On Feb 7, 2014, at 1:56 PM, Dmitri Gribenko <[email protected]> wrote:
> On Fri, Feb 7, 2014 at 9:54 PM, Argyrios Kyrtzidis <[email protected]> > wrote: >> On Feb 7, 2014, at 1:46 PM, Dmitri Gribenko <[email protected]> wrote: >> >>> On Fri, Feb 7, 2014 at 9:39 PM, Argyrios Kyrtzidis <[email protected]> >>> wrote: >>>> On Feb 7, 2014, at 12:47 PM, Dmitri Gribenko <[email protected]> wrote: >>>> I wanted to avoid the need to do the atomic-rename dance. >>>> >>>> What is you concern with it ? >>> >>> No real concerns, just a bit more code to write. >>> >>>> What is the >>>> potential for mtime confusion that you see? We could provide a >>>> function in libclang to get the current timestamp so that clients >>>> don't have to invent their own, potentially incorrect way to get it. >>>> >>>> >>>> I really want to reduce complexity here and potential for out-of-sync, >>>> because now you have >>>> >>>> >>>> 1) The builder needs to provide an increasing timestamp by getting clock >>>> time (or libclang call ?) >>>> 2) we will compare that clock time with the file system modification time >>>> which can come from any kind of underlying file system >>>> >>>> >>>> vs >>>> >>>> 1) The builder needs to provide an increasing timestamp >>>> >>>> >>>> I much prefer the latter simpler approach. >>> >>> I can see how clients can break any of these while implementing (1) -- >>> for example, by using the local time instead of UTC time, and having >>> the build happen when the DST adjustment is made. But (2) is just an >>> OS-level thing, it can not go wrong. >>> >>> Also, imagine that we have a good client build system and a bad client >>> build system. A good client uses correct timestamps, a bad client >>> uses timestamps + 1 billion. Then after the bad client creates a >>> module, the good client will never rebuild it, because its timestamps >>> will always be "in the past”. >> >> A bad client will always be a problem but this is the responsibility of the >> builder, if the builder timestamps are self-consistent we don’t need to >> worry about any time changes or adjustments or what have you, it will not >> even need to be time based, we just don’t care. > > A bad client will only create a problem for itself if clang uses > filesystem mtime on the timestamp file. Ok, I retract my objections but with the current approach we definitely need a libclang API to control what gets passed in with the option (and provide a convenient way to “get it right”), could you add that ? > > Dmitri > > -- > main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if > (j){printf("%d\n",i);}}} /*Dmitri Gribenko <[email protected]>*/
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