find_input_delta: Add jar inspection, metrics generation

This change implements:
- zipfile inspection (for some file extensions)
- changed files metrics generation

Bug: b/376287012
Test: Manual, TH
Change-Id: I18a688c8c6f462cdd7526287c61d38635a9f7709
diff --git a/cmd/find_input_delta/find_input_delta/main.go b/cmd/find_input_delta/find_input_delta/main.go
index 6b657ea..a864584 100644
--- a/cmd/find_input_delta/find_input_delta/main.go
+++ b/cmd/find_input_delta/find_input_delta/main.go
@@ -85,4 +85,11 @@
 	if err = file_list.Format(os.Stdout, template); err != nil {
 		panic(err)
 	}
+
+	metrics_file := os.Getenv("SOONG_METRICS_AGGREGATION_FILE")
+	if metrics_file != "" {
+		if err = file_list.SendMetrics(metrics_file); err != nil {
+			panic(err)
+		}
+	}
 }
diff --git a/cmd/find_input_delta/find_input_delta_lib/Android.bp b/cmd/find_input_delta/find_input_delta_lib/Android.bp
index 95bdba8..ef9c65b 100644
--- a/cmd/find_input_delta/find_input_delta_lib/Android.bp
+++ b/cmd/find_input_delta/find_input_delta_lib/Android.bp
@@ -25,6 +25,7 @@
         "golang-protobuf-runtime-protoimpl",
         "soong-cmd-find_input_delta-proto",
         "soong-cmd-find_input_delta-proto_internal",
+        "android-archive-zip",
         "blueprint-pathtools",
     ],
     srcs: [
diff --git a/cmd/find_input_delta/find_input_delta_lib/file_list.go b/cmd/find_input_delta/find_input_delta_lib/file_list.go
index 23337ad..01242a0 100644
--- a/cmd/find_input_delta/find_input_delta_lib/file_list.go
+++ b/cmd/find_input_delta/find_input_delta_lib/file_list.go
@@ -15,10 +15,15 @@
 package find_input_delta_lib
 
 import (
+	"fmt"
 	"io"
+	"os"
+	"path/filepath"
+	"slices"
 	"text/template"
 
 	fid_exp "android/soong/cmd/find_input_delta/find_input_delta_proto"
+	"google.golang.org/protobuf/encoding/protowire"
 	"google.golang.org/protobuf/proto"
 )
 
@@ -47,28 +52,148 @@
 
 	// The modified files
 	Changes []FileList
+
+	// Map of file_extension:counts
+	ExtCountMap map[string]*FileCounts
+
+	// Total number of added/changed/deleted files.
+	TotalDelta uint32
 }
 
-func (fl FileList) Marshal() (*fid_exp.FileList, error) {
+// The maximum number of files that will be recorded by name.
+var MaxFilesRecorded uint32 = 50
+
+type FileCounts struct {
+	Additions uint32
+	Deletions uint32
+	Changes   uint32
+}
+
+func FileListFactory(name string) *FileList {
+	return &FileList{
+		Name:        name,
+		ExtCountMap: make(map[string]*FileCounts),
+	}
+}
+
+func (fl *FileList) addFile(name string) {
+	fl.Additions = append(fl.Additions, name)
+	fl.TotalDelta += 1
+	ext := filepath.Ext(name)
+	if _, ok := fl.ExtCountMap[ext]; !ok {
+		fl.ExtCountMap[ext] = &FileCounts{}
+	}
+	fl.ExtCountMap[ext].Additions += 1
+}
+
+func (fl *FileList) deleteFile(name string) {
+	fl.Deletions = append(fl.Deletions, name)
+	fl.TotalDelta += 1
+	ext := filepath.Ext(name)
+	if _, ok := fl.ExtCountMap[ext]; !ok {
+		fl.ExtCountMap[ext] = &FileCounts{}
+	}
+	fl.ExtCountMap[ext].Deletions += 1
+}
+
+func (fl *FileList) changeFile(name string, ch *FileList) {
+	fl.Changes = append(fl.Changes, *ch)
+	fl.TotalDelta += 1
+	ext := filepath.Ext(name)
+	if _, ok := fl.ExtCountMap[ext]; !ok {
+		fl.ExtCountMap[ext] = &FileCounts{}
+	}
+	fl.ExtCountMap[ext].Changes += 1
+}
+
+func (fl FileList) ToProto() (*fid_exp.FileList, error) {
+	var count uint32
+	return fl.toProto(&count)
+}
+
+func (fl FileList) toProto(count *uint32) (*fid_exp.FileList, error) {
 	ret := &fid_exp.FileList{
 		Name: proto.String(fl.Name),
 	}
-	if len(fl.Additions) > 0 {
-		ret.Additions = fl.Additions
+	for _, a := range fl.Additions {
+		if *count >= MaxFilesRecorded {
+			break
+		}
+		ret.Additions = append(ret.Additions, a)
+		*count += 1
 	}
 	for _, ch := range fl.Changes {
-		change, err := ch.Marshal()
-		if err != nil {
-			return nil, err
+		if *count >= MaxFilesRecorded {
+			break
+		} else {
+			// Pre-increment to limit what the call adds.
+			*count += 1
+			change, err := ch.toProto(count)
+			if err != nil {
+				return nil, err
+			}
+			ret.Changes = append(ret.Changes, change)
 		}
-		ret.Changes = append(ret.Changes, change)
 	}
-	if len(fl.Deletions) > 0 {
-		ret.Deletions = fl.Deletions
+	for _, d := range fl.Deletions {
+		if *count >= MaxFilesRecorded {
+			break
+		}
+		ret.Deletions = append(ret.Deletions, d)
+	}
+	ret.TotalDelta = proto.Uint32(*count)
+	exts := []string{}
+	for k := range fl.ExtCountMap {
+		exts = append(exts, k)
+	}
+	slices.Sort(exts)
+	for _, k := range exts {
+		v := fl.ExtCountMap[k]
+		ret.Counts = append(ret.Counts, &fid_exp.FileCount{
+			Extension:     proto.String(k),
+			Additions:     proto.Uint32(v.Additions),
+			Deletions:     proto.Uint32(v.Deletions),
+			Modifications: proto.Uint32(v.Changes),
+		})
 	}
 	return ret, nil
 }
 
