internal static ElementCacher RenewCache(ElementCacher oldCache)
{
lock (_clientCacheLock)
{
// If another thread has already updated the cache, we don't need to renew.
if (_currentCache != oldCache)
{
return(_currentCache);
}
// The size of the new cache.
int newCacheSize;
// Whether to copy the contents of the old cache into the new cache.
bool copyOldCache = false;
if (oldCache == null)
{
newCacheSize = FontCacheConstants.InitialLocalCacheSize;
}
else
{
newCacheSize = oldCache.MaxCacheSize * FontCacheConstants.CacheGrowthFactor;
if (newCacheSize > FontCacheConstants.MaximumLocalCacheSize)
{
newCacheSize = FontCacheConstants.MaximumLocalCacheSize;
}
else
{
copyOldCache = true;
}
}
// Current client cache either doesn't exist or it is obsolete,
// create a new one.
FileMapping m = new FileMapping();
m.Create(null, newCacheSize);
ElementCacher c = new ElementCacher(m, true, false);
if (copyOldCache)
{
// Copy the bits from the old cache.
Debug.Assert(newCacheSize > oldCache.CurrentSize);
c.InitFromPreviousCache(oldCache, newCacheSize);
}
// Flush the cache before exposing it, so that clients have a consistent view of it
Thread.MemoryBarrier();
_currentCache = c;
if (oldCache != null)
{
oldCache.MarkObsolete();
}
return(c);
}
}
// Disable Presharp warning about Dispose() not being called on the disposable FileMapping object.
// This is by design, because lifetime of m extends this function - the pointer is passed to ElementCacher ctor.
#pragma warning disable 6518
private static ElementCacher OpenServerCache(string serverSectionName)
{
// Disable Presharp warning about empty catch body.
// This is by design, as we should continue even in case of server connection failures.
#pragma warning disable 6502
try
{
// open cache
FileMapping m = new FileMapping();
m.OpenSection(serverSectionName);
ElementCacher c = new ElementCacher(m, false, true);
if (c.VersionUpToDate())
{
_serverCache = c;
return(c);
}
}
// This can be thrown when for some reason we cannot connect to the server.
catch (IOException)
{
}
return(null);
#pragma warning restore 6502
}
#pragma warning restore 6518
internal static void SaveNativeCache(ElementCacher c, IList <ElementCacher> nativeCaches)
{
int count = nativeCaches.Count;
if (count > 0 && c == nativeCaches[count - 1])
{
return; // it's already stored, so don't bother
}
nativeCaches.Add(c);
}
internal void InitFromPreviousCache(ElementCacher oldCache, int newCacheSize)
{
// We need to lock the old cache to make sure it's CurrentSize is not updated in the middle of the copy.
lock (oldCache.Lock)
{
InitFromCacheImage(oldCache.Mapping);
// Reset max cache size to the new size, because InitFromCacheImage overwrote it.
MaxCacheSize = newCacheSize;
}
}
internal static ElementCacher GetCurrentCache()
{
ElementCacher c = _currentCache;
if (c == null || c.IsObsolete())
{
c = RenewCache(c);
}
Debug.Assert(c != null);
return(c);
}
internal static ElementCacher GetServerCache()
{
// the current cache is up to date
if (_serverCache != null && !_serverCache.IsObsolete())
{
return(_serverCache);
}
// we know that connecting to the service will likely fail
if (!_tryToConnect)
{
return(_serverCache);
}
lock (_sharedCacheLock)
{
// repeat the checks from above within the lock
if (_serverCache != null && !_serverCache.IsObsolete())
{
return(_serverCache);
}
if (!_tryToConnect)
{
return(_serverCache);
}
if (_fc == null)
{
_fc = FontCacheConfig.Current;
_ipcMngr = new IPCCacheManager(_fc);
}
int errorCode = 0;
string serverSectionName = null;
if (_serverCache != null)
{
// Server port is open, but the cache is obsolete. Get a new section name.
Debug.Assert(_serverCache.IsObsolete());
Debug.Assert(_ipcMngr.IsConnected);
Debug.WriteLine("Retrieving cache name from server");
//Ignore error code, just let serverSectionName be null if error.
serverSectionName = _ipcMngr.GetServerSectionName(_fc.SecondConnectTimeout, out errorCode);
}
else
{
//Connect to the server and get the server cache
int[] timeouts = { _fc.FirstConnectTimeout, _fc.SecondConnectTimeout };
for (int i = 0; ; i++)
{
//If we had an old connection lying around close it and get rid of it
if (_ipcMngr.IsConnected)
{
_ipcMngr.CloseConnection();
}
//Get the server name. If we're not connected, connect.
serverSectionName = _ipcMngr.GetServerSectionName(timeouts[i], out errorCode);
//If we succeeded, we can stop here
if (serverSectionName != null)
{
break;//success
}
if ((i + 1) >= timeouts.Length)
{
break;//all attempts exhausted - give up
}
//If we failed, it could be because the font cache service isn't running,
//so try to start it now. Don't waste time with this if we fail for another reason.
if (errorCode == _ipcMngr.ServerNotFoundErrorCode)
{
if (_fc.RestartServiceOnError)
{
if (!ServiceOps.StartServiceWithTimeout(BuildInfo.FontCacheServiceName, _fc.ServerStartTimeout))
{
//could not start service - give up
break;
}
}
else
{
break;//restart service option not set
}
}
else
{
break;//no point in continuing
}
}
}
if (serverSectionName == null)
{
// keep using the old cache if the new name can't be obtained (or null if there is no old cache)
_ipcMngr.CloseConnection();
_tryToConnect = false;
return(_serverCache);
}
//Attempt to open the cache. Update _serverCache if successful,
//but keep using the old cache if there is an error.
ElementCacher c = OpenServerCache(serverSectionName);
if (c != null)
{
_serverCache = c;
}
else
{
// low memory conditions, don't attempt to connect, but keep using the old cache
_tryToConnect = false;
}
return(_serverCache);
}
}
