/// <summary>
/// Returns the elevation cache entry (first searches the local cache, then the azure cache and finally loads the file from blob storage if it was not cached).
/// </summary>
/// <param name="fileName">Name of the file that is being cached.</param>
/// <param name="isArcData">if set to <c>true</c> [is arc data].</param>
/// <returns>Returns the cache entry (null if no entry was found)</returns>
private ElevationCacheEntry GetElevationEntry(string fileName, bool isArcData)
{
ElevationCacheEntry entry = null;
// First check local cache
if (this.localCache.ContainsKey(fileName))
{
entry = this.localCache[fileName];
entry.RefreshCacheDetails();
return(entry);
}
if (this.azureCache != null)
{
// Not in local cache, so check azure cache
entry = this.azureCache.Get(fileName) as ElevationCacheEntry;
if (entry != null)
{
this.localCache[fileName] = entry;
entry.RefreshCacheDetails();
}
}
// Not in local or azure cache, so read from azure storage
this.Add(fileName, isArcData);
if (this.localCache.ContainsKey(fileName))
{
entry = this.localCache[fileName];
}
return(entry);
}
/// <summary>
/// Adds the specified file to the cache (in memory)
/// </summary>
/// <param name="filename">File to be cached in memory</param>
public void Add(string filename)
{
string logMethodName = "ElevationCache.Add (filename -> " + filename;
bool cacheSizeExceeded = false;
string dataDirectory = Utils.Configuration["dataDirectory"];
try
{
//// Check to see if the cache size has exceeded
cacheSizeExceeded = this.GetMemoryUsage() >= this.maxLocalCacheSize;
if (cacheSizeExceeded)
{
this.CleanupLocalCache();
}
byte[] fileContents = null;
// Insert file contents into the cache
if (!this.localCache.ContainsKey(filename))
{
try
{
fileContents = (byte[])this.TerrainDalc.LoadTerrainFile(filename, dataDirectory, this.cacheElementSize);
}
catch (Exception ex)
{
this.Logger.Log(TraceEventType.Critical, LoggingMessageId.PropagationTileNotFound, string.Format("Tile Not Found for filename -> {0}", filename));
this.Logger.Log(TraceEventType.Critical, LoggingMessageId.PropagationException, ex.ToString());
fileContents = new byte[this.cacheElementSize];
}
ElevationCacheEntry newEntry = new ElevationCacheEntry(fileContents);
this.localCache.Add(filename, newEntry);
// Also add to azure cache.
if (this.azureCache != null)
{
// Since we just read this value from blog storage, lets also put it in azure cache.
this.azureCache.Put(filename, newEntry);
}
}
}
catch (Exception ex)
{
// We've hit a tile in Canada. We don't care about such a tile
// We hit a tile that does not exist for any Country in the system.
this.Logger.Log(TraceEventType.Error, LoggingMessageId.ElevationGlobUnsupportedTileId, logMethodName);
this.Logger.Log(TraceEventType.Error, LoggingMessageId.ElevationGlobUnsupportedTileId, ex.ToString());
}
}
/// <summary>
/// Returns bytes at the specified indices
/// </summary>
/// <param name="fileName">File Name</param>
/// <returns>cache object</returns>
public object ReadCachedData(string fileName)
{
ElevationCacheEntry entry = this.GetElevationEntry(fileName);
return(entry.Data);
}
