cloudflare/cloudflared
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dbconnect/sql.go
318lines · modeblame
759cd019Ashcon Partovi6 years ago | 1 | package dbconnect |
| 2 | | |
| 3 | import ( | |
| 4 | "context" | |
| 5 | "database/sql" | |
| 6 | "encoding/json" | |
| 7 | "fmt" | |
| 8 | "net/url" | |
| 9 | "reflect" | |
| 10 | "strings" | |
| 11 | | |
| 12 | "github.com/jmoiron/sqlx" | |
| 13 | "github.com/pkg/errors" | |
| 14 | "github.com/xo/dburl" | |
| 15 | | |
| 16 | // SQL drivers self-register with the database/sql package. | |
| 17 | // https://github.com/golang/go/wiki/SQLDrivers | |
| 18 | _ "github.com/denisenkom/go-mssqldb" | |
| 19 | _ "github.com/go-sql-driver/mysql" | |
| 20 | _ "github.com/mattn/go-sqlite3" | |
| 21 | | |
| 22 | "github.com/kshvakov/clickhouse" | |
| 23 | "github.com/lib/pq" | |
| 24 | ) | |
| 25 | | |
| 26 | // SQLClient is a Client that talks to a SQL database. | |
| 27 | type SQLClient struct { | |
| 28 | Dialect string | |
| 29 | driver *sqlx.DB | |
| 30 | } | |
| 31 | | |
| 32 | // NewSQLClient creates a SQL client based on its URL scheme. | |
| 33 | func NewSQLClient(ctx context.Context, originURL *url.URL) (Client, error) { | |
| 34 | res, err := dburl.Parse(originURL.String()) | |
| 35 | if err != nil { | |
| 36 | helpText := fmt.Sprintf("supported drivers: %+q, see documentation for more details: %s", sql.Drivers(), "https://godoc.org/github.com/xo/dburl") | |
| 37 | return nil, fmt.Errorf("could not parse sql database url '%s': %s\n%s", originURL, err.Error(), helpText) | |
| 38 | } | |
| 39 | | |
| 40 | // Establishes the driver, but does not test the connection. | |
| 41 | driver, err := sqlx.Open(res.Driver, res.DSN) | |
| 42 | if err != nil { | |
| 43 | return nil, fmt.Errorf("could not open sql driver %s: %s\n%s", res.Driver, err.Error(), res.DSN) | |
| 44 | } | |
| 45 | | |
| 46 | // Closes the driver, will occur when the context finishes. | |
| 47 | go func() { | |
| 48 | <-ctx.Done() | |
| 49 | driver.Close() | |
| 50 | }() | |
| 51 | | |
| 52 | return &SQLClient{driver.DriverName(), driver}, nil | |
| 53 | } | |
| 54 | | |
| 55 | // Ping verifies a connection to the database is still alive. | |
| 56 | func (client *SQLClient) Ping(ctx context.Context) error { | |
| 57 | return client.driver.PingContext(ctx) | |
| 58 | } | |
| 59 | | |
| 60 | // Submit queries or executes a command to the SQL database. | |
| 61 | func (client *SQLClient) Submit(ctx context.Context, cmd *Command) (interface{}, error) { | |
| 62 | txx, err := cmd.ValidateSQL(client.Dialect) | |
| 63 | if err != nil { | |
| 64 | return nil, err | |
| 65 | } | |
| 66 | | |
| 67 | ctx, cancel := context.WithTimeout(ctx, cmd.Timeout) | |
| 68 | defer cancel() | |
| 69 | | |
| 70 | var res interface{} | |
| 71 | | |
| 72 | // Get the next available sql.Conn and submit the Command. | |
| 73 | err = sqlConn(ctx, client.driver, txx, func(conn *sql.Conn) error { | |
| 74 | stmt := cmd.Statement | |
| 75 | args := cmd.Arguments.Positional | |
| 76 | | |
| 77 | if cmd.Mode == "query" { | |
| 78 | res, err = sqlQuery(ctx, conn, stmt, args) | |
| 79 | } else { | |
| 80 | res, err = sqlExec(ctx, conn, stmt, args) | |
| 81 | } | |
| 82 | | |
| 83 | return err | |
| 84 | }) | |
| 85 | | |
| 86 | return res, err | |
| 87 | } | |
| 88 | | |
| 89 | // ValidateSQL extends the contract of Command for SQL dialects: | |
| 90 | // mode is conformed, arguments are []sql.NamedArg, and isolation is a sql.IsolationLevel. | |
| 91 | // | |
| 92 | // When the command should not be wrapped in a transaction, *sql.TxOptions and error will both be nil. | |
| 93 | func (cmd *Command) ValidateSQL(dialect string) (*sql.TxOptions, error) { | |
| 94 | err := cmd.Validate() | |
| 95 | if err != nil { | |
| 96 | return nil, err | |
| 97 | } | |
| 98 | | |
| 99 | mode, err := sqlMode(cmd.Mode) | |
| 100 | if err != nil { | |
| 101 | return nil, err | |
| 102 | } | |
| 103 | | |
| 104 | // Mutates Arguments to only use positional arguments with the type sql.NamedArg. | |
| 105 | // This is a required by the sql.Driver before submitting arguments. | |
| 106 | cmd.Arguments.sql(dialect) | |
| 107 | | |
| 108 | iso, err := sqlIsolation(cmd.Isolation) | |
