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engine.go
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// Copyright 2020-2021 Dolthub, Inc.
//
// Licensed 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 sqle
import (
"fmt"
"os"
"sync"
"github.com/pkg/errors"
"github.com/dolthub/go-mysql-server/memory"
"github.com/dolthub/go-mysql-server/sql"
"github.com/dolthub/go-mysql-server/sql/analyzer"
"github.com/dolthub/go-mysql-server/sql/expression"
"github.com/dolthub/go-mysql-server/sql/expression/function"
"github.com/dolthub/go-mysql-server/sql/parse"
"github.com/dolthub/go-mysql-server/sql/plan"
"github.com/dolthub/go-mysql-server/sql/planbuilder"
"github.com/dolthub/go-mysql-server/sql/rowexec"
"github.com/dolthub/go-mysql-server/sql/transform"
_ "github.com/dolthub/go-mysql-server/sql/variables"
)
const experimentalFlag = "GMS_EXPERIMENTAL"
var ExperimentalGMS bool
func init() {
ExperimentalGMS = os.Getenv(experimentalFlag) != ""
}
// Config for the Engine.
type Config struct {
// VersionPostfix to display with the `VERSION()` UDF.
VersionPostfix string
// IsReadOnly sets the engine to disallow modification queries.
IsReadOnly bool
IsServerLocked bool
// IncludeRootAccount adds the root account (with no password) to the list of accounts, and also enables
// authentication.
IncludeRootAccount bool
// TemporaryUsers adds any users that should be included when the engine is created. By default, authentication is
// disabled, and including any users here will enable authentication. All users in this list will have full access.
// This field is only temporary, and will be removed as development on users and authentication continues.
TemporaryUsers []TemporaryUser
}
// TemporaryUser is a user that will be added to the engine. This is for temporary use while the remaining features
// are implemented. Replaces the old "auth.New..." functions for adding a user.
type TemporaryUser struct {
Username string
Password string
}
// PreparedDataCache manages all the prepared data for every session for every query for an engine
type PreparedDataCache struct {
data map[uint32]map[string]sql.Node
mu *sync.Mutex
}
func NewPreparedDataCache() *PreparedDataCache {
return &PreparedDataCache{
data: make(map[uint32]map[string]sql.Node),
mu: &sync.Mutex{},
}
}
// GetCachedStmt will retrieve the prepared sql.Node associated with the ctx.SessionId and query if it exists
// it will return nil, false if the query does not exist
func (p *PreparedDataCache) GetCachedStmt(sessId uint32, query string) (sql.Node, bool) {
p.mu.Lock()
defer p.mu.Unlock()
if sessData, ok := p.data[sessId]; ok {
data, ok := sessData[query]
return data, ok
}
return nil, false
}
// GetSessionData returns all the prepared queries for a particular session
func (p *PreparedDataCache) GetSessionData(sessId uint32) map[string]sql.Node {
p.mu.Lock()
defer p.mu.Unlock()
return p.data[sessId]
}
// DeleteSessionData clears a session along with all prepared queries for that session
func (p *PreparedDataCache) DeleteSessionData(sessId uint32) {
p.mu.Lock()
defer p.mu.Unlock()
delete(p.data, sessId)
}
// CacheStmt saves the prepared node and associates a ctx.SessionId and query to it
func (p *PreparedDataCache) CacheStmt(sessId uint32, query string, node sql.Node) {
p.mu.Lock()
defer p.mu.Unlock()
if _, ok := p.data[sessId]; !ok {
p.data[sessId] = make(map[string]sql.Node)
}
p.data[sessId][query] = node
}
// UncacheStmt removes the prepared node associated with a ctx.SessionId and query to it
func (p *PreparedDataCache) UncacheStmt(sessId uint32, query string) {
p.mu.Lock()
defer p.mu.Unlock()
if _, ok := p.data[sessId]; !ok {
return
}
delete(p.data[sessId], query)
}
// Engine is a SQL engine.
type Engine struct {
Analyzer *analyzer.Analyzer
LS *sql.LockSubsystem
ProcessList sql.ProcessList
MemoryManager *sql.MemoryManager
BackgroundThreads *sql.BackgroundThreads
IsReadOnly bool
IsServerLocked bool
PreparedDataCache *PreparedDataCache
mu *sync.Mutex
Version sql.AnalyzerVersion
}
type ColumnWithRawDefault struct {
SqlColumn *sql.Column
Default string
}
// New creates a new Engine with custom configuration. To create an Engine with
// the default settings use `NewDefault`. Should call Engine.Close() to finalize
// dependency lifecycles.
