Merge branch 'devel' of https://github.com/arangodb/arangodb into devel

CHANGELOG

@@ -1,6 +1,9 @@
 devel
 -----
 
+* change undocumented behaviour in case of invalid revision ids in
+  If-Match and If-None-Match headers from 400 (BAD) to 412 (PRECONDITION
+  FAILED).
 
 v3.2.alpha1 (2017-02-05)
 ------------------------

Documentation/Books/Manual/GettingStarted/Installing/Compiling.mdpp

@@ -12,6 +12,7 @@ By default, cloning the github repository will checkout **devel**. This version
 contains the development version of the ArangoDB.  Use this branch if you want
 to make changes to the ArangoDB source.
 
+On windows you first [need to allow and enable symlinks for your user](https://github.com/git-for-windows/git/wiki/Symbolic-Links#allowing-non-administrators-to-create-symbolic-links). 
 We now use [git submodules](https://git-scm.com/docs/git-submodule) for V8 and Rocksdb.
 Since the V8 git repository also requires external addons to be present, we end 
 up with recursive submodules. Thus a clone command now has to look like:
@@ -21,5 +22,8 @@ up with recursive submodules. Thus a clone command now has to look like:
     git submodule update --recursive
     git submodule update --init --recursive
 
+
+
+
 Please checkout the [cookbook](https://docs.arangodb.com/cookbook) on how to
 compile ArangoDB.

UnitTests/HttpInterface/api-document-delete-spec.rb

@@ -190,20 +190,20 @@ describe ArangoDB do
         hdr = { "if-match" => "\"*abcd\"" }
         doc = ArangoDB.log_delete("#{prefix}-rev-invalid", cmd, :headers => hdr )
 
-        doc.code.should eq(400)
+        doc.code.should eq(412)
         doc.parsed_response['error'].should eq(true)
-        doc.parsed_response['errorNum'].should eq(400)
+        doc.parsed_response['errorNum'].should eq(1200)
-        doc.parsed_response['code'].should eq(400)
+        doc.parsed_response['code'].should eq(412)
         
         # delete document, invalid revision
         cmd = "/_api/document/#{did}"
         hdr = { "if-match" => "'*abcd'" }
         doc = ArangoDB.log_delete("#{prefix}-rev-invalid", cmd, :headers => hdr)
 
-        doc.code.should eq(400)
+        doc.code.should eq(412)
         doc.parsed_response['error'].should eq(true)
-        doc.parsed_response['errorNum'].should eq(400)
+        doc.parsed_response['errorNum'].should eq(1200)
-        doc.parsed_response['code'].should eq(400)
+        doc.parsed_response['code'].should eq(412)
         
         # delete document, correct revision
         cmd = "/_api/document/#{did}"

UnitTests/HttpInterface/api-document-read-spec.rb

@@ -567,7 +567,7 @@ describe ArangoDB do
         hdr = { "if-match" => "'*abcd'" }
         doc = ArangoDB.log_head("#{prefix}-head-rev-invalid", cmd, :headers => hdr)
         
-        doc.code.should eq(400)
+        doc.code.should eq(412)
       end
 
     end

UnitTests/HttpInterface/api-document-update-spec.rb

@@ -266,20 +266,20 @@ describe ArangoDB do
         hdr = { "if-match" => "\"*abcd\"" }
         doc = ArangoDB.log_put("#{prefix}-rev-invalid", cmd, :headers => hdr, :body => body)
 
-        doc.code.should eq(400)
+        doc.code.should eq(412)
         doc.parsed_response['error'].should eq(true)
-        doc.parsed_response['errorNum'].should eq(400)
+        doc.parsed_response['errorNum'].should eq(1200)
-        doc.parsed_response['code'].should eq(400)
+        doc.parsed_response['code'].should eq(412)
         
         # update document, invalid revision
         cmd = "/_api/document/#{did}"
         hdr = { "if-match" => "'*abcd'" }
         doc = ArangoDB.log_put("#{prefix}-rev-invalid", cmd, :headers => hdr, :body => body)
 
-        doc.code.should eq(400)
+        doc.code.should eq(412)
         doc.parsed_response['error'].should eq(true)
-        doc.parsed_response['errorNum'].should eq(400)
+        doc.parsed_response['errorNum'].should eq(1200)
-        doc.parsed_response['code'].should eq(400)
+        doc.parsed_response['code'].should eq(412)
         
