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/*
* Copyright (c) 2020 Contributors to the Eclipse Foundation
*
* See the NOTICE file(s) distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0, or the Eclipse Distribution License 1.0
* which is available at http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
*/
package org.eclipse.lyo.oslc4j.trs.server;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.List;
import java.util.Objects;
import java.util.UUID;
import java.util.concurrent.atomic.AtomicLong;
import org.eclipse.lyo.core.trs.Base;
import org.eclipse.lyo.core.trs.ChangeEvent;
import org.eclipse.lyo.core.trs.ChangeLog;
import org.eclipse.lyo.core.trs.Creation;
import org.eclipse.lyo.core.trs.Deletion;
import org.eclipse.lyo.core.trs.Modification;
import org.eclipse.lyo.core.trs.Page;
import org.eclipse.lyo.core.trs.TRSConstants;
import org.eclipse.lyo.oslc4j.core.model.IResource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import jakarta.ws.rs.core.UriBuilder;
/**
* This class is the backbone of the Tracked resource set service class. This class is extended by
* oslc adapters wishing to implement an OSLC TRS interface. The implementing classes need to
* implement one method returning the change history of the resources living in the tool exposed by
* the OSLC adapter
*
* @version $version-stub$
* @since 2.3.0
*/
public class InmemPagedTrs implements PagedTrs, TrsEventHandler {
private final static Logger log = LoggerFactory.getLogger(InmemPagedTrs.class);
/**
* Max items per changelog Page
*/
private final int changelogPageLimit;
/**
* Base in 'uriBase' has nothing to do with the TRS Base.
*/
private final URI uriBase;
private final AtomicLong trsOrderId = new AtomicLong();
/**
* Max items per base Page
*/
private final int basePageLimit;
/**
* The relative path of the base, may contain URI template parameters.
*/
private final String baseRelativePath;
/**
* The relative path of the changeLog, may contain URI template parameters.
*/
private final String changeLogRelativePath;
/**
* List of base resources
*/
private final List baseResources = new ArrayList<>();
/**
* List of Change Logs
*/
private final List changelogResources = new ArrayList<>();
/**
* @param basePageLimit Max items per Base page
* @param changelogPageLimit Max items per Changelog page
* @param uriBase Set it via eg
* @param baseRelativePath The relative path of the base, may contain URI template parameters.
* @param changeLogRelativePath The relative path of the changeLog, may contain URI template parameters.
* @param baseResourceUris Initial set of the TRS Base resource URIs
*/
public InmemPagedTrs(final int basePageLimit, final int changelogPageLimit, final URI uriBase,
final String baseRelativePath, final String changeLogRelativePath, final Collection baseResourceUris) {
this.basePageLimit = basePageLimit;
this.changelogPageLimit = changelogPageLimit;
this.uriBase = uriBase;
this.baseRelativePath = baseRelativePath;
this.changeLogRelativePath = changeLogRelativePath;
initBase(baseResourceUris);
}
/**
* @param basePageLimit Max items per Base page
* @param changelogPageLimit Max items per Changelog page
* @param uriBase Set it via eg
* @param baseResourceUris Initial set of the TRS Base resource URIs
*/
public InmemPagedTrs(final int basePageLimit, final int changelogPageLimit, final URI uriBase,
final Collection baseResourceUris) {
this.basePageLimit = basePageLimit;
this.changelogPageLimit = changelogPageLimit;
this.uriBase = uriBase;
this.baseRelativePath = "base";
this.changeLogRelativePath = "changelog";
initBase(baseResourceUris);
}
@Override
public Base getBaseResource(final Integer pageId) {
int listIdx = pageIdToListIdx(pageId);
if (listIdx < 0 || listIdx >= baseResources.size()) {
throw new IllegalArgumentException("There is no such Base page");
}
return baseResources.get(listIdx);
}
private int pageIdToListIdx(final Integer pageId) {
return pageId - 1;
}
@Override
public int basePageCount() {
return baseResources.size();
}
@Override
public ChangeLog getChangeLog(final Integer pageId) {
int listIdx = pageIdToListIdx(pageId);
if (listIdx < 0 || listIdx >= changelogResources.size()) {
throw new IllegalArgumentException("There is no such ChangeLog page");
}
return changelogResources.get(listIdx);
}
@Override
public ChangeLog getChangeLogLast() {
return getChangeLog(changelogPageCount());
}
@Override
public int changelogPageCount() {
return changelogResources.size();
}
@Override
public void onCreated(final IResource resource) {
final HistoryData instance = HistoryData.getInstance(new Date(), resource.getAbout(),
HistoryData.CREATED);
onHistoryData(instance);
}
@Override
public void onModified(final IResource resource) {
final HistoryData instance = HistoryData.getInstance(new Date(), resource.getAbout(),
HistoryData.MODIFIED);
onHistoryData(instance);
}
@Override
public void onDeleted(final URI resourceUri) {
final HistoryData instance = HistoryData.getInstance(new Date(), resourceUri,
HistoryData.DELETED);
onHistoryData(instance);
}
public void onHistoryData(final HistoryData event) {
final ChangeLog changeLog = findOrCreateChangelogPage();
final ChangeEvent changeEvent = createChangeEvent(event);
