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synchronous graph
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use std::sync::{Arc, Mutex, Weak}; | |
use std::clone::Clone; | |
#[derive(Debug, Clone)] | |
struct GraphInner<T> { | |
nodes: Vec<(Option<Arc<Mutex<NodeInner<T>>>>, usize)>, | |
next: usize, | |
} | |
#[derive(Debug, Clone, PartialEq)] | |
pub enum GraphError { | |
NodeDead, | |
InvalidNode, | |
LockFailure, | |
} | |
#[derive(Debug, Clone)] | |
pub struct Graph<T>(Arc<Mutex<GraphInner<T>>>); | |
impl<T> Graph<T> { | |
pub fn new() -> Self { | |
let inner = GraphInner { | |
nodes: Vec::new(), | |
next: 0, | |
}; | |
Self(Arc::new(Mutex::new(inner))) | |
} | |
pub fn new_node(&self, value: T) -> Node<T> { | |
let mut lock = self.0.lock().unwrap(); | |
let next = lock.next; | |
let inner = NodeInner { | |
value, | |
neighbors: Vec::new(), | |
id: next, | |
}; | |
let node = Arc::new(Mutex::new(inner)); | |
if next < lock.nodes.len() { | |
let node_weak = Node(Arc::downgrade(&node)); | |
lock.nodes[next].0.replace(node.clone()); | |
lock.next = lock.nodes[next].1; | |
node_weak | |
} else { | |
let node_weak = Node(Arc::downgrade(&node)); | |
lock.nodes.push((Some(node.clone()), next + 1)); | |
lock.next += 1; | |
node_weak | |
} | |
} | |
pub fn remove_node(&self, node: &Node<T>) -> Result<(), GraphError> { | |
let mut lock = self.0.lock().or(Err(GraphError::LockFailure))?; | |
let rc = node.0.upgrade().ok_or(GraphError::NodeDead)?; | |
let id = rc.lock().unwrap().id; | |
if id < lock.nodes.len() { | |
let tar_node = lock.nodes[id].0.take(); | |
if tar_node.is_none() { | |
Err(GraphError::InvalidNode) | |
} else { | |
lock.nodes[id].1 = lock.next; | |
lock.next = id; | |
Ok(()) | |
} | |
} else { | |
Err(GraphError::InvalidNode) | |
} | |
} | |
} | |
#[derive(Debug, Clone)] | |
pub struct Node<T>(Weak<Mutex<NodeInner<T>>>); | |
impl<T> Node<T> { | |
pub fn push(&self, neighbor: &Node<T>) -> Result<(), GraphError> { | |
let rc = self.0.upgrade().ok_or(GraphError::NodeDead)?; | |
let mut lock = rc.lock().or(Err(GraphError::LockFailure))?; | |
lock.neighbors.push(Node(neighbor.0.clone())); | |
Ok(()) | |
} | |
pub fn read<V, F>(&self, f: F) -> Result<V, GraphError> where F: Fn(&T) -> V { | |
let rc = self.0.upgrade().ok_or(GraphError::NodeDead)?; | |
let lock = rc.lock().or(Err(GraphError::LockFailure))?; | |
let result = f(&lock.value); | |
Ok(result) | |
} | |
pub fn write(&self, val: T) -> Result<(), GraphError> { | |
let rc = self.0.upgrade().ok_or(GraphError::NodeDead)?; | |
let mut lock = rc.lock().or(Err(GraphError::LockFailure))?; | |
lock.value = val; | |
Ok(()) | |
} | |
pub fn modify<F>(&self, f: F) -> Result<(), GraphError> where F: Fn(&mut T) { | |
let rc = self.0.upgrade().ok_or(GraphError::NodeDead)?; | |
let mut lock = rc.lock().or(Err(GraphError::LockFailure))?; | |
f(&mut lock.value); | |
Ok(()) | |
} | |
pub fn get_neighbors(&self) -> Result<Vec<Node<T>>, GraphError> { | |
self.gc()?; | |
let rc = self.0.upgrade().ok_or(GraphError::NodeDead)?; | |
let lock = rc.lock().or(Err(GraphError::LockFailure))?; | |
let mut result = Vec::new(); | |
for n in lock.neighbors.iter().filter(|n| n.is_lived()) { | |
result.push(Node(n.0.clone())) | |
} | |
Ok(result) | |
} | |
fn gc(&self) -> Result<(), GraphError> { | |
let rc = self.0.upgrade().ok_or(GraphError::NodeDead)?; | |
let mut lock = rc.lock().or(Err(GraphError::LockFailure))?; | |
let mut cleaned = Vec::new(); | |
for n in lock.neighbors.iter().filter(|n| n.is_lived()) { | |
cleaned.push(Node(n.0.clone())) | |
} | |
lock.neighbors = cleaned; | |
Ok(()) | |
} | |
fn is_lived(&self) -> bool { | |
self.0.strong_count() > 0 | |
} | |
} | |
#[derive(Debug)] | |
struct NodeInner<T> { | |
value: T, | |
neighbors: Vec<Node<T>>, | |
id: usize, | |
} | |
#[cfg(test)] | |
mod tests { | |
use crate::{Graph, GraphError}; | |
#[test] | |
fn test_push_and_remove() { | |
let graph = Graph::new(); | |
let node1 = graph.new_node(1); | |
assert!(node1.is_lived()); | |
let node2 = graph.new_node(2); | |
assert!(node2.is_lived()); | |
let node3 = graph.new_node(3); | |
assert!(node3.is_lived()); | |
assert!(node1.push(&node2).is_ok()); | |
assert!(node2.push(&node3).is_ok()); | |
assert!(node3.push(&node1).is_ok()); | |
assert!(graph.remove_node(&node2).is_ok()); | |
assert!(graph.remove_node(&node2).is_err()); | |
assert!(node2.push(&node1).is_err()); | |
let node4 = graph.new_node(4); | |
let node5 = graph.new_node(5); | |
assert!(node4.is_lived()); | |
assert!(node5.is_lived()); | |
assert!(!node2.is_lived()); | |
assert!(node4.push(&node1).is_ok()); | |
assert!(node4.push(&node5).is_ok()); | |
assert!(node1.push(&node5).is_ok()); | |
assert_eq!(1, node1.get_neighbors().unwrap().len()); | |
assert_eq!(1, node3.get_neighbors().unwrap().len()); | |
assert_eq!(2, node4.get_neighbors().unwrap().len()); | |
assert_eq!(0, node5.get_neighbors().unwrap().len()); | |
} | |
#[test] | |
fn test_read_write() { | |
let graph = Graph::new(); | |
let node = graph.new_node("Hello".to_owned()); | |
let length = node.read(|value: &String| { | |
value.len() | |
}).unwrap(); | |
assert_eq!(5, length); | |
node.modify(|value: &mut String| { | |
*value = "World".to_owned(); | |
}).unwrap(); | |
node.read(|value| { | |
assert_eq!("World", value); | |
}).unwrap(); | |
node.write("Hello World!".to_owned()).unwrap(); | |
node.read(|value| { | |
assert_eq!("Hello World!", value); | |
}).unwrap(); | |
} | |
} |
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