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ndb: add NdbTxn transaction class

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This will be used for transactions
This commit is contained in:
William Casarin 2023-09-10 10:16:50 -07:00
parent 9398877415
commit 622a436589
2 changed files with 106 additions and 0 deletions
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4
damus.xcodeproj/project.pbxproj
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@ -156,6 +156,7 @@
4C3BEFE0281DE1ED00B3DE84 /* DamusState.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C3BEFDF281DE1ED00B3DE84 /* DamusState.swift */; };
4C3D52B6298DB4E6001C5831 /* ZapEvent.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C3D52B5298DB4E6001C5831 /* ZapEvent.swift */; };
4C3D52B8298DB5C6001C5831 /* TextEvent.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C3D52B7298DB5C6001C5831 /* TextEvent.swift */; };
4C3DCC762A9FE9EC0091E592 /* NdbTxn.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C3DCC752A9FC2030091E592 /* NdbTxn.swift */; };
4C3EA63D28FF52D600C48A62 /* bolt11.c in Sources */ = {isa = PBXBuildFile; fileRef = 4C3EA63C28FF52D600C48A62 /* bolt11.c */; };
4C3EA64128FF553900C48A62 /* hash_u5.c in Sources */ = {isa = PBXBuildFile; fileRef = 4C3EA64028FF553900C48A62 /* hash_u5.c */; };
4C3EA64428FF558100C48A62 /* sha256.c in Sources */ = {isa = PBXBuildFile; fileRef = 4C3EA64328FF558100C48A62 /* sha256.c */; };
@ -694,6 +695,7 @@
4C3BEFDF281DE1ED00B3DE84 /* DamusState.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DamusState.swift; sourceTree = "<group>"; };
4C3D52B5298DB4E6001C5831 /* ZapEvent.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ZapEvent.swift; sourceTree = "<group>"; };
4C3D52B7298DB5C6001C5831 /* TextEvent.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TextEvent.swift; sourceTree = "<group>"; };
4C3DCC752A9FC2030091E592 /* NdbTxn.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NdbTxn.swift; sourceTree = "<group>"; };
4C3EA63B28FF52D600C48A62 /* bolt11.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = bolt11.h; sourceTree = "<group>"; };
4C3EA63C28FF52D600C48A62 /* bolt11.c */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.c; path = bolt11.c; sourceTree = "<group>"; };
4C3EA63E28FF54BD00C48A62 /* short_types.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = short_types.h; sourceTree = "<group>"; };
@ -1816,6 +1818,7 @@
4CDD1ADF2A6B305F001CD4DF /* NdbTagElem.swift */,
4C478E242A9932C100489948 /* Ndb.swift */,
4CDD1AE12A6B3074001CD4DF /* NdbTagsIterator.swift */,
4C3DCC752A9FC2030091E592 /* NdbTxn.swift */,
4CE9FBB82A6B3B26007E485C /* nostrdb.c */,
4C4793032A993DB900489948 /* midl.c */,
4C4793002A993B9A00489948 /* mdb.c */,
@ -2478,6 +2481,7 @@
isa = PBXSourcesBuildPhase;
buildActionMask = 2147483647;
files = (
4C3DCC762A9FE9EC0091E592 /* NdbTxn.swift in Sources */,
4CEF958D2A9CE650000F901B /* verifier.c in Sources */,
4C32B9342A9AD01A00DC3548 /* NdbProfile.swift in Sources */,
4C32B9332A99845B00DC3548 /* Ndb.swift in Sources */,

102
nostrdb/NdbTxn.swift Normal file
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@ -0,0 +1,102 @@
//
// NdbTx.swift
// damus
//
// Created by William Casarin on 2023-08-30.
//
import Foundation
#if TXNDEBUG
fileprivate var txn_count: Int = 0
#endif
// Would use struct and ~Copyable but generics aren't supported well
class NdbTxn<T> {
var txn: ndb_txn
private var val: T!
var moved: Bool
init(ndb: Ndb, with: (NdbTxn<T>) -> T) {
self.txn = ndb_txn()
#if TXNDEBUG
txn_count += 1
print("opening transaction \(txn_count)")
#endif
let _ = ndb_begin_query(ndb.ndb.ndb, &self.txn)
self.moved = false
self.val = with(self)
}
init(txn: ndb_txn, val: T) {
self.txn = txn
self.val = val
self.moved = false
}
/// Only access temporarily! Do not store database references for longterm use. If it's a primitive type you
/// can retrieve this value with `.value`
var unsafeUnownedValue: T {
precondition(!moved)
return val
}
deinit {
if !moved {
#if TXNDEBUG
txn_count -= 1;
print("closing transaction \(txn_count)")
#endif
ndb_end_query(&self.txn)
}
}
// functor
func map<Y>(_ transform: (T) -> Y) -> NdbTxn<Y> {
self.moved = true
return .init(txn: self.txn, val: transform(val))
}
// comonad!?
// useful for moving ownership of a transaction to another value
func extend<Y>(_ with: (NdbTxn<T>) -> Y) -> NdbTxn<Y> {
self.moved = true
return .init(txn: self.txn, val: with(self))
}
}
protocol OptionalType {
associatedtype Wrapped
var optional: Wrapped? { get }
}
extension Optional: OptionalType {
typealias Wrapped = Wrapped
var optional: Wrapped? {
return self
}
}
extension NdbTxn where T: OptionalType {
func collect() -> NdbTxn<T.Wrapped>? {
guard let unwrappedVal: T.Wrapped = val.optional else {
return nil
}
self.moved = true
return NdbTxn<T.Wrapped>(txn: self.txn, val: unwrappedVal)
}
}
extension NdbTxn where T == Bool { var value: T { return self.unsafeUnownedValue } }
extension NdbTxn where T == Bool? { var value: T { return self.unsafeUnownedValue } }
extension NdbTxn where T == Int { var value: T { return self.unsafeUnownedValue } }
extension NdbTxn where T == Int? { var value: T { return self.unsafeUnownedValue } }
extension NdbTxn where T == Double { var value: T { return self.unsafeUnownedValue } }
extension NdbTxn where T == Double? { var value: T { return self.unsafeUnownedValue } }
extension NdbTxn where T == UInt64 { var value: T { return self.unsafeUnownedValue } }
extension NdbTxn where T == UInt64? { var value: T { return self.unsafeUnownedValue } }
extension NdbTxn where T == String { var value: T { return self.unsafeUnownedValue } }
extension NdbTxn where T == String? { var value: T { return self.unsafeUnownedValue } }
extension NdbTxn where T == NoteId? { var value: T { return self.unsafeUnownedValue } }
extension NdbTxn where T == NoteId { var value: T { return self.unsafeUnownedValue } }