Add a mechanism for build event protocol events to upload files

This should be a no-op, mostly replacing PathConverter with
BuildEventArtifactUploader, since none of the implementations perform any
upload yet.

PiperOrigin-RevId: 200685325

26 files changed, 557 insertions, 237 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionExecutedEvent.java b/src/main/java/com/google/devtools/build/lib/actions/ActionExecutedEvent.java
index 52ec1096fc..a4fa28be5e 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionExecutedEvent.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionExecutedEvent.java
@@ -17,6 +17,7 @@ package com.google.devtools.build.lib.actions;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.buildeventstream.BuildEvent;
 import com.google.devtools.build.lib.buildeventstream.BuildEventContext;
 import com.google.devtools.build.lib.buildeventstream.BuildEventId;
@@ -117,6 +118,21 @@ public class ActionExecutedEvent implements BuildEventWithConfiguration, Progres
   }
 
   @Override
+  public ImmutableSet<Path> referencedLocalFiles() {
+    ImmutableSet.Builder<Path> artifacts = ImmutableSet.builder();
+    if (stdout != null) {
+      artifacts.add(stdout);
+    }
+    if (stderr != null) {
+      artifacts.add(stderr);
+    }
+    if (exception == null) {
+      artifacts.add(action.getPrimaryOutput().getPath());
+    }
+    return artifacts.build();
+  }
+
+  @Override
   public BuildEventStreamProtos.BuildEvent asStreamProto(BuildEventContext converters) {
     PathConverter pathConverter = converters.pathConverter();
     BuildEventStreamProtos.ActionExecuted.Builder actionBuilder =
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/TargetCompleteEvent.java b/src/main/java/com/google/devtools/build/lib/analysis/TargetCompleteEvent.java
index 7473de21b6..adb71f4f9d 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/TargetCompleteEvent.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/TargetCompleteEvent.java
@@ -278,6 +278,19 @@ public final class TargetCompleteEvent
   }
 
   @Override
+  public ImmutableSet<Path> referencedLocalFiles() {
+    ImmutableSet.Builder<Path> builder = ImmutableSet.builder();
+    for (ArtifactsInOutputGroup group : outputs) {
+      if (group.areImportant()) {
+        for (Artifact artifact : group.getArtifacts()) {
+          builder.add(artifact.getPath());
+        }
+      }
+    }
+    return builder.build();
+  }
+
+  @Override
   public BuildEventStreamProtos.BuildEvent asStreamProto(BuildEventContext converters) {
     BuildEventStreamProtos.TargetComplete.Builder builder =
         BuildEventStreamProtos.TargetComplete.newBuilder();
diff --git a/src/main/java/com/google/devtools/build/lib/authandtls/GoogleAuthUtils.java b/src/main/java/com/google/devtools/build/lib/authandtls/GoogleAuthUtils.java
index 28682aef5d..21b6588b1d 100644
--- a/src/main/java/com/google/devtools/build/lib/authandtls/GoogleAuthUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/authandtls/GoogleAuthUtils.java
@@ -113,12 +113,15 @@ public final class GoogleAuthUtils {
   }
 
   /**
-   * Create a new {@link Credentials} object.
+   * Create a new {@link Credentials} object, or {@code null} if no options are provided.
    *
    * @throws IOException in case the credentials can't be constructed.
    */
-  public static Credentials newCredentials(AuthAndTLSOptions options) throws IOException {
-    if (options.googleCredentials != null) {
+  @Nullable
+  public static Credentials newCredentials(@Nullable AuthAndTLSOptions options) throws IOException {
+    if (options == null) {
+      return null;
+    } else if (options.googleCredentials != null) {
       // Credentials from file
       try (InputStream authFile = new FileInputStream(options.googleCredentials)) {
         return newCredentials(authFile, options.googleAuthScopes);
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceModule.java b/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceModule.java
index 80c5599620..115808a66a 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceModule.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceModule.java
@@ -20,14 +20,16 @@ import static com.google.devtools.build.lib.buildeventservice.BuildEventServiceT
 import static java.lang.String.format;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.authandtls.AuthAndTLSOptions;
 import com.google.devtools.build.lib.buildeventservice.client.BuildEventServiceClient;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploader;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploaderMap;
 import com.google.devtools.build.lib.buildeventstream.BuildEventProtocolOptions;
 import com.google.devtools.build.lib.buildeventstream.BuildEventTransport;
-import com.google.devtools.build.lib.buildeventstream.PathConverter;
 import com.google.devtools.build.lib.buildeventstream.transports.BuildEventStreamOptions;
 import com.google.devtools.build.lib.buildeventstream.transports.BuildEventTransportFactory;
 import com.google.devtools.build.lib.clock.Clock;
@@ -72,8 +74,7 @@ public abstract class BuildEventServiceModule<T extends BuildEventServiceOptions
   }
 
   @Override
-  public void beforeCommand(CommandEnvironment commandEnvironment)
-      throws AbruptExitException {
+  public void beforeCommand(CommandEnvironment commandEnvironment) {
     // Reset to null in case afterCommand was not called.
     this.outErr = null;
     if (!whitelistedCommands().contains(commandEnvironment.getCommandName())) {
@@ -87,7 +88,7 @@ public abstract class BuildEventServiceModule<T extends BuildEventServiceOptions
             commandEnvironment.getReporter(),
             commandEnvironment.getBlazeModuleEnvironment(),
             commandEnvironment.getRuntime().getClock(),
-            commandEnvironment.getRuntime().getPathToUriConverter(),
+            commandEnvironment.getRuntime().getBuildEventArtifactUploaders(),
             commandEnvironment.getReporter(),
             commandEnvironment.getBuildRequestId().toString(),
             commandEnvironment.getCommandId().toString(),
@@ -129,9 +130,7 @@ public abstract class BuildEventServiceModule<T extends BuildEventServiceOptions
     this.outErr = null;
   }
 
-  /**
-   * Returns {@code null} if no stream could be created.
-   */
+  /** Returns {@code null} if no stream could be created. */
   @Nullable
   @VisibleForTesting
   BuildEventStreamer tryCreateStreamer(
@@ -140,11 +139,13 @@ public abstract class BuildEventServiceModule<T extends BuildEventServiceOptions
       EventHandler commandLineReporter,
       ModuleEnvironment moduleEnvironment,
       Clock clock,
-      PathConverter pathConverter,
+      BuildEventArtifactUploaderMap artifactUploaders,
       Reporter reporter,
       String buildRequestId,
       String invocationId,
       String commandName) {
+    Preconditions.checkNotNull(artifactUploaders);
+
     try {
       T besOptions =
           checkNotNull(
@@ -172,18 +173,20 @@ public abstract class BuildEventServiceModule<T extends BuildEventServiceOptions
                 moduleEnvironment,
                 clock,
                 protocolOptions,
-                pathConverter,
+                artifactUploaders,
                 commandLineReporter,
                 startupOptionsProvider);
       } catch (Exception e) {
         commandLineReporter.handle(Event.error(format(UPLOAD_FAILED_MESSAGE, e.getMessage())));
-        moduleEnvironment.exit(new AbruptExitException(
-            "Failed while creating BuildEventTransport", ExitCode.PUBLISH_ERROR));
+        moduleEnvironment.exit(
+            new AbruptExitException(
+                "Failed while creating BuildEventTransport", ExitCode.PUBLISH_ERROR));
         return null;
       }
 
       ImmutableSet<BuildEventTransport> bepTransports =
-          BuildEventTransportFactory.createFromOptions(bepOptions, protocolOptions, pathConverter);
+          BuildEventTransportFactory.createFromOptions(
+              bepOptions, protocolOptions, artifactUploaders, moduleEnvironment::exit);
 