+func (fl FileList) SendMetrics(path string) error {
+	if path == "" {
+		return fmt.Errorf("No path given")
+	}
+	message, err := fl.ToProto()
+	if err != nil {
+		return err
+	}
+
+	// Marshal the message wrapped in SoongCombinedMetrics.
+	data := protowire.AppendVarint(
+		[]byte{},
+		protowire.EncodeTag(
+			protowire.Number(fid_exp.FieldNumbers_FIELD_NUMBERS_FILE_LIST),
+			protowire.BytesType))
+	size := uint64(proto.Size(message))
+	data = protowire.AppendVarint(data, size)
+	data, err = proto.MarshalOptions{UseCachedSize: true}.MarshalAppend(data, message)
+	if err != nil {
+		return err
+	}
+
+	out, err := os.Create(path)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if err := out.Close(); err != nil {
+			fmt.Fprintf(os.Stderr, "Failed to close %s: %v\n", path, err)
+		}
+	}()
+	_, err = out.Write(data)
+	return err
+}
+
 func (fl FileList) Format(wr io.Writer, format string) error {
 	tmpl, err := template.New("filelist").Parse(format)
 	if err != nil {
diff --git a/cmd/find_input_delta/find_input_delta_lib/fs.go b/cmd/find_input_delta/find_input_delta_lib/fs.go
index 4a83ed7..09a8aa6 100644
--- a/cmd/find_input_delta/find_input_delta_lib/fs.go
+++ b/cmd/find_input_delta/find_input_delta_lib/fs.go
@@ -15,7 +15,6 @@
 package find_input_delta_lib
 
 import (
-	"io"
 	"io/fs"
 	"os"
 )
@@ -30,14 +29,6 @@
 	ReadFile(path string) ([]byte, error)
 }
 
-type file interface {
-	io.Closer
-	io.Reader
-	io.ReaderAt
-	io.Seeker
-	Stat() (os.FileInfo, error)
-}
-
 // osFS implements fileSystem using the local disk.
 type osFS struct{}
 
diff --git a/cmd/find_input_delta/find_input_delta_lib/internal_state.go b/cmd/find_input_delta/find_input_delta_lib/internal_state.go
index b2ff8c7..f0242b7 100644
--- a/cmd/find_input_delta/find_input_delta_lib/internal_state.go
+++ b/cmd/find_input_delta/find_input_delta_lib/internal_state.go
@@ -18,9 +18,11 @@
 	"errors"
 	"fmt"
 	"io/fs"
+	"path/filepath"
 	"slices"
 
 	fid_proto "android/soong/cmd/find_input_delta/find_input_delta_proto_internal"
+	"android/soong/third_party/zip"
 	"github.com/google/blueprint/pathtools"
 	"google.golang.org/protobuf/proto"
 )
@@ -57,6 +59,7 @@
 			// If we ever have an easy hash, assign it here.
 		}
 		if inspect_contents {
+			// NOTE: When we find it useful, we can parallelize the file inspection for speed.
 			contents, err := InspectFileContents(input)
 			if err != nil {
 				return ret, err
@@ -73,9 +76,30 @@
 // Inspect the file and extract the state of the elements in the archive.
 // If this is not an archive of some sort, nil is returned.
 func InspectFileContents(name string) ([]*fid_proto.PartialCompileInput, error) {
-	// TODO: Actually inspect the contents.
-	fmt.Printf("inspecting contents for %s\n", name)
-	return nil, nil
+	switch filepath.Ext(name) {
+	case ".jar", ".apex", ".apk":
+		return inspectZipFileContents(name)
+	default:
+		return nil, nil
+	}
+}
+
+func inspectZipFileContents(name string) ([]*fid_proto.PartialCompileInput, error) {
+	rc, err := zip.OpenReader(name)
+	if err != nil {
+		return nil, err
+	}
+	ret := []*fid_proto.PartialCompileInput{}
+	for _, v := range rc.File {
+		pci := &fid_proto.PartialCompileInput{
+			Name:      proto.String(v.Name),
+			MtimeNsec: proto.Int64(v.ModTime().UnixNano()),
+			Hash:      proto.String(fmt.Sprintf("%08x", v.CRC32)),
+		}
+		ret = append(ret, pci)
+		// We do not support nested inspection.
+	}
+	return ret, nil
 }
 
 func WriteState(s *fid_proto.PartialCompileInputs, path string) error {
@@ -91,9 +115,7 @@
 }
 