func New(a *analyzer.Analyzer, cfg *Config) *Engine {
if cfg == nil {
cfg = &Config{}
}
if cfg.IncludeRootAccount {
a.Catalog.MySQLDb.AddRootAccount()
}
ls := sql.NewLockSubsystem()
emptyCtx := sql.NewEmptyContext()
a.Catalog.RegisterFunction(emptyCtx, sql.FunctionN{
Name: "version",
Fn: function.NewVersion(cfg.VersionPostfix),
})
a.Catalog.RegisterFunction(emptyCtx, function.GetLockingFuncs(ls)...)
version := sql.VersionStable
if ExperimentalGMS {
version = sql.VersionExperimental
}
return &Engine{
Analyzer: a,
MemoryManager: sql.NewMemoryManager(sql.ProcessMemory),
ProcessList: NewProcessList(),
LS: ls,
BackgroundThreads: sql.NewBackgroundThreads(),
IsReadOnly: cfg.IsReadOnly,
IsServerLocked: cfg.IsServerLocked,
PreparedDataCache: NewPreparedDataCache(),
mu: &sync.Mutex{},
Version: version,
}
}
// NewDefault creates a new default Engine.
func NewDefault(pro sql.DatabaseProvider) *Engine {
version := sql.VersionStable
if ExperimentalGMS {
version = sql.VersionExperimental
}
a := analyzer.NewDefaultWithVersion(pro, version)
return New(a, nil)
}
// AnalyzeQuery analyzes a query and returns its sql.Node
func (e *Engine) AnalyzeQuery(
ctx *sql.Context,
query string,
) (sql.Node, error) {
if ctx.Version == sql.VersionUnknown {
ctx.Version = e.Version
}
var parsed sql.Node
var err error
switch ctx.Version {
case sql.VersionExperimental:
parsed, err = planbuilder.Parse(ctx, e.Analyzer.Catalog, query)
if err != nil {
ctx.Version = sql.VersionStable
parsed, err = parse.Parse(ctx, query)
}
default:
parsed, err = parse.Parse(ctx, query)
}
if err != nil {
return nil, err
}
return e.Analyzer.Analyze(ctx, parsed, nil)
}
// PrepareQuery returns a partially analyzed query
func (e *Engine) PrepareQuery(
ctx *sql.Context,
query string,
) (sql.Node, error) {
parsed, err := parse.Parse(ctx, query)
if err != nil {
return nil, err
}
node, err := e.Analyzer.PrepareQuery(ctx, parsed, nil)
if err != nil {
return nil, err
}
e.PreparedDataCache.CacheStmt(ctx.Session.ID(), query, node)
return node, nil
}
// Query executes a query.
func (e *Engine) Query(ctx *sql.Context, query string) (sql.Schema, sql.RowIter, error) {
return e.QueryWithBindings(ctx, query, nil)
}
// QueryWithBindings executes the query given with the bindings provided
func (e *Engine) QueryWithBindings(ctx *sql.Context, query string, bindings map[string]sql.Expression) (sql.Schema, sql.RowIter, error) {
return e.QueryNodeWithBindings(ctx, query, nil, bindings)
}
// QueryNodeWithBindings executes the query given with the bindings provided. If parsed is non-nil, it will be used
// instead of parsing the query from text.
func (e *Engine) QueryNodeWithBindings(ctx *sql.Context, query string, parsed sql.Node, bindings map[string]sql.Expression) (sql.Schema, sql.RowIter, error) {
var (
analyzed sql.Node
iter sql.RowIter
err error
)
if ctx.Version == sql.VersionUnknown {
ctx.Version = e.Version
}
if parsed == nil {
switch ctx.Version {
case sql.VersionExperimental:
parsed, err = planbuilder.Parse(ctx, e.Analyzer.Catalog, query)
default:
parsed, err = parse.Parse(ctx, query)
}
if err != nil {
return nil, nil, err
}
}
// Give the integrator a chance to reject the session before proceeding
err = ctx.Session.ValidateSession(ctx)
if err != nil {
return nil, nil, err
}
err = e.readOnlyCheck(parsed)
if err != nil {
return nil, nil, err
}
err = e.beginTransaction(ctx)
if err != nil {
return nil, nil, err
}
if p, ok := e.PreparedDataCache.GetCachedStmt(ctx.Session.ID(), query); ok {
analyzed, err = e.analyzePreparedQuery(ctx, query, p, bindings)
} else {
analyzed, err = e.analyzeQuery(ctx, query, parsed, bindings)
}
if err != nil {
err2 := clearAutocommitTransaction(ctx)
if err2 != nil {
err = errors.Wrap(err, "unable to clear autocommit transaction: "+err2.Error())
}
return nil, nil, err
}
iter, err = e.Analyzer.ExecBuilder.Build(ctx, analyzed, nil)
if err != nil {
err2 := clearAutocommitTransaction(ctx)
if err2 != nil {
err = errors.Wrap(err, "unable to clear autocommit transaction: "+err2.Error())
}
return nil, nil, err
}
iter = rowexec.AddExpressionCloser(analyzed, iter)
return analyzed.Schema(), iter, nil
}
// clearAutocommitTransaction unsets the transaction from the current session if it is an implicitly
// created autocommit transaction. This enables the next request to have an autocommit transaction
// correctly started.
func clearAutocommitTransaction(ctx *sql.Context) error {
// The GetIgnoreAutoCommit property essentially says the current transaction is an explicit,
// user-created transaction and we should not process autocommit. So, if it's set, then we
// don't need to do anything here to clear implicit transaction state.
