workers: Pass a map of input filenames -> digest of file contents to workers so that they can cache and reuse state for unchanged inputs over multiple builds.

--
MOS_MIGRATED_REVID=107066408

2 files changed, 24 insertions, 0 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/worker/ExampleWorker.java b/src/test/java/com/google/devtools/build/lib/worker/ExampleWorker.java
index 78c03ff012..21c089c088 100644
--- a/src/test/java/com/google/devtools/build/lib/worker/ExampleWorker.java
+++ b/src/test/java/com/google/devtools/build/lib/worker/ExampleWorker.java
@@ -20,6 +20,7 @@ import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.worker.ExampleWorkerOptions.ExampleWorkOptions;
+import com.google.devtools.build.lib.worker.WorkerProtocol.Input;
 import com.google.devtools.build.lib.worker.WorkerProtocol.WorkRequest;
 import com.google.devtools.build.lib.worker.WorkerProtocol.WorkResponse;
 import com.google.devtools.common.options.OptionsParser;
@@ -30,7 +31,9 @@ import java.io.PrintStream;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.ArrayList;
+import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map.Entry;
 import java.util.UUID;
 
 /**
@@ -47,6 +50,9 @@ public class ExampleWorker {
   // If true, returns corrupt responses instead of correct protobufs.
   static boolean poisoned = false;
 
+  // Keep state across multiple builds.
+  static final LinkedHashMap<String, String> inputs = new LinkedHashMap<>();
+
   public static void main(String[] args) throws Exception {
     if (ImmutableSet.copyOf(args).contains("--persistent_worker")) {
       OptionsParser parser = OptionsParser.newOptionsParser(ExampleWorkerOptions.class);
@@ -73,6 +79,11 @@ public class ExampleWorker {
           break;
         }
 
+        inputs.clear();
+        for (Input input : request.getInputsList()) {
+          inputs.put(input.getPath(), input.getDigest().toStringUtf8());
+        }
+
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
         int exitCode = 0;
 
@@ -142,6 +153,12 @@ public class ExampleWorker {
     }
     outputs.add(residueStr);
 
+    if (options.printInputs) {
+      for (Entry<String, String> input : inputs.entrySet()) {
+        outputs.add("INPUT " + input.getKey() + " " + input.getValue());
+      }
+    }
+
     String outputStr = Joiner.on('\n').join(outputs);
     if (options.outputFile.isEmpty()) {
       System.out.println(outputStr);
diff --git a/src/test/java/com/google/devtools/build/lib/worker/ExampleWorkerOptions.java b/src/test/java/com/google/devtools/build/lib/worker/ExampleWorkerOptions.java
index 6a159ae512..7456e4b331 100644
--- a/src/test/java/com/google/devtools/build/lib/worker/ExampleWorkerOptions.java
+++ b/src/test/java/com/google/devtools/build/lib/worker/ExampleWorkerOptions.java
@@ -44,6 +44,13 @@ public class ExampleWorkerOptions extends OptionsBase {
       help = "Writes a counter that increases with each work unit processed into the output."
     )
     public boolean writeCounter;
+
+    @Option(
+      name = "print_inputs",
+      defaultValue = "false",
+      help = "Writes a list of input files and their digests."
+    )
+    public boolean printInputs;
   }
 
   @Option(name = "persistent_worker", defaultValue = "false")