Return SpawnResults using a List instead of a Set.

Currently we don't care about the list order of SpawnResults. However, we may care about the list order later. Also, if the equals() method for SpawnResults is ever changed then it may be problematic to return SpawnResults in a Set.

Aside: ActionResults use SpawnResults to calculate cumulative execution times for Actions, and may provide other metrics in future.

RELNOTES: None.
PiperOrigin-RevId: 176579460

1 files changed, 4 insertions, 5 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/exec/AbstractSpawnStrategy.java b/src/main/java/com/google/devtools/build/lib/exec/AbstractSpawnStrategy.java
index 93b58ff7e2..0f1cf259c0 100644
--- a/src/main/java/com/google/devtools/build/lib/exec/AbstractSpawnStrategy.java
+++ b/src/main/java/com/google/devtools/build/lib/exec/AbstractSpawnStrategy.java
@@ -16,7 +16,7 @@ package com.google.devtools.build.lib.exec;
 
 import com.google.common.base.Preconditions;
 import com.google.common.base.Predicates;
-import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 import com.google.common.eventbus.EventBus;
 import com.google.devtools.build.lib.actions.ActionExecutionContext;
@@ -44,7 +44,6 @@ import java.io.IOException;
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Set;
 import java.util.SortedMap;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
@@ -61,13 +60,13 @@ public abstract class AbstractSpawnStrategy implements SandboxedSpawnActionConte
   }
 
   @Override
-  public Set<SpawnResult> exec(Spawn spawn, ActionExecutionContext actionExecutionContext)
+  public List<SpawnResult> exec(Spawn spawn, ActionExecutionContext actionExecutionContext)
       throws ExecException, InterruptedException {
     return exec(spawn, actionExecutionContext, null);
   }
 
   @Override
-  public Set<SpawnResult> exec(
+  public List<SpawnResult> exec(
       Spawn spawn,
       ActionExecutionContext actionExecutionContext,
       AtomicReference<Class<? extends SpawnActionContext>> writeOutputFiles)
@@ -116,7 +115,7 @@ public abstract class AbstractSpawnStrategy implements SandboxedSpawnActionConte
               cwd);
       throw new SpawnExecException(message, spawnResult, /*forciblyRunRemotely=*/false);
     }
-    return ImmutableSet.of(spawnResult);
+    return ImmutableList.of(spawnResult);
   }
 
   private List<Path> listExistingOutputFiles(Spawn spawn, Path execRoot) {