       ImmutableSet.Builder<BuildEventTransport> transportsBuilder =
           ImmutableSet.<BuildEventTransport>builder().addAll(bepTransports);
@@ -213,7 +216,7 @@ public abstract class BuildEventServiceModule<T extends BuildEventServiceOptions
       ModuleEnvironment moduleEnvironment,
       Clock clock,
       BuildEventProtocolOptions protocolOptions,
-      PathConverter pathConverter,
+      BuildEventArtifactUploaderMap artifactUploaders,
       EventHandler commandLineReporter,
       OptionsProvider startupOptionsProvider)
       throws IOException, OptionsParsingException {
@@ -242,9 +245,13 @@ public abstract class BuildEventServiceModule<T extends BuildEventServiceOptions
                     besOptions.besBackend, buildRequestId, invocationId)));
       }
 
+      BuildEventServiceClient client = createBesClient(besOptions, authTlsOptions);
+      BuildEventArtifactUploader artifactUploader =
+          artifactUploaders.select(protocolOptions.buildEventUploadStrategy);
+
       BuildEventTransport besTransport =
           new BuildEventServiceTransport(
-              createBesClient(besOptions, authTlsOptions),
+              client,
               besOptions.besTimeout,
               besOptions.besLifecycleEvents,
               buildRequestId,
@@ -253,11 +260,11 @@ public abstract class BuildEventServiceModule<T extends BuildEventServiceOptions
               moduleEnvironment,
               clock,
               protocolOptions,
-              pathConverter,
               commandLineReporter,
               besOptions.projectId,
               keywords(besOptions, startupOptionsProvider),
-              besResultsUrl);
+              besResultsUrl,
+              artifactUploader);
       logger.fine("BuildEventServiceTransport was created successfully");
       return besTransport;
     }
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceProtoUtil.java b/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceProtoUtil.java
index 217fcbd419..dc6172cd08 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceProtoUtil.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceProtoUtil.java
@@ -107,6 +107,11 @@ public final class BuildEventServiceProtoUtil {
     return streamSequenceNumber.getAndIncrement();
   }
 
+  /** Creates a PublishBuildToolEventStreamRequest from a packed bazel event. */
+  public PublishBuildToolEventStreamRequest bazelEvent(Any packedEvent, int sequenceNumber) {
+    return bazelEvent(sequenceNumber, packedEvent);
+  }
+
   @VisibleForTesting
   public PublishBuildToolEventStreamRequest bazelEvent(int sequenceNumber, Any packedEvent) {
     return publishBuildToolEventStreamRequest(
@@ -114,7 +119,6 @@ public final class BuildEventServiceProtoUtil {
         com.google.devtools.build.v1.BuildEvent.newBuilder().setBazelEvent(packedEvent));
   }
 
-  @VisibleForTesting
   public PublishBuildToolEventStreamRequest streamFinished(int sequenceNumber) {
     return publishBuildToolEventStreamRequest(
         sequenceNumber,
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceTransport.java b/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceTransport.java
index 37355cc6f6..acf5686671 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceTransport.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceTransport.java
@@ -27,6 +27,7 @@ import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableSet;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.ListeningExecutorService;
 import com.google.common.util.concurrent.SettableFuture;
@@ -34,6 +35,7 @@ import com.google.devtools.build.lib.buildeventservice.client.BuildEventServiceC
 import com.google.devtools.build.lib.buildeventstream.ArtifactGroupNamer;
 import com.google.devtools.build.lib.buildeventstream.BuildCompletingEvent;
 import com.google.devtools.build.lib.buildeventstream.BuildEvent;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploader;
 import com.google.devtools.build.lib.buildeventstream.BuildEventContext;
 import com.google.devtools.build.lib.buildeventstream.BuildEventProtocolOptions;
 import com.google.devtools.build.lib.buildeventstream.BuildEventStreamProtos;
@@ -48,12 +50,14 @@ import com.google.devtools.build.lib.util.AbruptExitException;
 import com.google.devtools.build.lib.util.ExitCode;
 import com.google.devtools.build.lib.util.JavaSleeper;
 import com.google.devtools.build.lib.util.Sleeper;
+import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.v1.BuildStatus.Result;
 import com.google.devtools.build.v1.PublishBuildToolEventStreamRequest;
 import com.google.devtools.build.v1.PublishBuildToolEventStreamResponse;
 import com.google.devtools.build.v1.PublishLifecycleEventRequest;
 import com.google.protobuf.Any;
 import io.grpc.Status;
+import java.io.IOException;
 import java.time.Duration;
 import java.util.Deque;
 import java.util.Set;
@@ -95,7 +99,7 @@ public class BuildEventServiceTransport implements BuildEventTransport {
   private final ModuleEnvironment moduleEnvironment;
   private final EventHandler commandLineReporter;
   private final BuildEventProtocolOptions protocolOptions;
-  private final PathConverter pathConverter;
+  private final BuildEventArtifactUploader artifactUploader;
   private final Sleeper sleeper;
   /** Contains all pendingAck events that might be retried in case of failures. */
   private ConcurrentLinkedDeque<InternalOrderedBuildEvent> pendingAck;
@@ -131,11 +135,11 @@ public class BuildEventServiceTransport implements BuildEventTransport {
       ModuleEnvironment moduleEnvironment,
       Clock clock,
       BuildEventProtocolOptions protocolOptions,
-      PathConverter pathConverter,
       EventHandler commandLineReporter,
       @Nullable String projectId,
       Set<String> keywords,
-      @Nullable String besResultsUrl) {
+      @Nullable String besResultsUrl,
+      BuildEventArtifactUploader artifactUploader) {
     this(
         besClient,
         uploadTimeout,
@@ -146,12 +150,12 @@ public class BuildEventServiceTransport implements BuildEventTransport {
         moduleEnvironment,
         clock,
         protocolOptions,
-        pathConverter,
         commandLineReporter,
         projectId,
         keywords,
-        new JavaSleeper(),
-        besResultsUrl);
+        besResultsUrl,
+        artifactUploader,
+        new JavaSleeper());
   }
 
   @VisibleForTesting
@@ -165,12 +169,12 @@ public class BuildEventServiceTransport implements BuildEventTransport {
       ModuleEnvironment moduleEnvironment,
       Clock clock,
       BuildEventProtocolOptions protocolOptions,
-      PathConverter pathConverter,
       EventHandler commandLineReporter,
       @Nullable String projectId,
       Set<String> keywords,
-      Sleeper sleeper,
-      @Nullable String besResultsUrl) {
+      @Nullable String besResultsUrl,
+      BuildEventArtifactUploader artifactUploader,
+      Sleeper sleeper) {
     this.besClient = besClient;
     this.besProtoUtil =
         new BuildEventServiceProtoUtil(
@@ -187,9 +191,9 @@ public class BuildEventServiceTransport implements BuildEventTransport {
     // TODO(buchgr): Fix it.
     this.uploaderExecutorService = listeningDecorator(Executors.newFixedThreadPool(2));
     this.protocolOptions = protocolOptions;
-    this.pathConverter = pathConverter;
     this.invocationResult = UNKNOWN_STATUS;
     this.uploadTimeout = uploadTimeout;
+    this.artifactUploader = artifactUploader;
     this.sleeper = sleeper;
     this.besResultsUrl = besResultsUrl;
   }
@@ -480,6 +484,27 @@ public class BuildEventServiceTransport implements BuildEventTransport {
       do {
         orderedBuildEvent = pendingSend.pollFirst(STREAMING_RPC_POLL_IN_SECS, TimeUnit.SECONDS);
         if (orderedBuildEvent != null) {
+          final PathConverter pathConverter;
+          try {
+            pathConverter = artifactUploader.upload(orderedBuildEvent.referencedLocalFiles());
+          } catch (IOException e) {
+            logger.log(
+                Level.WARNING,
+                String.format(
+                    "Aborting publishBuildToolEventStream RPC because of a failure to "
+                        + "upload referenced artifacts: %s",
+                    e.getMessage()),
+                e);
+            besClient.abortStream(Status.INTERNAL.augmentDescription(e.getMessage()));
+            throw e;
+          } catch (InterruptedException e) {
+            // By convention the interrupted flag should have been cleared,
+            // but just to be sure clear it.
+            Thread.interrupted();
+            String additionalDetails = "Uploading referenced artifacts";
+            besClient.abortStream(Status.CANCELLED.augmentDescription(additionalDetails));
+            throw e;
+          }
           pendingAck.add(orderedBuildEvent);
           besClient.sendOverStream(orderedBuildEvent.serialize(pathConverter));
         }
@@ -621,6 +646,8 @@ public class BuildEventServiceTransport implements BuildEventTransport {
 
     int getSequenceNumber();
 
