FileInfo.Length不能始终为我提供正确的文件大小

Question

I am facing a very strange issue with FileInfo and the Length property. I am writing a server that responds to calls to send files (mainly images) to the clients. I want to send the file size to the client before I send the actual file. I am using FileInfo to find the file size but strangely it does not give me the correct size every time. Put differently, for the same file I receive different sizes, sometimes less than the actual size and sometimes correct (but never more than the actual size). What makes the problem even more strange, if I copy the same code to a new project (not a server, just a test project) it works fine and gives correct answers. The server use threads so multiple clients can connect (the test project doesn't) but I don't think that this has anything to do with FileInfo . Here is my code:

String fullFilePath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + "\\" + imageName;
FileInfo file1 = new FileInfo(fullFilePath);
Console.Writeline("File Size: {0}", file1.Length);

Very basic code! My images are small in the range of 4 to 10 Kbytes only. Am I doing something wrong? Any suggestions?

Answer 1

I got it after all! The problem was not in the FileInfo class, the problem was a concept problem in my client server communication. The images originally are not on the server, they come from another clients. What was happening is that a client was sending an image to the server, and a request to get this image was reaching the server from another client but before the server actually finished saving the image on the disk. Therefore the FileInfo was getting the Length of the currently saved bytes and not the total bytes of the file.

The solution was as follows: when a file was sent to the server, allow some time (for example 1 second) for the server to finish the saving process before this file can become ready to be downloaded by other clients.