Modern C++ Old Dog, New Tricks Todd L.

Transcription

1 StoneTor Modern C++ Old Dog, New Tricks Todd L.

2 C++ is so old

3 Languages are Tools Learning Tools is Good

4 There are only two kinds of languages: the ones people complain about and the ones nobody uses. Bjarne Stroustrup

5 Aeron and C++? ReactiveSocket and C++? What constitutes Modern C++? What Lessons were learned?

6 Aeron and C++?

7 Truly modern messaging transport

8 Feature Bloat & Complexity

9 Not Fast Enough

10 Low & Predictable Latency is key

11 We are in a new world Multi-core, Multi-socket, Cloud...

12 We are in a new world Multi-core, Multi-socket, Cloud... UDP, IPC, InfiniBand, RDMA, PCI-e

13 Aeron is trying a new approach

14 The Team Todd Montgomery Richard Warburton Martin Thompson

15 Messaging Publishers Channel Subscribers Stream Channel

16 A library, not a framework, on which other abstractions and applications can be built

17 Composable Design

18 OSI layer 4 Transport for message oriented streams

19 OSI Layer 4 (Transport) Services 1. Connection Oriented Communication 2. Reliability 3. Flow Control 4. Congestion Avoidance/Control 5. Multiplexing

20 Architecture Publisher Subscriber Subscriber Publisher IPC Log Buffer

21 Architecture Publisher Sender Receiver Subscriber Media Subscriber Receiver Sender Publisher IPC Log Buffer Media (UDP, InfiniBand, PCI-e 3.0)

22 Architecture Publisher Sender Receiver Subscriber Admin Media Events Conductor Conductor Events Admin Subscriber Receiver Sender Publisher IPC Log Buffer Media (UDP, InfiniBand, PCI-e 3.0) Function/Method Call Volatile Fields & Queues

23 Architecture Client Media Driver Media Driver Client Publisher Sender Receiver Subscriber Admin Events Conductor Conductor Media Conductor Conductor Events Admin Subscriber Receiver Sender Publisher IPC Log Buffer Media (UDP, InfiniBand, PCI-e 3.0) Function/Method Call Volatile Fields & Queues IPC Ring/Broadcast Buffer

24 C++?

25 Architecture Client Media Driver Media Driver Client Publisher Sender Receiver Subscriber Admin Events Conductor Conductor Media Conductor Conductor Events Admin Subscriber Receiver Sender Publisher IPC Log Buffer Media (UDP, InfiniBand, PCI-e 3.0) Function/Method Call Volatile Fields & Queues IPC Ring/Broadcast Buffer

26 Architecture Client Media Driver Media Driver Client Publisher Sender Receiver Subscriber Admin Events Conductor Conductor Media Conductor Conductor Events Admin Subscriber Receiver Sender Publisher IPC Log Buffer Media (UDP, InfiniBand, PCI-e 3.0) Function/Method Call Volatile Fields & Queues IPC Ring/Broadcast Buffer Client Application API Java, C, C++, C#, etc.

27 The Media Driver is (currently) Java

28 currently

29 ReactiveSocket and C++?

30 Today, Asynchronous is the norm

31 Asynchrony The Lure of Complexity The Need for Simplicity

32 Asynchrony Composition is hard

33 ReactiveX

34 Observables

35 Challenges 1. Non-Blocking Back Pressure 2. Heterogeneous Connectivity

36 Dealing with Back Pressure 1. Reative Streams 2. RxJava Akka Streams 4. java.util.concurrent.flow (JEP 266)

37 Rx Heterogeneous Connectivity 1. ReactiveSocket

38 C++?

39 Rx Heterogeneous Connectivity 1. ReactiveSocket Protocol Reactive Streams - Application API Java, JS, C++, Go, etc. What do you call a 1 language protocol?

40 What constitutes Modern C++?

41

42 Within C++, there is a much smaller and cleaner language struggling to get out. And no, that smaller and cleaner language is not Java or C#. Bjarne Stroustrup

43 Modern C++ Main Concept(s)

44 Resource Ownership & Lifetime

45 Resource Ownership & Lifetime Scope Coupling Dependency

46 Modern C++ Idioms (RAII, etc.)

47 Resource Acquisition is Initialization (RAII) std::lock_guard std::unique_ptr std::shared_ptr

48 Other C++ Idioms PImpl CRTP Erase-Remove SFINAE* * Substitution Failure is Not An Error

49 Modern C++ Idioms (RAII, etc.) Smart Pointers

50 Smart Pointers std::shared_ptr std::unique_ptr std::weak_ptr

51 Smart Pointers

52 Smart Pointers & Ownership

53 Modern C++ Idioms (RAII, etc.) Smart Pointers Lambda's & Function Objects

54 Lambda s & Function Objects

55 Modern C++ Idioms (RAII, etc.) Smart Pointers Lambda's & Function Objects Atomics (std::atomic)

56 Atomic Operations std::atomic<bool> std::atomic_flag std::atomic<int>

57 Modern C++ Idioms (RAII, etc.) Smart Pointers Lambda's & Function Objects Atomics (std::atomic) Thread Support

58 Thread Support std::thread std::mutex std::async std::promise std::future

59 Thread Support

60 Modern C++ Idioms (RAII, etc.) Smart Pointers Lambda's & Function Objects Atomics (std::atomic) Thread Support Move Construction/Assignment *

