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Merged
rudro merged 3 commits into from
Jul 26, 2018
Merged

Add task execution package #12

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fb49490
Add task execution package
neakor Jul 26, 2018
7edc517
Remove unnecessary targets
neakor Jul 26, 2018
d9648a8
Make concurrency test more reliable
neakor Jul 26, 2018
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135 changes: 36 additions & 99 deletions Concurrency.xcodeproj/project.pbxproj
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Original file line number Diff line number Diff line change
Expand Up @@ -6,26 +6,16 @@
objectVersion = 46;
objects = {

/* Begin PBXAggregateTarget section */
"Concurrency::ConcurrencyPackageTests::ProductTarget" /* ConcurrencyPackageTests */ = {
isa = PBXAggregateTarget;
buildConfigurationList = OBJ_39 /* Build configuration list for PBXAggregateTarget "ConcurrencyPackageTests" */;
buildPhases = (
);
dependencies = (
OBJ_42 /* PBXTargetDependency */,
);
name = ConcurrencyPackageTests;
productName = ConcurrencyPackageTests;
};
/* End PBXAggregateTarget section */

/* Begin PBXBuildFile section */
41B94843210A4744007E59C8 /* SerialSequenceExecutor.swift in Sources */ = {isa = PBXBuildFile; fileRef = 41B9483F210A4744007E59C8 /* SerialSequenceExecutor.swift */; };
41B94844210A4744007E59C8 /* SequenceExecutor.swift in Sources */ = {isa = PBXBuildFile; fileRef = 41B94840210A4744007E59C8 /* SequenceExecutor.swift */; };
41B94845210A4744007E59C8 /* ConcurrentSequenceExecutor.swift in Sources */ = {isa = PBXBuildFile; fileRef = 41B94841210A4744007E59C8 /* ConcurrentSequenceExecutor.swift */; };
41B94846210A4744007E59C8 /* Task.swift in Sources */ = {isa = PBXBuildFile; fileRef = 41B94842210A4744007E59C8 /* Task.swift */; };
41B94849210A4756007E59C8 /* ConcurrentSequenceExecutorTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 41B94848210A4756007E59C8 /* ConcurrentSequenceExecutorTests.swift */; };
OBJ_27 /* AtomicBool.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_9 /* AtomicBool.swift */; };
OBJ_28 /* AtomicInt.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_10 /* AtomicInt.swift */; };
OBJ_29 /* AtomicReference.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_11 /* AtomicReference.swift */; };
OBJ_30 /* CountDownLatch.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_12 /* CountDownLatch.swift */; };
OBJ_37 /* Package.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_6 /* Package.swift */; };
OBJ_48 /* AtomicBoolTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_15 /* AtomicBoolTests.swift */; };
OBJ_49 /* AtomicIntTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_16 /* AtomicIntTests.swift */; };
OBJ_50 /* AtomicReferenceTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_17 /* AtomicReferenceTests.swift */; };
Expand All @@ -41,16 +31,14 @@
remoteGlobalIDString = "Concurrency::Concurrency";
remoteInfo = Concurrency;
};
412CDD2E20B88EAB00AF5890 /* PBXContainerItemProxy */ = {
isa = PBXContainerItemProxy;
containerPortal = OBJ_1 /* Project object */;
proxyType = 1;
remoteGlobalIDString = "Concurrency::ConcurrencyTests";
remoteInfo = ConcurrencyTests;
};
/* End PBXContainerItemProxy section */

/* Begin PBXFileReference section */
41B9483F210A4744007E59C8 /* SerialSequenceExecutor.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SerialSequenceExecutor.swift; sourceTree = "<group>"; };
41B94840210A4744007E59C8 /* SequenceExecutor.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SequenceExecutor.swift; sourceTree = "<group>"; };
41B94841210A4744007E59C8 /* ConcurrentSequenceExecutor.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ConcurrentSequenceExecutor.swift; sourceTree = "<group>"; };
41B94842210A4744007E59C8 /* Task.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Task.swift; sourceTree = "<group>"; };
41B94848210A4756007E59C8 /* ConcurrentSequenceExecutorTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ConcurrentSequenceExecutorTests.swift; sourceTree = "<group>"; };
"Concurrency::Concurrency::Product" /* Concurrency.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = Concurrency.framework; sourceTree = BUILT_PRODUCTS_DIR; };
"Concurrency::ConcurrencyTests::Product" /* ConcurrencyTests.xctest */ = {isa = PBXFileReference; lastKnownFileType = file; path = ConcurrencyTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
OBJ_10 /* AtomicInt.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AtomicInt.swift; sourceTree = "<group>"; };
Expand Down Expand Up @@ -83,6 +71,25 @@
/* End PBXFrameworksBuildPhase section */

