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Added some concurrency primitives

This commit is contained in:
ezratl 2019-02-10 21:36:58 -05:00
parent 6ef357120d
commit 4db87d744d
16 changed files with 5427 additions and 50 deletions
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12
piScan_backend/src/PiScanServer.cpp Normal file
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/*
* PiScanServer.cpp
*
* Created on: Feb 10, 2019
* Author: ezra
*/
int main(int argc, char** argv){
return 0;
}

18
piScan_backend/src/ScanStateMachine.cpp
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/*
* ScanStateMachine.cpp
*
* Created on: Oct 22, 2018
* Author: ezra
*/
#include "ScanStateMachine.h"
ScanStateMachine::ScanStateMachine() {
// TODO Auto-generated constructor stub
}
ScanStateMachine::~ScanStateMachine() {
// TODO Auto-generated destructor stub
}

17
piScan_backend/src/ScanStateMachine.h
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/*
* ScanStateMachine.h
*
* Created on: Oct 22, 2018
* Author: ezra
*/
#ifndef SCANSTATEMACHINE_H_
#define SCANSTATEMACHINE_H_
class ScanStateMachine {
public:
ScanStateMachine();
virtual ~ScanStateMachine();
};
#endif /* SCANSTATEMACHINE_H_ */

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piScan_backend/src/external/atomicops.h vendored Normal file
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// ©2013-2016 Cameron Desrochers.
// Distributed under the simplified BSD license (see the license file that
// should have come with this header).
// Uses Jeff Preshing's semaphore implementation (under the terms of its
// separate zlib license, embedded below).
#pragma once
// Provides portable (VC++2010+, Intel ICC 13, GCC 4.7+, and anything C++11 compliant) implementation
// of low-level memory barriers, plus a few semi-portable utility macros (for inlining and alignment).
// Also has a basic atomic type (limited to hardware-supported atomics with no memory ordering guarantees).
// Uses the AE_* prefix for macros (historical reasons), and the "moodycamel" namespace for symbols.
#include <cassert>
#include <type_traits>
#include <cerrno>
#include <cstdint>
#include <ctime>
// Platform detection
#if defined(__INTEL_COMPILER)
#define AE_ICC
#elif defined(_MSC_VER)
#define AE_VCPP
#elif defined(__GNUC__)
#define AE_GCC
#endif
#if defined(_M_IA64) || defined(__ia64__)
#define AE_ARCH_IA64
#elif defined(_WIN64) || defined(__amd64__) || defined(_M_X64) || defined(__x86_64__)
#define AE_ARCH_X64
#elif defined(_M_IX86) || defined(__i386__)
#define AE_ARCH_X86
#elif defined(_M_PPC) || defined(__powerpc__)
#define AE_ARCH_PPC
#else
#define AE_ARCH_UNKNOWN
#endif
// AE_UNUSED
#define AE_UNUSED(x) ((void)x)
// AE_NO_TSAN
#if defined(__has_feature)
#if __has_feature(thread_sanitizer)
#define AE_NO_TSAN __attribute__((no_sanitize("thread")))
#else
#define AE_NO_TSAN
#endif
#else
#define AE_NO_TSAN
#endif
// AE_FORCEINLINE
#if defined(AE_VCPP) || defined(AE_ICC)
#define AE_FORCEINLINE __forceinline
#elif defined(AE_GCC)
//#define AE_FORCEINLINE __attribute__((always_inline))
#define AE_FORCEINLINE inline
#else
#define AE_FORCEINLINE inline
#endif
// AE_ALIGN
#if defined(AE_VCPP) || defined(AE_ICC)
#define AE_ALIGN(x) __declspec(align(x))
#elif defined(AE_GCC)
#define AE_ALIGN(x) __attribute__((aligned(x)))
#else
// Assume GCC compliant syntax...
#define AE_ALIGN(x) __attribute__((aligned(x)))
#endif
// Portable atomic fences implemented below:
namespace moodycamel {
enum memory_order {
memory_order_relaxed,
memory_order_acquire,
memory_order_release,
memory_order_acq_rel,
memory_order_seq_cst,
// memory_order_sync: Forces a full sync:
// #LoadLoad, #LoadStore, #StoreStore, and most significantly, #StoreLoad
memory_order_sync = memory_order_seq_cst
};
} // end namespace moodycamel
#if (defined(AE_VCPP) && (_MSC_VER < 1700 || defined(__cplusplus_cli))) || (defined(AE_ICC) && __INTEL_COMPILER < 1600)
// VS2010 and ICC13 don't support std::atomic_*_fence, implement our own fences
#include <intrin.h>
#if defined(AE_ARCH_X64) || defined(AE_ARCH_X86)
#define AeFullSync _mm_mfence
#define AeLiteSync _mm_mfence
#elif defined(AE_ARCH_IA64)
#define AeFullSync __mf
#define AeLiteSync __mf
#elif defined(AE_ARCH_PPC)
#include <ppcintrinsics.h>
#define AeFullSync __sync
#define AeLiteSync __lwsync
#endif
#ifdef AE_VCPP
#pragma warning(push)
#pragma warning(disable: 4365) // Disable erroneous 'conversion from long to unsigned int, signed/unsigned mismatch' error when using `assert`
#ifdef __cplusplus_cli
#pragma managed(push, off)
#endif
#endif
namespace moodycamel {
AE_FORCEINLINE void compiler_fence(memory_order order) AE_NO_TSAN
{
switch (order) {
case memory_order_relaxed: break;
case memory_order_acquire: _ReadBarrier(); break;
case memory_order_release: _WriteBarrier(); break;
case memory_order_acq_rel: _ReadWriteBarrier(); break;
case memory_order_seq_cst: _ReadWriteBarrier(); break;
default: assert(false);
}
}
// x86/x64 have a strong memory model -- all loads and stores have
// acquire and release semantics automatically (so only need compiler
// barriers for those).
#if defined(AE_ARCH_X86) || defined(AE_ARCH_X64)
AE_FORCEINLINE void fence(memory_order order) AE_NO_TSAN
{
switch (order) {
case memory_order_relaxed: break;
case memory_order_acquire: _ReadBarrier(); break;
case memory_order_release: _WriteBarrier(); break;
case memory_order_acq_rel: _ReadWriteBarrier(); break;
case memory_order_seq_cst:
_ReadWriteBarrier();
AeFullSync();
_ReadWriteBarrier();
break;
default: assert(false);
}
}
#else
AE_FORCEINLINE void fence(memory_order order) AE_NO_TSAN
{
// Non-specialized arch, use heavier memory barriers everywhere just in case :-(
switch (order) {
case memory_order_relaxed:
break;
case memory_order_acquire:
_ReadBarrier();
AeLiteSync();
_ReadBarrier();
break;
case memory_order_release:
_WriteBarrier();
AeLiteSync();
_WriteBarrier();
break;
case memory_order_acq_rel:
_ReadWriteBarrier();
AeLiteSync();
_ReadWriteBarrier();
break;
case memory_order_seq_cst:
_ReadWriteBarrier();
AeFullSync();
_ReadWriteBarrier();
break;
default: assert(false);
}
}
#endif
} // end namespace moodycamel
#else
// Use standard library of atomics
#include <atomic>
namespace moodycamel {
AE_FORCEINLINE void compiler_fence(memory_order order) AE_NO_TSAN
{
switch (order) {
case memory_order_relaxed: break;
case memory_order_acquire: std::atomic_signal_fence(std::memory_order_acquire); break;
case memory_order_release: std::atomic_signal_fence(std::memory_order_release); break;
case memory_order_acq_rel: std::atomic_signal_fence(std::memory_order_acq_rel); break;
case memory_order_seq_cst: std::atomic_signal_fence(std::memory_order_seq_cst); break;
default: assert(false);
}
}
AE_FORCEINLINE void fence(memory_order order) AE_NO_TSAN
{
switch (order) {
case memory_order_relaxed: break;
case memory_order_acquire: std::atomic_thread_fence(std::memory_order_acquire); break;
case memory_order_release: std::atomic_thread_fence(std::memory_order_release); break;
case memory_order_acq_rel: std::atomic_thread_fence(std::memory_order_acq_rel); break;
case memory_order_seq_cst: std::atomic_thread_fence(std::memory_order_seq_cst); break;
default: assert(false);
}
}
} // end namespace moodycamel
#endif
#if !defined(AE_VCPP) || (_MSC_VER >= 1700 && !defined(__cplusplus_cli))
#define AE_USE_STD_ATOMIC_FOR_WEAK_ATOMIC
#endif
#ifdef AE_USE_STD_ATOMIC_FOR_WEAK_ATOMIC
#include <atomic>
#endif
#include <utility>
// WARNING: *NOT* A REPLACEMENT FOR std::atomic. READ CAREFULLY:
// Provides basic support for atomic variables -- no memory ordering guarantees are provided.
// The guarantee of atomicity is only made for types that already have atomic load and store guarantees
// at the hardware level -- on most platforms this generally means aligned pointers and integers (only).
namespace moodycamel {
template<typename T>
class weak_atomic
{
public:
AE_NO_TSAN weak_atomic() { }
#ifdef AE_VCPP
#pragma warning(push)
#pragma warning(disable: 4100) // Get rid of (erroneous) 'unreferenced formal parameter' warning
#endif
template<typename U> AE_NO_TSAN weak_atomic(U&& x) : value(std::forward<U>(x)) { }
#ifdef __cplusplus_cli
// Work around bug with universal reference/nullptr combination that only appears when /clr is on
AE_NO_TSAN weak_atomic(nullptr_t) : value(nullptr) { }
#endif
AE_NO_TSAN weak_atomic(weak_atomic const& other) : value(other.load()) { }
AE_NO_TSAN weak_atomic(weak_atomic&& other) : value(std::move(other.load())) { }
#ifdef AE_VCPP
#pragma warning(pop)
#endif
AE_FORCEINLINE operator T() const AE_NO_TSAN { return load(); }
#ifndef AE_USE_STD_ATOMIC_FOR_WEAK_ATOMIC
template<typename U> AE_FORCEINLINE weak_atomic const& operator=(U&& x) AE_NO_TSAN { value = std::forward<U>(x); return *this; }
AE_FORCEINLINE weak_atomic const& operator=(weak_atomic const& other) AE_NO_TSAN { value = other.value; return *this; }
AE_FORCEINLINE T load() const AE_NO_TSAN { return value; }
AE_FORCEINLINE T fetch_add_acquire(T increment) AE_NO_TSAN
{
#if defined(AE_ARCH_X64) || defined(AE_ARCH_X86)
if (sizeof(T) == 4) return _InterlockedExchangeAdd((long volatile*)&value, (long)increment);
#if defined(_M_AMD64)
else if (sizeof(T) == 8) return _InterlockedExchangeAdd64((long long volatile*)&value, (long long)increment);
#endif
#else
#error Unsupported platform
#endif
assert(false && "T must be either a 32 or 64 bit type");
return value;
}
AE_FORCEINLINE T fetch_add_release(T increment) AE_NO_TSAN
