App realm bootstrap vtable

[sbahirnv]

Realm Bootstrap Example

Shows how an application can configure Realm's bootstrap using a key-value interface.

The sample_app.cc main function represents an application like Dynamo or Flashcache that links against Realm. The realm_bootstrap.h and realm_bootstrap.cc files implement Realm's bootstrap_handle_t contract, providing the required interface.

Building

mkdir build && cd build
cmake ..
make

Running

mpirun -n 4 ./sample_app

What It Does

The app implements a bootstrap_handle_t using environment variables as the communication mode. The get() function reads from getenv(), and init() writes with setenv() - both use the same mechanism.

The init() function sets example keys that Realm could read:

• REALM_COMM_MODE=env - communication mode (env, etcd, pmix)
• REALM_BOOTSTRAP_TYPE=mpi - bootstrap mechanism (mpi, p2p, etc)

Realm uses the same bootstrap_handle_t interface regardless of the underlying communication mode. The application chooses the mode (environment variables, etcd, pmix, etc.) and implements all functions consistently with that choice. Future versions could switch to etcd or other distributed stores by changing only the implementation, not the interface.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 27.74%. Comparing base (c50faeb) to head (43f79be).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #364      +/-   ##
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- Coverage   27.75%   27.74%   -0.01%     
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  Files         191      191              
  Lines       39499    39499              
  Branches    14223    14382     +159     
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- Hits        10961    10960       -1     
- Misses      27261    28147     +886     
+ Partials     1277      392     -885     

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[sbahirnv]

The main discussion about realm network vtable and bootstrapping is happening on the PR-https://github.com/StanfordLegion/realm/pull/366.

Closing this MR.