On Wed, Mar 10, 2010 at 6:48 AM, Daniel Baluta <daniel.bal...@gmail.com> wrote: > Hello, > > The following phrase taken from man 2 write manual page is confusing: > POSIX Â requires that a read(2) which can be proved to occur after a > write() has returned returns the new data. >
This parses properly. "a read(2) which can be proved to occur after a write() has returned" is a noun clause. > I think you should you some comas to make a clear statement. > POSIX Â requires that a read(2), which can be proved to occur after a > write() has returned, returns the new data. "a read(2)" is a noun clause. "which can be proved to occur after a write() has returned" is adverbial when separated by commas. Thus, in your suggested form, we would delete the stuff between commas because it's auxiliary; but this is incorrect, because it's a constraint. Perhaps the following: "POSIX requires a read(2) provably occuring after the return of a write() to return the new data." This is why more complex things are written in a very dry and structured manner... Given the assumptions: 1. That a write() has been performed; 2. That the write() performed in [1] has returned; 3. That a read() is performed; 4. That the read() performed in [3] had been performed at some time later than [2]; 5. That [4] is provable in the context of the program executing the read() The read() performed in [3] must return the new data acquired by the write() performed in [1]. Notice my wording in (5). If a program has not verified that a write() performed in another thread has returned correctly (by thread synchronization), then it may execute the read() before or after that write() has actually been performed (i.e. the program doesn't know any better). The OS of course would have an easier time making better assumptions, since it only has to check the real state of read/write requests internally. But whatever. This "communications" thing is complex. Words are hard to get down in a clear manner. > > thanks, > Daniel. > > -- > Ubuntu-devel-discuss mailing list > Ubuntu-devel-discuss@lists.ubuntu.com > Modify settings or unsubscribe at: > https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss > -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