{
#if defined(AE_ARCH_X64) || defined(AE_ARCH_X86)
if (sizeof(T) == 4) return _InterlockedExchangeAdd((long volatile*)&value, (long)increment);
#if defined(_M_AMD64)
else if (sizeof(T) == 8) return _InterlockedExchangeAdd64((long long volatile*)&value, (long long)increment);
#endif
#else
#error Unsupported platform
#endif
assert(false && "T must be either a 32 or 64 bit type");
return value;
}
#else
template<typename U>
AE_FORCEINLINE weak_atomic const& operator=(U&& x) AE_NO_TSAN
{
value.store(std::forward<U>(x), std::memory_order_relaxed);
return *this;
}
AE_FORCEINLINE weak_atomic const& operator=(weak_atomic const& other) AE_NO_TSAN
{
value.store(other.value.load(std::memory_order_relaxed), std::memory_order_relaxed);
return *this;
}
AE_FORCEINLINE T load() const AE_NO_TSAN { return value.load(std::memory_order_relaxed); }
AE_FORCEINLINE T fetch_add_acquire(T increment) AE_NO_TSAN
{
return value.fetch_add(increment, std::memory_order_acquire);
}
AE_FORCEINLINE T fetch_add_release(T increment) AE_NO_TSAN
{
return value.fetch_add(increment, std::memory_order_release);
}
#endif
private:
#ifndef AE_USE_STD_ATOMIC_FOR_WEAK_ATOMIC
// No std::atomic support, but still need to circumvent compiler optimizations.
// `volatile` will make memory access slow, but is guaranteed to be reliable.
volatile T value;
#else
std::atomic<T> value;
#endif
};
} // end namespace moodycamel
// Portable single-producer, single-consumer semaphore below:
#if defined(_WIN32)
// Avoid including windows.h in a header; we only need a handful of
// items, so we'll redeclare them here (this is relatively safe since
// the API generally has to remain stable between Windows versions).
// I know this is an ugly hack but it still beats polluting the global
// namespace with thousands of generic names or adding a .cpp for nothing.
extern "C" {
struct _SECURITY_ATTRIBUTES;
__declspec(dllimport) void* __stdcall CreateSemaphoreW(_SECURITY_ATTRIBUTES* lpSemaphoreAttributes, long lInitialCount, long lMaximumCount, const wchar_t* lpName);
__declspec(dllimport) int __stdcall CloseHandle(void* hObject);
__declspec(dllimport) unsigned long __stdcall WaitForSingleObject(void* hHandle, unsigned long dwMilliseconds);
__declspec(dllimport) int __stdcall ReleaseSemaphore(void* hSemaphore, long lReleaseCount, long* lpPreviousCount);
}
#elif defined(__MACH__)
#include <mach/mach.h>
#elif defined(__unix__)
#include <semaphore.h>
#endif
namespace moodycamel
{
// Code in the spsc_sema namespace below is an adaptation of Jeff Preshing's
// portable + lightweight semaphore implementations, originally from
// https://github.com/preshing/cpp11-on-multicore/blob/master/common/sema.h
// LICENSE:
// Copyright (c) 2015 Jeff Preshing
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgement in the product documentation would be
// appreciated but is not required.
// 2. Altered source versions must be plainly marked as such, and must not be
// misrepresented as being the original software.
// 3. This notice may not be removed or altered from any source distribution.
namespace spsc_sema
{
#if defined(_WIN32)
class Semaphore
{
private:
void* m_hSema;
Semaphore(const Semaphore& other);
Semaphore& operator=(const Semaphore& other);
public:
AE_NO_TSAN Semaphore(int initialCount = 0)
{
assert(initialCount >= 0);
const long maxLong = 0x7fffffff;
m_hSema = CreateSemaphoreW(nullptr, initialCount, maxLong, nullptr);
}
AE_NO_TSAN ~Semaphore()
{
CloseHandle(m_hSema);
}
void wait() AE_NO_TSAN
{
const unsigned long infinite = 0xffffffff;
WaitForSingleObject(m_hSema, infinite);
}
bool try_wait() AE_NO_TSAN
{
const unsigned long RC_WAIT_TIMEOUT = 0x00000102;
return WaitForSingleObject(m_hSema, 0) != RC_WAIT_TIMEOUT;
}
bool timed_wait(std::uint64_t usecs) AE_NO_TSAN
{
const unsigned long RC_WAIT_TIMEOUT = 0x00000102;
return WaitForSingleObject(m_hSema, (unsigned long)(usecs / 1000)) != RC_WAIT_TIMEOUT;
}
void signal(int count = 1) AE_NO_TSAN
{
ReleaseSemaphore(m_hSema, count, nullptr);
}
};
#elif defined(__MACH__)
//---------------------------------------------------------
// Semaphore (Apple iOS and OSX)
// Can't use POSIX semaphores due to http://lists.apple.com/archives/darwin-kernel/2009/Apr/msg00010.html
//---------------------------------------------------------
class Semaphore
{
private:
semaphore_t m_sema;
Semaphore(const Semaphore& other);
Semaphore& operator=(const Semaphore& other);
public:
AE_NO_TSAN Semaphore(int initialCount = 0)
{
assert(initialCount >= 0);
semaphore_create(mach_task_self(), &m_sema, SYNC_POLICY_FIFO, initialCount);
}
AE_NO_TSAN ~Semaphore()
{
semaphore_destroy(mach_task_self(), m_sema);
}
void wait() AE_NO_TSAN
{
semaphore_wait(m_sema);
}
bool try_wait() AE_NO_TSAN
{
return timed_wait(0);
}
bool timed_wait(std::int64_t timeout_usecs) AE_NO_TSAN
{
mach_timespec_t ts;
ts.tv_sec = static_cast<unsigned int>(timeout_usecs / 1000000);
ts.tv_nsec = (timeout_usecs % 1000000) * 1000;
// added in OSX 10.10: https://developer.apple.com/library/prerelease/mac/documentation/General/Reference/APIDiffsMacOSX10_10SeedDiff/modules/Darwin.html
kern_return_t rc = semaphore_timedwait(m_sema, ts);
return rc != KERN_OPERATION_TIMED_OUT && rc != KERN_ABORTED;
}
void signal() AE_NO_TSAN
{
semaphore_signal(m_sema);
}
void signal(int count) AE_NO_TSAN
{
while (count-- > 0)
{
semaphore_signal(m_sema);
}
}
};
#elif defined(__unix__)
//---------------------------------------------------------
// Semaphore (POSIX, Linux)
//---------------------------------------------------------
class Semaphore
{
private:
sem_t m_sema;
Semaphore(const Semaphore& other);
Semaphore& operator=(const Semaphore& other);
public:
AE_NO_TSAN Semaphore(int initialCount = 0)
{
assert(initialCount >= 0);
sem_init(&m_sema, 0, initialCount);
}
AE_NO_TSAN ~Semaphore()
{
sem_destroy(&m_sema);
}
void wait() AE_NO_TSAN
{
// http://stackoverflow.com/questions/2013181/gdb-causes-sem-wait-to-fail-with-eintr-error
int rc;
do
{
rc = sem_wait(&m_sema);
}
while (rc == -1 && errno == EINTR);
}
bool try_wait() AE_NO_TSAN
{
int rc;
do {
rc = sem_trywait(&m_sema);
} while (rc == -1 && errno == EINTR);
return !(rc == -1 && errno == EAGAIN);
}
bool timed_wait(std::uint64_t usecs) AE_NO_TSAN
{
struct timespec ts;
const int usecs_in_1_sec = 1000000;
const int nsecs_in_1_sec = 1000000000;
clock_gettime(CLOCK_REALTIME, &ts);
ts.tv_sec += usecs / usecs_in_1_sec;
ts.tv_nsec += (usecs % usecs_in_1_sec) * 1000;
// sem_timedwait bombs if you have more than 1e9 in tv_nsec
// so we have to clean things up before passing it in
if (ts.tv_nsec >= nsecs_in_1_sec) {
ts.tv_nsec -= nsecs_in_1_sec;
++ts.tv_sec;
}
int rc;
do {
rc = sem_timedwait(&m_sema, &ts);
} while (rc == -1 && errno == EINTR);
return !(rc == -1 && errno == ETIMEDOUT);
}
void signal() AE_NO_TSAN
{
sem_post(&m_sema);
}
void signal(int count) AE_NO_TSAN
{
while (count-- > 0)
{
sem_post(&m_sema);
}
}
};
#else
#error Unsupported platform! (No semaphore wrapper available)
#endif
//---------------------------------------------------------
// LightweightSemaphore
//---------------------------------------------------------
class LightweightSemaphore
{
public:
typedef std::make_signed<std::size_t>::type ssize_t;
private:
weak_atomic<ssize_t> m_count;
Semaphore m_sema;
bool waitWithPartialSpinning(std::int64_t timeout_usecs = -1) AE_NO_TSAN
{
ssize_t oldCount;
// Is there a better way to set the initial spin count?
// If we lower it to 1000, testBenaphore becomes 15x slower on my Core i7-5930K Windows PC,
// as threads start hitting the kernel semaphore.
int spin = 10000;
while (--spin >= 0)
{
if (m_count.load() > 0)
{
m_count.fetch_add_acquire(-1);
return true;
}
compiler_fence(memory_order_acquire); // Prevent the compiler from collapsing the loop.
}
oldCount = m_count.fetch_add_acquire(-1);
if (oldCount > 0)
return true;
if (timeout_usecs < 0)
{
m_sema.wait();
return true;
}
if (m_sema.timed_wait(timeout_usecs))
return true;
// At this point, we've timed out waiting for the semaphore, but the
// count is still decremented indicating we may still be waiting on
// it. So we have to re-adjust the count, but only if the semaphore
// wasn't signaled enough times for us too since then. If it was, we
// need to release the semaphore too.
while (true)
{
oldCount = m_count.fetch_add_release(1);
if (oldCount < 0)
return false; // successfully restored things to the way they were
// Oh, the producer thread just signaled the semaphore after all. Try again:
oldCount = m_count.fetch_add_acquire(-1);
if (oldCount > 0 && m_sema.try_wait())
return true;
}
}
public:
AE_NO_TSAN LightweightSemaphore(ssize_t initialCount = 0) : m_count(initialCount)
{
assert(initialCount >= 0);
}
bool tryWait() AE_NO_TSAN
{
if (m_count.load() > 0)
{
m_count.fetch_add_acquire(-1);
return true;
}
return false;
}
void wait() AE_NO_TSAN
{
if (!tryWait())
waitWithPartialSpinning();
}
bool wait(std::int64_t timeout_usecs) AE_NO_TSAN
{
return tryWait() || waitWithPartialSpinning(timeout_usecs);
}
void signal(ssize_t count = 1) AE_NO_TSAN
{
assert(count >= 0);
ssize_t oldCount = m_count.fetch_add_release(count);
assert(oldCount >= -1);
if (oldCount < 0)
{
m_sema.signal(1);
}
}
ssize_t availableApprox() const AE_NO_TSAN
{
ssize_t count = m_count.load();
return count > 0 ? count : 0;
}
};
} // end namespace spsc_sema
} // end namespace moodycamel
#if defined(AE_VCPP) && (_MSC_VER < 1700 || defined(__cplusplus_cli))
#pragma warning(pop)
#ifdef __cplusplus_cli
#pragma managed(pop)
#endif
#endif