+    Set<Path> referencedLocalFiles();
+
     PublishBuildToolEventStreamRequest serialize(PathConverter pathConverter);
   }
 
@@ -647,6 +674,11 @@ public class BuildEventServiceTransport implements BuildEventTransport {
     }
 
     @Override
+    public Set<Path> referencedLocalFiles() {
+      return event.referencedLocalFiles();
+    }
+
+    @Override
     public PublishBuildToolEventStreamRequest serialize(PathConverter pathConverter) {
       BuildEventStreamProtos.BuildEvent eventProto =
           event.asStreamProto(
@@ -666,7 +698,7 @@ public class BuildEventServiceTransport implements BuildEventTransport {
                   return protocolOptions;
                 }
               });
-      return besProtoUtil.bazelEvent(sequenceNumber, Any.pack(eventProto));
+      return besProtoUtil.bazelEvent(Any.pack(eventProto), sequenceNumber);
     }
   }
 
@@ -688,6 +720,11 @@ public class BuildEventServiceTransport implements BuildEventTransport {
     }
 
     @Override
+    public Set<Path> referencedLocalFiles() {
+      return ImmutableSet.of();
+    }
+
+    @Override
     public PublishBuildToolEventStreamRequest serialize(PathConverter pathConverter) {
       return besProtoUtil.streamFinished(sequenceNumber);
     }
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEvent.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEvent.java
index de4cfb8c88..6d6900687c 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEvent.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEvent.java
@@ -14,7 +14,10 @@
 
 package com.google.devtools.build.lib.buildeventstream;
 
+import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.events.ExtendedEventHandler;
+import com.google.devtools.build.lib.vfs.Path;
+import java.util.Set;
 
 /**
  * Interface for objects that can be posted on the public event stream.
@@ -23,11 +26,29 @@ import com.google.devtools.build.lib.events.ExtendedEventHandler;
  * pass-through of events, as well as proper chaining of events.
  */
 public interface BuildEvent extends ChainableEvent, ExtendedEventHandler.Postable {
+
+  /**
+   * Returns a list of files that are referenced in the protobuf representation returned by {@link
+   * #asStreamProto(BuildEventContext)}.
+   *
+   * <p>This method is different from {@code EventReportingArtifacts#reportedArtifacts()} in that it
+   * only returns files directly referenced in the protobuf returned by {@link
+   * #asStreamProto(BuildEventContext)}.
+   *
+   * <p>Note the consistency requirement - you must not attempt to pass Path objects to the
+   * {@link PathConverter} unless you have returned the Path object here.
+   */
+  // TODO(ulfjack): Consider moving the upload call to the BuildEventContext and returning a map
+  // from Path to URI, rather than a callback.
+  default Set<Path> referencedLocalFiles() {
+    return ImmutableSet.of();
+  }
+
   /**
    * Provide a binary representation of the event.
    *
    * <p>Provide a presentation of the event according to the specified binary format, as appropriate
    * protocol buffer.
    */
-  BuildEventStreamProtos.BuildEvent asStreamProto(BuildEventContext converters);
+  BuildEventStreamProtos.BuildEvent asStreamProto(BuildEventContext context);
 }
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventArtifactUploader.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventArtifactUploader.java
new file mode 100644
index 0000000000..7b7ffb15ab
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventArtifactUploader.java
@@ -0,0 +1,38 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package com.google.devtools.build.lib.buildeventstream;
+
+import com.google.devtools.build.lib.buildeventstream.PathConverter.FileUriPathConverter;
+import com.google.devtools.build.lib.vfs.Path;
+import java.io.IOException;
+import java.util.Set;
+
+/** Uploads artifacts referenced by the Build Event Protocol (BEP). */
+public interface BuildEventArtifactUploader {
+  public static final BuildEventArtifactUploader LOCAL_FILES_UPLOADER =
+      new BuildEventArtifactUploader() {
+    @Override
+    public PathConverter upload(Set<Path> files) {
+      return new FileUriPathConverter();
+    }
+  };
+
+  /**
+   * Uploads a set of files referenced by the protobuf representation of a {@link BuildEvent}.
+   *
+   * <p>Returns a {@link PathConverter} that must provide a name for each uploaded file as it should
+   * appear in the BEP.
+   */
+  PathConverter upload(Set<Path> files) throws IOException, InterruptedException;
+}
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventArtifactUploaderMap.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventArtifactUploaderMap.java
new file mode 100644
index 0000000000..8987def882
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventArtifactUploaderMap.java
@@ -0,0 +1,59 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package com.google.devtools.build.lib.buildeventstream;
+
+import com.google.common.collect.ImmutableMap;
+import java.util.SortedMap;
+import java.util.TreeMap;
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
+
+/** Selects between multiple available upload strategies. */
+@ThreadSafe
+public class BuildEventArtifactUploaderMap {
+  private final ImmutableMap<String, BuildEventArtifactUploader> uploaders;
+
+  private BuildEventArtifactUploaderMap(
+      ImmutableMap<String, BuildEventArtifactUploader> uploaders) {
+    this.uploaders = uploaders;
+  }
+
+  public BuildEventArtifactUploader select(@Nullable String name) {
+    if (name == null) {
+      // TODO(b/110235226): We currently choose the strategy with alphabetically first strategy,
+      // which happens to be backwards-compatible; we need to set
+      // experimental_build_event_upload_strategy to appropriate default values instead, and then
+      // make it an error to pass null.
+      return uploaders.values().iterator().next();
+    }
+    return uploaders.getOrDefault(name, BuildEventArtifactUploader.LOCAL_FILES_UPLOADER);
+  }
+
+  /** Builder class for {@link BuildEventArtifactUploaderMap}. */
+  public static class Builder {
+    private final SortedMap<String, BuildEventArtifactUploader> uploaders = new TreeMap<>();
+
+    public Builder() {
+    }
+
+    public Builder add(String name, BuildEventArtifactUploader uploader) {
+      uploaders.put(name, uploader);
+      return this;
+    }
+
+    public BuildEventArtifactUploaderMap build() {
+      return new BuildEventArtifactUploaderMap(ImmutableMap.copyOf(uploaders));
+    }
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventProtocolOptions.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventProtocolOptions.java
index e22d1669ef..4f31f75eaa 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventProtocolOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventProtocolOptions.java
@@ -28,7 +28,16 @@ public class BuildEventProtocolOptions extends OptionsBase {
     documentationCategory = OptionDocumentationCategory.LOGGING,
     effectTags = {OptionEffectTag.AFFECTS_OUTPUTS},
     help = "Use this to suppress generation of the legacy important_outputs field in the "
-        + "TargetComplete event"
+        + "TargetComplete event."
   )
   public boolean legacyImportantOutputs;
+
+  @Option(
+    name = "experimental_build_event_upload_strategy",
+    defaultValue = "null",
+    documentationCategory = OptionDocumentationCategory.LOGGING,
+    effectTags = {OptionEffectTag.AFFECTS_OUTPUTS},
+    help = "Selects how to upload artifacts referenced in the build event protocol."
+  )
+  public String buildEventUploadStrategy;
 }
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventTransport.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventTransport.java
index 9b930b9ecd..9d61c1c4e3 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventTransport.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventTransport.java
@@ -26,7 +26,6 @@ import javax.annotation.concurrent.ThreadSafe;
  */
 @ThreadSafe
 public interface BuildEventTransport {
-
   /**
    * The name of this transport as can be displayed to a user.
    */
@@ -39,16 +38,14 @@ public interface BuildEventTransport {
    * <p>In case the transport is in error, this method still needs to be able to accept build
    * events. It may choose to ignore them, though.
    *
-   * <p>This method should not throw any exceptions.
-   *
    * @param event the event to sendBuildEvent.
    */
   void sendBuildEvent(BuildEvent event, ArtifactGroupNamer namer);
 
