Hi everyone, Okay, I have a new wip-denc branch working and ready for some review: https://github.com/ceph/ceph/pull/11027 Highlights: - This includes appender/iterator changes to buffer* to speed up encoding and decoding (fewer bounds checks, simpler structures). - Accordingly, classes/types using the new-style have different arguments types for encode/decode. There is also a new bound_encode() method that is used to calculate how big of a buffer to preallocate. - Most of the important helpers for doing types have new versions that work with the new framework (e.g., the ENCODE_START macro has a new DENC_START counterpart). - There is also a mechanism that lets you define the bound_encode, encode, and decode methods all in one go using some template magic. This only works for pretty simple types, but it is handy. It looks like so: struct foo_t { uint32_t a, b; ... DENC(foo_t, v, p) { DENC_START(1, 1, p); denc(v.a, p); denc(v.b, p); ... DENC_FINISH(p); } }; WRITE_CLASS_DENC(foo_t) - For new-style types, a new 'denc' function that is overload to do either bound_encode, encode, or decode (based on argument types) is defined. That means that ::denc(v, p); will work for size_t& p, bufferptr::iterator& p, or bufferlist::contiguous_appender& p. This facilitates the DENC definitions above. - There is glue to invoke new-style encode/decode when old-style encode() and decode() are invoked, provided a denc_traits<T> is defined. - Most of the common containers are there list, vector, set, map, pair, but others need to be converted. - Currently, we're a bit aggressive about using the new-style over the old-style when we have the change. For example, if you have vector<int32_t> foo; ::encode(foo, bl); it will see that it knows how to do int32_t new-style and invoke the new-style vector<> code. I think this is going to be a net win, since we avoid doing bounds checks on append for every element (and the bound_encode is O(1) for thees base types). On the other hand, it is currently smart enough to not use new-style for individual integer types, like so int32_t v; ::encode(v, bl); although I suspect after the optimizer gets done with it the generated machine code is almost identical. - Most of the key bluestore types are converted over so that we can do some benchmarking. An overview is at the top of the new denc.h header here: https://github.com/liewegas/ceph/blob/wip-denc/src/include/denc.h#L55 I think I've captured the best of Allen's, Varada's, and Sam's various approaches, but we'll see how it behaves. Let me know what you think! Thanks- sage -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
