Use aquery to declare bazel actions in the ninja file.

This effectively moves execution of Bazel actions outside of soong_build
and alongside ninja execution of the actual ninja files, whether that be
by ninja or by Bazel itself.

This almost allows for mixed builds and Bazel-as-Ninja-executor to
coexist, but requires hacks explained in b/175307058.

Test: Treehugger
Test: lunch aosp_flame && USE_BAZEL_ANALYSIS=1 m libc
Test: lunch aosp_flame && USE_BAZEL=1 USE_BAZEL_ANALYSIS=1 m libc,
though this requires a hack of the main BUILD file. See b/175307058

Change-Id: Ia2f6b0f1057e8cea3809de66d8287f13d84b510c

bazel/aquery.go

@@ -0,0 +1,116 @@
+// Copyright 2020 Google Inc. 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 bazel
+
+import (
+	"encoding/json"
+	"strings"
+
+	"github.com/google/blueprint/proptools"
+)
+
+// artifact contains relevant portions of Bazel's aquery proto, Artifact.
+// Represents a single artifact, whether it's a source file or a derived output file.
+type artifact struct {
+	Id       string
+	ExecPath string
+}
+
+// KeyValuePair represents Bazel's aquery proto, KeyValuePair.
+type KeyValuePair struct {
+	Key   string
+	Value string
+}
+
+// depSetOfFiles contains relevant portions of Bazel's aquery proto, DepSetOfFiles.
+// Represents a data structure containing one or more files. Depsets in Bazel are an efficient
+// data structure for storing large numbers of file paths.
+type depSetOfFiles struct {
+	Id string
+	// TODO(cparsons): Handle non-flat depsets.
+	DirectArtifactIds []string
+}
+
+// action contains relevant portions of Bazel's aquery proto, Action.
+// Represents a single command line invocation in the Bazel build graph.
+type action struct {
+	Arguments            []string
+	EnvironmentVariables []KeyValuePair
+	InputDepSetIds       []string
+	Mnemonic             string
+	OutputIds            []string
+}
+
+// actionGraphContainer contains relevant portions of Bazel's aquery proto, ActionGraphContainer.
+// An aquery response from Bazel contains a single ActionGraphContainer proto.
+type actionGraphContainer struct {
+	Artifacts     []artifact
+	Actions       []action
+	DepSetOfFiles []depSetOfFiles
+}
+
+// BuildStatement contains information to register a build statement corresponding (one to one)
+// with a Bazel action from Bazel's action graph.
+type BuildStatement struct {
+	Command     string
+	OutputPaths []string
+	InputPaths  []string
+	Env         []KeyValuePair
+	Mnemonic    string
+}
+
+// AqueryBuildStatements returns an array of BuildStatements which should be registered (and output
+// to a ninja file) to correspond one-to-one with the given action graph json proto (from a bazel
+// aquery invocation).
+func AqueryBuildStatements(aqueryJsonProto []byte) []BuildStatement {
+	buildStatements := []BuildStatement{}
+
+	var aqueryResult actionGraphContainer
+	json.Unmarshal(aqueryJsonProto, &aqueryResult)
+
+	artifactIdToPath := map[string]string{}
+	for _, artifact := range aqueryResult.Artifacts {
+		artifactIdToPath[artifact.Id] = artifact.ExecPath
+	}
+	depsetIdToArtifactIds := map[string][]string{}
+	for _, depset := range aqueryResult.DepSetOfFiles {
+		depsetIdToArtifactIds[depset.Id] = depset.DirectArtifactIds
+	}
+
+	for _, actionEntry := range aqueryResult.Actions {
+		outputPaths := []string{}
+		for _, outputId := range actionEntry.OutputIds {
+			// TODO(cparsons): Validate the id is present.
+			outputPaths = append(outputPaths, artifactIdToPath[outputId])
+		}
+		inputPaths := []string{}
+		for _, inputDepSetId := range actionEntry.InputDepSetIds {
+			// TODO(cparsons): Validate the id is present.
+			for _, inputId := range depsetIdToArtifactIds[inputDepSetId] {
+				// TODO(cparsons): Validate the id is present.
+				inputPaths = append(inputPaths, artifactIdToPath[inputId])
+			}
+		}
+		buildStatement := BuildStatement{
+			Command:     strings.Join(proptools.ShellEscapeList(actionEntry.Arguments), " "),
+			OutputPaths: outputPaths,
+			InputPaths:  inputPaths,
+			Env:         actionEntry.EnvironmentVariables,
+			Mnemonic:    actionEntry.Mnemonic}
+		buildStatements = append(buildStatements, buildStatement)
+	}
+
+	return buildStatements
+}