         # update document, correct revision
         cmd = "/_api/document/#{did}"

arangod/Agency/AgencyComm.cpp

@@ -1529,7 +1529,15 @@ AgencyCommResult AgencyComm::send(
       << "': " << body;
 
   arangodb::httpclient::SimpleHttpClient client(connection, timeout, false);
-  client.setJwt(ClusterComm::instance()->jwt());
+  auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr only happens during controlled shutdown
+    result._message = "could not send request to agency because of shutdown";
+    LOG_TOPIC(TRACE, Logger::AGENCYCOMM) << "could not send request to agency";
+
+    return result;
+  }
+  client.setJwt(cc->jwt());
   client.keepConnectionOnDestruction(true);
 
   // set up headers

arangod/Agency/Agent.cpp

@@ -313,6 +313,11 @@ bool Agent::recvAppendEntriesRPC(
 
 /// Leader's append entries
 void Agent::sendAppendEntriesRPC() {
+  auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr only happens during controlled shutdown
+    return;
+  }
 
   // _lastSent, _lastHighest and _confirmed only accessed in main thread
   std::string const myid = id();
@@ -387,7 +392,7 @@ void Agent::sendAppendEntriesRPC() {
       // Send request
       auto headerFields =
         std::make_unique<std::unordered_map<std::string, std::string>>();
-      arangodb::ClusterComm::instance()->asyncRequest(
+      cc->asyncRequest(
         "1", 1, _config.poolAt(followerId),
         arangodb::rest::RequestType::POST, path.str(),
         std::make_shared<std::string>(builder.toJson()), headerFields,
@@ -1002,6 +1007,11 @@ TimePoint const& Agent::leaderSince() const {
 
 // Notify inactive pool members of configuration change()
 void Agent::notifyInactive() const {
+  auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr only happens during controlled shutdown
+    return;
+  }
 
   std::map<std::string, std::string> pool = _config.pool();
   std::string path = "/_api/agency_priv/inform";
@@ -1023,7 +1033,7 @@ void Agent::notifyInactive() const {
       auto headerFields =
         std::make_unique<std::unordered_map<std::string, std::string>>();
 
-      arangodb::ClusterComm::instance()->asyncRequest(
+      cc->asyncRequest(
         "1", 1, p.second, arangodb::rest::RequestType::POST,
         path, std::make_shared<std::string>(out.toJson()), headerFields,
         nullptr, 1.0, true);

arangod/Agency/AgentActivator.cpp

@@ -66,11 +66,15 @@ void AgentActivator::run() {
 
     auto headerFields =
       std::make_unique<std::unordered_map<std::string, std::string>>();
-    arangodb::ClusterComm::instance()->asyncRequest(
+    auto cc = arangodb::ClusterComm::instance();
+    if (cc != nullptr) {
+      // nullptr only happens on controlled shutdown
+      cc->asyncRequest(
         "1", 1, endpoint, rest::RequestType::POST, path,
         std::make_shared<std::string>(allLogs->toJson()), headerFields,
         std::make_shared<ActivationCallback>(_agent, _failed, _replacement),
         5.0, true, 1.0);
+    }
 
     _cv.wait(10000000); // 10 sec
 

arangod/Agency/Constituent.cpp

@@ -389,11 +389,17 @@ void Constituent::callElection() {
        << "&prevLogTerm=" << _agent->lastLog().term;
 
   // Ask everyone for their vote
+  auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // only happens on controlled shutdown
+    follow(_term);
+    return;
+  }
   for (auto const& i : active) {
     if (i != _id) {
       auto headerFields =
         std::make_unique<std::unordered_map<std::string, std::string>>();
-      ClusterComm::instance()->asyncRequest(
+      cc->asyncRequest(
         "", coordinatorTransactionID, _agent->config().poolAt(i),
         rest::RequestType::GET, path.str(),
         std::make_shared<std::string>(body), headerFields,
@@ -419,8 +425,7 @@ void Constituent::callElection() {
       break;
     }
     
-    auto res = ClusterComm::instance()->wait(
+    auto res = cc->wait("", coordinatorTransactionID, 0, "",
-      "", coordinatorTransactionID, 0, "",
       duration<double>(steady_clock::now()-timeout).count());
 
     if (res.status == CL_COMM_SENT) {
@@ -461,7 +466,7 @@ void Constituent::callElection() {
     << (yea >= majority ? "yeas" : "nays") << " have it.";
 
