java_sdk_library does the apicheck by default

droiddoc now supports apicheck. java_sdk_library uses it to
automatically perform apichecks against the not-yet-release API and
the latest-released API.

A module type prebuilt_apis is added. It finds api txt files and creates
filegroup modules so that it can be referenced from java_sdk_library
across the module boundary.

Bug: 77575606
Test: m -j
Test: m -j checkapi
Test: m -j update-api
Change-Id: I0ba859972eac060296e1df2e71c4e047392d4877

1 files changed, 140 insertions, 0 deletions

diff --git a/java/prebuilt_apis.go b/java/prebuilt_apis.go
new file mode 100644
index 00000000..50318bb2
--- /dev/null
+++ b/java/prebuilt_apis.go
@@ -0,0 +1,140 @@
+// Copyright 2018 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 java
+
+import (
+	"android/soong/android"
+	"sort"
+	"strconv"
+	"strings"
+
+	"github.com/google/blueprint/proptools"
+)
+
+// prebuilt_apis is a meta-module that generates filegroup modules for all
+// API txt files found under the directory where the Android.bp is located.
+// Specificaly, an API file located at ./<ver>/<scope>/api/<module>.txt
+// generates a filegroup module named <module>-api.<scope>.<ver>.
+//
+// It also creates <module>-api.<scope>.latest for the lastest <ver>.
+//
+func init() {
+	android.RegisterModuleType("prebuilt_apis", prebuiltApisFactory)
+
+	android.PreArchMutators(func(ctx android.RegisterMutatorsContext) {
+		ctx.TopDown("prebuilt_apis", prebuiltApisMutator).Parallel()
+	})
+}
+
+type prebuiltApis struct {
+	android.ModuleBase
+}
+
+func (module *prebuiltApis) DepsMutator(ctx android.BottomUpMutatorContext) {
+	// no need to implement
+}
+
+func (module *prebuiltApis) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	// no need to implement
+}
+
+func parseApiFilePath(ctx android.BaseModuleContext, path string) (module string, apiver int, scope string) {
+	elements := strings.Split(path, "/")
+	ver, err := strconv.Atoi(elements[0])
+	if err != nil {
+		ctx.ModuleErrorf("invalid version %q found in path: %q", elements[0], path)
+		return
+	}
+	apiver = ver
+
+	scope = elements[1]
+	if scope != "public" && scope != "system" && scope != "test" {
+		ctx.ModuleErrorf("invalid scope %q found in path: %q", scope, path)
+		return
+	}
+
+	// elements[2] is string literal "api". skipping.
+	module = strings.TrimSuffix(elements[3], ".txt")
+	return
+}
+
+func createFilegroup(mctx android.TopDownMutatorContext, module string, scope string, apiver string, path string) {
+	fgName := module + ".api." + scope + "." + apiver
+	filegroupProps := struct {
+		Name *string
+		Srcs []string
+	}{}
+	filegroupProps.Name = proptools.StringPtr(fgName)
+	filegroupProps.Srcs = []string{path}
+	mctx.CreateModule(android.ModuleFactoryAdaptor(android.FileGroupFactory), &filegroupProps)
+}
+
+func prebuiltApisMutator(mctx android.TopDownMutatorContext) {
+	if _, ok := mctx.Module().(*prebuiltApis); ok {
+		mydir := mctx.ModuleDir() + "/"
+		// <apiver>/<scope>/api/<module>.txt
+		files, err := mctx.GlobWithDeps(mydir+"*/*/api/*.txt", nil)
+		if err != nil {
+			mctx.ModuleErrorf("failed to glob api txt files under %q: %s", mydir, err)
+		}
+		if len(files) == 0 {
+			mctx.ModuleErrorf("no api file found under %q", mydir)
+		}
+
+		// construct a map to find out the latest api file path
+		// for each (<module>, <scope>) pair.
+		type latestApiInfo struct {
+			module string
+			scope  string
+			apiver int
+			path   string
+		}
+		m := make(map[string]latestApiInfo)
+
+		for _, f := range files {
+			// create a filegroup for each api txt file
+			localPath := strings.TrimPrefix(f, mydir)
+			module, apiver, scope := parseApiFilePath(mctx, localPath)
+			createFilegroup(mctx, module, scope, strconv.Itoa(apiver), localPath)
+
+			// find the latest apiver
+			key := module + "." + scope
+			info, ok := m[key]
+			if !ok {
+				m[key] = latestApiInfo{module, scope, apiver, localPath}
+			} else if apiver > info.apiver {
+				info.apiver = apiver
+				info.path = localPath
+			}
+		}
+		// create filegroups for the latest version of (<module>, <scope>) pairs
+		// sort the keys in order to make build.ninja stable
+		keys := make([]string, 0, len(m))
+		for k := range m {
+			keys = append(keys, k)
+		}
+		sort.Strings(keys)
+		for _, k := range keys {
+			info := m[k]
+			createFilegroup(mctx, info.module, info.scope, "latest", info.path)
+		}
+	}
+}
+
+func prebuiltApisFactory() android.Module {
+	module := &prebuiltApis{}
+	android.InitAndroidModule(module)
+	return module
+}