On 01.08.2013 07:46, Greg Stein wrote: > On Thu, Aug 1, 2013 at 12:20 AM, <br...@apache.org> wrote: >> Author: brane >> Date: Thu Aug 1 05:20:21 2013 >> New Revision: 1509080 >> >> URL: http://svn.apache.org/r1509080 >> Log: >> Begin extending spillbufs so that we can use them for compressed pristines. >> >> * subversion/libsvn_subr/spillbuf.c (svn_spillbuf_t): >> Add new fields delete_on_close, spill_all_contents, dirpath and temp_path. > Woah woah woah... Are you twisting a spillbuf into a buffered > file-write mechanism? > > I don't understand the motivation here. Spillbufs for for reading > *and* writing. Pristine creation is just writing.
The design for compressed pristines[citation required] assumes that small compressed pristine files will be stored entirely as blobs in a SQLite database, whereas large ones will be stored on-disk. This means we'll need "something" that can streamily compress to memory and copy said memory to a blob, or spill the whole compressed contents to disk if they exceed the threshold. Those "streamy", "write", "read" and "spill" requirements made me look at spillbufs -- and it turned out that they can be fairly easily modified to fit the bill for the backing store of a compressed-pristine (writer) stream, without impacting the features or performance of their current use case -- save for a few extra bytes in the spillbuf struct and an if or two in the code. -- Brane -- Branko Čibej | Director of Subversion WANdisco // Non-Stop Data e. br...@wandisco.com