   // Clean up
-  ClusterComm::instance()->drop("", coordinatorTransactionID, 0, "");
+  cc->drop("", coordinatorTransactionID, 0, "");
   
 }
 

arangod/Agency/Inception.cpp

@@ -49,6 +49,11 @@ Inception::~Inception() { shutdown(); }
 /// - Create outgoing gossip.
 /// - Send to all peers
 void Inception::gossip() {
+  auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr only happens during controlled shutdown
+    return;
+  }
 
   LOG_TOPIC(INFO, Logger::AGENCY) << "Entering gossip phase ...";
   using namespace std::chrono;
@@ -93,7 +98,7 @@ void Inception::gossip() {
           std::make_unique<std::unordered_map<std::string, std::string>>();
         LOG_TOPIC(DEBUG, Logger::AGENCY) << "Sending gossip message: "
             << out->toJson() << " to peer " << clientid;
-        arangodb::ClusterComm::instance()->asyncRequest(
+        cc->asyncRequest(
           clientid, 1, p, rest::RequestType::POST, path,
           std::make_shared<std::string>(out->toJson()), hf,
           std::make_shared<GossipCallback>(_agent, version), 1.0, true, 0.5);
@@ -116,7 +121,7 @@ void Inception::gossip() {
           std::make_unique<std::unordered_map<std::string, std::string>>();
         LOG_TOPIC(DEBUG, Logger::AGENCY) << "Sending gossip message: "
             << out->toJson() << " to pool member " << clientid;
-        arangodb::ClusterComm::instance()->asyncRequest(
+        cc->asyncRequest(
           clientid, 1, pair.second, rest::RequestType::POST, path,
           std::make_shared<std::string>(out->toJson()), hf,
           std::make_shared<GossipCallback>(_agent, version), 1.0, true, 0.5);
@@ -156,6 +161,11 @@ void Inception::gossip() {
 
 
 bool Inception::restartingActiveAgent() {
+  auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr only happens during controlled shutdown
+    return false;
+  }
 
   LOG_TOPIC(INFO, Logger::AGENCY) << "Restarting agent from persistence ...";
 
@@ -200,7 +210,7 @@ bool Inception::restartingActiveAgent() {
     std::vector<std::string> informed;
     
     for (auto& p : gp) {
-      auto comres = arangodb::ClusterComm::instance()->syncRequest(
+      auto comres = cc->syncRequest(
         clientId, 1, p, rest::RequestType::POST, path, greetstr,
         std::unordered_map<std::string, std::string>(), 2.0);
       if (comres->status == CL_COMM_SENT) {
@@ -224,7 +234,7 @@ bool Inception::restartingActiveAgent() {
       
       if (p.first != myConfig.id() && p.first != "") {
         
-        auto comres = arangodb::ClusterComm::instance()->syncRequest(
+        auto comres = cc->syncRequest(
           clientId, 1, p.second, rest::RequestType::POST, path, greetstr,
           std::unordered_map<std::string, std::string>(), 2.0);
         
@@ -249,7 +259,7 @@ bool Inception::restartingActiveAgent() {
 
               // Contact leader to update endpoint
               if (theirLeaderId != theirId) { 
-                comres = arangodb::ClusterComm::instance()->syncRequest(
+                comres = cc->syncRequest(
                   clientId, 1, theirLeaderEp, rest::RequestType::POST, path,
                   greetstr, std::unordered_map<std::string, std::string>(), 2.0);
                 // Failed to contact leader move on until we do. This way at
@@ -365,6 +375,11 @@ void Inception::reportVersionForEp(std::string const& endpoint, size_t version)
 
 
 bool Inception::estimateRAFTInterval() {
+  auto cc = arangodb::ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr only happens during controlled shutdown
+    return false;
+  }
 
   using namespace std::chrono;
   LOG_TOPIC(INFO, Logger::AGENCY) << "Estimating RAFT timeouts ...";
@@ -382,7 +397,7 @@ bool Inception::estimateRAFTInterval() {
         std::string clientid = peer.first + std::to_string(i);
         auto hf =
           std::make_unique<std::unordered_map<std::string, std::string>>();
-        arangodb::ClusterComm::instance()->asyncRequest(
+        cc->asyncRequest(
           clientid, 1, peer.second, rest::RequestType::GET, path,
           std::make_shared<std::string>(), hf,
           std::make_shared<MeasureCallback>(this, peer.second, timeStamp()),
@@ -448,7 +463,7 @@ bool Inception::estimateRAFTInterval() {
     for (auto const& peer : config.pool()) {
       if (peer.first != myid) {
         auto clientId = "1";
-        auto comres   = arangodb::ClusterComm::instance()->syncRequest(
+        auto comres   = cc->syncRequest(
           clientId, 1, peer.second, rest::RequestType::POST, path,
           measjson, std::unordered_map<std::string, std::string>(), 5.0);
       }

