Re: Need design advice
"Ashutosh" wrote:
If I use Mutex for accessing the file, won't it be to many calls
to open & close the files as all the applications will be
continuously writing to the log. Also, this will slow down all
the application which are writing the log.
It is up to you to decide. You can open a file just once - at the
beginning of a process and then just to synchronize write access
between processes. You will need to flush file buffers, though.
So, basically htis approach is not much different from opening and
closing a file on each write.
You may do something more clever. You can store current file
position in a shared section of the logging DLL and advance it on
each write request. You will need to syncronize the access to the
file position between callers. Then each write request will
receive its own block within the file and wil be able to write
into it without clashes with other writers. For example:
Open - open file
R X - request X bytes
W X1-X2 - write from the offset X1 to X2
P - current file pointer
Process 1 Process 2 File position
1. Open P = 0
2. R 10 Open P += 10
3. R 15 P += 15
4. W 10-25
5. W 0-10
6. ...
So, the only part that requires a mutex is the shared file
pointer. And each process can write to the file without waiting
for others.
HTH
Alex