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arangodb/arangod/Cluster/ClusterComm.cpp

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////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2018 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
/// http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Max Neunhoeffer
////////////////////////////////////////////////////////////////////////////////
#include "ClusterComm.h"
#include "Agency/AgencyFeature.h"
#include "Agency/Agent.h"
#include "Basics/ConditionLocker.h"
#include "Basics/HybridLogicalClock.h"
#include "Basics/StringUtils.h"
#include "Cluster/ClusterInfo.h"
#include "Cluster/ServerState.h"
#include "GeneralServer/AuthenticationFeature.h"
#include "Logger/Logger.h"
#include "Scheduler/SchedulerFeature.h"
#include "SimpleHttpClient/SimpleHttpCommunicatorResult.h"
#include "Transaction/Methods.h"
#include "VocBase/ticks.h"
#include <thread>
#include <iomanip>
using namespace arangodb;
using namespace arangodb::communicator;
namespace {
std::stringstream createRequestInfo(NewRequest const& request) {
bool trace = Logger::CLUSTERCOMM.level() == LogLevel::TRACE;
std::stringstream ss;
ss << "id: " << std::setw(8) << std::setiosflags(std::ios::left)
<< request._ticketId << std::resetiosflags(std::ios::adjustfield)
<< " --> " << request._destination
<< " -- " << arangodb::GeneralRequest::translateMethod(request._request->requestType())
<< ": " << ( request._request->fullUrl().empty() ? "url unknown" : request._request->fullUrl())
;
if(trace){
try {
ss << " -- payload: '" << request._request->payload().toJson() << "'";
} catch (...) {
ss << " -- can not show payload";
}
}
return ss;
}
std::stringstream createResponseInfo(ClusterCommResult const* result) {
bool trace = Logger::CLUSTERCOMM.level() == LogLevel::TRACE;
std::stringstream ss;
ss << "id: " << std::setw(8) << std::setiosflags(std::ios::left)
<< result->operationID << std::resetiosflags(std::ios::adjustfield)
<< " <-- " << result->endpoint
<< " -- " << result->serverID << ":" << (result->shardID.empty() ? "unknown ShardID" : result->shardID)
;
if(trace){
try {
if(result->result){
ss << " -- payload: '" << result->result->getBody() << "'";
} else {
ss << " -- payload: no result";
}
} catch (...) {
ss << "can not show payload";
}
}
return ss;
}
}
/// @brief empty map with headers
std::unordered_map<std::string, std::string> const ClusterCommRequest::noHeaders;
/// @brief empty body
std::string const ClusterCommRequest::noBody;
/// @brief empty body, as a shared ptr
std::shared_ptr<std::string const> const ClusterCommRequest::sharedNoBody(new std::string());
//////////////////////////////////////////////////////////////////////////////
/// @brief the pointer to the singleton instance
//////////////////////////////////////////////////////////////////////////////
std::shared_ptr<ClusterComm> arangodb::ClusterComm::_theInstance;
//////////////////////////////////////////////////////////////////////////////
/// @brief the following atomic int is 0 in the beginning, is set to 1
/// if some thread initializes the singleton and is 2 once _theInstance
/// is set. Note that after a shutdown has happened, _theInstance can be
/// a nullptr, which means no new ClusterComm operations can be started.
//////////////////////////////////////////////////////////////////////////////
std::atomic<int> arangodb::ClusterComm::_theInstanceInit(0);
////////////////////////////////////////////////////////////////////////////////
/// @brief routine to set the destination
////////////////////////////////////////////////////////////////////////////////
void ClusterCommResult::setDestination(std::string const& dest, bool logConnectionErrors) {
// This sets result.shardId, result.serverId and result.endpoint,
// depending on what dest is. Note that if a shardID is given, the
// responsible server is looked up, if a serverID is given, the endpoint
// is looked up, both can fail and immediately lead to a CL_COMM_ERROR
// state.
