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//===--------------------- SourceKitdClient.swift -------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2020 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
//
//===----------------------------------------------------------------------===//
// This file provides a wrapper of SourceKitd service.
//===----------------------------------------------------------------------===//
import sourcekitd
import Dispatch
/// An empty object to generate unique `ObjectIdentifier`s.
fileprivate class Object {}
public class SourceKitdService {
enum State {
case running
case interrupted
case semaDisabled
}
/// The queue that makes sure only one request is executed at a time
private let requestQueue = DispatchQueue(label: "SourceKitdService.requestQueue", qos: .userInitiated)
/// The queue that guards access to the `state` and `stateChangeHandlers` variables
private let stateQueue = DispatchQueue(label: "SourceKitdService.stateQueue", qos: .userInitiated)
private var state: State = .running {
didSet {
dispatchPrecondition(condition: .onQueue(stateQueue))
for handler in stateChangeHandlers.values {
handler()
}
}
}
/// Handlers to be executed whenever the `state` changes.
private var stateChangeHandlers: [ObjectIdentifier: () -> Void] = [:]
private let printRequests: Bool
public init(printRequests: Bool) {
self.printRequests = printRequests
initializeService()
}
private func sendRequestSync(_ req: SourceKitdRequest) -> sourcekitd_response_t! {
if printRequests {
print(req.description)
}
return sourcekitd_send_request_sync(req.rawRequest)
}
/// Set up a new SourceKit service instance.
private func initializeService() {
sourcekitd_initialize()
sourcekitd_set_notification_handler { [self] resp in
let response = SourceKitdResponse(resp: resp!)
stateQueue.async {
if self.state == .interrupted {
self.state = .semaDisabled
// sourcekitd came back online. Poke it to restore semantic
// functionality. Intentionally don't execute this request on the
// request queue because request order doesn't matter for this
// pseudo-document and we want it to be executed immediately, even if
// the request queue is blocked.
let request = SourceKitdRequest(uid: .request_CursorInfo)
request.addParameter(.key_SourceText, value: "")
_ = self.sendRequestSync(request)
}
if response.isConnectionInterruptionError {
self.state = .interrupted
} else if response.notificationType == .semaDisabledNotification {
self.state = .semaDisabled
} else if response.notificationType == .semaEnabledNotification {
self.state = .running
}
}
}
}
deinit {
sourcekitd_shutdown()
}
/// Crash the service. This is a workaround to set up a new service in case
/// we time out waiting for a request response and we want to handle it.
/// Replace by proper cancellation once we have cancellation support in
/// SourceKit.
public func crash() {
let request = SourceKitdRequest(uid: .request_CrashWithExit)
_ = sendRequestSync(request)
stateQueue.sync {
self.state = .interrupted
}
}
/// Execute `callback` one this service is in `desiredState`
private func waitForState(_ desiredState: State, callback: @escaping () -> Void) {
stateQueue.async { [self] in
if state == desiredState {
callback()
} else {
let identifier = ObjectIdentifier(Object())
stateChangeHandlers[identifier] = { [self] in
dispatchPrecondition(condition: .onQueue(stateQueue))
if state == desiredState {
callback()
stateChangeHandlers[identifier] = nil
}
}
}
}
}
/// Block the current thread until this service is in `desiredState`.
private func blockUntilState(_ desiredState: State) {
let semaphore = DispatchSemaphore(value: 0)
waitForState(desiredState) {
semaphore.signal()
}
semaphore.wait()
}
/// Send a request synchronously with a handler for its response.
/// - Parameter request: The request to send.
/// - Returns: The response from the sourcekitd service.
public func sendSyn(request: SourceKitdRequest) -> SourceKitdResponse {
return requestQueue.sync {
blockUntilState(.running)
return SourceKitdResponse(resp: sendRequestSync(request))
}
}
/// Send a request asynchronously with a handler for its response.
/// - Parameter request: The request to send.
/// - Parameter handler: The handler for the response in the future.
public func send(request: SourceKitdRequest,
handler: @escaping (SourceKitdResponse) -> ()) {
requestQueue.async { [self] in
blockUntilState(.running)
let response = SourceKitdResponse(resp: sendRequestSync(request))
if response.isConnectionInterruptionError {
// Set the state into the interrupted state now. We will also catch this
// in the notification handler but that has some delay and we might be
// scheduling new requests before the state is set to `interrupted`.
stateQueue.sync {
self.state = .interrupted
}
}
handler(response)
}
}
}
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