/* Begin PBXGroup section */
41B9483E210A4744007E59C8 /* Executor */ = {
isa = PBXGroup;
children = (
41B9483F210A4744007E59C8 /* SerialSequenceExecutor.swift */,
41B94840210A4744007E59C8 /* SequenceExecutor.swift */,
41B94841210A4744007E59C8 /* ConcurrentSequenceExecutor.swift */,
41B94842210A4744007E59C8 /* Task.swift */,
);
path = Executor;
sourceTree = "<group>";
};
41B94847210A4756007E59C8 /* Executor */ = {
isa = PBXGroup;
children = (
41B94848210A4756007E59C8 /* ConcurrentSequenceExecutorTests.swift */,
);
path = Executor;
sourceTree = "<group>";
};
OBJ_13 /* Tests */ = {
isa = PBXGroup;
children = (
Expand All @@ -94,6 +101,7 @@
OBJ_14 /* ConcurrencyTests */ = {
isa = PBXGroup;
children = (
41B94847210A4756007E59C8 /* Executor */,
OBJ_15 /* AtomicBoolTests.swift */,
OBJ_16 /* AtomicIntTests.swift */,
OBJ_17 /* AtomicReferenceTests.swift */,
Expand Down Expand Up @@ -133,6 +141,7 @@
OBJ_8 /* Concurrency */ = {
isa = PBXGroup;
children = (
41B9483E210A4744007E59C8 /* Executor */,
OBJ_9 /* AtomicBool.swift */,
OBJ_10 /* AtomicInt.swift */,
OBJ_11 /* AtomicReference.swift */,
Expand Down Expand Up @@ -178,20 +187,6 @@
productReference = "Concurrency::ConcurrencyTests::Product" /* ConcurrencyTests.xctest */;
productType = "com.apple.product-type.bundle.unit-test";
};
"Concurrency::SwiftPMPackageDescription" /* ConcurrencyPackageDescription */ = {
isa = PBXNativeTarget;
buildConfigurationList = OBJ_33 /* Build configuration list for PBXNativeTarget "ConcurrencyPackageDescription" */;
buildPhases = (
OBJ_36 /* Sources */,
);
buildRules = (
);
dependencies = (
);
name = ConcurrencyPackageDescription;
productName = ConcurrencyPackageDescription;
productType = "com.apple.product-type.framework";
};
/* End PBXNativeTarget section */

/* Begin PBXProject section */
Expand All @@ -213,8 +208,6 @@
projectRoot = "";
targets = (
"Concurrency::Concurrency" /* Concurrency */,
"Concurrency::SwiftPMPackageDescription" /* ConcurrencyPackageDescription */,
"Concurrency::ConcurrencyPackageTests::ProductTarget" /* ConcurrencyPackageTests */,
"Concurrency::ConcurrencyTests" /* ConcurrencyTests */,
);
};
Expand All @@ -225,27 +218,24 @@
isa = PBXSourcesBuildPhase;
buildActionMask = 0;
files = (
41B94846210A4744007E59C8 /* Task.swift in Sources */,
OBJ_27 /* AtomicBool.swift in Sources */,
41B94844210A4744007E59C8 /* SequenceExecutor.swift in Sources */,
41B94845210A4744007E59C8 /* ConcurrentSequenceExecutor.swift in Sources */,
OBJ_28 /* AtomicInt.swift in Sources */,
OBJ_29 /* AtomicReference.swift in Sources */,
41B94843210A4744007E59C8 /* SerialSequenceExecutor.swift in Sources */,
OBJ_30 /* CountDownLatch.swift in Sources */,
);
runOnlyForDeploymentPostprocessing = 0;
};
OBJ_36 /* Sources */ = {
isa = PBXSourcesBuildPhase;
buildActionMask = 0;
files = (
OBJ_37 /* Package.swift in Sources */,
);
runOnlyForDeploymentPostprocessing = 0;
};
OBJ_47 /* Sources */ = {
isa = PBXSourcesBuildPhase;
buildActionMask = 0;
files = (
OBJ_48 /* AtomicBoolTests.swift in Sources */,
OBJ_49 /* AtomicIntTests.swift in Sources */,
41B94849210A4756007E59C8 /* ConcurrentSequenceExecutorTests.swift in Sources */,
OBJ_50 /* AtomicReferenceTests.swift in Sources */,
OBJ_51 /* CountDownLatchTests.swift in Sources */,
);
Expand All @@ -254,11 +244,6 @@
/* End PBXSourcesBuildPhase section */