arangod/Agency/Store.cpp

@@ -352,11 +352,15 @@ std::vector<bool> Store::apply(
         auto headerFields =
           std::make_unique<std::unordered_map<std::string, std::string>>();
         
-        arangodb::ClusterComm::instance()->asyncRequest(
+        auto cc = ClusterComm::instance();
+        if (cc != nullptr) {
+          // nullptr only happens on controlled shutdown
+          cc->asyncRequest(
             "1", 1, endpoint, rest::RequestType::POST, path,
             std::make_shared<std::string>(body.toString()), headerFields,
-          std::make_shared<StoreCallback>(path, body.toJson()), 1.0, true, 0.01);
+            std::make_shared<StoreCallback>(path, body.toJson()), 1.0, true,
-        
+            0.01);
+        }
       } else {
         LOG_TOPIC(WARN, Logger::AGENCY) << "Malformed URL " << url;
       }

arangod/Aql/ClusterBlocks.cpp

@@ -1233,6 +1233,8 @@ std::unique_ptr<ClusterCommResult> RemoteBlock::sendRequest(
     std::string const& body) const {
   DEBUG_BEGIN_BLOCK();
   auto cc = ClusterComm::instance();
+  if (cc != nullptr) {
+    // nullptr only happens on controlled shutdown
 
     // Later, we probably want to set these sensibly:
     ClientTransactionID const clientTransactionId = "AQL";
@@ -1257,6 +1259,8 @@ std::unique_ptr<ClusterCommResult> RemoteBlock::sendRequest(
 
       return result;
     }
+  }
+  return std::make_unique<ClusterCommResult>();
 
   // cppcheck-suppress style
   DEBUG_END_BLOCK();

arangod/Aql/ExecutionEngine.cpp

@@ -582,6 +582,8 @@ struct CoordinatorInstanciator : public WalkerWorker<ExecutionNode> {
     // << "\n";
 
     auto cc = arangodb::ClusterComm::instance();
+    if (cc != nullptr) {
+      // nullptr only happens on controlled shutdown
 
       std::string const url("/_db/"
                             + arangodb::basics::StringUtils::urlEncode(collection->vocbase->name()) +
@@ -593,6 +595,7 @@ struct CoordinatorInstanciator : public WalkerWorker<ExecutionNode> {
                        arangodb::rest::RequestType::POST,
                        url, body, headers, nullptr, 30.0);
     }
+  }
 
   /// @brief aggregateQueryIds, get answers for all shards in a Scatter/Gather
   void aggregateQueryIds(EngineInfo* info,
@@ -670,8 +673,8 @@ struct CoordinatorInstanciator : public WalkerWorker<ExecutionNode> {
     // now send the plan to the remote servers
     arangodb::CoordTransactionID coordTransactionID = TRI_NewTickServer();
     auto cc = arangodb::ClusterComm::instance();
-    TRI_ASSERT(cc != nullptr);
+    if (cc != nullptr) {
-
+      // nullptr only happens on controlled shutdown
       // iterate over all shards of the collection
       size_t nr = 0;
       auto shardIds = collection->shardIds();
@@ -693,6 +696,7 @@ struct CoordinatorInstanciator : public WalkerWorker<ExecutionNode> {
 
