On Tue, 24 Jul 2012 12:07:55 +0200 Simon Toedt wrote:
> Can I deallocate individual strings in a sfio stream? How long is the
> lifetime of a string in a sfio string stream anyway, i.e. when is it
> deallocated? How does sfseek() affect this?
it depends on whether you use stk*() or sfstr*()
in general though they each are conceptually a linear stream of bytes
seek operations can shrink the virtual length
but the underlying allocated chunks will remain for the life of the stream
stkset() can return allocated data after the current object
sfstr*() does not have a way to return unused data other then sfstrclose()
if you have a situation like
^ used ^ not-used ^ used ^
the not-used will still take up allocated space -- i.e., not-used is a caller
concept,
not an sfio concept w.r.t. string streams
nmake will typically juggle 1 <= n < 10 string streams, each from a separate
sfstropen()
the most common operation is to read from one string stream
apply a transformation
and write to another string stream
for both stk*() and sfstr*() you can seek to the beginning of the stream
this puts the stream in an initial state, ready for writing
another ast paradigm is to use vmalloc(3) regions for building complex data
structures
each piece can be allocated by separate allocations, and vmfree() will also
return
unused space to the region -- when you are done just call vmclose() and
everything
is returned -- this libast code uses this method:
src/lib/libast/misc/fastfind.c
src/lib/libast/misc/magic.c
src/lib/libast/misc/mc.c
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