| 109 | if err != nil { | |
| 110 | return nil, err | |
| 111 | } | |
| 112 | | |
| 113 | // When isolation is out-of-range, this is indicative that no | |
| 114 | // transaction should be executed and sql.TxOptions should be nil. | |
| 115 | if iso < sql.LevelDefault { | |
| 116 | return nil, nil | |
| 117 | } | |
| 118 | | |
| 119 | // In query mode, execute the transaction in read-only, unless it's Microsoft SQL | |
| 120 | // which does not support that type of transaction. | |
| 121 | readOnly := mode == "query" && dialect != "mssql" | |
| 122 | | |
| 123 | return &sql.TxOptions{Isolation: iso, ReadOnly: readOnly}, nil | |
| 124 | } | |
| 125 | | |
| 126 | // sqlConn gets the next available sql.Conn in the connection pool and runs a function to use it. | |
| 127 | // | |
| 128 | // If the transaction options are nil, run the useIt function outside a transaction. | |
| 129 | // This is potentially an unsafe operation if the command does not clean up its state. | |
| 130 | func sqlConn(ctx context.Context, driver *sqlx.DB, txx *sql.TxOptions, useIt func(*sql.Conn) error) error { | |
| 131 | conn, err := driver.Conn(ctx) | |
| 132 | if err != nil { | |
| 133 | return err | |
| 134 | } | |
| 135 | defer conn.Close() | |
| 136 | | |
| 137 | // If transaction options are specified, begin and defer a rollback to catch errors. | |
| 138 | var tx *sql.Tx | |
| 139 | if txx != nil { | |
| 140 | tx, err = conn.BeginTx(ctx, txx) | |
| 141 | if err != nil { | |
| 142 | return err | |
| 143 | } | |
| 144 | defer tx.Rollback() | |
| 145 | } | |
| 146 | | |
| 147 | err = useIt(conn) | |
| 148 | | |
| 149 | // Check if useIt was successful and a transaction exists before committing. | |
| 150 | if err == nil && tx != nil { | |
| 151 | err = tx.Commit() | |
| 152 | } | |
| 153 | | |
| 154 | return err | |
| 155 | } | |
| 156 | | |
| 157 | // sqlQuery queries rows on a sql.Conn and returns an array of result objects. | |
| 158 | func sqlQuery(ctx context.Context, conn *sql.Conn, stmt string, args []interface{}) ([]map[string]interface{}, error) { | |
| 159 | rows, err := conn.QueryContext(ctx, stmt, args...) | |
| 160 | if err == nil { | |
| 161 | return sqlRows(rows) | |
| 162 | } | |
| 163 | return nil, err | |
| 164 | } | |
| 165 | | |
| 166 | // sqlExec executes a command on a sql.Conn and returns the result of the operation. | |
| 167 | func sqlExec(ctx context.Context, conn *sql.Conn, stmt string, args []interface{}) (sqlResult, error) { | |
| 168 | exec, err := conn.ExecContext(ctx, stmt, args...) | |
| 169 | if err == nil { | |
| 170 | return sqlResultFrom(exec), nil | |
| 171 | } | |
| 172 | return sqlResult{}, err | |
| 173 | } | |
| 174 | | |
| 175 | // sql mutates Arguments to contain a positional []sql.NamedArg. | |
| 176 | // | |
| 177 | // The actual return type is []interface{} due to the native Golang | |
| 178 | // function signatures for sql.Exec and sql.Query being generic. | |
| 179 | func (args *Arguments) sql(dialect string) { | |
| 180 | result := args.Positional | |
| 181 | | |
| 182 | for i, val := range result { | |
| 183 | result[i] = sqlArg("", val, dialect) | |
| 184 | } | |
| 185 | | |
| 186 | for key, val := range args.Named { | |
| 187 | result = append(result, sqlArg(key, val, dialect)) | |
| 188 | } | |
| 189 | | |
| 190 | args.Positional = result | |
| 191 | args.Named = map[string]interface{}{} | |
| 192 | } | |
| 193 | | |
| 194 | // sqlArg creates a sql.NamedArg from a key-value pair and an optional dialect. | |
| 195 | // | |
| 196 | // Certain dialects will need to wrap objects, such as arrays, to conform its driver requirements. | |
| 197 | func sqlArg(key, val interface{}, dialect string) sql.NamedArg { | |
| 198 | switch reflect.ValueOf(val).Kind() { | |
| 199 | | |
| 200 | // PostgreSQL and Clickhouse require arrays to be wrapped before | |
| 201 | // being inserted into the driver interface. | |
| 202 | case reflect.Slice, reflect.Array: | |
| 203 | switch dialect { | |
| 204 | case "postgres": | |
| 205 | val = pq.Array(val) | |
| 206 | case "clickhouse": | |
| 207 | val = clickhouse.Array(val) | |
| 208 | } | |
| 209 | } | |
| 210 | | |
| 211 | return sql.Named(fmt.Sprint(key), val) | |
