[RFC proxmox 1/5] resource-scheduling: move score_nodes_to_start_service to scheduler crate

[Daniel Kral <d.kral@proxmox.com>]

Signed-off-by: Daniel Kral <d.kral@proxmox.com>
---
 proxmox-resource-scheduling/src/lib.rs        |  2 +
 proxmox-resource-scheduling/src/pve_static.rs | 74 +---------------
 proxmox-resource-scheduling/src/scheduler.rs  | 86 +++++++++++++++++++
 3 files changed, 91 insertions(+), 71 deletions(-)
 create mode 100644 proxmox-resource-scheduling/src/scheduler.rs

diff --git a/proxmox-resource-scheduling/src/lib.rs b/proxmox-resource-scheduling/src/lib.rs
index 47980259..c73e7b1e 100644
--- a/proxmox-resource-scheduling/src/lib.rs
+++ b/proxmox-resource-scheduling/src/lib.rs
@@ -1,4 +1,6 @@
 #[macro_use]
 pub mod topsis;
 
+pub mod scheduler;
+
 pub mod pve_static;
diff --git a/proxmox-resource-scheduling/src/pve_static.rs b/proxmox-resource-scheduling/src/pve_static.rs
index b81086dd..184e615d 100644
--- a/proxmox-resource-scheduling/src/pve_static.rs
+++ b/proxmox-resource-scheduling/src/pve_static.rs
@@ -1,7 +1,7 @@
 use anyhow::Error;
 use serde::{Deserialize, Serialize};
 
-use crate::topsis;
+use crate::scheduler;
 
 #[derive(Serialize, Deserialize)]
 #[serde(rename_all = "kebab-case")]
@@ -35,7 +35,7 @@ impl AsRef<StaticNodeUsage> for StaticNodeUsage {
 
 /// Calculate new CPU usage in percent.
 /// `add` being `0.0` means "unlimited" and results in `max` being added.
-fn add_cpu_usage(old: f64, max: f64, add: f64) -> f64 {
+pub fn add_cpu_usage(old: f64, max: f64, add: f64) -> f64 {
     if add == 0.0 {
         old + max
     } else {
@@ -53,23 +53,6 @@ pub struct StaticServiceUsage {
     pub maxmem: usize,
 }
 
