Hi all,
How atomic are read and write?
Background:
I want a queue implemented between different *threads*. At the moment, there are several threads that need to send data, and only one thread that retrieves the data from the queue. The most obvious answer seemed to be "use a pipe".
Here's the schema I was thinking of. Each client (which sends data on the queue) makes a copy (using "new") of the data, and then sends the pointer's address on the pipe using "write". The server does repeated "read"s of 4 bytes, uses the object, and then releases the memory.
The big question is - do I need to introduce a mutex into this mess? Is there a chance that the 4 byte "write" will not be performed in an atomic manner (i.e. - two "write"s will have their data mingled)?
Part II of the question has to do with more than one server. If there is any chance at all that read will not return all 4 bytes in one call, it's obvious that I can no longer guarantee the data integrity, even if "read" itself is atomic. My question is - how likely is it that such a thing will happen? Is there a chance that a series of four bytes "write" operations on a pipe will be split upon "read"?
Many thanks,
Shachar
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