Skylark debug server: add serialization code

Small self-contained part of the debug server (see unknown commit for the
larger picture).

PiperOrigin-RevId: 197140094

7 files changed, 394 insertions, 0 deletions

diff --git a/src/BUILD b/src/BUILD
index 6525feb2c6..d1ef9366fd 100644
--- a/src/BUILD
+++ b/src/BUILD
@@ -351,6 +351,7 @@ genrule(
     srcs = [
         "//src/main/protobuf:dist_jars",
         "//src/main/java/com/google/devtools/build/lib/buildeventstream/proto:dist_jars",
+        "//src/main/java/com/google/devtools/build/lib/skylarkdebug/proto:dist_jars",
         "@googleapis//:dist_jars",
     ],
     outs = ["derived_java_srcs.zip"],
diff --git a/src/main/java/com/google/devtools/build/lib/BUILD b/src/main/java/com/google/devtools/build/lib/BUILD
index 432a4d2ac4..b7d86d6f6d 100644
--- a/src/main/java/com/google/devtools/build/lib/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/BUILD
@@ -60,6 +60,7 @@ filegroup(
         "//src/main/java/com/google/devtools/build/lib/skylarkbuildapi/cpp:srcs",
         "//src/main/java/com/google/devtools/build/lib/skylarkbuildapi/java:srcs",
         "//src/main/java/com/google/devtools/build/lib/skylarkdebug/proto:srcs",
+        "//src/main/java/com/google/devtools/build/lib/skylarkdebug/server:srcs",
         "//src/main/java/com/google/devtools/build/lib/skylarkinterface/processor:srcs",
         "//src/main/java/com/google/devtools/build/lib/ssd:srcs",
         "//src/main/java/com/google/devtools/build/lib/standalone:srcs",
diff --git a/src/main/java/com/google/devtools/build/lib/skylarkdebug/server/BUILD b/src/main/java/com/google/devtools/build/lib/skylarkdebug/server/BUILD
new file mode 100644
index 0000000000..42768bb69d
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skylarkdebug/server/BUILD
@@ -0,0 +1,20 @@
+package(default_visibility = ["//src:__subpackages__"])
+
+filegroup(
+    name = "srcs",
+    srcs = glob(["**"]),
+    visibility = ["//src/main/java/com/google/devtools/build/lib:__pkg__"],
+)
+
+java_library(
+    name = "server",
+    srcs = glob(["*.java"]),
+    deps = [
+        "//src/main/java/com/google/devtools/build/lib:skylarkinterface",
+        "//src/main/java/com/google/devtools/build/lib:syntax",
+        "//src/main/java/com/google/devtools/build/lib/collect/nestedset",
+        "//src/main/java/com/google/devtools/build/lib/skylarkdebug/proto:skylark_debugging_java_proto",
+        "//third_party:guava",
+        "//third_party:jsr305",
+    ],
+)
diff --git a/src/main/java/com/google/devtools/build/lib/skylarkdebug/server/DebuggerSerialization.java b/src/main/java/com/google/devtools/build/lib/skylarkdebug/server/DebuggerSerialization.java
new file mode 100644
index 0000000000..70d716332a
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skylarkdebug/server/DebuggerSerialization.java
@@ -0,0 +1,140 @@
+// 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.skylarkdebug.server;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Ordering;
+import com.google.devtools.build.lib.collect.nestedset.NestedSetView;
+import com.google.devtools.build.lib.skylarkdebugging.SkylarkDebuggingProtos;
+import com.google.devtools.build.lib.skylarkdebugging.SkylarkDebuggingProtos.Value;
+import com.google.devtools.build.lib.syntax.ClassObject;
+import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.lib.syntax.EvalUtils;
+import com.google.devtools.build.lib.syntax.Printer;
+import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
+import java.lang.reflect.Array;
+import java.util.Map;
+
+/** Helper class for creating {@link SkylarkDebuggingProtos.Value} from skylark objects. */
+final class DebuggerSerialization {
+
+  static Value getValueProto(String label, Object value) {
+    // TODO(bazel-team): prune cycles, and provide a way to limit breadth/depth of children reported
+    return Value.newBuilder()
+        .setLabel(label)
+        // TODO(bazel-team): omit type details for non-Skylark values
+        .setType(EvalUtils.getDataTypeName(value))
+        .setDescription(Printer.repr(value))
+        .addAllChild(getChildren(value))
+        .build();
+  }
+
+  private static Value errorValue(String errorMessage) {
+    return Value.newBuilder().setLabel("Error").setDescription(errorMessage).build();
+  }
+
+  private static ImmutableList<Value> getChildren(Object value) {