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// ©2013-2016 Cameron Desrochers.
// Distributed under the simplified BSD license (see the license file that
// should have come with this header).
#pragma once
#include "atomicops.h"
#include <type_traits>
#include <utility>
#include <cassert>
#include <stdexcept>
#include <new>
#include <cstdint>
#include <cstdlib> // For malloc/free/abort & size_t
#include <memory>
#if __cplusplus > 199711L || _MSC_VER >= 1700 // C++11 or VS2012
#include <chrono>
#endif
// A lock-free queue for a single-consumer, single-producer architecture.
// The queue is also wait-free in the common path (except if more memory
// needs to be allocated, in which case malloc is called).
// Allocates memory sparingly (O(lg(n) times, amortized), and only once if
// the original maximum size estimate is never exceeded.
// Tested on x86/x64 processors, but semantics should be correct for all
// architectures (given the right implementations in atomicops.h), provided
// that aligned integer and pointer accesses are naturally atomic.
// Note that there should only be one consumer thread and producer thread;
// Switching roles of the threads, or using multiple consecutive threads for
// one role, is not safe unless properly synchronized.
// Using the queue exclusively from one thread is fine, though a bit silly.
#ifndef MOODYCAMEL_CACHE_LINE_SIZE
#define MOODYCAMEL_CACHE_LINE_SIZE 64
#endif
#ifndef MOODYCAMEL_EXCEPTIONS_ENABLED
#if (defined(_MSC_VER) && defined(_CPPUNWIND)) || (defined(__GNUC__) && defined(__EXCEPTIONS)) || (!defined(_MSC_VER) && !defined(__GNUC__))
#define MOODYCAMEL_EXCEPTIONS_ENABLED
#endif
#endif
#ifndef MOODYCAMEL_HAS_EMPLACE
#if !defined(_MSC_VER) || _MSC_VER >= 1800 // variadic templates: either a non-MS compiler or VS >= 2013
#define MOODYCAMEL_HAS_EMPLACE 1
#endif
#endif
#ifdef AE_VCPP
#pragma warning(push)
#pragma warning(disable: 4324) // structure was padded due to __declspec(align())
#pragma warning(disable: 4820) // padding was added
#pragma warning(disable: 4127) // conditional expression is constant
#endif
namespace moodycamel {
template<typename T, size_t MAX_BLOCK_SIZE = 512>
class ReaderWriterQueue
{
// Design: Based on a queue-of-queues. The low-level queues are just
// circular buffers with front and tail indices indicating where the
// next element to dequeue is and where the next element can be enqueued,
// respectively. Each low-level queue is called a "block". Each block
// wastes exactly one element's worth of space to keep the design simple
// (if front == tail then the queue is empty, and can't be full).
// The high-level queue is a circular linked list of blocks; again there
// is a front and tail, but this time they are pointers to the blocks.
// The front block is where the next element to be dequeued is, provided
// the block is not empty. The back block is where elements are to be
// enqueued, provided the block is not full.
// The producer thread owns all the tail indices/pointers. The consumer
// thread owns all the front indices/pointers. Both threads read each
// other's variables, but only the owning thread updates them. E.g. After
// the consumer reads the producer's tail, the tail may change before the
// consumer is done dequeuing an object, but the consumer knows the tail
// will never go backwards, only forwards.
// If there is no room to enqueue an object, an additional block (of
// equal size to the last block) is added. Blocks are never removed.
public:
typedef T value_type;
// Constructs a queue that can hold maxSize elements without further
// allocations. If more than MAX_BLOCK_SIZE elements are requested,
// then several blocks of MAX_BLOCK_SIZE each are reserved (including
// at least one extra buffer block).
AE_NO_TSAN explicit ReaderWriterQueue(size_t maxSize = 15)
#ifndef NDEBUG
: enqueuing(false)
,dequeuing(false)
#endif
{
assert(maxSize > 0);
assert(MAX_BLOCK_SIZE == ceilToPow2(MAX_BLOCK_SIZE) && "MAX_BLOCK_SIZE must be a power of 2");
assert(MAX_BLOCK_SIZE >= 2 && "MAX_BLOCK_SIZE must be at least 2");
Block* firstBlock = nullptr;
largestBlockSize = ceilToPow2(maxSize + 1); // We need a spare slot to fit maxSize elements in the block
if (largestBlockSize > MAX_BLOCK_SIZE * 2) {
// We need a spare block in case the producer is writing to a different block the consumer is reading from, and
// wants to enqueue the maximum number of elements. We also need a spare element in each block to avoid the ambiguity
// between front == tail meaning "empty" and "full".
// So the effective number of slots that are guaranteed to be usable at any time is the block size - 1 times the
// number of blocks - 1. Solving for maxSize and applying a ceiling to the division gives us (after simplifying):
size_t initialBlockCount = (maxSize + MAX_BLOCK_SIZE * 2 - 3) / (MAX_BLOCK_SIZE - 1);
largestBlockSize = MAX_BLOCK_SIZE;
Block* lastBlock = nullptr;
for (size_t i = 0; i != initialBlockCount; ++i) {
auto block = make_block(largestBlockSize);
if (block == nullptr) {
#ifdef MOODYCAMEL_EXCEPTIONS_ENABLED
throw std::bad_alloc();
#else
abort();
#endif
}
if (firstBlock == nullptr) {
firstBlock = block;
}
else {
lastBlock->next = block;
}
lastBlock = block;
block->next = firstBlock;
}
}
else {
firstBlock = make_block(largestBlockSize);
if (firstBlock == nullptr) {
#ifdef MOODYCAMEL_EXCEPTIONS_ENABLED
throw std::bad_alloc();
#else
abort();
#endif
}
firstBlock->next = firstBlock;
}
frontBlock = firstBlock;
tailBlock = firstBlock;
// Make sure the reader/writer threads will have the initialized memory setup above:
fence(memory_order_sync);
}
// Note: The queue should not be accessed concurrently while it's
// being moved. It's up to the user to synchronize this.
AE_NO_TSAN ReaderWriterQueue(ReaderWriterQueue&& other)
: frontBlock(other.frontBlock.load()),
tailBlock(other.tailBlock.load()),
largestBlockSize(other.largestBlockSize)
#ifndef NDEBUG
,enqueuing(false)
,dequeuing(false)
#endif
{
other.largestBlockSize = 32;
Block* b = other.make_block(other.largestBlockSize);
if (b == nullptr) {
#ifdef MOODYCAMEL_EXCEPTIONS_ENABLED
throw std::bad_alloc();
#else
abort();
#endif
}
b->next = b;
other.frontBlock = b;
other.tailBlock = b;
}
// Note: The queue should not be accessed concurrently while it's
// being moved. It's up to the user to synchronize this.
ReaderWriterQueue& operator=(ReaderWriterQueue&& other) AE_NO_TSAN
{
Block* b = frontBlock.load();
frontBlock = other.frontBlock.load();
other.frontBlock = b;
b = tailBlock.load();
tailBlock = other.tailBlock.load();
other.tailBlock = b;
std::swap(largestBlockSize, other.largestBlockSize);
return *this;
}
// Note: The queue should not be accessed concurrently while it's
// being deleted. It's up to the user to synchronize this.
AE_NO_TSAN ~ReaderWriterQueue()
{
// Make sure we get the latest version of all variables from other CPUs:
fence(memory_order_sync);
// Destroy any remaining objects in queue and free memory
Block* frontBlock_ = frontBlock;
Block* block = frontBlock_;
do {
Block* nextBlock = block->next;
