[Pharo-project] Basic tricks for improving a serializer?

Sven Van Caekenberghe sven at beta9.be
Wed May 18 14:53:37 CEST 2011


Mariano,

On 18 May 2011, at 14:29, Mariano Martinez Peck wrote:

> Sven, I improved quite a lot using your buffered write stream.
> What I don't understans is why MultiByteFileStream  doesn't perform as good as them.
> If I see StandardFileStream has an internal buffer called 'buffer1'. 
> 
> So why is that much difference between using MultiByteFileStream directly and
> a WriteStream (ByteArray new writeSteam ) or  ZnBufferedWriteStream ? 


I just looked briefly at the hierarchy, it seems that buffer1 is an output buffer of size 1 !

Have a look at 

StandardFileStream>>#nextPut: char
	"Write the given character to this file."

	rwmode ifFalse: [^ self error: 'Cannot write a read-only file'].
	collection ifNotNil: [ 
		position < readLimit ifTrue: [ self flushReadBuffer ] ].
	buffer1 at: 1 put: char.
	self primWrite: fileID from: buffer1 startingAt: 1 count: 1.
	^ char

There is simply no buffering going on.
buffer1 is a mystery to me ;-)

Sven

BTW: the above method flushes the READ buffer while WRITING,
there is probably an explanation for this, but I can't think of one.





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