Evgeny Kotkov wrote:
Maybe we could start with adding a subsection about that describes using LZ4 for http:// and svn:// to the users. If needed, we could then include the technical details about the negotiation into the "Client-Server Protocol Changes" and cross-link these two sections.
Agreed. (And I think we should include protocol details -- at least a summary and references to where to find the details.)
For the http:// part, we could probably do something along the lines of the attached patch. Here is also the same content as plain text for convenience: [[[ LZ4 compression over the wire in http:// and svn:// connections Deltas transferred between Subversion 1.10 clients and servers may be compressed with LZ4. The actual choice of the compression algorithm depends on the used protocol, environment and its configuration — see below. For http:// protocol, use of LZ4 compression depends on the values of the server-side SVNCompressionLevel directive, client-side http-compression configuration option and on the network capabilities. LZ4 compression generally offers much faster compression and decompression speeds, but slightly worse compression ratio than zlib. By default, it is only preferred over low latency networks where the overhead associated with transferring the additional amount of data is assumed to be negligible. - On the server-side, SVNCompressionLevel 0 can be used to disable compression altogether. The special value of SVNCompressionLevel 1 forces the use of LZ4 compression for clients that support it. All other values result in negotiating the use of zlib compression with the respective compression level, unless the compression is disabled on the client.
There's a small disagreement with the table there: all other values result in negotiating either zlib or LZ4.
- On the client-side, setting http-compression to either yes or no will disable or enable compression that is then negotiated based on the server's configuration. The default value of auto will result in preferring LZ4 compression over low latency networks and zlib compression otherwise.
Can we link to the reference documentation for the client and server options, so the reader (me) can cross-check the definition and look for related settings?
Below is the table explaining the used compression algorithm in each combination of the client- and server-side configuration options:
That's helpful and clear. Thanks. +1 to commit after resolving the "all other values" point above. - Julian
