/**
* Flush a specified ledger
*
* @param ledger Ledger Id
* @throws IOException
*/
private void flushSpecificLedger(long ledger) throws IOException {
LinkedList<Long> firstEntryList = pageMapAndList.getFirstEntryListToBeFlushed(ledger);
// flush ledger index file header if necessary
indexPersistenceManager.flushLedgerHeader(ledger);
if (null == firstEntryList || firstEntryList.size() == 0) {
LOG.debug("Nothing to flush for ledger {}.", ledger);
// nothing to do
return;
}
// Now flush all the pages of a ledger
List<LedgerEntryPage> entries = new ArrayList<LedgerEntryPage>(firstEntryList.size());
try {
for (Long firstEntry : firstEntryList) {
LedgerEntryPage lep = getLedgerEntryPage(ledger, firstEntry, true);
if (lep != null) {
entries.add(lep);
}
}
indexPersistenceManager.flushLedgerEntries(ledger, entries);
} finally {
for (LedgerEntryPage lep : entries) {
lep.releasePage();
}
}
}
/**
* Grab ledger entry page whose first entry is <code>pageEntry</code>.
*
* <p>If the page doesn't existed before, we allocate a memory page. Otherwise, we grab a clean
* page and read it from disk.
*
* @param ledger Ledger Id
* @param pageEntry Start entry of this entry page.
*/
private LedgerEntryPage grabLedgerEntryPage(long ledger, long pageEntry) throws IOException {
LedgerEntryPage lep = grabCleanPage(ledger, pageEntry);
try {
// should get the up to date page from the persistence manager
// before we put it into table otherwise we would put
// an empty page in it
indexPersistenceManager.updatePage(lep);
LedgerEntryPage oldLep;
if (lep != (oldLep = pageMapAndList.putPage(lep))) {
lep.releasePage();
// Decrement the page count because we couldn't put this lep in the page cache.
pageCount.decrementAndGet();
// Increment the use count of the old lep because this is unexpected
oldLep.usePage();
lep = oldLep;
}
} catch (IOException ie) {
// if we grab a clean page, but failed to update the page
// we are exhausting the count of ledger entry pages.
// since this page will be never used, so we need to decrement
// page count of ledger cache.
lep.releasePage();
pageCount.decrementAndGet();
throw ie;
}
return lep;
}