|
|
|
package db
|
|
|
|
|
|
|
|
import (
|
|
|
|
"database/sql"
|
|
|
|
"fmt"
|
|
|
|
"os"
|
|
|
|
"path/filepath"
|
|
|
|
"testing"
|
|
|
|
"time"
|
|
|
|
)
|
|
|
|
|
|
|
|
func Test_IsValidSQLiteOnDisk(t *testing.T) {
|
|
|
|
path := mustTempFile()
|
|
|
|
defer os.Remove(path)
|
|
|
|
|
|
|
|
dsn := fmt.Sprintf("file:%s", path)
|
|
|
|
db, err := sql.Open("sqlite3", dsn)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to create SQLite database: %s", err.Error())
|
|
|
|
}
|
|
|
|
_, err = db.Exec("CREATE TABLE foo (name TEXT)")
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to create table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if err := db.Close(); err != nil {
|
|
|
|
t.Fatalf("failed to close database: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
if !IsValidSQLiteFile(path) {
|
|
|
|
t.Fatalf("good SQLite file marked as invalid")
|
|
|
|
}
|
|
|
|
|
|
|
|
data, err := os.ReadFile(path)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to read SQLite file: %s", err.Error())
|
|
|
|
}
|
|
|
|
if !IsValidSQLiteData(data) {
|
|
|
|
t.Fatalf("good SQLite data marked as invalid")
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
func Test_IsWALModeEnabledOnDiskDELETE(t *testing.T) {
|
|
|
|
path := mustTempFile()
|
|
|
|
defer os.Remove(path)
|
|
|
|
|
|
|
|
dsn := fmt.Sprintf("file:%s", path)
|
|
|
|
db, err := sql.Open("sqlite3", dsn)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to create SQLite database: %s", err.Error())
|
|
|
|
}
|
|
|
|
_, err = db.Exec("CREATE TABLE foo (name TEXT)")
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to create table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if err := db.Close(); err != nil {
|
|
|
|
t.Fatalf("failed to close database: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
if !IsDELETEModeEnabledSQLiteFile(path) {
|
|
|
|
t.Fatalf("DELETE file marked as non-DELETE")
|
|
|
|
}
|
|
|
|
if IsWALModeEnabledSQLiteFile(path) {
|
|
|
|
t.Fatalf("non WAL file marked as WAL")
|
|
|
|
}
|
|
|
|
|
|
|
|
data, err := os.ReadFile(path)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to read SQLite file: %s", err.Error())
|
|
|
|
}
|
|
|
|
if IsWALModeEnabled(data) {
|
|
|
|
t.Fatalf("non WAL data marked as WAL")
|
|
|
|
}
|
|
|
|
if !IsDELETEModeEnabled(data) {
|
|
|
|
t.Fatalf("data marked as non-DELETE")
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
func Test_IsWALModeEnabledOnDiskWAL(t *testing.T) {
|
|
|
|
path := mustTempFile()
|
|
|
|
defer os.Remove(path)
|
|
|
|
|
|
|
|
dsn := fmt.Sprintf("file:%s", path)
|
|
|
|
db, err := sql.Open("sqlite3", dsn)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to create SQLite database: %s", err.Error())
|
|
|
|
}
|
|
|
|
_, err = db.Exec("CREATE TABLE foo (name TEXT)")
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to create table: %s", err.Error())
|
|
|
|
}
|
|
|
|
_, err = db.Exec("PRAGMA journal_mode=WAL")
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to enable WAL mode: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
_, err = db.Exec(`INSERT INTO foo(name) VALUES("fiona")`)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("error inserting record into table: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
if !IsValidSQLiteWALFile(path + "-wal") {
|
|
|
|
t.Fatalf("WAL file marked not marked as valid")
|
|
|
|
}
|
|
|
|
|
|
|
|
if err := db.Close(); err != nil {
|
|
|
|
t.Fatalf("failed to close database: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
if !IsWALModeEnabledSQLiteFile(path) {
|
|
|
|
t.Fatalf("WAL file marked as non-WAL")