   /**
-   * Initiates a close. Callers may listen to the returned future to be notified when the close
-   * is complete i.e. wait for all build events to be sent. The future does not contain any
-   * information about possible transport errors.
+   * Initiates a close. Callers may listen to the returned future to be notified when the close is
+   * complete i.e. wait for all build events to be sent. The future may contain any information
+   * about possible transport errors.
    *
    * <p>This method might be called multiple times without any effect after the first call.
    *
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildToolLogs.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildToolLogs.java
index fe68043eb0..c4eee48b28 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildToolLogs.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildToolLogs.java
@@ -14,6 +14,7 @@
 package com.google.devtools.build.lib.buildeventstream;
 
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.util.Pair;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.protobuf.ByteString;
@@ -41,6 +42,15 @@ public class BuildToolLogs implements BuildEventWithOrderConstraint {
   }
 
   @Override
+  public ImmutableSet<Path> referencedLocalFiles() {
+    ImmutableSet.Builder<Path> artifacts = ImmutableSet.builder();
+    for (Pair<String, Path> logFile : logFiles) {
+      artifacts.add(logFile.getSecond());
+    }
+    return artifacts.build();
+  }
+
+  @Override
   public BuildEventStreamProtos.BuildEvent asStreamProto(BuildEventContext converters) {
     BuildEventStreamProtos.BuildToolLogs.Builder toolLogs =
         BuildEventStreamProtos.BuildToolLogs.newBuilder();
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/PathConverter.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/PathConverter.java
index e230d36953..a1aaf31d40 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventstream/PathConverter.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/PathConverter.java
@@ -13,15 +13,75 @@
 // limitations under the License.
 package com.google.devtools.build.lib.buildeventstream;
 
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
 import com.google.devtools.build.lib.vfs.Path;
+import java.net.URI;
+import java.net.URISyntaxException;
 
 /**
  * Interface for conversion of paths to URIs.
  */
 public interface PathConverter {
+  /** An implementation that throws on every call to {@link #apply(Path)}. */
+  public static final PathConverter NO_CONVERSION = new PathConverter() {
+    @Override
+    public String apply(Path path) {
+      throw new IllegalStateException(
+          String.format(
+              "Can't convert '%s', as it has not been"
+                  + "declared as a referenced artifact of a build event",
+              path.getPathString()));
+    }
+  };
+
+  /** A {@link PathConverter} that returns a path formatted as a URI with a {@code file} scheme. */
+  // TODO(ulfjack): Make this a static final field.
+  final class FileUriPathConverter implements PathConverter {
+    @Override
+    public String apply(Path path) {
+      Preconditions.checkNotNull(path);
+      return pathToUriString(path.getPathString());
+    }
+
+    /**
+     * Returns the path encoded as an {@link URI}.
+     *
+     * <p>This concrete implementation returns URIs with "file" as the scheme. For Example: - On
+     * Unix the path "/tmp/foo bar.txt" will be encoded as "file:///tmp/foo%20bar.txt". - On Windows
+     * the path "C:\Temp\Foo Bar.txt" will be encoded as "file:///C:/Temp/Foo%20Bar.txt"
+     *
+     * <p>Implementors extending this class for special filesystems will likely need to override
+     * this method.
+     */
+    @VisibleForTesting
+    static String pathToUriString(String path) {
+      if (!path.startsWith("/")) {
+        // On Windows URI's need to start with a '/'. i.e. C:\Foo\Bar would be file:///C:/Foo/Bar
+        path = "/" + path;
+      }
+      try {
+        return new URI(
+                "file",
+                // Needs to be "" instead of null, so that toString() will append "//" after the
+                // scheme.
+                // We need this for backwards compatibility reasons as some consumers of the BEP are
+                // broken.
+                "",
+                path,
+                null,
+                null)
+            .toString();
+      } catch (URISyntaxException e) {
+        throw new IllegalStateException(e);
+      }
+    }
+  }
+
   /**
-   * Return the URI corresponding to the given path, if the path can be converted to a URI by this
-   * path converter; return {@link null} otherwise.
+   * Return the URI corresponding to the given path.
+   *
+   * <p>This method must not return {@code null}.
    */
   String apply(Path path);
 }
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/BUILD b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/BUILD
index 7d8fe5709a..117d18cf19 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/BUILD
@@ -10,7 +10,9 @@ java_library(
     name = "transports",
     srcs = glob(["*.java"]),
     deps = [
+        "//src/main/java/com/google/devtools/build/lib:exitcode-external",
         "//src/main/java/com/google/devtools/build/lib:io",
+        "//src/main/java/com/google/devtools/build/lib:util",
         "//src/main/java/com/google/devtools/build/lib/buildeventstream",
         "//src/main/java/com/google/devtools/build/lib/buildeventstream/proto:build_event_stream_java_proto",
         "//src/main/java/com/google/devtools/build/lib/vfs",
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/BinaryFormatFileTransport.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/BinaryFormatFileTransport.java
index 71e4fd878a..2f1d15c25a 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/BinaryFormatFileTransport.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/BinaryFormatFileTransport.java
@@ -14,30 +14,28 @@
 
 package com.google.devtools.build.lib.buildeventstream.transports;
 
-import static com.google.common.base.Preconditions.checkNotNull;
-
 import com.google.devtools.build.lib.buildeventstream.ArtifactGroupNamer;
 import com.google.devtools.build.lib.buildeventstream.BuildEvent;
-import com.google.devtools.build.lib.buildeventstream.BuildEventContext;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploader;
 import com.google.devtools.build.lib.buildeventstream.BuildEventProtocolOptions;
+import com.google.devtools.build.lib.buildeventstream.BuildEventStreamProtos;
 import com.google.devtools.build.lib.buildeventstream.BuildEventTransport;
-import com.google.devtools.build.lib.buildeventstream.PathConverter;
+import com.google.devtools.build.lib.util.AbruptExitException;
 import java.io.IOException;
+import java.util.function.Consumer;
 
 /**
  * A simple {@link BuildEventTransport} that writes a varint delimited binary representation of
  * {@link BuildEvent} protocol buffers to a file.
  */
 public final class BinaryFormatFileTransport extends FileTransport {
-  private final BuildEventProtocolOptions options;
-  private final PathConverter pathConverter;
-
   BinaryFormatFileTransport(
-      String path, BuildEventProtocolOptions options, PathConverter pathConverter)
-          throws IOException {
-    super(path);
-    this.options = options;
-    this.pathConverter = pathConverter;
+      String path,
+      BuildEventProtocolOptions options,
+      BuildEventArtifactUploader uploader,
+      Consumer<AbruptExitException> exitFunc)
+      throws IOException {
+    super(path, options, uploader, exitFunc);
   }
 
   @Override
@@ -47,24 +45,10 @@ public final class BinaryFormatFileTransport extends FileTransport {
 