+    // TODO(bazel-team): move child-listing logic to SkylarkValue where practical
+    if (value instanceof ClassObject) {
+      return getChildren((ClassObject) value);
+    }
+    if (value instanceof SkylarkNestedSet) {
+      return getChildren((SkylarkNestedSet) value);
+    }
+    if (value instanceof NestedSetView) {
+      return getChildren((NestedSetView) value);
+    }
+    if (value instanceof Map) {
+      return getChildren(((Map) value).entrySet());
+    }
+    if (value instanceof Map.Entry) {
+      return getChildren((Map.Entry) value);
+    }
+    if (value instanceof Iterable) {
+      return getChildren((Iterable) value);
+    }
+    if (value.getClass().isArray()) {
+      return getArrayChildren(value);
+    }
+    // fallback to assuming there are no children
+    return ImmutableList.of();
+  }
+
+  private static ImmutableList<Value> getChildren(ClassObject classObject) {
+    ImmutableList.Builder<Value> builder = ImmutableList.builder();
+    ImmutableList<String> keys;
+    try {
+      keys = Ordering.natural().immutableSortedCopy(classObject.getFieldNames());
+    } catch (EvalException e) {
+      return ImmutableList.of(errorValue("Error retrieving field names: " + e.getMessage()));
+    }
+    for (String key : keys) {
+      Object value;
+      try {
+        value = classObject.getValue(key);
+      } catch (EvalException e) {
+        return ImmutableList.of(
+            errorValue(
+                String.format("Error retrieving value for field '%s': %s", key, e.getMessage())));
+      }
+      if (value != null) {
+        builder.add(getValueProto(key, value));
+      }
+    }
+    return builder.build();
+  }
+
+  private static ImmutableList<Value> getChildren(SkylarkNestedSet nestedSet) {
+    Class<?> type = nestedSet.getContentType().getType();
+    return ImmutableList.<Value>builder()
+        .add(
+            Value.newBuilder()
+                .setLabel("order")
+                .setType("Traversal order")
+                .setDescription(nestedSet.getOrder().getSkylarkName())
+                .build())
+        .addAll(getChildren(new NestedSetView<>(nestedSet.getSet(type))))
+        .build();
+  }
+
+  private static ImmutableList<Value> getChildren(NestedSetView<?> nestedSet) {
+    return ImmutableList.of(
+        getValueProto("directs", nestedSet.directs()),
+        getValueProto("transitives", nestedSet.transitives()));
+  }
+
+  private static ImmutableList<Value> getChildren(Map.Entry<?, ?> entry) {
+    return ImmutableList.of(
+        getValueProto("key", entry.getKey()), getValueProto("value", entry.getValue()));
+  }
+
+  private static ImmutableList<Value> getChildren(Iterable<?> iterable) {
+    ImmutableList.Builder<Value> builder = ImmutableList.builder();
+    int index = 0;
+    for (Object value : iterable) {
+      builder.add(getValueProto(String.format("[%d]", index++), value));
+    }
+    return builder.build();
+  }
+
+  private static ImmutableList<Value> getArrayChildren(Object array) {
+    ImmutableList.Builder<Value> builder = ImmutableList.builder();
+    int index = 0;
+    for (int i = 0; i < Array.getLength(array); i++) {
+      builder.add(getValueProto(String.format("[%d]", index++), Array.get(array, i)));
+    }
+    return builder.build();
+  }
+}
diff --git a/src/test/java/com/google/devtools/build/lib/BUILD b/src/test/java/com/google/devtools/build/lib/BUILD
index 52c95b19cc..887620485a 100644
--- a/src/test/java/com/google/devtools/build/lib/BUILD
+++ b/src/test/java/com/google/devtools/build/lib/BUILD
@@ -58,6 +58,7 @@ filegroup(
         "//src/test/java/com/google/devtools/build/lib/skyframe/serialization:srcs",
         "//src/test/java/com/google/devtools/build/lib/skyframe:srcs",
         "//src/test/java/com/google/devtools/build/lib/skylark:srcs",
+        "//src/test/java/com/google/devtools/build/lib/skylarkdebug/server:srcs",
         "//src/test/java/com/google/devtools/build/lib/skylarkinterface/processor:srcs",
     ],
     visibility = ["//src:__pkg__"],
diff --git a/src/test/java/com/google/devtools/build/lib/skylarkdebug/server/BUILD b/src/test/java/com/google/devtools/build/lib/skylarkdebug/server/BUILD
new file mode 100644
index 0000000000..5d9f881575
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/skylarkdebug/server/BUILD
@@ -0,0 +1,26 @@
+package(