if (dest.substr(0, 6) == "shard:") {
shardID = dest.substr(6);
{
std::shared_ptr<std::vector<ServerID>> resp =
ClusterInfo::instance()->getResponsibleServer(shardID);
if (!resp->empty()) {
serverID = (*resp)[0];
} else {
serverID = "";
status = CL_COMM_BACKEND_UNAVAILABLE;
if (logConnectionErrors) {
LOG_TOPIC("c3f33", ERR, Logger::CLUSTER)
<< "cannot find responsible server for shard '" << shardID << "'";
} else {
LOG_TOPIC("6d506", INFO, Logger::CLUSTER)
<< "cannot find responsible server for shard '" << shardID << "'";
}
return;
}
}
LOG_TOPIC("7b207", DEBUG, Logger::CLUSTER) << "Responsible server: " << serverID;
} else if (dest.substr(0, 7) == "server:") {
shardID = "";
serverID = dest.substr(7);
} else if (dest.substr(0, 6) == "tcp://" || dest.substr(0, 6) == "ssl://") {
shardID = "";
serverID = "";
endpoint = dest;
return; // all good
} else {
shardID = "";
serverID = "";
endpoint = "";
status = CL_COMM_BACKEND_UNAVAILABLE;
errorMessage = "did not understand destination'" + dest + "'";
if (logConnectionErrors) {
LOG_TOPIC("1671f", ERR, Logger::CLUSTER) << "did not understand destination '" << dest << "'";
} else {
LOG_TOPIC("ea4e3", INFO, Logger::CLUSTER) << "did not understand destination '" << dest << "'";
}
return;
}
// Now look up the actual endpoint:
auto ci = ClusterInfo::instance();
endpoint = ci->getServerEndpoint(serverID);
if (endpoint.empty()) {
status = CL_COMM_BACKEND_UNAVAILABLE;
if (serverID.find(',') != std::string::npos) {
TRI_ASSERT(false);
}
errorMessage = "did not find endpoint of server '" + serverID + "'";
if (logConnectionErrors) {
LOG_TOPIC("32152", ERR, Logger::CLUSTER)
<< "did not find endpoint of server '" << serverID << "'";
} else {
LOG_TOPIC("bd3e0", INFO, Logger::CLUSTER)
<< "did not find endpoint of server '" << serverID << "'";
}
}
}
/// @brief stringify the internal error state
std::string ClusterCommResult::stringifyErrorMessage() const {
// append status string
std::string result(stringifyStatus(status));
if (!serverID.empty()) {
result.append(", cluster node: '");
result.append(serverID);
result.push_back('\'');
}
if (!shardID.empty()) {
result.append(", shard: '");
result.append(shardID);
result.push_back('\'');
}
if (!endpoint.empty()) {
result.append(", endpoint: '");
result.append(endpoint);
result.push_back('\'');
}
if (!errorMessage.empty()) {
result.append(", error: '");
result.append(errorMessage);
result.push_back('\'');
}
return result;
}
/// @brief return an error code for a result
int ClusterCommResult::getErrorCode() const {
switch (status) {
case CL_COMM_SUBMITTED:
case CL_COMM_SENDING:
case CL_COMM_SENT:
case CL_COMM_RECEIVED:
return TRI_ERROR_NO_ERROR;
case CL_COMM_TIMEOUT:
return TRI_ERROR_CLUSTER_TIMEOUT;
case CL_COMM_ERROR:
case CL_COMM_DROPPED:
if (errorCode != TRI_ERROR_NO_ERROR) {
return errorCode;
}
return TRI_ERROR_INTERNAL;
case CL_COMM_BACKEND_UNAVAILABLE:
return TRI_ERROR_CLUSTER_BACKEND_UNAVAILABLE;
}
if (errorCode != TRI_ERROR_NO_ERROR) {
return errorCode;
}
return TRI_ERROR_INTERNAL;
}
/// @brief stringify a cluster comm status
char const* ClusterCommResult::stringifyStatus(ClusterCommOpStatus status) {
switch (status) {
case CL_COMM_SUBMITTED:
return "submitted";
case CL_COMM_SENDING:
return "sending";
case CL_COMM_SENT:
return "sent";
case CL_COMM_TIMEOUT:
return "timeout";
case CL_COMM_RECEIVED:
return "received";
case CL_COMM_ERROR:
return "error";
case CL_COMM_DROPPED:
return "dropped";
case CL_COMM_BACKEND_UNAVAILABLE:
return "backend unavailable";
}
return "unknown";
}
////////////////////////////////////////////////////////////////////////////////
/// @brief ClusterComm constructor
////////////////////////////////////////////////////////////////////////////////
ClusterComm::ClusterComm()
: _roundRobin(0),
_logConnectionErrors(false),
_authenticationEnabled(false),
_jwtAuthorization("") {
AuthenticationFeature* af = AuthenticationFeature::instance();
TRI_ASSERT(af != nullptr);
if (af->isActive()) {
std::string token = af->tokenCache().jwtToken();
TRI_ASSERT(!token.empty());
_authenticationEnabled = true;
_jwtAuthorization = "bearer " + token;
}
}
/// @brief Unit test constructor
ClusterComm::ClusterComm(bool ignored)
: _roundRobin(0),
_logConnectionErrors(false),
_authenticationEnabled(false),