   @Override
   public synchronized void sendBuildEvent(BuildEvent event, final ArtifactGroupNamer namer) {
-    checkNotNull(event);
-    BuildEventContext converters =
-        new BuildEventContext() {
-          @Override
-          public PathConverter pathConverter() {
-            return pathConverter;
-          }
-
-          @Override
-          public ArtifactGroupNamer artifactGroupNamer() {
-            return namer;
-          }
-
-          @Override
-          public BuildEventProtocolOptions getOptions() {
-            return options;
-          }
-        };
-    write(event.asStreamProto(converters));
+    BuildEventStreamProtos.BuildEvent protoEvent = asStreamProto(event, namer);
+    if (protoEvent == null) {
+      return;
+    }
+    write(protoEvent);
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/BuildEventTransportFactory.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/BuildEventTransportFactory.java
index 0cc84b0f74..eef7583451 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/BuildEventTransportFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/BuildEventTransportFactory.java
@@ -17,13 +17,13 @@ package com.google.devtools.build.lib.buildeventstream.transports;
 import static com.google.common.base.Strings.isNullOrEmpty;
 
 import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploader;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploaderMap;
 import com.google.devtools.build.lib.buildeventstream.BuildEventProtocolOptions;
 import com.google.devtools.build.lib.buildeventstream.BuildEventTransport;
-import com.google.devtools.build.lib.buildeventstream.PathConverter;
-import com.google.devtools.build.lib.vfs.Path;
+import com.google.devtools.build.lib.util.AbruptExitException;
 import java.io.IOException;
-import java.net.URI;
-import java.net.URISyntaxException;
+import java.util.function.Consumer;
 
 /** Factory used to create a Set of BuildEventTransports from BuildEventStreamOptions. */
 public enum BuildEventTransportFactory {
@@ -37,11 +37,16 @@ public enum BuildEventTransportFactory {
     protected BuildEventTransport create(
         BuildEventStreamOptions options,
         BuildEventProtocolOptions protocolOptions,
-        PathConverter pathConverter) throws IOException {
+        BuildEventArtifactUploader uploader,
+        Consumer<AbruptExitException> exitFunc)
+        throws IOException {
       return new TextFormatFileTransport(
-          options.getBuildEventTextFile(),
-          protocolOptions,
-          options.getBuildEventTextFilePathConversion() ? pathConverter : new NullPathConverter());
+          options.getBuildEventTextFile(), protocolOptions, uploader, exitFunc);
+    }
+
+    @Override
+    protected boolean usePathConverter(BuildEventStreamOptions options) {
+      return options.getBuildEventTextFilePathConversion();
     }
   },
 
@@ -55,13 +60,16 @@ public enum BuildEventTransportFactory {
     protected BuildEventTransport create(
         BuildEventStreamOptions options,
         BuildEventProtocolOptions protocolOptions,
-        PathConverter pathConverter) throws IOException {
+        BuildEventArtifactUploader uploader,
+        Consumer<AbruptExitException> exitFunc)
+        throws IOException {
       return new BinaryFormatFileTransport(
-          options.getBuildEventBinaryFile(),
-          protocolOptions,
-          options.getBuildEventBinaryFilePathConversion()
-              ? pathConverter
-              : new NullPathConverter());
+          options.getBuildEventBinaryFile(), protocolOptions, uploader, exitFunc);
+    }
+
+    @Override
+    protected boolean usePathConverter(BuildEventStreamOptions options) {
+      return options.getBuildEventBinaryFilePathConversion();
     }
   },
 
@@ -75,11 +83,16 @@ public enum BuildEventTransportFactory {
     protected BuildEventTransport create(
         BuildEventStreamOptions options,
         BuildEventProtocolOptions protocolOptions,
-        PathConverter pathConverter) throws IOException {
+        BuildEventArtifactUploader uploader,
+        Consumer<AbruptExitException> exitFunc)
+        throws IOException {
       return new JsonFormatFileTransport(
-          options.getBuildEventJsonFile(),
-          protocolOptions,
-          options.getBuildEventJsonFilePathConversion() ? pathConverter : new NullPathConverter());
+          options.getBuildEventJsonFile(), protocolOptions, uploader, exitFunc);
+    }
+
+    @Override
+    protected boolean usePathConverter(BuildEventStreamOptions options) {
+      return options.getBuildEventJsonFilePathConversion();
     }
   };
 
@@ -94,13 +107,17 @@ public enum BuildEventTransportFactory {
   public static ImmutableSet<BuildEventTransport> createFromOptions(
       BuildEventStreamOptions options,
       BuildEventProtocolOptions protocolOptions,
-      PathConverter pathConverter)
-          throws IOException {
+      BuildEventArtifactUploaderMap artifactUploaders,
+      Consumer<AbruptExitException> exitFunc)
+      throws IOException {
     ImmutableSet.Builder<BuildEventTransport> buildEventTransportsBuilder = ImmutableSet.builder();
     for (BuildEventTransportFactory transportFactory : BuildEventTransportFactory.values()) {
       if (transportFactory.enabled(options)) {
+        BuildEventArtifactUploader uploader = transportFactory.usePathConverter(options)
+            ? artifactUploaders.select(protocolOptions.buildEventUploadStrategy)
+            : BuildEventArtifactUploader.LOCAL_FILES_UPLOADER;
         buildEventTransportsBuilder.add(
-            transportFactory.create(options, protocolOptions, pathConverter));
+            transportFactory.create(options, protocolOptions, uploader, exitFunc));
       }
     }
     return buildEventTransportsBuilder.build();
@@ -113,47 +130,9 @@ public enum BuildEventTransportFactory {
   protected abstract BuildEventTransport create(
       BuildEventStreamOptions options,
       BuildEventProtocolOptions protocolOptions,
-      PathConverter pathConverter)
-          throws IOException;
+      BuildEventArtifactUploader uploader,
+      Consumer<AbruptExitException> exitFunc)
+      throws IOException;
 
-  private static class NullPathConverter implements PathConverter {
-    @Override
-    public String apply(Path path) {
-      return pathToUriString(path.getPathString());
-    }
-  }
-
-  /**
-   * Returns the path encoded as an {@link URI}.
-   *
-   * <p>This concrete implementation returns URIs with "file" as the scheme. For Example: - On Unix
-   * the path "/tmp/foo bar.txt" will be encoded as "file:///tmp/foo%20bar.txt". - On Windows the
-   * path "C:\Temp\Foo Bar.txt" will be encoded as "file:///C:/Temp/Foo%20Bar.txt"
-   *
-   * <p>Implementors extending this class for special filesystems will likely need to override this
-   * method.
-   *
-   * @throws URISyntaxException if the URI cannot be constructed.
-   */
-  static String pathToUriString(String path) {
-    if (!path.startsWith("/")) {
-      // On Windows URI's need to start with a '/'. i.e. C:\Foo\Bar would be file:///C:/Foo/Bar
-      path = "/" + path;
-    }
-    try {
-      return new URI(
-              "file",
-              // Needs to be "" instead of null, so that toString() will append "//" after the
-              // scheme.
-              // We need this for backwards compatibility reasons as some consumers of the BEP are
-              // broken.
-              "",
-              path,
-              null,
-              null)
-          .toString();
-    } catch (URISyntaxException e) {
-      throw new IllegalStateException(e);
-    }
-  }
+  protected abstract boolean usePathConverter(BuildEventStreamOptions options);
 }
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/FileTransport.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/FileTransport.java
index a2d1164bb2..540a7e84cd 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/FileTransport.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/FileTransport.java
@@ -14,16 +14,32 @@
 
 package com.google.devtools.build.lib.buildeventstream.transports;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Throwables;
 import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.MoreExecutors;
+import com.google.devtools.build.lib.buildeventstream.ArtifactGroupNamer;
+import com.google.devtools.build.lib.buildeventstream.BuildEvent;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploader;
+import com.google.devtools.build.lib.buildeventstream.BuildEventContext;
+import com.google.devtools.build.lib.buildeventstream.BuildEventProtocolOptions;
+import com.google.devtools.build.lib.buildeventstream.BuildEventStreamProtos;
 import com.google.devtools.build.lib.buildeventstream.BuildEventTransport;
+import com.google.devtools.build.lib.buildeventstream.PathConverter;
+import com.google.devtools.build.lib.util.AbruptExitException;
+import com.google.devtools.build.lib.util.ExitCode;
 import com.google.devtools.build.lib.util.io.AsynchronousFileOutputStream;
+import com.google.devtools.build.lib.vfs.Path;
 import com.google.protobuf.Message;
 import java.io.IOException;
+import java.util.Set;
+import java.util.function.Consumer;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import javax.annotation.Nullable;
 
