From 921f4f715e3814fc2e22a4f6527ff62e066cc5da Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johannes=20K=C3=B6ster?= <johannes.koester@uni-due.de>
Date: Mon, 6 Sep 2021 21:59:08 +0200
Subject: [PATCH] perf: improve job selection performance in case of potential
 ambiguity that is resolved by comprehensive ruleorder statements. (#1147)

* perf: improve job selection performance in case of potential ambiguity that is resolved by comprehensive ruleorder statements.

* fmt

* improve order checking optimization after correct remarks from @dkuzminov.
---
 snakemake/dag.py | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/snakemake/dag.py b/snakemake/dag.py
index 44e4081d0..dbd6081fe 100755
--- a/snakemake/dag.py
+++ b/snakemake/dag.py
@@ -735,7 +735,18 @@ def update(
         exceptions = list()
         cycles = list()
 
-        for job in jobs:
+        # check if all potential producers are strictly ordered
+        jobs = sorted(jobs, reverse=True)
+        discarded_jobs = set()
+
+        def is_strictly_higher_ordered(pivot_job):
+            return all(
+                pivot_job > job
+                for job in jobs
+                if job is not pivot_job and job not in discarded_jobs
+            )
+
+        for i, job in enumerate(jobs):
             logger.dag_debug(dict(status="candidate", job=job))
             if file in job.input:
                 cycles.append(job)
@@ -753,9 +764,11 @@ def update(
                     progress=progress,
                     create_inventory=create_inventory,
                 )
-                # TODO this might fail if a rule discarded here is needed
-                # elsewhere
                 producers.append(job)
+                if is_strictly_higher_ordered(job):
+                    # All other jobs are either discarded or strictly less given
+                    # any defined ruleorder.
+                    break
             except (
                 MissingInputException,
                 CyclicGraphException,
@@ -763,6 +776,7 @@ def update(
                 WorkflowError,
             ) as ex:
                 exceptions.append(ex)
+                discarded_jobs.add(job)
             except RecursionError as e:
                 raise WorkflowError(
                     e,