Merge pull request 'Replace multi-process logic to multi-thread logic' (#2) from process-to-threads into main

Reviewed-on: #2

configs/ncsambawatcher.service

@@ -1,6 +1,7 @@
 [Unit]
 Description=A service which scan Nextcloud folders
-After=network.target
+After=network.target docker.service
+Requires=docker.service
 
 [Service]
 ExecStart=/usr/bin/ncsambawatcher

src/guarder.h

@@ -4,20 +4,33 @@
 #include <sys/types.h>
 #include <sys/shm.h>
 #include <sys/ipc.h>
+#include <sys/sem.h>
+#include <unistd.h>
 
 class guarder{
 private:
     const int shmid;
+    const int semid;
+
+    void semaphoreOp(int op) {
+        struct sembuf sb{};
+        sb.sem_num = 0;
+        sb.sem_op = op;
+        sb.sem_flg = 0;
+        semop(semid, &sb, 1);
+    }
 
     void setFlag(bool value)
     {
+        semaphoreOp(-1);
         bool *flag = static_cast<bool *>(shmat(shmid, nullptr, 0));
         *flag = value;
         shmdt(flag);
+        semaphoreOp(1);
     }
 
 public:
-    guarder() : shmid(shmget(IPC_PRIVATE, sizeof(bool), 0666 | IPC_CREAT))
+    guarder() : shmid(shmget(IPC_PRIVATE, sizeof(bool), 0666 | IPC_CREAT)), semid(semget(IPC_PRIVATE, 1, 0666 | IPC_CREAT))
     {
         setFlagOff();
     }
@@ -34,15 +47,18 @@ public:
 
     bool isFlagOn()
     {
+        semaphoreOp(-1);
         bool *flag = static_cast<bool *>(shmat(shmid, nullptr, 0));
         bool ret = *flag;
         shmdt(flag);
+        semaphoreOp(1);
         return ret;
     }
 
     ~guarder()
     {
         shmctl(shmid, IPC_RMID, nullptr);
+        semctl(semid, 0, IPC_RMID);
     }
 
 };

src/main.cpp

@@ -1,119 +1,102 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/wait.h>
 #include <iostream>
+#include <thread>
+#include <vector>
+#include <set>
 #include <array>
 #include <string>
-#include <vector>
-#include <unistd.h>
-#include <sys/types.h>
-#include <syslog.h>
-#include <fcntl.h>
-#include <signal.h>
-#include "locations.h"
+#include <mutex>
+#include <condition_variable>
+#include <cstdio>
 #include "usermanager.h"
-#include "guarder.h"
 
-#define MAXNAMESIZE 255
-#define SCAN_DONE_SIG SIGRTMIN
 #define SCAN_CMD_USR "docker exec --user www-data nextcloud /var/www/html/occ files:scan --path="
 
-int p1[2];
-guarder guard;
 userManager manager;
+std::condition_variable cv;
+std::mutex mtx;
 
-void flushManagerToPipe()
+void readingThreadFunc()
 {
-    if (!guard.isFlagOn())
-    {
-        std::vector<std::string> users = manager.getFlaggedUsers();
+    FILE *logpipe = popen(LOGFILE, "r");
+    std::array<char, 256> buffer;
+
+    while (fgets(buffer.data(), buffer.size(), logpipe) != nullptr)
+    {
+        std::string line(buffer.data());
+
+        if (line.find('|') == std::string::npos)
+            continue;
+
+        std::vector<std::string> x = splitLogFile(line, '|');
+        std::string user(x.at(USER_LOG_LOCATION));
 
-        for (std::vector<std::string>::iterator it = users.begin(); it != users.end(); ++it)
         {
-            int size = it->size();
-            write(p1[1], &size, sizeof(int));
-            write(p1[1], it->data(), size * sizeof(char));
+            std::lock_guard<std::mutex> lock(mtx);
+            manager.addUser(user);
+            manager.setUserFlagged(user);
         }
 
-        manager.unflagAllUsers();
+        cv.notify_one();
+
+        std::cout << "User find: " << user << std::endl;
     }
 }
 
-void handler(int sig) 
+void scannerThreadFunc()
 {
-    if (sig == SCAN_DONE_SIG)
+    std::unique_lock<std::mutex> lock(mtx);
+    std::vector<pid_t> childrens;
+    while (true)
     {
-        flushManagerToPipe();
+        cv.wait(lock, []
+                { return manager.isAnybodyFlagged(); });
+
+        std::set<std::string> scanUsers = manager.getFlaggedUsers();
+        manager.unflagAllUsers();
+
+        lock.unlock();
+        childrens.clear();
+
+        for (const std::string& user : scanUsers)
+        {
+            pid_t child = fork();
+
+            if (child < 0)
+            {
+                std::cerr << "Fork failed for: " << user << std::endl;
+            }
+            else if (child == 0) // child
+            {
+                std::string cmd = (std::string(SCAN_CMD_USR) + user);
+                execl("/bin/sh", "sh", "-c", cmd.c_str(), static_cast<char *>(nullptr));
+                std::cerr << "Scan failed" << std::endl;
+                _exit(EXIT_FAILURE);
+            }
+            else // parent
+            {
+                childrens.push_back(child);
+            }
+        }
+
+        for (const pid_t& pid : childrens)
+        {
+            waitpid(pid, nullptr, 0);
+        }
+
+        lock.lock();
     }
 }
 
 int main()
 {
-    openlog("ncsambawatcher", LOG_PID | LOG_CONS, LOG_USER);
-    pipe(p1);
+    std::thread readingThread(readingThreadFunc);
+    std::thread scannerThread(scannerThreadFunc);
 