 /**
  * Non-blocking file transport.
@@ -35,10 +51,23 @@ import java.util.logging.Logger;
 abstract class FileTransport implements BuildEventTransport {
   private static final Logger logger = Logger.getLogger(FileTransport.class.getName());
 
+  private final BuildEventProtocolOptions options;
+  private final BuildEventArtifactUploader uploader;
+  private final Consumer<AbruptExitException> exitFunc;
+  private boolean errored;
+
   @VisibleForTesting
   final AsynchronousFileOutputStream out;
 
-  FileTransport(String path) throws IOException {
+  FileTransport(
+      String path,
+      BuildEventProtocolOptions options,
+      BuildEventArtifactUploader uploader,
+      Consumer<AbruptExitException> exitFunc)
+          throws IOException {
+    this.uploader = uploader;
+    this.options = options;
+    this.exitFunc = exitFunc;
     out = new AsynchronousFileOutputStream(path);
   }
 
@@ -60,7 +89,6 @@ abstract class FileTransport implements BuildEventTransport {
     }
   }
 
-
   @Override
   public synchronized ListenableFuture<Void> close() {
     return Futures.catching(
@@ -77,4 +105,63 @@ abstract class FileTransport implements BuildEventTransport {
   public void closeNow() {
     out.closeNow();
   }
+
+  /**
+   * Converts the given event into a proto object; this may trigger uploading of referenced files as
+   * a side effect. May return {@code null} if there was an interrupt. This method is not
+   * thread-safe.
+   */
+  @Nullable
+  protected BuildEventStreamProtos.BuildEvent asStreamProto(
+      BuildEvent event, ArtifactGroupNamer namer) {
+    checkNotNull(event);
+    PathConverter pathConverter = uploadReferencedFiles(event.referencedLocalFiles());
+    if (pathConverter == null) {
+      return null;
+    }
+
+    BuildEventContext context =
+        new BuildEventContext() {
+          @Override
+          public PathConverter pathConverter() {
+            return pathConverter;
+          }
+
+          @Override
+          public ArtifactGroupNamer artifactGroupNamer() {
+            return namer;
+          }
+
+          @Override
+          public BuildEventProtocolOptions getOptions() {
+            return options;
+          }
+        };
+    return event.asStreamProto(context);
+  }
+
+  /**
+   * Returns a {@link PathConverter} for the uploaded files, or {@code null} when the uploaded
+   * failed.
+   */
+  private @Nullable PathConverter uploadReferencedFiles(Set<Path> artifacts) {
+    checkNotNull(artifacts);
+
+    if (errored) {
+      return null;
+    }
+    try {
+      return uploader.upload(artifacts);
+    } catch (IOException e) {
+      errored = true;
+      exitFunc.accept(
+          new AbruptExitException(
+              Throwables.getStackTraceAsString(e), ExitCode.PUBLISH_ERROR, e));
+    } catch (InterruptedException e) {
+      errored = true;
+      exitFunc.accept(new AbruptExitException(ExitCode.INTERRUPTED, e));
+      Thread.currentThread().interrupt();
+    }
+    return null;
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/JsonFormatFileTransport.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/JsonFormatFileTransport.java
index 3d51c4f632..33b296143e 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/JsonFormatFileTransport.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/JsonFormatFileTransport.java
@@ -16,28 +16,28 @@ package com.google.devtools.build.lib.buildeventstream.transports;
 
 import com.google.devtools.build.lib.buildeventstream.ArtifactGroupNamer;
 import com.google.devtools.build.lib.buildeventstream.BuildEvent;
-import com.google.devtools.build.lib.buildeventstream.BuildEventContext;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploader;
 import com.google.devtools.build.lib.buildeventstream.BuildEventProtocolOptions;
+import com.google.devtools.build.lib.buildeventstream.BuildEventStreamProtos;
 import com.google.devtools.build.lib.buildeventstream.BuildEventTransport;
-import com.google.devtools.build.lib.buildeventstream.PathConverter;
+import com.google.devtools.build.lib.util.AbruptExitException;
 import com.google.protobuf.InvalidProtocolBufferException;
 import com.google.protobuf.util.JsonFormat;
 import java.io.IOException;
+import java.util.function.Consumer;
 
 /**
  * A simple {@link BuildEventTransport} that writes the JSON representation of the protocol-buffer
  * representation of the events to a file.
  */
 public final class JsonFormatFileTransport extends FileTransport {
-  private final BuildEventProtocolOptions options;
-  private final PathConverter pathConverter;
-
   JsonFormatFileTransport(
-      String path, BuildEventProtocolOptions options, PathConverter pathConverter)
-          throws IOException {
-    super(path);
-    this.options = options;
-    this.pathConverter = pathConverter;
+      String path,
+      BuildEventProtocolOptions options,
+      BuildEventArtifactUploader uploader,
+      Consumer<AbruptExitException> exitFunc)
+      throws IOException {
+    super(path, options, uploader, exitFunc);
   }
 
   @Override
@@ -47,30 +47,14 @@ public final class JsonFormatFileTransport extends FileTransport {
 
   @Override
   public synchronized void sendBuildEvent(BuildEvent event, final ArtifactGroupNamer namer) {
-    BuildEventContext converters =
-        new BuildEventContext() {
-          @Override
-          public PathConverter pathConverter() {
-            return pathConverter;
-          }
-
-          @Override
-          public ArtifactGroupNamer artifactGroupNamer() {
-            return namer;
-          }
-
-          @Override
-          public BuildEventProtocolOptions getOptions() {
-            return options;
-          }
-        };
+    BuildEventStreamProtos.BuildEvent protoEvent = asStreamProto(event, namer);
+    if (protoEvent == null) {
+      return;
+    }
     String protoJsonRepresentation;
     try {
       protoJsonRepresentation =
-          JsonFormat.printer()
-                  .omittingInsignificantWhitespace()
-                  .print(event.asStreamProto(converters))
-              + "\n";
+          JsonFormat.printer().omittingInsignificantWhitespace().print(protoEvent) + "\n";
     } catch (InvalidProtocolBufferException e) {
       // We don't expect any unknown Any fields in our protocol buffer. Nevertheless, handle
       // the exception gracefully and, at least, return valid JSON with an id field.
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/TextFormatFileTransport.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/TextFormatFileTransport.java
index 2735712bfb..af1364f3bf 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/TextFormatFileTransport.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/TextFormatFileTransport.java
@@ -16,12 +16,14 @@ package com.google.devtools.build.lib.buildeventstream.transports;
 
 import com.google.devtools.build.lib.buildeventstream.ArtifactGroupNamer;
 import com.google.devtools.build.lib.buildeventstream.BuildEvent;
-import com.google.devtools.build.lib.buildeventstream.BuildEventContext;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploader;
 import com.google.devtools.build.lib.buildeventstream.BuildEventProtocolOptions;
+import com.google.devtools.build.lib.buildeventstream.BuildEventStreamProtos;
 import com.google.devtools.build.lib.buildeventstream.BuildEventTransport;
-import com.google.devtools.build.lib.buildeventstream.PathConverter;
+import com.google.devtools.build.lib.util.AbruptExitException;
 import com.google.protobuf.TextFormat;
 import java.io.IOException;
+import java.util.function.Consumer;
 
