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https://issues.apache.org/jira/browse/BEAM-3612?focusedWorklogId=164597&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-164597
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ASF GitHub Bot logged work on BEAM-3612:
----------------------------------------
Author: ASF GitHub Bot
Created on: 10/Nov/18 01:10
Start Date: 10/Nov/18 01:10
Worklog Time Spent: 10m
Work Description: lostluck commented on a change in pull request #7000:
[BEAM-3612] Add a shim generator tool
URL: https://github.com/apache/beam/pull/7000#discussion_r232434065
##########
File path: sdks/go/pkg/beam/util/starcgenx/starcgenx.go
##########
@@ -0,0 +1,565 @@
+// 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 starcgenx is a Static Analysis Type Assertion shim and Registration
Code Generator
+// which provides an extractor to extract types from a package, in order to
generate
+// approprate shimsr a package so code can be generated for it.
+//
+// It's written for use by the starcgen tool, but separate to permit
+// alternative "go/importer" Importers for accessing types from imported
packages.
+package starcgenx
+
+import (
+ "bytes"
+ "fmt"
+ "go/ast"
+ "go/token"
+ "go/types"
+ "strings"
+
+ "github.com/apache/beam/sdks/go/pkg/beam/util/shimx"
+)
+
+// NewExtractor returns an extractor for the given package.
+func NewExtractor(pkg string) *Extractor {
+ return &Extractor{
+ Package: pkg,
+ functions: make(map[string]struct{}),
+ types: make(map[string]struct{}),
+ funcs: make(map[string]*types.Signature),
+ emits: make(map[string]shimx.Emitter),
+ iters: make(map[string]shimx.Input),
+ imports: make(map[string]struct{}),
+ allExported: true,
+ }
+}
+
+// Extractor contains and uniquifies the cache of types and things that need
to be generated.
+type Extractor struct {
+ w bytes.Buffer
+ Package string
+ debug bool
+
+ // Ids is an optional slice of package local identifiers
+ Ids []string
+
+ // Register and uniquify the needed shims for each kind.
+ // Functions to Register
+ functions map[string]struct{}
+ // Types to Register (structs, essentially)
+ types map[string]struct{}
+ // FuncShims needed
+ funcs map[string]*types.Signature
+ // Emitter Shims needed
+ emits map[string]shimx.Emitter
+ // Iterator Shims needed
+ iters map[string]shimx.Input
+
+ // list of packages we need to import.
+ imports map[string]struct{}
+
+ allExported bool // Marks if all ptransforms are exported and available
in main.
+}
+
+// Summary prints out a summary of the shims and registrations to
+// be generated to the buffer.
+func (e *Extractor) Summary() {
+ e.Print("\n")
+ e.Print("Summary\n")
+ e.Printf("All exported?: %v\n", e.allExported)
+ e.Printf("%d\t Functions\n", len(e.functions))
+ e.Printf("%d\t Types\n", len(e.types))
+ e.Printf("%d\t Shims\n", len(e.funcs))
+ e.Printf("%d\t Emits\n", len(e.emits))
+ e.Printf("%d\t Inputs\n", len(e.iters))
+}
+
+// lifecycleMethodName returns if the passed in string is one of the lifecycle
method names used
+// by the Go SDK as DoFn or CombineFn lifecycle methods. These are the only
methods that need
+// shims generated for them, as per beam/core/graph/fn.go
+// TODO(lostluck): Move this to beam/core/graph/fn.go, so it can stay up to
date.
+func lifecycleMethodName(n string) bool {
+ switch n {
+ case "ProcessElement", "StartBundle", "FinishBundle", "Setup",
"Teardown", "CreateAccumulator", "AddInput", "MergeAccumulators",
"ExtractOutput", "Compact":
+ return true
+ default:
+ return false
+ }
+}
+
+// Bytes forwards to fmt.Fprint to the extractor buffer.
+func (e *Extractor) Bytes() []byte {
+ return e.w.Bytes()
+}
+
+// Print forwards to fmt.Fprint to the extractor buffer.
+func (e *Extractor) Print(s string) {
+ if e.debug {
+ fmt.Fprint(&e.w, s)
+ }
+}
+
+// Printf forwards to fmt.Printf to the extractor buffer.
+func (e *Extractor) Printf(f string, args ...interface{}) {
+ if e.debug {
+ fmt.Fprintf(&e.w, f, args...)
+ }
+}
+
+// FromAsts analyses the contents of a package
+func (e *Extractor) FromAsts(imp types.Importer, fset *token.FileSet, files
[]*ast.File) error {
+ conf := types.Config{
+ Importer: imp,
+ IgnoreFuncBodies: true,
+ DisableUnusedImportCheck: true,
+ }
+ info := &types.Info{
+ Defs: make(map[*ast.Ident]types.Object),
+ }
+ if len(e.Ids) != 0 {
+ // TODO(lostluck): This becomes unnnecessary iff we can figure
out
+ // which ParDos are being passed to beam.ParDo or beam.Combine.