|
|
|
|
}
|
|
|
|
if IsDELETEModeEnabledSQLiteFile(path) {
|
|
|
|
t.Fatalf("WAL file marked as DELETE")
|
|
|
|
}
|
|
|
|
|
|
|
|
data, err := os.ReadFile(path)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to read SQLite file: %s", err.Error())
|
|
|
|
}
|
|
|
|
if !IsWALModeEnabled(data) {
|
|
|
|
t.Fatalf("WAL data marked as non-WAL")
|
|
|
|
}
|
|
|
|
if IsDELETEModeEnabled(data) {
|
|
|
|
t.Fatalf("WAL data marked as DELETE")
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// Test_WALDatabaseCreatedOK tests that a WAL file is created, and that
|
|
|
|
// a checkpoint succeeds
|
|
|
|
func Test_WALDatabaseCreatedOK(t *testing.T) {
|
|
|
|
path := mustTempFile()
|
|
|
|
defer os.Remove(path)
|
|
|
|
|
|
|
|
db, err := Open(path, false, true)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to open database in WAL mode: %s", err.Error())
|
|
|
|
}
|
|
|
|
defer db.Close()
|
|
|
|
|
|
|
|
if !db.WALEnabled() {
|
|
|
|
t.Fatalf("WAL mode not enabled")
|
|
|
|
}
|
|
|
|
|
|
|
|
if db.InMemory() {
|
|
|
|
t.Fatalf("on-disk WAL database marked as in-memory")
|
|
|
|
}
|
|
|
|
|
|
|
|
if _, err := db.ExecuteStringStmt("CREATE TABLE foo (id INTEGER NOT NULL PRIMARY KEY, name TEXT)"); err != nil {
|
|
|
|
t.Fatalf("failed to create table: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
if !IsWALModeEnabledSQLiteFile(path) {
|
|
|
|
t.Fatalf("SQLite file not marked as WAL")
|
|
|
|
}
|
|
|
|
|
|
|
|
walPath := path + "-wal"
|
|
|
|
if _, err := os.Stat(walPath); os.IsNotExist(err) {
|
|
|
|
t.Fatalf("WAL file does not exist")
|
|
|
|
}
|
|
|
|
|
|
|
|
if err := db.Checkpoint(5 * time.Second); err != nil {
|
|
|
|
t.Fatalf("failed to checkpoint database in WAL mode: %s", err.Error())
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// Test_WALDatabaseCreatedOKFromDELETE tests that a WAL database is created properly,
|
|
|
|
// even when supplied with a DELETE-mode database.
|
|
|
|
func Test_WALDatabaseCreatedOKFromDELETE(t *testing.T) {
|
|
|
|
deletePath := mustTempFile()
|
|
|
|
defer os.Remove(deletePath)
|
|
|
|
deleteDB, err := Open(deletePath, false, false)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to open database in WAL mode: %s", err.Error())
|
|
|
|
}
|
|
|
|
defer deleteDB.Close()
|
|
|
|
if _, err := deleteDB.ExecuteStringStmt("CREATE TABLE foo (id INTEGER NOT NULL PRIMARY KEY, name TEXT)"); err != nil {
|
|
|
|
t.Fatalf("failed to create table: %s", err.Error())
|
|
|
|
}
|
|
|
|
_, err = deleteDB.ExecuteStringStmt(`INSERT INTO foo(name) VALUES("fiona")`)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("error executing insertion into table: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
walDB, err := Open(deletePath, false, true)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to open database in WAL mode: %s", err.Error())
|
|
|
|
}
|
|
|
|
defer walDB.Close()
|
|
|
|
if !IsWALModeEnabledSQLiteFile(deletePath) {
|
|
|
|
t.Fatalf("SQLite file not marked as WAL")
|
|
|
|
}
|
|
|
|
rows, err := walDB.QueryStringStmt("SELECT * FROM foo")
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to query WAL table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if exp, got := `[{"columns":["id","name"],"types":["integer","text"],"values":[[1,"fiona"]]}]`, asJSON(rows); exp != got {
|
|
|
|
t.Fatalf("unexpected results for query, expected %s, got %s", exp, got)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// Test_DELETEDatabaseCreatedOKFromWAL tests that a DELETE database is created properly,
|
|
|
|
// even when supplied with a WAL-mode database.
