private long readHeader(int id) throws IOException {
long header = p_alloc(MINIMUM_PAGE_SIZE);
try {
try {
mPageArray.readPage(id, header, 0, MINIMUM_PAGE_SIZE);
} catch (EOFException e) {
throw new CorruptDatabaseException("File is smaller than expected");
}
long magic = p_longGetLE(header, I_MAGIC_NUMBER);
if (magic != MAGIC_NUMBER) {
throw new CorruptDatabaseException("Wrong magic number: " + magic);
}
int checksum = p_intGetLE(header, I_CHECKSUM);
int newChecksum = setHeaderChecksum(header);
if (newChecksum != checksum) {
throw new CorruptDatabaseException(
"Header checksum mismatch: " + newChecksum + " != " + checksum);
}
return header;
} catch (Throwable e) {
p_delete(header);
throw e;
}
}
/** @see _SnapshotPageArray#beginSnapshot */
Snapshot beginSnapshot(_LocalDatabase db) throws IOException {
mHeaderLatch.acquireShared();
try {
long pageCount, redoPos;
long header = p_alloc(MINIMUM_PAGE_SIZE);
try {
mPageArray.readPage(mCommitNumber & 1, header, 0, MINIMUM_PAGE_SIZE);
pageCount = _PageManager.readTotalPageCount(header, I_MANAGER_HEADER);
redoPos = _LocalDatabase.readRedoPosition(header, I_EXTRA_DATA);
} finally {
p_delete(header);
}
return mPageArray.beginSnapshot(db, pageCount, redoPos);
} finally {
mHeaderLatch.releaseShared();
}
}
@Override
public void readPage(long id, long page) throws IOException {
try {
mPageArray.readPage(id, page, 0, pageSize());
} catch (Throwable e) {
throw closeOnFailure(e);
}
}
private void readPartial(long index, int start, byte[] buf, int offset, int length)
throws IOException {
long page = p_alloc(start + length);
try {
mPageArray.readPage(index, page, 0, start + length);
p_copyToArray(page, start, buf, offset, length);
} finally {
p_delete(page);
}
}
@Override
public void deletePage(long id) throws IOException {
checkId(id);
CommitLock.Shared shared = mCommitLock.acquireShared();
try {
mPageManager.deletePage(id);
} catch (IOException e) {
throw e;
} catch (Throwable e) {
throw closeOnFailure(e);
} finally {
shared.release();
}
mPageArray.uncachePage(id);
}
@Override
public void close(Throwable cause) throws IOException {
if (mPageArray != null) {
mPageArray.close(cause);
}
}
@Override
public long copyPage(long srcId, long dstId) throws IOException {
return mPageArray.copyPage(srcId, dstId);
}
@Override
public long dirtyPage(long id) throws IOException {
return mPageArray.dirtyPage(id);
}
@Override
public long directPagePointer(long id) throws IOException {
return mPageArray.directPagePointer(id);
}
@Override
public void uncachePage(long id) throws IOException {
mPageArray.uncachePage(id);
}
@Override
public void cachePage(long id, long page) throws IOException {
mPageArray.cachePage(id, page);
}
@Override
public long evictPage(long id, long page) throws IOException {
checkId(id);
return mPageArray.evictPage(id, page);
}
@Override
public void writePage(long id, long page) throws IOException {
checkId(id);
mPageArray.writePage(id, page, 0);
}
@Override
public long pageCount() throws IOException {
return mPageArray.getPageCount();
}
@Override
public int pageSize() {
return mPageArray.pageSize();
}
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);
}
}