[
https://issues.apache.org/jira/browse/BEAM-3910?focusedWorklogId=83389&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-83389
]
ASF GitHub Bot logged work on BEAM-3910:
----------------------------------------
Author: ASF GitHub Bot
Created on: 22/Mar/18 23:55
Start Date: 22/Mar/18 23:55
Worklog Time Spent: 10m
Work Description: herohde 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_r176606245
##########
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:
Given there are only 2 types, perhaps do them separately to avoid the
reflect.Type everywhere? I.e.,
NewFloat32
NewFloat64
encFloat32
etc
Presumably faster, too, but not sure if it matters.
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Issue Time Tracking
-------------------
Worklog Id: (was: 83389)
Time Spent: 0.5h (was: 20m)
Remaining Estimate: 23.5h (was: 23h 40m)
> 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: 0.5h
> Remaining Estimate: 23.5h
>
> 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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