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/**
* The contents of this file are subject to the license and copyright
* detailed in the LICENSE and NOTICE files at the root of the source
* tree and available online at
*
* http://www.dspace.org/license/
*/
package org.dspace.ctask.replicate;
import java.sql.SQLException;
import org.dspace.content.DSpaceObject;
import org.dspace.core.Constants;
import org.dspace.core.Context;
import java.io.File;
import java.io.IOException;
import org.apache.log4j.Logger;
import org.dspace.core.ConfigurationManager;
import org.dspace.core.PluginManager;
import org.dspace.handle.HandleManager;
import static org.dspace.ctask.replicate.Odometer.*;
/**
* Singleton access point for communicating with replication access providers.
* ReplicaManager adds a thin accounting or bookkeeping layer, recording
* activity with the storage provider.
*
* @author richardrodgers
*/
public class ReplicaManager {
private Logger log = Logger.getLogger(ReplicaManager.class);
// singleton instance
private static ReplicaManager instance = null;
// the replica provider
private ObjectStore objStore = null;
// base directory for replication activities
private final String repDir = ConfigurationManager.getProperty("replicate", "base.dir");
// an odometer for recording activity
private Odometer odometer = null;
// lock for updating odometer
private final Object odoLock = new Object();
// Primary store group name
private final String storeGroupName = ConfigurationManager.getProperty("replicate", "group.aip.name");
// Delete store group name
private final String deleteGroupName = ConfigurationManager.getProperty("replicate", "group.delete.name");
// Separating character between Type prefix and object identifier, used when packages are named with a Type prefix
private final String typePrefixSeparator = "@";
private ReplicaManager() throws IOException
{
objStore = (ObjectStore)PluginManager.getSinglePlugin("replicate", ObjectStore.class);
if (objStore == null) {
log.error("No ObjectStore configured in 'replicate.cfg'!");
throw new IOException("No ObjectStore configured in 'replicate.cfg'!");
}
objStore.init();
// create directory structures
new File(repDir).mkdirs();
// load our odometer - writeable copy
try
{
odometer = new Odometer(repDir, false);
}
catch (IOException ioE)
{
//just log a warning
log.warn("Unable to read odometer file in '"+ repDir + "'", ioE);
}
}
public static synchronized ReplicaManager instance() throws IOException
{
if (instance == null)
{
instance = new ReplicaManager();
}
return instance;
}
public File stage(String group, String id)
{
// ensure path exists
File stageDir = new File(repDir + File.separator + group);
if (! stageDir.isDirectory())
{
stageDir.mkdirs();
}
return new File(stageDir, storageId(id, null));
}
/**
* Determine the Identifier of an object once it is placed
* in storage. This method ensures any special characters are
* escaped. It also ensures all objects are named in a similar
* manner once they are in a given store (so that they can similarly
* be retrieved from storage using this same 'storageId').
*
* @param objId - original object id (canonical ID)
* @param fileExtension - file extension, if any (may be null)
* @return reformatted storage ID for this object (including file extension)
*/
public String storageId(String objId, String fileExtension)
{
// canonical handle notation bedevils file system semantics
String storageId = objId.replaceAll("/", "-");
// add appropriate file extension, if needed
if(fileExtension!=null)
storageId = storageId + "." + fileExtension;
// If 'packer.typeprefix' setting is 'true',
// then prefix the storageID with the DSpace Type (if it doesn't already have a prefix)
if(ConfigurationManager.getBooleanProperty("replicate", "packer.typeprefix", true) &&
!storageId.contains(typePrefixSeparator))
{
String typePrefix = null;
try
{
Context ctx = new Context();
//Get object associated with this handle
DSpaceObject dso = HandleManager.resolveToObject(ctx, objId);
ctx.complete();
//typePrefix format = 'TYPE@'
if(dso!=null)
typePrefix = Constants.typeText[dso.getType()] + typePrefixSeparator;
}
catch(SQLException sqle)
{
//do nothing, just ignore -- we'll handle this in a moment
}
// If we were unable to determine a type prefix, then this must mean the object
// no longer exists in DSpace! Let's see if we can find it in storage!
if(typePrefix==null)
{
try
{
//Currently we need to try and lookup the object in storage
//Hopefully, there will be an easier way to do this in the future
//see if this object exists in main storage group
typePrefix = findTypePrefix(storeGroupName, storageId);
if(typePrefix==null && deleteGroupName!=null) //if not found, check deletion group as well
typePrefix = findTypePrefix(deleteGroupName, storageId);
}
catch(IOException io)
{
//do nothing, just ignore
}
}
//if we found a typePrefix, prepend it on storageId
if(typePrefix!=null)
storageId = typePrefix + storageId;
}
// Return final storage ID
return storageId;
}
/**
* Convert a Storage ID back into a Canonical Identifier
* (opposite of 'storageId()' method).