+ // If there are ids, we need to also look at function bodies,
and uses.
+ var checkFuncBodies bool
+ for _, v := range e.Ids {
+ if strings.Contains(v, ".") {
+ checkFuncBodies = true
+ break
+ }
+ }
+ conf.IgnoreFuncBodies = !checkFuncBodies
+ info.Uses = make(map[*ast.Ident]types.Object)
+ }
+
+ if _, err := conf.Check(e.Package, fset, files, info); err != nil {
+ return fmt.Errorf("failed to type check package %s : %v",
e.Package, err)
+ }
+
+ e.Print("/*\n")
+ var idsRequired, idsFound map[string]bool
+ if len(e.Ids) > 0 {
+ e.Printf("Filtering by %d identifiers: %q\n", len(e.Ids),
strings.Join(e.Ids, ", "))
+ idsRequired = make(map[string]bool)
+ idsFound = make(map[string]bool)
+ for _, id := range e.Ids {
+ idsRequired[id] = true
+ }
+ }
+ // TODO(rebo): Need to sort out struct types and their methods, so we
only
+ // register structs that are used as function parameters, or that are
clearly
+ // DoFns or CombineFns.
+ e.Print("CHECKING DEFS\n")
+ for id, obj := range info.Defs {
+ e.fromObj(fset, id, obj, idsRequired, idsFound)
+ }
+ e.Print("CHECKING USES\n")
+ for id, obj := range info.Uses {
+ e.fromObj(fset, id, obj, idsRequired, idsFound)
+ }
+ var notFound []string
+ for _, k := range e.Ids {
+ if !idsFound[k] {
+ notFound = append(notFound, k)
+ }
+ }
+ if len(notFound) > 0 {
+ return fmt.Errorf("couldn't find the following identifiers;
please check for typos, or remove them: %v", strings.Join(notFound, ", "))
+ }
+ e.Print("*/\n")
+
+ return nil
+}
+
+func (e *Extractor) isRequired(ident string, obj types.Object, idsRequired,
idsFound map[string]bool) bool {
+ if idsRequired == nil {
+ return true
+ }
+ if idsFound == nil {
+ panic("broken invariant: idsFound map is nil, but idsRequired
map exists")
+ }
+ // If we're filtering IDs, then it needs to be in the filtered
identifiers,
+ // or it's receiver type identifier needs to be in the filtered
identifiers.
+ if idsRequired[ident] {
+ idsFound[ident] = true
+ return true
+ }
+ // Check if this is a function.
+ sig, ok := obj.Type().(*types.Signature)
+ if !ok {
+ return false
+ }
+ // If this is a function, and it has a receiver, it's a method.
+ if recv := sig.Recv(); recv != nil && lifecycleMethodName(ident) {
+ // We don't want to care about pointers, so dereference to
value type.
+ t := recv.Type()
+ p, ok := t.(*types.Pointer)
+ for ok {
+ t = p.Elem()
+ p, ok = t.(*types.Pointer)
+ }
+ ts := types.TypeString(t, e.qualifier)
+ e.Printf("RRR has %v, ts: %s %s--- ", sig, ts, ident)
+ if !idsRequired[ts] {
+ e.Print("IGNORE\n")
+ return false
+ }
+ e.Print("KEEP\n")
+ idsFound[ts] = true
+ return true
+ }
+ return false
+}
+
+func (e *Extractor) fromObj(fset *token.FileSet, id *ast.Ident, obj
types.Object, idsRequired, idsFound map[string]bool) {
+ if obj == nil { // Omit the package declaration.
+ e.Printf("%s: %q has no object, probably a package\n",
+ fset.Position(id.Pos()), id.Name)
+ return
+ }
+
+ pkg := obj.Pkg()
+ if pkg == nil {
+ e.Printf("%s: %q has no package \n",
+ fset.Position(id.Pos()), id.Name)
+ // No meaningful identifier.
+ return
+ }
+ ident := fmt.Sprintf("%s.%s", pkg.Name(), obj.Name())
+ if pkg.Name() == e.Package {
+ ident = obj.Name()
+ }
+ if !e.isRequired(ident, obj, idsRequired, idsFound) {
+ return
+ }
+
+ switch ot := obj.(type) {
+ case *types.Var:
+ // Vars are tricky since they could be anything, and anywhere
(package scope, parameters, etc)
+ // eg. Flags, or Field Tags, among others.
