A large part of this change contains surface-level
porting, like moving variable declarations to the
top of the block.
However there are a few more substantial things too:
- moved internal-only struct definitions to a separate
file (structdefs.int.h), for greater encapsulation
and ABI compatibility.
- removed the UPB_UPCAST macro, since it requires access
to the internal-only struct definitions. Replaced uses
with calls to inline, type-safe casting functions.
- removed the UPB_DEFINE_CLASS/UPB_DEFINE_STRUCT macros.
Class and struct definitions are now more explicit -- you
get to see the actual class/struct keywords in the source.
The casting convenience functions have been moved into
UPB_DECLARE_DERIVED_TYPE() and UPB_DECLARE_DERIVED_TYPE2().
- the new way that we duplicate base methods in derived types
is also more convenient and requires less duplication.
It is also less greppable, but hopefully that is not
too big a problem.
Compiler flags (-std=c89 -pedantic) should help to rigorously
enforce that the code is free of C99-isms.
A few functions are not available in C89 (strtoll). There
are temporary, hacky solutions in place.
- rewritten decoder; interpreted decoder is bytecode-based,
JIT decoder no longer falls back to the interpreter.
- C++ improvements: C++11-compatible iterators, upb::reffed_ptr
for RAII refcounting, better upcast/downcast support.
- removed the gross upb_value abstraction from public upb.h.
Major changes:
- Got rid of all bytestream interfaces in favor of
using regular handlers.
- new Pipeline object represents a upb pipeline, does
bump allocation internally to manage memory.
- proto2 support now can handle extensions.
Many things have changed and been simplified.
The memory-management story for upb_def and upb_handlers
is much more robust; upb_def and upb_handlers should be
fairly stable interfaces now. There is still much work
to do for the runtime component (upb_sink).
Many improvements, too many to mention. One significant
perf regression warrants investigation:
omitfp.parsetoproto2_googlemessage1.upb_jit: 343 -> 252 (-26.53)
plain.parsetoproto2_googlemessage1.upb_jit: 334 -> 251 (-24.85)
25% regression for this benchmark is bad, but since I don't think
there's any fundamental design issue that caused it I'm going to
go ahead with the commit anyway. Can investigate and fix later.
Other benchmarks were neutral or showed slight improvement.
Added a upb_byteregion that tracks a region of
the input buffer; decoders use this instead of
using a upb_bytesrc directly. upb_byteregion
is also used as the way of passing a string to
a upb_handlers callback. This symmetry makes
decoders compose better; if you want to take
a parsed string and decode it as something else,
you can take the string directly from the callback
and feed it as input to another parser.
A commented-out version of a pinning interface
is present; I decline to actually implement it
(and accept its extra complexity) until/unless
it is clear that it is actually a win. But it
is included as a proof-of-concept, to show that
it fits well with the existing interface.
Includes are now via upb/foo.h.
Files specific to the protobuf format are
now in upb/pb (the core library is concerned
with message definitions, handlers, and
byte streams, but knows nothing about any
particular serializationf format).
I'm realizing that basically all upb objects
will need to be refcounted to be sharable
across languages, but *not* messages which
are on their way out so we can get out of
the business of data representations.
Things which must be refcounted:
- encoders, decoders
- handlers objects
- defs
It can successfully parse SpeedMessage1.
Preliminary results: 750MB/s on Core2 2.4GHz.
This number is 2.5x proto2.
This isn't apples-to-apples, because
proto2 is parsing to a struct and we are
just doing stream parsing, but for apps
that are currently using proto2, this is the
improvement they would see if they could
move to stream-based processing.
Unfortunately perf-regression-test.py is
broken, and I'm not 100% sure why. It would
be nice to fix it first (to ensure that
there are no performance regressions for
the table-based decoder) but I'm really
impatient to get the JIT checked in.
This doesn't reflect any material change in
how I will be working on upb, and I have no
problem making this change. It's still open
source under the BSD license, and I'll still
be working on it well beyond the hours that
constitute a normal job.
This is a significant change to the upb_stream
protocol, and should hopefully be the last
significant change.
All callbacks are now registered ahead-of-time
instead of having delegated callbacks registered
at runtime, which makes it much easier to
aggressively optimize ahead-of-time (like with a
JIT).
Other impacts of this change:
- You no longer need to have loaded descriptor.proto
as a upb_def to load other descriptors! This means
the special-case code we used for bootstrapping is
no longer necessary, and we no longer need to link
the descriptor for descriptor.proto into upb.
- A client can now register any upb_value as what
will be delivered to their value callback, not
just a upb_fielddef*. This should allow for other
clients to get more bang out of the streaming
decoder.
This change unfortunately causes a bit of a performance
regression -- I think largely due to highly
suboptimal code that GCC generates when structs
are returned by value. See:
http://blog.reverberate.org/2011/03/19/when-a-compilers-slow-code-actually-bites-you/
On the other hand, once we have a JIT this should
no longer matter.
Performance numbers:
plain.parsestream_googlemessage1.upb_table: 374 -> 396 (5.88)
plain.parsestream_googlemessage2.upb_table: 616 -> 449 (-27.11)
plain.parsetostruct_googlemessage1.upb_table_byref: 268 -> 269 (0.37)
plain.parsetostruct_googlemessage1.upb_table_byval: 215 -> 204 (-5.12)
plain.parsetostruct_googlemessage2.upb_table_byref: 307 -> 281 (-8.47)
plain.parsetostruct_googlemessage2.upb_table_byval: 297 -> 272 (-8.42)
omitfp.parsestream_googlemessage1.upb_table: 423 -> 410 (-3.07)
omitfp.parsestream_googlemessage2.upb_table: 679 -> 483 (-28.87)
omitfp.parsetostruct_googlemessage1.upb_table_byref: 287 -> 282 (-1.74)
omitfp.parsetostruct_googlemessage1.upb_table_byval: 226 -> 219 (-3.10)
omitfp.parsetostruct_googlemessage2.upb_table_byref: 315 -> 298 (-5.40)
omitfp.parsetostruct_googlemessage2.upb_table_byval: 297 -> 287 (-3.37)
The symtab that contains them is now hidden, and
you can look them up by name but there is no access
to the symtab itself, so there is no risk of
mutating it (by extending it, adding other defs
to it, etc).
Josh Haberman
Josh Haberman
Joshua Haberman