-criteria_struct! {
-    /// A given alternative.
-    struct PveTopsisAlternative {
-        #[criterion("average CPU", -1.0)]
-        average_cpu: f64,
-        #[criterion("highest CPU", -2.0)]
-        highest_cpu: f64,
-        #[criterion("average memory", -5.0)]
-        average_memory: f64,
-        #[criterion("highest memory", -10.0)]
-        highest_memory: f64,
-    }
-
-    const N_CRITERIA;
-    static PVE_HA_TOPSIS_CRITERIA;
-}
-
 /// Scores candidate `nodes` to start a `service` on. Scoring is done according to the static memory
 /// and CPU usages of the nodes as if the service would already be running on each.
 ///
@@ -79,56 +62,5 @@ pub fn score_nodes_to_start_service<T: AsRef<StaticNodeUsage>>(
     nodes: &[T],
     service: &StaticServiceUsage,
 ) -> Result<Vec<(String, f64)>, Error> {
-    let len = nodes.len();
-
-    let matrix = nodes
-        .iter()
-        .enumerate()
-        .map(|(target_index, _)| {
-            // Base values on percentages to allow comparing nodes with different stats.
-            let mut highest_cpu = 0.0;
-            let mut squares_cpu = 0.0;
-            let mut highest_mem = 0.0;
-            let mut squares_mem = 0.0;
-
-            for (index, node) in nodes.iter().enumerate() {
-                let node = node.as_ref();
-                let new_cpu = if index == target_index {
-                    add_cpu_usage(node.cpu, node.maxcpu as f64, service.maxcpu)
-                } else {
-                    node.cpu
-                } / (node.maxcpu as f64);
-                highest_cpu = f64::max(highest_cpu, new_cpu);
-                squares_cpu += new_cpu.powi(2);
-
-                let new_mem = if index == target_index {
-                    node.mem + service.maxmem
-                } else {
-                    node.mem
-                } as f64
-                    / node.maxmem as f64;
-                highest_mem = f64::max(highest_mem, new_mem);
-                squares_mem += new_mem.powi(2);
-            }
-
-            // Add 1.0 to avoid boosting tiny differences: e.g. 0.004 is twice as much as 0.002, but
-            // 1.004 is only slightly more than 1.002.
-            PveTopsisAlternative {
-                average_cpu: 1.0 + (squares_cpu / len as f64).sqrt(),
-                highest_cpu: 1.0 + highest_cpu,
-                average_memory: 1.0 + (squares_mem / len as f64).sqrt(),
-                highest_memory: 1.0 + highest_mem,
-            }
-            .into()
-        })
-        .collect::<Vec<_>>();
-
-    let scores =
-        topsis::score_alternatives(&topsis::Matrix::new(matrix)?, &PVE_HA_TOPSIS_CRITERIA)?;
-
-    Ok(scores
-        .into_iter()
-        .enumerate()
-        .map(|(n, score)| (nodes[n].as_ref().name.clone(), score))
-        .collect())
+    scheduler::score_nodes_to_start_service(nodes, service)
 }
diff --git a/proxmox-resource-scheduling/src/scheduler.rs b/proxmox-resource-scheduling/src/scheduler.rs
new file mode 100644
index 00000000..29353d84
--- /dev/null
+++ b/proxmox-resource-scheduling/src/scheduler.rs
@@ -0,0 +1,86 @@
+use anyhow::Error;
+
+use crate::{
+    pve_static::{add_cpu_usage, StaticNodeUsage, StaticServiceUsage},
+    topsis,
+};
+
+criteria_struct! {
+    /// A given alternative.
+    struct PveTopsisAlternative {
+        #[criterion("average CPU", -1.0)]
+        average_cpu: f64,
+        #[criterion("highest CPU", -2.0)]
+        highest_cpu: f64,
+        #[criterion("average memory", -5.0)]
+        average_memory: f64,
+        #[criterion("highest memory", -10.0)]
+        highest_memory: f64,
+    }
+
+    const N_CRITERIA;
+    static PVE_HA_TOPSIS_CRITERIA;
+}
+
+/// Scores candidate `nodes` to start a `service` on. Scoring is done according to the static memory
+/// and CPU usages of the nodes as if the service would already be running on each.
+///
+/// Returns a vector of (nodename, score) pairs. Scores are between 0.0 and 1.0 and a higher score
+/// is better.
+pub fn score_nodes_to_start_service<T: AsRef<StaticNodeUsage>>(
+    nodes: &[T],
+    service: &StaticServiceUsage,
+) -> Result<Vec<(String, f64)>, Error> {
+    let len = nodes.len();
+
+    let matrix = nodes
+        .iter()
+        .enumerate()
+        .map(|(target_index, _)| {
+            // Base values on percentages to allow comparing nodes with different stats.
+            let mut highest_cpu = 0.0;
+            let mut squares_cpu = 0.0;
+            let mut highest_mem = 0.0;
+            let mut squares_mem = 0.0;
+
+            for (index, node) in nodes.iter().enumerate() {
+                let node = node.as_ref();
+                let new_cpu = if index == target_index {
+                    add_cpu_usage(node.cpu, node.maxcpu as f64, service.maxcpu)
+                } else {
+                    node.cpu
+                } / (node.maxcpu as f64);
+                highest_cpu = f64::max(highest_cpu, new_cpu);
+                squares_cpu += new_cpu.powi(2);
+
+                let new_mem = if index == target_index {
+                    node.mem + service.maxmem
+                } else {
+                    node.mem
+                } as f64
+                    / node.maxmem as f64;
+                highest_mem = f64::max(highest_mem, new_mem);
+                squares_mem += new_mem.powi(2);
+            }
+
+            // Add 1.0 to avoid boosting tiny differences: e.g. 0.004 is twice as much as 0.002, but
+            // 1.004 is only slightly more than 1.002.
+            PveTopsisAlternative {
+                average_cpu: 1.0 + (squares_cpu / len as f64).sqrt(),
+                highest_cpu: 1.0 + highest_cpu,
+                average_memory: 1.0 + (squares_mem / len as f64).sqrt(),
+                highest_memory: 1.0 + highest_mem,
+            }
+            .into()
+        })
+        .collect::<Vec<_>>();
+
+    let scores =
+        topsis::score_alternatives(&topsis::Matrix::new(matrix)?, &PVE_HA_TOPSIS_CRITERIA)?;
+
+    Ok(scores
+        .into_iter()
+        .enumerate()
+        .map(|(n, score)| (nodes[n].as_ref().name.clone(), score))
+        .collect())
+}
-- 
2.47.3