	ChangeQueryBuilder queryBuilder,
	ChangeQueryProcessor queryProcessor,
	EventFactory eventFactory,
	TrackingFooters trackingFooters,
	SubmitRuleEvaluator.Factory submitRuleEvaluatorFactory) {
	this.repoManager = repoManager;
	this.queryBuilder = queryBuilder;
	this.queryProcessor = queryProcessor;
	this.eventFactory = eventFactory;
	this.trackingFooters = trackingFooters;
	this.submitRuleEvaluatorFactory = submitRuleEvaluatorFactory;
	}

	void setLimit(int n) {
	queryProcessor.setUserProvidedLimit(n);
	}

	public void setNoLimit(boolean on) {
	queryProcessor.setNoLimit(on);
	}

	public void setStart(int n) {
	queryProcessor.setStart(n);
	}

	public void setIncludePatchSets(boolean on) {
	includePatchSets = on;
	}

	public boolean getIncludePatchSets() {
	return includePatchSets;
	}

	public void setIncludeCurrentPatchSet(boolean on) {
	includeCurrentPatchSet = on;
	}

	public boolean getIncludeCurrentPatchSet() {
	return includeCurrentPatchSet;
	}

	public void setIncludeApprovals(boolean on) {
	includeApprovals = on;
	}

	public void setIncludeComments(boolean on) {
	includeComments = on;
	}

	public void setIncludeFiles(boolean on) {
	includeFiles = on;
	}

	public boolean getIncludeFiles() {
	return includeFiles;
	}

	public void setIncludeDependencies(boolean on) {
	includeDependencies = on;
	}

	public boolean getIncludeDependencies() {
	return includeDependencies;
	}

	public void setIncludeCommitMessage(boolean on) {
	includeCommitMessage = on;
	}

	public void setIncludeSubmitRecords(boolean on) {
	includeSubmitRecords = on;
	}

	public void setIncludeAllReviewers(boolean on) {
	includeAllReviewers = on;
	}

	public void setOutput(OutputStream out, OutputFormat fmt) {
	this.outputStream = out;
	this.outputFormat = fmt;
	}

	public void setDynamicBean(String plugin, DynamicOptions.DynamicBean dynamicBean) {
	queryProcessor.setDynamicBean(plugin, dynamicBean);
	}

	public void query(String queryString) throws IOException {
	out =
	new PrintWriter( //
	new BufferedWriter( //
	new OutputStreamWriter(outputStream, UTF_8)));
	try {
	if (queryProcessor.isDisabled()) {
	ErrorMessage m = new ErrorMessage();
	m.message = "query disabled";
	show(m);
	return;
	}

	try {
	final QueryStatsAttribute stats = new QueryStatsAttribute();
	stats.runTimeMilliseconds = TimeUtil.nowMs();

	Map<Project.NameKey, Repository> repos = new HashMap<>();
	Map<Project.NameKey, RevWalk> revWalks = new HashMap<>();
	QueryResult<ChangeData> results = queryProcessor.query(queryBuilder.parse(queryString));
	try {
	for (ChangeData d : results.entities()) {
	show(buildChangeAttribute(d, repos, revWalks));
	}
	} finally {
	closeAll(revWalks.values(), repos.values());
	}

	stats.rowCount = results.entities().size();
	stats.moreChanges = results.more();
	stats.runTimeMilliseconds = TimeUtil.nowMs() - stats.runTimeMilliseconds;
	show(stats);
	} catch (OrmException err) {
	logger.atSevere().withCause(err).log("Cannot execute query: %s", queryString);

	ErrorMessage m = new ErrorMessage();
	m.message = "cannot query database";
	show(m);

	} catch (QueryParseException e) {
	ErrorMessage m = new ErrorMessage();
	m.message = e.getMessage();
	show(m);
	}
	} finally {
	try {
	out.flush();
	} finally {
	out = null;
	}
	}
	}

	private ChangeAttribute buildChangeAttribute(
	ChangeData d, Map<Project.NameKey, Repository> repos, Map<Project.NameKey, RevWalk> revWalks)
	throws OrmException, IOException {
	LabelTypes labelTypes = d.getLabelTypes();
	ChangeAttribute c = eventFactory.asChangeAttribute(d.change(), d.notes());
	eventFactory.extend(c, d.change());

	if (!trackingFooters.isEmpty()) {
	eventFactory.addTrackingIds(c, d.trackingFooters());
	}

	if (includeAllReviewers) {
	eventFactory.addAllReviewers(c, d.notes());
	}

	if (includeSubmitRecords) {
	SubmitRuleOptions options = SubmitRuleOptions.builder().allowClosed(true).build();
	eventFactory.addSubmitRecords(c, submitRuleEvaluatorFactory.create(options).evaluate(d));
	}

	if (includeCommitMessage) {
	eventFactory.addCommitMessage(c, d.commitMessage());
	}

