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feat(bigquery/storage/managedwriter/adapt): add schema -> proto suppo…
…rt (#4375) * feat(bigquery managedstorage): add schema -> proto support
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// Copyright 2021 Google LLC | ||
// | ||
// 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 | ||
// | ||
// https://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. | ||
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package adapt | ||
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import "fmt" | ||
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type conversionError struct { | ||
Location string | ||
Details error | ||
} | ||
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func (ce *conversionError) Error() string { | ||
if ce.Location == "" { | ||
return ce.Details.Error() | ||
} | ||
return fmt.Sprintf("conversion error in location %q: %v", ce.Location, ce.Details) | ||
} | ||
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func newConversionError(loc string, err error) *conversionError { | ||
return &conversionError{ | ||
Location: loc, | ||
Details: err, | ||
} | ||
} |
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bigquery/storage/managedwriter/adapt/protoconversion.go
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// Copyright 2021 Google LLC | ||
// | ||
// 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 | ||
// | ||
// https://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. | ||
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package adapt | ||
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import ( | ||
"encoding/base64" | ||
"fmt" | ||
"strings" | ||
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storagepb "google.golang.org/genproto/googleapis/cloud/bigquery/storage/v1beta2" | ||
"google.golang.org/protobuf/proto" | ||
"google.golang.org/protobuf/reflect/protodesc" | ||
"google.golang.org/protobuf/reflect/protoreflect" | ||
"google.golang.org/protobuf/types/descriptorpb" | ||
"google.golang.org/protobuf/types/known/wrapperspb" | ||
) | ||
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// bqModeToFieldLabelMap holds mapping from field schema mode to proto label. | ||
// proto3 no longer allows use of REQUIRED labels, so we solve that elsewhere | ||
// and simply use optional. | ||
var bqModeToFieldLabelMap = map[storagepb.TableFieldSchema_Mode]descriptorpb.FieldDescriptorProto_Label{ | ||
storagepb.TableFieldSchema_NULLABLE: descriptorpb.FieldDescriptorProto_LABEL_OPTIONAL, | ||
storagepb.TableFieldSchema_REPEATED: descriptorpb.FieldDescriptorProto_LABEL_REPEATED, | ||
storagepb.TableFieldSchema_REQUIRED: descriptorpb.FieldDescriptorProto_LABEL_OPTIONAL, | ||
} | ||
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// Allows conversion between BQ schema type and FieldDescriptorProto's type. | ||
var bqTypeToFieldTypeMap = map[storagepb.TableFieldSchema_Type]descriptorpb.FieldDescriptorProto_Type{ | ||
storagepb.TableFieldSchema_BIGNUMERIC: descriptorpb.FieldDescriptorProto_TYPE_BYTES, | ||
storagepb.TableFieldSchema_BOOL: descriptorpb.FieldDescriptorProto_TYPE_BOOL, | ||
storagepb.TableFieldSchema_BYTES: descriptorpb.FieldDescriptorProto_TYPE_BYTES, | ||
storagepb.TableFieldSchema_DATE: descriptorpb.FieldDescriptorProto_TYPE_INT32, | ||
storagepb.TableFieldSchema_DATETIME: descriptorpb.FieldDescriptorProto_TYPE_INT64, | ||
storagepb.TableFieldSchema_DOUBLE: descriptorpb.FieldDescriptorProto_TYPE_DOUBLE, | ||
storagepb.TableFieldSchema_GEOGRAPHY: descriptorpb.FieldDescriptorProto_TYPE_STRING, | ||
storagepb.TableFieldSchema_INT64: descriptorpb.FieldDescriptorProto_TYPE_INT64, | ||
storagepb.TableFieldSchema_NUMERIC: descriptorpb.FieldDescriptorProto_TYPE_BYTES, | ||
storagepb.TableFieldSchema_STRING: descriptorpb.FieldDescriptorProto_TYPE_STRING, | ||
storagepb.TableFieldSchema_STRUCT: descriptorpb.FieldDescriptorProto_TYPE_MESSAGE, | ||
storagepb.TableFieldSchema_TIME: descriptorpb.FieldDescriptorProto_TYPE_INT64, | ||
storagepb.TableFieldSchema_TIMESTAMP: descriptorpb.FieldDescriptorProto_TYPE_INT64, | ||
} | ||
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// For TableFieldSchema OPTIONAL mode, we use the wrapper types to allow for the | ||
// proper representation of NULL values, as proto3 semantics would just use default value. | ||
var bqTypeToWrapperMap = map[storagepb.TableFieldSchema_Type]string{ | ||
storagepb.TableFieldSchema_BIGNUMERIC: ".google.protobuf.BytesValue", | ||
storagepb.TableFieldSchema_BOOL: ".google.protobuf.BoolValue", | ||
storagepb.TableFieldSchema_BYTES: ".google.protobuf.BytesValue", | ||