 /**
  * A simple {@link BuildEventTransport} that writes the text representation of the protocol-buffer
@@ -30,15 +32,13 @@ import java.io.IOException;
  * <p>This class is used for debugging.
  */
 public final class TextFormatFileTransport extends FileTransport {
-  private final BuildEventProtocolOptions options;
-  private final PathConverter pathConverter;
-
   TextFormatFileTransport(
-      String path, BuildEventProtocolOptions options, PathConverter pathConverter)
-          throws IOException {
-    super(path);
-    this.options = options;
-    this.pathConverter = pathConverter;
+      String path,
+      BuildEventProtocolOptions options,
+      BuildEventArtifactUploader uploader,
+      Consumer<AbruptExitException> exitFunc)
+      throws IOException {
+    super(path, options, uploader, exitFunc);
   }
 
   @Override
@@ -48,24 +48,11 @@ public final class TextFormatFileTransport extends FileTransport {
 
   @Override
   public synchronized void sendBuildEvent(BuildEvent event, final ArtifactGroupNamer namer) {
-    BuildEventContext converters =
-        new BuildEventContext() {
-          @Override
-          public PathConverter pathConverter() {
-            return pathConverter;
-          }
-
-          @Override
-          public ArtifactGroupNamer artifactGroupNamer() {
-            return namer;
-          }
-
-          @Override
-          public BuildEventProtocolOptions getOptions() {
-            return options;
-          }
-        };
-    String protoTextRepresentation = TextFormat.printToString(event.asStreamProto(converters));
+    BuildEventStreamProtos.BuildEvent protoEvent = asStreamProto(event, namer);
+    if (protoEvent == null) {
+      return;
+    }
+    String protoTextRepresentation = TextFormat.printToString(protoEvent);
     write("event {\n" + protoTextRepresentation + "}\n\n");
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/exec/TestAttempt.java b/src/main/java/com/google/devtools/build/lib/exec/TestAttempt.java
index deec19e3f3..5d2c94a540 100644
--- a/src/main/java/com/google/devtools/build/lib/exec/TestAttempt.java
+++ b/src/main/java/com/google/devtools/build/lib/exec/TestAttempt.java
@@ -17,6 +17,7 @@ package com.google.devtools.build.lib.exec;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.test.TestRunnerAction;
 import com.google.devtools.build.lib.buildeventstream.BuildEventContext;
@@ -188,6 +189,15 @@ public class TestAttempt implements BuildEventWithOrderConstraint {
   }
 
   @Override
+  public ImmutableSet<Path> referencedLocalFiles() {
+    ImmutableSet.Builder<Path> artifacts = ImmutableSet.builder();
+    for (Pair<String, Path> file : files) {
+      artifacts.add(file.getSecond());
+    }
+    return artifacts.build();
+  }
+
+  @Override
   public BuildEventStreamProtos.BuildEvent asStreamProto(BuildEventContext converters) {
     return GenericBuildEvent.protoChaining(this).setTestResult(asTestResult(converters)).build();
   }
diff --git a/src/main/java/com/google/devtools/build/lib/remote/RemoteModule.java b/src/main/java/com/google/devtools/build/lib/remote/RemoteModule.java
index 9201c94858..d5b0db5965 100644
--- a/src/main/java/com/google/devtools/build/lib/remote/RemoteModule.java
+++ b/src/main/java/com/google/devtools/build/lib/remote/RemoteModule.java
@@ -20,6 +20,7 @@ import com.google.common.util.concurrent.ListeningScheduledExecutorService;
 import com.google.common.util.concurrent.MoreExecutors;
 import com.google.devtools.build.lib.authandtls.AuthAndTLSOptions;
 import com.google.devtools.build.lib.authandtls.GoogleAuthUtils;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploader;
 import com.google.devtools.build.lib.buildeventstream.PathConverter;
 import com.google.devtools.build.lib.buildtool.BuildRequest;
 import com.google.devtools.build.lib.events.Event;
@@ -42,6 +43,7 @@ import com.google.devtools.remoteexecution.v1test.Digest;
 import io.grpc.Channel;
 import io.grpc.ClientInterceptors;
 import java.io.IOException;
+import java.util.Set;
 import java.util.concurrent.Executors;
 import java.util.logging.Logger;
 
@@ -60,11 +62,12 @@ public final class RemoteModule extends BlazeModule {
     // the PathConverter.
     RemoteOptions options;
     DigestUtil digestUtil;
+    PathConverter fallbackConverter = new FileUriPathConverter();
 
     @Override
     public String apply(Path path) {
       if (options == null || digestUtil == null || !remoteEnabled(options)) {
-        return null;
+        return fallbackConverter.apply(path);
       }
       String server = options.remoteCache;
       String remoteInstanceName = options.remoteInstanceName;
@@ -84,7 +87,7 @@ public final class RemoteModule extends BlazeModule {
                 digest.getSizeBytes());
       } catch (IOException e) {
         // TODO(ulfjack): Don't fail silently!
-        return null;
+        return fallbackConverter.apply(path);
       }
     }
   }
@@ -95,9 +98,14 @@ public final class RemoteModule extends BlazeModule {
   private RemoteActionContextProvider actionContextProvider;
 
   @Override
-  public void serverInit(OptionsProvider startupOptions, ServerBuilder builder)
-      throws AbruptExitException {
-    builder.addPathToUriConverter(converter);
+  public void serverInit(OptionsProvider startupOptions, ServerBuilder builder) {
+    builder.addBuildEventArtifactUploader(new BuildEventArtifactUploader() {
+      @Override
+      public PathConverter upload(Set<Path> files) {
+        // TODO(ulfjack): Actually hook up upload here.
+        return converter;
+      }
+    }, "remote");
   }
 
   @Override
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java b/src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java
index d4591a46b2..44e9f61e39 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java
@@ -31,7 +31,7 @@ import com.google.devtools.build.lib.analysis.ServerDirectories;
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.ConfigurationFragmentFactory;
 import com.google.devtools.build.lib.analysis.test.CoverageReportActionFactory;
-import com.google.devtools.build.lib.buildeventstream.PathConverter;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploaderMap;
 import com.google.devtools.build.lib.clock.BlazeClock;
 import com.google.devtools.build.lib.clock.Clock;
 import com.google.devtools.build.lib.events.Event;
@@ -153,7 +153,7 @@ public final class BlazeRuntime {
   private final String defaultsPackageContent;
   private final SubscriberExceptionHandler eventBusExceptionHandler;
   private final String productName;
-  private final PathConverter pathToUriConverter;
+  private final BuildEventArtifactUploaderMap buildEventArtifactUploaders;
   private final ActionKeyContext actionKeyContext;
 
   // Workspace state (currently exactly one workspace per server)
@@ -178,7 +178,7 @@ public final class BlazeRuntime {
       InvocationPolicy moduleInvocationPolicy,
       Iterable<BlazeCommand> commands,
       String productName,
-      PathConverter pathToUriConverter) {
+      BuildEventArtifactUploaderMap buildEventArtifactUploaders) {
     // Server state
     this.fileSystem = fileSystem;
     this.blazeModules = blazeModules;
@@ -205,7 +205,7 @@ public final class BlazeRuntime {
     CommandNameCache.CommandNameCacheInstance.INSTANCE.setCommandNameCache(
         new CommandNameCacheImpl(getCommandMap()));
     this.productName = productName;
-    this.pathToUriConverter = pathToUriConverter;
+    this.buildEventArtifactUploaders = buildEventArtifactUploaders;
   }
 
   public BlazeWorkspace initWorkspace(BlazeDirectories directories, BinTools binTools)
@@ -1261,8 +1261,8 @@ public final class BlazeRuntime {
     return productName;
   }
 
