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

13 files changed, 382 insertions, 165 deletions

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");
   }
 }