/**
* Look up and return the ClassInfo for a class. This is used when encoding an <code>Object</code>
* into a <code>com.persistit.Value</code>.
*
* @param clazz The <code>Class</code>
* @return The ClassInfo for the specified Class.
*/
public ClassInfo lookupByClass(final Class<?> clazz) {
final AtomicReferenceArray<ClassInfoEntry> hashTable = _hashTable;
ObjectStreamClass osc = null;
long suid = 0;
final int nh = clazz.getName().hashCode() & 0x7FFFFFFF;
ClassInfoEntry cie = hashTable.get(nh % hashTable.length());
while (cie != null) {
if (clazz.equals(cie._classInfo.getDescribedClass())) {
return cie._classInfo;
}
if (cie._classInfo.getDescribedClass() != null
&& cie._classInfo.getName().equals(clazz.getName())) {
if (osc == null) {
osc = ObjectStreamClass.lookupAny(clazz);
if (osc != null) {
suid = osc.getSerialVersionUID();
}
}
if (suid == cie._classInfo.getSUID()) {
return cie._classInfo;
}
}
cie = cie._next;
}
if (osc == null) {
osc = ObjectStreamClass.lookupAny(clazz);
}
if (osc != null) {
suid = osc.getSerialVersionUID();
}
_cacheMisses.incrementAndGet();
/**
* To update the tree, this class uses a unique SessionId and results in using a unique
* Transaction context unrelated to the application context. Therefore if an application does
* this:
*
* <pre>
* <code>
* txn.begin();
* value.put(new SomeClass());
* txn.rollback();
* txn.end();
* </code>
* </pre>
*
* the class SomeClass will be registered even though the enclosing transaction rolled back.
* This is important because other concurrent threads may have started using the handle for
* SomeClass. Therefore this class ensures that a non-nested transaction to insert the new
* ClassInfo into the system volume has committed before adding the handle to the hash table.
*/
synchronized (this) {
final SessionId saveSessionId = _persistit.getSessionId();
Exchange ex = null;
try {
_persistit.setSessionId(_sessionId);
ex = getExchange();
final Transaction txn = ex.getTransaction();
final ClassInfo ci;
final int handle;
txn.begin();
ex.clear().append(BY_NAME).append(clazz.getName()).append(suid).fetch();
final Value value = ex.getValue();
try {
if (value.isDefined()) {
value.setStreamMode(true);
handle = value.getInt();
final String storedName = value.getString();
final long storedSuid = value.getLong();
if (storedSuid != suid || !clazz.getName().equals(storedName)) {
throw new ConversionException(
"Class "
+ clazz.getName()
+ " persistent SUID="
+ storedSuid
+ " does not match current class SUID="
+ suid);
}
ci = new ClassInfo(clazz, suid, handle, osc);
} else {
//
// Store a new ClassInfo record
//
ex.clear().append(NEXT_ID).fetch();
handle = Math.max(_testIdFloor, value.isDefined() ? value.getInt() : HANDLE_BASE) + 1;
value.clear().put(handle);
ex.store();
value.clear();
value.setStreamMode(true);
value.put(handle);
value.put(clazz.getName());
value.put(suid);
ex.clear().append(BY_NAME).append(clazz.getName()).append(suid).store();
ex.clear().append(BY_HANDLE).append(handle).store();
ci = new ClassInfo(clazz, suid, handle, osc);
}
txn.commit();
hashClassInfo(ci);
return ci;
} finally {
txn.end();
}
} catch (final PersistitException pe) {
throw new ConversionException(pe);
} finally {
if (ex != null) {
releaseExchange(ex);
}
_persistit.setSessionId(saveSessionId);
}
}
}