changeLog.getChange().add(changeEvent);
}
private ChangeEvent createChangeEvent(final long changeOrder, final URI trackedResourceUri,
final URI eventUri, final String histDataType) {
final ChangeEvent ce;
if (changeOrder >= Integer.MAX_VALUE) {
throw new IllegalStateException("Switch ChangeEvents to use longs");
}
if (Objects.equals(histDataType, HistoryData.CREATED)) {
ce = new Creation(eventUri, trackedResourceUri, (int) changeOrder);
} else if (Objects.equals(histDataType, HistoryData.MODIFIED)) {
ce = new Modification(eventUri, trackedResourceUri, (int) changeOrder);
} else if (Objects.equals(histDataType, HistoryData.DELETED)) {
ce = new Deletion(eventUri, trackedResourceUri, (int) changeOrder);
} else {
log.error("Change Event {} has unknown kind: {}", trackedResourceUri, histDataType);
throw new IllegalArgumentException();
}
return ce;
}
private ChangeEvent createChangeEvent(final HistoryData event) {
final long order = nextCutoff();
final URI ceUri = createUuidUrn();
if (order >= Integer.MAX_VALUE) {
throw new IllegalStateException("Switch ChangeEvents to use longs");
}
return createChangeEvent((int) order, event.getUri(), ceUri, event.getType());
}
private void initBase(final Collection baseResourceUris) {
Base base = this.findOrCreateBase();
int remainingResources = calcRemainingResources(base);
for (final URI resourceUris : baseResourceUris) {
if (remainingResources < 1) {
base = this.findOrCreateBase();
remainingResources = calcRemainingResources(base);
}
base.getMembers().add(resourceUris);
remainingResources -= 1;
}
}
private Base findOrCreateBase() {
final Base page;
if (this.baseResources.isEmpty()) {
page = createBase();
} else {
final Base lastBase = getLastBaseResource();
if (isBaseFull(lastBase)) {
page = createBase();
lastBase.getNextPage().setNextPage(page.getNextPage().getAbout());
} else {
page = lastBase;
}
}
// using single-return style to benefit from the 'final' check
return page;
}
/**
* Create a new page object with the page basepagenum
*
* @return the created base page object
*/
private Base createBase() {
final Base base = new Base();
base.setAbout(this.createBaseUri());
base.setNextPage(createBasePage(base, nextBasePageId()));
base.setCutoffEvent(URI.create(TRSConstants.RDF_NIL));
log.debug("Adding a new Base resource");
baseResources.add(base);
return base;
}
/**
* Create the page attribute of the base object
*
* @param base the base object for which this is the page
* @param pageId number of the page
*
* @return the page of the base
*/
private Page createBasePage(final Base base, final int pageId) {
final Page basePage = new Page();
basePage.setAbout(this.createBasePageUri(pageId));
basePage.setNextPage(URI.create(TRSConstants.RDF_NIL));
basePage.setPageOf(base);
return basePage;
}
//the last page of the changeLog's URI is set to null, since it needs to be a local resource in the trackedResourceSet.
//All other pages will have a URI
private ChangeLog findOrCreateChangelogPage() {
final ChangeLog page;
if (this.changelogResources.isEmpty()) {
page = createChangelogPage(TRSUtil.NIL_URI, null);
} else {
final ChangeLog lastPage = getLastChangelogPage();
if (isChangelogPageFull(lastPage)) {
lastPage.setAbout(createChangelogUri());
page = createChangelogPage(lastPage.getAbout(), null);
} else {
page = lastPage;
}
}
// using single-return style to benefit from the 'final' check
return page;
}
private ChangeLog createChangelogPage(final URI previous, final URI current) {
final ChangeLog changelog = new ChangeLog();
changelog.setAbout(current);
changelog.setPrevious(previous);
changelogResources.add(changelog);
return changelog;
}
private int calcRemainingResources(final Base base) {
final int remaining = basePageLimit - base.getMembers().size();
if (remaining < 0) {
log.warn("Base contains more resources than it should!");
}
return Math.max(remaining, 0);
}
private boolean isBaseFull(final Base base) {
return calcRemainingResources(base) == 0;
}
private boolean isChangelogPageFull(final ChangeLog changeLog) {
return changeLog.getChange().size() >= changelogPageLimit;
}
private ChangeLog getLastChangelogPage() {
return this.changelogResources.get(this.changelogResources.size() - 1);
}
private int nextBasePageId() {
return basePageIdFor(this.baseResources.size());
}
private int basePageIdFor(final int listIdx) {
return listIdx + 1;
}
private Base getLastBaseResource() {
return this.baseResources.get(this.baseResources.size() - 1);
}
private URI createBaseUri() {
final URI uri = getUriBuilder().path(this.baseRelativePath).build();
return uri;
}
private URI createBasePageUri(final int pageId) {
final URI uri = getUriBuilder().path(this.baseRelativePath).path(String.valueOf(pageId)).build();
return uri;
}
private URI createChangelogUri() {
final int nextPageId = this.changelogResources.size();
final URI uri = getUriBuilder().path(this.changeLogRelativePath).path(String.valueOf(nextPageId)).build();
return uri;
}
private long nextCutoff() {
final long next = trsOrderId.incrementAndGet();
return next;
}
private UriBuilder getUriBuilder() {
return UriBuilder.fromUri(uriBase);
}
private URI createUuidUrn() {
return URI.create(String.format("urn:uuid:%s", UUID.randomUUID().toString()));
}
}