       aggregateQueryIds(info, cc, coordTransactionID, collection);
     }
+  }
 
   /// @brief buildEngineCoordinator, for a single piece
   ExecutionEngine* buildEngineCoordinator(EngineInfo* info) {
@@ -931,6 +935,10 @@ struct CoordinatorInstanciator : public WalkerWorker<ExecutionNode> {
                                         query->vocbase()->name()) +
                           "/_internal/traverser");
     auto cc = arangodb::ClusterComm::instance();
+    if (cc == nullptr) {
+      // nullptr only happens on controlled shutdown
+      return;
+    }
     bool hasVars = false;
     VPackBuilder varInfo;
     std::vector<aql::Variable const*> vars;
@@ -1229,6 +1237,11 @@ ExecutionEngine* ExecutionEngine::instantiateFromPlan(
           // Lock shard on DBserver:
           arangodb::CoordTransactionID coordTransactionID = TRI_NewTickServer();
           auto cc = arangodb::ClusterComm::instance();
+          if (cc == nullptr) {
+            // nullptr only happens on controlled shutdown
+            THROW_ARANGO_EXCEPTION( TRI_ERROR_SHUTTING_DOWN);
+          }
+
           TRI_vocbase_t* vocbase = query->vocbase();
           std::unique_ptr<ClusterCommResult> res;
           std::unordered_map<std::string, std::string> headers;
@@ -1263,6 +1276,8 @@ ExecutionEngine* ExecutionEngine::instantiateFromPlan(
         // the DBservers via HTTP:
         TRI_vocbase_t* vocbase = query->vocbase();
         auto cc = arangodb::ClusterComm::instance();
+        if (cc != nullptr) {
+          // nullptr only happens during controlled shutdown
           for (auto& q : inst.get()->queryIds) {
             std::string theId = q.first;
             std::string queryId = q.second;
@@ -1330,6 +1345,7 @@ ExecutionEngine* ExecutionEngine::instantiateFromPlan(
               }
             }
           }
+        }
         throw;
       }
     } else {

arangod/Aql/TraversalBlock.cpp

@@ -192,6 +192,8 @@ int TraversalBlock::shutdown(int errorCode) {
   // We have to clean up the engines in Coordinator Case.
   if (arangodb::ServerState::instance()->isCoordinator()) {
     auto cc = arangodb::ClusterComm::instance();
+    if (cc != nullptr) {
+      // nullptr only happens on controlled server shutdown
       std::string const url(
           "/_db/" + arangodb::basics::StringUtils::urlEncode(_trx->vocbase()->name()) +
           "/_internal/traverser/");
@@ -212,6 +214,7 @@ int TraversalBlock::shutdown(int errorCode) {
         }
       }
     }
+  }
 
   return ExecutionBlock::shutdown(errorCode);
 

arangod/Cluster/ClusterMethods.cpp

@@ -562,6 +562,10 @@ int revisionOnCoordinator(std::string const& dbname,
   // Set a few variables needed for our work:
   ClusterInfo* ci = ClusterInfo::instance();
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    return TRI_ERROR_SHUTTING_DOWN;
+  }
 
   // First determine the collection ID from the name:
   std::shared_ptr<LogicalCollection> collinfo;
@@ -636,6 +640,10 @@ int figuresOnCoordinator(std::string const& dbname, std::string const& collname,
   // Set a few variables needed for our work:
   ClusterInfo* ci = ClusterInfo::instance();
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    return TRI_ERROR_SHUTTING_DOWN;
+  }
 
   // First determine the collection ID from the name:
   std::shared_ptr<LogicalCollection> collinfo;
@@ -701,6 +709,10 @@ int countOnCoordinator(std::string const& dbname, std::string const& collname,
   // Set a few variables needed for our work:
   ClusterInfo* ci = ClusterInfo::instance();
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    return TRI_ERROR_SHUTTING_DOWN;
+  }
 
   result.clear();
 
@@ -771,6 +783,10 @@ int createDocumentOnCoordinator(
   // Set a few variables needed for our work:
   ClusterInfo* ci = ClusterInfo::instance();
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    return TRI_ERROR_SHUTTING_DOWN;
+  }
 
   // First determine the collection ID from the name:
   std::shared_ptr<LogicalCollection> collinfo;
@@ -906,6 +922,10 @@ int deleteDocumentOnCoordinator(
   // Set a few variables needed for our work:
   ClusterInfo* ci = ClusterInfo::instance();
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    return TRI_ERROR_SHUTTING_DOWN;
+  }
 
   // First determine the collection ID from the name:
   std::shared_ptr<LogicalCollection> collinfo;
@@ -1135,6 +1155,10 @@ int truncateCollectionOnCoordinator(std::string const& dbname,
   // Set a few variables needed for our work:
   ClusterInfo* ci = ClusterInfo::instance();
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    return TRI_ERROR_SHUTTING_DOWN;
+  }
 
