/// <summary>
/// get data of an image by specifying its image key
/// </summary>
/// <param name="key">key of image</param>
/// <returns>image data</returns>
public byte[] GetImageData(string key)
{
lock (imagelock) {
ImageCacheEntry entry;
if (!imagesbykey.TryGetValue(key, out entry))
{
entry = new ImageCacheEntry {
Image = context.Database.LoadEntities <ImageCacheItem>().Where(i => i.Key == key).Execute().FirstOrDefault(),
LifeTime = 300.0
};
images.Add(entry);
imagesbyid[entry.Image.ID] = entry;
imagesbykey[key] = entry;
}
RefreshImage(entry);
return(entry.Image.Data);
}
}
void OnTimerElapsed()
{
lock (imagelock) {
for (int i = images.Count - 1; i >= 0; --i)
{
ImageCacheEntry entry = images[i];
entry.LifeTime -= 1.0;
if (entry.LifeTime <= 0)
{
imagesbyid.Remove(entry.Image.ID);
if (!string.IsNullOrEmpty(entry.Image.Key))
{
imagesbykey.Remove(entry.Image.Key);
}
images.RemoveAt(i);
}
}
context.Database.Delete <ImageCacheItem>().Where(i => i.Expiration < DateTime.Now).Execute();
}
}
/// <summary>
/// get data of an image by specifying its image id
/// </summary>
/// <param name="imageid">id of image</param>
/// <returns>image data</returns>
public byte[] GetImageData(long imageid)
{
lock (imagelock) {
ImageCacheEntry entry;
if (!imagesbyid.TryGetValue(imageid, out entry))
{
entry = new ImageCacheEntry {
Image = context.Database.LoadEntities <ImageCacheItem>().Where(i => i.ID == imageid).Execute().FirstOrDefault(),
LifeTime = 300.0
};
images.Add(entry);
imagesbyid[imageid] = entry;
if (!string.IsNullOrEmpty(entry.Image.Key))
{
imagesbykey[entry.Image.Key] = entry;
}
}
RefreshImage(entry);
return(entry.Image.Data);
}
}
void RefreshImage(ImageCacheEntry entry)
{
if (DateTime.Now - entry.Image.LastUpdate < refreshTime)
{
return;
}
byte[] data;
try {
using (WebClient client = new WebClient()) {
data = client.DownloadData(entry.Image.URL);
}
}
catch (Exception e) {
Logger.Warning(this, $"Unable to refresh image '{entry.Image.URL}'", e.Message);
context.Database.Update <ImageCacheItem>().Set(i => i.LastUpdate == DateTime.Now).Where(i => i.ID == entry.Image.ID).Execute();
return;
}
entry.Image.Data = data;
context.Database.Update <ImageCacheItem>().Set(i => i.Data == data, i => i.LastUpdate == DateTime.Now).Where(i => i.ID == entry.Image.ID).Execute();
}
