Squashed 'components/zinit/' content from commit 1b76c06

git-subtree-dir: components/zinit
git-subtree-split: 1b76c062fe31d552d1b7b23484ce163995a81482

src/zinit/ord.rs

@@ -0,0 +1,37 @@
+use crate::zinit::types::ServiceTable;
+use std::collections::HashMap;
+use std::sync::Arc;
+use tokio::sync::RwLock;
+pub const DUMMY_ROOT: &str = "";
+pub struct ProcessDAG {
+    pub adj: HashMap<String, Vec<String>>,
+    pub indegree: HashMap<String, u32>,
+    /// number of services including the dummy root
+    pub count: u32,
+}
+pub async fn service_dependency_order(services: Arc<RwLock<ServiceTable>>) -> ProcessDAG {
+    let mut children: HashMap<String, Vec<String>> = HashMap::new();
+    let mut indegree: HashMap<String, u32> = HashMap::new();
+    let table = services.read().await;
+    for (name, service) in table.iter() {
+        let service = service.read().await;
+        for child in service.service.after.iter() {
+            children.entry(name.into()).or_default().push(child.into());
+            *indegree.entry(child.into()).or_insert(0) += 1;
+        }
+    }
+    let mut heads: Vec<String> = Vec::new();
+    for (name, _) in table.iter() {
+        if *indegree.get::<str>(name).unwrap_or(&0) == 0 {
+            heads.push(name.into());
+            // add edges from the dummy root to the heads
+            *indegree.entry(name.into()).or_insert(0) += 1;
+        }
+    }
+    children.insert(DUMMY_ROOT.to_string(), heads);
+    ProcessDAG {
+        adj: children,
+        indegree,
+        count: table.len() as u32 + 1,
+    }
+}