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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
import Foundation
import SwiftExtensions
/// Gathers data from a stdout or stderr pipe. When it has accumulated a full line, calls the handler to handle the
/// string.
public actor PipeAsStringHandler {
/// Queue on which all data from the pipe will be handled. This allows us to have a
/// nonisolated `handle` function but ensure that data gets processed in order.
private let queue = AsyncQueue<Serial>()
private var buffer = Data()
/// The closure that actually handles
private let handler: @Sendable (String) -> Void
public init(handler: @escaping @Sendable (String) -> Void) {
self.handler = handler
}
private func handleDataFromPipeImpl(_ newData: Data) {
self.buffer += newData
while let newlineIndex = self.buffer.firstIndex(of: UInt8(ascii: "\n")) {
// Output a separate log message for every line in the pipe.
// The reason why we don't output multiple lines in a single log message is that
// a) os_log truncates log messages at about 1000 bytes. The assumption is that a single line is usually less
// than 1000 bytes long but if we merge multiple lines into one message, we might easily exceed this limit.
// b) It might be confusing why sometimes a single log message contains one line while sometimes it contains
// multiple.
handler(String(data: self.buffer[...newlineIndex], encoding: .utf8) ?? "<invalid UTF-8>")
buffer = buffer[buffer.index(after: newlineIndex)...]
}
}
public nonisolated func handleDataFromPipe(_ newData: Data) {
queue.async {
await self.handleDataFromPipeImpl(newData)
}
}
}
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