Immediate start of federates with STA offset under decentralized coordination #469
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Actionable comments posted: 0
Outside diff range, codebase verification and nitpick comments (1)
core/threaded/reactor_threaded.c (1)
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209-245: Handling of STA offset is robust, but could use clearer documentation.The function
wait_untilmanages the STA offset well by adjusting the logical time to include it, which is crucial for correct synchronization in federated decentralized systems. However, the comments could be enhanced to clarify the role and impact of the STA offset in preventing overflows and ensuring timely starts.// Apply the STA to the logical time // Prevent an overflow - // If wait_time is not forever + // Adjust wait time to include STA offset, ensuring it does not exceed FOREVER
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- core/threaded/reactor_threaded.c (2 hunks)
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core/threaded/reactor_threaded.c (2)
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30-58: Well-implemented tag barrier logic.The function
_lf_increment_tag_barrier_lockedcorrectly manages the tag barriers, ensuring logical time synchronization in federated environments. The checks and adjustments forfuture_tagare appropriately handled.
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97-124: Effective management of theFOREVERtag in barriers.The function
_lf_wait_on_tag_barrierproperly handles cases whereproposed_tag.time == FOREVER, preventing unnecessary waits and aligning with the PR's objective of immediate thread start-up in federated environments whenSTP_offsetis set toFOREVER.
An STA_offset of T (which should be called STA, safe to advance) means that at physical time t+T the federate can assume it has received all messages with tags less than t. If t is the start time, the federate already knows it has received all messages with tags less than t (because there are no messages with tags less than t). Hence, at the start time, there is no need to wait. This change enables very simple use of decentralized coordination for a subset of LF programs that do not deal with time, but rather just deal with data flow. |
Allow dataflow-like behavior when setting STP_offset to infinity
lhstrh
changed the title
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I adjusted the title of the PR to match what I think this does, but I'm not sure I got it right... |
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@edwardalee please also update the description (it doesn't seem like this PR enables data-flow-like behavior as it only affects the behavior at startup?) |
In decentralized coordination, the behavior used to be to wait for
STP_offsetbefore starting the worker threads. With this change, the federates start immediately without waiting forSTP_offset.When the user sets to
STP_offsettoFOREVER, it enables dataflow-like behavior.Summary by CodeRabbit