_jwtAuthorization("") {} // ClusterComm::ClusterComm(bool)
////////////////////////////////////////////////////////////////////////////////
/// @brief ClusterComm destructor
////////////////////////////////////////////////////////////////////////////////
ClusterComm::~ClusterComm() { stopBackgroundThreads(); }
////////////////////////////////////////////////////////////////////////////////
/// @brief getter for our singleton instance
////////////////////////////////////////////////////////////////////////////////
std::shared_ptr<ClusterComm> ClusterComm::instance() {
int state = _theInstanceInit;
if (state < 2) {
// Try to set from 0 to 1:
while (state == 0) {
if (_theInstanceInit.compare_exchange_weak(state, 1)) {
break;
}
}
// Now state is either 0 (in which case we have changed _theInstanceInit
// to 1, or is 1, in which case somebody else has set it to 1 and is working
// to initialize the singleton, or is 2, in which case somebody else has
// done all the work and we are done:
if (state == 0) {
// we must initialize (cannot use std::make_shared here because
// constructor is private), if we throw here, everything is broken:
ClusterComm* cc = new ClusterComm();
_theInstance = std::shared_ptr<ClusterComm>(cc);
_theInstanceInit = 2;
} else if (state == 1) {
while (_theInstanceInit < 2) {
std::this_thread::yield();
}
}
}
// We want to achieve by other means that nobody requests a copy of the
// shared_ptr when the singleton is already destroyed. Therefore we put
// an assertion despite the fact that we have checks for nullptr in
// all places that call this method. Assertions have no effect in released
// code at the customer's site.
TRI_ASSERT(_theInstance != nullptr);
return _theInstance;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief initialize the cluster comm singleton object
////////////////////////////////////////////////////////////////////////////////
void ClusterComm::initialize() {
auto i = instance(); // this will create the static instance
i->startBackgroundThreads();
}
////////////////////////////////////////////////////////////////////////////////
/// @brief cleanup function to call once when shutting down
////////////////////////////////////////////////////////////////////////////////
void ClusterComm::cleanup() {
if (!_theInstance) {
return;
}
_theInstance.reset(); // no more operations will be started, but running
// ones have their copy of the shared_ptr
}
////////////////////////////////////////////////////////////////////////////////
/// @brief start the communication background threads
////////////////////////////////////////////////////////////////////////////////
void ClusterComm::startBackgroundThreads() {
for (unsigned loop = 0; loop < (TRI_numberProcessors() / 8 + 1); ++loop) {
ClusterCommThread* thread = new ClusterCommThread();
if (thread->start()) {
_backgroundThreads.push_back(thread);
} else {
LOG_TOPIC("a46a0", FATAL, Logger::CLUSTER)
<< "ClusterComm background thread does not work";
FATAL_ERROR_EXIT();
} // else
} // for
}
void ClusterComm::stopBackgroundThreads() {
// pass 1: tell all background threads to stop
for (ClusterCommThread* thread : _backgroundThreads) {
thread->beginShutdown();
} // for
// pass 2: verify each thread is stopped, wait if necessary
// (happens in destructor)
for (ClusterCommThread* thread : _backgroundThreads) {
delete thread;
}
_backgroundThreads.clear();
}
////////////////////////////////////////////////////////////////////////////////
/// @brief choose next communicator via round robin
////////////////////////////////////////////////////////////////////////////////
std::shared_ptr<communicator::Communicator> ClusterComm::communicator() {
unsigned index = (++_roundRobin) % _backgroundThreads.size();
return _backgroundThreads[index]->communicator();
}
////////////////////////////////////////////////////////////////////////////////
/// @brief produces an operation ID which is unique in this process
////////////////////////////////////////////////////////////////////////////////
OperationID ClusterComm::getOperationID() { return TRI_NewTickServer(); }
////////////////////////////////////////////////////////////////////////////////
/// @brief submit an HTTP request to a shard asynchronously.
