Update ToolchainResolutionFunction to consider multiple available

execution platforms.

Part of #4442.

Change-Id: I6678d57f4aaadcb19032bf58820606242ba66a25
PiperOrigin-RevId: 184707708

1 files changed, 26 insertions, 9 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ToolchainResolutionValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/ToolchainResolutionValue.java
index 01909e6e8e..1f39059adf 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ToolchainResolutionValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ToolchainResolutionValue.java
@@ -15,14 +15,22 @@
 package com.google.devtools.build.lib.skyframe;
 
 import com.google.auto.value.AutoValue;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.platform.PlatformInfo;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.skyframe.SkyFunctionName;
 import com.google.devtools.build.skyframe.SkyKey;
 import com.google.devtools.build.skyframe.SkyValue;
+import java.util.List;
 
-/** A value which represents the selected toolchain for a specific target and execution platform. */
+/**
+ * A value which represents the map of potential execution platforms and resolved toolchains. This
+ * value only considers a single toolchain type, which allows for a Skyframe cache per toolchain
+ * type. Callers will need to consider all toolchain types that are required and merge the results
+ * together appropriately.
+ */
 @AutoValue
 public abstract class ToolchainResolutionValue implements SkyValue {
 
@@ -31,9 +39,9 @@ public abstract class ToolchainResolutionValue implements SkyValue {
       BuildConfiguration configuration,
       Label toolchainType,
       PlatformInfo targetPlatform,
-      PlatformInfo execPlatform) {
+      List<PlatformInfo> availableExecutionPlatforms) {
     return ToolchainResolutionKey.create(
-        configuration, toolchainType, targetPlatform, execPlatform);
+        configuration, toolchainType, targetPlatform, availableExecutionPlatforms);
   }
 
   /** {@link SkyKey} implementation used for {@link ToolchainResolutionFunction}. */
@@ -50,21 +58,30 @@ public abstract class ToolchainResolutionValue implements SkyValue {
 
     public abstract PlatformInfo targetPlatform();
 
-    public abstract PlatformInfo execPlatform();
+    public abstract ImmutableList<PlatformInfo> availableExecutionPlatforms();
 
     public static ToolchainResolutionKey create(
         BuildConfiguration configuration,
         Label toolchainType,
         PlatformInfo targetPlatform,
-        PlatformInfo execPlatform) {
+        List<PlatformInfo> availableExecutionPlatforms) {
       return new AutoValue_ToolchainResolutionValue_ToolchainResolutionKey(
-          configuration, toolchainType, targetPlatform, execPlatform);
+          configuration,
+          toolchainType,
+          targetPlatform,
+          ImmutableList.copyOf(availableExecutionPlatforms));
     }
   }
 
-  public static ToolchainResolutionValue create(Label toolchainLabel) {
-    return new AutoValue_ToolchainResolutionValue(toolchainLabel);
+  public static ToolchainResolutionValue create(
+      ImmutableMap<PlatformInfo, Label> availableToolchainLabels) {
+    return new AutoValue_ToolchainResolutionValue(availableToolchainLabels);
   }
 
-  public abstract Label toolchainLabel();
+  /**
+   * Returns the resolved set of toolchain labels (as {@link Label}) for the requested toolchain
+   * type, keyed by the execution platforms (as {@link PlatformInfo}). Ordering is not preserved, if
+   * the caller cares about the order of platforms it must take care of that directly.
+   */
+  public abstract ImmutableMap<PlatformInfo, Label> availableToolchainLabels();
 }