Chris Lattner wrote:
>> Use the stat information in the Path object, if it is already
>> obtained. This
>> avoids a call to ::fstat by MappedFile when the file size
>> information was
>> already obtained by the Path object.
>>
>
> Interesting approach. The problem is that fstat is significantly
> faster than stat. How about a new Path::getFileStatusFromFD()
> method, which takes an open file descriptor. If the System supports
> it, it can get status information faster by using it, otherwise it
> falls back to getFileStatus (e.g. if win32 doesn't have fstat)?
>
> -Chris
>
It does, but names it _fstat. I'm not sure it's worth the bother to
cache fstat either. stat is slow because it has to look up the file path.
>
>> ---
>> Diffs of the changes: (+3 -4)
>>
>> MappedFile.inc | 7 +++----
>> 1 files changed, 3 insertions(+), 4 deletions(-)
>>
>>
>> Index: llvm/lib/System/Unix/MappedFile.inc
>> diff -u llvm/lib/System/Unix/MappedFile.inc:1.18 llvm/lib/System/
>> Unix/MappedFile.inc:1.19
>> --- llvm/lib/System/Unix/MappedFile.inc:1.18 Fri Aug 25 16:37:17 2006
>> +++ llvm/lib/System/Unix/MappedFile.inc Thu Mar 29 14:11:22 2007
>> @@ -54,15 +54,14 @@
>> MakeErrMsg(ErrMsg, "can't open file '" + path_.toString() + "'");
>> return true;
>> }
>> - struct stat sbuf;
>> - if(::fstat(FD, &sbuf) < 0) {
>> - MakeErrMsg(ErrMsg, "can't stat file '"+ path_.toString() + "'");
>> + const FileStatus *Status = path_.getFileStatus(false, ErrMsg);
>> + if (!Status) {
>> ::close(FD);
>> return true;
>> }
>> info_ = new MappedFileInfo;
>> info_->FD = FD;
>> - info_->Size = sbuf.st_size;
>> + info_->Size = Status->getSize();
>> return false;
>> }
>>
>>
>>
>>
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