 func CompareInputFiles(prior, other []*fid_proto.PartialCompileInput, name string) *FileList {
-	fl := &FileList{
-		Name: name,
-	}
+	fl := FileListFactory(name)
 	PriorMap := make(map[string]*fid_proto.PartialCompileInput, len(prior))
 	// We know that the lists are properly sorted, so we can simply compare them.
 	for _, v := range prior {
@@ -105,17 +127,17 @@
 		otherMap[name] = v
 		if _, ok := PriorMap[name]; !ok {
 			// Added file
-			fl.Additions = append(fl.Additions, name)
+			fl.addFile(name)
 		} else if !proto.Equal(PriorMap[name], v) {
 			// Changed file
-			fl.Changes = append(fl.Changes, *CompareInputFiles(PriorMap[name].GetContents(), v.GetContents(), name))
+			fl.changeFile(name, CompareInputFiles(PriorMap[name].GetContents(), v.GetContents(), name))
 		}
 	}
 	for _, v := range prior {
 		name := v.GetName()
 		if _, ok := otherMap[name]; !ok {
 			// Deleted file
-			fl.Deletions = append(fl.Deletions, name)
+			fl.deleteFile(name)
 		}
 	}
 	return fl
diff --git a/cmd/find_input_delta/find_input_delta_lib/internal_state_test.go b/cmd/find_input_delta/find_input_delta_lib/internal_state_test.go
index 20b8efa..e69424c 100644
--- a/cmd/find_input_delta/find_input_delta_lib/internal_state_test.go
+++ b/cmd/find_input_delta/find_input_delta_lib/internal_state_test.go
@@ -199,7 +199,7 @@
 			},
 		},
 		{
-			Name:   "one of each",
+			Name:   "one each add modify delete",
 			Target: "foo",
 			Prior: &fid_proto.PartialCompileInputs{
 				InputFiles: []*fid_proto.PartialCompileInput{
@@ -222,11 +222,40 @@
 				Deletions: []string{"file2"},
 			},
 		},
+		{
+			Name:   "interior one each add modify delete",
+			Target: "bar",
+			Prior: &fid_proto.PartialCompileInputs{
+				InputFiles: []*fid_proto.PartialCompileInput{
+					protoFile("file1", 405, "", []*fid_proto.PartialCompileInput{
+						protoFile("innerC", 400, "crc32:11111111", nil),
+						protoFile("innerD", 400, "crc32:44444444", nil),
+					}),
+				},
+			},
+			New: &fid_proto.PartialCompileInputs{
+				InputFiles: []*fid_proto.PartialCompileInput{
+					protoFile("file1", 505, "", []*fid_proto.PartialCompileInput{
+						protoFile("innerA", 400, "crc32:55555555", nil),
+						protoFile("innerC", 500, "crc32:66666666", nil),
+					}),
+				},
+			},
+			Expected: &FileList{
+				Name: "bar",
+				Changes: []FileList{FileList{
+					Name:      "file1",
+					Additions: []string{"innerA"},
+					Changes:   []FileList{FileList{Name: "innerC"}},
+					Deletions: []string{"innerD"},
+				}},
+			},
+		},
 	}
 	for _, tc := range testCases {
 		actual := CompareInternalState(tc.Prior, tc.New, tc.Target)
 		if !tc.Expected.Equal(actual) {
-			t.Errorf("%s: expected %q, actual %q", tc.Name, tc.Expected, actual)
+			t.Errorf("%s: expected %v, actual %v", tc.Name, tc.Expected, actual)
 		}
 	}
 }
diff --git a/cmd/find_input_delta/find_input_delta_proto/file_list.pb.go b/cmd/find_input_delta/find_input_delta_proto/file_list.pb.go
index 648ef22..745de2d 100644
--- a/cmd/find_input_delta/find_input_delta_proto/file_list.pb.go
+++ b/cmd/find_input_delta/find_input_delta_proto/file_list.pb.go
@@ -19,7 +19,7 @@
 // 	protoc        v3.21.12
 // source: file_list.proto
 
-package proto
+package find_input_delta_proto
 
 import (
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
@@ -35,6 +35,62 @@
 	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
 )
 
+type FieldNumbers int32
+
+const (
+	FieldNumbers_FIELD_NUMBERS_UNSPECIFIED FieldNumbers = 0
+	FieldNumbers_FIELD_NUMBERS_FILE_LIST   FieldNumbers = 1
+)
+
+// Enum value maps for FieldNumbers.
+var (
+	FieldNumbers_name = map[int32]string{
+		0: "FIELD_NUMBERS_UNSPECIFIED",
+		1: "FIELD_NUMBERS_FILE_LIST",
+	}
+	FieldNumbers_value = map[string]int32{
+		"FIELD_NUMBERS_UNSPECIFIED": 0,
+		"FIELD_NUMBERS_FILE_LIST":   1,
+	}
+)
+
+func (x FieldNumbers) Enum() *FieldNumbers {
+	p := new(FieldNumbers)
+	*p = x
+	return p
+}
+
+func (x FieldNumbers) String() string {
+	return protoimpl.X.EnumStringOf(x.Descriptor(), protoreflect.EnumNumber(x))
+}
+
+func (FieldNumbers) Descriptor() protoreflect.EnumDescriptor {
+	return file_file_list_proto_enumTypes[0].Descriptor()
+}
+
+func (FieldNumbers) Type() protoreflect.EnumType {
+	return &file_file_list_proto_enumTypes[0]
+}
+
+func (x FieldNumbers) Number() protoreflect.EnumNumber {
+	return protoreflect.EnumNumber(x)
+}
+
+// Deprecated: Do not use.
+func (x *FieldNumbers) UnmarshalJSON(b []byte) error {
+	num, err := protoimpl.X.UnmarshalJSONEnum(x.Descriptor(), b)
+	if err != nil {
+		return err
+	}
+	*x = FieldNumbers(num)
+	return nil
+}
+
+// Deprecated: Use FieldNumbers.Descriptor instead.
+func (FieldNumbers) EnumDescriptor() ([]byte, []int) {
+	return file_file_list_proto_rawDescGZIP(), []int{0}
+}
+
 type FileList struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache
@@ -46,10 +102,14 @@
 	Name *string `protobuf:"bytes,1,opt,name=name" json:"name,omitempty"`
 	// The added files.
 	Additions []string `protobuf:"bytes,2,rep,name=additions" json:"additions,omitempty"`
-	// The deleted files.
-	Deletions []string `protobuf:"bytes,3,rep,name=deletions" json:"deletions,omitempty"`
 	// The changed files.
-	Changes []*FileList `protobuf:"bytes,4,rep,name=changes" json:"changes,omitempty"`
+	Changes []*FileList `protobuf:"bytes,3,rep,name=changes" json:"changes,omitempty"`
+	// The deleted files.
+	Deletions []string `protobuf:"bytes,4,rep,name=deletions" json:"deletions,omitempty"`
+	// Count of files added/changed/deleted.
+	TotalDelta *uint32 `protobuf:"varint,5,opt,name=total_delta,json=totalDelta" json:"total_delta,omitempty"`
+	// Counts by extension.
+	Counts []*FileCount `protobuf:"bytes,6,rep,name=counts" json:"counts,omitempty"`
 }
 