+    default_testonly = 1,
+    default_visibility = ["//src:__subpackages__"],
+)
+
+filegroup(
+    name = "srcs",
+    testonly = 0,
+    srcs = glob(["**"]),
+    visibility = ["//src/test/java/com/google/devtools/build/lib:__pkg__"],
+)
+
+java_test(
+    name = "DebuggerSerializationTest",
+    srcs = glob(["DebuggerSerializationTest.java"]),
+    deps = [
+        "//src/main/java/com/google/devtools/build/lib:syntax",
+        "//src/main/java/com/google/devtools/build/lib/collect/nestedset",
+        "//src/main/java/com/google/devtools/build/lib/skylarkdebug/proto:skylark_debugging_java_proto",
+        "//src/main/java/com/google/devtools/build/lib/skylarkdebug/server",
+        "//third_party:guava",
+        "//third_party:jsr305",
+        "//third_party:junit4",
+        "//third_party:truth",
+    ],
+)
diff --git a/src/test/java/com/google/devtools/build/lib/skylarkdebug/server/DebuggerSerializationTest.java b/src/test/java/com/google/devtools/build/lib/skylarkdebug/server/DebuggerSerializationTest.java
new file mode 100644
index 0000000000..525f1ce005
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/skylarkdebug/server/DebuggerSerializationTest.java
@@ -0,0 +1,205 @@
+// 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.skylarkdebug.server;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.collect.nestedset.NestedSet;
+import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
+import com.google.devtools.build.lib.collect.nestedset.NestedSetView;
+import com.google.devtools.build.lib.skylarkdebugging.SkylarkDebuggingProtos.Value;
+import com.google.devtools.build.lib.syntax.EvalUtils;
+import com.google.devtools.build.lib.syntax.Printer;
+import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
+import java.util.Map;
+import java.util.Set;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Unit tests for {@link DebuggerSerialization}. */
+@RunWith(JUnit4.class)
+public final class DebuggerSerializationTest {
+
+  @Test
+  public void testSimpleNestedSet() {
+    Set<String> children = ImmutableSet.of("a", "b");
+    SkylarkNestedSet set =
+        SkylarkNestedSet.of(Object.class, NestedSetBuilder.stableOrder().addAll(children).build());
+
+    Value value = DebuggerSerialization.getValueProto("name", set);
+
+    assertTypeAndDescription(set, value);
+    assertThat(value.getChildList()).hasSize(3);
+    assertThat(value.getChild(0))
+        .isEqualTo(
+            Value.newBuilder()
+                .setLabel("order")
+                .setType("Traversal order")
+                .setDescription("default")
+                .build());
+    assertEqualIgnoringTypeAndDescription(
+        value.getChild(1), DebuggerSerialization.getValueProto("directs", children));
+    assertEqualIgnoringTypeAndDescription(
+        value.getChild(2), DebuggerSerialization.getValueProto("transitives", ImmutableList.of()));
+  }
+
+  @Test
+  public void testNestedSetWithNestedChildren() {
+    NestedSet<String> innerNestedSet =
+        NestedSetBuilder.<String>stableOrder().add("inner1").add("inner2").build();
+    ImmutableSet<String> directChildren = ImmutableSet.of("a", "b");
+    SkylarkNestedSet outerSet =
+        SkylarkNestedSet.of(
+            String.class,
+            NestedSetBuilder.<String>linkOrder()
+                .addAll(directChildren)
+                .addTransitive(innerNestedSet)
+                .build());
+
+    Value value = DebuggerSerialization.getValueProto("name", outerSet);
+
+    assertTypeAndDescription(outerSet, value);
+    assertThat(value.getChildList()).hasSize(3);
+    assertThat(value.getChild(0))
+        .isEqualTo(
+            Value.newBuilder()
+                .setLabel("order")
+                .setType("Traversal order")
+                .setDescription("topological")
+                .build());
+    assertEqualIgnoringTypeAndDescription(
+        value.getChild(1), DebuggerSerialization.getValueProto("directs", directChildren));
+    assertEqualIgnoringTypeAndDescription(
+        value.getChild(2),
+        DebuggerSerialization.getValueProto(
+            "transitives", ImmutableList.of(new NestedSetView<>(innerNestedSet))));
+  }
+
+  @Test
+  public void testSimpleMap() {
+    Map<String, Integer> map = ImmutableMap.of("a", 1, "b", 2);
+
+    Value value = DebuggerSerialization.getValueProto("name", map);
+