size_t blockFront = block->front;
size_t blockTail = block->tail;
for (size_t i = blockFront; i != blockTail; i = (i + 1) & block->sizeMask) {
auto element = reinterpret_cast<T*>(block->data + i * sizeof(T));
element->~T();
(void)element;
}
auto rawBlock = block->rawThis;
block->~Block();
std::free(rawBlock);
block = nextBlock;
} while (block != frontBlock_);
}
// Enqueues a copy of element if there is room in the queue.
// Returns true if the element was enqueued, false otherwise.
// Does not allocate memory.
AE_FORCEINLINE bool try_enqueue(T const& element) AE_NO_TSAN
{
return inner_enqueue<CannotAlloc>(element);
}
// Enqueues a moved copy of element if there is room in the queue.
// Returns true if the element was enqueued, false otherwise.
// Does not allocate memory.
AE_FORCEINLINE bool try_enqueue(T&& element) AE_NO_TSAN
{
return inner_enqueue<CannotAlloc>(std::forward<T>(element));
}
#if MOODYCAMEL_HAS_EMPLACE
// Like try_enqueue() but with emplace semantics (i.e. construct-in-place).
template<typename... Args>
AE_FORCEINLINE bool try_emplace(Args&&... args) AE_NO_TSAN
{
return inner_enqueue<CannotAlloc>(std::forward<Args>(args)...);
}
#endif
// Enqueues a copy of element on the queue.
// Allocates an additional block of memory if needed.
// Only fails (returns false) if memory allocation fails.
AE_FORCEINLINE bool enqueue(T const& element) AE_NO_TSAN
{
return inner_enqueue<CanAlloc>(element);
}
// Enqueues a moved copy of element on the queue.
// Allocates an additional block of memory if needed.
// Only fails (returns false) if memory allocation fails.
AE_FORCEINLINE bool enqueue(T&& element) AE_NO_TSAN
{
return inner_enqueue<CanAlloc>(std::forward<T>(element));
}
#if MOODYCAMEL_HAS_EMPLACE
// Like enqueue() but with emplace semantics (i.e. construct-in-place).
template<typename... Args>
AE_FORCEINLINE bool emplace(Args&&... args) AE_NO_TSAN
{
return inner_enqueue<CanAlloc>(std::forward<Args>(args)...);
}
#endif
// Attempts to dequeue an element; if the queue is empty,
// returns false instead. If the queue has at least one element,
// moves front to result using operator=, then returns true.
template<typename U>
bool try_dequeue(U& result) AE_NO_TSAN
{
#ifndef NDEBUG
ReentrantGuard guard(this->dequeuing);
#endif
// High-level pseudocode:
// Remember where the tail block is
// If the front block has an element in it, dequeue it
// Else
// If front block was the tail block when we entered the function, return false
// Else advance to next block and dequeue the item there
// Note that we have to use the value of the tail block from before we check if the front
// block is full or not, in case the front block is empty and then, before we check if the
// tail block is at the front block or not, the producer fills up the front block *and
// moves on*, which would make us skip a filled block. Seems unlikely, but was consistently
// reproducible in practice.
// In order to avoid overhead in the common case, though, we do a double-checked pattern
// where we have the fast path if the front block is not empty, then read the tail block,
// then re-read the front block and check if it's not empty again, then check if the tail
// block has advanced.
Block* frontBlock_ = frontBlock.load();
size_t blockTail = frontBlock_->localTail;
size_t blockFront = frontBlock_->front.load();
if (blockFront != blockTail || blockFront != (frontBlock_->localTail = frontBlock_->tail.load())) {
fence(memory_order_acquire);
non_empty_front_block:
// Front block not empty, dequeue from here
auto element = reinterpret_cast<T*>(frontBlock_->data + blockFront * sizeof(T));
result = std::move(*element);
element->~T();
blockFront = (blockFront + 1) & frontBlock_->sizeMask;
fence(memory_order_release);
frontBlock_->front = blockFront;
}
else if (frontBlock_ != tailBlock.load()) {
fence(memory_order_acquire);
frontBlock_ = frontBlock.load();
blockTail = frontBlock_->localTail = frontBlock_->tail.load();
blockFront = frontBlock_->front.load();
fence(memory_order_acquire);
if (blockFront != blockTail) {
// Oh look, the front block isn't empty after all
goto non_empty_front_block;
}
// Front block is empty but there's another block ahead, advance to it
Block* nextBlock = frontBlock_->next;
// Don't need an acquire fence here since next can only ever be set on the tailBlock,
// and we're not the tailBlock, and we did an acquire earlier after reading tailBlock which
// ensures next is up-to-date on this CPU in case we recently were at tailBlock.
size_t nextBlockFront = nextBlock->front.load();
size_t nextBlockTail = nextBlock->localTail = nextBlock->tail.load();
fence(memory_order_acquire);
// Since the tailBlock is only ever advanced after being written to,
// we know there's for sure an element to dequeue on it
assert(nextBlockFront != nextBlockTail);
AE_UNUSED(nextBlockTail);
// We're done with this block, let the producer use it if it needs
fence(memory_order_release); // Expose possibly pending changes to frontBlock->front from last dequeue
frontBlock = frontBlock_ = nextBlock;
compiler_fence(memory_order_release); // Not strictly needed
auto element = reinterpret_cast<T*>(frontBlock_->data + nextBlockFront * sizeof(T));
result = std::move(*element);
element->~T();
nextBlockFront = (nextBlockFront + 1) & frontBlock_->sizeMask;
fence(memory_order_release);
frontBlock_->front = nextBlockFront;
}
else {
// No elements in current block and no other block to advance to
return false;
}
return true;
}
// Returns a pointer to the front element in the queue (the one that
// would be removed next by a call to `try_dequeue` or `pop`). If the
// queue appears empty at the time the method is called, nullptr is
// returned instead.
// Must be called only from the consumer thread.
T* peek() AE_NO_TSAN
{
#ifndef NDEBUG
ReentrantGuard guard(this->dequeuing);
#endif
// See try_dequeue() for reasoning
Block* frontBlock_ = frontBlock.load();
size_t blockTail = frontBlock_->localTail;
size_t blockFront = frontBlock_->front.load();
if (blockFront != blockTail || blockFront != (frontBlock_->localTail = frontBlock_->tail.load())) {
fence(memory_order_acquire);
non_empty_front_block:
return reinterpret_cast<T*>(frontBlock_->data + blockFront * sizeof(T));
}
else if (frontBlock_ != tailBlock.load()) {
fence(memory_order_acquire);
frontBlock_ = frontBlock.load();
blockTail = frontBlock_->localTail = frontBlock_->tail.load();
blockFront = frontBlock_->front.load();
fence(memory_order_acquire);
if (blockFront != blockTail) {
goto non_empty_front_block;
}
Block* nextBlock = frontBlock_->next;
size_t nextBlockFront = nextBlock->front.load();
fence(memory_order_acquire);
assert(nextBlockFront != nextBlock->tail.load());
return reinterpret_cast<T*>(nextBlock->data + nextBlockFront * sizeof(T));
}
return nullptr;
}
// Removes the front element from the queue, if any, without returning it.
// Returns true on success, or false if the queue appeared empty at the time
// `pop` was called.
bool pop() AE_NO_TSAN
{
#ifndef NDEBUG
ReentrantGuard guard(this->dequeuing);
#endif
