[QC-1260] Consider handling better invalid JSON from ccdbApi->list

The json error was already handled in the sense that it was not crashing and it was logging a human readable error.
I added a test and added a bit more output in case we don't find the objects we are looking for in the listing.

Author: Barthelemy

Framework/CMakeLists.txt

@@ -329,6 +329,7 @@ set(TEST_SRCS
     test/testTaskRunner.cxx
     test/testObjectsManager.cxx
     test/testCcdbDatabase.cxx
+    test/testCcdbDatabaseListingErrors.cxx
     test/testCcdbDatabaseExtra.cxx
     test/testTriggers.cxx
     test/testPostProcessingInterface.cxx
@@ -355,6 +356,7 @@ set(TEST_ARGS
     ""
     ""
     ""
+    ""
     "-b --run"
     "-b --run"
     ""

Framework/src/CcdbDatabase.cxx

@@ -524,7 +524,12 @@ core::ValidityInterval CcdbDatabase::getLatestObjectValidity(const std::string&
 
 std::vector<uint64_t> CcdbDatabase::getTimestampsForObject(const std::string& path)
 {
-  const auto& objects = getListingAsPtree(path).get_child("objects");
+  const auto listing = getListingAsPtree(path);
+  if (listing.count("objects") == 0) {
+    ILOG(Warning, Support) << "Could not get a valid listing from db '" << mUrl << "' for timestamps of '" << path << "'" << ENDM;
+    return {};
+  }
+  const auto& objects = listing.get_child("objects");
   std::vector<uint64_t> timestamps;
   timestamps.reserve(objects.size());
 
@@ -551,7 +556,13 @@ std::vector<std::string> CcdbDatabase::getPublishedObjectNames(std::string taskN
   try {
     boost::property_tree::read_json(ss, pt);
   } catch (const boost::property_tree::json_parser::json_parser_error&) {
-    ILOG(Error, Support) << "Failed to parse json in CcdbDatabase::getTimestampsForObject from data: " << ss.str() << ENDM;
+    ILOG(Error, Support) << "Failed to parse json in CcdbDatabase::getPublishedObjectNames from data: " << listing << ENDM;
+    return result;
+  }
+
+  if (pt.count("objects") == 0) {
+    ILOG(Warning, Support) << "Could not get a valid listing from db '" << mUrl << "' for published objects of '" << taskName << "'" << ENDM;
+    return result;
   }
 
   BOOST_FOREACH (boost::property_tree::ptree::value_type& v, pt.get_child("objects")) {

Framework/test/testCcdbDatabaseListingErrors.cxx

@@ -0,0 +1,142 @@
+// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
+// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+// All rights not expressly granted are reserved.
+//
+// This software is distributed under the terms of the GNU General Public
+// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+//
+// In applying this license CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+
+///
+/// \file   testCcdbDatabaseListingErrors.cxx
+/// \author Barthelemy von Haller
+///
+/// Reproduces issues with CCDB
+
+#include "QualityControl/CcdbDatabase.h"
+
+#define BOOST_TEST_MODULE CcdbDatabase listing errors test
+#define BOOST_TEST_MAIN
+#define BOOST_TEST_DYN_LINK
+
+#include <boost/test/unit_test.hpp>
+#include <boost/property_tree/ptree.hpp>
+
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include <atomic>
+#include <string>
+#include <thread>
+#include <vector>
+
+using namespace o2::quality_control::repository;
+
+namespace
+{
+
+constexpr const char* kServiceUnavailableHtml =
+  "<!doctype html><html lang=\"en\"><head><title>HTTP Status 503 – Service Unavailable</title></head>"
+  "<body><h1>HTTP Status 503 – Service Unavailable</h1>"
+  "<p><b>Message</b> Too many concurrent requests to /browse/ or /latest/ , cannot serve more</p>"
+  "<h3>Apache Tomcat/9.0.97</h3></body></html>";
+
+// Junie generated
+class Html503Server
+{
+ public:
+  Html503Server()
+  {
+    mListenFd = ::socket(AF_INET, SOCK_STREAM, 0);
+
+    int yes = 1;
+    ::setsockopt(mListenFd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes));
+
+    sockaddr_in addr{};
+    addr.sin_family = AF_INET;
+    addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+    addr.sin_port = htons(0);
+
+    socklen_t len = sizeof(addr);
+    mPort = ntohs(addr.sin_port);
+
+    mRunning = true;
+    mThread = std::thread([this] { run(); });
+  }
+
+  ~Html503Server()
+  {
+    mRunning = false;
+    if (mListenFd >= 0) {
+      ::shutdown(mListenFd, SHUT_RDWR);
+      ::close(mListenFd);
+      mListenFd = -1;
+    }
+    if (mThread.joinable()) {
+      mThread.join();
+    }
+  }
+
+  std::string url() const { return "http://127.0.0.1:" + std::to_string(mPort); }
+
+ private:
+  void run()
+  {
+    while (mRunning) {
+      sockaddr_in client{};
+      socklen_t clientLen = sizeof(client);
+      int clientFd = ::accept(mListenFd, reinterpret_cast<sockaddr*>(&client), &clientLen);
+      if (clientFd < 0) {
+        continue;
+      }
+      char buf[1024];
+      ::recv(clientFd, buf, sizeof(buf), 0);
+
+      const std::string body = kServiceUnavailableHtml;
+      std::string response =
+        "HTTP/1.1 503 Service Unavailable\r\n"
+        "Content-Type: text/html;charset=utf-8\r\n"
+        "Content-Length: " +
+        std::to_string(body.size()) +
+        "\r\n"
+        "Connection: close\r\n"
+        "\r\n" +
+        body;
+      ::send(clientFd, response.data(), response.size(), 0);
+      ::close(clientFd);
+    }
+  }
+
+  int mListenFd = -1;
+  int mPort = 0;
+  std::atomic<bool> mRunning{ false };
+  std::thread mThread;
+};
+
+} // namespace
+
+BOOST_AUTO_TEST_CASE(getPublishedObjectNames_handles_html_503)
+{
+  Html503Server server;
+  CcdbDatabase db;
+  db.connect(server.url(), "", "", "");
+
+  std::vector<std::string> names;
+  BOOST_CHECK_NO_THROW(names = db.getPublishedObjectNames("qc/TST/MO/SomeTask"));
+  BOOST_TEST(names.empty());
+}
+
+BOOST_AUTO_TEST_CASE(getListingAsPtree_handles_html_503)
+{
+  Html503Server server;
+  CcdbDatabase db;
+  db.connect(server.url(), "", "", "");
+
+  boost::property_tree::ptree listing;
+  BOOST_CHECK_NO_THROW(listing = db.getListingAsPtree("qc/TST/MO/SomeTask"));
+  BOOST_TEST(listing.count("objects") == 0);
+}