   // First determine the collection ID from the name:
   std::shared_ptr<LogicalCollection> collinfo;
@@ -1191,6 +1215,10 @@ int getDocumentOnCoordinator(
   // Set a few variables needed for our work:
   ClusterInfo* ci = ClusterInfo::instance();
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    return TRI_ERROR_SHUTTING_DOWN;
+  }
 
   // First determine the collection ID from the name:
   std::shared_ptr<LogicalCollection> collinfo;
@@ -1462,6 +1490,10 @@ int fetchEdgesFromEngines(
     size_t& filtered,
     size_t& read) {
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    return TRI_ERROR_SHUTTING_DOWN;
+  }
   // TODO map id => ServerID if possible
   // And go fast-path
 
@@ -1546,6 +1578,10 @@ void fetchVerticesFromEngines(
         result,
     VPackBuilder& builder) {
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    return;
+  }
   // TODO map id => ServerID if possible
   // And go fast-path
 
@@ -1636,6 +1672,10 @@ int getFilteredEdgesOnCoordinator(
   // Set a few variables needed for our work:
   ClusterInfo* ci = ClusterInfo::instance();
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    return TRI_ERROR_SHUTTING_DOWN;
+  }
 
   // First determine the collection ID from the name:
   std::shared_ptr<LogicalCollection> collinfo =
@@ -1755,6 +1795,10 @@ int modifyDocumentOnCoordinator(
   // Set a few variables needed for our work:
   ClusterInfo* ci = ClusterInfo::instance();
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    return TRI_ERROR_SHUTTING_DOWN;
+  }
 
   // First determine the collection ID from the name:
   std::shared_ptr<LogicalCollection> collinfo =
@@ -2005,6 +2049,10 @@ int modifyDocumentOnCoordinator(
 int flushWalOnAllDBServers(bool waitForSync, bool waitForCollector) {
   ClusterInfo* ci = ClusterInfo::instance();
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    return TRI_ERROR_SHUTTING_DOWN;
+  }
   std::vector<ServerID> DBservers = ci->getCurrentDBServers();
   CoordTransactionID coordTransactionID = TRI_NewTickServer();
   std::string url = std::string("/_admin/wal/flush?waitForSync=") +

arangod/Cluster/HeartbeatThread.cpp

@@ -745,7 +745,8 @@ bool HeartbeatThread::handlePlanChangeCoordinator(uint64_t currentPlanVersion) {
   ClusterInfo::instance()->flush();
 
   // turn on error logging now
-  if (!ClusterComm::instance()->enableConnectionErrorLogging(true)) {
+  auto cc = ClusterComm::instance();
+  if (cc != nullptr && cc->enableConnectionErrorLogging(true)) {
     LOG_TOPIC(DEBUG, Logger::HEARTBEAT)
         << "created coordinator databases for the first time";
   }

arangod/Cluster/v8-cluster.cpp

@@ -1811,8 +1811,8 @@ static void JS_AsyncRequest(v8::FunctionCallbackInfo<v8::Value> const& args) {
   auto cc = ClusterComm::instance();
 
   if (cc == nullptr) {
-    TRI_V8_THROW_EXCEPTION_MESSAGE(TRI_ERROR_INTERNAL,
+    TRI_V8_THROW_EXCEPTION_MESSAGE(TRI_ERROR_SHUTTING_DOWN,
-                                   "clustercomm object not found");
+      "clustercomm object not found (JS_AsyncRequest)");
   }
 
   arangodb::rest::RequestType reqType;
@@ -1878,7 +1878,7 @@ static void JS_SyncRequest(v8::FunctionCallbackInfo<v8::Value> const& args) {
   auto cc = ClusterComm::instance();
 
   if (cc == nullptr) {
-    TRI_V8_THROW_EXCEPTION_MESSAGE(TRI_ERROR_INTERNAL,
+    TRI_V8_THROW_EXCEPTION_MESSAGE(TRI_ERROR_SHUTTING_DOWN,
                                    "clustercomm object not found");
   }
 
@@ -1931,7 +1931,7 @@ static void JS_Enquire(v8::FunctionCallbackInfo<v8::Value> const& args) {
 
   if (cc == nullptr) {
     TRI_V8_THROW_EXCEPTION_MESSAGE(TRI_ERROR_INTERNAL,
-                                   "clustercomm object not found");
+      "clustercomm object not found (JS_SyncRequest)");
   }
 
