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Fix terminate() of thread pool blocking if wait() is already called.

3 files changed, 51 insertions, 22 deletions

diff --git a/xsig/include/signature_db.hpp b/xsig/include/signature_db.hpp
index 107aa90..a74e90b 100644
--- a/xsig/include/signature_db.hpp
+++ b/xsig/include/signature_db.hpp
@@ -85,6 +85,7 @@ public:
     bool from_db_file(const fs::path &path);
 
     void populate(const std::vector<fs::path> &paths, const populate_cfg_t &cfg);
+    void populate_interrupt();
 
     //disjoint set for keeping similar images in the same group
     //some of these probably shouldn't be public. TBD...
diff --git a/xsig/src/signature_db.cpp b/xsig/src/signature_db.cpp
index ba1a372..6b328d6 100644
--- a/xsig/src/signature_db.cpp
+++ b/xsig/src/signature_db.cpp
@@ -28,6 +28,7 @@ struct signature_db_priv
     sqlite3 *db;
     sqlite3_mutex *mtx;
     sqlite3_stmt *bst[batch_status::BATCH_STATUS_MAX];
+    thread_pool *tp;
 
     void init_db();
     bool verify_db();
@@ -124,6 +125,8 @@ signature_db::signature_db(const fs::path &dbpath)
     p->mtx = sqlite3_db_mutex(p->db);
     for (int i = 0; i < batch_status::BATCH_STATUS_MAX; ++i)
         p->bst[i] = nullptr;
+    p->tp = nullptr;
+
     if (!p->verify_db())
     {
         sqlite3_close(p->db);
@@ -429,12 +432,19 @@ void signature_db::populate(const std::vector<fs::path> &paths, const populate_c
         cfg.callback(count.load(), thid);
     };
 
-    thread_pool tp(cfg.njobs);
+    p->tp = new thread_pool(cfg.njobs);
     for(size_t i = 0; i < paths.size(); ++i)
     {
-        tp.create_task(job_func, paths[i]);
+        p->tp->create_task(job_func, paths[i]);
     }
-    tp.wait();
+    p->tp->wait();
+    delete p->tp;
+    p->tp = nullptr;
+}
+void signature_db::populate_interrupt()
+{
+    if (p->tp)
+        p->tp->terminate();
 }
 
 void signature_db::ds_init()
diff --git a/xsig/src/thread_pool.hpp b/xsig/src/thread_pool.hpp
index 42b245a..de78721 100644
--- a/xsig/src/thread_pool.hpp
+++ b/xsig/src/thread_pool.hpp
@@ -24,7 +24,7 @@ public:
     bool pop(T&v)
     {
         std::unique_lock<std::mutex> lck(mtx);
-        if(!q.empty())
+        if (!q.empty())
         {
             v = std::move(q.front());
             q.pop();
@@ -49,23 +49,25 @@ public:
     {
         thr.resize(njobs);
         thstop.resize(njobs);
-        for(size_t i = 0; i < njobs; ++i)
+        for (size_t i = 0; i < njobs; ++i)
         {
             auto cstop = thstop[i] = std::make_shared<std::atomic<bool>>(false);
             auto looper = [this, i, cstop]
             {
-                std::atomic<bool>&stop = *cstop;
+                std::atomic<bool> &stop = *cstop;
                 std::function<void(int)> *f;
                 bool popped = wq.pop(f);
-                while(1)
+                while (1)
                 {
-                    for(; popped; popped = wq.pop(f))
+                    for (; popped; popped = wq.pop(f))
                     {
                         std::unique_ptr<std::function<void(int)>> pf(f);
                         (*f)(i);
-                        if(stop)return;
+                        if (stop.load()) return;
                     }
+
                     std::unique_lock<std::mutex> lck(mtx);
+
                     ++waiting_threads;
                     cv.wait(lck, [this, &f, &popped, &stop]
                     {
@@ -73,10 +75,11 @@ public:
                         return popped || wait_interrupt || stop;
                     });
                     --waiting_threads;
-                    if(!popped)return;
+                    if (!popped) return;
                 }
             };
             thr[i].reset(new std::thread(looper));
+            pthread_setname_np(thr[i]->native_handle(), (std::string("thrpool #") + std::to_string(i)).c_str());
         }
     }
     template<typename F, typename...A>
@@ -96,15 +99,20 @@ public:
     }
     void wait()
     {
-        if(!stop)
-            wait_interrupt = true;
+        if (!stop) wait_interrupt = true;
+
         {
             std::unique_lock<std::mutex> lck(mtx);
             cv.notify_all();
         }
-        for(size_t i = 0; i < thr.size(); ++i)if(thr[i]->joinable())thr[i]->join();
+        for (size_t i = 0; i < thr.size(); ++i)
+        {
+            if (thr[i]->joinable())
+                thr[i]->join();
+        }
+
         std::function<void(int)> *f = nullptr;
-        while(wq.size())
+        while (wq.size())
         {
             wq.pop(f);
             delete f;
@@ -116,24 +124,34 @@ public:
     {
         stop = true;
         std::function<void(int)> *f = nullptr;
-        while(wq.size())
+        while (wq.size())
         {
             wq.pop(f);
             delete f;
         }
-        for(size_t i = 0; i < thstop.size(); ++i)*thstop[i] = true;
+        for (size_t i = 0; i < thstop.size(); ++i)
+            *thstop[i] = true;
+
         {
             std::unique_lock<std::mutex> lck(mtx);
             cv.notify_all();
         }
-        for(size_t i = 0; i < thr.size(); ++i)if(thr[i]->joinable())thr[i]->join();
-        while(wq.size())
+        if (!wait_interrupt)
         {
-            wq.pop(f);
-            delete f;
+            for (size_t i = 0; i < thr.size(); ++i)
+            {
+                if (thr[i]->joinable())
+                    thr[i]->join();
+            }
+
+            while (wq.size())
+            {
+                wq.pop(f);
+                delete f;
+            }
+            thr.clear();
+            thstop.clear();
         }
-        thr.clear();
-        thstop.clear();
     }
 private:
     std::vector<std::unique_ptr<std::thread>> thr;