From 9c42847ee21e3d56c46d85272348c0b61b094804 Mon Sep 17 00:00:00 2001
From: Tim Van Baak <tim.vanbaak@gmail.com>
Date: Fri, 31 Jan 2025 08:53:11 -0800
Subject: [PATCH] Add transaction DB implementation

This and the previous commit allow passing transactions to query functions
---
 core/db.go      | 35 ++++++++++++++++++++++++++++++++---
 core/db_test.go |  5 ++---
 core/env.go     |  3 +--
 core/source.go  |  4 ++--
 4 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/core/db.go b/core/db.go
index b3650b1..40d6dce 100644
--- a/core/db.go
+++ b/core/db.go
@@ -11,7 +11,8 @@ type DB interface {
 	Query(query string, args ...any) (*sql.Rows, error)
 	QueryRow(query string, args ...any) *sql.Row
 	Exec(query string, args ...any) (sql.Result, error)
-	Transact(func(*sql.Tx) error) error
+	Prepare(query string) (*sql.Stmt, error)
+	Transact(func(DB) error) error
 }
 
 type RoRwDb struct {
@@ -31,7 +32,11 @@ func (db *RoRwDb) Exec(query string, args ...any) (sql.Result, error) {
 	return db.rw.Exec(query, args...)
 }
 
-func (db *RoRwDb) Transact(transaction func(*sql.Tx) error) error {
+func (db *RoRwDb) Prepare(query string) (*sql.Stmt, error) {
+	return db.rw.Prepare(query)
+}
+
+func (db *RoRwDb) Transact(transaction func(DB) error) error {
 	tx, err := db.rw.Begin()
 	if err != nil {
 		return err
@@ -41,7 +46,7 @@ func (db *RoRwDb) Transact(transaction func(*sql.Tx) error) error {
 	if err != nil {
 		return err
 	}
-	if err = transaction(tx); err != nil {
+	if err = transaction(&TxDb{tx}); err != nil {
 		return err
 	}
 	if err = tx.Commit(); err != nil {
@@ -50,6 +55,30 @@ func (db *RoRwDb) Transact(transaction func(*sql.Tx) error) error {
 	return nil
 }
 
+type TxDb struct {
+	*sql.Tx
+}
+
+func (tx *TxDb) Query(query string, args ...any) (*sql.Rows, error) {
+	return tx.Tx.Query(query, args...)
+}
+
+func (tx *TxDb) QueryRow(query string, args ...any) *sql.Row {
+	return tx.Tx.QueryRow(query, args...)
+}
+
+func (tx *TxDb) Exec(query string, args ...any) (sql.Result, error) {
+	return tx.Tx.Exec(query, args...)
+}
+
+func (tx *TxDb) Prepare(query string) (*sql.Stmt, error) {
+	return tx.Tx.Prepare(query)
+}
+
+func (tx *TxDb) Transact(transaction func(DB) error) error {
+	return transaction(tx)
+}
+
 func defaultPragma(db *sql.DB) (sql.Result, error) {
 	return db.Exec(`
 		pragma journal_mode = WAL;
diff --git a/core/db_test.go b/core/db_test.go
index 555b8a2..93823fc 100644
--- a/core/db_test.go
+++ b/core/db_test.go
@@ -1,7 +1,6 @@
 package core
 
 import (
-	"database/sql"
 	"testing"
 
 	_ "github.com/mattn/go-sqlite3"
@@ -55,7 +54,7 @@ func TestTransaction(t *testing.T) {
 	}
 
 	// A transaction that should succeed
-	err := db.Transact(func(tx *sql.Tx) error {
+	err := db.Transact(func(tx DB) error {
 		if _, err := tx.Exec("insert into planets (name) values (?)", "mercury"); err != nil {
 			t.Fatal(err)
 		}
@@ -86,7 +85,7 @@ func TestTransaction(t *testing.T) {
 	}
 
 	// A transaction that should fail
-	err = db.Transact(func(tx *sql.Tx) error {
+	err = db.Transact(func(tx DB) error {
 		if _, err := tx.Exec("insert into planets (name) values (?)", "earth"); err != nil {
 			t.Fatal(err)
 		}
diff --git a/core/env.go b/core/env.go
index c44e109..3330daa 100644
--- a/core/env.go
+++ b/core/env.go
@@ -1,7 +1,6 @@
 package core
 
 import (
-	"database/sql"
 	"fmt"
 	"strings"
 )
@@ -28,7 +27,7 @@ func GetEnvs(db DB, source string) ([]string, error) {
 }
 
 func SetEnvs(db DB, source string, envs []string) error {
-	return db.Transact(func(tx *sql.Tx) error {
+	return db.Transact(func(tx DB) error {
 		for _, env := range envs {
 			parts := strings.SplitN(env, "=", 2)
 			if len(parts) != 2 {
diff --git a/core/source.go b/core/source.go
index 34672e1..d7a4051 100644
--- a/core/source.go
+++ b/core/source.go
@@ -49,7 +49,7 @@ func DeleteSource(db DB, name string) error {
 }
 
 func AddItems(db DB, items []Item) error {
-	return db.Transact(func(tx *sql.Tx) error {
+	return db.Transact(func(tx DB) error {
 		stmt, err := tx.Prepare(`
 			insert into items (source, id, active, title, author, body, link, time, action)
 			values (?, ?, ?, ?, ?, ?, ?, ?, jsonb(?))
@@ -96,7 +96,7 @@ func BackfillItem(new *Item, old *Item) {
 }
 
 func UpdateItems(db DB, items []Item) error {
-	return db.Transact(func(tx *sql.Tx) error {
+	return db.Transact(func(tx DB) error {
 		stmt, err := tx.Prepare(`
 			update items
 			set