Using Modern C++ In Anger Todd L. Montgomery @toddlmontgomery Aeron - - PowerPoint PPT Presentation

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Using Modern C++ In Anger Todd L. Montgomery @toddlmontgomery Aeron - - PowerPoint PPT Presentation

Mar 28, 2024 1.01k likes •2.03k views

StoneTor Using Modern C++ In Anger Todd L. Montgomery @toddlmontgomery Aeron and C++? What constitutes Modern C++ ? How Aeron Adopts Modern C++? What Lessons were learned? Whats Next ? Aeron and C++? Truly modern

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Using Modern C++ In Anger

Todd L. Montgomery @toddlmontgomery

StoneTor

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  • Aeron and C++?
  • What constitutes Modern C++?
  • How Aeron Adopts Modern C++?
  • What Lessons were learned?
  • What’s Next?
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Aeron and C++?

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Truly modern messaging transport

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Feature Bloat & Complexity

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Not Fast Enough

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Low & Predictable Latency is key

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We are in a new world

Multi-core, Multi-socket, Cloud...

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We are in a new world

UDP, IPC, InfiniBand,
 RDMA, PCI-e Multi-core, Multi-socket, Cloud...

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Aeron is trying a new approach

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The Team

Todd Montgomery Richard Warburton Martin Thompson

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Publishers Subscribers Channel Stream

Messaging

Channel

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

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Composable Design

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OSI layer 4 Transport for message oriented streams

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OSI Layer 4 (Transport) Services

  • 1. Connection Oriented Communication
  • 2. Reliability
  • 3. Flow Control
  • 4. Congestion Avoidance/Control
  • 5. Multiplexing
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Multi-Everything World!

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Publishers Subscribers Channel Stream

Multi-Everything World

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Design Principles

  • 1. Garbage free in steady state running
  • 2. Smart Batching in the message path
  • 3. Wait-free algos in the message path
  • 4. Non-blocking IO in the message path
  • 5. No exceptional cases in message path
  • 6. Apply the Single Writer Principle
  • 7. Prefer unshared state
  • 8. Avoid unnecessary data copies
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Publisher Subscriber Subscriber Publisher

Architecture

IPC Log Buffer

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Sender Receiver Receiver Sender Publisher Subscriber Subscriber Publisher

Architecture

Media IPC Log Buffer Media (UDP, InfiniBand, PCI-e 3.0)

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Conductor Sender Receiver Conductor Receiver Sender Publisher Subscriber Subscriber Publisher Admin Events

Architecture

Admin Events Media IPC Log Buffer Media (UDP, InfiniBand, PCI-e 3.0) Function/Method Call Volatile Fields & Queues

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Client Media Driver Media Driver Conductor Sender Receiver Conductor Receiver Sender Client Publisher Conductor Conductor Subscriber Subscriber Publisher Admin Events

Architecture

Admin Events Media IPC Log Buffer IPC Ring/Broadcast Buffer Media (UDP, InfiniBand, PCI-e 3.0) Function/Method Call Volatile Fields & Queues

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C++?

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Client Media Driver Media Driver Conductor Sender Receiver Conductor Receiver Sender Client Publisher Conductor Conductor Subscriber Subscriber Publisher Admin Events

Architecture

Admin Events Media IPC Log Buffer IPC Ring/Broadcast Buffer Media (UDP, InfiniBand, PCI-e 3.0) Function/Method Call Volatile Fields & Queues

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Client Media Driver Media Driver Conductor Sender Receiver Conductor Receiver Sender Client Publisher Conductor Conductor Subscriber Subscriber Publisher Admin Events

Architecture

Admin Events Media IPC Log Buffer IPC Ring/Broadcast Buffer Media (UDP, InfiniBand, PCI-e 3.0) Function/Method Call Volatile Fields & Queues Client

  • Application API
  • Java, C, C++, C#, etc.
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The Media Driver is (currently) Java…

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What constitutes Modern C++?