-    pid_t parent = getpid();
-    pid_t child = fork();
+    readingThread.join();
+    scannerThread.join();
 
-    if (child > 0) // parent
-    {
-        signal(SCAN_DONE_SIG, handler);
-        close(p1[0]); // read
-
-        FILE *logpipe = popen(LOGFILE, "r");
-        std::array<char, 256> buffer;
-
-        while (fgets(buffer.data(), buffer.size(), logpipe) != nullptr)
-        {
-            std::string line(buffer.data());
-
-            if (line.find('|') == std::string::npos)
-                continue;
-
-            std::vector<std::string> x = splitLogFile(line, '|');
-            std::string user(x.at(USER_LOG_LOCATION));
-            manager.addUser(user);
-            manager.setUserFlagged(user);
-
-            std::cout << "User find: " << user << std::endl;
-
-            flushManagerToPipe();
-        }
-
-        fclose(logpipe);
-        close(p1[1]); // write
-    }
-    else // child
-    {
-        close(p1[1]); // write
-
-        int size;
-        char *buffer = nullptr;
-
-        while (read(p1[0], &size, sizeof(int)))
-        {
-            if (buffer == nullptr)
-                buffer = new char[size];
-
-            read(p1[0], buffer, size * sizeof(char));
-            std::string name(buffer);
-
-            std::cout << "Scan received for: " << name << std::endl;
-
-            guard.setFlagOn();
-            system((std::string(SCAN_CMD_USR) + name).data());
-            guard.setFlagOff();
-
-            kill(parent, SCAN_DONE_SIG);
-
-            if (buffer != nullptr)
-            {
-                delete[] buffer;
-                buffer = nullptr;
-            }
-        }
-
-        close(p1[0]); // read
-    }
-
-    closelog();
-
-    return EXIT_SUCCESS;
+    return 0;
 }

src/usermanager.h

@@ -4,7 +4,9 @@
 #include <string>
 #include <map>
 #include <vector>
+#include <set>
 #include <sstream>
+#include <mutex>
 #include "locations.h"
 
 std::vector<std::string> splitLogFile(const std::string& input, char delimiter);
@@ -13,6 +15,7 @@ class userManager
 {
 private:
     std::map<std::string, bool> users;
+    std::mutex mtx;
 
 public:
     
@@ -23,6 +26,7 @@ public:
 
     void addUser(std::string &user)
     {
+        std::lock_guard<std::mutex> lock(mtx);
         if (users.count(user) == 0)
         {
             users[user] = false;
@@ -31,16 +35,19 @@ public:
 
     void removeUser(std::string &user)
     {
+        std::lock_guard<std::mutex> lock(mtx);
         users.erase(user);
     }
 
     bool isContains(std::string &user)
     {
+        std::lock_guard<std::mutex> lock(mtx);
         return users.count(user) == 1;
     }
 
     void setUserFlagged(std::string &user)
     {
+        std::lock_guard<std::mutex> lock(mtx);
         if (users.count(user) == 1)
         {
             users[user] = true;
@@ -49,6 +56,7 @@ public:
 
     void setUserUnflagged(std::string &user)
     {
+        std::lock_guard<std::mutex> lock(mtx);
         if (users.count(user) == 1)
         {
             users[user] = false;
@@ -57,38 +65,56 @@ public:
 
     void unflagAllUsers()
     {
+        std::lock_guard<std::mutex> lock(mtx);
         for (std::map<std::string, bool>::iterator it = users.begin(); it != users.end(); ++it)
         {
             it->second = false;
         }
     }
 
-    std::vector<std::string> getUsers()
+    std::set<std::string> getUsers()
     {
-        std::vector<std::string> ret;
+        std::set<std::string> ret;
+
+        std::lock_guard<std::mutex> lock(mtx);
 
         for (std::map<std::string, bool>::iterator it = users.begin(); it != users.end(); ++it)
         {
-            ret.push_back(it->first);
+            ret.insert(it->first);
         }
 
         return ret;
     }
 
-    std::vector<std::string> getFlaggedUsers()
+    std::set<std::string> getFlaggedUsers()
     {
-        std::vector<std::string> ret;
+        std::set<std::string> ret;
+
+        std::lock_guard<std::mutex> lock(mtx);
 
         for (std::map<std::string, bool>::iterator it = users.begin(); it != users.end(); ++it)
         {
             if (it->second)
             {
-                ret.push_back(it->first);
+                ret.insert(it->first);
             }
         }
 
         return ret;
     }
+
+    bool isAnybodyFlagged()
+    {
+        std::lock_guard<std::mutex> lock(mtx);
+    
+        for (std::map<std::string, bool>::iterator it = users.begin(); it != users.end(); ++it)
+        {
+            if (it->second)
+                return true;
+        }
+
+        return false;
+    }
 };
 
 #endif // _USERMAN_H