public JournalEntry(JournalFile file, string resourceName, long position, long pageNumber)
{
File = file;
ResourceName = resourceName;
Position = position;
PageNumber = pageNumber;
}
public void SetCheckPoint(bool flushJournals)
{
// No Logging
if (!EnableLogging)
{
return;
}
// Return if Read-only
if (ReadOnly)
{
return;
}
bool persisting;
lock (topJournalLock) {
JournalFile topJ = TopJournal;
// When the journal exceeds a threshold then we cycle the top journal
if (flushJournals || topJ.Length > (256 * 1024))
{
// Cycle to the next journal file
NewTopJournalFile();
// Add this to the archives
journalArchives.Add(topJ);
}
persisting = journalArchives.Count > 0;
topJ.SetCheckPoint();
}
if (persisting)
{
// Notifies the background thread that there is something to persist.
// This will block until there are at most 10 journal files open.
journalingThread.PersistArchives(10);
}
}
public JournalSummary(JournalFile journalFile)
{
JournalFile = journalFile;
Resources = new List <string>();
}
public override void Read(long pageNumber, byte[] buffer, int offset)
{
lock (journalMap) {
if (!dataOpen)
{
throw new IOException("Assertion failed: Data file is not open.");
}
}
// The list of all journal entries on this page number
var allJournalEntries = new List <JournalEntry>(4);
try {
// The map index.
lock (journalMap) {
int i = ((int)(pageNumber & 0x0FFFFFFF) % journalMap.Length);
var entry = journalMap[i];
JournalEntry prev = null;
while (entry != null)
{
bool deletedHash = false;
JournalFile file = entry.File;
// Note that once we have a reference the journal file can not be
// deleted.
file.Reference();
// If the file is closed (or deleted)
if (file.IsDeleted)
{
deletedHash = true;
// Deleted so remove the reference to the journal
file.Dereference();
// Remove the journal entry from the chain.
if (prev == null)
{
journalMap[i] = entry.Next;
}
else
{
prev.Next = entry.Next;
}
}
// Else if not closed then is this entry the page number?
else if (entry.PageNumber == pageNumber)
{
allJournalEntries.Add(entry);
}
else
{
// Not the page we are looking for so remove the reference to the
// file.
file.Dereference();
}
// Only move prev is we have NOT deleted a hash entry
if (!deletedHash)
{
prev = entry;
}
entry = entry.Next;
}
}
// Read any data from the underlying file
if (thereIsBackingData)
{
long pagePosition = pageNumber * JournaledSystem.PageSize;
// First Read the page from the underlying store.
Data.Read(pagePosition, buffer, offset, JournaledSystem.PageSize);
}
else
{
// Clear the buffer
for (int i = offset; i < (JournaledSystem.PageSize + offset); ++i)
{
buffer[i] = 0;
}
}
// Rebuild from the journal file(s)
int sz = allJournalEntries.Count;
for (int i = 0; i < sz; ++i)
{
var entry = allJournalEntries[i];
var file = entry.File;
long position = entry.Position;
lock (file) {
file.BuildPage(pageNumber, position, buffer, offset);
}
}
} finally {
// Make sure we remove the reference for all the journal files.
int sz = allJournalEntries.Count;
for (int i = 0; i < sz; ++i)
{
var entry = allJournalEntries[i];
JournalFile file = entry.File;
file.Dereference();
}
}
}
public override void Write(long pageNumber, byte[] buffer, int offset, int count)
{
lock (journalMap) {
if (!dataOpen)
{
throw new IOException("Assertion failed: Data file is not open.");
}
// Make this modification input the log
var journal = JournaledSystem.LogPageModification(Name, pageNumber, buffer, offset, count);
// This adds the modification to the END of the hash list. This means
// when we reconstruct the page the journals will always be input the
// correct order - from oldest to newest.
// The map index.
int i = ((int)(pageNumber & 0x0FFFFFFF) % journalMap.Length);
var entry = journalMap[i];
// Make sure this entry is added to the END
if (entry == null)
{
// Add at the head if no first entry
journalMap[i] = journal;
journal.Next = null;
}
else
{
// Otherwise search to the end
// The number of journal entries input the linked list
int journalEntryCount = 0;
while (entry.Next != null)
{
entry = entry.Next;
++journalEntryCount;
}
// and add to the end
entry.Next = journal;
journal.Next = null;
// If there are over 35 journal entries, scan and remove all entries
// on journals that have persisted
if (journalEntryCount > 35)
{
entry = journalMap[i];
JournalEntry prev = null;
while (entry != null)
{
bool deletedHash = false;
JournalFile file = entry.File;
// Note that once we have a reference the journal file can not be
// deleted.
