> On Jan. 30, 2014, 7:59 p.m., Jie Yu wrote: > > src/state/log.cpp, line 94 > > <https://reviews.apache.org/r/17423/diff/1/?file=451877#file451877line94> > > > > We can kill this if the following patch is out: > > https://reviews.apache.org/r/17476/ > > > > Replace it with a Sequence object.
I've decided to move to an "asynchronous" mutex instead. This is really simpler to reason about (now that the discard semantics have changed) and doesn't require adding overloads to Sequence for both C++03 and C++11. > On Jan. 30, 2014, 7:59 p.m., Jie Yu wrote: > > src/state/log.cpp, line 297 > > <https://reviews.apache.org/r/17423/diff/1/?file=451877#file451877line297> > > > > Comments about why atomicity can be achieved here might be great. For > > example, I may wonder: is it possible that some other writer gets elected > > and writes the same variable ahead in the log while this writer does not > > know about it and somehow is writing a 'hole' in the log (and succeeds). In > > that case, the other writer's append may not be atomic. > > > > I guess one important invariant here is: when a writer successfully > > appends a value to the log (at position p), all values at positions prior > > to p should have been agreed and properly replayed (thus reflected in the > > in-memory snapshots). The atomicity here is guaranteed because of the nature of starting a Log::Writer and doing an append. Now that Log::Writer demotion is exposed (via returning options) we're guaranteed to know when something that we tried to do was no longer atomic. I've added some small comments as such to the LogStorageProcess class. - Benjamin ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/17423/#review33233 ----------------------------------------------------------- On Jan. 27, 2014, 9:33 p.m., Benjamin Hindman wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://reviews.apache.org/r/17423/ > ----------------------------------------------------------- > > (Updated Jan. 27, 2014, 9:33 p.m.) > > > Review request for mesos, Ben Mahler and Jie Yu. > > > Repository: mesos-git > > > Description > ------- > > This is done in C++11, I've converted to C++03 in > https://reviews.apache.org/r/17424. > > Note that this does not implement diffs but that's probably okay for our > initial use case. This also does not implement caching so all state entries > are stored in memory, which is also okay for our initial use case. Finally, > this does not implement defragmentation which again is probably okay for our > use case. These are captured as TODOs in the code. > > Also, this uses a 'sequence' operation which will be replaced with work being > done by Jie Yu. > > > Diffs > ----- > > src/Makefile.am d58b46e99e0a041cf2a26abe44bbd1504a9539c0 > src/messages/state.proto 7f7a8a505d6f24b01fec0c3ad47b0e15b2b17ffa > src/state/log.hpp PRE-CREATION > src/state/log.cpp PRE-CREATION > src/tests/log_tests.cpp e493af4f2f2435efe168d07acd267b61afd37fe4 > src/tests/state_tests.cpp 03c538861a88d3a07e2468dce5553eeb3acc9243 > > Diff: https://reviews.apache.org/r/17423/diff/ > > > Testing > ------- > > make check > > > Thanks, > > Benjamin Hindman > >