///
/// This function queues a single HTTP request, usually to one of the
/// DBServers to be sent by ClusterComm in the background thread. If
/// `singleRequest` is false, as is the default, this request actually
/// orders an answer, which is an HTTP request sent from the target
/// DBServer back to us. Therefore ClusterComm also creates an entry in
/// a list of expected answers. One either has to use a callback for
/// the answer, or poll for it, or drop it to prevent memory leaks.
/// This call never returns a result directly, rather, it returns an
/// operation ID under which one can query the outcome with a wait() or
/// enquire() call (see below).
///
/// Use @ref enquire below to get information about the progress. The
/// actual answer is then delivered either in the callback or via
/// poll. If `singleRequest` is set to `true`, then the destination
/// can be an arbitrary server, the functionality can also be used in
/// single-Server mode, and the operation is complete when the single
/// request is sent and the corresponding answer has been received. We
/// use this functionality for the agency mode of ArangoDB.
/// The library takes ownerships of the pointer `headerFields` by moving
/// the unique_ptr to its own storage, this is necessary since this
/// method sometimes has to add its own headers. The library retains shared
/// ownership of `callback`. We use a shared_ptr for the body string
/// such that it is possible to use the same body in multiple requests.
///
/// Arguments:
/// `coordTransactionID` is a number describing the transaction the
/// coordinator is doing, `destination` is a string that either starts
/// with "shard:" followed by a shardID identifying the shard this
/// request is sent to, actually, this is internally translated into a
/// server ID. It is also possible to specify a DB server ID directly
/// here in the form of "server:" followed by a serverID. Furthermore,
/// it is possible to specify the target endpoint directly using
/// "tcp://..." or "ssl://..." endpoints, if `singleRequest` is true.
///
/// There are two timeout arguments. `timeout` is the globale timeout
/// specifying after how many seconds the complete operation must be
/// completed. `initTimeout` is a second timeout, which is used to
/// limit the time to send the initial request away. If `initTimeout`
/// is negative (as for example in the default value), then `initTimeout`
/// is taken to be the same as `timeout`. The idea behind the two timeouts
/// is to be able to specify correct behaviour for automatic failover.
/// The idea is that if the initial request cannot be sent within
/// `initTimeout`, one can retry after a potential failover.
////////////////////////////////////////////////////////////////////////////////
OperationID ClusterComm::asyncRequest(
CoordTransactionID const coordTransactionID, std::string const& destination,
arangodb::rest::RequestType reqtype, std::string const& path,
std::shared_ptr<std::string const> body,
std::unordered_map<std::string, std::string> const& headerFields,
std::shared_ptr<ClusterCommCallback> const& callback, ClusterCommTimeout timeout,
bool singleRequest, ClusterCommTimeout initTimeout) {
auto prepared = prepareRequest(destination, reqtype, body.get(), headerFields);
std::shared_ptr<ClusterCommResult> result(prepared.first);
result->coordTransactionID = coordTransactionID;
result->single = singleRequest;
std::unique_ptr<HttpRequest> request;
if (prepared.second == nullptr) {
request.reset(HttpRequest::createHttpRequest(ContentType::JSON, "", 0,
ClusterCommRequest::noHeaders));
request->setRequestType(reqtype); // mop: a fake but a good one
} else {
request.reset(prepared.second);
}
communicator::Options opt;
opt.connectionTimeout = initTimeout;
opt.requestTimeout = timeout;
Callbacks callbacks;
bool doLogConnectionErrors = logConnectionErrors();
callbacks._scheduleMe = scheduleMe;
if (callback) {
callbacks._onError = [callback, result, doLogConnectionErrors, this,
initTimeout](int errorCode, std::unique_ptr<GeneralResponse> response) {
{
CONDITION_LOCKER(locker, somethingReceived);
size_t numErased = responses.erase(result->operationID);
if (numErased == 0) {
// Request has been dropped, noone cares for it anymore.
