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STConcurrentDictionary.swift
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87 lines (73 loc) · 2.08 KB
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//
// STConcurrentDictionary.swift
// STBaseProject
//
// Created by 寒江孤影 on 2019/3/16.
//
import Foundation
/// 线程安全的字典容器
///
/// - 读通过 `dispatch_sync` 并发执行
/// - 写通过 `dispatch_barrier_async` 串行化
public final class STConcurrentDictionary<Key: Hashable, Value> {
private var store: [Key: Value]
private let queue = DispatchQueue(
label: "com.stbaseproject.concurrent-dictionary",
attributes: .concurrent
)
public init(_ initial: [Key: Value] = [:]) {
self.store = initial
}
public var count: Int {
queue.sync { store.count }
}
public var isEmpty: Bool {
queue.sync { store.isEmpty }
}
/// 获取当前内容快照（拷贝）
public var snapshot: [Key: Value] {
queue.sync { store }
}
public var keys: [Key] {
queue.sync { Array(store.keys) }
}
public var values: [Value] {
queue.sync { Array(store.values) }
}
public subscript(key: Key) -> Value? {
get { queue.sync { store[key] } }
set {
queue.async(flags: .barrier) {
if let newValue {
self.store[key] = newValue
} else {
self.store.removeValue(forKey: key)
}
}
}
}
public func removeValue(forKey key: Key) {
queue.async(flags: .barrier) {
self.store.removeValue(forKey: key)
}
}
public func removeAll() {
queue.async(flags: .barrier) {
self.store.removeAll()
}
}
/// 以只读方式遍历快照
public func forEach(_ body: (Key, Value) -> Void) {
let currentSnapshot = snapshot
for (key, value) in currentSnapshot {
body(key, value)
}
}
/// 原子地更新一个值：回调内对字典的修改作为整个屏障执行
/// - Parameter body: 接收可变字典
public func modify(_ body: (inout [Key: Value]) -> Void) {
queue.sync(flags: .barrier) {
body(&store)
}
}
}