// See try_dequeue() for reasoning
Block* frontBlock_ = frontBlock.load();
size_t blockTail = frontBlock_->localTail;
size_t blockFront = frontBlock_->front.load();
if (blockFront != blockTail || blockFront != (frontBlock_->localTail = frontBlock_->tail.load())) {
fence(memory_order_acquire);
non_empty_front_block:
auto element = reinterpret_cast<T*>(frontBlock_->data + blockFront * sizeof(T));
element->~T();
blockFront = (blockFront + 1) & frontBlock_->sizeMask;
fence(memory_order_release);
frontBlock_->front = blockFront;
}
else if (frontBlock_ != tailBlock.load()) {
fence(memory_order_acquire);
frontBlock_ = frontBlock.load();
blockTail = frontBlock_->localTail = frontBlock_->tail.load();
blockFront = frontBlock_->front.load();
fence(memory_order_acquire);
if (blockFront != blockTail) {
goto non_empty_front_block;
}
// Front block is empty but there's another block ahead, advance to it
Block* nextBlock = frontBlock_->next;
size_t nextBlockFront = nextBlock->front.load();
size_t nextBlockTail = nextBlock->localTail = nextBlock->tail.load();
fence(memory_order_acquire);
assert(nextBlockFront != nextBlockTail);
AE_UNUSED(nextBlockTail);
fence(memory_order_release);
frontBlock = frontBlock_ = nextBlock;
compiler_fence(memory_order_release);
auto element = reinterpret_cast<T*>(frontBlock_->data + nextBlockFront * sizeof(T));
element->~T();
nextBlockFront = (nextBlockFront + 1) & frontBlock_->sizeMask;
fence(memory_order_release);
frontBlock_->front = nextBlockFront;
}
else {
// No elements in current block and no other block to advance to
return false;
}
return true;
}
// Returns the approximate number of items currently in the queue.
// Safe to call from both the producer and consumer threads.
inline size_t size_approx() const AE_NO_TSAN
{
size_t result = 0;
Block* frontBlock_ = frontBlock.load();
Block* block = frontBlock_;
do {
fence(memory_order_acquire);
size_t blockFront = block->front.load();
size_t blockTail = block->tail.load();
result += (blockTail - blockFront) & block->sizeMask;
block = block->next.load();
} while (block != frontBlock_);
return result;
}
private:
enum AllocationMode { CanAlloc, CannotAlloc };
#if MOODYCAMEL_HAS_EMPLACE
template<AllocationMode canAlloc, typename... Args>
bool inner_enqueue(Args&&... args) AE_NO_TSAN
#else
template<AllocationMode canAlloc, typename U>
bool inner_enqueue(U&& element) AE_NO_TSAN
#endif
{
#ifndef NDEBUG
ReentrantGuard guard(this->enqueuing);
#endif
// High-level pseudocode (assuming we're allowed to alloc a new block):
// If room in tail block, add to tail
// Else check next block
// If next block is not the head block, enqueue on next block
// Else create a new block and enqueue there
// Advance tail to the block we just enqueued to
Block* tailBlock_ = tailBlock.load();
size_t blockFront = tailBlock_->localFront;
size_t blockTail = tailBlock_->tail.load();
size_t nextBlockTail = (blockTail + 1) & tailBlock_->sizeMask;
if (nextBlockTail != blockFront || nextBlockTail != (tailBlock_->localFront = tailBlock_->front.load())) {
fence(memory_order_acquire);
// This block has room for at least one more element
char* location = tailBlock_->data + blockTail * sizeof(T);
#if MOODYCAMEL_HAS_EMPLACE
new (location) T(std::forward<Args>(args)...);
#else
new (location) T(std::forward<U>(element));
#endif
fence(memory_order_release);
tailBlock_->tail = nextBlockTail;
}
else {
fence(memory_order_acquire);
if (tailBlock_->next.load() != frontBlock) {
// Note that the reason we can't advance to the frontBlock and start adding new entries there
// is because if we did, then dequeue would stay in that block, eventually reading the new values,
// instead of advancing to the next full block (whose values were enqueued first and so should be
// consumed first).
fence(memory_order_acquire); // Ensure we get latest writes if we got the latest frontBlock
// tailBlock is full, but there's a free block ahead, use it
Block* tailBlockNext = tailBlock_->next.load();
size_t nextBlockFront = tailBlockNext->localFront = tailBlockNext->front.load();
nextBlockTail = tailBlockNext->tail.load();
fence(memory_order_acquire);
// This block must be empty since it's not the head block and we
// go through the blocks in a circle
assert(nextBlockFront == nextBlockTail);
tailBlockNext->localFront = nextBlockFront;
char* location = tailBlockNext->data + nextBlockTail * sizeof(T);
#if MOODYCAMEL_HAS_EMPLACE
new (location) T(std::forward<Args>(args)...);
#else
new (location) T(std::forward<U>(element));
#endif
tailBlockNext->tail = (nextBlockTail + 1) & tailBlockNext->sizeMask;
fence(memory_order_release);
tailBlock = tailBlockNext;
}
else if (canAlloc == CanAlloc) {
// tailBlock is full and there's no free block ahead; create a new block
auto newBlockSize = largestBlockSize >= MAX_BLOCK_SIZE ? largestBlockSize : largestBlockSize * 2;
auto newBlock = make_block(newBlockSize);
if (newBlock == nullptr) {
// Could not allocate a block!
return false;
}
largestBlockSize = newBlockSize;
#if MOODYCAMEL_HAS_EMPLACE
new (newBlock->data) T(std::forward<Args>(args)...);
#else
new (newBlock->data) T(std::forward<U>(element));
#endif
assert(newBlock->front == 0);
newBlock->tail = newBlock->localTail = 1;
newBlock->next = tailBlock_->next.load();
tailBlock_->next = newBlock;
// Might be possible for the dequeue thread to see the new tailBlock->next
// *without* seeing the new tailBlock value, but this is OK since it can't
// advance to the next block until tailBlock is set anyway (because the only
// case where it could try to read the next is if it's already at the tailBlock,
// and it won't advance past tailBlock in any circumstance).
fence(memory_order_release);
tailBlock = newBlock;
}
else if (canAlloc == CannotAlloc) {
// Would have had to allocate a new block to enqueue, but not allowed
return false;
}
else {
assert(false && "Should be unreachable code");
return false;
}
}
return true;
}
// Disable copying
ReaderWriterQueue(ReaderWriterQueue const&) { }
// Disable assignment
ReaderWriterQueue& operator=(ReaderWriterQueue const&) { }
AE_FORCEINLINE static size_t ceilToPow2(size_t x)
{
// From http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
--x;
x |= x >> 1;
x |= x >> 2;
x |= x >> 4;
for (size_t i = 1; i < sizeof(size_t); i <<= 1) {
x |= x >> (i << 3);
}
++x;
return x;
}
template<typename U>
static AE_FORCEINLINE char* align_for(char* ptr) AE_NO_TSAN
{
const std::size_t alignment = std::alignment_of<U>::value;
return ptr + (alignment - (reinterpret_cast<std::uintptr_t>(ptr) % alignment)) % alignment;
}
private:
#ifndef NDEBUG
struct ReentrantGuard
{
AE_NO_TSAN ReentrantGuard(bool& _inSection)
: inSection(_inSection)
{
assert(!inSection && "Concurrent (or re-entrant) enqueue or dequeue operation detected (only one thread at a time may hold the producer or consumer role)");
inSection = true;
}
AE_NO_TSAN ~ReentrantGuard() { inSection = false; }
private:
ReentrantGuard& operator=(ReentrantGuard const&);
private:
bool& inSection;
};
#endif
struct Block
{
// Avoid false-sharing by putting highly contended variables on their own cache lines