// So do not call the callback (might be gone anyways)
return;
}
}
result->fromError(errorCode, std::move(response));
LOG_TOPIC("2345c", DEBUG, Logger::CLUSTERCOMM) << createResponseInfo(result.get()).rdbuf();
if (result->status == CL_COMM_BACKEND_UNAVAILABLE) {
logConnectionError(doLogConnectionErrors, result.get(), initTimeout, __LINE__);
}
/*bool ret =*/((*callback.get())(result.get()));
// TRI_ASSERT(ret == true);
};
callbacks._onSuccess = [callback, result, this](std::unique_ptr<GeneralResponse> response) {
{
CONDITION_LOCKER(locker, somethingReceived);
size_t numErased = responses.erase(result->operationID);
if (numErased == 0) {
// Request has been dropped, noone cares for it anymore.
// So do not call the callback (might be gone anyways)
return;
}
}
TRI_ASSERT(response.get() != nullptr);
result->fromResponse(std::move(response));
LOG_TOPIC("23457", DEBUG, Logger::CLUSTERCOMM) << createResponseInfo(result.get()).rdbuf();
/*bool ret =*/((*callback.get())(result.get()));
// TRI_ASSERT(ret == true);
};
} else {
callbacks._onError = [result, doLogConnectionErrors, this,
initTimeout](int errorCode, std::unique_ptr<GeneralResponse> response) {
// If the result has been removed from responses we are the last ones
// having a shared_ptr So it will be gone after this callback
CONDITION_LOCKER(locker, somethingReceived);
result->fromError(errorCode, std::move(response));
LOG_TOPIC("23458", DEBUG, Logger::CLUSTERCOMM) << createResponseInfo(result.get()).rdbuf();
if (result->status == CL_COMM_BACKEND_UNAVAILABLE) {
logConnectionError(doLogConnectionErrors, result.get(), initTimeout, __LINE__);
}
somethingReceived.broadcast();
};
callbacks._onSuccess = [result, this](std::unique_ptr<GeneralResponse> response) {
// If the result has been removed from responses we are the last ones
// having a shared_ptr So it will be gone after this callback
TRI_ASSERT(response.get() != nullptr);
CONDITION_LOCKER(locker, somethingReceived);
result->fromResponse(std::move(response));
LOG_TOPIC("23459", DEBUG, Logger::CLUSTERCOMM) << createResponseInfo(result.get()).rdbuf();
somethingReceived.broadcast();
};
}
TRI_ASSERT(request != nullptr);
// Call a random communicator
auto communicatorPtr = communicator();
auto newRequest = std::make_unique<communicator::NewRequest>(
createCommunicatorDestination(result->endpoint, path),
std::move(request),
std::move(callbacks),
opt);
LOG_TOPIC("2345a", DEBUG, Logger::CLUSTERCOMM) << createRequestInfo(*newRequest).rdbuf();
CONDITION_LOCKER(locker, somethingReceived);
auto ticketId = communicatorPtr->addRequest(std::move(newRequest));
result->operationID = ticketId;
responses.emplace(ticketId, AsyncResponse{TRI_microtime(), result,
std::move(communicatorPtr)});
return ticketId;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief submit a single HTTP request to a shard synchronously.
///
/// This function does an HTTP request synchronously, waiting for the
/// result. Note that the result has `status` field set to `CL_COMM_SENT`
/// and the field `result` is set to the HTTP response. The field `answer`
/// is unused in this case. In case of a timeout the field `status` is
/// `CL_COMM_TIMEOUT` and the field `result` points to an HTTP response
/// object that only says "timeout". Note that the ClusterComm library
/// does not keep a record of this operation, in particular, you cannot
/// use @ref enquire to ask about it.
///
/// Arguments: `coordTransactionID`
/// is a number describing the transaction the coordinator is doing,
/// shardID is a string that identifies the shard this request is sent to,
/// actually, this is internally translated into a server ID. It is also
/// possible to specify a DB server ID directly here.