 func (x *FileList) Reset() {
@@ -98,6 +158,13 @@
 	return nil
 }
 
+func (x *FileList) GetChanges() []*FileList {
+	if x != nil {
+		return x.Changes
+	}
+	return nil
+}
+
 func (x *FileList) GetDeletions() []string {
 	if x != nil {
 		return x.Deletions
@@ -105,32 +172,135 @@
 	return nil
 }
 
-func (x *FileList) GetChanges() []*FileList {
+func (x *FileList) GetTotalDelta() uint32 {
+	if x != nil && x.TotalDelta != nil {
+		return *x.TotalDelta
+	}
+	return 0
+}
+
+func (x *FileList) GetCounts() []*FileCount {
 	if x != nil {
-		return x.Changes
+		return x.Counts
 	}
 	return nil
 }
 
+type FileCount struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	// The file extension
+	Extension *string `protobuf:"bytes,1,opt,name=extension" json:"extension,omitempty"`
+	// Number of added files with this extension.
+	Additions *uint32 `protobuf:"varint,2,opt,name=additions" json:"additions,omitempty"`
+	// Number of modified files with this extension.
+	Modifications *uint32 `protobuf:"varint,3,opt,name=modifications" json:"modifications,omitempty"`
+	// Number of deleted files with this extension.
+	Deletions *uint32 `protobuf:"varint,4,opt,name=deletions" json:"deletions,omitempty"`
+}
+
+func (x *FileCount) Reset() {
+	*x = FileCount{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_file_list_proto_msgTypes[1]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *FileCount) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*FileCount) ProtoMessage() {}
+
+func (x *FileCount) ProtoReflect() protoreflect.Message {
+	mi := &file_file_list_proto_msgTypes[1]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use FileCount.ProtoReflect.Descriptor instead.
+func (*FileCount) Descriptor() ([]byte, []int) {
+	return file_file_list_proto_rawDescGZIP(), []int{1}
+}
+
+func (x *FileCount) GetExtension() string {
+	if x != nil && x.Extension != nil {
+		return *x.Extension
+	}
+	return ""
+}
+
+func (x *FileCount) GetAdditions() uint32 {
+	if x != nil && x.Additions != nil {
+		return *x.Additions
+	}
+	return 0
+}
+
+func (x *FileCount) GetModifications() uint32 {
+	if x != nil && x.Modifications != nil {
+		return *x.Modifications
+	}
+	return 0
+}
+
+func (x *FileCount) GetDeletions() uint32 {
+	if x != nil && x.Deletions != nil {
+		return *x.Deletions
+	}
+	return 0
+}
+
 var File_file_list_proto protoreflect.FileDescriptor
 
 var file_file_list_proto_rawDesc = []byte{
 	0x0a, 0x0f, 0x66, 0x69, 0x6c, 0x65, 0x5f, 0x6c, 0x69, 0x73, 0x74, 0x2e, 0x70, 0x72, 0x6f, 0x74,
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+	0x74, 0x5f, 0x64, 0x65, 0x6c, 0x74, 0x61, 0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f,
 }
 
 var (
@@ -145,17 +315,21 @@
 	return file_file_list_proto_rawDescData
 }
 
-var file_file_list_proto_msgTypes = make([]protoimpl.MessageInfo, 1)
+var file_file_list_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
+var file_file_list_proto_msgTypes = make([]protoimpl.MessageInfo, 2)
 var file_file_list_proto_goTypes = []interface{}{
-	(*FileList)(nil), // 0: android.find_input_delta_proto.FileList
+	(FieldNumbers)(0), // 0: android.find_input_delta_proto.FieldNumbers
+	(*FileList)(nil),  // 1: android.find_input_delta_proto.FileList
+	(*FileCount)(nil), // 2: android.find_input_delta_proto.FileCount
 }
 var file_file_list_proto_depIdxs = []int32{
-	0, // 0: android.find_input_delta_proto.FileList.changes:type_name -> android.find_input_delta_proto.FileList
-	1, // [1:1] is the sub-list for method output_type
-	1, // [1:1] is the sub-list for method input_type
-	1, // [1:1] is the sub-list for extension type_name
-	1, // [1:1] is the sub-list for extension extendee
-	0, // [0:1] is the sub-list for field type_name
+	1, // 0: android.find_input_delta_proto.FileList.changes:type_name -> android.find_input_delta_proto.FileList
+	2, // 1: android.find_input_delta_proto.FileList.counts:type_name -> android.find_input_delta_proto.FileCount
+	2, // [2:2] is the sub-list for method output_type
+	2, // [2:2] is the sub-list for method input_type
+	2, // [2:2] is the sub-list for extension type_name
+	2, // [2:2] is the sub-list for extension extendee
+	0, // [0:2] is the sub-list for field type_name
 }
 
