public async Task <OcrResult> QueueForeground(IOcrEngine ocrEngine, ScannedImage.Snapshot snapshot, string tempImageFilePath, OcrParams ocrParams, CancellationToken cancelToken)
{
OcrRequest req;
lock (this)
{
ocrEngine = ocrEngine ?? ocrManager.ActiveEngine ?? throw new ArgumentException("No OCR engine available");
ocrParams = ocrParams ?? ocrManager.DefaultParams;
var reqParams = new OcrRequestParams(snapshot, ocrEngine, ocrParams);
req = requestCache.GetOrSet(reqParams, () => new OcrRequest(reqParams));
// Fast path for cached results
if (req.Result != null)
{
SafeDelete(tempImageFilePath);
return(req.Result);
}
// Manage ownership of the provided temp file
if (req.TempImageFilePath == null)
{
req.TempImageFilePath = tempImageFilePath;
}
else
{
SafeDelete(tempImageFilePath);
}
// Increment the reference count
req.ForegroundCount += 1;
queueWaitHandle.Release();
}
// If no worker threads are running, start them
EnsureWorkerThreads();
// Wait for completion or cancellation
await Task.Factory.StartNew(() =>
{
try
{
WaitHandle.WaitAny(new[] { req.WaitHandle, cancelToken.WaitHandle });
}
catch (Exception e)
{
Log.ErrorException("Error in OcrRequestQueue.QueueForeground response task", e);
}
}, TaskCreationOptions.LongRunning);
lock (this)
{
// Decrement the reference count
req.ForegroundCount -= 1;
// If all requestors have cancelled and there's no result to cache, delete the request
DestroyRequest(req);
}
// If no requests are pending, stop the worker threads
EnsureWorkerThreads();
// May return null if cancelled
return(req.Result);
}
public bool HasCachedResult(IOcrEngine ocrEngine, ScannedImage.Snapshot snapshot, OcrParams ocrParams)
{
ocrEngine = ocrEngine ?? ocrManager.ActiveEngine ?? throw new ArgumentException("No OCR engine available");
ocrParams = ocrParams ?? ocrManager.DefaultParams;
var reqParams = new OcrRequestParams(snapshot, ocrEngine, ocrParams);
lock (this)
{
return(requestCache.ContainsKey(reqParams) && requestCache[reqParams].Result != null);
}
}
public void QueueBackground(ScannedImage.Snapshot snapshot, string tempImageFilePath, OcrParams ocrParams)
{
OcrRequest req;
CancellationTokenSource cts = new CancellationTokenSource();
lock (this)
{
var ocrEngine = ocrManager.ActiveEngine;
if (ocrEngine == null)
{
return;
}
ocrParams = ocrParams ?? ocrManager.DefaultParams;
var reqParams = new OcrRequestParams(snapshot, ocrEngine, ocrParams);
req = requestCache.GetOrSet(reqParams, () => new OcrRequest(reqParams));
// Fast path for cached results
if (req.Result != null)
{
return;
}
// Manage ownership of the provided temp file
if (req.TempImageFilePath == null)
{
req.TempImageFilePath = tempImageFilePath;
}
else
{
SafeDelete(tempImageFilePath);
}
// Increment the reference count
req.BackgroundCount += 1;
snapshot.Source.ThumbnailInvalidated += (sender, args) => cts.Cancel();
snapshot.Source.FullyDisposed += (sender, args) => cts.Cancel();
queueWaitHandle.Release();
}
// If no worker threads are running, start them
EnsureWorkerThreads();
var op = StartingOne();
Task.Factory.StartNew(() =>
{
try
{
WaitHandle.WaitAny(new[] { req.WaitHandle, cts.Token.WaitHandle, op.CancelToken.WaitHandle });
lock (this)
{
// Decrement the reference count
req.BackgroundCount -= 1;
// If all requestors have cancelled and there's no result to cache, delete the request
DestroyRequest(req);
}
FinishedOne();
// If no requests are pending, stop the worker threads
EnsureWorkerThreads();
}
catch (Exception e)
{
Log.ErrorException("Error in OcrRequestQueue.QueueBackground response task", e);
}
}, TaskCreationOptions.LongRunning);
}
public OcrRequest(OcrRequestParams reqParams)
{
Params = reqParams;
}
