/
query.go
330 lines (299 loc) · 10.6 KB
/
query.go
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// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package internal
import (
"reflect"
"strconv"
"sync"
ds "v.io/v23/query/engine/datasource"
"v.io/v23/query/engine/internal/querychecker"
"v.io/v23/query/engine/internal/queryfunctions"
"v.io/v23/query/engine/internal/queryparser"
"v.io/v23/query/engine/public"
"v.io/v23/query/syncql"
"v.io/v23/vdl"
"v.io/v23/vom"
)
type queryEngineImpl struct {
db ds.Database
mutexNextID sync.Mutex
nextID int64
mutexPreparedStatements sync.Mutex
preparedStatements map[int64]*queryparser.Statement
}
type preparedStatementImpl struct {
qe *queryEngineImpl
id int64 // key to AST stored in queryEngineImpl.
}
func Create(db ds.Database) public.QueryEngine {
return &queryEngineImpl{db: db, nextID: 0, preparedStatements: map[int64]*queryparser.Statement{}}
}
func (qe *queryEngineImpl) Exec(q string) ([]string, syncql.ResultStream, error) {
return Exec(qe.db, q)
}
func (qe *queryEngineImpl) GetPreparedStatement(handle int64) (public.PreparedStatement, error) {
qe.mutexPreparedStatements.Lock()
_, ok := qe.preparedStatements[handle]
qe.mutexPreparedStatements.Unlock()
if ok {
return &preparedStatementImpl{qe, handle}, nil
}
return nil, syncql.ErrorfPreparedStatementNotFound(qe.db.GetContext(), "[0]prepared statement not found")
}
func (qe *queryEngineImpl) PrepareStatement(q string) (public.PreparedStatement, error) {
s, err := queryparser.Parse(qe.db, q)
if err != nil {
return nil, err
}
qe.mutexNextID.Lock()
id := qe.nextID
qe.nextID++
qe.mutexNextID.Unlock()
qe.mutexPreparedStatements.Lock()
qe.preparedStatements[id] = s
qe.mutexPreparedStatements.Unlock()
return &preparedStatementImpl{qe, id}, nil
}
func (p *preparedStatementImpl) Exec(paramValues ...*vom.RawBytes) ([]string, syncql.ResultStream, error) {
// Find the AST
p.qe.mutexPreparedStatements.Lock()
s := p.qe.preparedStatements[p.id]
p.qe.mutexPreparedStatements.Unlock()
vvs := make([]*vdl.Value, len(paramValues))
for i := range paramValues {
if err := paramValues[i].ToValue(&vvs[i]); err != nil {
return nil, nil, err
}
}
// Copy the AST and substitute any parameters with actual values.
// Note: Not all of the AST is copied as most parts are immutable.
sCopy, err := (*s).CopyAndSubstitute(p.qe.db, vvs)
if err != nil {
return nil, nil, err
}
// Sematnically check the copied AST and then execute it.
return checkAndExec(p.qe.db, &sCopy)
}
func (p *preparedStatementImpl) Handle() int64 {
return p.id
}
func (p *preparedStatementImpl) Close() {
p.qe.mutexPreparedStatements.Lock()
delete(p.qe.preparedStatements, p.id)
p.qe.mutexPreparedStatements.Unlock()
}
func Exec(db ds.Database, q string) ([]string, syncql.ResultStream, error) {
s, err := queryparser.Parse(db, q)
if err != nil {
return nil, nil, err
}
return checkAndExec(db, s)
}
func checkAndExec(db ds.Database, s *queryparser.Statement) ([]string, syncql.ResultStream, error) {
if err := querychecker.Check(db, s); err != nil {
return nil, nil, err
}
switch (*s).(type) {
case queryparser.SelectStatement, queryparser.DeleteStatement:
return execStatement(db, s)
default:
return nil, nil, syncql.ErrorfExecOfUnknownStatementType(db.GetContext(), "[%v]cannot execute unknown statement type: %v", (*s).Offset(), reflect.TypeOf(*s).Name())
}
}
// Given a key, a value and a SelectClause, return the projection.
