More Buffer for FileHandler Output? - swift

Question

I have the following Code:
func syncShellExec(path: String, args: [String] = []) {
let process = Process()
process.launchPath = "/bin/bash"
process.arguments = [path] + args
let outputPipe = Pipe()
let filelHandler = outputPipe.fileHandleForReading
process.standardOutput = outputPipe
process.launch()
filelHandler.readabilityHandler = { pipe in
let data = pipe.availableData
if let line = String(data: data, encoding: String.Encoding.utf8) {
DispatchQueue.main.sync {
self.output_window.string += line
self.output_window.scrollToEndOfDocument(nil)
}
} else {
print("Error decoding data: \(data.base64EncodedString())")
}
}
process.waitUntilExit()
filelHandler.readabilityHandler = nil
}
If the amount of round about 330.000 Characters is reached the output stopped immediately. Is there a way to increase the Buffer for this Operation?

Answer 1

There are two problems:
The process may terminate before all data has been read from the pipe.
Your function blocks the main thread, so that the UI eventually freezes.
Similarly as in How can I tell when a FileHandle has nothing left to be read? you should wait asynchronously for the process to terminate, and also wait for “end-of-file” on the pipe:
func asyncShellExec(path: String, args: [String] = []) {
let process = Process()
process.launchPath = "/bin/bash"
process.arguments = [path] + args
let outputPipe = Pipe()
let filelHandler = outputPipe.fileHandleForReading
process.standardOutput = outputPipe
process.launch()
let group = DispatchGroup()
group.enter()
filelHandler.readabilityHandler = { pipe in
let data = pipe.availableData
if data.isEmpty { // EOF
filelHandler.readabilityHandler = nil
group.leave()
return
}
if let line = String(data: data, encoding: String.Encoding.utf8) {
DispatchQueue.main.sync {
self.output_window.string += line
self.output_window.scrollToEndOfDocument(nil)
}
} else {
print("Error decoding data: \(data.base64EncodedString())")
}
}
process.terminationHandler = { process in
group.wait()
DispatchQueue.main.sync {
// Update UI that process has finished.
}
}
}