////////////////////////////////////////////////////////////////////////////////
std::unique_ptr<ClusterCommResult> ClusterComm::syncRequest(
CoordTransactionID const coordTransactionID, std::string const& destination,
arangodb::rest::RequestType reqtype, std::string const& path, std::string const& body,
std::unordered_map<std::string, std::string> const& headerFields,
ClusterCommTimeout timeout) {
auto prepared = prepareRequest(destination, reqtype, &body, headerFields);
std::unique_ptr<ClusterCommResult> result(prepared.first);
// mop: this is used to distinguish a syncRequest from an asyncRequest while
// processing the answer...
result->single = true;
if (prepared.second == nullptr) {
return result;
}
std::unique_ptr<HttpRequest> request(prepared.second);
arangodb::basics::ConditionVariable cv;
bool doLogConnectionErrors = logConnectionErrors();
bool wasSignaled = false;
communicator::Callbacks callbacks(
[&cv, &result, &wasSignaled](std::unique_ptr<GeneralResponse> response) {
CONDITION_LOCKER(isen, cv);
result->fromResponse(std::move(response));
wasSignaled = true;
cv.signal();
},
[&cv, &result, &doLogConnectionErrors,
&wasSignaled](int errorCode, std::unique_ptr<GeneralResponse> response) {
CONDITION_LOCKER(isen, cv);
result->fromError(errorCode, std::move(response));
if (result->status == CL_COMM_BACKEND_UNAVAILABLE) {
logConnectionError(doLogConnectionErrors, result.get(), 0.0, __LINE__);
}
wasSignaled = true;
cv.signal();
});
callbacks._scheduleMe = scheduleMe;
communicator::Options opt;
opt.requestTimeout = timeout;
TRI_ASSERT(request != nullptr);
result->status = CL_COMM_SENDING;
auto newRequest = std::make_unique<communicator::NewRequest>(
createCommunicatorDestination(result->endpoint, path),
std::move(request),
callbacks,
opt);
LOG_TOPIC("34567", TRACE, Logger::CLUSTERCOMM) << createRequestInfo(*newRequest).rdbuf();
CONDITION_LOCKER(isen, cv);
// can't move callbacks here
communicator()->addRequest(std::move(newRequest));
while (!wasSignaled) {
cv.wait(100000);
}
LOG_TOPIC("2345b", DEBUG, Logger::CLUSTERCOMM) << createResponseInfo(result.get()).rdbuf();
return result;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief internal function to match an operation:
////////////////////////////////////////////////////////////////////////////////
bool ClusterComm::match(CoordTransactionID const coordTransactionID,
ShardID const& shardID, ClusterCommResult* res) {
return ((0 == coordTransactionID || coordTransactionID == res->coordTransactionID) &&
(shardID == "" || shardID == res->shardID));
}
////////////////////////////////////////////////////////////////////////////////
/// @brief check on the status of an operation
///
/// This call never blocks and returns information about a specific operation
/// given by `operationID`. Note that if the `status` is >= `CL_COMM_SENT`,
/// then the `result` field in the returned object is set, if the `status`
/// is `CL_COMM_RECEIVED`, then `answer` is set. However, in both cases
/// the ClusterComm library retains the operation in its queues! Therefore,
/// you have to use @ref wait or @ref drop to dequeue. Do not delete
/// `result` and `answer` before doing this! However, you have to delete
/// the ClusterCommResult pointer you get, it will automatically refrain
/// from deleting `result` and `answer`.
////////////////////////////////////////////////////////////////////////////////
ClusterCommResult const ClusterComm::enquire(communicator::Ticket const ticketId) {
ResponseIterator i;
AsyncResponse response;
{
CONDITION_LOCKER(locker, somethingReceived);
i = responses.find(ticketId);
if (i != responses.end()) {
response = i->second;
return *response.result.get();
}
}
ClusterCommResult res;
res.operationID = ticketId;
// does res.coordTransactionID need to be set here too?
res.status = CL_COMM_DROPPED;
return res;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief wait for one answer matching the criteria
///
/// If coordTransactionID is 0, then any
/// answer with any coordTransactionID matches. If shardID is empty,
/// then any answer from any ShardID matches. If operationID is 0, then
/// any answer with any operationID matches. This function returns
/// a result structure with status CL_COMM_DROPPED if no operation
/// matches. If `timeout` is given, the result can be a result structure
/// with status CL_COMM_TIMEOUT indicating that no matching answer was
/// available until the timeout was hit.