// This function is only called if Eval returned true on the WhereClause expression.
func ComposeProjection(db ds.Database, k string, v *vdl.Value, s *queryparser.SelectClause) []*vom.RawBytes {
var projection []*vom.RawBytes
for _, selector := range s.Selectors {
switch selector.Type {
case queryparser.TypSelField:
// If field not found, nil is returned (as per specification).
f := ResolveField(db, k, v, selector.Field)
projection = append(projection, vom.RawBytesOf(f))
case queryparser.TypSelFunc:
if selector.Function.Computed {
projection = append(projection, queryfunctions.ConvertFunctionRetValueToRawBytes(selector.Function.RetValue))
} else {
// need to exec function
// If error executing function, return nil (as per specification).
retValue, err := resolveArgsAndExecFunction(db, k, v, selector.Function)
if err != nil {
retValue = nil
}
projection = append(projection, queryfunctions.ConvertFunctionRetValueToRawBytes(retValue))
}
}
}
return projection
}
// For testing purposes, given a SelectStatement, k and v;
// return nil if row not selected, else return the projection (type []*vdl.Value).
// Note: limit and offset clauses are ignored for this function as they make no sense
// for a single row.
func ExecSelectSingleRow(db ds.Database, k string, v *vdl.Value, s *queryparser.SelectStatement) []*vom.RawBytes {
if !Eval(db, k, v, s.Where.Expr) {
rs := []*vom.RawBytes{}
return rs
}
return ComposeProjection(db, k, v, s.Select)
}
func getColumnHeadings(s *queryparser.SelectStatement) []string {
columnHeaders := []string{}
for _, selector := range s.Select.Selectors {
columnName := ""
if selector.As != nil {
columnName = selector.As.AltName.Value
} else {
switch selector.Type {
case queryparser.TypSelField:
sep := ""
for _, segment := range selector.Field.Segments {
columnName = columnName + sep + segment.Value
for _, key := range segment.Keys {
columnName += getSegmentKeyAsHeading(key)
}
sep = "."
}
case queryparser.TypSelFunc:
columnName = selector.Function.Name
}
}
columnHeaders = append(columnHeaders, columnName)
}
return columnHeaders
}
// TODO(jkline): Should we really include key/index of a map/set/array/list in the header?
// The column names can get quite long. Perhaps just "[]" at the end of the segment
// would be better. The author of the query can always use the As clause to specify a
// better heading. Note: for functions, just the function name is included in the header.
// When a decision is made, it's best to be consistent for functions and key/indexes.
func getSegmentKeyAsHeading(segKey *queryparser.Operand) string {
val := "["
switch segKey.Type {
case queryparser.TypBigInt:
val += segKey.BigInt.String()
case queryparser.TypBigRat:
val += segKey.BigRat.String()
case queryparser.TypField:
sep := ""
for _, segment := range segKey.Column.Segments {
val += sep + segment.Value
for _, key := range segment.Keys {
val += getSegmentKeyAsHeading(key)
}
sep = "."
}
case queryparser.TypBool:
val += strconv.FormatBool(segKey.Bool)
case queryparser.TypInt:
val += strconv.FormatInt(segKey.Int, 10)
case queryparser.TypFloat:
val += strconv.FormatFloat(segKey.Float, 'f', -1, 64)
case queryparser.TypFunction:
val += segKey.Function.Name
case queryparser.TypStr:
val += segKey.Str
case queryparser.TypTime:
val += segKey.Time.Format("Mon Jan 2 15:04:05 -0700 MST 2006")
case queryparser.TypNil:
val += "<nil>"
case queryparser.TypObject:
val += "<object>"
default:
val += "<?>"
}
val += "]"
return val
}
func getIndexRanges(db ds.Database, tableName string, tableOff int64, indexFields []ds.Index, w *queryparser.WhereClause) ([]ds.IndexRanges, error) {
indexes := []ds.IndexRanges{}
// Get IndexRanges for k
kfield := &queryparser.Field{Segments: []queryparser.Segment{{Value: "k"}}}
idxRanges := *querychecker.CompileIndexRanges(kfield, vdl.String, w)
indexes = append(indexes, idxRanges)
// Get IndexRanges for secondary indexes.
