This checks in the current state of WCM development.

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/BRANCHES/WCM-DEV2/root@3128 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/avm/Issuer.java

@@ -0,0 +1,149 @@
+/*
+ * Copyright (C) 2006 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.avm;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+/**
+ * This is a helper class that knows how to issue identifiers.
+ * @author britt
+ */
+class Issuer
+{
+    /**
+     * The path to this issuers persistent storage.
+     */
+    private String fPath;
+    
+    /**
+     * The next number to issue.
+     */
+    private long fNext;
+    
+    /**
+     * Constructor for an already existing Issuer.
+     * @param path The path to this issuers persistent store.
+     */
+    public Issuer(String path)
+    {
+        fPath = path;
+        try
+        {
+            DataInputStream in = new DataInputStream(new FileInputStream(fPath + ".new"));
+            fNext = in.readLong();
+            fNext += 257;
+            in.close();
+            save();
+            return;
+        }
+        catch (IOException ie)
+        {
+            // Do nothing.
+        }
+        try
+        {
+            DataInputStream in = new DataInputStream(new FileInputStream(fPath));
+            fNext = in.readLong();
+            fNext += 257;
+            in.close();
+            save();
+            return;
+        }
+        catch (IOException ie)
+        {
+            // Do nothing.
+        }
+        // Last resort.
+        try
+        {
+            DataInputStream in = new DataInputStream(new FileInputStream(fPath + ".old"));
+            fNext = in.readLong();
+            fNext += 513;
+            in.close();
+            save();
+            return;
+        }
+        catch (IOException ie)
+        {
+            // TODO Log this situation.
+            throw new AVMException("Could not restore issuer" + fPath, ie);
+        }
+    }
+            
+    /**
+     * Rich constructor.
+     * @param path The path to this issuers persistent store.
+     * @param next The next number to issue.
+     */
+    public Issuer(String path, long next)
+    {
+        fPath = path;
+        fNext = next;
+        save();
+    }
+    
+    /**
+     * Issue the next number.
+     * @return A serial number.
+     */
+    public synchronized long issue()
+    {
+        long val = fNext++;
+        if (fNext % 128 == 0)
+        {
+            save();
+        }
+        return val;
+    }
+    
+    /**
+     * Persist this issuer.
+     */
+    public void save()
+    {
+        while (true)
+        {
+            try
+            {
+                FileOutputStream fileOut = new FileOutputStream(fPath + ".new");
+                DataOutputStream out = new DataOutputStream(fileOut);
+                out.writeLong(fNext);
+                out.flush();
+                // Force data to physical storage.
+                fileOut.getChannel().force(true);
+                out.close();
+                File from = new File(fPath);
+                File to = new File(fPath + ".old");
+                from.renameTo(to);
+                from = new File(fPath + ".new");
+                to = new File(fPath);
+                from.renameTo(to);
+                break;
+            }
+            catch (IOException ie)
+            {
+                // TODO Log this situation.
+            }
+        }
+    }                
+}