| 212 | } | |
| 213 | | |
| 214 | // sqlIsolation tries to match a string to a sql.IsolationLevel. | |
| 215 | func sqlIsolation(str string) (sql.IsolationLevel, error) { | |
| 216 | if str == "none" { | |
| 217 | return sql.IsolationLevel(-1), nil | |
| 218 | } | |
| 219 | | |
| 220 | for iso := sql.LevelDefault; ; iso++ { | |
| 221 | if iso > sql.LevelLinearizable { | |
| 222 | return -1, fmt.Errorf("cannot provide an invalid sql isolation level: '%s'", str) | |
| 223 | } | |
| 224 | | |
| 225 | if str == "" || strings.EqualFold(iso.String(), strings.ReplaceAll(str, "_", " ")) { | |
| 226 | return iso, nil | |
| 227 | } | |
| 228 | } | |
| 229 | } | |
| 230 | | |
| 231 | // sqlMode tries to match a string to a command mode: 'query' or 'exec' for now. | |
| 232 | func sqlMode(str string) (string, error) { | |
| 233 | switch str { | |
| 234 | case "query", "exec": | |
| 235 | return str, nil | |
| 236 | default: | |
| 237 | return "", fmt.Errorf("cannot provide invalid sql mode: '%s'", str) | |
| 238 | } | |
| 239 | } | |
| 240 | | |
| 241 | // sqlRows scans through a SQL result set and returns an array of objects. | |
| 242 | func sqlRows(rows *sql.Rows) ([]map[string]interface{}, error) { | |
| 243 | columns, err := rows.Columns() | |
| 244 | if err != nil { | |
| 245 | return nil, errors.Wrap(err, "could not extract columns from result") | |
| 246 | } | |
| 247 | defer rows.Close() | |
| 248 | | |
| 249 | types, err := rows.ColumnTypes() | |
| 250 | if err != nil { | |
| 251 | // Some drivers do not support type extraction, so fail silently and continue. | |
| 252 | types = make([]*sql.ColumnType, len(columns)) | |
| 253 | } | |
| 254 | | |
| 255 | values := make([]interface{}, len(columns)) | |
| 256 | pointers := make([]interface{}, len(columns)) | |
| 257 | | |
| 258 | var results []map[string]interface{} | |
| 259 | for rows.Next() { | |
| 260 | for i := range columns { | |
| 261 | pointers[i] = &values[i] | |
| 262 | } | |
| 263 | rows.Scan(pointers...) | |
| 264 | | |
| 265 | // Convert a row, an array of values, into an object where | |
| 266 | // each key is the name of its respective column. | |
| 267 | entry := make(map[string]interface{}) | |
| 268 | for i, col := range columns { | |
| 269 | entry[col] = sqlValue(values[i], types[i]) | |
| 270 | } | |
| 271 | results = append(results, entry) | |
| 272 | } | |
| 273 | | |
| 274 | return results, nil | |
| 275 | } | |
| 276 | | |
| 277 | // sqlValue handles special cases where sql.Rows does not return a "human-readable" object. | |
| 278 | func sqlValue(val interface{}, col *sql.ColumnType) interface{} { | |
| 279 | bytes, ok := val.([]byte) | |
| 280 | if ok { | |
| 281 | // Opportunistically check for embeded JSON and convert it to a first-class object. | |
| 282 | var embeded interface{} | |
| 283 | if json.Unmarshal(bytes, &embeded) == nil { | |
| 284 | return embeded | |
| 285 | } | |
| 286 | | |
| 287 | // STOR-604: investigate a way to coerce PostgreSQL arrays '{a, b, ...}' into JSON. | |
| 288 | // Although easy with strings, it becomes more difficult with special types like INET[]. | |
| 289 | | |
| 290 | return string(bytes) | |
| 291 | } | |
| 292 | | |
| 293 | return val | |
| 294 | } | |
| 295 | | |
| 296 | // sqlResult is a thin wrapper around sql.Result. | |
| 297 | type sqlResult struct { | |
| 298 | LastInsertId int64 `json:"last_insert_id"` | |
| 299 | RowsAffected int64 `json:"rows_affected"` | |
| 300 | } | |
| 301 | | |
| 302 | // sqlResultFrom converts sql.Result into a JSON-marshable sqlResult. | |
| 303 | func sqlResultFrom(res sql.Result) sqlResult { | |
| 304 | insertID, errID := res.LastInsertId() | |
| 305 | rowsAffected, errRows := res.RowsAffected() | |
| 306 | | |
| 307 | // If an error occurs when extracting the result, it is because the | |
| 308 | // driver does not support that specific field. Instead of passing this | |
| 309 | // to the user, omit the field in the response. | |
| 310 | if errID != nil { | |
| 311 | insertID = -1 | |
| 312 | } | |
| 313 | if errRows != nil { | |
| 314 | rowsAffected = -1 | |
| 315 | } | |
| 316 | | |
| 317 | return sqlResult{insertID, rowsAffected} | |
| 318 | } |