Moved the function for finding host's FQDN(s) into util/

Extended the contract and the implementation of the function to
allow a choice to return a single result or all findings.
Migrated the only client of that function that existed before
the move.

src/replica/Registry.cc

@@ -26,21 +26,16 @@
 #include "replica/Configuration.h"
 #include "replica/ConfigWorker.h"
 #include "replica/HttpClient.h"
+#include "util/common.h"
 
 // LSST headers
 #include "lsst/log/Log.h"
 
 // Standard headers
-#include <netdb.h>
 #include <stdexcept>
 #include <string.h>
-#include <sys/types.h>
-#include <sys/socket.h>
 #include <thread>
 
-// Third-party headers
-#include "boost/asio.hpp"
-
 using namespace std;
 using json = nlohmann::json;
 
@@ -50,49 +45,6 @@ LOG_LOGGER _log = LOG_GET("lsst.qserv.replica.Registry");
 
 string context(string const& func) { return "REGISTRY " + func + " "; }
 
-/**
- * @brief Get the FQDN of the current host.
- * @note If there will be more than one canonical name associated with the host
- *   then  the result will contain them all separated by comma, such as in:
- * @code
- *   <fqdn-1>,<fqdn-2>,...
- * @endcode
- * @return The FQDN (or FQDNs)
- * @throws std::runtime_error In case if the information couldn't be retreived.
- */
-string get_current_host_fqdn() {
-    // Get the short name of the current host first.
-    boost::system::error_code ec;
-    string const hostname = boost::asio::ip::host_name(ec);
-    if (ec.value() != 0) {
-        throw runtime_error("Registry::" + string(__func__) +
-                            " boost::asio::ip::host_name failed: " + ec.category().name() + string(":") +
-                            to_string(ec.value()) + "[" + ec.message() + "]");
-    }
-
-    // Get the host's FQDN(s)
-    struct addrinfo hints;
-    memset(&hints, 0, sizeof hints);
-    hints.ai_family = AF_UNSPEC;     /* either IPV4 or IPV6 */
-    hints.ai_socktype = SOCK_STREAM; /* IP */
-    hints.ai_flags = AI_CANONNAME;   /* canonical name */
-    struct addrinfo* info;
-    while (true) {
-        int const retCode = getaddrinfo(hostname.data(), "http", &hints, &info);
-        if (retCode == 0) break;
-        if (retCode == EAI_AGAIN) continue;
-        throw runtime_error("Registry::" + string(__func__) +
-                            " getaddrinfo failed: " + gai_strerror(retCode));
-    }
-    string fqdn;
-    for (struct addrinfo* p = info; p != NULL; p = p->ai_next) {
-        if (!fqdn.empty()) fqdn += ",";
-        fqdn += p->ai_canonname;
-    }
-    freeaddrinfo(info);
-    return fqdn;
-}
-
 }  // namespace
 
 namespace lsst::qserv::replica {
@@ -142,7 +94,8 @@ vector<WorkerInfo> Registry::workers() const {
 }
 
 void Registry::add(string const& name) const {
-    string const hostName = ::get_current_host_fqdn();
+    bool const all = true;
+    string const hostName = util::get_current_host_fqdn(all);
     auto const config = _serviceProvider->config();
     json const request =
             json::object({{"instance_id", _serviceProvider->instanceId()},

src/util/CMakeLists.txt

@@ -5,6 +5,7 @@ target_sources(util PRIVATE
     Bug.cc
     CmdLineParser.cc
     Command.cc
+    common.cc
     ConfigStore.cc
     DynamicWorkQueue.cc
     Error.cc
@@ -31,6 +32,7 @@ target_sources(util PRIVATE
 )
 
 target_link_libraries(util PUBLIC
+    boost_system
     log
 )
 

src/util/common.cc

@@ -0,0 +1,76 @@
+// -*- LSST-C++ -*-
+/*
+ * LSST Data Management System
+ * Copyright 2015 LSST Corporation.
+ *
+ * This product includes software developed by the
+ * LSST Project (http://www.lsst.org/).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the LSST License Statement and
+ * the GNU General Public License along with this program.  If not,
+ * see <http://www.lsstcorp.org/LegalNotices/>.
+ */
+// Class header
+#include "util/common.h"
+
+// Standard headers
+#include <netdb.h>
+#include <stdexcept>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+
+// Third-party headers
+#include "boost/asio.hpp"
+
+using namespace std;
+
+namespace lsst::qserv::util {
+
+string get_current_host_fqdn(bool all) {
+    // Get the short name of the current host first.
+    boost::system::error_code ec;
+    string const hostname = boost::asio::ip::host_name(ec);
+    if (ec.value() != 0) {
+        throw runtime_error("Registry::" + string(__func__) +
+                            " boost::asio::ip::host_name failed: " + ec.category().name() + string(":") +
+                            to_string(ec.value()) + "[" + ec.message() + "]");
+    }
+
+    // Get the host's FQDN(s)
+    struct addrinfo hints;
+    memset(&hints, 0, sizeof hints);
+    hints.ai_family = AF_UNSPEC;     /* either IPV4 or IPV6 */
+    hints.ai_socktype = SOCK_STREAM; /* IP */
+    hints.ai_flags = AI_CANONNAME;   /* canonical name */
+    struct addrinfo* info;
+    while (true) {
+        int const retCode = getaddrinfo(hostname.data(), "http", &hints, &info);
+        if (retCode == 0) break;
+        if (retCode == EAI_AGAIN) continue;
+        throw runtime_error("Registry::" + string(__func__) +
+                            " getaddrinfo failed: " + gai_strerror(retCode));
+    }
+    string fqdn;
+    for (struct addrinfo* p = info; p != NULL; p = p->ai_next) {
+        if (!fqdn.empty()) {
+            if (!all) break;
+            fqdn += ",";
+        }
+        fqdn += p->ai_canonname;
+    }
+    freeaddrinfo(info);
+    return fqdn;
+}
+
+}  // namespace lsst::qserv::util

src/util/common.h

@@ -38,6 +38,23 @@
 
 namespace lsst::qserv::util {
 
+/**
+ * Get the FQDN(s) of the current host.
+ *
+ * If there will be more than one canonical name associated with the host
+ * and if a value of the input parameter is set as "all=true" then the result
+ * will contain all names separated by comma, such as in:
+ * @code
+ *   <fqdn-1>,<fqdn-2>,...
+ * @endcode
+ * @note In most setups there will be just one name.
+ * @param all The optional parameter that allows returning all names instead
+ *   of the first one that was found.
+ * @return The FQDN (or FQDNs)
+ * @throws std::runtime_error In case if the information couldn't be retreived.
+ */
+std::string get_current_host_fqdn(bool all = false);
+
 template <class Map>
 typename Map::mapped_type const& getFromMap(Map const& m, typename Map::key_type const& key,
                                             typename Map::mapped_type const& defValue) {