download: async API

src/common/download.cpp

@@ -40,27 +40,70 @@
 
 namespace tools
 {
-  static bool download_thread(const std::string &path, const std::string &url)
+  struct download_thread_control
   {
+    const std::string path;
+    const std::string uri;
+    std::function<void(const std::string&, const std::string&, bool)> result_cb;
+    std::function<bool(const std::string&, const std::string&, size_t, ssize_t)> progress_cb;
+    bool stop;
+    bool stopped;
+    bool success;
+    boost::thread thread;
+    boost::mutex mutex;
+
+    download_thread_control(const std::string &path, const std::string &uri, std::function<void(const std::string&, const std::string&, bool)> result_cb, std::function<bool(const std::string&, const std::string&, size_t, ssize_t)> progress_cb):
+        path(path), uri(uri), result_cb(result_cb), progress_cb(progress_cb), stop(false), stopped(false), success(false) {}
+    ~download_thread_control() { if (thread.joinable()) thread.detach(); }
+  };
+
+  static void download_thread(download_async_handle control)
+  {
+    struct stopped_setter
+    {
+      stopped_setter(const download_async_handle &control): control(control) {}
+      ~stopped_setter() { control->stopped = true; }
+      download_async_handle control;
+    } stopped_setter(control);
+
     try
     {
-      MINFO("Downloading " << url << " to " << path);
+      boost::unique_lock<boost::mutex> lock(control->mutex);
+      MINFO("Downloading " << control->uri << " to " << control->path);
       std::ofstream f;
-      f.open(path, std::ios_base::binary | std::ios_base::out | std::ios_base::trunc);
+      f.open(control->path, std::ios_base::binary | std::ios_base::out | std::ios_base::trunc);
       if (!f.good()) {
-        MERROR("Failed to open file " << path);
+        MERROR("Failed to open file " << control->path);
-        return false;
+        control->result_cb(control->path, control->uri, control->success);
+        return;
       }
       class download_client: public epee::net_utils::http::http_simple_client
       {
       public:
-        download_client(std::ofstream &f): f(f) {}
+        download_client(download_async_handle control, std::ofstream &f):
+          control(control), f(f), content_length(-1), total(0) {}
         virtual ~download_client() { f.close(); }
+        virtual bool on_header(const epee::net_utils::http::http_response_info &headers)
+        {
+          ssize_t length;
+          if (epee::string_tools::get_xtype_from_string(length, headers.m_header_info.m_content_length) && length >= 0)
+          {
+            MINFO("Content-Length: " << length);
+            content_length = length;
+          }
+          return true;
+        }
         virtual bool handle_target_data(std::string &piece_of_transfer)
         {
           try
           {
+            boost::lock_guard<boost::mutex> lock(control->mutex);
+            if (control->stop)
+              return false;
             f << piece_of_transfer;
+            total += piece_of_transfer.size();
+            if (control->progress_cb && !control->progress_cb(control->path, control->uri, total, content_length))
+              return false;
             return f.good();
           }
           catch (const std::exception &e)
@@ -70,69 +113,145 @@ namespace tools
           }
         }
       private:
+        download_async_handle control;
         std::ofstream &f;
-      } client(f);
+        ssize_t content_length;
+        size_t total;
+      } client(control, f);
       epee::net_utils::http::url_content u_c;
-      if (!epee::net_utils::parse_url(url, u_c))
+      if (!epee::net_utils::parse_url(control->uri, u_c))
       {
-        MWARNING("Failed to parse URL " << url);
+        MERROR("Failed to parse URL " << control->uri);
-        return false;
+        control->result_cb(control->path, control->uri, control->success);
+        return;
       }
       if (u_c.host.empty())
       {
-        MWARNING("Failed to determine address from URL " << url);
+        MERROR("Failed to determine address from URL " << control->uri);
-        return false;
+        control->result_cb(control->path, control->uri, control->success);
+        return;
       }
+
+      lock.unlock();
+
       uint16_t port = u_c.port ? u_c.port : 80;
       MDEBUG("Connecting to " << u_c.host << ":" << port);
       client.set_server(u_c.host, std::to_string(port), boost::none);
       if (!client.connect(std::chrono::seconds(30)))
       {
-        MERROR("Failed to connect to " << url);
+        boost::lock_guard<boost::mutex> lock(control->mutex);
-        return false;
+        MERROR("Failed to connect to " << control->uri);
+        control->result_cb(control->path, control->uri, control->success);
+        return;
       }
       MDEBUG("GETting " << u_c.uri);
       const epee::net_utils::http::http_response_info *info = NULL;
       if (!client.invoke_get(u_c.uri, std::chrono::seconds(30), "", &info))
       {
-        MERROR("Failed to connect to " << url);
+        boost::lock_guard<boost::mutex> lock(control->mutex);
+        MERROR("Failed to connect to " << control->uri);
         client.disconnect();
-        return false;
+        control->result_cb(control->path, control->uri, control->success);
+        return;
+      }
+      if (control->stop)
+      {
+        boost::lock_guard<boost::mutex> lock(control->mutex);
+        MDEBUG("Download cancelled");
+        client.disconnect();
+        control->result_cb(control->path, control->uri, control->success);
+        return;
       }
       if (!info)
       {
-        MERROR("Failed invoking GET command to " << url << ", no status info returned");
+        boost::lock_guard<boost::mutex> lock(control->mutex);
+        MERROR("Failed invoking GET command to " << control->uri << ", no status info returned");
         client.disconnect();
-        return false;
+        control->result_cb(control->path, control->uri, control->success);
+        return;
       }
       MDEBUG("response code: " << info->m_response_code);
+      MDEBUG("response length: " << info->m_header_info.m_content_length);
       MDEBUG("response comment: " << info->m_response_comment);
       MDEBUG("response body: " << info->m_body);
       for (const auto &f: info->m_additional_fields)
         MDEBUG("additional field: " << f.first << ": " << f.second);
       if (info->m_response_code != 200)
       {
+        boost::lock_guard<boost::mutex> lock(control->mutex);
         MERROR("Status code " << info->m_response_code);
         client.disconnect();
-        return false;
+        control->result_cb(control->path, control->uri, control->success);
+        return;
       }
       client.disconnect();
       f.close();
       MDEBUG("Download complete");
-      return true;
+      lock.lock();
+      control->success = true;
+      control->result_cb(control->path, control->uri, control->success);
+      return;
     }
     catch (const std::exception &e)
     {
       MERROR("Exception in download thread: " << e.what());
-      return false;
+      // fall through and call result_cb not from the catch block to avoid another exception
     }
+    boost::lock_guard<boost::mutex> lock(control->mutex);
+    control->result_cb(control->path, control->uri, control->success);
   }
 