///
/// If timeout parameter is 0.0, code waits forever for a response (or error)
////////////////////////////////////////////////////////////////////////////////
ClusterCommResult const ClusterComm::wait(CoordTransactionID const coordTransactionID,
communicator::Ticket const ticketId,
ShardID const& shardID,
ClusterCommTimeout timeout) {
ResponseIterator i, i_erase;
AsyncResponse response;
bool match_good, status_ready;
ClusterCommTimeout endTime = TRI_microtime() + timeout;
TRI_ASSERT(timeout >= 0.0);
// if we cannot find the sought operation, we will return the status
// DROPPED. if we get into the timeout while waiting, we will still return
// CL_COMM_TIMEOUT.
ClusterCommResult return_result;
return_result.status = CL_COMM_DROPPED;
do {
CONDITION_LOCKER(locker, somethingReceived);
match_good = false;
status_ready = false;
if (ticketId == 0) {
i_erase = responses.end();
for (i = responses.begin(); i != responses.end() && !status_ready; i++) {
if (match(coordTransactionID, shardID, i->second.result.get())) {
match_good = true;
return_result = *i->second.result.get();
status_ready = (CL_COMM_SUBMITTED != return_result.status);
if (status_ready) {
i_erase = i;
} // if
} // if
} // for
// only delete from list after leaving loop
if (responses.end() != i_erase) {
responses.erase(i_erase);
} // if
} else {
TRI_ASSERT(ticketId != 0);
i = responses.find(ticketId);
if (i != responses.end()) {
return_result = *i->second.result.get();
TRI_ASSERT(return_result.operationID == ticketId);
status_ready = (CL_COMM_SUBMITTED != return_result.status);
match_good = true;
if (status_ready) {
responses.erase(i);
} // if
} else {
// Nothing known about this operation, return with failure:
return_result.operationID = ticketId;
// does res.coordTransactionID need to be set here too?
return_result.status = CL_COMM_DROPPED;
// tell Dispatcher that we are back in business
} // else
} // else
// at least one match, but no one ready
if (match_good && !status_ready) {
// give matching item(s) more time
ClusterCommTimeout now = TRI_microtime();
if (now < endTime || 0.0 == timeout) {
// convert to microseconds, use 10 second safety poll if no timeout
uint64_t micros = static_cast<uint64_t>(
0.0 != timeout ? ((endTime - now) * 1000000.0) : 10000000);
somethingReceived.wait(micros);
} else {
// time is up, leave
return_result.operationID = ticketId;
// does res.coordTransactionID need to be set here too?
return_result.status = CL_COMM_TIMEOUT;
match_good = false;
} // else
} // if
} while (!status_ready && match_good);
return return_result;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief ignore and drop current and future answers matching
///
/// If coordTransactionID is 0, then
/// any answer with any coordTransactionID matches. If shardID is
/// empty, then any answer from any ShardID matches. If operationID
/// is 0, then any answer with any operationID matches. If there
/// is already an answer for a matching operation, it is dropped and
/// freed. If not, any future answer coming in is automatically dropped.
/// This function can be used to automatically delete all information about an
/// operation, for which @ref enquire reported successful completion.
////////////////////////////////////////////////////////////////////////////////
void ClusterComm::drop(CoordTransactionID const coordTransactionID,
OperationID const operationID, ShardID const& shardID) {
// Loop through the responses queue
{
// Lock out the communicators to write responses in this very moment.
CONDITION_LOCKER(guard, somethingReceived);
ResponseIterator q = responses.begin();
while (q != responses.end()) {
ClusterCommResult* result = q->second.result.get();
// The result is not allowed to be deleted
TRI_ASSERT(result != nullptr);
if ((0 != operationID && result->operationID == operationID) ||
match(coordTransactionID, shardID, result)) {
// Abort on communicator does not trigger a function that requires responses list.
q->second.communicator->abortRequest(q->first);
q = responses.erase(q);
} else {
q++;
}
}
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief this method performs the given requests described by the vector
/// of ClusterCommRequest structs in the following way: all requests are
/// tried and the result is stored in the result component. Each request is
/// done with asyncRequest and the given timeout. If a request times out
/// it is considered to be a failure. If a connection cannot be created,
/// a retry is done with exponential backoff, that is, first after 1 second,
/// then after another 2 seconds, 4 seconds and so on, until the overall
/// timeout has been reached. A request that can connect and produces a
/// result is simply reported back with no retry, even in an error case.