//
// TODO: This logic would probably read more clearly if we could just ask the session/ctx if the
// current transaction is automatically created or explicitly created by the caller.
if ctx.GetIgnoreAutoCommit() {
return nil
}
autocommit, err := plan.IsSessionAutocommit(ctx)
if err != nil {
return err
}
if autocommit {
ctx.SetTransaction(nil)
}
return nil
}
// CloseSession deletes session specific prepared statement data
func (e *Engine) CloseSession(connID uint32) {
e.mu.Lock()
defer e.mu.Unlock()
e.PreparedDataCache.DeleteSessionData(connID)
}
// Count number of BindVars in given tree
func countBindVars(node sql.Node) int {
var bindVars map[string]bool
bindCntFunc := func(e sql.Expression) bool {
if bv, ok := e.(*expression.BindVar); ok {
if bindVars == nil {
bindVars = make(map[string]bool)
}
bindVars[bv.Name] = true
}
return true
}
transform.InspectExpressions(node, bindCntFunc)
// InsertInto.Source not a child of InsertInto, so also need to traverse those
transform.Inspect(node, func(n sql.Node) bool {
if in, ok := n.(*plan.InsertInto); ok {
transform.InspectExpressions(in.Source, bindCntFunc)
return false
}
return true
})
return len(bindVars)
}
func (e *Engine) analyzeQuery(ctx *sql.Context, query string, parsed sql.Node, bindings map[string]sql.Expression) (sql.Node, error) {
var (
analyzed sql.Node
err error
)
// TODO: eventually, we should have this logic be in the RowIter() of the respective plans
// along with a new rule that handles analysis
switch n := parsed.(type) {
case *plan.PrepareQuery:
analyzedChild, err := e.Analyzer.PrepareQuery(ctx, n.Child, nil)
if err != nil {
return nil, err
}
e.PreparedDataCache.CacheStmt(ctx.Session.ID(), n.Name, analyzedChild)
return parsed, nil
case *plan.ExecuteQuery:
// replace execute query node with the one prepared
p, ok := e.PreparedDataCache.GetCachedStmt(ctx.Session.ID(), n.Name)
if !ok {
return nil, sql.ErrUnknownPreparedStatement.New(n.Name)
}
// number of BindVars provided must match number of BindVars expected
if countBindVars(p) != len(n.BindVars) {
return nil, sql.ErrInvalidArgument.New(n.Name)
}
parsed = p
bindings = map[string]sql.Expression{}
for i, binding := range n.BindVars {
varName := fmt.Sprintf("v%d", i+1)
bindings[varName] = binding
}
if len(bindings) > 0 {
var usedBindings map[string]bool
parsed, usedBindings, err = plan.ApplyBindings(parsed, bindings)
if err != nil {
return nil, err
}
for binding := range bindings {
if !usedBindings[binding] && !plan.HasEmptyTable(analyzed) {
return nil, fmt.Errorf("unused binding %s", binding)
}
}
}
analyzed, _, err = e.Analyzer.AnalyzePrepared(ctx, parsed, nil)
if err != nil {
return nil, err
}
return analyzed, nil
case *plan.DeallocateQuery:
if _, ok := e.PreparedDataCache.GetCachedStmt(ctx.Session.ID(), n.Name); !ok {
return nil, sql.ErrUnknownPreparedStatement.New(n.Name)
}
e.PreparedDataCache.UncacheStmt(ctx.Session.ID(), n.Name)
return parsed, nil
}
if len(bindings) > 0 {
var usedBindings map[string]bool
parsed, usedBindings, err = plan.ApplyBindings(parsed, bindings)
if err != nil {
return nil, err
}
for binding := range bindings {
if !usedBindings[binding] && !plan.HasEmptyTable(analyzed) {
return nil, fmt.Errorf("unused binding %s", binding)
}
}
}
analyzed, err = e.Analyzer.Analyze(ctx, parsed, nil)
if err != nil {
return nil, err
}
return analyzed, nil
}
func (e *Engine) analyzePreparedQuery(ctx *sql.Context, query string, analyzed sql.Node, bindings map[string]sql.Expression) (sql.Node, error) {
ctx.GetLogger().Tracef("optimizing prepared plan for query: %s", query)
analyzed, err := analyzer.DeepCopyNode(analyzed)
if err != nil {
return nil, err
}
if len(bindings) > 0 {
var usedBindings map[string]bool
analyzed, usedBindings, err = plan.ApplyBindings(analyzed, bindings)
if err != nil {
return nil, err
