1、程序簡(jiǎn)介

該程序是基于OpenHarmony的C++公共基礎(chǔ)類庫(kù)的線程安全隊(duì)列：SafeQueue。

線程安全隊(duì)列，是在dequeue的基礎(chǔ)上封裝std::lock_guard，以此實(shí)現(xiàn)線程的相關(guān)操作。根據(jù)繼承SafeQueueInner抽象類，并對(duì)dequeue的pop方法的重寫(xiě)，可以實(shí)現(xiàn)SafeStack和SafeQueue的相關(guān)方法。

本案例主要完成如下工作：

創(chuàng)建2個(gè)子線程，1個(gè)線程負(fù)責(zé)入隊(duì)操作，1個(gè)線程負(fù)責(zé)出隊(duì)操作

子線程入隊(duì)操作，每1秒做1次入隊(duì)操作，循環(huán)5次

子線程入隊(duì)操作，每0.5秒做1次出隊(duì)操作，循環(huán)5次

該案例已在凌蒙派-RK3568開(kāi)發(fā)板驗(yàn)證過(guò)，如需要完整源代碼，請(qǐng)參考：

https://gitee.com/Lockzhiner-Electronics/lockzhiner-rk3568-openharmony/tree/master/samples/a27_utils_safequeue

2、基礎(chǔ)知識(shí)

C++公共基礎(chǔ)類庫(kù)為標(biāo)準(zhǔn)系統(tǒng)提供了一些常用的C++開(kāi)發(fā)工具類，包括：

文件、路徑、字符串相關(guān)操作的能力增強(qiáng)接口

讀寫(xiě)鎖、信號(hào)量、定時(shí)器、線程增強(qiáng)及線程池等接口

安全數(shù)據(jù)容器、數(shù)據(jù)序列化等接口

各子系統(tǒng)的錯(cuò)誤碼相關(guān)定義

2.1、添加C++公共基礎(chǔ)類庫(kù)依賴

修改需調(diào)用模塊的BUILD.gn，在external_deps或deps中添加如下：

ohos_shared_library("xxxxx") { ... external_deps = [ ... # 動(dòng)態(tài)庫(kù)依賴(可選) "c_utils:utils", # 靜態(tài)庫(kù)依賴(可選) "c_utils:utilsbase", # Rust動(dòng)態(tài)庫(kù)依賴(可選) "c_utils:utils_rust", ] ...}

一般而言，我們只需要填寫(xiě)"c_utils:utils"即可。

2.2、SafeQueue頭文件

C++公共基礎(chǔ)類庫(kù)的SafeQueue頭文件在：//commonlibrary/c_utils/base/include/safe_queue.h

可在源代碼中添加如下：

#include

2.3、OHOS::SafeQueueInner接口說(shuō)明

2.3.1、SafeQueueInner

構(gòu)造函數(shù)。

SafeQueueInner();

2.3.2、~SafeQueueInner()

析構(gòu)函數(shù)。

~SafeQueueInner();

2.3.3、Erase

移除某個(gè)元素。

void Erase(T& object);

參數(shù)說(shuō)明：

2.3.4、Empty

隊(duì)列判空。

bool Empty();

返回值說(shuō)明：

2.3.5、Clear

清空隊(duì)列元素。

void Clear();

2.3.6、Size

獲取隊(duì)列的容量。

int Size();

返回值說(shuō)明：

2.3.7、Push

入隊(duì)操作。

void Push(const T& pt);

參數(shù)說(shuō)明：

2.3.8、DoPush

Push底層調(diào)用DoPush，需要重寫(xiě)。

virtual void DoPush(const T& pt) = 0;

參數(shù)說(shuō)明：

2.3.9、Pop

出隊(duì)操作。

bool Pop(T& pt);

參數(shù)說(shuō)明：

返回值說(shuō)明：

2.3.10、DoPop

出隊(duì)操作。

virtual bool DoPop(T& pt) = 0;

參數(shù)說(shuō)明：

返回值說(shuō)明：

2.4、OHOS::SafeQueue接口說(shuō)明

SafeQueue繼承SafeQueueInner，實(shí)現(xiàn)DoPush()和DoPop()。

class SafeQueue : public SafeQueueInner

2.4.1、DoPush

入隊(duì)操作。

void DoPush(const T& pt);

參數(shù)說(shuō)明：

2.4.2、DoPop

出隊(duì)操作。

bool DoPop(T& pt);

參數(shù)說(shuō)明：

返回值說(shuō)明：

3、程序解析

3.1、創(chuàng)建編譯引導(dǎo)

在上一級(jí)目錄BUILD.gn文件添加一行編譯引導(dǎo)語(yǔ)句。

import("http://build/ohos.gni")
group("samples") { deps = [ "a27_utils_safequeue:utils_safequeue", # 添加該行 ]}