/* Begin PBXTargetDependency section */
OBJ_42 /* PBXTargetDependency */ = {
isa = PBXTargetDependency;
target = "Concurrency::ConcurrencyTests" /* ConcurrencyTests */;
targetProxy = 412CDD2E20B88EAB00AF5890 /* PBXContainerItemProxy */;
};
OBJ_54 /* PBXTargetDependency */ = {
isa = PBXTargetDependency;
target = "Concurrency::Concurrency" /* Concurrency */;
Expand Down Expand Up @@ -336,24 +321,6 @@
};
name = Debug;
};
OBJ_34 /* Debug */ = {
isa = XCBuildConfiguration;
buildSettings = {
LD = /usr/bin/true;
OTHER_SWIFT_FLAGS = "-swift-version 4 -I $(TOOLCHAIN_DIR)/usr/lib/swift/pm/4 -target x86_64-apple-macosx10.10 -sdk /Applications/Xcode.9.3.0.9E145.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk";
SWIFT_VERSION = 4.0;
};
name = Debug;
};
OBJ_35 /* Release */ = {
isa = XCBuildConfiguration;
buildSettings = {
LD = /usr/bin/true;
OTHER_SWIFT_FLAGS = "-swift-version 4 -I $(TOOLCHAIN_DIR)/usr/lib/swift/pm/4 -target x86_64-apple-macosx10.10 -sdk /Applications/Xcode.9.3.0.9E145.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk";
SWIFT_VERSION = 4.0;
};
name = Release;
};
OBJ_4 /* Release */ = {
isa = XCBuildConfiguration;
buildSettings = {
Expand All @@ -375,18 +342,6 @@
};
name = Release;
};
OBJ_40 /* Debug */ = {
isa = XCBuildConfiguration;
buildSettings = {
};
name = Debug;
};
OBJ_41 /* Release */ = {
isa = XCBuildConfiguration;
buildSettings = {
};
name = Release;
};
OBJ_45 /* Debug */ = {
isa = XCBuildConfiguration;
buildSettings = {
Expand Down Expand Up @@ -446,24 +401,6 @@
defaultConfigurationIsVisible = 0;
defaultConfigurationName = Release;
};
OBJ_33 /* Build configuration list for PBXNativeTarget "ConcurrencyPackageDescription" */ = {
isa = XCConfigurationList;
buildConfigurations = (
OBJ_34 /* Debug */,
OBJ_35 /* Release */,
);
defaultConfigurationIsVisible = 0;
defaultConfigurationName = Release;
};
OBJ_39 /* Build configuration list for PBXAggregateTarget "ConcurrencyPackageTests" */ = {
isa = XCConfigurationList;
buildConfigurations = (
OBJ_40 /* Debug */,
OBJ_41 /* Release */,
);
defaultConfigurationIsVisible = 0;
defaultConfigurationName = Release;
};
OBJ_44 /* Build configuration list for PBXNativeTarget "ConcurrencyTests" */ = {
isa = XCConfigurationList;
buildConfigurations = (
Expand Down
8 changes: 7 additions & 1 deletion README.md
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Expand Up @@ -31,6 +31,12 @@ Provides locking-free synchronization of a mutable object reference. It provides
### `CountDownLatch`
A utility class that allows coordination between threads. A count down latch starts with an initial count. Threads can then decrement the count until it reaches zero, at which point, the suspended waiting thread shall proceed. A `CountDownLatch` behaves differently from a `DispatchSemaphore` once the latch is open. Unlike a semaphore where subsequent waits would still block the caller thread, once a `CountDownLatch` is open, all subsequent waits can directly passthrough.

### `ConcurrentSequenceExecutor`
An execution utility that executes sequences of tasks and returns the final result in a highly concurrent environment.