weak_atomic<size_t> front; // (Atomic) Elements are read from here
size_t localTail; // An uncontended shadow copy of tail, owned by the consumer
char cachelineFiller0[MOODYCAMEL_CACHE_LINE_SIZE - sizeof(weak_atomic<size_t>) - sizeof(size_t)];
weak_atomic<size_t> tail; // (Atomic) Elements are enqueued here
size_t localFront;
char cachelineFiller1[MOODYCAMEL_CACHE_LINE_SIZE - sizeof(weak_atomic<size_t>) - sizeof(size_t)]; // next isn't very contended, but we don't want it on the same cache line as tail (which is)
weak_atomic<Block*> next; // (Atomic)
char* data; // Contents (on heap) are aligned to T's alignment
const size_t sizeMask;
// size must be a power of two (and greater than 0)
AE_NO_TSAN Block(size_t const& _size, char* _rawThis, char* _data)
: front(0), localTail(0), tail(0), localFront(0), next(nullptr), data(_data), sizeMask(_size - 1), rawThis(_rawThis)
{
}
private:
// C4512 - Assignment operator could not be generated
Block& operator=(Block const&);
public:
char* rawThis;
};
static Block* make_block(size_t capacity) AE_NO_TSAN
{
// Allocate enough memory for the block itself, as well as all the elements it will contain
auto size = sizeof(Block) + std::alignment_of<Block>::value - 1;
size += sizeof(T) * capacity + std::alignment_of<T>::value - 1;
auto newBlockRaw = static_cast<char*>(std::malloc(size));
if (newBlockRaw == nullptr) {
return nullptr;
}
auto newBlockAligned = align_for<Block>(newBlockRaw);
auto newBlockData = align_for<T>(newBlockAligned + sizeof(Block));
return new (newBlockAligned) Block(capacity, newBlockRaw, newBlockData);
}
private:
weak_atomic<Block*> frontBlock; // (Atomic) Elements are enqueued to this block
char cachelineFiller[MOODYCAMEL_CACHE_LINE_SIZE - sizeof(weak_atomic<Block*>)];
weak_atomic<Block*> tailBlock; // (Atomic) Elements are dequeued from this block
size_t largestBlockSize;
#ifndef NDEBUG
bool enqueuing;
bool dequeuing;
#endif
};
// Like ReaderWriterQueue, but also providees blocking operations
template<typename T, size_t MAX_BLOCK_SIZE = 512>
class BlockingReaderWriterQueue
{
private:
typedef ::moodycamel::ReaderWriterQueue<T, MAX_BLOCK_SIZE> ReaderWriterQueue;
public:
explicit BlockingReaderWriterQueue(size_t maxSize = 15) AE_NO_TSAN
: inner(maxSize), sema(new spsc_sema::LightweightSemaphore())
{ }
BlockingReaderWriterQueue(BlockingReaderWriterQueue&& other) AE_NO_TSAN
: inner(std::move(other.inner)), sema(std::move(other.sema))
{ }
BlockingReaderWriterQueue& operator=(BlockingReaderWriterQueue&& other) AE_NO_TSAN
{
std::swap(sema, other.sema);
std::swap(inner, other.inner);
return *this;
}
// Enqueues a copy of element if there is room in the queue.
// Returns true if the element was enqueued, false otherwise.
// Does not allocate memory.
AE_FORCEINLINE bool try_enqueue(T const& element) AE_NO_TSAN
{
if (inner.try_enqueue(element)) {
sema->signal();
return true;
}
return false;
}
// Enqueues a moved copy of element if there is room in the queue.
// Returns true if the element was enqueued, false otherwise.
// Does not allocate memory.
AE_FORCEINLINE bool try_enqueue(T&& element) AE_NO_TSAN
{
if (inner.try_enqueue(std::forward<T>(element))) {
sema->signal();
return true;
}
return false;
}
// Enqueues a copy of element on the queue.
// Allocates an additional block of memory if needed.
// Only fails (returns false) if memory allocation fails.
AE_FORCEINLINE bool enqueue(T const& element) AE_NO_TSAN
{
if (inner.enqueue(element)) {
sema->signal();
return true;
}
return false;
}
// Enqueues a moved copy of element on the queue.
// Allocates an additional block of memory if needed.
// Only fails (returns false) if memory allocation fails.
AE_FORCEINLINE bool enqueue(T&& element) AE_NO_TSAN
{
if (inner.enqueue(std::forward<T>(element))) {
sema->signal();
return true;
}
return false;
}
// Attempts to dequeue an element; if the queue is empty,
// returns false instead. If the queue has at least one element,
// moves front to result using operator=, then returns true.
template<typename U>
bool try_dequeue(U& result) AE_NO_TSAN
{
if (sema->tryWait()) {
bool success = inner.try_dequeue(result);
assert(success);
AE_UNUSED(success);
return true;
}
return false;
}
// Attempts to dequeue an element; if the queue is empty,
// waits until an element is available, then dequeues it.
template<typename U>
void wait_dequeue(U& result) AE_NO_TSAN
{
sema->wait();
bool success = inner.try_dequeue(result);
AE_UNUSED(result);
assert(success);
AE_UNUSED(success);
}
// Attempts to dequeue an element; if the queue is empty,
// waits until an element is available up to the specified timeout,
// then dequeues it and returns true, or returns false if the timeout
// expires before an element can be dequeued.
// Using a negative timeout indicates an indefinite timeout,
// and is thus functionally equivalent to calling wait_dequeue.
template<typename U>
bool wait_dequeue_timed(U& result, std::int64_t timeout_usecs) AE_NO_TSAN
{
if (!sema->wait(timeout_usecs)) {
return false;
}
bool success = inner.try_dequeue(result);
AE_UNUSED(result);
assert(success);
AE_UNUSED(success);
return true;
}
#if __cplusplus > 199711L || _MSC_VER >= 1700
// Attempts to dequeue an element; if the queue is empty,
// waits until an element is available up to the specified timeout,
// then dequeues it and returns true, or returns false if the timeout
// expires before an element can be dequeued.
// Using a negative timeout indicates an indefinite timeout,
// and is thus functionally equivalent to calling wait_dequeue.
template<typename U, typename Rep, typename Period>
inline bool wait_dequeue_timed(U& result, std::chrono::duration<Rep, Period> const& timeout) AE_NO_TSAN
{
return wait_dequeue_timed(result, std::chrono::duration_cast<std::chrono::microseconds>(timeout).count());
}
#endif
// Returns a pointer to the front element in the queue (the one that
// would be removed next by a call to `try_dequeue` or `pop`). If the
// queue appears empty at the time the method is called, nullptr is
// returned instead.
// Must be called only from the consumer thread.
AE_FORCEINLINE T* peek() AE_NO_TSAN
{
return inner.peek();
}
// Removes the front element from the queue, if any, without returning it.
// Returns true on success, or false if the queue appeared empty at the time
// `pop` was called.
AE_FORCEINLINE bool pop() AE_NO_TSAN
{
if (sema->tryWait()) {
bool result = inner.pop();
assert(result);
AE_UNUSED(result);
return true;
}
return false;
}
// Returns the approximate number of items currently in the queue.
// Safe to call from both the producer and consumer threads.
AE_FORCEINLINE size_t size_approx() const AE_NO_TSAN
{
return sema->availableApprox();
}
private:
// Disable copying & assignment
BlockingReaderWriterQueue(BlockingReaderWriterQueue const&) { }
BlockingReaderWriterQueue& operator=(BlockingReaderWriterQueue const&) { }
private:
ReaderWriterQueue inner;
std::unique_ptr<spsc_sema::LightweightSemaphore> sema;
};
} // end namespace moodycamel
#ifdef AE_VCPP
#pragma warning(pop)
#endif

