#137 introduced ProcessInstance.version; enforce it on checkin

metasfresh-webui-api/src/main/java/de/metas/ui/web/exceptions/InvalidDocumentVersionException.java

@@ -0,0 +1,34 @@
+package de.metas.ui.web.exceptions;
+
+import org.adempiere.exceptions.AdempiereException;
+
+/*
+ * #%L
+ * metasfresh-webui-api
+ * %%
+ * Copyright (C) 2017 metas GmbH
+ * %%
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program. If not, see
+ * <http://www.gnu.org/licenses/gpl-2.0.html>.
+ * #L%
+ */
+
+@SuppressWarnings("serial")
+public class InvalidDocumentVersionException extends AdempiereException
+{
+	public InvalidDocumentVersionException(final int expectedVersion, final int actualVersion)
+	{
+		super("Invalid version, expected " + expectedVersion + " but it was " + actualVersion);
+	}
+}

metasfresh-webui-api/src/main/java/de/metas/ui/web/process/ProcessInstance.java

@@ -85,8 +85,10 @@ public final class ProcessInstance
 	@Lazy
 	private IDocumentViewsRepository documentViewsRepo;
 
-	private final ProcessDescriptor processDescriptor;
 	private final DocumentId adPInstanceId;
+	private int version = 1;
+
+	private final ProcessDescriptor processDescriptor;
 	private final Document parameters;
 
 	private boolean executed = false;
@@ -114,8 +116,10 @@ private ProcessInstance(final ProcessInstance from, final CopyMode copyMode)
 		// Adempiere.autowire(this);
 		documentViewsRepo = from.documentViewsRepo;
 
-		processDescriptor = from.processDescriptor;
 		adPInstanceId = from.adPInstanceId;
+		version = from.version;
+
+		processDescriptor = from.processDescriptor;
 		parameters = from.parameters.copy(copyMode);
 
 		executed = from.executed;
@@ -128,6 +132,7 @@ public String toString()
 		return MoreObjects.toStringHelper(this)
 				.omitNullValues()
 				.add("AD_PInstance_ID", adPInstanceId)
+				.add("version", version)
 				.add("executed", "executed")
 				.add("executionResult", executionResult)
 				.add("processDescriptor", processDescriptor)
@@ -150,6 +155,16 @@ public DocumentId getAD_PInstance_ID()
 		return adPInstanceId;
 	}
 
+	/* package */int getVersion()
+	{
+		return version;
+	}
+
+	/* package */void setVersion(final int version)
+	{
+		this.version = version;
+	}
+
 	public Document getParametersDocument()
 	{
 		return parameters;

metasfresh-webui-api/src/main/java/de/metas/ui/web/process/ProcessInstancesRepository.java

@@ -1,6 +1,7 @@
 package de.metas.ui.web.process;
 
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
 
 import org.adempiere.exceptions.AdempiereException;
 import org.adempiere.util.Services;
@@ -19,6 +20,7 @@
 import de.metas.process.IADPInstanceDAO;
 import de.metas.process.ProcessDefaultParametersUpdater;
 import de.metas.process.ProcessInfo;
+import de.metas.ui.web.exceptions.InvalidDocumentVersionException;
 import de.metas.ui.web.process.descriptor.ProcessDescriptor;
 import de.metas.ui.web.process.descriptor.ProcessDescriptorsFactory;
 import de.metas.ui.web.process.descriptor.ProcessParametersRepository;
@@ -58,6 +60,7 @@ public class ProcessInstancesRepository
 	private ProcessDescriptorsFactory processDescriptorFactory;
 
 	private final LoadingCache<DocumentId, ProcessInstance> processInstances = CacheBuilder.newBuilder()
+			.expireAfterAccess(10, TimeUnit.MINUTES)
 			.removalListener(new RemovalListener<DocumentId, ProcessInstance>()
 			{
 				@Override
@@ -72,6 +75,7 @@ public void onRemoval(final RemovalNotification<DocumentId, ProcessInstance> not
 	public void cacheReset()
 	{
 		processInstances.invalidateAll();
+		processInstances.cleanUp();
 	}
 
 	public ProcessDescriptor getProcessDescriptor(final int adProcessId)
@@ -82,7 +86,34 @@ public ProcessDescriptor getProcessDescriptor(final int adProcessId)
 	public void checkin(final ProcessInstance processInstance)
 	{
 		processInstance.saveIfValidAndHasChanges(false); // throwEx=false
-		processInstances.put(processInstance.getAD_PInstance_ID(), processInstance.copy(CopyMode.CheckInReadonly));
+
+		final int versionCurrentExpected = processInstance.getVersion();
+		final int version = versionCurrentExpected + 1;
+		final ProcessInstance processInstanceCopy = processInstance.copy(CopyMode.CheckInReadonly);
+		processInstanceCopy.setVersion(version);
+		final DocumentId adPInstanceId = processInstance.getAD_PInstance_ID();
+
+		// NOTE: because Cache does not have a compute() method, we have to synchronize this block. 
+		synchronized (processInstanceCopy)
+		{
+			// Get current process instance.
+			final ProcessInstance processInstanceCurrent = processInstances.getIfPresent(adPInstanceId);
+
+			// Make sure we are not overriding a different document version than the one that was checked out.
+			if (processInstanceCurrent != null)
+			{
+				if (processInstanceCurrent.getVersion() != versionCurrentExpected)
+				{
+					throw new InvalidDocumentVersionException(versionCurrentExpected, processInstanceCurrent.getVersion());
+				}
+			}
+
+			// Actually put the new document
+			processInstances.put(adPInstanceId, processInstanceCopy);
+
+			// Update version of the document that was given as parameter.
+			processInstance.setVersion(version);
+		}
 	}
 
 	public ProcessInstance createNewProcessInstance(final ProcessInfo processInfo)
@@ -158,10 +189,10 @@ public ProcessInstance getProcessInstanceForReading(final int pinstanceIdAsInt)
 
 	public ProcessInstance getProcessInstanceForWriting(final int pinstanceIdAsInt)
 	{
+		final DocumentId documentId = DocumentId.of(pinstanceIdAsInt);
 		try
 		{
-			return processInstances.get(DocumentId.of(pinstanceIdAsInt))
-					.copy(CopyMode.CheckOutWritable);
+			return processInstances.get(documentId).copy(CopyMode.CheckOutWritable);
 		}
 		catch (final UncheckedExecutionException | ExecutionException e)
 		{