+    assertTypeAndDescription(map, value);
+    assertThat(value.getChildList()).hasSize(2);
+    assertThat(value.getChild(0).getLabel()).isEqualTo("[0]");
+    assertThat(value.getChild(0).getChildList())
+        .isEqualTo(
+            ImmutableList.of(
+                DebuggerSerialization.getValueProto("key", "a"),
+                DebuggerSerialization.getValueProto("value", 1)));
+    assertThat(value.getChild(1).getLabel()).isEqualTo("[1]");
+    assertThat(value.getChild(1).getChildList())
+        .isEqualTo(
+            ImmutableList.of(
+                DebuggerSerialization.getValueProto("key", "b"),
+                DebuggerSerialization.getValueProto("value", 2)));
+  }
+
+  @Test
+  public void testNestedMap() {
+    Set<String> set = ImmutableSet.of("a", "b");
+    Map<String, Object> map = ImmutableMap.of("a", set);
+
+    Value value = DebuggerSerialization.getValueProto("name", map);
+
+    assertTypeAndDescription(map, value);
+    assertThat(value.getChildList()).hasSize(1);
+    assertThat(value.getChild(0).getLabel()).isEqualTo("[0]");
+    assertThat(value.getChild(0).getChildList())
+        .isEqualTo(
+            ImmutableList.of(
+                DebuggerSerialization.getValueProto("key", "a"),
+                DebuggerSerialization.getValueProto("value", set)));
+  }
+
+  @Test
+  public void testSimpleIterable() {
+    Iterable<Integer> iter = ImmutableList.of(1, 2);
+
+    Value value = DebuggerSerialization.getValueProto("name", iter);
+
+    assertTypeAndDescription(iter, value);
+    assertThat(value.getChildList()).hasSize(2);
+    assertThat(value.getChild(0)).isEqualTo(DebuggerSerialization.getValueProto("[0]", 1));
+    assertThat(value.getChild(1)).isEqualTo(DebuggerSerialization.getValueProto("[1]", 2));
+  }
+
+  @Test
+  public void testNestedIterable() {
+    Iterable<Object> iter = ImmutableList.of(ImmutableList.of(1, 2));
+
+    Value value = DebuggerSerialization.getValueProto("name", iter);
+
+    assertTypeAndDescription(iter, value);
+    assertThat(value.getChildList()).hasSize(1);
+    assertThat(value.getChild(0))
+        .isEqualTo(DebuggerSerialization.getValueProto("[0]", ImmutableList.of(1, 2)));
+  }
+
+  @Test
+  public void testSimpleArray() {
+    int[] array = new int[] {1, 2};
+
+    Value value = DebuggerSerialization.getValueProto("name", array);
+
+    assertTypeAndDescription(array, value);
+    assertThat(value.getChildList()).hasSize(2);
+    assertThat(value.getChild(0)).isEqualTo(DebuggerSerialization.getValueProto("[0]", 1));
+    assertThat(value.getChild(1)).isEqualTo(DebuggerSerialization.getValueProto("[1]", 2));
+  }
+
+  @Test
+  public void testNestedArray() {
+    Object[] array = new Object[] {1, ImmutableList.of(2, 3)};
+
+    Value value = DebuggerSerialization.getValueProto("name", array);
+
+    assertTypeAndDescription(array, value);
+    assertThat(value.getChildList()).hasSize(2);
+    assertThat(value.getChild(0)).isEqualTo(DebuggerSerialization.getValueProto("[0]", 1));
+    assertThat(value.getChild(1))
+        .isEqualTo(DebuggerSerialization.getValueProto("[1]", ImmutableList.of(2, 3)));
+  }
+
+  @Test
+  public void testUnrecognizedObjectOrSkylarkPrimitiveHasNoChildren() {
+    assertThat(DebuggerSerialization.getValueProto("name", 1).getChildList()).isEmpty();
+    assertThat(DebuggerSerialization.getValueProto("name", "string").getChildList()).isEmpty();
+    assertThat(DebuggerSerialization.getValueProto("name", new Object()).getChildList()).isEmpty();
+  }
+
+  private static void assertTypeAndDescription(Object object, Value value) {
+    assertThat(value.getType()).isEqualTo(EvalUtils.getDataTypeName(object));
+    assertThat(value.getDescription()).isEqualTo(Printer.repr(object));
+  }
+
+  /**
+   * Type and description are implementation dependent (e.g. NestedSetView#directs returns a list
+   * instead of a set if there are no duplicates, which changes both 'type' and 'description').
+   */
+  private static void assertEqualIgnoringTypeAndDescription(Value value1, Value value2) {
+    assertThat(value1.getLabel()).isEqualTo(value2.getLabel());
+    assertThat(value1.getChildCount()).isEqualTo(value2.getChildCount());
+    for (int i = 0; i < value1.getChildCount(); i++) {
+      assertEqualIgnoringTypeAndDescription(value1.getChild(i), value2.getChild(i));
+    }
+  }
+}