"a27_utils_safequeue:utils_safequeue",該行語(yǔ)句表示引入 參與編譯。

3.2、創(chuàng)建編譯項(xiàng)目

創(chuàng)建a27_utils_safequeue目錄，并添加如下文件：

a27_utils_safequeue├── utils_safequeue_sample.cppp # .cpp源代碼├──BUILD.gn#GN文件

3.3、創(chuàng)建BUILD.gn

編輯BUILD.gn文件。

import("http://build/ohos.gni")ohos_executable("utils_safequeue") { sources = [ "utils_safequeue_sample.cpp" ] include_dirs = [ "http://commonlibrary/c_utils/base/include", "http://commonlibrary/c_utils/base:utils", "http://third_party/googletest:gtest_main", "http://third_party/googletest/googletest/include" ] external_deps = [ "c_utils:utils" ] part_name = "product_rk3568" install_enable = true}

注意：

（1）BUILD.gn中所有的TAB鍵必須轉(zhuǎn)化為空格，否則會(huì)報(bào)錯(cuò)。如果自己不知道如何規(guī)范化，可以：

# 安裝gn工具sudo apt-get install ninja-buildsudo apt install generate-ninja# 規(guī)范化BUILD.gngn format BUILD.gn

3.4、創(chuàng)建源代碼

3.4.1、創(chuàng)建SafeMap

#include // SafeQueue的頭文件
// 定義隊(duì)列變量static OHOS::SafeQueue m_safeQueue;

3.4.2、創(chuàng)建線程池并設(shè)置

int main(int argc, char **argv){ OHOS::ThreadPool threads("threads"); string str_name; ...... threads.SetMaxTaskNum(128); threads.Start(2); ......}

3.4.3、啟動(dòng)2個(gè)子線程，并等待結(jié)束

調(diào)用AddTask()添加子線程，并調(diào)用Stop()等待所有子進(jìn)程結(jié)束。

// 開(kāi)啟子線程，使用Pushstr_name = "Thread_SafeQueue_Push";auto task_push = std::bind(funcSafeQueuePush, str_name);threads.AddTask(task_push);
// 開(kāi)啟子線程，使用Popstr_name = "Thread_SafeQueue_Pop";auto task_pop = std::bind(funcSafeQueuePop, str_name);threads.AddTask(task_pop);
// 設(shè)置結(jié)束，并等待結(jié)束threads.Stop();cout << "Threads Stop" << endl;

3.4.4、子線程入隊(duì)操作

static void funcSafeQueuePush(const string &name){ for (int i = 0; i < 5; i++) { // 入隊(duì)操作 cout << name << ", Push Start and i = " << i << endl; m_safeQueue.Push(i); cout << name << ", Push Successful and i = " << i << " and value = " << i << endl; // 睡眠1秒 cout << name << ", Sleep 1 sec" << endl; std::sleep_for(std::milliseconds(1000)); }}

3.4.5、子線程出隊(duì)操作

static void funcSafeQueuePop(const string &name){ bool ret; int value; for (int i = 0; i < 5; i++) { // 出隊(duì)操作 cout << name << ", Pop Start and i = " << i << endl; ret = m_safeQueue.Pop(value); cout << name << ", Pop Successful and i = " << i << " and ret = " << ret << " and value = " << value << endl; // 睡眠0.5秒 cout << name << ", Sleep 0.5 sec" << endl; std::sleep_for(std::milliseconds(500)); }
}

4、編譯步驟

進(jìn)入OpenHarmony編譯環(huán)境，運(yùn)行命令：

hb build -f

5、運(yùn)行結(jié)果

# utils_safequeueThread_SafeQueue_Push, Push Start and i = 0Thread_SafeQueue_Push, Push Successful and i = 0 and value = 0Thread_SafeQueue_Push, Sleep 1 secThread_SafeQueue_Pop, Pop Start and i = 0Thread_SafeQueue_Pop, Pop Successful and i = 0 and ret = 1 and value = 0Thread_SafeQueue_Pop, Sleep 0.5 secThread_SafeQueue_Pop, Pop Start and i = 1Thread_SafeQueue_Pop, Pop Successful and i = 1 and ret = 0 and value = 0Thread_SafeQueue_Pop, Sleep 0.5 secThread_SafeQueue_Push, Push Start and i = 1Thread_SafeQueue_Push, Push Successful and i = 1 and value = 1Thread_SafeQueue_Push, Sleep 1 secThread_SafeQueue_Pop, Pop Start and i = 2Thread_SafeQueue_Pop, Pop Successful and i = 2 and ret = 1 and value = 1Thread_SafeQueue_Pop, Sleep 0.5 secThread_SafeQueue_Pop, Pop Start and i = 3Thread_SafeQueue_Pop, Pop Successful and i = 3 and ret = 0 and value = 1Thread_SafeQueue_Pop, Sleep 0.5 secThread_SafeQueue_Push, Push Start and i = 2Thread_SafeQueue_Push, Push Successful and i = 2 and value = 2Thread_SafeQueue_Push, Sleep 1 secThread_SafeQueue_Pop, Pop Start and i = 4Thread_SafeQueue_Pop, Pop Successful and i = 4 and ret = 1 and value = 2Thread_SafeQueue_Pop, Sleep 0.5 secThread_SafeQueue_Push, Push Start and i = 3Thread_SafeQueue_Push, Push Successful and i = 3 and value = 3Thread_SafeQueue_Push, Sleep 1 secThread_SafeQueue_Push, Push Start and i = 4Thread_SafeQueue_Push, Push Successful and i = 4 and value = 4Thread_SafeQueue_Push, Sleep 1 secThreads Stop#