file.Reference();
// If the file is closed (or deleted)
if (file.IsDeleted)
{
deletedHash = true;
// Deleted so remove the reference to the journal
file.Dereference();
// Remove the journal entry from the chain.
if (prev == null)
{
journalMap[i] = entry.Next;
}
else
{
prev.Next = entry.Next;
}
}
// Remove the reference
file.Dereference();
// Only move prev is we have NOT deleted a hash entry
if (!deletedHash)
{
prev = entry;
}
entry = entry.Next;
}
}
}
}
}
public JournalSummary(JournalFile journalFile)
{
JournalFile = journalFile;
Resources = new List<string>();
}
private void Execute()
{
bool localFinished = false;
while (!localFinished)
{
List <JournalFile> toProcess = null;
lock (system.topJournalLock) {
if (system.journalArchives.Count > 0)
{
toProcess = new List <JournalFile>();
toProcess.AddRange(system.journalArchives);
}
}
if (toProcess == null)
{
// Nothing to process so wait
lock (this) {
if (!finished)
{
#if PCL
try {
Monitor.Wait(this);
} catch (OperationCanceledException) {
}
#else
try {
Monitor.Wait(this);
} catch (ThreadInterruptedException) { /* ignore */ }
#endif
}
}
}
else if (toProcess.Count > 0)
{
// Something to process, so go ahead and process the journals,
int sz = toProcess.Count;
// For all journals
for (int i = 0; i < sz; ++i)
{
// Pick the lowest journal to persist
JournalFile jf = toProcess[i];
try {
// Persist the journal
jf.Persist(8, jf.Length);
// Close and then delete the journal file
jf.CloseAndDelete();
} catch (IOException e) {
system.Context.OnError(String.Format("Error persisting journal '{0}", jf), e);
// If there is an error persisting the best thing to do is
// finish
lock (this) {
finished = true;
}
}
}
}
lock (this) {
localFinished = finished;
// Remove the journals that we have just persisted.
if (toProcess != null)
{
lock (system.topJournalLock) {
int sz = toProcess.Count;
for (int i = 0; i < sz; ++i)
{
system.journalArchives.RemoveAt(0);
}
}
}
// Notify any threads waiting
Monitor.PulseAll(this);
}
}
lock (this) {
actually_finished = true;
Monitor.PulseAll(this);
}
}
private void RollForwardRecover()
{
// The list of all journal files,
var journalFilesList = new List <JournalSummary>();
// Scan the journal path for any journal files.
for (int i = 10; i < 74; ++i)
{
string journalFn = GetJournalFileName(i);
string f = FileSystem.CombinePath(JournalPath, journalFn);
// If the journal exists, create a summary of the journal
if (FileSystem.FileExists(f))
{
if (ReadOnly)
{
throw new IOException(
"Journal file " + f + " exists for a read-only session. " +
"There may not be any pending journals for a Read-only session.");
}
var jf = new JournalFile(this, FileSystem, f, ReadOnly);
// Open the journal file for recovery. This will set various
// information about the journal such as the last check point and the
// id of the journal file.
JournalSummary summary = jf.OpenForRecovery();
// If the journal can be recovered from.
if (summary.CanBeRecovered)
{
Context.OnInformation(String.Format("Journal '{0}' found: can be recovered", jf));
journalFilesList.Add(summary);
}
else
{
Context.OnInformation(String.Format("Deleting journal '{0}': nothing to recover", jf));
// Otherwise close and delete it
jf.CloseAndDelete();
}
}
}
// Sort the journal file list from oldest to newest. The oldest journals
// are recovered first.
journalFilesList.Sort(new JournalSummaryComparer());
long lastJournalNumber = -1;
// Persist the journals
for (int i = 0; i < journalFilesList.Count; ++i)
{
var summary = journalFilesList[i];
// Check the resources for this summary
var resList = summary.Resources;
foreach (string resourceName in resList)
{
// This puts the resource into the hash map.
CreateResource(resourceName);
}
// Assert that we are recovering the journals input the correct order
JournalFile jf = summary.JournalFile;
if (jf.JournalNumber < lastJournalNumber)
{
throw new InvalidOperationException("Assertion failed, sort failed.");
}
lastJournalNumber = jf.JournalNumber;
Context.OnInformation(String.Format("Recovering '{0}' (8 .. {1})", jf, summary.LastCheckPoint));
jf.Persist(8, summary.LastCheckPoint);
// Then close and delete.
jf.CloseAndDelete();
// Check the resources for this summary and close them
foreach (var resourceName in resList)
{
var resource = (ResourceBase)CreateResource(resourceName);
// When we finished, make sure the resource is closed again
// Close the resource
resource.PersistClose();
// Post recover notification
resource.OnPostRecover();
}
}
}