for _, idx := range indexFields {
if idx.Kind != vdl.String {
return nil, syncql.ErrorfIndexKindNotSupported(db.GetContext(), "[%v]Index kind %v of field %v on table %v not supported.", tableOff, idx.Kind.String(), idx.FieldName, tableName)
}
var err error
var idxField *queryparser.Field
// Construct a Field from the string. Use the parser as it knows best.
if idxField, err = queryparser.ParseIndexField(db, idx.FieldName, tableName); err != nil {
return nil, err
}
idxRanges := *querychecker.CompileIndexRanges(idxField, idx.Kind, w)
indexes = append(indexes, idxRanges)
}
return indexes, nil
}
func execStatement(db ds.Database, s *queryparser.Statement) ([]string, syncql.ResultStream, error) { //nolint:gocyclo
switch st := (*s).(type) {
// Select
case queryparser.SelectStatement:
indexes, err := getIndexRanges(db, st.From.Table.Name, st.From.Table.Off, st.From.Table.DBTable.GetIndexFields(), st.Where)
if err != nil {
return nil, nil, err
}
keyValueStream, err := st.From.Table.DBTable.Scan(indexes...)
if err != nil {
return nil, nil, syncql.ErrorfScanError(db.GetContext(), "[%v]scan error: %v", st.Off, err)
}
var resultStream selectResultStreamImpl
resultStream.db = db
resultStream.selectStatement = &st
resultStream.keyValueStream = keyValueStream
return getColumnHeadings(&st), &resultStream, nil
// Delete
case queryparser.DeleteStatement:
indexes, err := getIndexRanges(db, st.From.Table.Name, st.From.Table.Off, st.From.Table.DBTable.GetIndexFields(), st.Where)
if err != nil {
return nil, nil, err
}
keyValueStream, err := st.From.Table.DBTable.Scan(indexes...)
if err != nil {
return nil, nil, syncql.ErrorfScanError(db.GetContext(), "[%v]scan error: %v", st.Off, err)
}
deleteCount := int64(0)
for keyValueStream.Advance() {
if st.Limit != nil && deleteCount >= st.Limit.Limit.Value {
defer keyValueStream.Cancel()
break
}
k, v := keyValueStream.KeyValue()
// EvalWhereUsingOnlyKey
// INCLUDE: the row should be included in the results
// EXCLUDE: the row should NOT be included
// FETCH_VALUE: the value and/or type of the value are required to make determination.
rv := EvalWhereUsingOnlyKey(db, st.Where, k)
var match bool
switch rv {
case Include:
match = true
case Exclude:
match = false
case FetchValue:
match = Eval(db, k, vdl.ValueOf(v), st.Where.Expr)
}
if match {
b, err := st.From.Table.DBTable.Delete(k)
// May not have delete permission to delete this k/v pair.
// Continue, but don't increment delete count.
if err == nil && b {
deleteCount++
}
}
}
if err := keyValueStream.Err(); err != nil {
return nil, nil, syncql.ErrorfKeyValueStreamError(db.GetContext(), "[%v]KeyValueStream error: %v", st.Off, err)
}
var resultStream deleteResultStreamImpl
resultStream.db = db
resultStream.deleteStatement = &st
resultStream.deleteCursor = 0
resultStream.deleteCount = deleteCount
return []string{"Count"}, &resultStream, nil
}
return nil, nil, syncql.ErrorfOperationNotSupported(db.GetContext(), "[0]%v not supported.", "uknown")
}