b54f8a1b97
This commit adds the ExtendedBackend interface which is an extension to the walletdb.DB interface. This paves the way to using etcd.db.View and etcd.db.Update in the global View and Update functions without much code rewrite.
125 lines
4.9 KiB
Go
125 lines
4.9 KiB
Go
package kvdb
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import (
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"github.com/btcsuite/btcwallet/walletdb"
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_ "github.com/btcsuite/btcwallet/walletdb/bdb" // Import to register backend.
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)
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// Update opens a database read/write transaction and executes the function f
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// with the transaction passed as a parameter. After f exits, if f did not
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// error, the transaction is committed. Otherwise, if f did error, the
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// transaction is rolled back. If the rollback fails, the original error
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// returned by f is still returned. If the commit fails, the commit error is
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// returned.
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func Update(db Backend, f func(tx RwTx) error) error {
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if extendedDB, ok := db.(ExtendedBackend); ok {
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return extendedDB.Update(f)
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}
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return walletdb.Update(db, f)
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}
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// View opens a database read transaction and executes the function f with the
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// transaction passed as a parameter. After f exits, the transaction is rolled
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// back. If f errors, its error is returned, not a rollback error (if any
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// occur).
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func View(db Backend, f func(tx ReadTx) error) error {
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if extendedDB, ok := db.(ExtendedBackend); ok {
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return extendedDB.View(f)
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}
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return walletdb.View(db, f)
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}
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// Batch is identical to the Update call, but it attempts to combine several
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// individual Update transactions into a single write database transaction on
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// an optimistic basis. This only has benefits if multiple goroutines call
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// Batch.
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var Batch = walletdb.Batch
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// Create initializes and opens a database for the specified type. The
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// arguments are specific to the database type driver. See the documentation
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// for the database driver for further details.
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//
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// ErrDbUnknownType will be returned if the database type is not registered.
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var Create = walletdb.Create
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// Backend represents an ACID database. All database access is performed
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// through read or read+write transactions.
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type Backend = walletdb.DB
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// ExtendedBackend is and interface that supports View and Update and also able
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// to collect database access patterns.
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type ExtendedBackend interface {
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Backend
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// PrintStats returns all collected stats pretty printed into a string.
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PrintStats() string
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// View opens a database read transaction and executes the function f with
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// the transaction passed as a parameter. After f exits, the transaction is
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// rolled back. If f errors, its error is returned, not a rollback error
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// (if any occur).
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View(f func(tx walletdb.ReadTx) error) error
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// Update opens a database read/write transaction and executes the function
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// f with the transaction passed as a parameter. After f exits, if f did not
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// error, the transaction is committed. Otherwise, if f did error, the
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// transaction is rolled back. If the rollback fails, the original error
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// returned by f is still returned. If the commit fails, the commit error is
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// returned.
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Update(f func(tx walletdb.ReadWriteTx) error) error
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}
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// Open opens an existing database for the specified type. The arguments are
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// specific to the database type driver. See the documentation for the database
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// driver for further details.
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//
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// ErrDbUnknownType will be returned if the database type is not registered.
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var Open = walletdb.Open
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// Driver defines a structure for backend drivers to use when they registered
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// themselves as a backend which implements the Backend interface.
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type Driver = walletdb.Driver
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// ReadBucket represents a bucket (a hierarchical structure within the
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// database) that is only allowed to perform read operations.
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type ReadBucket = walletdb.ReadBucket
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// ReadCursor represents a bucket cursor that can be positioned at the start or
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// end of the bucket's key/value pairs and iterate over pairs in the bucket.
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// This type is only allowed to perform database read operations.
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type ReadCursor = walletdb.ReadCursor
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// ReadTx represents a database transaction that can only be used for reads. If
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// a database update must occur, use a RwTx.
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type ReadTx = walletdb.ReadTx
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// RwBucket represents a bucket (a hierarchical structure within the database)
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// that is allowed to perform both read and write operations.
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type RwBucket = walletdb.ReadWriteBucket
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// RwCursor represents a bucket cursor that can be positioned at the start or
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// end of the bucket's key/value pairs and iterate over pairs in the bucket.
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// This abstraction is allowed to perform both database read and write
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// operations.
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type RwCursor = walletdb.ReadWriteCursor
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// ReadWriteTx represents a database transaction that can be used for both
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// reads and writes. When only reads are necessary, consider using a ReadTx
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// instead.
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type RwTx = walletdb.ReadWriteTx
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var (
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// ErrBucketNotFound is returned when trying to access a bucket that
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// has not been created yet.
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ErrBucketNotFound = walletdb.ErrBucketNotFound
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// ErrBucketExists is returned when creating a bucket that already
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// exists.
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ErrBucketExists = walletdb.ErrBucketExists
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// ErrDatabaseNotOpen is returned when a database instance is accessed
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// before it is opened or after it is closed.
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ErrDatabaseNotOpen = walletdb.ErrDbNotOpen
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)
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