Prototype for remote execution using gRPC and Netty transport

This change implements a remote worker that executes work (build or test).
Bazel will be a client of the remote worker. The communication uses gRPC
and Netty as transport.

A single remote worker has little advantage over running locally. Additional
infrastructure is needed to run workers on multiple machines and distributing
the work among them.

This change provides the basic building blocks for a distributed build farm.

(Mainly reformatting changes compared to https://bazel-review.googlesource.com/3110, some BUILD file changes.)

--
Change-Id: If7d285444ef42a6823b59443af17b61b04b9ce6a
Reviewed-on: https://bazel-review.googlesource.com/#/c/3110/
MOS_MIGRATED_REVID=122376861

1 files changed, 208 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/remote/MemcacheWorkExecutor.java b/src/main/java/com/google/devtools/build/lib/remote/MemcacheWorkExecutor.java
new file mode 100644
index 0000000000..04c3c3f1d2
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/remote/MemcacheWorkExecutor.java
@@ -0,0 +1,208 @@
+// Copyright 2016 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.remote;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.common.util.concurrent.ListenableFuture;
+import com.google.devtools.build.lib.actions.ActionInput;
+import com.google.devtools.build.lib.actions.ActionInputFileCache;
+import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
+import com.google.devtools.build.lib.remote.RemoteProtocol.FileEntry;
+import com.google.devtools.build.lib.remote.RemoteProtocol.RemoteWorkRequest;
+import com.google.devtools.build.lib.remote.RemoteProtocol.RemoteWorkResponse;
+import com.google.devtools.build.lib.remote.RemoteWorkGrpc.RemoteWorkFutureStub;
+import com.google.devtools.build.lib.shell.Command;
+import com.google.devtools.build.lib.shell.CommandException;
+import com.google.devtools.build.lib.shell.CommandResult;
+import com.google.devtools.build.lib.vfs.FileSystemUtils;
+import com.google.devtools.build.lib.vfs.Path;
+
+import io.grpc.ManagedChannel;
+import io.grpc.netty.NettyChannelBuilder;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.FileAlreadyExistsException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+/**
+ * Implementation of {@link RemoteWorkExecutor} that uses MemcacheActionCache and gRPC for
+ * communicating the work, inputs and outputs.
+ */
+@ThreadSafe
+public class MemcacheWorkExecutor implements RemoteWorkExecutor {
+  /**
+   * A cache used to store the input and output files as well as the build status
+   * of the remote work.
+   */
+  protected final MemcacheActionCache cache;
+
+  /** Execution root for running this work locally. */
+  private final Path execRoot;
+
+  /** Channel over which to send work to run remotely. */
+  private final ManagedChannel channel;
+
+  private static final int MAX_WORK_SIZE_BYTES = 1024 * 1024 * 512;
+
+  /**
+   * This constructor is used when this class is used in a client.
+   * It requires a host address and port to connect to a remote service.
+   */
+  private MemcacheWorkExecutor(MemcacheActionCache cache, String host, int port) {
+    this.cache = cache;
+    this.execRoot = null;
+    this.channel = NettyChannelBuilder.forAddress(host, port).usePlaintext(true).build();
+  }
+
+  /**
+   * This constructor is used when this class is used in the remote worker.
+   * A path to the execution root is needed for executing work locally.
+   */
+  private MemcacheWorkExecutor(MemcacheActionCache cache, Path execRoot) {
+    this.cache = cache;
+    this.execRoot = execRoot;
+    this.channel = null;
+  }
+
+  /**
+   * Create an instance of MemcacheWorkExecutor that talks to a remote server.
+   * @param cache An instance of MemcacheActionCache.
+   * @param host Hostname of the server to connect to.
+   * @param port Port of the server to connect to.
+   * @return An instance of MemcacheWorkExecutor that talks to a remote server.
+   */
+  public static MemcacheWorkExecutor createRemoteWorkExecutor(
+      MemcacheActionCache cache, String host, int port) {
+    return new MemcacheWorkExecutor(cache, host, port);
+  }
+
+  /**
+   * Create an instance of MemcacheWorkExecutor that runs locally.
