A Precedence Network (or Precedence diagram method) is a method of constructing connected activivies in a directed graph that specify dependencies. By specifyfing the minmimum, expected and maximum duration of each task the network can be analysed to find activities that sit on the critical path and must be completed on time to avoid delaying the entire network.
Given the following precedence network
text,ignore
┌──────────┐
┌────────────────►│Document:4├─────────────────┐
│ └──────────┘ │
│ ▼
┌────┴───┐ ┌─────────┐ ┌──────┐ ┌────────┐
│Design:5├──────►│Develop:6├────►│Test:4├─────►│Deploy:1│
└────────┘ └──────┬──┘ └──────┘ └────────┘
│ ▲
│ ┌───────┐ │
└────────►│Train:3├─────────┘
└───────┘
Using precedence-net we can model it with the following code
```rust use precedence_net::{Network, Result};
fn main() -> Result<()> { let mut network_builder = Network::builder();
networkbuilder.addactivity("Design", 5.0)?; networkbuilder.addactivity("Develop", 6.0)?; networkbuilder.addactivity("Document", 4.0)?; networkbuilder.addactivity("Deploy", 1.0)?; networkbuilder.addactivity("Train", 3.0)?; networkbuilder.addactivity("Test", 4.0)?;
networkbuilder.connect("Design", "Develop")?; networkbuilder.connect("Design", "Document")?; networkbuilder.connect("Develop", "Test")?; networkbuilder.connect("Develop", "Train")?; networkbuilder.connect("Test", "Deploy")?; networkbuilder.connect("Train", "Deploy")?; network_builder.connect("Document", "Deploy")?;
let network = Network::tryfrom(networkbuilder)?;
println!("Activity | Earliest Start | Earliest Finish | Latest Start | Latest Finish | Total Float | Free Float | Critical Path");
println!("---------------------------------------------------------------------------------------------------------------------");
for activity in network.activities()? {
println!(
"{:^8} | {:>14} | {:>15} | {:>12} | {:>13} | {:>11} | {:>10} | {:^14}",
activity,
network.earlieststart(activity)?,
network.earliestfinish(activity)?,
network.lateststart(activity)?,
network.latestfinish(activity)?,
network.totalfloat(activity)?,
network.freefloat(activity)?,
network.oncriticalpath(activity)?,
);
}
Ok(())
}
will produce the following output
text,ignore
Design | 0 | 5 | 0 | 5 | 0 | 0 | true Develop | 5 | 11 | 5 | 11 | 0 | 0 | true Document | 5 | 9 | 11 | 15 | 6 | 6 | false Test | 11 | 15 | 11 | 15 | 0 | 0 | true Train | 11 | 14 | 12 | 15 | 1 | 1 | false Deploy | 15 | 16 | 15 | 16 | 0 | 0 | true ```
Using Criterion.rs the following activities were benchmarked for a precedence network of 62 500 activities on an Intel Core i7 with 16GB RAM.
The disparity in times between [NetworkBuilder] -> [Network] and [Network] -> [NetworkBuilder] processes is due to the fact that during the conversion process all the early start/early finish/late start/late finish calculations are performed and cached in the [Network].
Copyright 2022 Farrel Lifson
Released under the MIT License. See LICENSE-MIT for details.