73
piScan_backend/src/messages.h Normal file
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@ -0,0 +1,73 @@
/*
* messages.h
*
* Created on: Feb 10, 2019
* Author: ezra
*/
#ifndef MESSAGES_H_
#define MESSAGES_H_
#include "atomicops.h"
#include "concurrentqueue.h"
#include "readerwriterqueue.h"
enum {
MAIN_THREAD,
SCANNER_SM,
DEMOD,
SERVER_MAN,
AUDIO_MAN,
};
/* basic interthread message structure */
class Message {
public:
Message(unsigned char src, unsigned char dst, void* data) : source(src), destination(dst), pData(data) {}
const unsigned char source;
const unsigned char destination;
void* const pData;
};
class ScannerMessage : public Message {
public:
ScannerMessage(unsigned char src, unsigned char msgType, void* data) :
Message(src, SCANNER_SM, data), type(msgType) {}
const unsigned char type;
enum {
STATE_REQUEST = 0,
STOP = 0xFF
};
enum {
STATE_SCAN,
STATE_HOLD,
};
};
class DemodMessage : public Message {
};
class AudioMessage : public Message {
public:
AudioMessage(unsigned char src, unsigned char msgType, void* data) :
Message(src, AUDIO_MAN, data), type(msgType) {}
const unsigned char type;
enum {
ENABLE_OUTPUT = 0,
DISABLE_OUTPUT,
STOP = 0xFF
};
};
/* interface for all classes using ITC */
class MessageReceiver {
public:
virtual ~MessageReceiver();
virtual void giveMessage(Message msg) = 0;
};
#endif /* MESSAGES_H_ */

