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op.go
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op.go
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package kernel
import (
"context"
"errors"
"fmt"
"slices"
"strings"
"sync"
"github.com/brimdata/zed"
"github.com/brimdata/zed/compiler/ast"
"github.com/brimdata/zed/compiler/ast/dag"
"github.com/brimdata/zed/compiler/data"
"github.com/brimdata/zed/compiler/optimizer/demand"
"github.com/brimdata/zed/lake"
"github.com/brimdata/zed/order"
"github.com/brimdata/zed/pkg/field"
"github.com/brimdata/zed/runtime/expr"
"github.com/brimdata/zed/runtime/op"
"github.com/brimdata/zed/runtime/op/combine"
"github.com/brimdata/zed/runtime/op/explode"
"github.com/brimdata/zed/runtime/op/exprswitch"
"github.com/brimdata/zed/runtime/op/fork"
"github.com/brimdata/zed/runtime/op/fuse"
"github.com/brimdata/zed/runtime/op/head"
"github.com/brimdata/zed/runtime/op/join"
"github.com/brimdata/zed/runtime/op/load"
"github.com/brimdata/zed/runtime/op/merge"
"github.com/brimdata/zed/runtime/op/meta"
"github.com/brimdata/zed/runtime/op/pass"
"github.com/brimdata/zed/runtime/op/shape"
"github.com/brimdata/zed/runtime/op/sort"
"github.com/brimdata/zed/runtime/op/switcher"
"github.com/brimdata/zed/runtime/op/tail"
"github.com/brimdata/zed/runtime/op/top"
"github.com/brimdata/zed/runtime/op/traverse"
"github.com/brimdata/zed/runtime/op/uniq"
"github.com/brimdata/zed/runtime/op/yield"
"github.com/brimdata/zed/zbuf"
"github.com/brimdata/zed/zio"
"github.com/brimdata/zed/zson"
"github.com/segmentio/ksuid"
)
var ErrJoinParents = errors.New("join requires two upstream parallel query paths")
type Builder struct {
octx *op.Context
mctx *zed.Context
source *data.Source
progress *zbuf.Progress
deletes *sync.Map
funcs map[string]expr.Function
}
func NewBuilder(octx *op.Context, source *data.Source) *Builder {
return &Builder{
octx: octx,
mctx: zed.NewContext(),
source: source,
progress: &zbuf.Progress{
BytesRead: 0,
BytesMatched: 0,
RecordsRead: 0,
RecordsMatched: 0,
},
funcs: make(map[string]expr.Function),
}
}
type Reader struct {
SortKey order.SortKey
Filter dag.Expr
Readers []zio.Reader
}
var _ dag.Op = (*Reader)(nil)
var _ ast.Source = (*Reader)(nil)
func (*Reader) OpNode() {}
func (*Reader) Source() {}
func (b *Builder) Build(seq dag.Seq) ([]zbuf.Puller, error) {
if !isEntry(seq) {
return nil, errors.New("internal error: DAG entry point is not a data source")
}
return b.compileSeq(seq, nil)
}
func (b *Builder) zctx() *zed.Context {
return b.octx.Zctx
}
func (b *Builder) Meter() zbuf.Meter {
return b.progress
}
func (b *Builder) Deletes() *sync.Map {
return b.deletes
}
func (b *Builder) compileLeaf(o dag.Op, parent zbuf.Puller) (zbuf.Puller, error) {
switch v := o.(type) {
case *dag.Summarize:
return b.compileGroupBy(parent, v)
case *dag.Cut:
assignments, err := b.compileAssignments(v.Args)
if err != nil {
return nil, err
}
lhs, rhs := splitAssignments(assignments)
cutter := expr.NewCutter(b.octx.Zctx, lhs, rhs)
if v.Quiet {
cutter.Quiet()
}
return op.NewApplier(b.octx, parent, cutter), nil
case *dag.Drop:
if len(v.Args) == 0 {
return nil, errors.New("drop: no fields given")
}
fields := make(field.List, 0, len(v.Args))
for _, e := range v.Args {
field, ok := e.(*dag.This)
if !ok {
return nil, errors.New("drop: arg not a field")
}
fields = append(fields, field.Path)
}
dropper := expr.NewDropper(b.octx.Zctx, fields)
return op.NewApplier(b.octx, parent, dropper), nil
case *dag.Sort:
fields, err := b.compileExprs(v.Args)
if err != nil {
return nil, err
}
sort, err := sort.New(b.octx, parent, fields, v.Order, v.NullsFirst)