 func init() { file_file_list_proto_init() }
@@ -176,19 +350,32 @@
 				return nil
 			}
 		}
+		file_file_list_proto_msgTypes[1].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*FileCount); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
 	}
 	type x struct{}
 	out := protoimpl.TypeBuilder{
 		File: protoimpl.DescBuilder{
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_file_list_proto_rawDesc,
-			NumEnums:      0,
-			NumMessages:   1,
+			NumEnums:      1,
+			NumMessages:   2,
 			NumExtensions: 0,
 			NumServices:   0,
 		},
 		GoTypes:           file_file_list_proto_goTypes,
 		DependencyIndexes: file_file_list_proto_depIdxs,
+		EnumInfos:         file_file_list_proto_enumTypes,
 		MessageInfos:      file_file_list_proto_msgTypes,
 	}.Build()
 	File_file_list_proto = out.File
diff --git a/cmd/find_input_delta/find_input_delta_proto/file_list.proto b/cmd/find_input_delta/find_input_delta_proto/file_list.proto
index d7faca9..7180358 100644
--- a/cmd/find_input_delta/find_input_delta_proto/file_list.proto
+++ b/cmd/find_input_delta/find_input_delta_proto/file_list.proto
@@ -15,7 +15,12 @@
 
 syntax = "proto2";
 package android.find_input_delta_proto;
-option go_package = "android/soong/find_input_delta/proto";
+option go_package = "android/soong/cmd/find_input_delta/find_input_delta_proto";
+
+enum FieldNumbers {
+  FIELD_NUMBERS_UNSPECIFIED = 0;
+  FIELD_NUMBERS_FILE_LIST = 1;
+}
 
 message FileList {
   // The name of the file.
@@ -26,9 +31,29 @@
   // The added files.
   repeated string additions = 2;
 
-  // The deleted files.
-  repeated string deletions = 3;
-
   // The changed files.
-  repeated FileList changes = 4;
+  repeated FileList changes = 3;
+
+  // The deleted files.
+  repeated string deletions = 4;
+
+  // Count of files added/changed/deleted.
+  optional uint32 total_delta = 5;
+
+  // Counts by extension.
+  repeated FileCount counts = 6;
+}
+
+message FileCount {
+  // The file extension
+  optional string extension = 1;
+
+  // Number of added files with this extension.
+  optional uint32 additions = 2;
+
+  // Number of modified files with this extension.
+  optional uint32 modifications = 3;
+
+  // Number of deleted files with this extension.
+  optional uint32 deletions = 4;
 }
diff --git a/cmd/find_input_delta/find_input_delta_proto_internal/internal_state.pb.go b/cmd/find_input_delta/find_input_delta_proto_internal/internal_state.pb.go
index 2229a32..c5b048b 100644
--- a/cmd/find_input_delta/find_input_delta_proto_internal/internal_state.pb.go
+++ b/cmd/find_input_delta/find_input_delta_proto_internal/internal_state.pb.go
@@ -19,7 +19,7 @@
 // 	protoc        v3.21.12
 // source: internal_state.proto
 
-package proto
+package find_input_delta_proto_internal
 
 import (
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
@@ -94,7 +94,7 @@
 	Name *string `protobuf:"bytes,1,opt,name=name" json:"name,omitempty"`
 	// The timestamp of the file in (Unix) nanoseconds.
 	MtimeNsec *int64 `protobuf:"varint,2,opt,name=mtime_nsec,json=mtimeNsec" json:"mtime_nsec,omitempty"`
-	// The hash of the file, in the form ‘{HASHNAME}:{VALUE}’
+	// The hash of the file.  For crc32 hashes, this will be 8 hex digits.
 	Hash *string `protobuf:"bytes,3,opt,name=hash" json:"hash,omitempty"`
 	// Contents of the file, if the file was inspected (such as jar files, etc).
 	Contents []*PartialCompileInput `protobuf:"bytes,4,rep,name=contents" json:"contents,omitempty"`
@@ -164,29 +164,33 @@
 
 var file_internal_state_proto_rawDesc = []byte{
 	0x0a, 0x14, 0x69, 0x6e, 0x74, 0x65, 0x72, 0x6e, 0x61, 0x6c, 0x5f, 0x73, 0x74, 0x61, 0x74, 0x65,
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+	0x6c,
 }
 
 var (
@@ -203,12 +207,12 @@
 
 var file_internal_state_proto_msgTypes = make([]protoimpl.MessageInfo, 2)
 var file_internal_state_proto_goTypes = []interface{}{
-	(*PartialCompileInputs)(nil), // 0: android.find_input_delta_proto.PartialCompileInputs
-	(*PartialCompileInput)(nil),  // 1: android.find_input_delta_proto.PartialCompileInput
+	(*PartialCompileInputs)(nil), // 0: android.find_input_delta_proto_internal.PartialCompileInputs
+	(*PartialCompileInput)(nil),  // 1: android.find_input_delta_proto_internal.PartialCompileInput
 }
 var file_internal_state_proto_depIdxs = []int32{
-	1, // 0: android.find_input_delta_proto.PartialCompileInputs.input_files:type_name -> android.find_input_delta_proto.PartialCompileInput
-	1, // 1: android.find_input_delta_proto.PartialCompileInput.contents:type_name -> android.find_input_delta_proto.PartialCompileInput
+	1, // 0: android.find_input_delta_proto_internal.PartialCompileInputs.input_files:type_name -> android.find_input_delta_proto_internal.PartialCompileInput
+	1, // 1: android.find_input_delta_proto_internal.PartialCompileInput.contents:type_name -> android.find_input_delta_proto_internal.PartialCompileInput
 	2, // [2:2] is the sub-list for method output_type
 	2, // [2:2] is the sub-list for method input_type
 	2, // [2:2] is the sub-list for extension type_name
diff --git a/cmd/find_input_delta/find_input_delta_proto_internal/internal_state.proto b/cmd/find_input_delta/find_input_delta_proto_internal/internal_state.proto
index 113fc64..54c90cc 100644
--- a/cmd/find_input_delta/find_input_delta_proto_internal/internal_state.proto
+++ b/cmd/find_input_delta/find_input_delta_proto_internal/internal_state.proto
@@ -14,8 +14,8 @@
 // limitations under the License.
 