|
|
|
|
func Test_DELETEDatabaseCreatedOKFromWAL(t *testing.T) {
|
|
|
|
walPath := mustTempFile()
|
|
|
|
defer os.Remove(walPath)
|
|
|
|
walDB, err := Open(walPath, false, true)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to open database in WAL mode: %s", err.Error())
|
|
|
|
}
|
|
|
|
defer walDB.Close()
|
|
|
|
if _, err := walDB.ExecuteStringStmt("CREATE TABLE foo (id INTEGER NOT NULL PRIMARY KEY, name TEXT)"); err != nil {
|
|
|
|
t.Fatalf("failed to create table: %s", err.Error())
|
|
|
|
}
|
|
|
|
_, err = walDB.ExecuteStringStmt(`INSERT INTO foo(name) VALUES("fiona")`)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("error executing insertion into table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if err := walDB.Close(); err != nil {
|
|
|
|
// Closing the WAL database is required if it's to be opened in DELETE mode.
|
|
|
|
t.Fatalf("failed to close database: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
deleteDB, err2 := Open(walPath, false, false)
|
|
|
|
if err2 != nil {
|
|
|
|
t.Fatalf("failed to open database in DELETE mode: %s", err2.Error())
|
|
|
|
}
|
|
|
|
defer deleteDB.Close()
|
|
|
|
if !IsDELETEModeEnabledSQLiteFile(walPath) {
|
|
|
|
t.Fatalf("SQLite file not marked as WAL")
|
|
|
|
}
|
|
|
|
rows, err := deleteDB.QueryStringStmt("SELECT * FROM foo")
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to query WAL table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if exp, got := `[{"columns":["id","name"],"types":["integer","text"],"values":[[1,"fiona"]]}]`, asJSON(rows); exp != got {
|
|
|
|
t.Fatalf("unexpected results for query, expected %s, got %s", exp, got)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// Test_WALReplayOK tests that WAL files are replayed as expected.
|
|
|
|
func Test_WALReplayOK(t *testing.T) {
|
|
|
|
testFunc := func(t *testing.T, replayIntoDelete bool) {
|
|
|
|
dbPath := mustTempFile()
|
|
|
|
defer os.Remove(dbPath)
|
|
|
|
db, err := Open(dbPath, false, true)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to open database in WAL mode: %s", err.Error())
|
|
|
|
}
|
|
|
|
defer db.Close()
|
|
|
|
|
|
|
|
dbFile := filepath.Base(dbPath)
|
|
|
|
walPath := dbPath + "-wal"
|
|
|
|
walFile := filepath.Base(walPath)
|
|
|
|
|
|
|
|
replayDir := mustTempDir()
|
|
|
|
defer os.RemoveAll(replayDir)
|
|
|
|
replayDBPath := filepath.Join(replayDir, dbFile)
|
|
|
|
|
|
|
|
// Take over control of checkpointing
|
|
|
|
if err := db.DisableCheckpointing(); err != nil {
|
|
|
|
t.Fatalf("failed to disable checkpointing: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
// Copy the SQLite file and WAL #1
|
|
|
|
if _, err := db.ExecuteStringStmt("CREATE TABLE foo (id INTEGER NOT NULL PRIMARY KEY, name TEXT)"); err != nil {
|
|
|
|
t.Fatalf("failed to create table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if !fileExists(walPath) {
|
|
|
|
t.Fatalf("WAL file at %s does not exist", walPath)
|
|
|
|
}
|
|
|
|
mustCopyFile(replayDBPath, dbPath)
|
|
|
|
mustCopyFile(filepath.Join(replayDir, walFile+"_001"), walPath)
|
|
|
|
if err := db.Checkpoint(5 * time.Second); err != nil {
|
|
|
|
t.Fatalf("failed to checkpoint database in WAL mode: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
// Copy WAL #2
|
|
|
|
_, err = db.ExecuteStringStmt(`INSERT INTO foo(name) VALUES("fiona")`)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("error executing insertion into table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if !fileExists(walPath) {
|
|
|
|
t.Fatalf("WAL file at %s does not exist", walPath)
|
|
|