### `SerialSequenceExecutor`
A debugging executor that executes sequences of tasks and returns the final result serially on the caller thread.

## Installation

### Carthage
Expand Down Expand Up @@ -88,4 +94,4 @@ Or you can follow the steps above to generate a Xcode project and run tests with


## License
[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fuber%2Fswift-concurrency.svg?type=large)](https://app.fossa.io/projects/git%2Bgithub.com%2Fuber%2Fswift-concurrency?ref=badge_large)
[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fuber%2Fswift-concurrency.svg?type=large)](https://app.fossa.io/projects/git%2Bgithub.com%2Fuber%2Fswift-concurrency?ref=badge_large)
114 changes: 114 additions & 0 deletions Sources/Concurrency/Executor/ConcurrentSequenceExecutor.swift
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@@ -0,0 +1,114 @@
//
// Copyright (c) 2018. Uber Technologies
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

import Foundation

/// An executor that executes sequences of tasks concurrently.
///
/// - seeAlso: `SequenceExecutor`.
/// - seeAlso: `Task`.
public class ConcurrentSequenceExecutor: SequenceExecutor {

/// Initializer.
///
/// - parameter name: The name of the executor.
/// - parameter qos: The quality of service of this executor. This
/// defaults to `userInitiated`.
public init(name: String, qos: DispatchQoS = .userInitiated) {
taskQueue = DispatchQueue(label: "Executor.taskQueue-\(name)", qos: qos, attributes: .concurrent)
}

/// Execute a sequence of tasks concurrently from the given initial task.
///
/// - parameter initialTask: The root task of the sequence of tasks
/// to be executed.
/// - parameter execution: The execution defining the sequence of tasks.
/// When a task completes its execution, this closure is invoked with
/// the task and its produced result. This closure is invoked from
/// multiple threads concurrently, therefore it must be thread-safe.
/// The tasks provided by this closure are executed concurrently.
/// - returns: The execution handle that allows control and monitoring
/// of the sequence of tasks being executed.
public func executeSequence<SequenceResultType>(from initialTask: Task, with execution: @escaping (Task, Any) -> SequenceExecution<SequenceResultType>) -> SequenceExecutionHandle<SequenceResultType> {
let handle: SynchronizedSequenceExecutionHandle<SequenceResultType> = SynchronizedSequenceExecutionHandle()
execute(initialTask, with: handle, execution)
return handle
}

// MARK: - Private

private let taskQueue: DispatchQueue

private func execute<SequenceResultType>(_ task: Task, with sequenceHandle: SynchronizedSequenceExecutionHandle<SequenceResultType>, _ execution: @escaping (Task, Any) -> SequenceExecution<SequenceResultType>) {
taskQueue.async {
guard !sequenceHandle.isCancelled else {
return
}

let result = task.typeErasedExecute()
let nextExecution = execution(task, result)
switch nextExecution {
case .continueSequence(let nextTask):
self.execute(nextTask, with: sequenceHandle, execution)
case .endOfSequence(let result):
sequenceHandle.sequenceDidComplete(with: result)
}
}
}
}

private class SynchronizedSequenceExecutionHandle<SequenceResultType>: SequenceExecutionHandle<SequenceResultType> {

private let latch = CountDownLatch(count: 1)
private let didCancel = AtomicBool(initialValue: false)

// Use a lock to ensure result is properly accessed, since the read
// `await` method may be invoked on a different thread than the write
// `sequenceDidComplete` method.
private let resultLock = NSRecursiveLock()
private var result: SequenceResultType?

fileprivate var isCancelled: Bool {
return didCancel.value
}

fileprivate override func await(withTimeout timeout: TimeInterval?) throws -> SequenceResultType {
let didComplete = latch.await(timeout: timeout)
if !didComplete {
throw SequenceExecutionError.awaitTimeout
}

resultLock.lock()
defer {
resultLock.unlock()
}
// If latch was counted down, the result must have been set. Therefore,
// this forced unwrap is safe.
return result!
}

fileprivate func sequenceDidComplete(with result: SequenceResultType) {
resultLock.lock()
self.result = result
resultLock.unlock()

latch.countDown()
}

fileprivate override func cancel() {
didCancel.compareAndSet(expect: false, newValue: true)
}
}
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