Add builder for WorkRequestHandler.

Preparation for adding another parameter for cancellation.

RELNOTES: None.
PiperOrigin-RevId: 371139211

src/java_tools/buildjar/java/com/google/devtools/build/buildjar/BazelJavaBuilder.java

@@ -25,6 +25,7 @@
 import com.google.devtools.build.buildjar.javac.plugins.errorprone.ErrorPronePlugin;
 import com.google.devtools.build.lib.worker.ProtoWorkerMessageProcessor;
 import com.google.devtools.build.lib.worker.WorkRequestHandler;
+import com.google.devtools.build.lib.worker.WorkRequestHandler.WorkRequestHandlerBuilder;
 import java.io.IOException;
 import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
@@ -44,11 +45,12 @@ public static void main(String[] args) {
  BazelJavaBuilder builder = new BazelJavaBuilder();
  if (args.length == 1 && args[0].equals("--persistent_worker")) {
  WorkRequestHandler workerHandler =
- new WorkRequestHandler(
- builder::parseAndBuild,
- System.err,
- new ProtoWorkerMessageProcessor(System.in, System.out),
- Duration.ofSeconds(10));
+ new WorkRequestHandlerBuilder(
+ builder::parseAndBuild,
+ System.err,
+ new ProtoWorkerMessageProcessor(System.in, System.out))
+ .setCpuUsageBeforeGc(Duration.ofSeconds(10))
+ .build();
  try {
  workerHandler.processRequests();
  } catch (IOException e) {

src/main/java/com/google/devtools/build/lib/worker/WorkRequestHandler.java

@@ -91,8 +91,10 @@ public WorkRequestHandler(
  * @param messageProcessor Object responsible for parsing {@code WorkRequest}s from the server and
  * writing {@code WorkResponses} to the server.
  * @param cpuUsageBeforeGc The minimum amount of CPU time between explicit garbage collection
- * calls.
+ * calls. Pass Duration.ZERO to not do explicit garbage collection.
+ * @deprecated Use WorkRequestHandlerBuilder instead.
  */
+ @Deprecated()
  public WorkRequestHandler(
  BiFunction<List<String>, PrintWriter, Integer> callback,
  PrintStream stderr,
@@ -104,6 +106,48 @@ public WorkRequestHandler(
  this.gcScheduler = new CpuTimeBasedGcScheduler(cpuUsageBeforeGc);
  }
 
+ /** Builder class for WorkRequestHandler. Required parameters are passed to the constructor. */
+ public static class WorkRequestHandlerBuilder {
+ private final BiFunction<List<String>, PrintWriter, Integer> callback;
+ private final PrintStream stderr;
+ private final WorkerMessageProcessor messageProcessor;
+ private Duration cpuUsageBeforeGc = Duration.ZERO;
+
+ /**
+ * Creates a {@code WorkRequestHandlerBuilder}.
+ *
+ * @param callback Callback method for executing a single WorkRequest in a thread. The first
+ * argument to {@code callback} is the set of command-line arguments, the second is where
+ * all error messages and other user-oriented messages should be written to. The callback
+ * must return an exit code indicating success (zero) or failure (nonzero).
+ * @param stderr Stream that log messages should be written to, typically the process' stderr.
+ * @param messageProcessor Object responsible for parsing {@code WorkRequest}s from the server
+ * and writing {@code WorkResponses} to the server.
+ */
+ public WorkRequestHandlerBuilder(
+ BiFunction<List<String>, PrintWriter, Integer> callback,
+ PrintStream stderr,
+ WorkerMessageProcessor messageProcessor) {
+ this.callback = callback;
+ this.stderr = stderr;
+ this.messageProcessor = messageProcessor;
+ }
+
+ /**
+ * Sets the minimum amount of CPU time between explicit garbage collection calls. Pass
+ * Duration.ZERO to not do explicit garbage collection (the default).
+ */
+ public WorkRequestHandlerBuilder setCpuUsageBeforeGc(Duration cpuUsageBeforeGc) {
+ this.cpuUsageBeforeGc = cpuUsageBeforeGc;
+ return this;
+ }
+
+ /** Returns a WorkRequestHandler instance with the values in this Builder. */
+ public WorkRequestHandler build() {
+ return new WorkRequestHandler(callback, stderr, messageProcessor, cpuUsageBeforeGc);
+ }
+ }
+
  /**
  * Runs an infinite loop of reading {@link WorkRequest} from {@code in}, running the callback,
  * then writing the corresponding {@link WorkResponse} to {@code out}. If there is an error