|
}
|
|
|
|
mustCopyFile(filepath.Join(replayDir, walFile+"_002"), walPath)
|
|
|
|
if err := db.Checkpoint(5 * time.Second); err != nil {
|
|
|
|
t.Fatalf("failed to checkpoint database in WAL mode: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
// Copy WAL #3
|
|
|
|
_, err = db.ExecuteStringStmt(`INSERT INTO foo(name) VALUES("declan")`)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("error executing insertion into table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if !fileExists(walPath) {
|
|
|
|
t.Fatalf("WAL file at %s does not exist", walPath)
|
|
|
|
}
|
|
|
|
mustCopyFile(filepath.Join(replayDir, walFile+"_003"), walPath)
|
|
|
|
|
|
|
|
if err := db.Close(); err != nil {
|
|
|
|
t.Fatalf("failed to close database: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
wals := []string{
|
|
|
|
filepath.Join(replayDir, walFile+"_001"),
|
|
|
|
filepath.Join(replayDir, walFile+"_002"),
|
|
|
|
filepath.Join(replayDir, walFile+"_003"),
|
|
|
|
}
|
|
|
|
if err := ReplayWAL(replayDBPath, wals, replayIntoDelete); err != nil {
|
|
|
|
t.Fatalf("failed to replay WAL files: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
if replayIntoDelete {
|
|
|
|
if !IsDELETEModeEnabledSQLiteFile(replayDBPath) {
|
|
|
|
t.Fatal("replayed database not marked as DELETE mode")
|
|
|
|
}
|
|
|
|
} else {
|
|
|
|
if !IsWALModeEnabledSQLiteFile(replayDBPath) {
|
|
|
|
t.Fatal("replayed database not marked as WAL mode")
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// Check that there are no files ending in -wal in the replay directory
|
|
|
|
walFiles, err := filepath.Glob(filepath.Join(replayDir, "*-wal"))
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to glob replay directory: %s", err.Error())
|
|
|
|
}
|
|
|
|
if len(walFiles) != 0 {
|
|
|
|
t.Fatalf("replay directory contains WAL files: %s", walFiles)
|
|
|
|
}
|
|
|
|
|
|
|
|
replayedDB, err := Open(replayDBPath, false, true)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to open replayed database: %s", err.Error())
|
|
|
|
}
|
|
|
|
rows, err := replayedDB.QueryStringStmt("SELECT * FROM foo")
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to query WAL table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if exp, got := `[{"columns":["id","name"],"types":["integer","text"],"values":[[1,"fiona"],[2,"declan"]]}]`, asJSON(rows); exp != got {
|
|
|
|
t.Fatalf("unexpected results for query, expected %s, got %s", exp, got)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
t.Run("replayIntoWAL", func(t *testing.T) {
|
|
|
|
testFunc(t, false)
|
|
|
|
})
|
|
|
|
t.Run("replayIntoDELETE", func(t *testing.T) {
|
|
|
|
testFunc(t, true)
|
|
|
|
})
|
|
|
|
}
|
|
|
|
|
|
|
|
func Test_WALReplayFailures(t *testing.T) {
|
|
|
|
dbDir := mustTempDir()
|
|
|
|
defer os.RemoveAll(dbDir)
|
|
|
|
walDir := mustTempDir()
|
|
|
|
defer os.RemoveAll(walDir)
|
|
|
|
|
|
|
|
err := ReplayWAL(filepath.Join(dbDir, "foo.db"), []string{filepath.Join(walDir, "foo.db-wal")}, false)
|
|
|
|
if err != ErrWALReplayDirectoryMismatch {
|
|
|
|
t.Fatalf("expected %s, got %s", ErrWALReplayDirectoryMismatch, err.Error())
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
func test_FileCreationOnDisk(t *testing.T, db *DB) {
|
|
|
|
defer db.Close()
|
|
|
|
if db.InMemory() {
|
|
|
|
t.Fatal("on-disk database marked as in-memory")
|
|
|
|
}
|
|
|
|
if db.FKEnabled() {
|
|
|
|
t.Fatal("FK constraints marked as enabled")
|
|
|
|
}
|
|
|
|
|
|
|
|
// Confirm checkpoint works on all types of on-disk databases. Worst case, this
|
|
|
|
// should be ignored.
