Checkpoint checkin of patch code.

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@2119 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/admin/patch/AbstractPatch.java

@@ -0,0 +1,232 @@
+/*
+ * Copyright (C) 2005 Alfresco, Inc.
+ *
+ * Licensed under the Mozilla Public License version 1.1 
+ * with a permitted attribution clause. You may obtain a
+ * copy of the License at
+ *
+ *   http://www.alfresco.org/legal/license.txt
+ *
+ * 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 org.alfresco.repo.admin.patch;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.util.Collections;
+import java.util.List;
+
+import org.alfresco.error.AlfrescoRuntimeException;
+import org.alfresco.repo.transaction.TransactionUtil;
+import org.alfresco.repo.transaction.TransactionUtil.TransactionWork;
+import org.alfresco.service.cmr.admin.PatchException;
+import org.alfresco.service.transaction.TransactionService;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+/**
+ * Base implementation of the patch.  This class ensures that the patch is
+ * thread- and transaction-safe.
+ * 
+ * @author Derek Hulley
+ */
+public abstract class AbstractPatch implements Patch
+{
+    private static Log logger = LogFactory.getLog(AbstractPatch.class);
+    
+    private String id;
+    private String applyAfterVersion;
+    private String description;
+    /** a list of patches that this one depends on */
+    private List<Patch> dependsOn;
+    /** flag indicating if the patch was successfully applied */
+    private boolean applied;
+    private TransactionService transactionService;
+
+    public AbstractPatch()
+    {
+        this.applied = false;
+        this.dependsOn = Collections.emptyList();
+    }
+    
+    @Override
+    public String toString()
+    {
+        StringBuilder sb = new StringBuilder(56);
+        sb.append("Patch")
+          .append("[id=").append(getId())
+          .append(", after=").append(getApplyAfterVersion())
+          .append(", description=").append(getDescription())
+          .append("]");
+        return sb.toString();
+    }
+    
+    /**
+     * Set the transaction provider so that each execution can be performed within a transaction
+     */
+    public void setTransactionService(TransactionService transactionService)
+    {
+        this.transactionService = transactionService;
+    }
+    
+    public String getId()
+    {
+        return id;
+    }
+
+    /**
+     * 
+     * @param id the unique ID of the patch.  This dictates the order in which patches are applied.
+     */
+    public void setId(String id)
+    {
+        this.id = id;
+    }
+
+    public String getApplyAfterVersion()
+    {
+        return applyAfterVersion;
+    }
+
+    /**
+     * 
+     * @param applyAfterVersion the version of the repository after which this patch must be applied.
+     */
+    public void setApplyAfterVersion(String applyAfterVersion)
+    {
+        this.applyAfterVersion = applyAfterVersion;
+    }
+
+    public String getDescription()
+    {
+        return description;
+    }
+
+    /**
+     * @param description a thorough description of the patch
+     */
+    public void setDescription(String description)
+    {
+        this.description = description;
+    }
+
+    public List<Patch> getDependsOn()
+    {
+        return this.dependsOn;
+    }
+    /**
+     * Set all the dependencies for this patch.  It should not be executed
+     * before all the dependencies have been applied.
+     * 
+     * @param dependsOn a list of dependencies
+     */
+    public void setDependsOn(List<Patch> dependsOn)
+    {
+        this.dependsOn = dependsOn;
+    }
+
+    /**
+     * Sets up the transaction and ensures thread-safety.
+     * 
+     * @see #applyInternal()
+     */
+    public synchronized String apply() throws PatchException
+    {
+        // ensure that this has not been executed already
+        if (applied)
+        {
+            throw new AlfrescoRuntimeException("The patch has already been executed: \n" +
+                    "   patch: " + this);
+        }
+        // check that the necessary properties have been set
+        if (id == null || applyAfterVersion == null || description == null)
+        {
+            throw new AlfrescoRuntimeException(
+                    "Patch properties 'id', 'applyAfterVersion' and 'description' have not all been set on this patch: \n" +
+                    "   patch: " + this);
+        }
+        else if (transactionService == null)
+        {
+            throw new AlfrescoRuntimeException("'transactionService' property has not been set: \n" +
+                    "   patch: " + this);
+        }
+        // execute in a transaction
+        try
+        {
+            TransactionWork<String> patchWork = new TransactionWork<String>()
+            {
+                public String doWork() throws Exception
+                {
+                    String report = applyInternal();
+                    // done
+                    return report;
+                };
+            };
+            String report = TransactionUtil.executeInUserTransaction(transactionService, patchWork);
+            // the patch was successfully applied
+            applied = true;
+            // done
+            if (logger.isDebugEnabled())
+            {
+                logger.debug("Patch successfully applied: \n" +
+                        "   patch: " + this + "\n" +
+                        "   report: " + report);
+            }
+            return report;
+        }
+        catch (PatchException e)
+        {
+            // no need to extract the exception
+            throw e;
+        }
+        catch (Throwable e)
+        {
+            // check whether there is an embedded patch exception
+            Throwable cause = e.getCause();
+            if (cause != null && cause instanceof PatchException)
+            {
+                throw (PatchException) cause;
+            }
+            // need to generate a message from the exception
+            String report = makeReport(e);
+            // generate the correct exception
+            throw new PatchException(report);
+        }
+    }
+    
+    /**
+     * Dumps the error's full message and trace to the String
+     * 
+     * @param e the throwable
+     * @return Returns a String representative of the printStackTrace method
+     */
+    private String makeReport(Throwable e)
+    {
+        StringWriter stringWriter = new StringWriter(1024);
+        PrintWriter printWriter = new PrintWriter(stringWriter, true);
+        try
+        {
+            e.printStackTrace(printWriter);
+            return stringWriter.toString();
+        }
+        finally
+        {
+            printWriter.close();
+        }
+    }
+
+    /**
+     * This method does the work.  All transactions and thread-safety will be taken care of by this class.
+     * Any exception will result in the transaction being rolled back.
+     * 
+     * @return Returns the report (only success messages).
+     * @see #apply()
+     * @throws Exception anything can be thrown.  This must be used for all failures.
+     */
+    protected abstract String applyInternal() throws Exception;
+}