18
piScan_backend/src/server/Configuration.cpp Normal file
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@ -0,0 +1,18 @@
/*
* Configuration.cpp
*
* Created on: Feb 10, 2019
* Author: ezra
*/
#include "Configuration.h"
Configuration::Configuration() {
// TODO Auto-generated constructor stub
}
Configuration::~Configuration() {
// TODO Auto-generated destructor stub
}

29
piScan_backend/src/server/Configuration.h Normal file
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@ -0,0 +1,29 @@
/*
* Configuration.h
*
* Created on: Feb 10, 2019
* Author: ezra
*/
#ifndef SERVER_CONFIGURATION_H_
#define SERVER_CONFIGURATION_H_
class SocketServerConfig {
};
class LoggingConfig {
};
class DemodConfig {
};
class Configuration {
public:
Configuration();
~Configuration();
};
#endif /* SERVER_CONFIGURATION_H_ */

10
piScan_backend/src/server/ScannerStateMachine.cpp
View File

@ -26,7 +26,7 @@ ScannerStateMachine::ScannerStateMachine() :
void ScannerStateMachine::startScan(){
BEGIN_TRANSITION_MAP
TRANSITION_MAP_ENTRY(EVENT_IGNORED)
TRANSITION_MAP_ENTRY(ST_SCAN)
TRANSITION_MAP_ENTRY(EVENT_IGNORED)
TRANSITION_MAP_ENTRY(ST_SCAN)
TRANSITION_MAP_ENTRY(ST_SCAN)
@ -63,11 +63,11 @@ void ScannerStateMachine::stopScanner(){
void ScannerStateMachine::ST_Load(){
//file read and system tree population
InternalEvent(ST_SCAN);
// do not issue event - SM will wait until an event is generated before proceeding
//InternalEvent(ST_SCAN);
}
void ScannerStateMachine::ST_Scan(){
if(currentEntry->hasSignal()){
InternalEvent(ST_RECEIVE);
}
@ -82,6 +82,10 @@ void ScannerStateMachine::ST_Hold(){
}
void ScannerStateMachine::ST_Receive(){
/*
* -open audio stream
* -notify signal stats to listeners
*/
if (currentEntry->hasSignal()) {
InternalEvent(ST_RECEIVE);

4
piScan_backend/src/server/ScannerStateMachine.h
View File

@ -11,9 +11,10 @@
#include "StateMachine.h"
#include "SystemList.h"
#include "Entry.h"
#include "messages.h"
class ScannerStateMachine: public StateMachine {
class ScannerStateMachine: public MessageReceiver, StateMachine {
public:
ScannerStateMachine();
//~ScannerStateMachine();
@ -51,6 +52,7 @@ private:
};
private:
moodycamel::ReaderWriterQueue _msgQueue;
SystemList systems;
RadioSystem* currentSystem;
Entry* currentEntry;

27
piScan_backend/src/server/StateMachine.cpp
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@ -11,11 +11,21 @@
StateMachine::StateMachine(int maxStates) :
_maxStates(maxStates),
currentState(0),
lastState(0),
evtSrcExternal(false),
_eventGenerated(false),
_pEventData(NULL)
{
}
StateMachine::~StateMachine(){
_stateMachineThread.join();
}
void StateMachine::start() {
_stateMachineThread(StateThreadFunc);
}
// generates an external event. called once per external event
// to start the state machine executing
void StateMachine::ExternalEvent(unsigned char newState,
@ -28,9 +38,10 @@ void StateMachine::ExternalEvent(unsigned char newState,
delete pData;
}
else {
std::lock_guard<std::mutex> lock(_eventMutex);
// generate the event and execute the state engine
InternalEvent(newState, pData);
StateEngine();
//StateEngine();
}
}
@ -41,6 +52,7 @@ void StateMachine::InternalEvent(unsigned char newState,
{
_pEventData = pData;
_eventGenerated = true;
lastState = currentState;
currentState = newState;
}
@ -50,8 +62,10 @@ void StateMachine::StateEngine(void)
EventData* pDataTemp = NULL;
// TBD - lock semaphore here
std::lock_guard<std::mutex> lock(_eventMutex);
// while events are being generated keep executing states
while (_eventGenerated) {
if (_eventGenerated) {
pDataTemp = _pEventData; // copy of event data pointer
_pEventData = NULL; // event data used up, reset ptr
_eventGenerated = false; // event used up, reset flag
@ -71,3 +85,12 @@ void StateMachine::StateEngine(void)
// TBD - unlock semaphore here
}
void StateMachine::StateThreadFunc(void){
assert(currentState == 0);
//TODO add a break condition
while(1){
StateEngine();
}
}

8
piScan_backend/src/server/StateMachine.h
View File

@ -9,6 +9,8 @@
#define SERVER_STATEMACHINE_H_
#include <stdio.h>
#include <thread>
#include <mutex>
//#include "EventData.h"
class EventData
@ -25,9 +27,12 @@ class StateMachine
public:
StateMachine(int maxStates);
virtual ~StateMachine() {}
void start();
protected:
enum { EVENT_IGNORED = 0xFE, CANNOT_HAPPEN };
unsigned char currentState;
unsigned char lastState;
bool evtSrcExternal;
void ExternalEvent(unsigned char, EventData* = NULL);
void InternalEvent(unsigned char, EventData* = NULL);
virtual const StateStruct* GetStateMap() = 0;
@ -36,6 +41,9 @@ private:
bool _eventGenerated;
EventData* _pEventData;
void StateEngine(void);
void StateThreadFunc(void);
std::thread _stateMachineThread;
std::mutex _eventMutex;
};
typedef void (StateMachine::*StateFunc)(EventData *);

9
piScan_backend/src/server/StateMachine_test.cpp
View File

@ -1,9 +0,0 @@
/*
* StateMachine_test.cpp
*
* Created on: Feb 9, 2019
* Author: ezra
*/
#include "StateMachine.h"

18
piScan_backend/src/sigproc/Demodulator.cpp Normal file
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@ -0,0 +1,18 @@
/*
* Demodulator.cpp
*
* Created on: Feb 10, 2019
* Author: ezra
*/
#include "Demodulator.h"
Demodulator::Demodulator() {
// TODO Auto-generated constructor stub
}
Demodulator::~Demodulator() {
// TODO Auto-generated destructor stub
}

17
piScan_backend/src/sigproc/Demodulator.h Normal file
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@ -0,0 +1,17 @@
/*
* Demodulator.h
*
* Created on: Feb 10, 2019
* Author: ezra
*/
#ifndef SIGPROC_DEMODULATOR_H_
#define SIGPROC_DEMODULATOR_H_
class Demodulator {
public:
Demodulator();
~Demodulator();
};
#endif /* SIGPROC_DEMODULATOR_H_ */