storagepb.TableFieldSchema_DATE: ".google.protobuf.Int32Value", | ||
storagepb.TableFieldSchema_DATETIME: ".google.protobuf.Int64Value", | ||
storagepb.TableFieldSchema_DOUBLE: ".google.protobuf.DoubleValue", | ||
storagepb.TableFieldSchema_GEOGRAPHY: ".google.protobuf.StringValue", | ||
storagepb.TableFieldSchema_INT64: ".google.protobuf.Int64Value", | ||
storagepb.TableFieldSchema_NUMERIC: ".google.protobuf.BytesValue", | ||
storagepb.TableFieldSchema_STRING: ".google.protobuf.StringValue", | ||
storagepb.TableFieldSchema_TIME: ".google.protobuf.Int64Value", | ||
storagepb.TableFieldSchema_TIMESTAMP: ".google.protobuf.Int64Value", | ||
} | ||
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// filename used by well known types proto | ||
var wellKnownTypesWrapperName = "google/protobuf/wrappers.proto" | ||
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// dependencyCache is used to reduce the number of unique messages we generate by caching based on the tableschema. | ||
// | ||
// keys are based on the base64-encoded serialized tableschema value. | ||
type dependencyCache map[string]protoreflect.Descriptor | ||
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func (dm dependencyCache) get(schema *storagepb.TableSchema) protoreflect.Descriptor { | ||
if dm == nil { | ||
return nil | ||
} | ||
b, err := proto.Marshal(schema) | ||
if err != nil { | ||
return nil | ||
} | ||
encoded := base64.StdEncoding.EncodeToString(b) | ||
if desc, ok := (dm)[encoded]; ok { | ||
return desc | ||
} | ||
return nil | ||
} | ||
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func (dm dependencyCache) add(schema *storagepb.TableSchema, descriptor protoreflect.Descriptor) error { | ||
if dm == nil { | ||
return fmt.Errorf("cache is nil") | ||
} | ||
b, err := proto.Marshal(schema) | ||
if err != nil { | ||
return fmt.Errorf("failed to serialize tableschema: %v", err) | ||
} | ||
encoded := base64.StdEncoding.EncodeToString(b) | ||
(dm)[encoded] = descriptor | ||
return nil | ||
} | ||
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// StorageSchemaToDescriptor builds a protoreflect.Descriptor for a given table schema. | ||
func StorageSchemaToDescriptor(inSchema *storagepb.TableSchema, scope string) (protoreflect.Descriptor, error) { | ||
dc := make(dependencyCache) | ||
// TODO: b/193064992 tracks support for wrapper types. In the interim, disable wrapper usage. | ||
return storageSchemaToDescriptorInternal(inSchema, scope, &dc, false) | ||
} | ||
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// internal implementation of the conversion code. | ||
func storageSchemaToDescriptorInternal(inSchema *storagepb.TableSchema, scope string, cache *dependencyCache, allowWrapperTypes bool) (protoreflect.Descriptor, error) { | ||
if inSchema == nil { | ||
return nil, newConversionError(scope, fmt.Errorf("no input schema was provided")) | ||
} | ||
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var fields []*descriptorpb.FieldDescriptorProto | ||
var deps []protoreflect.FileDescriptor | ||
var fNumber int32 | ||
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for _, f := range inSchema.GetFields() { | ||
fNumber = fNumber + 1 | ||
currentScope := fmt.Sprintf("%s__%s", scope, f.GetName()) | ||
// If we're dealing with a STRUCT type, we must deal with sub messages. | ||
// As multiple submessages may share the same type definition, we use a dependency cache | ||
// and interrogate it / populate it as we're going. | ||
if f.Type == storagepb.TableFieldSchema_STRUCT { | ||
foundDesc := cache.get(&storagepb.TableSchema{Fields: f.GetFields()}) | ||
if foundDesc != nil { | ||
// check to see if we already have this in current dependency list | ||
haveDep := false | ||
for _, curDep := range deps { | ||
if foundDesc.ParentFile().FullName() == curDep.FullName() { | ||
haveDep = true | ||
break | ||
} | ||
} | ||
// if dep is missing, add to current dependencies | ||
if !haveDep { | ||
deps = append(deps, foundDesc.ParentFile()) | ||
} | ||
// construct field descriptor for the message | ||
fdp, err := tableFieldSchemaToFieldDescriptorProto(f, fNumber, string(foundDesc.FullName()), allowWrapperTypes) | ||
if err != nil { | ||
return nil, newConversionError(scope, fmt.Errorf("couldn't convert field to FieldDescriptorProto: %v", err)) | ||
} | ||
fields = append(fields, fdp) | ||
} else { | ||
// Wrap the current struct's fields in a TableSchema outer message, and then build the submessage. | ||
ts := &storagepb.TableSchema{ | ||
Fields: f.GetFields(), | ||
} | ||
desc, err := storageSchemaToDescriptorInternal(ts, currentScope, cache, allowWrapperTypes) | ||