 syntax = "proto2";
-package android.find_input_delta_proto;
-option go_package = "android/soong/find_input_delta/proto";
+package android.find_input_delta_proto_internal;
+option go_package = "android/soong/find_input_delta/find_input_delta_proto_internal";
 
 // The state of all inputs.
 message PartialCompileInputs {
@@ -31,7 +31,7 @@
   // The timestamp of the file in (Unix) nanoseconds.
   optional int64 mtime_nsec = 2;
 
-  // The hash of the file, in the form ‘{HASHNAME}:{VALUE}’
+  // The hash of the file.  For crc32 hashes, this will be 8 hex digits.
   optional string hash = 3;
 
   // Contents of the file, if the file was inspected (such as jar files, etc).
diff --git a/ui/metrics/Android.bp b/ui/metrics/Android.bp
index 77871fc..591e3cc 100644
--- a/ui/metrics/Android.bp
+++ b/ui/metrics/Android.bp
@@ -26,6 +26,7 @@
         "soong-ui-metrics_proto",
         "soong-ui-mk_metrics_proto",
         "soong-shared",
+        "soong-ui-metrics_combined_proto",
     ],
     srcs: [
         "hostinfo.go",
@@ -63,6 +64,19 @@
 }
 
 bootstrap_go_package {
+    name: "soong-ui-metrics_combined_proto",
+    pkgPath: "android/soong/ui/metrics/combined_metrics_proto",
+    deps: [
+        "golang-protobuf-reflect-protoreflect",
+        "golang-protobuf-runtime-protoimpl",
+        "soong-cmd-find_input_delta-proto",
+    ],
+    srcs: [
+        "metrics_proto/metrics.pb.go",
+    ],
+}
+
+bootstrap_go_package {
     name: "soong-ui-metrics_upload_proto",
     pkgPath: "android/soong/ui/metrics/upload_proto",
     deps: [
diff --git a/ui/metrics/metrics_proto/combined_metrics.pb.go b/ui/metrics/metrics_proto/combined_metrics.pb.go
new file mode 100644
index 0000000..f49d64d
--- /dev/null
+++ b/ui/metrics/metrics_proto/combined_metrics.pb.go
@@ -0,0 +1,239 @@
+// 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.
+
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// versions:
+// 	protoc-gen-go v1.33.0
+// 	protoc        v3.21.12
+// source: combined_metrics.proto
+
+package metrics_proto
+
+import (
+	find_input_delta_proto "android/soong/cmd/find_input_delta/find_input_delta_proto"
+	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
+	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
+	reflect "reflect"
+	sync "sync"
+)
+
+const (
+	// Verify that this generated code is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion)
+	// Verify that runtime/protoimpl is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
+)
+
+// These field numbers are also found in the inner message declarations.
+// We verify that the values are the same, and that every enum value is checked
+// in combined_metrics_test.go.
+// Do not change this enum without also updating:
+//   - the submessage's .proto file
+//   - combined_metrics_test.go
+type FieldNumbers int32
+
+const (
+	FieldNumbers_FIELD_NUMBERS_UNSPECIFIED FieldNumbers = 0
+	FieldNumbers_FIELD_NUMBERS_FILE_LIST   FieldNumbers = 1
+)
+
+// Enum value maps for FieldNumbers.
+var (
+	FieldNumbers_name = map[int32]string{
+		0: "FIELD_NUMBERS_UNSPECIFIED",
+		1: "FIELD_NUMBERS_FILE_LIST",
+	}
+	FieldNumbers_value = map[string]int32{
+		"FIELD_NUMBERS_UNSPECIFIED": 0,
+		"FIELD_NUMBERS_FILE_LIST":   1,
+	}
+)
+
+func (x FieldNumbers) Enum() *FieldNumbers {
+	p := new(FieldNumbers)
+	*p = x
+	return p
+}
+
+func (x FieldNumbers) String() string {
+	return protoimpl.X.EnumStringOf(x.Descriptor(), protoreflect.EnumNumber(x))
+}
+
+func (FieldNumbers) Descriptor() protoreflect.EnumDescriptor {
+	return file_combined_metrics_proto_enumTypes[0].Descriptor()
+}
+
+func (FieldNumbers) Type() protoreflect.EnumType {
+	return &file_combined_metrics_proto_enumTypes[0]
+}
+
+func (x FieldNumbers) Number() protoreflect.EnumNumber {
+	return protoreflect.EnumNumber(x)
+}
+
+// Deprecated: Do not use.
+func (x *FieldNumbers) UnmarshalJSON(b []byte) error {
+	num, err := protoimpl.X.UnmarshalJSONEnum(x.Descriptor(), b)
+	if err != nil {
+		return err
+	}
+	*x = FieldNumbers(num)
+	return nil
+}
+
+// Deprecated: Use FieldNumbers.Descriptor instead.
+func (FieldNumbers) EnumDescriptor() ([]byte, []int) {
