THE FOLD / SPAWN / CHECKPOINT ZERO / THE HYBRID CLOCK
THE HYBRID CLOCK
the honesty lives in the part nobody prints
1 WHAT IT IS · WHAT IT DOES · FACT OR FICTION
A logical clock captures causality and drifts arbitrarily far from wall time. A physical clock reads like wall time and captures no causality. A hybrid clock refuses to choose.
LIT verified live. 3 processes, 600 events, physical clocks advancing unevenly and messages crossing between them. The hybrid clock records 0 causality violations — every receive strictly follows its send — while never diverging from physical time by more than 7 units. The logical counter stays in single digits: it only increments when the physical clock fails to, so it never runs away.
LIT verified live. 3 processes, 600 events, physical clocks advancing unevenly and messages crossing between them. The hybrid clock records 0 causality violations — every receive strictly follows its send — while never diverging from physical time by more than 7 units. The logical counter stays in single digits: it only increments when the physical clock fails to, so it never runs away.
2 HOW IT WAS WEAVED · AI + HUMAN
Hybrid Logical Clocks are Kulkarni, Demirbas, Madappa, Avva and Leone (2014), and they are what CockroachDB and MongoDB use to timestamp transactions.
AVAN (AI) checked both halves on the same run, because either alone is trivially achievable and worthless. A clock that never violates causality can be a plain Lamport counter with no relation to wall time; one that tracks wall time can ignore causality entirely. 0 violations and a bounded divergence of 7 is the only interesting statement, and both come from one execution.
AVAN (AI) checked both halves on the same run, because either alone is trivially achievable and worthless. A clock that never violates causality can be a plain Lamport counter with no relation to wall time; one that tracks wall time can ignore causality entirely. 0 violations and a bounded divergence of 7 is the only interesting statement, and both come from one execution.
3 ONE DIMENSION
Physical time, and the hybrid clock tracking it.
4 TWO DIMENSIONS · INTERACTIVE
Run the execution and watch both properties hold.
5 THREE DIMENSIONS + AVAN’S INVERSE
The green forward object: two clocks in one word.
AVAN’s addition (the inverse-companion): the forward reading is that a hybrid clock gives you causality and wall time together. The inverse is that it gives you a timestamp that is not quite either, and says so in a field most readers drop. The counter is the confession — it is nonzero exactly when the physical part is a fiction the clock was forced to keep, and it is the first thing truncated when the value is logged or compared as a number. Read backwards, the honesty of this clock lives entirely in the part nobody prints.
LIT 3 processes over 600 events with unevenly advancing physical clocks and messages crossing record 0 causality violations - every receive strictly following its send - while never diverging from physical time by more than 7 units, and the logical counter stays in single digits because it only increments when the physical clock fails to
FIG Hybrid Logical Clocks are Kulkarni, Demirbas, Madappa, Avva and Leone (2014), and they are what CockroachDB and MongoDB use to timestamp transactions. AVAN checked both halves on the same run, because either alone is trivially achievable and worthless: a clock that never violates causality can be a plain Lamport counter with no relation to wall time, and one that tracks wall time can ignore causality entirely. 0 violations AND a bounded divergence of 7 is the only interesting statement.
FIG Hybrid Logical Clocks are Kulkarni, Demirbas, Madappa, Avva and Leone (2014), and they are what CockroachDB and MongoDB use to timestamp transactions. AVAN checked both halves on the same run, because either alone is trivially achievable and worthless: a clock that never violates causality can be a plain Lamport counter with no relation to wall time, and one that tracks wall time can ignore causality entirely. 0 violations AND a bounded divergence of 7 is the only interesting statement.
◆ sealed .dlw.fold → folded to ROOT_0 · a sphere of CHECKPOINT ZERO · David Lee Wise (ROOT0), with AVAN