if err != nil { | ||
return nil, newConversionError(currentScope, fmt.Errorf("couldn't convert message: %v", err)) | ||
} | ||
// Now that we have the submessage definition, we append it both to the local dependencies, as well | ||
// as inserting it into the cache for possible reuse elsewhere. | ||
deps = append(deps, desc.ParentFile()) | ||
err = cache.add(ts, desc) | ||
if err != nil { | ||
return nil, newConversionError(currentScope, fmt.Errorf("failed to add descriptor to dependency cache: %v", err)) | ||
} | ||
fdp, err := tableFieldSchemaToFieldDescriptorProto(f, fNumber, currentScope, allowWrapperTypes) | ||
if err != nil { | ||
return nil, newConversionError(currentScope, fmt.Errorf("couldn't compute field schema : %v", err)) | ||
} | ||
fields = append(fields, fdp) | ||
} | ||
} else { | ||
fd, err := tableFieldSchemaToFieldDescriptorProto(f, fNumber, currentScope, allowWrapperTypes) | ||
if err != nil { | ||
return nil, newConversionError(currentScope, err) | ||
} | ||
fields = append(fields, fd) | ||
} | ||
} | ||
// Start constructing a DescriptorProto. | ||
dp := &descriptorpb.DescriptorProto{ | ||
Name: proto.String(scope), | ||
Field: fields, | ||
} | ||
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// Use the local dependencies to generate a list of filenames. | ||
depNames := []string{ | ||
wellKnownTypesWrapperName, | ||
} | ||
for _, d := range deps { | ||
depNames = append(depNames, d.ParentFile().Path()) | ||
} | ||
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// Now, construct a FileDescriptorProto. | ||
fdp := &descriptorpb.FileDescriptorProto{ | ||
MessageType: []*descriptorpb.DescriptorProto{dp}, | ||
Name: proto.String(fmt.Sprintf("%s.proto", scope)), | ||
Syntax: proto.String("proto3"), | ||
Dependency: depNames, | ||
} | ||
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// We'll need a FileDescriptorSet as we have a FileDescriptorProto for the current | ||
// descriptor we're building, but we need to include all the referenced dependencies. | ||
fds := &descriptorpb.FileDescriptorSet{ | ||
File: []*descriptorpb.FileDescriptorProto{ | ||
fdp, | ||
protodesc.ToFileDescriptorProto(wrapperspb.File_google_protobuf_wrappers_proto), | ||
}, | ||
} | ||
for _, d := range deps { | ||
fds.File = append(fds.File, protodesc.ToFileDescriptorProto(d)) | ||
} | ||
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// Load the set into a registry, then interrogate it for the descriptor corresponding to the top level message. | ||
files, err := protodesc.NewFiles(fds) | ||
if err != nil { | ||
return nil, err | ||
} | ||
return files.FindDescriptorByName(protoreflect.FullName(scope)) | ||
} | ||
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// tableFieldSchemaToFieldDescriptorProto builds individual field descriptors for a proto message. | ||
// We're using proto3 syntax, but BigQuery supports the notion of NULLs which conflicts with proto3 default value | ||
// behavior. To enable it, we look for nullable fields in the schema that should be scalars, and use the | ||
// well-known wrapper types. | ||
// | ||
// Messages are always nullable, and repeated fields are as well. | ||
func tableFieldSchemaToFieldDescriptorProto(field *storagepb.TableFieldSchema, idx int32, scope string, allowWrapperTypes bool) (*descriptorpb.FieldDescriptorProto, error) { | ||
name := strings.ToLower(field.GetName()) | ||
if field.GetType() == storagepb.TableFieldSchema_STRUCT { | ||
return &descriptorpb.FieldDescriptorProto{ | ||
Name: proto.String(name), | ||
Number: proto.Int32(idx), | ||
TypeName: proto.String(scope), | ||
Label: bqModeToFieldLabelMap[field.GetMode()].Enum(), | ||
}, nil | ||
} | ||
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// For (REQUIRED||REPEATED) fields, we use the expected scalar types, but the proto is | ||
// still marked OPTIONAL (proto3 semantics). | ||
if field.GetMode() != storagepb.TableFieldSchema_NULLABLE || !allowWrapperTypes { | ||
return &descriptorpb.FieldDescriptorProto{ | ||
Name: proto.String(name), | ||
Number: proto.Int32(idx), | ||
Type: bqTypeToFieldTypeMap[field.GetType()].Enum(), | ||
Label: bqModeToFieldLabelMap[field.GetMode()].Enum(), | ||
}, nil | ||
} | ||
// For NULLABLE, optionally use wrapper types. | ||
return &descriptorpb.FieldDescriptorProto{ | ||
Name: proto.String(name), | ||
Number: proto.Int32(idx), | ||
Type: descriptorpb.FieldDescriptorProto_TYPE_MESSAGE.Enum(), | ||
TypeName: proto.String(bqTypeToWrapperMap[field.GetType()]), | ||
Label: descriptorpb.FieldDescriptorProto_LABEL_OPTIONAL.Enum(), | ||
}, nil | ||
} |
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