repeat HTTP requests once

src/ebusd/mainloop.cpp

@@ -379,8 +379,10 @@ void MainLoop::run() {
           m_busHandler->formatUpdateInfo(&ostr);
           ostr << "}";
           string response;
-          if (!m_httpClient.post("/", ostr.str(), &response)) {
+          bool repeat = false;
+          if (!m_httpClient.post("/", ostr.str(), &response, &repeat)) {
             logError(lf_main, "update check error: %s", response.c_str());
+            nextCheckRun = now + (repeat ? CHECK_INITIAL_DELAY : CHECK_DELAY);
           } else {
             m_updateCheck = response.empty() ? "unknown" : response;
             logNotice(lf_main, "update check: %s", response.c_str());
@@ -389,8 +391,8 @@ void MainLoop::run() {
                 dataSink->notifyUpdateCheckResult(response == "OK" ? "" : m_updateCheck);
               }
             }
+            nextCheckRun = now + CHECK_DELAY;
           }
-          nextCheckRun = now + CHECK_DELAY;
         }
       }
       time(&lastTaskRun);

src/ebusd/scan.cpp

@@ -57,6 +57,9 @@ ScanHelper::~ScanHelper() {
   }
 }
 
+// the time slice to sleep when repeating an HTTP request
+#define REPEAT_NANOS 1000000
+
 result_t ScanHelper::collectConfigFiles(const string& relPath, const string& prefix, const string& extension,
     vector<string>* files,
     bool ignoreAddressPrefix, const string& query,
@@ -66,8 +69,19 @@ result_t ScanHelper::collectConfigFiles(const string& relPath, const string& pre
     string uri = m_configUriPrefix + relPathWithSlash + m_configLangQuery + (m_configLangQuery.empty() ? "?" : "&")
       + "t=" + extension.substr(1) + query;
     string names;
-    if (!m_configHttpClient->get(uri, "", &names)) {
-      return RESULT_ERR_NOTFOUND;
+    bool repeat = false;
+    if (!m_configHttpClient->get(uri, "", &names, &repeat)) {
+      if (!names.empty()) {
+        logError(lf_main, "HTTP failure%s: %s", repeat ? ", repeating" : "", names.c_str());
+        names = "";
+      }
+      if (!repeat) {
+        return RESULT_ERR_NOTFOUND;
+      }
+      usleep(REPEAT_NANOS);
+      if (!m_configHttpClient->get(uri, "", &names)) {
+        return RESULT_ERR_NOTFOUND;
+      }
     }
     istringstream stream(names);
     string name;
@@ -261,11 +275,23 @@ result_t ScanHelper::loadDefinitionsFromConfigPath(FileReader* reader, const str
   time_t mtime = 0;
   if (m_configUriPrefix.empty()) {
     stream = FileReader::openFile(m_configLocalPrefix + filename, errorDescription, &mtime);
-  } else {
+  } else if (m_configHttpClient) {
+    string uri = m_configUriPrefix + filename + m_configLangQuery;
     string content;
-    if (m_configHttpClient
-    && m_configHttpClient->get(m_configUriPrefix + filename + m_configLangQuery, "", &content, &mtime)) {
+    bool repeat = false;
+    if (m_configHttpClient->get(uri, "", &content, &repeat, &mtime)) {
       stream = new istringstream(content);
+    } else {
+      if (!content.empty()) {
+        logError(lf_main, "HTTP failure%s: %s", repeat ? ", repeating" : "", content.c_str());
+        content = "";
+      }
+      if (repeat) {
+        usleep(REPEAT_NANOS);
+        if (m_configHttpClient->get(uri, "", &content, nullptr, &mtime)) {
+          stream = new istringstream(content);
+        }
+      }
     }
   }
   result_t result;

src/lib/utils/httpclient.cpp

@@ -431,12 +431,12 @@ void HttpClient::disconnect() {
   }
 }
 
-bool HttpClient::get(const string& uri, const string& body, string* response, time_t* time) {
-  return request("GET", uri, body, response, time);
+bool HttpClient::get(const string& uri, const string& body, string* response, bool* repeatable, time_t* time) {
+  return request("GET", uri, body, response, repeatable, time);
 }
 
-bool HttpClient::post(const string& uri, const string& body, string* response) {
-  return request("POST", uri, body, response);
+bool HttpClient::post(const string& uri, const string& body, string* response, bool* repeatable) {
+  return request("POST", uri, body, response, repeatable);
 }
 
 const int indexToMonth[] = {
@@ -446,9 +446,13 @@ const int indexToMonth[] = {
   -1, -1,  4, -1, -1, -1, -1, -1,  // 24-31
 };
 
-bool HttpClient::request(const string& method, const string& uri, const string& body, string* response, time_t* time) {
+bool HttpClient::request(const string& method, const string& uri, const string& body, string* response,
+bool* repeatable, time_t* time) {
   if (!ensureConnected()) {
     *response = "not connected";
+    if (repeatable) {
+      *repeatable = true;
+    }
     return false;
   }
   ostringstream ostr;
@@ -473,6 +477,9 @@ bool HttpClient::request(const string& method, const string& uri, const string&
     if (sent < 0) {
       disconnect();
       *response = "send error";
+      if (repeatable) {
+        *repeatable = true;
+      }
       return false;
     }
     pos += sent;

src/lib/utils/httpclient.h

@@ -188,19 +188,24 @@ class HttpClient {
    * @param uri the URI string.
    * @param body the optional body to send.
    * @param response the response body from the server (or the HTTP header on error).
+   * @param repeatable optional pointer to a bool in which to store whether the request should be repeated later on
+   * (e.g. due to temporary connectivity issues).
    * @param time optional pointer to a @a time_t value for storing the modification time of the file, or nullptr.
    * @return true on success, false on error.
    */
-  bool get(const string& uri, const string& body, string* response, time_t* time = nullptr);
+  bool get(const string& uri, const string& body, string* response, bool* repeatable = nullptr,
+  time_t* time = nullptr);
 
   /**
    * Execute a POST request.
    * @param uri the URI string.
    * @param body the optional body to send.
    * @param response the response body from the server (or the HTTP header on error).
+   * @param repeatable optional pointer to a bool in which to store whether the request should be repeated later on
+   * (e.g. due to temporary connectivity issues).
    * @return true on success, false on error.
    */
-  bool post(const string& uri, const string& body, string* response);
+  bool post(const string& uri, const string& body, string* response, bool* repeatable = nullptr);
 
   /**
    * Execute an arbitrary request.
@@ -208,10 +213,13 @@ class HttpClient {
    * @param uri the URI string.
    * @param body the optional body to send.
    * @param response the response body from the server (or the HTTP header on error).
+   * @param repeatable optional pointer to a bool in which to store whether the request should be repeated later on
+   * (e.g. due to temporary connectivity issues).
    * @param time optional pointer to a @a time_t value for storing the modification time of the file, or nullptr.
    * @return true on success, false on error.
    */
-  bool request(const string& method, const string& uri, const string& body, string* response, time_t* time = nullptr);
+  bool request(const string& method, const string& uri, const string& body, string* response,
+  bool* repeatable = nullptr, time_t* time = nullptr);
 
  private:
   /**