-  bool download(const std::string &path, const std::string &url)
+  bool download(const std::string &path, const std::string &url, std::function<bool(const std::string&, const std::string&, size_t, ssize_t)> cb)
   {
-    bool success;
+    bool success = false;
-    std::unique_ptr<boost::thread> thread(new boost::thread([&](){ success = download_thread(path, url); }));
+    download_async_handle handle = download_async(path, url, [&success](const std::string&, const std::string&, bool result) {success = result;}, cb);
-    thread->join();
+    download_wait(handle);
     return success;
   }
+
+  download_async_handle download_async(const std::string &path, const std::string &url, std::function<void(const std::string&, const std::string&, bool)> result, std::function<bool(const std::string&, const std::string&, size_t, ssize_t)> progress)
+  {
+    download_async_handle control = std::make_shared<download_thread_control>(path, url, result, progress);
+    control->thread = boost::thread([control](){ download_thread(control); });
+    return control;
+  }
+
+  bool download_finished(const download_async_handle &control)
+  {
+    CHECK_AND_ASSERT_MES(control != 0, false, "NULL async download handle");
+    boost::lock_guard<boost::mutex> lock(control->mutex);
+    return control->stopped;
+  }
+
+  bool download_error(const download_async_handle &control)
+  {
+    CHECK_AND_ASSERT_MES(control != 0, false, "NULL async download handle");
+    boost::lock_guard<boost::mutex> lock(control->mutex);
+    return !control->success;
+  }
+
+  bool download_wait(const download_async_handle &control)
+  {
+    CHECK_AND_ASSERT_MES(control != 0, false, "NULL async download handle");
+    {
+      boost::lock_guard<boost::mutex> lock(control->mutex);
+      if (control->stopped)
+        return true;
+    }
+    control->thread.join();
+    return true;
+  }
+
+  bool download_cancel(const download_async_handle &control)
+  {
+    CHECK_AND_ASSERT_MES(control != 0, false, "NULL async download handle");
+    {
+      boost::lock_guard<boost::mutex> lock(control->mutex);
+      if (control->stopped)
+        return true;
+      control->stop = true;
+    }
+    control->thread.join();
+    return true;
+  }
 }

src/common/download.h

@@ -32,5 +32,13 @@
 
 namespace tools
 {
-  bool download(const std::string &path, const std::string &url);
+  struct download_thread_control;
+  typedef std::shared_ptr<download_thread_control> download_async_handle;
+
+  bool download(const std::string &path, const std::string &url, std::function<bool(const std::string&, const std::string&, size_t, ssize_t)> progress = NULL);
+  download_async_handle download_async(const std::string &path, const std::string &url, std::function<void(const std::string&, const std::string&, bool)> result, std::function<bool(const std::string&, const std::string&, size_t, ssize_t)> progress = NULL);
+  bool download_error(const download_async_handle &h);
+  bool download_finished(const download_async_handle &h);
+  bool download_wait(const download_async_handle &h);
+  bool download_cancel(const download_async_handle &h);
 }