if err != nil {
return nil, fmt.Errorf("compiling sort: %w", err)
}
return sort, nil
case *dag.Head:
limit := v.Count
if limit == 0 {
limit = 1
}
return head.New(parent, limit), nil
case *dag.Tail:
limit := v.Count
if limit == 0 {
limit = 1
}
return tail.New(parent, limit), nil
case *dag.Uniq:
return uniq.New(b.octx, parent, v.Cflag), nil
case *dag.Pass:
return pass.New(parent), nil
case *dag.Filter:
f, err := b.compileExpr(v.Expr)
if err != nil {
return nil, fmt.Errorf("compiling filter: %w", err)
}
return op.NewApplier(b.octx, parent, expr.NewFilterApplier(b.octx.Zctx, f)), nil
case *dag.Top:
fields, err := b.compileExprs(v.Args)
if err != nil {
return nil, fmt.Errorf("compiling top: %w", err)
}
return top.New(b.octx.Zctx, parent, v.Limit, fields, v.Flush), nil
case *dag.Put:
clauses, err := b.compileAssignments(v.Args)
if err != nil {
return nil, err
}
putter := expr.NewPutter(b.octx.Zctx, clauses)
return op.NewApplier(b.octx, parent, putter), nil
case *dag.Rename:
var srcs, dsts []*expr.Lval
for _, a := range v.Args {
src, err := b.compileLval(a.RHS)
if err != nil {
return nil, err
}
dst, err := b.compileLval(a.LHS)
if err != nil {
return nil, err
}
srcs = append(srcs, src)
dsts = append(dsts, dst)
}
renamer := expr.NewRenamer(b.octx.Zctx, srcs, dsts)
return op.NewApplier(b.octx, parent, renamer), nil
case *dag.Fuse:
return fuse.New(b.octx, parent)
case *dag.Shape:
return shape.New(b.octx, parent)
case *dag.Join:
return nil, ErrJoinParents
case *dag.Merge:
return nil, errors.New("merge: multiple upstream paths required")
case *dag.Explode:
typ, err := zson.ParseType(b.octx.Zctx, v.Type)
if err != nil {
return nil, err
}
args, err := b.compileExprs(v.Args)
if err != nil {
return nil, err
}
return explode.New(b.octx.Zctx, parent, args, typ, v.As)
case *dag.Over:
return b.compileOver(parent, v)
case *dag.Yield:
exprs, err := b.compileExprs(v.Exprs)
if err != nil {
return nil, err
}
t := yield.New(parent, exprs)
return t, nil
case *dag.PoolScan:
if parent != nil {
return nil, errors.New("internal error: pool scan cannot have a parent operator")
}
return b.compilePoolScan(v)
case *dag.PoolMetaScan:
return meta.NewPoolMetaScanner(b.octx.Context, b.octx.Zctx, b.source.Lake(), v.ID, v.Meta)
case *dag.CommitMetaScan:
var pruner expr.Evaluator
if v.Tap && v.KeyPruner != nil {
var err error
pruner, err = compileExpr(v.KeyPruner)
if err != nil {
return nil, err
}
}
return meta.NewCommitMetaScanner(b.octx.Context, b.octx.Zctx, b.source.Lake(), v.Pool, v.Commit, v.Meta, pruner)
case *dag.LakeMetaScan:
return meta.NewLakeMetaScanner(b.octx.Context, b.octx.Zctx, b.source.Lake(), v.Meta)
case *dag.HTTPScan:
body := strings.NewReader(v.Body)
return b.source.OpenHTTP(b.octx.Context, b.octx.Zctx, v.URL, v.Format, v.Method, v.Headers, body, demand.All())
case *dag.FileScan:
return b.source.Open(b.octx.Context, b.octx.Zctx, v.Path, v.Format, b.PushdownOf(v.Filter), demand.All())
case *Reader:
pushdown := b.PushdownOf(v.Filter)
if len(v.Readers) == 1 {
return zbuf.NewScanner(b.octx.Context, v.Readers[0], pushdown)
}
scanners := make([]zbuf.Scanner, 0, len(v.Readers))
for _, r := range v.Readers {
scanner, err := zbuf.NewScanner(b.octx.Context, r, pushdown)
if err != nil {
return nil, err
}
scanners = append(scanners, scanner)
}
return zbuf.MultiScanner(scanners...), nil
case *dag.Lister:
if parent != nil {
return nil, errors.New("internal error: data source cannot have a parent operator")
}
pool, err := b.lookupPool(v.Pool)
if err != nil {
return nil, err
}
var pruner expr.Evaluator
if v.KeyPruner != nil {
