Boltdb学习笔记之三--事务与并发控制

// Tx represents a read-only or read/write transaction on the database.
// Read-only transactions can be used for retrieving values for keys and creating cursors.
// Read/write transactions can create and remove buckets and create and remove keys.
//
// IMPORTANT: You must commit or rollback transactions when you are done with
// them. Pages can not be reclaimed by the writer until no more transactions
// are using them. A long running read transaction can cause the database to
// quickly grow.
type Tx struct {
    writable       bool
    managed        bool
    db             *DB
    meta           *meta
    root           Bucket
    pages          map[pgid]*page
    stats          TxStats
    commitHandlers []func()

    // WriteFlag specifies the flag for write-related methods like WriteTo().
    // Tx opens the database file with the specified flag to copy the data.
    //
    // By default, the flag is unset, which works well for mostly in-memory
    // workloads. For databases that are much larger than available RAM,
    // set the flag to syscall.O_DIRECT to avoid trashing the page cache.
    WriteFlag int
}