MasterPage findLatestMasterPage() throws IOException {
MasterPage latest = null;
for (int i = 0; i < MASTERPAGE_SLOTS; i++) {
// Because of crypto IV, we cannot read in bulk...
int position = MASTERPAGE_HEADER_SIZE + (i * MASTERPAGE_SLOT_SIZE);
ByteBuffer buffer =
Futures.get(readDirect(position, MASTERPAGE_SLOT_SIZE), IOException.class);
MasterPage masterPage = new MasterPage(buffer, 0);
if (!masterPage.isValid()) {
log.warn("Found corrupted master page slot {}", i);
continue;
}
if (latest == null) {
latest = masterPage;
} else if (latest.getTransactionId() < masterPage.getTransactionId()) {
latest = masterPage;
}
}
if (latest == null) {
throw new IOException("All master pages corrupted");
}
return latest;
}
ListenableFuture<Void> writeMasterPage(TransactionPage transactionPage, int transactionPageId) {
long transactionId = transactionPage.getTransactionId();
int newRootPage = transactionPage.getRootPageId();
int slot = (int) (transactionId % MASTERPAGE_SLOTS);
{
int position = MASTERPAGE_HEADER_SIZE + (slot * MASTERPAGE_SLOT_SIZE);
ByteBuffer mmap = ByteBuffer.allocate(MASTERPAGE_SLOT_SIZE);
assert mmap.position() == 0;
MasterPage.create(mmap, newRootPage, transactionPageId, transactionId);
mmap.position(MASTERPAGE_SLOT_SIZE);
mmap.flip();
assert mmap.remaining() == MASTERPAGE_SLOT_SIZE;
return writeDirect(position, mmap);
}
}
public ByteSource asByteSource(ReadOnlyTransaction txn) throws IOException {
ByteBuffer snapshotHeader = ByteBuffer.allocate(HEADER_SIZE);
{
ByteBuffer header = buildHeader();
assert header.remaining() == MASTERPAGE_HEADER_SIZE;
snapshotHeader.put(header);
}
// We build a master header with just the current snapshot transaction
for (int i = 0; i < MASTERPAGE_SLOTS; i++) {
int position = MASTERPAGE_HEADER_SIZE + (i * MASTERPAGE_SLOT_SIZE);
ByteBuffer mmap = ByteBuffer.allocate(MASTERPAGE_SLOT_SIZE);
assert mmap.position() == 0;
int rootPage = txn.rootPageId;
int transactionPage = txn.transactionPageId;
long transactionId = txn.snapshotTransactionId;
MasterPage.create(mmap, rootPage, transactionPage, transactionId);
mmap.position(MASTERPAGE_SLOT_SIZE);
mmap.flip();
assert mmap.remaining() == MASTERPAGE_SLOT_SIZE;
snapshotHeader.position(position);
snapshotHeader.put(mmap);
}
snapshotHeader.position(0);
ByteSource dataByteSource = asByteSource0();
dataByteSource = dataByteSource.slice(HEADER_SIZE, Long.MAX_VALUE);
return ByteSource.concat(new ByteBufferByteSource(snapshotHeader), dataByteSource);
}