	RevWalk rw = null;
	if (includePatchSets \|\| includeCurrentPatchSet \|\| includeDependencies) {
	Project.NameKey p = d.change().getProject();
	rw = revWalks.get(p);
	// Cache and reuse repos and revwalks.
	if (rw == null) {
	Repository repo = repoManager.openRepository(p);
	checkState(repos.put(p, repo) == null);
	rw = new RevWalk(repo);
	revWalks.put(p, rw);
	}
	}

	if (includePatchSets) {
	eventFactory.addPatchSets(
	rw,
	c,
	d.patchSets(),
	includeApprovals ? d.approvals().asMap() : null,
	includeFiles,
	d.change(),
	labelTypes);
	}

	if (includeCurrentPatchSet) {
	PatchSet current = d.currentPatchSet();
	if (current != null) {
	c.currentPatchSet = eventFactory.asPatchSetAttribute(rw, d.change(), current);
	eventFactory.addApprovals(c.currentPatchSet, d.currentApprovals(), labelTypes);

	if (includeFiles) {
	eventFactory.addPatchSetFileNames(c.currentPatchSet, d.change(), d.currentPatchSet());
	}
	if (includeComments) {
	eventFactory.addPatchSetComments(c.currentPatchSet, d.publishedComments());
	}
	}
	}

	if (includeComments) {
	eventFactory.addComments(c, d.messages());
	if (includePatchSets) {
	eventFactory.addPatchSets(
	rw,
	c,
	d.patchSets(),
	includeApprovals ? d.approvals().asMap() : null,
	includeFiles,
	d.change(),
	labelTypes);
	for (PatchSetAttribute attribute : c.patchSets) {
	eventFactory.addPatchSetComments(attribute, d.publishedComments());
	}
	}
	}

	if (includeDependencies) {
	eventFactory.addDependencies(rw, c, d.change(), d.currentPatchSet());
	}

	c.plugins = queryProcessor.getAttributesFactory().create(d);
	return c;
	}

	private static void closeAll(Iterable<RevWalk> revWalks, Iterable<Repository> repos) {
	if (repos != null) {
	for (Repository repo : repos) {
	repo.close();
	}
	}
	if (revWalks != null) {
	for (RevWalk revWalk : revWalks) {
	revWalk.close();
	}
	}
	}

	private void show(Object data) {
	switch (outputFormat) {
	default:
	case TEXT:
	if (data instanceof ChangeAttribute) {
	out.print("change ");
	out.print(((ChangeAttribute) data).id);
	out.print("\n");
	showText(data, 1);
	} else {
	showText(data, 0);
	}
	out.print('\n');
	break;

	case JSON:
	out.print(GSON.toJson(data));
	out.print('\n');
	break;
	}
	}

	private void showText(Object data, int depth) {
	for (Field f : fieldsOf(data.getClass())) {
	Object val;
	try {
	val = f.get(data);
	} catch (IllegalArgumentException err) {
	continue;
	} catch (IllegalAccessException err) {
	continue;
	}
	if (val == null) {
	continue;
	}

	showField(f.getName(), val, depth);
	}
	}

	private String indent(int spaces) {
	if (spaces == 0) {
	return "";
	}
	return String.format("%" + spaces + "s", " ");
	}

	private void showField(String field, Object value, int depth) {
	final int spacesDepthRatio = 2;
	String indent = indent(depth * spacesDepthRatio);
	out.print(indent);
	out.print(field);
	out.print(':');
	if (value instanceof String && ((String) value).contains("\n")) {
	out.print(' ');
	// Idention for multi-line text is
	// current depth indetion + length of field + length of ": "
	indent = indent(indent.length() + field.length() + spacesDepthRatio);
	out.print(((String) value).replace("\n", "\n" + indent).trim());
	out.print('\n');
	} else if (value instanceof Long && isDateField(field)) {
	out.print(' ');
	out.print(dtf.format(Instant.ofEpochSecond((Long) value)));
	out.print('\n');
	} else if (isPrimitive(value)) {
	out.print(' ');
	out.print(value);
	out.print('\n');
	} else if (value instanceof Collection) {
	out.print('\n');
	boolean firstElement = true;
	for (Object thing : ((Collection<?>) value)) {
	// The name of the collection was initially printed at the beginning
	// of this routine. Beginning at the second sub-element, reprint
	// the collection name so humans can separate individual elements
	// with less strain and error.
	//
	if (firstElement) {
	firstElement = false;
	} else {
	out.print(indent);
	out.print(field);
	out.print(":\n");
	}
	if (isPrimitive(thing)) {
	out.print(' ');
	out.print(value);
	out.print('\n');
	} else {
	showText(thing, depth + 1);
	}
	}
	} else {
	out.print('\n');
	showText(value, depth + 1);
	}
	}

	private static boolean isPrimitive(Object value) {
	return value instanceof String //
	\|\| value instanceof Number //
	\|\| value instanceof Boolean //
	\|\| value instanceof Enum;
	}

	private static boolean isDateField(String name) {
	return "lastUpdated".equals(name) //
	\|\| "grantedOn".equals(name) //
	\|\| "timestamp".equals(name) //
	\|\| "createdOn".equals(name);
	}

	private List<Field> fieldsOf(Class<?> type) {
	List<Field> r = new ArrayList<>();
	if (type.getSuperclass() != null) {
	r.addAll(fieldsOf(type.getSuperclass()));
	}
	r.addAll(Arrays.asList(type.getDeclaredFields()));
	return r;
	}

	static class ErrorMessage {
	public final String type = "error";
	public String message;
	}
	}