From aeac483bacd2ed6070a611631f9ee127e79f8018 Mon Sep 17 00:00:00 2001
From: Christof Petig <christof.petig@arcor.de>
Date: Sat, 19 Mar 2022 15:51:07 +0100
Subject: [PATCH] parallel simulation of economies

---
 common/src/store.rs           | 10 ++++++++++
 world/src/sim2/mod.rs         | 12 +++++++-----
 world/src/site/economy/mod.rs |  2 ++
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/common/src/store.rs b/common/src/store.rs
index 7c03577d7d..99b2f37d36 100644
--- a/common/src/store.rs
+++ b/common/src/store.rs
@@ -1,3 +1,4 @@
+use rayon::prelude::*;
 use std::{
     cmp::{Eq, Ord, Ordering, PartialEq, PartialOrd},
     fmt, hash,
@@ -85,6 +86,15 @@ impl<T> Store<T> {
     }
 }
 
+impl<T: Send + Sync> Store<T> {
+    pub fn par_iter_mut(&mut self) -> impl ParallelIterator<Item = (Id<T>, &mut T)> {
+        self.items
+            .par_iter_mut()
+            .enumerate()
+            .map(|(idx, obj)| (Id(idx as u64, PhantomData), obj))
+    }
+}
+
 impl<T> Index<Id<T>> for Store<T> {
     type Output = T;
 
diff --git a/world/src/sim2/mod.rs b/world/src/sim2/mod.rs
index 7bcaa6b45c..1d8876564e 100644
--- a/world/src/sim2/mod.rs
+++ b/world/src/sim2/mod.rs
@@ -9,6 +9,7 @@ use crate::{
     },
     Index,
 };
+use rayon::prelude::*;
 use tracing::{debug, info};
 
 const TICK_PERIOD: f32 = 3.0 * DAYS_PER_MONTH; // 3 months
@@ -236,19 +237,20 @@ fn check_money(index: &mut Index) {
     );
 }
 
-pub fn tick(index: &mut Index, _world: &mut WorldSim, dt: f32, mut vc: vergleich::Context) {
+pub fn tick(index: &mut Index, _world: &mut WorldSim, dt: f32, _vc: vergleich::Context) {
     if INTER_SITE_TRADE {
         // move deliverables to recipient cities
         for (id, deliv) in index.trade.deliveries.drain() {
             index.sites.get_mut(id).economy.deliveries.extend(deliv);
         }
     }
-    for (site_id, site) in index.sites.iter_mut() {
+    index.sites.par_iter_mut().for_each(|(site_id, site)| {
         if site.do_economic_simulation() {
-            site.economy
-                .tick(site_id, dt, vc.context(&site_id.id().to_string()));
+            site.economy.tick(site_id, dt, vergleich::Context::dummy());
+            // helpful for debugging but not compatible with parallel execution
+            // vc.context(&site_id.id().to_string()));
         }
-    }
+    });
     if INTER_SITE_TRADE {
         // distribute orders (travelling merchants)
         for (_id, site) in index.sites.iter_mut() {
diff --git a/world/src/site/economy/mod.rs b/world/src/site/economy/mod.rs
index 0df0540658..f747a55944 100644
--- a/world/src/site/economy/mod.rs
+++ b/world/src/site/economy/mod.rs
@@ -43,6 +43,8 @@ pub mod vergleich {
         pub fn context(&mut self, _: &str) -> Context { Context {} }
 
         pub fn value(&mut self, _: &str, val: f32) -> f32 { val }
+
+        pub fn dummy() -> Self { Context {} }
     }
 }