Documentation
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Overview ¶
AdvisoryLock implements primitives to use PostgreSQL's advisory locks.
These locks can be used to pipeline concurrent access between multiple database sessions. Keep in mind, both [Lock] and [TryLock] are stackable, can be called multiple times on the same session, requiring the same amount of calls to [Unlock] to free up the lock:
var l := NewAdvisoryLock(conn, 32) l.Lock(context.Background()) // lock does not exist previously in this session, so locks successfully l.Lock(context.Background()) // lock already exists, but this increments the lock l.Unlock() // lock is not freed yet, as it was locked twice l.Unlock() // only here lock is released See https://www.postgresql.org/docs/current/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS for more details on the specifics
of PostgreSQL advisory locks
Note: since pgxpool is used, the lock will keep a connection from the connection pool for himself; this connection is freed when the number of locked unlocks is achieved
Index ¶
- Constants
- func ColumnExists(ctx context.Context, client *db.SqlClient, tableName string, columnName string, ...) (bool, error)
- func DialectOptions() *goqu.SQLDialectOptions
- func ForeignTableExists(ctx context.Context, client *db.SqlClient, tableName string, schema string) (bool, error)
- func GetServerVersion(db *sqlx.DB, ctx context.Context) (string, error)
- func NewClient(config *ClientConfig) (*db.SqlClient, error)
- func NewMigrationManager(ctx context.Context, client *db.SqlClient, opts ...PgMigrationOption) (migrations.Manager, error)
- func TableExists(ctx context.Context, client *db.SqlClient, tableName string, schema string) (bool, error)
- func ViewExists(ctx context.Context, client *db.SqlClient, tableName string, schema string) (bool, error)
- func WithTxSession(ctx context.Context, q dbx.Querier, settings map[string]string, role string, ...) error
- type AdvisoryLock
- type ClientConfig
- type LockConn
- type PgMigrationOption
Constants ¶
const ( DefaultIdleConns = 2 DefaultMaxConns = 4 DefaultConnLifeTimeSecond = 3600 DefaultConnIdleTimeSecond = 1800 ErrEmptyDSN = utils.Error("Empty DSN") ErrNilConfig = utils.Error("Config is nil") ErrInvalidIdleConns = utils.Error("Invalid idleConns") ErrInvalidMaxConns = utils.Error("Invalid maxConns") ErrInvalidConnLifeTime = utils.Error("connLifeTime must be >= 1") ErrInvalidConnIdleTime = utils.Error("connIdleTime must be >= 1") )
const ( EngineSchema = "public" MigrationTable = "db_migration" EngineMigrationTable = EngineSchema + "." + MigrationTable MigrationLockId = 2343452349 )
const ( // ErrInvalidSettingName is returned by WithTxSession when a setting name // is not a custom (dotted) PostgreSQL configuration parameter name. ErrInvalidSettingName = utils.Error("pgsql: invalid custom setting name") // ErrInvalidRoleName is returned by WithTxSession when role cannot be // quoted as a single identifier. ErrInvalidRoleName = utils.Error("pgsql: invalid role name") // ErrNotPostgres is returned by WithTxSession when the Querier's dialect // is not PostgreSQL. ErrNotPostgres = utils.Error("pgsql: querier dialect is not PostgreSQL") )
const ( SchemaDefault = "public" TblTypeTable = "BASE TABLE" TblTypeView = "VIEW" TblTypeForeignTable = "FOREIGN TABLE" TblTypeLocal = "LOCAL TEMPORARY" )
Variables ¶
This section is empty.
Functions ¶
func ColumnExists ¶
func ColumnExists(ctx context.Context, client *db.SqlClient, tableName string, columnName string, schema string) (bool, error)
ColumnExists check if a column exists
func DialectOptions ¶
func DialectOptions() *goqu.SQLDialectOptions
func ForeignTableExists ¶
func ForeignTableExists(ctx context.Context, client *db.SqlClient, tableName string, schema string) (bool, error)
ForeignTableExists returns true if specified foreign table exists
func GetServerVersion ¶
GetServerVersion fetch postgresql version
func NewMigrationManager ¶
func NewMigrationManager(ctx context.Context, client *db.SqlClient, opts ...PgMigrationOption) (migrations.Manager, error)
func TableExists ¶
func TableExists(ctx context.Context, client *db.SqlClient, tableName string, schema string) (bool, error)
TableExists returns true if specified table exists
func ViewExists ¶
func ViewExists(ctx context.Context, client *db.SqlClient, tableName string, schema string) (bool, error)
ViewExists returns true if specified view exists
func WithTxSession ¶ added in v0.10.0
func WithTxSession(ctx context.Context, q dbx.Querier, settings map[string]string, role string, fn func(tx dbx.Querier) error) error
WithTxSession runs fn inside a transaction (via dbx.WithTx) after making settings and role transaction-local:
- each setting is applied with SELECT set_config(name, value, true), in ascending name order, with name and value as bound parameters;
- if role is not empty, SET LOCAL ROLE switches to it (the name is quoted with the Querier's gohan dialect).
Everything is undone by PostgreSQL when the transaction ends, so nothing leaks to the next user of the pooled connection. Setting names must be custom parameter names (e.g. "app.tenant_id"; see customSettingName), no two of them equal ignoring case (PostgreSQL treats them as one setting), and role must be at most 63 bytes, without a dot, and not "*"; invalid input is rejected before any statement is sent. Setting and role names should be constants: a dotted name also matches extension settings (such as auto_explain.*), which set_config changes too. If q is already a transaction, WithTxSession joins it: the settings and role then last until that outer transaction ends, not just until fn returns.
Types ¶
type AdvisoryLock ¶
type AdvisoryLock struct {
// contains filtered or unexported fields
}
func NewAdvisoryLock ¶
func (*AdvisoryLock) Close ¶
func (l *AdvisoryLock) Close()
func (*AdvisoryLock) Lock ¶
func (l *AdvisoryLock) Lock(ctx context.Context) error
Lock attempts to perform a lock, and waits until it is available
type ClientConfig ¶
type ClientConfig struct {
DSN string `json:"dsn"`
MaxOpenConns int `json:"maxOpenConns"` // MaxOpenConns max number of pool connections
MaxIdleConns int `json:"maxIdleConns"` // MaxIdleConns max number of idle pool connections
// ConnLifeTime is the duration in seconds since creation after which a connection will be automatically closed
ConnLifetime int `json:"connLifetime"`
// ConnIdleTime is the duration in seconds after which an idle connection will be automatically closed by the health check
ConnIdleTime int `json:"connIdleTime"`
}
func NewClientConfig ¶
func NewClientConfig() *ClientConfig
func (ClientConfig) Validate ¶
func (c ClientConfig) Validate() error
type PgMigrationOption ¶
type PgMigrationOption func(s *pgMigrationManager) error
func WithModule ¶
func WithModule(module string) PgMigrationOption
Source Files