pruner, err = compileExpr(v.KeyPruner)
if err != nil {
return nil, err
}
}
return meta.NewSortedLister(b.octx.Context, b.mctx, b.source.Lake(), pool, v.Commit, pruner)
case *dag.Slicer:
return meta.NewSlicer(parent, b.mctx), nil
case *dag.SeqScan:
pool, err := b.lookupPool(v.Pool)
if err != nil {
return nil, err
}
var pruner expr.Evaluator
if v.KeyPruner != nil {
pruner, err = compileExpr(v.KeyPruner)
if err != nil {
return nil, err
}
}
return meta.NewSequenceScanner(b.octx, parent, pool, b.PushdownOf(v.Filter), pruner, b.progress), nil
case *dag.Deleter:
pool, err := b.lookupPool(v.Pool)
if err != nil {
return nil, err
}
var pruner expr.Evaluator
if v.KeyPruner != nil {
pruner, err = compileExpr(v.KeyPruner)
if err != nil {
return nil, err
}
}
if b.deletes == nil {
b.deletes = &sync.Map{}
}
var filter *DeleteFilter
if f := b.PushdownOf(v.Where); f != nil {
filter = &DeleteFilter{f}
}
return meta.NewDeleter(b.octx, parent, pool, filter, pruner, b.progress, b.deletes), nil
case *dag.Load:
return load.New(b.octx, b.source.Lake(), parent, v.Pool, v.Branch, v.Author, v.Message, v.Meta), nil
default:
return nil, fmt.Errorf("unknown DAG operator type: %v", v)
}
}
func (b *Builder) compileDefs(defs []dag.Def) ([]string, []expr.Evaluator, error) {
exprs := make([]expr.Evaluator, 0, len(defs))
names := make([]string, 0, len(defs))
for _, def := range defs {
e, err := b.compileExpr(def.Expr)
if err != nil {
return nil, nil, err
}
exprs = append(exprs, e)
names = append(names, def.Name)
}
return names, exprs, nil
}
func (b *Builder) compileOver(parent zbuf.Puller, over *dag.Over) (zbuf.Puller, error) {
if len(over.Defs) != 0 && over.Body == nil {
return nil, errors.New("internal error: over operator has defs but no body")
}
withNames, withExprs, err := b.compileDefs(over.Defs)
if err != nil {
return nil, err
}
exprs, err := b.compileExprs(over.Exprs)
if err != nil {
return nil, err
}
enter := traverse.NewOver(b.octx, parent, exprs)
if over.Body == nil {
return enter, nil
}
scope := enter.AddScope(b.octx.Context, withNames, withExprs)
exits, err := b.compileSeq(over.Body, []zbuf.Puller{scope})
if err != nil {
return nil, err
}
var exit zbuf.Puller
if len(exits) == 1 {
exit = exits[0]
} else {
// This can happen when output of over body
// is a fork or switch.
exit = combine.New(b.octx, exits)
}
return scope.NewExit(exit), nil
}
func (b *Builder) compileAssignments(assignments []dag.Assignment) ([]expr.Assignment, error) {
keys := make([]expr.Assignment, 0, len(assignments))
for _, assignment := range assignments {
a, err := b.compileAssignment(&assignment)
if err != nil {
return nil, err
}
keys = append(keys, a)
}
return keys, nil
}
func splitAssignments(assignments []expr.Assignment) ([]*expr.Lval, []expr.Evaluator) {
n := len(assignments)
lhs := make([]*expr.Lval, 0, n)
rhs := make([]expr.Evaluator, 0, n)
for _, a := range assignments {
lhs = append(lhs, a.LHS)
rhs = append(rhs, a.RHS)
}
return lhs, rhs
}
func (b *Builder) compileSeq(seq dag.Seq, parents []zbuf.Puller) ([]zbuf.Puller, error) {
for _, o := range seq {
var err error
parents, err = b.compile(o, parents)
if err != nil {
return nil, err
}
}
return parents, nil
}
func (b *Builder) compileScope(scope *dag.Scope, parents []zbuf.Puller) ([]zbuf.Puller, error) {
if err := b.compileFuncs(scope.Funcs); err != nil {
return nil, err
}
return b.compileSeq(scope.Body, parents)
}
func (b *Builder) compileFork(par *dag.Fork, parents []zbuf.Puller) ([]zbuf.Puller, error) {
var f *fork.Op
switch len(parents) {
case 0:
// No parents: no need for a fork since every op gets a nil parent.
