/** @param header array length is full page */
private void commitHeader(final long header, final int commitNumber) throws IOException {
final PageArray array = mPageArray;
p_longPutLE(header, I_MAGIC_NUMBER, MAGIC_NUMBER);
p_intPutLE(header, I_PAGE_SIZE, array.pageSize());
p_intPutLE(header, I_COMMIT_NUMBER, commitNumber);
// Durably write the new page store header before returning
// from this method, to ensure that the manager doesn't start
// returning uncommitted pages. This would prevent rollback
// from working because the old pages would get overwritten.
setHeaderChecksum(header);
// Write multiple header copies in the page, in case special recovery is required.
int dupCount = pageSize() / MINIMUM_PAGE_SIZE;
for (int i = 1; i < dupCount; i++) {
p_copy(header, 0, header, i * MINIMUM_PAGE_SIZE, MINIMUM_PAGE_SIZE);
}
// Ensure all writes are flushed before flushing the header. There's
// otherwise no ordering guarantees. Metadata should also be flushed
// first, because the header won't affect it.
array.sync(true);
mHeaderLatch.acquireExclusive();
try {
array.writePage(commitNumber & 1, header);
mCommitNumber = commitNumber;
} finally {
mHeaderLatch.releaseExclusive();
}
// Final sync to ensure the header is durable.
array.syncPage(commitNumber & 1);
}
private _DurablePageDb(
final PageArray rawArray, final PageCache cache, final Crypto crypto, final boolean destroy)
throws IOException, WrongPageSize {
mCrypto = crypto;
PageArray array = crypto == null ? rawArray : new CryptoPageArray(rawArray, crypto);
mPageArray = new _SnapshotPageArray(array, rawArray, cache);
mHeaderLatch = new Latch();
try {
int pageSize = mPageArray.pageSize();
checkPageSize(pageSize);
if (destroy || mPageArray.isEmpty()) {
// Newly created file.
mPageManager = new _PageManager(mPageArray);
mCommitNumber = -1;
// Commit twice to ensure both headers have valid data.
long header = p_calloc(pageSize);
try {
mCommitLock.acquireExclusive();
try {
commit(false, header, null);
commit(false, header, null);
} finally {
mCommitLock.releaseExclusive();
}
} finally {
p_delete(header);
}
mPageArray.setPageCount(2);
} else {
// Opened an existing file.
// Previous header commit operation might have been interrupted before final
// header sync completed. Pages cannot be safely recycled without this.
mPageArray.sync(false);
long header0 = p_null();
long header1 = p_null();
try {
final long header;
final int commitNumber;
findHeader:
{
int pageSize0;
int commitNumber0, commitNumber1;
CorruptDatabaseException ex0;
try {
header0 = readHeader(0);
commitNumber0 = p_intGetLE(header0, I_COMMIT_NUMBER);
pageSize0 = p_intGetLE(header0, I_PAGE_SIZE);
ex0 = null;
} catch (CorruptDatabaseException e) {
header0 = p_null();
commitNumber0 = -1;
pageSize0 = pageSize;
ex0 = e;
}
if (pageSize0 != pageSize) {
throw new WrongPageSize(pageSize, pageSize0);
}
try {
header1 = readHeader(1);
commitNumber1 = p_intGetLE(header1, I_COMMIT_NUMBER);
} catch (CorruptDatabaseException e) {
if (ex0 != null) {
// File is completely unusable.
throw ex0;
}
header = header0;
commitNumber = commitNumber0;
break findHeader;
}
int pageSize1 = p_intGetLE(header1, I_PAGE_SIZE);
if (pageSize0 != pageSize1) {
throw new CorruptDatabaseException(
"Mismatched page sizes: " + pageSize0 + " != " + pageSize1);
}
if (header0 == p_null()) {
header = header1;
commitNumber = commitNumber1;
} else {
// Modulo comparison.
int diff = commitNumber1 - commitNumber0;
if (diff > 0) {
header = header1;
commitNumber = commitNumber1;
} else if (diff < 0) {
header = header0;
commitNumber = commitNumber0;
} else {
throw new CorruptDatabaseException(
"Both headers have same commit number: " + commitNumber0);
}
}
}
mHeaderLatch.acquireExclusive();
mCommitNumber = commitNumber;
mHeaderLatch.releaseExclusive();
mPageManager = new _PageManager(mPageArray, header, I_MANAGER_HEADER);
} finally {
p_delete(header0);
p_delete(header1);
}
}
} catch (WrongPageSize e) {
delete();
closeQuietly(null, this);
throw e;
} catch (Throwable e) {
delete();
throw closeOnFailure(e);
}
}