+	return file_combined_metrics_proto_rawDescGZIP(), []int{0}
+}
+
+type SoongCombinedMetrics struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	// cmd/find_input_delta/find_input_delta_proto.FileList
+	FileList *find_input_delta_proto.FileList `protobuf:"bytes,1,opt,name=file_list,json=fileList" json:"file_list,omitempty"`
+}
+
+func (x *SoongCombinedMetrics) Reset() {
+	*x = SoongCombinedMetrics{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_combined_metrics_proto_msgTypes[0]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *SoongCombinedMetrics) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*SoongCombinedMetrics) ProtoMessage() {}
+
+func (x *SoongCombinedMetrics) ProtoReflect() protoreflect.Message {
+	mi := &file_combined_metrics_proto_msgTypes[0]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use SoongCombinedMetrics.ProtoReflect.Descriptor instead.
+func (*SoongCombinedMetrics) Descriptor() ([]byte, []int) {
+	return file_combined_metrics_proto_rawDescGZIP(), []int{0}
+}
+
+func (x *SoongCombinedMetrics) GetFileList() *find_input_delta_proto.FileList {
+	if x != nil {
+		return x.FileList
+	}
+	return nil
+}
+
+var File_combined_metrics_proto protoreflect.FileDescriptor
+
+var file_combined_metrics_proto_rawDesc = []byte{
+	0x0a, 0x16, 0x63, 0x6f, 0x6d, 0x62, 0x69, 0x6e, 0x65, 0x64, 0x5f, 0x6d, 0x65, 0x74, 0x72, 0x69,
+	0x63, 0x73, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x12, 0x13, 0x73, 0x6f, 0x6f, 0x6e, 0x67, 0x5f,
+	0x62, 0x75, 0x69, 0x6c, 0x64, 0x5f, 0x6d, 0x65, 0x74, 0x72, 0x69, 0x63, 0x73, 0x1a, 0x3b, 0x63,
+	0x6d, 0x64, 0x2f, 0x66, 0x69, 0x6e, 0x64, 0x5f, 0x69, 0x6e, 0x70, 0x75, 0x74, 0x5f, 0x64, 0x65,
+	0x6c, 0x74, 0x61, 0x2f, 0x66, 0x69, 0x6e, 0x64, 0x5f, 0x69, 0x6e, 0x70, 0x75, 0x74, 0x5f, 0x64,
+	0x65, 0x6c, 0x74, 0x61, 0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x2f, 0x66, 0x69, 0x6c, 0x65, 0x5f,
+	0x6c, 0x69, 0x73, 0x74, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x22, 0x5d, 0x0a, 0x14, 0x53, 0x6f,
+	0x6f, 0x6e, 0x67, 0x43, 0x6f, 0x6d, 0x62, 0x69, 0x6e, 0x65, 0x64, 0x4d, 0x65, 0x74, 0x72, 0x69,
+	0x63, 0x73, 0x12, 0x45, 0x0a, 0x09, 0x66, 0x69, 0x6c, 0x65, 0x5f, 0x6c, 0x69, 0x73, 0x74, 0x18,
+	0x01, 0x20, 0x01, 0x28, 0x0b, 0x32, 0x28, 0x2e, 0x61, 0x6e, 0x64, 0x72, 0x6f, 0x69, 0x64, 0x2e,
+	0x66, 0x69, 0x6e, 0x64, 0x5f, 0x69, 0x6e, 0x70, 0x75, 0x74, 0x5f, 0x64, 0x65, 0x6c, 0x74, 0x61,
+	0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x2e, 0x46, 0x69, 0x6c, 0x65, 0x4c, 0x69, 0x73, 0x74, 0x52,
+	0x08, 0x66, 0x69, 0x6c, 0x65, 0x4c, 0x69, 0x73, 0x74, 0x2a, 0x4a, 0x0a, 0x0c, 0x46, 0x69, 0x65,
+	0x6c, 0x64, 0x4e, 0x75, 0x6d, 0x62, 0x65, 0x72, 0x73, 0x12, 0x1d, 0x0a, 0x19, 0x46, 0x49, 0x45,
+	0x4c, 0x44, 0x5f, 0x4e, 0x55, 0x4d, 0x42, 0x45, 0x52, 0x53, 0x5f, 0x55, 0x4e, 0x53, 0x50, 0x45,
+	0x43, 0x49, 0x46, 0x49, 0x45, 0x44, 0x10, 0x00, 0x12, 0x1b, 0x0a, 0x17, 0x46, 0x49, 0x45, 0x4c,
+	0x44, 0x5f, 0x4e, 0x55, 0x4d, 0x42, 0x45, 0x52, 0x53, 0x5f, 0x46, 0x49, 0x4c, 0x45, 0x5f, 0x4c,
+	0x49, 0x53, 0x54, 0x10, 0x01, 0x42, 0x28, 0x5a, 0x26, 0x61, 0x6e, 0x64, 0x72, 0x6f, 0x69, 0x64,
+	0x2f, 0x73, 0x6f, 0x6f, 0x6e, 0x67, 0x2f, 0x75, 0x69, 0x2f, 0x6d, 0x65, 0x74, 0x72, 0x69, 0x63,
+	0x73, 0x2f, 0x6d, 0x65, 0x74, 0x72, 0x69, 0x63, 0x73, 0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f,
+}
+
+var (
+	file_combined_metrics_proto_rawDescOnce sync.Once
+	file_combined_metrics_proto_rawDescData = file_combined_metrics_proto_rawDesc
+)
+
+func file_combined_metrics_proto_rawDescGZIP() []byte {
+	file_combined_metrics_proto_rawDescOnce.Do(func() {
+		file_combined_metrics_proto_rawDescData = protoimpl.X.CompressGZIP(file_combined_metrics_proto_rawDescData)
+	})
+	return file_combined_metrics_proto_rawDescData
+}
+
+var file_combined_metrics_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
+var file_combined_metrics_proto_msgTypes = make([]protoimpl.MessageInfo, 1)
+var file_combined_metrics_proto_goTypes = []interface{}{
+	(FieldNumbers)(0),                       // 0: soong_build_metrics.FieldNumbers
+	(*SoongCombinedMetrics)(nil),            // 1: soong_build_metrics.SoongCombinedMetrics