case 1:
// Single parent: insert a fork for n-way fanout.
f = fork.New(b.octx, parents[0])
default:
// Multiple parents: insert a combine followed by a fork for n-way fanout.
f = fork.New(b.octx, combine.New(b.octx, parents))
}
var ops []zbuf.Puller
for _, seq := range par.Paths {
var parent zbuf.Puller
if f != nil && !isEntry(seq) {
parent = f.AddExit()
}
op, err := b.compileSeq(seq, []zbuf.Puller{parent})
if err != nil {
return nil, err
}
ops = append(ops, op...)
}
return ops, nil
}
func (b *Builder) compileScatter(par *dag.Scatter, parents []zbuf.Puller) ([]zbuf.Puller, error) {
if len(parents) != 1 {
return nil, errors.New("internal error: scatter operator requires a single parent")
}
var ops []zbuf.Puller
for _, o := range par.Paths {
op, err := b.compileSeq(o, parents[:1])
if err != nil {
return nil, err
}
ops = append(ops, op...)
}
return ops, nil
}
func (b *Builder) compileFuncs(fns []*dag.Func) error {
udfs := make([]*expr.UDF, 0, len(fns))
for _, f := range fns {
if _, ok := b.funcs[f.Name]; ok {
return fmt.Errorf("internal error: func %q declared twice", f.Name)
}
u := &expr.UDF{}
b.funcs[f.Name] = u
udfs = append(udfs, u)
}
for i := range fns {
var err error
if udfs[i].Body, err = b.compileExpr(fns[i].Expr); err != nil {
return err
}
}
return nil
}
func (b *Builder) compileExprSwitch(swtch *dag.Switch, parents []zbuf.Puller) ([]zbuf.Puller, error) {
if len(parents) != 1 {
return nil, errors.New("expression switch has multiple parents")
}
e, err := b.compileExpr(swtch.Expr)
if err != nil {
return nil, err
}
s := exprswitch.New(b.octx, parents[0], e)
var exits []zbuf.Puller
for _, c := range swtch.Cases {
var val *zed.Value
if c.Expr != nil {
val, err = b.evalAtCompileTime(c.Expr)
if err != nil {
return nil, err
}
if val.IsError() {
return nil, errors.New("switch case is not a constant expression")
}
}
parents, err := b.compileSeq(c.Path, []zbuf.Puller{s.AddCase(val)})
if err != nil {
return nil, err
}
exits = append(exits, parents...)
}
return exits, nil
}
func (b *Builder) compileSwitch(swtch *dag.Switch, parents []zbuf.Puller) ([]zbuf.Puller, error) {
n := len(swtch.Cases)
if len(parents) == 1 {
// Single parent: insert a switcher and wire to each branch.
switcher := switcher.New(b.octx, parents[0])
parents = []zbuf.Puller{}
for _, c := range swtch.Cases {
f, err := b.compileExpr(c.Expr)
if err != nil {
return nil, fmt.Errorf("compiling switch case filter: %w", err)
}
sc := switcher.AddCase(f)
parents = append(parents, sc)
}
}
if len(parents) != n {
return nil, fmt.Errorf("%d parents for switch with %d branches", len(parents), len(swtch.Cases))
}
var ops []zbuf.Puller
for k := 0; k < n; k++ {
o, err := b.compileSeq(swtch.Cases[k].Path, []zbuf.Puller{parents[k]})
if err != nil {
return nil, err
}
ops = append(ops, o...)
}
return ops, nil
}
// compile compiles a DAG into a graph of runtime operators, and returns
// the leaves.
