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* ditch the priority inheritance locks; use malloc's version of lockRich Felker2012-04-241-2/+2
| | | | | | | | | | | | | | | | | | | i did some testing trying to switch malloc to use the new internal lock with priority inheritance, and my malloc contention test got 20-100 times slower. if priority inheritance futexes are this slow, it's simply too high a price to pay for avoiding priority inversion. maybe we can consider them somewhere down the road once the kernel folks get their act together on this (and perferably don't link it to glibc's inefficient lock API)... as such, i've switch __lock to use malloc's implementation of lightweight locks, and updated all the users of the code to use an array with a waiter count for their locks. this should give optimal performance in the vast majority of cases, and it's simple. malloc is still using its own internal copy of the lock code because it seems to yield measurably better performance with -O3 when it's inlined (20% or more difference in the contention stress test).
* new scanf implementation and corresponding integer parser/converterRich Felker2012-04-161-0/+2
| | | | | | | | | | | | | | | advantages over the old code: - correct results for floating point (old code was bogus) - wide/regular scanf separated so scanf does not pull in wide code - well-defined behavior on integers that overflow dest type - support for %[a-b] ranges with %[ (impl-defined by widely used) - no intermediate conversion of fmt string to wide string - cleaner, easier to share code with strto* functions - better standards conformance for corner cases the old code remains in the source tree, as the wide versions of the scanf-family functions are still using it. it will be removed when no longer needed.
* add "scan helper getc" and rework strtod, etc. to use itRich Felker2012-04-101-0/+2
| | | | | | | | | | | | | | | | | | the immediate benefit is a significant debloating of the float parsing code by moving the responsibility for keeping track of the number of characters read to a different module. by linking shgetc with the stdio buffer logic, counting logic is defered to buffer refill time, keeping the calls to shgetc fast and light. in the future, shgetc will also be useful for integrating the new float code with scanf, which needs to not only count the characters consumed, but also limit the number of characters read based on field width specifiers. shgetc may also become a useful tool for simplifying the integer parsing code.
* add proper fuxed-based locking for stdioRich Felker2011-07-301-5/+4
| | | | | | | | | | | | | | | | | | | | | | previously, stdio used spinlocks, which would be unacceptable if we ever add support for thread priorities, and which yielded pathologically bad performance if an application attempted to use flockfile on a key file as a major/primary locking mechanism. i had held off on making this change for fear that it would hurt performance in the non-threaded case, but actually support for recursive locking had already inflicted that cost. by having the internal locking functions store a flag indicating whether they need to perform unlocking, rather than using the actual recursive lock counter, i was able to combine the conditionals at unlock time, eliminating any additional cost, and also avoid a nasty corner case where a huge number of calls to ftrylockfile could cause deadlock later at the point of internal locking. this commit also fixes some issues with usage of pthread_self conflicting with __attribute__((const)) which resulted in crashes with some compiler versions/optimizations, mainly in flockfile prior to pthread_create.
* clean up handling of thread/nothread mode, lockingRich Felker2011-04-171-1/+1
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* major stdio overhaul, using readv/writev, plus other changesRich Felker2011-03-281-12/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | the biggest change in this commit is that stdio now uses readv to fill the caller's buffer and the FILE buffer with a single syscall, and likewise writev to flush the FILE buffer and write out the caller's buffer in a single syscall. making this change required fundamental architectural changes to stdio, so i also made a number of other improvements in the process: - the implementation no longer assumes that further io will fail following errors, and no longer blocks io when the error flag is set (though the latter could easily be changed back if desired) - unbuffered mode is no longer implemented as a one-byte buffer. as a consequence, scanf unreading has to use ungetc, to the unget buffer has been enlarged to hold at least 2 wide characters. - the FILE structure has been rearranged to maintain the locations of the fields that might be used in glibc getc/putc type macros, while shrinking the structure to save some space. - error cases for fflush, fseek, etc. should be more correct. - library-internal macros are used for getc_unlocked and putc_unlocked now, eliminating some ugly code duplication. __uflow and __overflow are no longer used anywhere but these macros. switch to read or write mode is also separated so the code can be better shared, e.g. with ungetc. - lots of other small things.
* simplify and optimize FILE lock handlingRich Felker2011-03-241-3/+2
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* implement [v]swprintfRich Felker2011-03-181-1/+1
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* implement flockfile api, rework stdio lockingRich Felker2011-03-121-12/+7
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* initial check-in, version 0.5.0 v0.5.0Rich Felker2011-02-121-0/+100