* @param storageId the given object's storage ID
* @return the objects canonical identifier
*/
public String canonicalId(String storageId)
{
//If this 'storageId' includes a TYPE prefix (see 'storageId()' method),
// then remove it, before returning the reformatted ID.
if(storageId.contains(typePrefixSeparator))
storageId = storageId.substring(storageId.indexOf(typePrefixSeparator)+1);
//If this 'storageId' includes a file extension suffix, also remove it.
if(storageId.contains("."))
storageId = storageId.substring(0, storageId.indexOf("."));
//Finally revert all dashes back to slashes (to create the original canonical ID)
return storageId.replaceAll("-", "/");
}
public Odometer getOdometer() throws IOException
{
// return a new read-only copy
return new Odometer(repDir, true);
}
// Replica store-backed methods
public File fetchObject(String group, String objId) throws IOException
{
//String repId = safeId(id) + "." + arFmt;
File file = stage(group, objId);
long size = objStore.fetchObject(group, objId, file);
if (size > 0L)
{
synchronized (odoLock)
{
odometer.adjustProperty(DOWNLOADED, size);
odometer.save();
}
}
return file.exists() ? file : null;
}
public void transferObject(String group, File file) throws IOException {
String psStr = objStore.objectAttribute(group, file.getName(), "sizebytes");
long prevSize = psStr != null ? Long.valueOf(psStr) : 0L;
long size = objStore.transferObject(group, file);
if (size > 0L) {
synchronized (odoLock) {
odometer.adjustProperty(UPLOADED, size);
// this may be an update - not a new object
odometer.adjustProperty(SIZE, size - prevSize);
if (prevSize == 0L) {
odometer.adjustProperty(COUNT, 1L);
}
odometer.save();
}
}
}
public boolean objectExists(String group, String objId) throws IOException {
return objStore.objectExists(group, objId);
}
public String objectAttribute(String group, String objId, String attrName) throws IOException {
return objStore.objectAttribute(group, objId, attrName);
}
public void removeObject(String group, String objId) throws IOException {
long size = objStore.removeObject(group, objId);
if (size > 0L) {
synchronized (odoLock) {
odometer.adjustProperty(SIZE, -size);
odometer.adjustProperty(COUNT, -1L);
odometer.save();
}
}
}
/**
* This method is only called if we cannot determine an object's type prefix
* via DSpace (i.e. the object no longer exists in DSpace). In this case,
* we'll perform some basic searching of the given object store group to see
* if we can find an object with this ID that has a type prefix.
*
* @param group store group name to search
* @param baseId base object id we are looking for (without type prefix)
* @return Type prefix if a matching object is located successfully. Null otherwise.
*/
private String findTypePrefix(String group, String baseId) throws IOException
{
boolean exists = false;
// This next part may look a bit like a hack, but it's actually safer than
// it seems. Essentially, we are going to try to "guess" what the Type Prefix
// may be, and see if we can find an object with that name in our object Store.
// The reason this is still "safe" is that the "objId" should be unique with or without
// the Type prefix. Even if it wasn't unique, DSpace HandleManager has checks in place
// to ensure we can never restore an object of a different Type to a Handle that was
// used previously (e.g. cannot restore an Item with a handle that was previously used by a Collection)
// NOTE: If DSpace ever provided a way to lookup Object type for an unbound handle, then
// we may no longer need to guess which type this object may have been.
// ALTERNATIVELY: If DuraCloud & other stores provide a way to search by file properties, we could change
// our store plugins to always save the object handle as a property & retrieve files via that property.
//Most objects are Items, so lets see if this object can be found with an Item Type prefix
String typePrefix = Constants.typeText[Constants.ITEM] + typePrefixSeparator;
exists = objStore.objectExists(group, typePrefix + baseId);
if(!exists)
{
//Ok, our second guess will be that this used to be a Collection
typePrefix = Constants.typeText[Constants.COLLECTION] + typePrefixSeparator;
exists = objStore.objectExists(group, typePrefix + baseId);
}
if(!exists)
{
//Final guess: maybe this used to be a Community?
typePrefix = Constants.typeText[Constants.COMMUNITY] + typePrefixSeparator;
exists = objStore.objectExists(group, typePrefix + baseId);
}
// That's it. We're done guessing. If we still couldn't find this object,
// it obviously doesn't exist in our object Store.
if(exists)
return typePrefix;
else
return null;
}
}
