HLClock v1.0.0 HLClock View Source
Hybrid Logical Clock
Provides globally-unique, monotonic timestamps. Timestamps are bounded by the clock synchronization constraint, max_drift. By default the max_drift is set to 300 seconds.
In order to account for physical time drift within the system, timestamps should regularly be exchanged between nodes. Generate a timestamp at one node via HLClock.send_timestamp/1; at the other node, call HLClock.recv_timestamp/2 with the received timestamp from the first node.
Inspired by https://www.cse.buffalo.edu/tech-reports/2014-04.pdf
Link to this section Summary
Functions
Determines if the clock's timestamp "happened before" a different timestamp
Returns a specification to start an HLClock.Server under a supervisor
Functionally equivalent to using send_timestamp/1. This generates a timestamp
for local causality tracking.
Given the current timestamp for this node and a provided remote timestamp, perform the merge of both logical time and logical counters. Returns the new current timestamp for the local node.
Generate a single HLC Timestamp for sending to other nodes or local causality tracking
Link to this section Functions
Determines if the clock's timestamp "happened before" a different timestamp
Returns a specification to start an HLClock.Server under a supervisor
In addition to standard GenServer opts, this allows for two other
options to be passed to the underlying server:
:node_id- a zero arity function returning a 64 bit integer for the node ID or a constant value that was precomputed prior to starting; defaults toHLClock.NodeId.hash/0:max_drift- the clock synchronization bound which is applied in either direction (i.e. timestamps are too far in the past or too far in the future); this value is in milliseconds and defaults to300_000
Functionally equivalent to using send_timestamp/1. This generates a timestamp
for local causality tracking.
Given the current timestamp for this node and a provided remote timestamp, perform the merge of both logical time and logical counters. Returns the new current timestamp for the local node.
Generate a single HLC Timestamp for sending to other nodes or local causality tracking