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reader.go
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/
reader.go
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package metadata
import (
"context"
"database/sql"
"time"
"github.com/xo/usql/text"
)
// PluginReader allows to be easily composed from other readers
type PluginReader struct {
catalogs func(Filter) (*CatalogSet, error)
schemas func(Filter) (*SchemaSet, error)
tables func(Filter) (*TableSet, error)
columns func(Filter) (*ColumnSet, error)
columnStats func(Filter) (*ColumnStatSet, error)
indexes func(Filter) (*IndexSet, error)
indexColumns func(Filter) (*IndexColumnSet, error)
triggers func(Filter) (*TriggerSet, error)
constraints func(Filter) (*ConstraintSet, error)
constraintColumns func(Filter) (*ConstraintColumnSet, error)
functions func(Filter) (*FunctionSet, error)
functionColumns func(Filter) (*FunctionColumnSet, error)
sequences func(Filter) (*SequenceSet, error)
privilegeSummaries func(Filter) (*PrivilegeSummarySet, error)
}
var _ ExtendedReader = &PluginReader{}
// NewPluginReader allows to be easily composed from other readers
func NewPluginReader(readers ...Reader) Reader {
p := PluginReader{}
for _, i := range readers {
if r, ok := i.(CatalogReader); ok {
p.catalogs = r.Catalogs
}
if r, ok := i.(SchemaReader); ok {
p.schemas = r.Schemas
}
if r, ok := i.(TableReader); ok {
p.tables = r.Tables
}
if r, ok := i.(ColumnReader); ok {
p.columns = r.Columns
}
if r, ok := i.(ColumnStatReader); ok {
p.columnStats = r.ColumnStats
}
if r, ok := i.(IndexReader); ok {
p.indexes = r.Indexes
}
if r, ok := i.(IndexColumnReader); ok {
p.indexColumns = r.IndexColumns
}
if r, ok := i.(TriggerReader); ok {
p.triggers = r.Triggers
}
if r, ok := i.(ConstraintReader); ok {
p.constraints = r.Constraints
}
if r, ok := i.(ConstraintColumnReader); ok {
p.constraintColumns = r.ConstraintColumns
}
if r, ok := i.(FunctionReader); ok {
p.functions = r.Functions
}
if r, ok := i.(FunctionColumnReader); ok {
p.functionColumns = r.FunctionColumns
}
if r, ok := i.(SequenceReader); ok {
p.sequences = r.Sequences
}
if r, ok := i.(PrivilegeSummaryReader); ok {
p.privilegeSummaries = r.PrivilegeSummaries
}
}
return &p
}
func (p PluginReader) Catalogs(f Filter) (*CatalogSet, error) {
if p.catalogs == nil {
return nil, text.ErrNotSupported
}
return p.catalogs(f)
}
func (p PluginReader) Schemas(f Filter) (*SchemaSet, error) {
if p.schemas == nil {
return nil, text.ErrNotSupported
}
return p.schemas(f)
}
func (p PluginReader) Tables(f Filter) (*TableSet, error) {
if p.tables == nil {
return nil, text.ErrNotSupported
}
return p.tables(f)
}
func (p PluginReader) Columns(f Filter) (*ColumnSet, error) {
if p.columns == nil {
return nil, text.ErrNotSupported
}
return p.columns(f)
}
func (p PluginReader) ColumnStats(f Filter) (*ColumnStatSet, error) {
if p.columnStats == nil {
return nil, text.ErrNotSupported
}
return p.columnStats(f)
}
func (p PluginReader) Indexes(f Filter) (*IndexSet, error) {
if p.indexes == nil {
return nil, text.ErrNotSupported
}
return p.indexes(f)
}
func (p PluginReader) IndexColumns(f Filter) (*IndexColumnSet, error) {
if p.indexColumns == nil {
return nil, text.ErrNotSupported
}
return p.indexColumns(f)
}
func (p PluginReader) Triggers(f Filter) (*TriggerSet, error) {
if p.triggers == nil {
return nil, text.ErrNotSupported
}
return p.triggers(f)
}
func (p PluginReader) Constraints(f Filter) (*ConstraintSet, error) {
if p.constraints == nil {
return nil, text.ErrNotSupported
}
return p.constraints(f)
}
func (p PluginReader) ConstraintColumns(f Filter) (*ConstraintColumnSet, error) {
if p.constraintColumns == nil {
return nil, text.ErrNotSupported
}
return p.constraintColumns(f)
}
func (p PluginReader) Functions(f Filter) (*FunctionSet, error) {
if p.functions == nil {
return nil, text.ErrNotSupported
}
return p.functions(f)
}
func (p PluginReader) FunctionColumns(f Filter) (*FunctionColumnSet, error) {
if p.functionColumns == nil {
return nil, text.ErrNotSupported
}
return p.functionColumns(f)
}
func (p PluginReader) Sequences(f Filter) (*SequenceSet, error) {
if p.sequences == nil {
return nil, text.ErrNotSupported
}
return p.sequences(f)
}
func (p PluginReader) PrivilegeSummaries(f Filter) (*PrivilegeSummarySet, error) {
if p.privilegeSummaries == nil {
return nil, text.ErrNotSupported
}
return p.privilegeSummaries(f)
}
type LoggingReader struct {
db DB
logger logger
dryRun bool
timeout time.Duration
}
type logger interface {
Println(...interface{})
}
func NewLoggingReader(db DB, opts ...ReaderOption) LoggingReader {
r := LoggingReader{
db: db,
}
for _, o := range opts {
o(&r)
}
return r
}
// ReaderOption to configure the reader
type ReaderOption func(Reader)
// WithLogger used to log queries before executing them
func WithLogger(l logger) ReaderOption {
return func(r Reader) {
r.(loggerSetter).setLogger(l)
}
}
// WithDryRun allows to avoid running any queries
func WithDryRun(d bool) ReaderOption {
return func(r Reader) {
r.(loggerSetter).setDryRun(d)
}
}
// WithTimeout for a single query
func WithTimeout(t time.Duration) ReaderOption {
return func(r Reader) {
r.(loggerSetter).setTimeout(t)
}
}
// WithLimit for a single query, if the reader supports it
func WithLimit(l int) ReaderOption {
return func(r Reader) {
if rl, ok := r.(limiter); ok {
rl.SetLimit(l)
}
}
}
type loggerSetter interface {
setLogger(logger)
setDryRun(bool)
setTimeout(t time.Duration)
}
type limiter interface {
SetLimit(l int)
}
func (r *LoggingReader) setLogger(l logger) {
r.logger = l
}
func (r *LoggingReader) setDryRun(d bool) {
r.dryRun = d
}
func (r *LoggingReader) setTimeout(t time.Duration) {
r.timeout = t
}
func (r LoggingReader) Query(q string, v ...interface{}) (*sql.Rows, CloseFunc, error) {
if r.logger != nil {
r.logger.Println(q)
r.logger.Println(v)
}
if r.dryRun {
return nil, nil, sql.ErrNoRows
}
if r.timeout != 0 {
ctx, cancel := context.WithTimeout(context.Background(), r.timeout)
rows, err := r.db.QueryContext(ctx, q, v...)
return rows, func() { cancel(); rows.Close() }, err
}
rows, err := r.db.Query(q, v...)
return rows, func() { rows.Close() }, err
}
// CloseFunc should be called when result wont be processed anymore
type CloseFunc func()