   OperationID operationID = TRI_ObjectToUInt64(args[0], true);
@@ -1967,8 +1967,8 @@ static void JS_Wait(v8::FunctionCallbackInfo<v8::Value> const& args) {
   auto cc = ClusterComm::instance();
 
   if (cc == nullptr) {
-    TRI_V8_THROW_EXCEPTION_MESSAGE(TRI_ERROR_INTERNAL,
+    TRI_V8_THROW_EXCEPTION_MESSAGE(TRI_ERROR_SHUTTING_DOWN,
-                                   "clustercomm object not found");
+                                   "clustercomm object not found (JS_Wait)");
   }
 
   ClientTransactionID myclientTransactionID = "";
@@ -2038,7 +2038,7 @@ static void JS_Drop(v8::FunctionCallbackInfo<v8::Value> const& args) {
 
   if (cc == nullptr) {
     TRI_V8_THROW_EXCEPTION_MESSAGE(TRI_ERROR_INTERNAL,
-                                   "clustercomm object not found");
+                                   "clustercomm object not found (JS_Drop)");
   }
 
   ClientTransactionID myclientTransactionID = "";
@@ -2116,9 +2116,13 @@ static void JS_ClusterDownload(v8::FunctionCallbackInfo<v8::Value> const& args)
     }
     options->Set(TRI_V8_ASCII_STRING("headers"), headers);
     
-    std::string const authorization = "bearer " + ClusterComm::instance()->jwt();
+    auto cc = ClusterComm::instance();
+    if (cc != nullptr) {
+      // nullptr happens only during controlled shutdown
+      std::string authorization = "bearer " + ClusterComm::instance()->jwt();
       v8::Handle<v8::String> v8Authorization = TRI_V8_STD_STRING(authorization);
       headers->Set(TRI_V8_ASCII_STRING("Authorization"), v8Authorization);
+    }
     args[2] = options;
   }
   TRI_V8_TRY_CATCH_END

arangod/RestHandler/RestDocumentHandler.cpp

@@ -203,23 +203,19 @@ bool RestDocumentHandler::readSingleDocument(bool generateBody) {
 
   // check for an etag
   bool isValidRevision;
-  TRI_voc_rid_t const ifNoneRid =
+  TRI_voc_rid_t ifNoneRid =
       extractRevision("if-none-match", isValidRevision);
   if (!isValidRevision) {
-    generateError(rest::ResponseCode::BAD,
+    ifNoneRid = 1;    // an impossible rev, so precondition failed will happen
-                  TRI_ERROR_HTTP_BAD_PARAMETER, "invalid revision number");
-    return false;
   }
 
   OperationOptions options;
   options.ignoreRevs = true;
 
-  TRI_voc_rid_t const ifRid =
+  TRI_voc_rid_t ifRid =
       extractRevision("if-match", isValidRevision);
   if (!isValidRevision) {
-    generateError(rest::ResponseCode::BAD,
+    ifRid = 1;    // an impossible rev, so precondition failed will happen
-                  TRI_ERROR_HTTP_BAD_PARAMETER, "invalid revision number");
-    return false;
   }
 
   VPackBuilder builder;
@@ -396,9 +392,7 @@ bool RestDocumentHandler::modifyDocument(bool isPatch) {
     bool isValidRevision;
     revision = extractRevision("if-match", isValidRevision);
     if (!isValidRevision) {
-      generateError(rest::ResponseCode::BAD,
+      revision = 1;   // an impossible revision, so precondition failed
-                    TRI_ERROR_HTTP_BAD_PARAMETER, "invalid revision number");
-      return false;
     }
     VPackSlice keyInBody = body.get(StaticStrings::KeyString);
     if ((revision != 0 && TRI_ExtractRevisionId(body) != revision) ||
@@ -502,9 +496,7 @@ bool RestDocumentHandler::deleteDocument() {
     bool isValidRevision = false;
     revision = extractRevision("if-match", isValidRevision);
     if (!isValidRevision) {
-      generateError(rest::ResponseCode::BAD,
+      revision = 1;   // an impossible revision, so precondition failed
-                    TRI_ERROR_HTTP_BAD_PARAMETER, "invalid revision number");
-      return false;
     }
   }
 

arangod/RestHandler/RestReplicationHandler.cpp

@@ -775,6 +775,12 @@ void RestReplicationHandler::handleTrampolineCoordinator() {
 