}
for binding := range bindings {
if !usedBindings[binding] && !plan.HasEmptyTable(analyzed) {
return nil, fmt.Errorf("unused binding %s", binding)
}
}
}
ctx.GetLogger().Tracef("plan before re-opt: %s", analyzed.String())
analyzed, _, err = e.Analyzer.AnalyzePrepared(ctx, analyzed, nil)
if err != nil {
return nil, err
}
ctx.GetLogger().Tracef("plan after re-opt: %s", analyzed.String())
return analyzed, nil
}
func (e *Engine) beginTransaction(ctx *sql.Context) error {
beginNewTransaction := ctx.GetTransaction() == nil || plan.ReadCommitted(ctx)
if beginNewTransaction {
ctx.GetLogger().Tracef("beginning new transaction")
ts, ok := ctx.Session.(sql.TransactionSession)
if ok {
tx, err := ts.StartTransaction(ctx, sql.ReadWrite)
if err != nil {
return err
}
ctx.SetTransaction(tx)
}
}
return nil
}
func (e *Engine) Close() error {
for _, p := range e.ProcessList.Processes() {
e.ProcessList.Kill(p.Connection)
}
return e.BackgroundThreads.Shutdown()
}
func (e *Engine) WithBackgroundThreads(b *sql.BackgroundThreads) *Engine {
e.BackgroundThreads = b
return e
}
// readOnlyCheck checks to see if the query is valid with the modification setting of the engine.
func (e *Engine) readOnlyCheck(node sql.Node) error {
if plan.IsDDLNode(node) {
if e.IsReadOnly {
return sql.ErrReadOnly.New()
} else if e.IsServerLocked {
return sql.ErrDatabaseWriteLocked.New()
}
}
switch node.(type) {
case
*plan.DeleteFrom, *plan.InsertInto, *plan.Update, *plan.LockTables, *plan.UnlockTables:
if e.IsReadOnly {
return sql.ErrReadOnly.New()
} else if e.IsServerLocked {
return sql.ErrDatabaseWriteLocked.New()
}
}
return nil
}
// ResolveDefaults takes in a schema, along with each column's default value in a string form, and returns the schema
// with the default values parsed and resolved.
func ResolveDefaults(tableName string, schema []*ColumnWithRawDefault) (sql.Schema, error) {
// todo: change this function or thread a context
ctx := sql.NewEmptyContext()
db := plan.NewDummyResolvedDB("temporary")
e := NewDefault(memory.NewDBProvider(db))
defer e.Close()
unresolvedSchema := make(sql.Schema, len(schema))
defaultCount := 0
for i, col := range schema {
unresolvedSchema[i] = col.SqlColumn
if col.Default != "" {
var err error
unresolvedSchema[i].Default, err = parse.StringToColumnDefaultValue(ctx, col.Default)
if err != nil {
return nil, err
}
defaultCount++
}
}
// if all defaults are nil, we can skip the rest of this
if defaultCount == 0 {
return unresolvedSchema, nil
}
// *plan.CreateTable properly handles resolving default values, so we hijack it
createTable := plan.NewCreateTable(db, tableName, false, false, &plan.TableSpec{Schema: sql.NewPrimaryKeySchema(unresolvedSchema)})
analyzed, err := e.Analyzer.Analyze(ctx, createTable, nil)
if err != nil {
return nil, err
}
analyzedQueryProcess, ok := analyzed.(*plan.QueryProcess)
if !ok {
return nil, fmt.Errorf("internal error: unknown analyzed result type `%T`", analyzed)
}
analyzedCreateTable, ok := analyzedQueryProcess.Child().(*plan.CreateTable)
if !ok {
return nil, fmt.Errorf("internal error: unknown query process child type `%T`", analyzedQueryProcess)
}
return analyzedCreateTable.CreateSchema.Schema, nil
}
// ColumnsFromCheckDefinition retrieves the Column Names referenced by a CheckDefinition
func ColumnsFromCheckDefinition(ctx *sql.Context, def *sql.CheckDefinition) ([]string, error) {
// Evaluate the CheckDefinition to get evaluated Expression
c, err := analyzer.ConvertCheckDefToConstraint(ctx, def, nil)
if err != nil {
return nil, err
}
// Look for any column references in the evaluated Expression
var cols []string
sql.Inspect(c.Expr, func(expr sql.Expression) bool {
if c, ok := expr.(*expression.UnresolvedColumn); ok {
cols = append(cols, c.Name())
return false
}
return true
})
return cols, nil
}