[
https://issues.apache.org/jira/browse/BEAM-3910?focusedWorklogId=87649&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-87649
]
ASF GitHub Bot logged work on BEAM-3910:
----------------------------------------
Author: ASF GitHub Bot
Created on: 04/Apr/18 17:21
Start Date: 04/Apr/18 17:21
Worklog Time Spent: 10m
Work Description: wcn3 commented on a change in pull request #4941:
BEAM-3910: Add float support for the Go SDK.
URL: https://github.com/apache/beam/pull/4941#discussion_r179219605
##########
File path: sdks/go/pkg/beam/core/runtime/coderx/float.go
##########
@@ -0,0 +1,75 @@
+// Licensed to the Apache Software Foundation (ASF) under one or more
+// contributor license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright ownership.
+// The ASF licenses this file to You 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 coderx
+
+import (
+ "fmt"
+ "math"
+ "math/bits"
+ "reflect"
+
+ "github.com/apache/beam/sdks/go/pkg/beam/core/graph/coder"
+ "github.com/apache/beam/sdks/go/pkg/beam/core/runtime"
+ "github.com/apache/beam/sdks/go/pkg/beam/core/typex"
+ "github.com/apache/beam/sdks/go/pkg/beam/core/util/reflectx"
+)
+
+func init() {
+ runtime.RegisterFunction(encFloat)
+ runtime.RegisterFunction(decFloat)
+}
+
+func encFloat(v typex.T) []byte {
+ var val float64
+ switch n := v.(type) {
+ case float32:
+ val = float64(n)
+ case float64:
+ val = n
+ default:
+ panic(fmt.Sprintf("received unknown value type: want a float,
got %T", n))
+ }
+
+ return encVarUintZ(bits.ReverseBytes64(math.Float64bits(val)))
+}
+
+func decFloat(t reflect.Type, data []byte) (typex.T, error) {
+ uval, err := decVarUintZ(reflectx.Uint64, data)
+ if err != nil {
+ return nil, fmt.Errorf("invalid float encoding for: %v", data)
+ }
+
+ n := math.Float64frombits(bits.ReverseBytes64(uval.(uint64)))
+ switch t.Kind() {
+ case reflect.Float64:
+ return n, nil
+ case reflect.Float32:
+ return float32(n), nil
+ default:
+ panic(fmt.Sprintf("unreachable statement: expected a float, got
%v", t))
+ }
+}
+
+// NewFloat returns a coder for the given float type. It uses the same
+// encoding scheme as the gob package.
+func NewFloat(t reflect.Type) (*coder.CustomCoder, error) {
Review comment:
If it's faster, I'd like to do it for integer types as well since those are
more prevalent. I'm happy to explore that as future work, but for now, I'd like
to leave it like this.
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Issue Time Tracking
-------------------
Worklog Id: (was: 87649)
Time Spent: 50m (was: 40m)
Remaining Estimate: 23h 10m (was: 23h 20m)
> Support floating point values in Go SDK
> ---------------------------------------
>
> Key: BEAM-3910
> URL: https://issues.apache.org/jira/browse/BEAM-3910
> Project: Beam
> Issue Type: New Feature
> Components: sdk-go
> Reporter: Bill Neubauer
> Assignee: Bill Neubauer
> Priority: Major
> Original Estimate: 24h
> Time Spent: 50m
> Remaining Estimate: 23h 10m
>
> The Go SDK supports all the integer types of the language, but does not
> support floats.
> My plan for coding is to use the same technique the gob package uses, which
> results in a compact encoding for simple values.
> [https://golang.org/src/encoding/gob/encode.go?#L210|https://golang.org/src/encoding/gob/encode.go#L210]
> with rationale explained in
> https://golang.org/pkg/encoding/gob/#hdr-Encoding_Details
> The resulting uint is then encoded using the existing coders in coderx.
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