partisan
partisan
v5.0.0-rc.8

View Source partisan_vclock (partisan v5.0.0-rc.8)

A simple Erlang implementation of vector clocks as inspired by Lamport logical clocks. Taken from Riak.

Summary

Types

binary_vclock/0
The timestamp is present but not used, in case a client wishes to inspect it.
counter/0
vc_entry/0
vclock/0
vclock_node/0

Functions

all_nodes(VClock)
Return the list of all nodes that have ever incremented VClock.
descends(Va, Vb)
Return true if Va is a direct descendant of Vb, else false -- remember, a vclock is its own descendant!
dominates(A, B)
equal(VClockA, VClockB)
Compares two VClocks for equality.
fresh()
Create a brand new vclock.
from_binary(Bin)
takes the output of to_binary/1 and returns a vclock
get_counter(Node, VClock)
Get the counter value in VClock set from Node.
glb(Clock1, Clock2)
take two vclocks and return a vclock that summerizes only the events both have seen.
increment(Node, VClock)
Increment VClock at Node.
merge(VClocks)
Combine all VClocks in the input list into their least possible common descendant.
subtract_dots(DotList, VClock)
subtract the VClock from the DotList. what this means is that any {actor(), count()} pair in DotList that is <= an entry in VClock is removed from DotList Example [{a, 3}, {b, 2}, {d, 14}, {g, 22}] - [{a, 4}, {b, 1}, {c, 1}, {d, 14}, {e, 5}, {f, 2}] = [{{b, 2}, {g, 22}]
to_binary(Clock)
an efficient format for disk / wire. 5 @see from_binary/1

Types

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binary_vclock/0

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-type binary_vclock() :: binary().
The timestamp is present but not used, in case a client wishes to inspect it.
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counter/0

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-type counter() :: integer().
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vc_entry/0

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-type vc_entry() :: {vclock_node(), counter()}.
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vclock/0

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-type vclock() :: [vc_entry()].
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vclock_node/0

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-type vclock_node() :: term().

Functions

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all_nodes(VClock)

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-spec all_nodes(VClock :: vclock()) -> [vclock_node()].
Return the list of all nodes that have ever incremented VClock.
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descends(Va, Vb)

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-spec descends(Va :: vclock() | [], Vb :: vclock() | []) -> boolean().
Return true if Va is a direct descendant of Vb, else false -- remember, a vclock is its own descendant!
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dominates(A, B)

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-spec dominates(vclock(), vclock()) -> boolean().
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equal(VClockA, VClockB)

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-spec equal(VClockA :: vclock(), VClockB :: vclock()) -> boolean().
Compares two VClocks for equality.
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fresh()

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-spec fresh() -> vclock().
Create a brand new vclock.
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from_binary(Bin)

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-spec from_binary(binary_vclock()) -> vclock().
takes the output of to_binary/1 and returns a vclock
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get_counter(Node, VClock)

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-spec get_counter(Node :: vclock_node(), VClock :: vclock()) -> counter().
Get the counter value in VClock set from Node.
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glb(Clock1, Clock2)

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-spec glb(vclock(), vclock()) -> vclock().
take two vclocks and return a vclock that summerizes only the events both have seen.
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increment(Node, VClock)

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-spec increment(Node :: vclock_node(), VClock :: vclock()) -> vclock().
Increment VClock at Node.
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merge(VClocks)

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-spec merge(VClocks :: [vclock()]) -> vclock() | [].
Combine all VClocks in the input list into their least possible common descendant.
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subtract_dots(DotList, VClock)

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-spec subtract_dots(vclock(), vclock()) -> vclock().
subtract the VClock from the DotList. what this means is that any {actor(), count()} pair in DotList that is <= an entry in VClock is removed from DotList Example [{a, 3}, {b, 2}, {d, 14}, {g, 22}] - [{a, 4}, {b, 1}, {c, 1}, {d, 14}, {e, 5}, {f, 2}] = [{{b, 2}, {g, 22}]
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to_binary(Clock)

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-spec to_binary(vclock()) -> binary_vclock().
an efficient format for disk / wire. 5 @see from_binary/1