/**
* Reverses the operations detailed in the list of deltas on the given wavelet.
*
* @param wavelet {@link ObservableWaveletData} to apply operations to
* @param deltas the {@link WaveletDelta} containing the operations which we should revert on the
* given wavelet.
* @throws OperationException if the operations can not be rolled back.
*/
private static void rollback(ObservableWaveletData wavelet, List<TransformedWaveletDelta> deltas)
throws OperationException {
List<WaveletOperation> inverseOps = Lists.newArrayList();
// Go through everything in reverse order
for (int i = deltas.size() - 1; i >= 0; i--) {
TransformedWaveletDelta delta = deltas.get(i);
// Metadata such as the last modified ts will change due to the rollback
// of operations.
for (int j = delta.size() - 1; j >= 0; j--) {
WaveletOperation op = delta.get(j);
WaveletOperation inverseOp = WaveletOperationInverter.invert(op);
inverseOps.add(inverseOp);
}
}
long startVersion = wavelet.getVersion();
int opCount = 0;
for (WaveletOperation inverseOp : inverseOps) {
inverseOp.apply(wavelet);
opCount++;
}
if (wavelet.getVersion() != startVersion - opCount) {
throw new OperationException(
"Expected end version "
+ (startVersion - opCount)
+ " doesn't match the version of the wavelet "
+ wavelet.getVersion());
}
}
/**
* Apply a list of operations from a single delta to the wavelet container.
*
* @param ops to apply
*/
protected void applyWaveletOperations(List<WaveletOperation> ops)
throws OperationException, EmptyDeltaException {
if (ops.isEmpty()) {
LOG.warning("No operations to apply at version " + currentVersion);
throw new EmptyDeltaException();
}
WaveletOperation lastOp = null;
int opsApplied = 0;
try {
for (WaveletOperation op : ops) {
lastOp = op;
op.apply(waveletData);
opsApplied++;
}
} catch (OperationException e) {
LOG.warning(
"Only applied "
+ opsApplied
+ " of "
+ ops.size()
+ " operations at version "
+ currentVersion
+ ", rolling back, failed op was "
+ lastOp,
e);
// Deltas are atomic, so roll back all operations that were successful
rollbackWaveletOperations(ops.subList(0, opsApplied));
throw new OperationException("Failed to apply all operations, none were applied", e);
}
}
private TransformedWaveletDelta delta(WaveletOperation... ops) {
WaveletOperation last = ops[ops.length - 1];
WaveletOperationContext ctx = last.getContext();
return new TransformedWaveletDelta(
ctx.getCreator(), ctx.getHashedVersion(), ctx.getTimestamp(), Arrays.asList(ops));
}