+	(*find_input_delta_proto.FileList)(nil), // 2: android.find_input_delta_proto.FileList
+}
+var file_combined_metrics_proto_depIdxs = []int32{
+	2, // 0: soong_build_metrics.SoongCombinedMetrics.file_list:type_name -> android.find_input_delta_proto.FileList
+	1, // [1:1] is the sub-list for method output_type
+	1, // [1:1] is the sub-list for method input_type
+	1, // [1:1] is the sub-list for extension type_name
+	1, // [1:1] is the sub-list for extension extendee
+	0, // [0:1] is the sub-list for field type_name
+}
+
+func init() { file_combined_metrics_proto_init() }
+func file_combined_metrics_proto_init() {
+	if File_combined_metrics_proto != nil {
+		return
+	}
+	if !protoimpl.UnsafeEnabled {
+		file_combined_metrics_proto_msgTypes[0].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*SoongCombinedMetrics); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+	}
+	type x struct{}
+	out := protoimpl.TypeBuilder{
+		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
+			RawDescriptor: file_combined_metrics_proto_rawDesc,
+			NumEnums:      1,
+			NumMessages:   1,
+			NumExtensions: 0,
+			NumServices:   0,
+		},
+		GoTypes:           file_combined_metrics_proto_goTypes,
+		DependencyIndexes: file_combined_metrics_proto_depIdxs,
+		EnumInfos:         file_combined_metrics_proto_enumTypes,
+		MessageInfos:      file_combined_metrics_proto_msgTypes,
+	}.Build()
+	File_combined_metrics_proto = out.File
+	file_combined_metrics_proto_rawDesc = nil
+	file_combined_metrics_proto_goTypes = nil
+	file_combined_metrics_proto_depIdxs = nil
+}
diff --git a/ui/metrics/metrics_proto/combined_metrics.proto b/ui/metrics/metrics_proto/combined_metrics.proto
new file mode 100644
index 0000000..3cd9a53
--- /dev/null
+++ b/ui/metrics/metrics_proto/combined_metrics.proto
@@ -0,0 +1,36 @@
+// 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.
+
+syntax = "proto2";
+
+package soong_build_metrics;
+option go_package = "android/soong/ui/metrics/metrics_proto";
+
+import "cmd/find_input_delta/find_input_delta_proto/file_list.proto";
+
+// These field numbers are also found in the inner message declarations.
+// We verify that the values are the same, and that every enum value is checked
+// in combined_metrics_test.go.
+// Do not change this enum without also updating:
+//  - the submessage's .proto file
+//  - combined_metrics_test.go
+enum FieldNumbers {
+  FIELD_NUMBERS_UNSPECIFIED = 0;
+  FIELD_NUMBERS_FILE_LIST = 1;
+}
+
+message SoongCombinedMetrics {
+  // cmd/find_input_delta/find_input_delta_proto.FileList
+  optional android.find_input_delta_proto.FileList file_list = 1;
+}
diff --git a/ui/metrics/metrics_proto/combined_metrics_test.go b/ui/metrics/metrics_proto/combined_metrics_test.go
new file mode 100644
index 0000000..eedb12a
--- /dev/null
+++ b/ui/metrics/metrics_proto/combined_metrics_test.go
@@ -0,0 +1,33 @@
+package metrics_proto
+
+import (
+	"testing"
+
+	find_input_delta_proto "android/soong/cmd/find_input_delta/find_input_delta_proto"
+)
+
+func TestCombinedMetricsMessageNums(t *testing.T) {
+	testCases := []struct {
+		Name         string
+		FieldNumbers map[string]int32
+	}{
+		{
+			Name:         "find_input_delta_proto",
+			FieldNumbers: find_input_delta_proto.FieldNumbers_value,
+		},
+	}
+	verifiedMap := make(map[string]bool)
+	for _, tc := range testCases {
+		for k, v := range tc.FieldNumbers {
+			if FieldNumbers_value[k] != v {
+				t.Errorf("%s: Expected FieldNumbers.%s == %v, found %v", tc.Name, k, FieldNumbers_value[k], v)
+			}
+			verifiedMap[k] = true
+		}
+	}
+	for k, v := range FieldNumbers_value {
+		if !verifiedMap[k] {
+			t.Errorf("No test case verifies FieldNumbers.%s=%v", k, v)
+		}
+	}
+}
diff --git a/ui/metrics/metrics_proto/regen.sh b/ui/metrics/metrics_proto/regen.sh
index 8eb2d74..5e5f9b8 100755
--- a/ui/metrics/metrics_proto/regen.sh
+++ b/ui/metrics/metrics_proto/regen.sh
@@ -12,6 +12,6 @@
   die "could not find aprotoc. ${error_msg}"
 fi
 
-if ! aprotoc --go_out=paths=source_relative:. metrics.proto; then
+if ! aprotoc --go_out=paths=source_relative:. -I .:../../.. metrics.proto combined_metrics.proto; then
   die "build failed. ${error_msg}"
 fi