public static Engine createSnapshotFor(Engine engine) {
if (engine.isReadOnly()) return engine;
if (engine instanceof TxEngine) return ((TxEngine) engine).snapshot();
if (engine instanceof EngineWrapper)
createSnapshotFor(((EngineWrapper) engine).getWrappedEngine());
throw new UnsupportedOperationException(
"Snapshots are not enabled, use DBMaker.snapshotEnable()");
}
/** constructs Engine using current settings */
public Engine makeEngine() {
final boolean readOnly = propsGetBool(Keys.readOnly);
final File file = props.containsKey(Keys.file) ? new File(props.getProperty(Keys.file)) : null;
final String volume = props.getProperty(Keys.volume);
final String store = props.getProperty(Keys.store);
if (readOnly && file == null)
throw new UnsupportedOperationException("Can not open in-memory DB in read-only mode.");
if (readOnly && !file.exists() && !Keys.store_append.equals(store)) {
throw new UnsupportedOperationException("Can not open non-existing file in read-only mode.");
}
if (propsGetLong(Keys.sizeLimit, 0) > 0 && Keys.store_append.equals(store))
throw new UnsupportedOperationException("Append-Only store does not support Size Limit");
extendArgumentCheck();
Engine engine;
if (!Keys.store_append.equals(store)) {
Volume.Factory folFac = extendStoreVolumeFactory();
engine =
propsGetBool(Keys.transactionDisable)
? extendStoreDirect(folFac)
: extendStoreWAL(folFac);
} else {
if (Keys.volume_heap.equals(volume) || Keys.volume_offheap.equals(volume))
throw new UnsupportedOperationException(
"Append Storage format is not supported with in-memory dbs");
engine = extendStoreAppend();
}
engine = extendWrapStore(engine);
if (propsGetBool(Keys.asyncWrite) && !readOnly) {
engine = extendAsyncWriteEngine(engine);
}
final String cache = props.getProperty(Keys.cache, CC.DEFAULT_CACHE);
if (Keys.cache_disable.equals(cache)) {
// do not wrap engine in cache
} else if (Keys.cache_hashTable.equals(cache)) {
engine = extendCacheHashTable(engine);
} else if (Keys.cache_hardRef.equals(cache)) {
engine = extendCacheHardRef(engine);
} else if (Keys.cache_weakRef.equals(cache)) {
engine = extendCacheWeakRef(engine);
} else if (Keys.cache_softRef.equals(cache)) {
engine = extendCacheSoftRef(engine);
} else if (Keys.cache_lru.equals(cache)) {
engine = extendCacheLRU(engine);
} else {
throw new IllegalArgumentException("unknown cache type: " + cache);
}
engine = extendWrapCache(engine);
if (propsGetBool(Keys.snapshots)) engine = extendSnapshotEngine(engine);
engine = extendWrapSnapshotEngine(engine);
if (readOnly) engine = new ReadOnlyEngine(engine);
if (propsGetBool(Keys.closeOnJvmShutdown)) {
engine = new EngineWrapper.CloseOnJVMShutdown(engine);
}
// try to read one record from DB, to make sure encryption and compression are correctly set.
Fun.Tuple2<Integer, byte[]> check = null;
try {
check = (Fun.Tuple2<Integer, byte[]>) engine.get(Engine.CHECK_RECORD, Serializer.BASIC);
if (check != null) {
if (check.a.intValue() != Arrays.hashCode(check.b))
throw new RuntimeException("invalid checksum");
}
} catch (Throwable e) {
throw new IllegalArgumentException(
"Error while opening store. Make sure you have right password, compression or encryption is well configured.",
e);
}
if (check == null && !engine.isReadOnly()) {
// new db, so insert testing record
byte[] b = new byte[127];
new Random().nextBytes(b);
check = Fun.t2(Arrays.hashCode(b), b);
engine.update(Engine.CHECK_RECORD, check, Serializer.BASIC);
engine.commit();
}
return engine;
}