Difference between revisions of "Library layering"
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==Problem== | ==Problem== | ||
| − | The three libraries libnetsnmpmibs, libnetsnmphelpers and libnetsnmpagent have circular dependencies instead of what should be a clean mibs -> helpers -> agent -> main library dependency chain | + | The three libraries libnetsnmpmibs, libnetsnmphelpers and libnetsnmpagent have circular dependencies instead of what should be a clean mibs -> helpers -> agent -> main library dependency chain: |
| + | |||
| + | * libnetsnmpmibs depends on libnetsnmphelpers | ||
| + | * both of these depend on libnetsnmpagent | ||
| + | * all 3 of these depend on libnetsnmp | ||
There are only a few problematic calls/functions that violate this dependency chain: | There are only a few problematic calls/functions that violate this dependency chain: | ||
Revision as of 19:33, 7 January 2007
Problem
The three libraries libnetsnmpmibs, libnetsnmphelpers and libnetsnmpagent have circular dependencies instead of what should be a clean mibs -> helpers -> agent -> main library dependency chain:
- libnetsnmpmibs depends on libnetsnmphelpers
- both of these depend on libnetsnmpagent
- all 3 of these depend on libnetsnmp
There are only a few problematic calls/functions that violate this dependency chain:
- libagent -> libhelpers:
- agent_registry.c: register_null, register_null_context and register_old_api
- snmp_agent.c: bulk_to_next_handler
- snmp_vars.c: init_helpers
Solutions
The brute-force approach is to move all three mibs/helpers/agent libraries into one huge libagent library again. Downside: even a minimal subagent needs to link in all the mib code which it shouldn't need.
The clever way would be to sensibly restructure the library while maintaining backward-compatibility and not causing too much overhead for agent developers. This needs to be investigated and discussed. Not sure if it's possible at all.
See the references below for the full discussion and details to date.
References
- 2006-10-19 #net-snmp IRC log
- Bug #1565496: library layering violation
- Bug #1619827: building with --as-needed is broken
