First cl for verbose workspaces (ability to log certain potentially non-hermetic events that happen as part of repository rules).

In the interest of smaller cls, adding plumbing first with the rest to follow.

Creates and posts a new EventBus message for workspace rule events (only execution for now); conditional on a flag, registers a listener to output those events.

In the future:
- Better structure for the events: will create a proto with appropriate messages and more information per event
- Add more events
- Allowing to specify log file rather than dumping to INFO
- Log levels, full or alerts only

RELNOTES: None
PiperOrigin-RevId: 203132761

6 files changed, 179 insertions, 2 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/bazel/Bazel.java b/src/main/java/com/google/devtools/build/lib/bazel/Bazel.java
index e96c815036..38a8ae77e1 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/Bazel.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/Bazel.java
@@ -43,6 +43,7 @@ public final class Bazel {
           com.google.devtools.build.lib.bazel.BazelWorkspaceStatusModule.class,
           com.google.devtools.build.lib.bazel.BazelDiffAwarenessModule.class,
           com.google.devtools.build.lib.bazel.BazelRepositoryModule.class,
+          com.google.devtools.build.lib.bazel.debug.WorkspaceRuleModule.class,
           com.google.devtools.build.lib.skylarkdebug.module.SkylarkDebuggerModule.class,
           com.google.devtools.build.lib.bazel.repository.RepositoryResolvedModule.class,
           com.google.devtools.build.lib.bazel.SpawnLogModule.class,
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/debug/BUILD b/src/main/java/com/google/devtools/build/lib/bazel/debug/BUILD
new file mode 100644
index 0000000000..208d4e1254
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/bazel/debug/BUILD
@@ -0,0 +1,44 @@
+# Description:
+#   Debugging helpers and modules
+package(
+    default_visibility = ["//src:__subpackages__"],
+)
+
+filegroup(
+    name = "srcs",
+    srcs = glob(["**"]),
+    visibility = [
+        "//src:__pkg__",
+        "//src/main/java/com/google/devtools/build/lib:__pkg__",
+        "//src/test/shell/bazel:__pkg__",
+    ],
+)
+
+java_library(
+    name = "workspace-rule-event",
+    srcs = ["WorkspaceRuleEvent.java"],
+    deps = [
+        "//src/main/java/com/google/devtools/build/lib:events",
+    ],
+)
+
+java_library(
+    name = "workspace-rule-module",
+    srcs = ["WorkspaceRuleModule.java"],
+    deps = [
+        ":debugging-options",
+        ":workspace-rule-event",
+        "//src/main/java/com/google/devtools/build/lib:events",
+        "//src/main/java/com/google/devtools/build/lib:runtime",
+        "//src/main/java/com/google/devtools/common/options",
+        "//third_party:guava",
+    ],
+)
+
+java_library(
+    name = "debugging-options",
+    srcs = ["DebuggingOptions.java"],
+    deps = [
+        "//src/main/java/com/google/devtools/common/options",
+    ],
+)
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/debug/DebuggingOptions.java b/src/main/java/com/google/devtools/build/lib/bazel/debug/DebuggingOptions.java
new file mode 100644
index 0000000000..2761b61d6f
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/bazel/debug/DebuggingOptions.java
@@ -0,0 +1,31 @@
+// 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.bazel.debug;
+
+import com.google.devtools.common.options.Option;
+import com.google.devtools.common.options.OptionDocumentationCategory;
+import com.google.devtools.common.options.OptionEffectTag;
+import com.google.devtools.common.options.OptionsBase;
+
+/** Options for debugging and verbosity tools. */
+public final class DebuggingOptions extends OptionsBase {
+  @Option(
+      name = "experimental_workspace_rules_logging",
+      defaultValue = "null",
+      documentationCategory = OptionDocumentationCategory.LOGGING,
+      effectTags = {OptionEffectTag.UNKNOWN},
+      help = "Log certain Workspace Rules events")
+  public String workspaceRulesLogging;
+}
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/debug/WorkspaceRuleEvent.java b/src/main/java/com/google/devtools/build/lib/bazel/debug/WorkspaceRuleEvent.java
new file mode 100644