+   * @param cache An instance of MemcacheActionCache.
+   * @param execRoot Path of the execution root where work is executed.
+   * @return An instance of MemcacheWorkExecutor tthat runs locally in the execution root.
+   */
+  public static MemcacheWorkExecutor createLocalWorkExecutor(
+      MemcacheActionCache cache, Path execRoot) {
+    return new MemcacheWorkExecutor(cache, execRoot);
+  }
+
+  @Override
+  public ListenableFuture<RemoteWorkResponse> executeRemotely(
+      Path execRoot,
+      ActionInputFileCache actionCache,
+      String actionOutputKey,
+      Collection<String> arguments,
+      Collection<ActionInput> inputs,
+      ImmutableMap<String, String> environment,
+      Collection<? extends ActionInput> outputs,
+      int timeout)
+      throws IOException, WorkTooLargeException {
+    RemoteWorkRequest.Builder work = RemoteWorkRequest.newBuilder();
+    work.setOutputKey(actionOutputKey);
+
+    long workSize = 0;
+    for (ActionInput input : inputs) {
+      if (!(input instanceof Artifact)) {
+        continue;
+      }
+      if (!actionCache.isFile((Artifact) input)) {
+        continue;
+      }
+      workSize += actionCache.getSizeInBytes(input);
+    }
+
+    if (workSize > MAX_WORK_SIZE_BYTES) {
+      throw new WorkTooLargeException("Work is too large: " + workSize + " bytes.");
+    }
+
+    // Save all input files to cache.
+    for (ActionInput input : inputs) {
+      Path file = execRoot.getRelative(input.getExecPathString());
+
+      if (file.isDirectory()) {
+        // TODO(alpha): Handle this case better.
+        throw new UnsupportedOperationException(
+            "Does not support directory artifacts: " + file + ".");
+      }
+
+      String contentKey = cache.putFileIfNotExist(actionCache, input);
+      work.addInputFilesBuilder()
+          .setPath(input.getExecPathString())
+          .setContentKey(contentKey)
+          .setExecutable(file.isExecutable());
+    }
+
+    work.addAllArguments(arguments);
+    work.getMutableEnvironment().putAll(environment);
+    for (ActionInput output : outputs) {
+      work.addOutputFilesBuilder().setPath(output.getExecPathString());
+    }
+
+    RemoteWorkFutureStub stub = RemoteWorkGrpc.newFutureStub(channel);
+    work.setTimeout(timeout);
+    return stub.executeSynchronously(work.build());
+  }
+
+  /** Execute a work item locally. */
+  public RemoteWorkResponse executeLocally(RemoteWorkRequest work) throws IOException {
+    ByteArrayOutputStream stdout = new ByteArrayOutputStream();
+    ByteArrayOutputStream stderr = new ByteArrayOutputStream();
+    try {
+      // Prepare directories and input files.
+      for (FileEntry input : work.getInputFilesList()) {
+        Path file = execRoot.getRelative(input.getPath());
+        FileSystemUtils.createDirectoryAndParents(file.getParentDirectory());
+        cache.writeFile(input.getContentKey(), file, input.getExecutable());
+      }
+
+      List<Path> outputs = new ArrayList<>(work.getOutputFilesList().size());
+      for (FileEntry output : work.getOutputFilesList()) {
+        Path file = execRoot.getRelative(output.getPath());
+        if (file.exists()) {
+          throw new FileAlreadyExistsException("Output file already exists: " + file);
+        }
+        FileSystemUtils.createDirectoryAndParents(file.getParentDirectory());
+        outputs.add(file);
+      }
+
+      Command cmd =
+          new Command(
+              work.getArgumentsList().toArray(new String[] {}),
+              work.getEnvironment(),
+              new File(execRoot.getPathString()));
+      CommandResult result =
+          cmd.execute(Command.NO_INPUT, Command.NO_OBSERVER, stdout, stderr, true);
+      cache.putActionOutput(work.getOutputKey(), execRoot, outputs);
+      return RemoteWorkResponse.newBuilder()
+          .setSuccess(result.getTerminationStatus().success())
+          .setOut(stdout.toString())
+          .setErr(stderr.toString())
+          .build();
+    } catch (CommandException e) {
+      return RemoteWorkResponse.newBuilder()
+          .setSuccess(false)
+          .setOut(stdout.toString())
+          .setErr(stderr.toString())
+          .setException(e.toString())
+          .build();
+    }
+  }
+}