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Draft 0.5 is now complete, I think, hooray!

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Scott Lystig Fritchie 2015-04-22 23:06:46 +09:00
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doc/src.high-level/high-level-chain-mgr.tex
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@ -552,7 +552,7 @@ unanimous value $V_{u}$ for the projection at epoch $E$, then $V_{u}$
is use to repair all projections stores at $E$ that contain $\bot$ is use to repair all projections stores at $E$ that contain $\bot$
values. If the value of $K$ is not unanimous, then the ``highest values. If the value of $K$ is not unanimous, then the ``highest
ranked value'' $V_{best}$ is used for the repair; see ranked value'' $V_{best}$ is used for the repair; see
Section~\ref{sub:projection-ranking} for a description of projection Section~\ref{sub:ranking-projections} for a description of projection
ranking. ranking.
\subsection{Writing to public projection stores} \subsection{Writing to public projection stores}
@ -796,10 +796,8 @@ is used by the flowchart and throughout this section.
\begin{description} \begin{description}
\item[Author] The name of the server that created the projection. \item[Author] The name of the server that created the projection.
\item[Rank] Assigns a numeric score to a projection. Rank is based on the \item[Rank] Assigns a numeric score to a projection, see
epoch number (higher wins), chain length (larger wins), number \& Section~\ref{sub:ranking-projections}.
state of any repairing members of the chain (larger wins), and node
name of the author server (as a tie-breaking criteria).
\item[E] The epoch number of a projection. \item[E] The epoch number of a projection.
@ -978,7 +976,7 @@ knows that an environment change has happened and wishes to trigger a
response prior to the next timer firing. response prior to the next timer firing.
It's recommended that the timer interval be staggered according to the It's recommended that the timer interval be staggered according to the
participant ranking rules in Section~\ref{sub:projection-ranking}; participant ranking rules in Section~\ref{sub:ranking-projections};
higher-ranked servers use shorter timer intervals. Timer staggering higher-ranked servers use shorter timer intervals. Timer staggering
is not required, but the total amount of churn (as measured by is not required, but the total amount of churn (as measured by
suggested projections that are ignored or immediately replaced by a suggested projections that are ignored or immediately replaced by a
@ -1096,8 +1094,28 @@ trigger the projection calculation subsystem to create an alternative,
safe projection $P_{latest+1}$ that will hopefully create a unanimous safe projection $P_{latest+1}$ that will hopefully create a unanimous
epoch $E+1$. epoch $E+1$.
See Section~\ref{sub:humming-rules-and-invariants} for detail about The transition from $P_{current} \rightarrow P_{latest}$ is checked
these rules and invariants. for safety and sanity. The conditions used for the check include:
\begin{enumerate}
\item The Erlang data types of all record members are correct.
\item UPI, down, and repairing lists contain no duplicates and are in fact
mutually disjoint.
\item The author node is not down (as far as we can tell).
\item Any server $N$ that was added to $P_{latest}$'s UPI list must
appear in the tail the UPI list, and $N$ must have been in
$P_{current}$'s repairing list.
\item No re-ordering of the UPI list members: any server $S$ that is
in $P_{latest}$'s UPI list that was not present in $P_{current}$'s
UPI list must in the same position as it appeared in $P_{current}$'s
UPI list. The same re-reordering restriction applies to all
servers in $P_{latest}$'s repairing list relative to
$P_{current}$'s repairing list.
\end{enumerate}
The safety check may be performed pair-wise once or pair-wise across
the entire history sequence of a server/FLU's private projection
store.
\subsection{Additional discussion of flapping state} \subsection{Additional discussion of flapping state}
\label{sub:flapping-state} \label{sub:flapping-state}
@ -1246,10 +1264,13 @@ where ``flapping'' will continue on every humming consensus iteration
until all asymmetric partition disappears. Such proof is an area of until all asymmetric partition disappears. Such proof is an area of
future work. future work.
\subsection{ranking} \subsection{Ranking projections}
\label{sub:projection-ranking} \label{sub:ranking-projections}
TODO A projection's rank is based on the epoch number (higher always wins),
chain length (larger wins), number \& state of any repairing members
of the chain (larger wins), and node name of the author server (as a
tie-breaking criteria).
\section{``Split brain'' management in CP Mode} \section{``Split brain'' management in CP Mode}
\label{sec:split-brain-management} \label{sec:split-brain-management}
@ -1908,12 +1929,6 @@ immensely: Justin Sheehy, Kota Uenishi, Shunichi Shinohara, Andrew
Stone, Jon Meredith, Chris Meiklejohn, Mark Allen, and Zeeshan Stone, Jon Meredith, Chris Meiklejohn, Mark Allen, and Zeeshan
Lakhani. Lakhani.
\section{TODO: orphaned text \& missing stuff}
\subsection{rules \& invariants}
\label{sub:humming-rules-and-invariants}
\bibliographystyle{abbrvnat} \bibliographystyle{abbrvnat}
\begin{thebibliography}{} \begin{thebibliography}{}
\softraggedright \softraggedright