+ // I'm increasingly convinced that we should simply igonore
vars.
+ // Do nothing for vars.
+ case *types.Func:
+ sig := obj.Type().(*types.Signature)
+ if recv := sig.Recv(); recv != nil {
+ // Methods don't need registering, but they do need
shim generation.
+ e.Printf("%s: %q is a method of %v -> %v--- %T %v %v
%v\n",
+ fset.Position(id.Pos()), id.Name, recv.Type(),
obj, obj, id, obj.Pkg(), obj.Type())
+ if !lifecycleMethodName(id.Name) {
+ // If this is not a lifecycle method, we should
ignore it.
+ return
+ }
+ } else if id.Name != "init" {
+ // init functions are special and should be ignored.
+ // Functions need registering, as well as shim
generation.
+ e.Printf("%s: %q is a top level func %v --- %T %v %v
%v\n",
+ fset.Position(id.Pos()), ident, obj, obj, id,
obj.Pkg(), obj.Type())
+ e.functions[ident] = struct{}{}
+ }
+ // For functions from other packages.
+ if pkg.Name() != e.Package {
+ e.imports[pkg.Path()] = struct{}{}
+ }
+
+ e.funcs[e.sigKey(sig)] = sig
+ e.extractParameters(sig)
+ e.Printf("\t%v\n", sig)
+ case *types.TypeName:
+ e.Printf("%s: %q is a type %v --- %T %v %v %v %v\n",
+ fset.Position(id.Pos()), id.Name, obj, obj, id,
obj.Pkg(), obj.Type(), obj.Name())
+ // Probably need to sanity check that this type actually is/has
a ProcessElement
+ // or MergeAccumulators defined for this type so unnecessary
registrations don't happen,
+ // an can explicitly produce an error if an explicitly named
type *isn't* a DoFn or CombineFn.
+ e.extractType(ot)
+ default:
+ e.Printf("%s: %q defines %v --- %T %v %v %v\n",
+ fset.Position(id.Pos()), types.ObjectString(obj,
e.qualifier), obj, obj, id, obj.Pkg(), obj.Type())
+ }
+}
+
+func (e *Extractor) extractType(ot *types.TypeName) {
+ name := types.TypeString(ot.Type(), e.qualifier)
+ // Unwrap an alias by one level.
+ // Attempting to deference a full chain of aliases runs the risk of
crossing
+ // a visibility boundary such as internal packages.
+ // A single level is safe since the code we're analysing imports it,
+ // so we can assume the generated code can access it too.
+ if ot.IsAlias() {
+ if t, ok := ot.Type().(*types.Named); ok {
+ ot = t.Obj()
+ name = types.TypeString(t, e.qualifier)
+
+ if pkg := t.Obj().Pkg(); pkg != nil {
+ e.imports[pkg.Path()] = struct{}{}
+ }
+ }
+ }
+ e.types[name] = struct{}{}
+}
+
+// Examines the signature and extracts types of parameters for generating
+// necessary imports and emitter and iterator code.
+func (e *Extractor) extractParameters(sig *types.Signature) {
+ in := sig.Params() // *types.Tuple
+ for i := 0; i < in.Len(); i++ {
+ s := in.At(i) // *types.Var
+
+ // Pointer types need to be iteratively unwrapped until we're
at the base type,
+ // so we can get the import if necessary.
+ t := s.Type()
+ p, ok := t.(*types.Pointer)
+ for ok {
+ t = p.Elem()
+ p, ok = t.(*types.Pointer)
+ }
+ // Here's were we ensure we register new imports.
+ if t, ok := t.(*types.Named); ok {
+ if pkg := t.Obj().Pkg(); pkg != nil {
+ e.imports[pkg.Path()] = struct{}{}
Review comment:
1. Exactly, empty struct, being initialized.
2. an empty struct has size 0, so this makes maps functionally a set, with
only the map bits.
This is useful for de-duplicating entries by key.
The alternative is to use booleans, which is more concise when subsequently
checking presence
eg.
foo := make(map[string]bool)
if foo["bar] {
Baz()
}
vs
foo := make(map[string]struct{})
if _, ok := foo["bar"]; ok {
Baz()
}
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Issue Time Tracking
-------------------
Worklog Id: (was: 164597)
Time Spent: 5h (was: 4h 50m)
> Make it easy to generate type-specialized Go SDK reflectx.Funcs
> ---------------------------------------------------------------
>
> Key: BEAM-3612
> URL: https://issues.apache.org/jira/browse/BEAM-3612
> Project: Beam
> Issue Type: Improvement
> Components: sdk-go
> Reporter: Henning Rohde
> Assignee: Robert Burke
> Priority: Major
> Time Spent: 5h
> Remaining Estimate: 0h
>
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