   // Set a few variables needed for our work:
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    // nullptr happens only during controlled shutdown
+    generateError(rest::ResponseCode::BAD, TRI_ERROR_SHUTTING_DOWN,
+                  "shutting down server");
+    return;
+  }
 
   std::unique_ptr<ClusterCommResult> res;
   if (!useVpp) {

arangod/Utils/Transaction.cpp

@@ -1917,6 +1917,8 @@ OperationResult Transaction::insertLocal(std::string const& collectionName,
                               path, body);
       }
       auto cc = arangodb::ClusterComm::instance();
+      if (cc != nullptr) {
+        // nullptr only happens on controlled shutdown
         size_t nrDone = 0;
         size_t nrGood = cc->performRequests(requests, chooseTimeout(count),
                                             nrDone, Logger::REPLICATION);
@@ -1946,6 +1948,7 @@ OperationResult Transaction::insertLocal(std::string const& collectionName,
         }
       }
     }
+  }
   
   if (options.silent) {
     // We needed the results, but do not want to report:
@@ -2175,7 +2178,8 @@ OperationResult Transaction::modifyLocal(
  
     // Now replicate the good operations on all followers:
     auto cc = arangodb::ClusterComm::instance();
-
+    if (cc != nullptr) {
+      // nullptr only happens on controlled shutdown
       std::string path
           = "/_db/" +
             arangodb::basics::StringUtils::urlEncode(_vocbase->name()) +
@@ -2256,6 +2260,7 @@ OperationResult Transaction::modifyLocal(
         }
       }
     }
+  }
   
   if (options.silent) {
     // We needed the results, but do not want to report:
@@ -2417,6 +2422,8 @@ OperationResult Transaction::removeLocal(std::string const& collectionName,
  
     // Now replicate the good operations on all followers:
     auto cc = arangodb::ClusterComm::instance();
+    if (cc != nullptr) {
+      // nullptr only happens on controled shutdown
 
       std::string path
           = "/_db/" +
@@ -2496,6 +2503,7 @@ OperationResult Transaction::removeLocal(std::string const& collectionName,
         }
       }
     }
+  }
   
   if (options.silent) {
     // We needed the results, but do not want to report:
@@ -2667,7 +2675,8 @@ OperationResult Transaction::truncateLocal(std::string const& collectionName,
 
       // Now replicate the good operations on all followers:
       auto cc = arangodb::ClusterComm::instance();
-
+      if (cc != nullptr) {
+        // nullptr only happens on controlled shutdown
         std::string path
             = "/_db/" +
               arangodb::basics::StringUtils::urlEncode(_vocbase->name()) +
@@ -2704,7 +2713,7 @@ OperationResult Transaction::truncateLocal(std::string const& collectionName,
             }
           }
         }
-
+      }
     }
   }
 

arangod/V8Server/v8-actions.cpp

@@ -1348,6 +1348,9 @@ static bool clusterSendToAllServers(
     arangodb::rest::RequestType const& method, std::string const& body) {
   ClusterInfo* ci = ClusterInfo::instance();
   auto cc = ClusterComm::instance();
+  if (cc == nullptr) {
+    return TRI_ERROR_SHUTTING_DOWN;
+  }
   std::string url = "/_db/" + StringUtils::urlEncode(dbname) + "/" + path;
 
   // Have to propagate to DB Servers

arangod/V8Server/v8-replication.cpp

@@ -209,10 +209,14 @@ void addReplicationAuthentication(v8::Isolate* isolate,
   if (!hasUsernamePassword) {
     auto cluster = application_features::ApplicationServer::getFeature<ClusterFeature>("Cluster");
     if (cluster->isEnabled()) {
+      auto cc = ClusterComm::instance();
+      if (cc != nullptr) {
+        // nullptr happens only during controlled shutdown
         config._jwt = ClusterComm::instance()->jwt();
       }
     }
   }
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief sync data from a remote master

arangod/V8Server/v8-vocbase.cpp

@@ -2138,7 +2138,8 @@ static void ListDatabasesCoordinator(
       if (!DBServers.empty()) {
         ServerID sid = DBServers[0];
         auto cc = ClusterComm::instance();
-
+        if (cc != nullptr) {
+          // nullptr happens only during controlled shutdown
           std::unordered_map<std::string, std::string> headers;
           headers["Authentication"] = TRI_ObjectToString(args[2]);
           auto res = cc->syncRequest(
@@ -2167,6 +2168,7 @@ static void ListDatabasesCoordinator(
             }
           }
         }
+      }
       if (++tries >= 2) {
         break;
       }