func (b *Builder) compile(o dag.Op, parents []zbuf.Puller) ([]zbuf.Puller, error) {
switch o := o.(type) {
case *dag.Fork:
return b.compileFork(o, parents)
case *dag.Scatter:
return b.compileScatter(o, parents)
case *dag.Scope:
return b.compileScope(o, parents)
case *dag.Switch:
if o.Expr != nil {
return b.compileExprSwitch(o, parents)
}
return b.compileSwitch(o, parents)
case *dag.Join:
if len(parents) != 2 {
return nil, ErrJoinParents
}
assignments, err := b.compileAssignments(o.Args)
if err != nil {
return nil, err
}
lhs, rhs := splitAssignments(assignments)
leftKey, err := b.compileExpr(o.LeftKey)
if err != nil {
return nil, err
}
rightKey, err := b.compileExpr(o.RightKey)
if err != nil {
return nil, err
}
leftParent, rightParent := parents[0], parents[1]
leftDir, rightDir := o.LeftDir, o.RightDir
var anti, inner bool
switch o.Style {
case "anti":
anti = true
case "inner":
inner = true
case "left":
case "right":
leftKey, rightKey = rightKey, leftKey
leftParent, rightParent = rightParent, leftParent
leftDir, rightDir = rightDir, leftDir
default:
return nil, fmt.Errorf("unknown kind of join: '%s'", o.Style)
}
join, err := join.New(b.octx, anti, inner, leftParent, rightParent, leftKey, rightKey, leftDir, rightDir, lhs, rhs)
if err != nil {
return nil, err
}
return []zbuf.Puller{join}, nil
case *dag.Merge:
e, err := b.compileExpr(o.Expr)
if err != nil {
return nil, err
}
cmp := expr.NewComparator(true, o.Order == order.Desc, e).WithMissingAsNull()
return []zbuf.Puller{merge.New(b.octx, parents, cmp.Compare)}, nil
case *dag.Combine:
return []zbuf.Puller{combine.New(b.octx, parents)}, nil
default:
var parent zbuf.Puller
if len(parents) == 1 {
parent = parents[0]
} else if len(parents) > 1 {
parent = combine.New(b.octx, parents)
}
p, err := b.compileLeaf(o, parent)
if err != nil {
return nil, err
}
return []zbuf.Puller{p}, nil
}
}
func (b *Builder) compilePoolScan(scan *dag.PoolScan) (zbuf.Puller, error) {
// Here we convert PoolScan to lister->slicer->seqscan for the slow path as
// optimizer should do this conversion, but this allows us to run
// unoptimized scans too.
pool, err := b.lookupPool(scan.ID)
if err != nil {
return nil, err
}
l, err := meta.NewSortedLister(b.octx.Context, b.mctx, b.source.Lake(), pool, scan.Commit, nil)
if err != nil {
return nil, err
}
slicer := meta.NewSlicer(l, b.mctx)
return meta.NewSequenceScanner(b.octx, slicer, pool, nil, nil, b.progress), nil
}
func (b *Builder) PushdownOf(e dag.Expr) *Filter {
if e == nil {
return nil
}
return &Filter{e, b}
}
func (b *Builder) lookupPool(id ksuid.KSUID) (*lake.Pool, error) {
if b.source == nil || b.source.Lake() == nil {
return nil, errors.New("internal error: lake operation cannot be used in non-lake context")
}
// This is fast because of the pool cache in the lake.
return b.source.Lake().OpenPool(b.octx.Context, id)
}
func (b *Builder) evalAtCompileTime(in dag.Expr) (val *zed.Value, err error) {
if in == nil {
return zed.Null, nil
}
e, err := b.compileExpr(in)
if err != nil {
return nil, err
}
// Catch panic as the runtime will panic if there is a
// reference to a var not in scope, a field access null this, etc.
defer func() {
if recover() != nil {
val = b.zctx().Missing()
}
}()
return e.Eval(expr.NewContext(), b.zctx().Missing()), nil
}
func compileExpr(in dag.Expr) (expr.Evaluator, error) {
b := NewBuilder(op.NewContext(context.Background(), zed.NewContext(), nil), nil)
return b.compileExpr(in)
}
func EvalAtCompileTime(zctx *zed.Context, in dag.Expr) (val *zed.Value, err error) {
// We pass in a nil adaptor, which causes a panic for anything adaptor
// related, which is not currently allowed in an expression sub-query.
b := NewBuilder(op.NewContext(context.Background(), zctx, nil), nil)
return b.evalAtCompileTime(in)
}
func isEntry(seq dag.Seq) bool {
if len(seq) == 0 {
return false
}
switch op := seq[0].(type) {
case *Reader, *dag.Lister, *dag.FileScan, *dag.HTTPScan, *dag.PoolScan, *dag.LakeMetaScan, *dag.PoolMetaScan, *dag.CommitMetaScan:
return true
case *dag.Scope:
return isEntry(op.Body)
case *dag.Fork:
return len(op.Paths) > 0 && !slices.ContainsFunc(op.Paths, func(seq dag.Seq) bool {
return !isEntry(seq)
})
}
return false
}