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Modern C++

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Resource Ownership & Lifetime

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Modern C++

  • Idioms (RAII, etc.)
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std::lock_guard std::unique_ptr

Resource Acquisition is Initialization (RAII)

http://en.cppreference.com/w/cpp/language/raii

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Modern C++

  • Idioms (RAII, etc.)
  • Smart Pointers
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std::shared_ptr std::unique_ptr std::weak_ptr

Smart Pointers

http://en.cppreference.com/w/cpp/memory

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Modern C++

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

  • Idioms (RAII, etc.)
  • Smart Pointers
  • Lambda's & Function Objects
  • Atomics (std::atomic)
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std::atomic<bool> std::atomic_flag

Atomic Operations

http://en.cppreference.com/w/cpp/atomic

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Modern C++

  • Idioms (RAII, etc.)
  • Smart Pointers
  • Lambda's & Function Objects
  • Atomics (std::atomic)
  • Thread Support
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std::thread std::mutex std::promise std::future

Thread Support

http://en.cppreference.com/w/cpp/thread

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Modern C++

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

  • Idioms (RAII, etc.)
  • Smart Pointers
  • Lambda's & Function Objects
  • Atomics (std::atomic)
  • Thread Support
  • Move Construction/Assignment
  • Toolchain (Build/Test)
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CMake Google Test Google Mock etc.

Modern Toolchain

https://cmake.org/ https://github.com/google/googletest

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How Aeron Adopts Modern C++?

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Smart Pointers

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Lambda’s & Function Objects

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Thread Support

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What Lessons were learned?

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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)
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Lessons

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

  • Give in to Smart Pointers
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RAII & Smart Pointers

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

  • Give in to Smart Pointers
  • Explicit Coupling
  • Explicit Scoping
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[insert excuse Y] … Escape Analysis Value Types …

Stack Allocation (Lack of)

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Lessons

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

  • Much more than you think
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Move Construction/Assignment

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

  • Much more than you think
  • Sometimes/Often better to copy
  • Optimization Interactions
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Move Construction/Assignment

  • Much more than you think
  • Sometimes/Often better to copy
  • Optimization Interactions
  • When you have to do it… why?!?
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Lessons

  • Idioms (RAII, etc.)
  • Stack Allocation
  • Smart Pointers
  • Lambda's & Function Objects
  • Atomics (std::atomic)
  • Thread Support
  • Move Construction/Assignment
  • Toolchain (Build/Test)
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Client Media Driver Media Driver Conductor Sender Receiver Conductor Receiver Sender Client Publisher Conductor Conductor Subscriber Subscriber Publisher Admin Events

Architecture

Admin Events Media IPC Log Buffer IPC Ring/Broadcast Buffer Media (UDP, InfiniBand, PCI-e 3.0) Function/Method Call Volatile Fields & Queues

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Data Structures (Shared Memory)

  • IPC Ring Buffers
  • IPC Broadcast Buffers
  • IPC Log Buffers
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Creates a


replicated persistent log


  • f messages

What Aeron does

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Tail File

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Tail File Message 1 Header

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Tail File Message 1 Header Message 2 Header

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Tail File Message 1 Header Message 2 Header

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Tail File Message 1 Header Message 2 Header Message 3

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Tail File Message 1 Header Message 2 Header Message 3 Header

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Log Buffer File

Term 0 Term 1 Term 2 Term Meta Data 0 Term Meta Data 2 Term Meta Data 1 Log Meta Data

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Log Buffer File

Term 0 Term 1 Term 2 Term Meta Data 0 Term Meta Data 2 Term Meta Data 1 Log Meta Data

Atomic & Ordered Operations

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Position

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Unique identification of a byte within each stream

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

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Position counters are the key to
 flow control and monitoring

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Statistics & Position Counters are accessible in shared memory

Atomic & Ordered Operations

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Multiple Challenges

  • Size (and Layout)
  • Memory Models (C++11 to Java)
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Size

Matters

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Size Matters (Atomics)

  • Not designed for arbitrary memory
  • Size not the same as the types
  • Concerned only with operations
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Memory Models

  • Interoperability with JMM
  • std::memory_order fit for purpose
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So… Aeron uses its own atomic

  • perations C/C++ functions

(JMM compatible)

* gcc x86_64 initially contributed by phaynes (phaynes@threatmetrix.com)

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What’s Next?

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Finished a few passes of
 Profiling and Tuning

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C++ to C++ 32+ Million messages per second

IPC, 32-byte Messages

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C++: 32M msg/sec Java: 30M msg/sec .NET: 15M msg/sec

IPC, 32-byte Messages

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Replication Services Aeron Core Persistence Performance C/C++ Driver Multi Unicast Send Efficient FEC Encryption/Security

1.0!!

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In closing…

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https://github.com/real-logic/Aeron

Where can I find it?

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Aeron: https://github.com/real-logic/Aeron Twitter: @toddlmontgomery

Thank You!

Questions?