-  public PathConverter getPathToUriConverter() {
-    return pathToUriConverter;
+  public BuildEventArtifactUploaderMap getBuildEventArtifactUploaders() {
+    return buildEventArtifactUploaders;
   }
 
   /**
@@ -1369,7 +1369,7 @@ public final class BlazeRuntime {
           serverBuilder.getInvocationPolicy(),
           serverBuilder.getCommands(),
           productName,
-          serverBuilder.getPathToUriConverter());
+          serverBuilder.getBuildEventArtifactUploaderMap());
     }
 
     public Builder setProductName(String productName) {
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/NamedArtifactGroup.java b/src/main/java/com/google/devtools/build/lib/runtime/NamedArtifactGroup.java
index b990c15c7b..431b4276ad 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/NamedArtifactGroup.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/NamedArtifactGroup.java
@@ -25,6 +25,7 @@ import com.google.devtools.build.lib.buildeventstream.BuildEventStreamProtos;
 import com.google.devtools.build.lib.buildeventstream.GenericBuildEvent;
 import com.google.devtools.build.lib.buildeventstream.PathConverter;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetView;
+import com.google.devtools.build.lib.vfs.Path;
 import java.util.Collection;
 
 /**
@@ -52,6 +53,19 @@ class NamedArtifactGroup implements BuildEvent {
   }
 
   @Override
+  public ImmutableSet<Path> referencedLocalFiles() {
+    // This has to be consistent with the code below.
+    ImmutableSet.Builder<Path> artifacts = ImmutableSet.builder();
+    for (Artifact artifact : view.directs()) {
+      if (artifact.isMiddlemanArtifact()) {
+        continue;
+      }
+      artifacts.add(artifact.getPath());
+    }
+    return artifacts.build();
+  }
+
+  @Override
   public BuildEventStreamProtos.BuildEvent asStreamProto(BuildEventContext converters) {
     PathConverter pathConverter = converters.pathConverter();
     ArtifactGroupNamer namer = converters.artifactGroupNamer();
@@ -59,6 +73,7 @@ class NamedArtifactGroup implements BuildEvent {
     BuildEventStreamProtos.NamedSetOfFiles.Builder builder =
         BuildEventStreamProtos.NamedSetOfFiles.newBuilder();
     for (Artifact artifact : view.directs()) {
+      // We never want to report middleman artifacts. They are for internal use only.
       if (artifact.isMiddlemanArtifact()) {
         continue;
       }
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/ServerBuilder.java b/src/main/java/com/google/devtools/build/lib/runtime/ServerBuilder.java
index b8dc2eb7ef..73bb27e67a 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/ServerBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/ServerBuilder.java
@@ -18,7 +18,8 @@ import com.google.common.base.Function;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
-import com.google.devtools.build.lib.buildeventstream.PathConverter;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploader;
+import com.google.devtools.build.lib.buildeventstream.BuildEventArtifactUploaderMap;
 import com.google.devtools.build.lib.packages.AttributeContainer;
 import com.google.devtools.build.lib.packages.PackageFactory;
 import com.google.devtools.build.lib.packages.RuleClass;
@@ -28,7 +29,6 @@ import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryFunctio
 import com.google.devtools.build.lib.query2.output.OutputFormatter;
 import com.google.devtools.build.lib.runtime.commands.InfoItem;
 import com.google.devtools.build.lib.runtime.proto.InvocationPolicyOuterClass.InvocationPolicy;
-import com.google.devtools.build.lib.vfs.Path;
 
 /**
  * Builder class to create a {@link BlazeRuntime} instance. This class is part of the module API,
@@ -45,8 +45,8 @@ public final class ServerBuilder {
       ImmutableList.builder();
   private final ImmutableList.Builder<PackageFactory.EnvironmentExtension> environmentExtensions =
       ImmutableList.builder();
-  private final ImmutableList.Builder<PathConverter> pathToUriConverters
-      = ImmutableList.builder();
+  private final BuildEventArtifactUploaderMap.Builder buildEventArtifactUploaders =
+      new BuildEventArtifactUploaderMap.Builder();
 
   @VisibleForTesting
   public ServerBuilder() {}
@@ -87,25 +87,8 @@ public final class ServerBuilder {
     return commands.build();
   }
 
-  /**
-   * Return the derived total converter from Paths to URIs. It returns the answer of the first
-   * registered converter that can convert the given path, if any. If no registered converter can
-   * convert the given path, the "file" URI scheme is used.
-   */
-  public PathConverter getPathToUriConverter() {
-    final ImmutableList<PathConverter> converters = this.pathToUriConverters.build();
-    return new PathConverter(){
-      @Override
-      public String apply(Path path) {
-        for (PathConverter converter : converters) {
-          String value = converter.apply(path);
-          if (value != null) {
-            return value;
-          }
-        }
-        return "file://" + path.getPathString();
-      }
-    };
+  public BuildEventArtifactUploaderMap getBuildEventArtifactUploaderMap() {
+    return buildEventArtifactUploaders.build();
   }
 
   /**
@@ -195,11 +178,9 @@ public final class ServerBuilder {
     return this;
   }
 
-  /**
-   * Register a new {@link PathConverter}. Contervers are tried in the order they are registered.
-   */
-  public ServerBuilder addPathToUriConverter(PathConverter converter) {
-    this.pathToUriConverters.add(converter);
+  public ServerBuilder addBuildEventArtifactUploader(
+      BuildEventArtifactUploader uploader, String name) {
+    buildEventArtifactUploaders.add(name, uploader);
     return this;
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/TestSummary.java b/src/main/java/com/google/devtools/build/lib/runtime/TestSummary.java
index 97c66cb8e6..4c8d46825f 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/TestSummary.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/TestSummary.java
@@ -18,6 +18,7 @@ import com.google.common.base.Preconditions;
 import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.ComparisonChain;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.devtools.build.lib.analysis.AliasProvider;
@@ -490,6 +491,14 @@ public class TestSummary implements Comparable<TestSummary>, BuildEventWithOrder
   }
 
   @Override
+  public ImmutableSet<Path> referencedLocalFiles() {
+    ImmutableSet.Builder<Path> artifacts = ImmutableSet.builder();
+    artifacts.addAll(getFailedLogs());
+    artifacts.addAll(getPassedLogs());
+    return artifacts.build();
+  }
+
+  @Override
   public BuildEventStreamProtos.BuildEvent asStreamProto(BuildEventContext converters) {
     PathConverter pathConverter = converters.pathConverter();
     BuildEventStreamProtos.TestSummary.Builder summaryBuilder =
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/actiongraph/KnownConfigurations.java b/src/main/java/com/google/devtools/build/lib/skyframe/actiongraph/KnownConfigurations.java
index 59626a73a6..32da894774 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/actiongraph/KnownConfigurations.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/actiongraph/KnownConfigurations.java
@@ -28,7 +28,7 @@ public class KnownConfigurations extends BaseCache<BuildEvent, AnalysisProtos.Co
   @Override
   AnalysisProtos.Configuration createProto(BuildEvent config, String id) {
     BuildEventStreamProtos.Configuration configProto =
-        config.asStreamProto(/*converters=*/ null).getConfiguration();
+        config.asStreamProto(/*context=*/ null).getConfiguration();
     return AnalysisProtos.Configuration.newBuilder()
         .setMnemonic(configProto.getMnemonic())
         .setPlatformName(configProto.getPlatformName())