PS: I have created a Jira and have published the following RRs: 1. https://reviews.apache.org/r/30294/ 2. https://reviews.apache.org/r/30295/ 3. https://reviews.apache.org/r/30300/
On Tue, Jan 27, 2015 at 1:50 AM, Kapil Arya <[email protected]> wrote: > Hi Jie, > > Thanks for the comments. I have tried to answer them inline. Please let us > know if something isn't clear. > > Kapil > > On Tue, Jan 27, 2015 at 1:25 AM, Jie Yu <[email protected]> wrote: > >> One benefit of having an internal namespace is that it tells the >> framework/executor writer that those symbols/method/class are internal to >> Mesos core and should not be used. >> > > We don't have any internal symbols/methods/classes in public headers, do > we? This is assuming that a framework writer installs a mesos-dev package > or equivalent and doesn't deal with mesos source tree. > > >> If we kill all the internal namespaces and move many headers like >> isolator.hpp to include/mesos, how does the framework writer know that >> he/she shouldn't use some of the headers because they are internal to >> Mesos >> and are subject to change? >> > > I do agree on your general point about exposing more files to framework > writers. However, shouldn't a framework writer be using the headers, etc. > based on their requirements rather than grabbing anything and everything > that is exposed as public headers? > > >> >> For modules, I am wondering can we separate Mesos public headers (in >> include/mesos right now) from those headers that are only for building >> modules (more like internal public headers). >> > > It's a bit complicated. There are some files that correspond only to the > slave (i.e. mesos/slave/state.hpp, mesos/slave/isolator.hpp) and similarly, > very soon we'll have master-specific files as well. Similarly, there are > some shared files such as those authenticator/authenticatee, that are > shared by both master and slave. In all these cases, these files aren't > just about modules, instead, modules are only _one_ of the consumers of > these files. > > Further, module-specific files currently reside in mesos/module/. As per > the current file layout, files in mesos/module/ #include files from mesos/. > For example, mesos/module/isolator.hpp #includes mesos/slave/isolator.hpp. > > Is there an alternate file layout suggestion that we should think about? > > >> Thoughts? >> >> - Jie >> >> On Mon, Jan 26, 2015 at 12:35 PM, Kapil Arya <[email protected]> wrote: >> >> > Hi All, >> > >> > TLDR: We currently use "mesos::internal" namespace for almost everything >> > inside src/. However, in most cases, it is directly enclosing another >> > namespace. This makes the "internal" namespace redundant and we should >> > kill it. >> > >> > I learned from Ben Hindman that the original motivation for introducing >> an >> > explicit internal namespace was to discourage people from exposing >> internal >> > symbols through "extern", etc. Since we don't seem to expose symbols >> > through "extern" in our codebase, I think it's safe to kill this >> namespace. >> > >> > Here is a list of files that define classes directly in the >> mesos::internal >> > namespace (i.e. without enclosing a separate namespace) [1]: >> > >> > authorizer/authorizer.hpp >> > common/http.hpp >> > common/attributes.hpp >> > common/lock.hpp >> > files/files.hpp >> > hook/manager.hpp >> > master/contender.hpp >> > master/detector.hpp >> > usage/usage.hpp >> > watcher/whitelist_watcher.hpp >> > >> > messages/messages.pb.h >> > >> > Of the above list, things like hook/manager.hpp and >> > master/{contender,detector}.hpp can be moved into their own >> namespaces. I >> > am sure, we can come up with a strategy for the rest as well. >> > >> > One possible concern here might be messages.proto and the effects on >> > upgrades, etc., if we change the namespace/package for these >> protobufs. If >> > this turns out to be a real concern, we can possibly keep the internal >> > namespace for messages.proto. >> > >> > If we kill the "internal" namespace altogether, it would make it much >> > easier to expose some headers as public headers for modularization, >> etc.. >> > This will also help us get rid of "namespace internal" from some of the >> > public headers that we already have. >> > >> > The motivation for killing the "internal" namespace comes from a >> > patch-set[2] that tries to expose slave/containerizer/isolator.hpp as >> > include/mesos/slave/isolator.hpp. We wanted to keep Isolator inside the >> > "mesos::slave" namespace instead of putting it directly in the "mesos" >> > namespace. This change causes a lot of conflicts due to "mesos::slave" >> and >> > "mesos::internal::slave" and we had to resort to using fully qualified >> > names for a large number of definition in src/slave, src/tests, etc. >> > >> > Best, >> > Kapil >> > >> > [1] List obtained by running the following command and then filtering >> out >> > the instances where "internal" was enclosed in something other than >> > "mesos": >> > grep -nr "} // namespace internal" * -B1 |grep -v >> > "namespace\|\-\-\|\.cpp"|cut -d'-' -f1 >> > >> > [2] https://reviews.apache.org/r/30238/ >> > https://reviews.apache.org/r/29602/ >> > https://reviews.apache.org/r/29603/ >> > >> > >