index 0000000000..059b08adae
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/bazel/debug/WorkspaceRuleEvent.java
@@ -0,0 +1,40 @@
+// 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.bazel.debug;
+
+import com.google.devtools.build.lib.events.ExtendedEventHandler.ProgressLike;
+import com.google.devtools.build.lib.events.Location;
+
+/** An event to record events happening during workspace rule resolution */
+public final class WorkspaceRuleEvent implements ProgressLike {
+  String location;
+  String description;
+
+  /**
+   * Creates a new WorkspaceRuleEvent with the given description.
+   *
+   * <p>Note: we will add more granular information as needed.
+   */
+  public WorkspaceRuleEvent(Location location, String description) {
+    this.location = location.print();
+    this.description = description;
+  }
+
+  /*
+   * @return a message to log for this event
+   */
+  public String logMessage() {
+    return location + ": " + description;
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/debug/WorkspaceRuleModule.java b/src/main/java/com/google/devtools/build/lib/bazel/debug/WorkspaceRuleModule.java
new file mode 100644
index 0000000000..bd5406d478
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/bazel/debug/WorkspaceRuleModule.java
@@ -0,0 +1,55 @@
+// 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.bazel.debug;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.eventbus.EventBus;
+import com.google.common.eventbus.Subscribe;
+import com.google.devtools.build.lib.events.Event;
+import com.google.devtools.build.lib.events.Reporter;
+import com.google.devtools.build.lib.runtime.BlazeModule;
+import com.google.devtools.build.lib.runtime.CommandEnvironment;
+import com.google.devtools.common.options.OptionsBase;
+
+/** A module for logging workspace rule events */
+public final class WorkspaceRuleModule extends BlazeModule {
+  private Reporter reporter;
+  private EventBus eventBus;
+
+  @Override
+  public void beforeCommand(CommandEnvironment env) {
+
+    reporter = env.getReporter();
+    eventBus = env.getEventBus();
+
+    if (env.getOptions() == null || env.getOptions().getOptions(DebuggingOptions.class) == null) {
+      reporter.handle(Event.error("Installation is corrupt: could not retrieve debugging options"));
+      return;
+    }
+
+    if (env.getOptions().getOptions(DebuggingOptions.class).workspaceRulesLogging != null) {
+      eventBus.register(this);
+    }
+  }
+
+  @Override
+  public Iterable<Class<? extends OptionsBase>> getCommonCommandOptions() {
+    return ImmutableList.<Class<? extends OptionsBase>>of(DebuggingOptions.class);
+  }
+
+  @Subscribe
+  public void workspaceRuleEventReceived(WorkspaceRuleEvent event) {
+    reporter.handle(Event.info(event.logMessage()));
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContext.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContext.java
index f245e1dc73..476c47c3dd 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContext.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContext.java
@@ -19,6 +19,7 @@ import com.google.common.base.Optional;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.actions.FileValue;
+import com.google.devtools.build.lib.bazel.debug.WorkspaceRuleEvent;
 import com.google.devtools.build.lib.bazel.repository.DecompressorDescriptor;
 import com.google.devtools.build.lib.bazel.repository.DecompressorValue;
 import com.google.devtools.build.lib.bazel.repository.cache.RepositoryCache.KeyType;
@@ -230,9 +231,14 @@ public class SkylarkRepositoryContext
 
   @Override
   public SkylarkExecutionResult execute(
-      SkylarkList<Object> arguments, Integer timeout, SkylarkDict<String, String> environment,
-      boolean quiet)
+      SkylarkList<Object> arguments,
+      Integer timeout,
+      SkylarkDict<String, String> environment,
+      boolean quiet,
+      Location location)
       throws EvalException, RepositoryFunctionException {
+    WorkspaceRuleEvent w = new WorkspaceRuleEvent(location, "Executing a command.");
+    env.getListener().post(w);
     createDirectory(outputDirectory);
     return SkylarkExecutionResult.builder(osObject.getEnvironmentVariables())
         .addArguments(arguments)