|
|
|
|
if err := db.Checkpoint(5 * time.Second); err != nil {
|
|
|
|
t.Fatalf("failed to checkpoint database in DELETE mode: %s", err.Error())
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// test_ConnectionIsolationOnDisk test that ISOLATION behavior of on-disk databases doesn't
|
|
|
|
// change unexpectedly.
|
|
|
|
func test_ConnectionIsolationOnDisk(t *testing.T, db *DB) {
|
|
|
|
r, err := db.ExecuteStringStmt("CREATE TABLE foo (id INTEGER NOT NULL PRIMARY KEY, name TEXT)")
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to create table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if exp, got := `[{}]`, asJSON(r); exp != got {
|
|
|
|
t.Fatalf("unexpected results for query, expected %s, got %s", exp, got)
|
|
|
|
}
|
|
|
|
|
|
|
|
r, err = db.ExecuteStringStmt("BEGIN")
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to create table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if exp, got := `[{}]`, asJSON(r); exp != got {
|
|
|
|
t.Fatalf("unexpected results for query, expected %s, got %s", exp, got)
|
|
|
|
}
|
|
|
|
|
|
|
|
r, err = db.ExecuteStringStmt(`INSERT INTO foo(name) VALUES("fiona")`)
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("error executing insertion into table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if exp, got := `[{"last_insert_id":1,"rows_affected":1}]`, asJSON(r); exp != got {
|
|
|
|
t.Fatalf("unexpected results for execute, expected %s, got %s", exp, got)
|
|
|
|
}
|
|
|
|
|
|
|
|
q, err := db.QueryStringStmt("SELECT * FROM foo")
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to query empty table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if exp, got := `[{"columns":["id","name"],"types":["integer","text"]}]`, asJSON(q); exp != got {
|
|
|
|
t.Fatalf("unexpected results for query, expected %s, got %s", exp, got)
|
|
|
|
}
|
|
|
|
|
|
|
|
_, err = db.ExecuteStringStmt("COMMIT")
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("error executing insertion into table: %s", err.Error())
|
|
|
|
}
|
|
|
|
|
|
|
|
q, err = db.QueryStringStmt("SELECT * FROM foo")
|
|
|
|
if err != nil {
|
|
|
|
t.Fatalf("failed to query empty table: %s", err.Error())
|
|
|
|
}
|
|
|
|
if exp, got := `[{"columns":["id","name"],"types":["integer","text"],"values":[[1,"fiona"]]}]`, asJSON(q); exp != got {
|
|
|
|
t.Fatalf("unexpected results for query, expected %s, got %s", exp, got)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
func Test_DatabaseCommonOnDiskOperations(t *testing.T) {
|
|
|
|
testCases := []struct {
|
|
|
|
name string
|
|
|
|
testFunc func(*testing.T, *DB)
|
|
|
|
}{
|
|
|
|
{"FileCreationOnDisk", test_FileCreationOnDisk},
|
|
|
|
{"ConnectionIsolationOnDisk", test_ConnectionIsolationOnDisk},
|
|
|
|
}
|
|
|
|
|
|
|
|
for _, tc := range testCases {
|
|
|
|
db, path := mustCreateOnDiskDatabase()
|
|
|
|
defer db.Close()
|
|
|
|
defer os.Remove(path)
|
|
|
|
t.Run(tc.name+":disk", func(t *testing.T) {
|
|
|
|
tc.testFunc(t, db)
|
|
|
|
})
|
|
|
|
|
|
|
|
db, path = mustCreateOnDiskDatabaseWAL()
|
|
|
|
defer db.Close()
|
|
|
|
defer os.Remove(path)
|
|
|
|
t.Run(tc.name+":wal", func(t *testing.T) {
|
|
|
|
tc.testFunc(t, db)
|
|
|
|
})
|
|
|
|
}
|
|
|
|
}
|