61 Move Construction/Assignment Moving vs. Copying Ownership?

62 Modern C++ Idioms (RAII, etc.) Smart Pointers Lambda's & Function Objects Atomics (std::atomic) Thread Support Move Construction/Assignment * Toolchain (Build/Test)

63 Modern Toolchain CMake Google Test Google Mock Google Benchmark etc.

64 What Lessons were learned?

65 Lessons - What do you think? Idioms (RAII, etc.) Stack Allocation Smart Pointers Lambda's & Function Objects Atomics (std::atomic) Thread Support Move Construction/Assignment Toolchain (Build/Test)

66 Lessons Idioms (RAII, etc.) Stack Allocation Smart Pointers Lambda's & Function Objects Atomics (std::atomic) Thread Support Move Construction/Assignment Toolchain (Build/Test)

67

68 RAII & Smart Pointers Give in to Smart Pointers

69 Smart Pointers But But But CYCLES!!!

70 Dealing with Cycles std::weak_ptr std::enable_shared_from_this Design them out Techniques & Indirection RCU / QSBR Deferred & Unordered Destruction (GCPP)

71 RAII & Smart Pointers Give in to Smart Pointers Explicit Coupling

72 RAII & Smart Pointers Give in to Smart Pointers Explicit Coupling Explicit Scoping

73 RAII & Smart Pointers Give in to Smart Pointers Explicit Coupling Explicit Scoping Explicit Dependency

74 Explicit Coupling / Scope / Dependency Hiding Complexity is not Dealing with Complexity

75 Explicit Coupling / Scope / Dependency Speaks to Quality Build Quality In

76 Coupling / Scope / Dependency Enforced Decoupling & Isolation.

77 More Important? What a language provides? What a language takes away?

78 Explicit Coupling / Scope / Dependency Deal with it up front Pays off massively later If it hurts, do it more often

79 Lessons Idioms (RAII, etc.) Stack Allocation Smart Pointers Lambda's & Function Objects Atomics (std::atomic) Thread Support Move Construction/Assignment Toolchain (Build/Test)

80 Stack Allocation (Lack of) Not Needed Because Escape Analysis Value Types ${EXCUSE}[i]

81

82

83 Stack Allocation Mechanism is NOT a set of features

84 Stack Allocation Stack Function Objects very very low cost deferred/conditional execution

85 Lessons Idioms (RAII, etc.) Stack Allocation Smart Pointers Lambda's & Function Objects Atomics (std::atomic) Thread Support Move Construction/Assignment Toolchain (Build/Test)

86

87 Move Construction/Assignment Much more than you think

88 Move Construction/Assignment Much more than you think Sometimes/Often better to copy

89 Move Construction/Assignment Much more than you think Sometimes/Often better to copy Optimization Interactions (e.g. SSO)

90 Move Construction/Assignment Much more than you think Sometimes/Often better to copy Optimization Interactions (e.g. SSO) When you have to do it why?!?

91 Lessons Idioms (RAII, etc.) Stack Allocation Smart Pointers Lambda's & Function Objects Atomics (std::atomic) Thread Support Move Construction/Assignment Toolchain (Build/Test)

92

93 Architecture Client Media Driver Media Driver Client Publisher Sender Receiver Subscriber Admin Events Conductor Conductor Media Conductor Conductor Events Admin Subscriber Receiver Sender Publisher IPC Log Buffer Media (UDP, InfiniBand, PCI-e 3.0) Function/Method Call Volatile Fields & Queues IPC Ring/Broadcast Buffer

94 Data Structures (Shared Memory) IPC Ring Buffers IPC Broadcast Buffers IPC Log Buffers

95 What Aeron does Creates a replicated persistent log of messages

96 Atomic & Ordered Operations Log Buffer File Term 0 Term 1 Term 2 Log Meta Data

97 Position

98 Unique identification of a byte within each stream

99 Publishers, Senders, Receivers, and Subscribers all keep position counters

100 Position counters are the key to flow control and monitoring

101 Statistics & Position Counters are accessible in shared memory Atomic & Ordered Operations

102 Multiple Challenges Size (and Layout) Memory Models (C++11 to Java)

103 Size Matters

104

105 Size Matters (Atomics) Not designed for arbitrary memory Size not the same as the types Concerned only with operations

106 Memory Models Interoperability with JMM std::memory_order fit for purpose

107 So Aeron uses its own atomic operations C/C++ functions (JMM compatible) * gcc x86_64 initially contributed by phaynes (phaynes@threatmetrix.com)

108 Wrapping Up

109 Languages are Tools Fit for purpose Add to your toolbox!

110 There are more useful systems developed in languages deemed awful than in languages praised for being beautiful--many more. Bjarne Stroustrup (via Jason Pontin)

111

112 Where can I find them? reactivesocket-cpp

113 Questions? Aeron: ReactiveSocket: Thank You!