From ce7698d417eb7bece3dead2d66adca6373565744 Mon Sep 17 00:00:00 2001
From: Simon Evans <si@si.org>
Date: Wed, 20 Jun 2018 14:09:50 +0100
Subject: [PATCH] NSCondition fixes: Ensure correct use of
 lock()/action/unlock() sequence

---
 Foundation/NSData.swift         | 15 +++++++++++++--
 Foundation/Process.swift        |  2 +-
 TestFoundation/TestNSLock.swift |  4 ++--
 TestFoundation/TestThread.swift |  2 +-
 4 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/Foundation/NSData.swift b/Foundation/NSData.swift
index d4eea5ac7d..993f5e0156 100644
--- a/Foundation/NSData.swift
+++ b/Foundation/NSData.swift
@@ -210,16 +210,27 @@ open class NSData : NSObject, NSCopying, NSMutableCopying, NSSecureCoding {
         } else {
             let session = URLSession(configuration: URLSessionConfiguration.default)
             let cond = NSCondition()
+            cond.lock()
+
             var resError: Error?
             var resData: Data?
+            var taskFinished = false
             let task = session.dataTask(with: url, completionHandler: { data, response, error in
+                cond.lock()
                 resData = data
                 urlResponse = response
                 resError = error
-                cond.broadcast()
+                taskFinished = true
+                cond.signal()
+                cond.unlock()
             })
+
             task.resume()
-            cond.wait()
+            while taskFinished == false {
+                cond.wait()
+            }
+            cond.unlock()
+
             guard let data = resData else {
                 throw resError!
             }
diff --git a/Foundation/Process.swift b/Foundation/Process.swift
index 47ba49b950..7139a5587c 100644
--- a/Foundation/Process.swift
+++ b/Foundation/Process.swift
@@ -242,8 +242,8 @@ open class Process: NSObject {
         
         self.processLaunchedCondition.lock()
         defer {
-            self.processLaunchedCondition.unlock()
             self.processLaunchedCondition.broadcast()
+            self.processLaunchedCondition.unlock()
         }
 
         // Dispatch the manager thread if it isn't already running
diff --git a/TestFoundation/TestNSLock.swift b/TestFoundation/TestNSLock.swift
index a86365815b..2bca129de1 100644
--- a/TestFoundation/TestNSLock.swift
+++ b/TestFoundation/TestNSLock.swift
@@ -68,15 +68,15 @@ class TestNSLock: XCTestCase {
 
         for t in 0..<threadCount {
             let thread = Thread() {
+                condition.lock()
                 arrayLock.lock()
                 threadsStarted[t] = true
                 arrayLock.unlock()
 
-                condition.lock()
                 condition.wait()
                 condition.unlock()
                 for _ in 1...50 {
-                    let r = (endSeconds * drand48()) / 50
+                    let r = Double.random(in: 0...0.02)
                     Thread.sleep(forTimeInterval: r)
                     if lock.lock(before: endTime) {
                         lock.unlock()
diff --git a/TestFoundation/TestThread.swift b/TestFoundation/TestThread.swift
index 68efcb63ec..abb907ebc0 100644
--- a/TestFoundation/TestThread.swift
+++ b/TestFoundation/TestThread.swift
@@ -45,7 +45,7 @@ class TestThread : XCTestCase {
         }
         thread.start()
 
-        let ok = condition.wait(until: Date(timeIntervalSinceNow: 10))
+        let ok = condition.wait(until: Date(timeIntervalSinceNow: 2))
         condition.unlock()
         XCTAssertTrue(ok, "NSCondition wait timed out")
     }