/// The method returns the number of successful requests and puts the
/// number of finished ones in nrDone. Thus, the timeout was triggered
/// if and only if nrDone < requests.size().
////////////////////////////////////////////////////////////////////////////////
size_t ClusterComm::performRequests(std::vector<ClusterCommRequest>& requests,
ClusterCommTimeout timeout,
arangodb::LogTopic const& logTopic,
bool retryOnCollNotFound,
bool retryOnBackendUnavailable) {
if (requests.size() == 0) {
return 0;
}
CoordTransactionID coordinatorTransactionID = TRI_NewTickServer();
ClusterCommTimeout const startTime = TRI_microtime();
ClusterCommTimeout const endTime = startTime + timeout;
ClusterCommTimeout now = startTime;
std::vector<ClusterCommTimeout> dueTime;
dueTime.reserve(requests.size());
for (size_t i = 0; i < requests.size(); ++i) {
dueTime.push_back(startTime);
}
size_t nrGood = 0;
std::unordered_map<OperationID, size_t> opIDtoIndex;
try {
size_t nrDone = 0;
while (true) {
now = TRI_microtime();
if (now > endTime || application_features::ApplicationServer::isStopping()) {
break;
}
if (nrDone >= requests.size()) {
// All good, report
return nrGood;
}
double actionNeeded = endTime;
// First send away what is due:
for (size_t i = 0; i < requests.size(); i++) {
if (!requests[i].done) {
if (now >= dueTime[i]) {
LOG_TOPIC("60ecb", TRACE, logTopic)
<< "ClusterComm::performRequests: sending request to "
<< requests[i].destination << ":" << requests[i].path
<< "body:" << requests[i].getBody();
dueTime[i] = endTime + 10;
double localTimeout = endTime - now;
OperationID opId =
asyncRequest(coordinatorTransactionID, requests[i].destination,
requests[i].requestType, requests[i].path,
requests[i].getBodyShared(), requests[i].getHeaders(),
nullptr, localTimeout, false, 2.0);
TRI_ASSERT(opId != 0);
opIDtoIndex.insert(std::make_pair(opId, i));
// It is possible that an error occurs right away, we will notice
// below after wait(), though, and retry in due course.
} else if (dueTime[i] < actionNeeded) {
actionNeeded = dueTime[i];
}
}
}
TRI_ASSERT(actionNeeded >= now);
auto res = wait(coordinatorTransactionID, 0, "", actionNeeded - now);
// wait could have taken some time, so we need to update now now
now = TRI_microtime();
// note that this is needed further below from here, so it is *not*
// good enough to only update at the top of the loop!
if (res.status == CL_COMM_DROPPED) {
// this indicates that no request for this coordinatorTransactionID
// is in flight, this is possible, since we might have scheduled
// a retry later than now and simply wait till then
if (now < actionNeeded) {
std::this_thread::sleep_for(std::chrono::microseconds(
(unsigned long long)((actionNeeded - now) * 1000000.0)));
}
continue;
}
auto it = opIDtoIndex.find(res.operationID);
if (it == opIDtoIndex.end()) {
// Ooops, we got a response to which we did not send the request
LOG_TOPIC("41ac1", TRACE, Logger::CLUSTER)
<< "Received ClusterComm response for a request we did not send!";
continue;
}
size_t index = it->second;
if (retryOnCollNotFound) {
// If this flag is set we treat a 404 collection not found as
// a CL_COMM_BACKEND_UNAVAILABLE, which leads to a retry:
if (res.status == CL_COMM_RECEIVED && res.answer_code == rest::ResponseCode::NOT_FOUND) {
VPackSlice payload = res.answer->payload();
VPackSlice errorNum = payload.get(StaticStrings::ErrorNum);
if (errorNum.isInteger() && errorNum.getInt() == TRI_ERROR_ARANGO_DATA_SOURCE_NOT_FOUND) {
res.status = CL_COMM_BACKEND_UNAVAILABLE;
// This is a fake, but it will lead to a retry. If we timeout
// here and now, then the customer will get this result.
}
}
}
if (res.status == CL_COMM_RECEIVED) {
requests[index].result = res;
requests[index].done = true;
nrDone++;
if (res.answer_code == rest::ResponseCode::OK ||
res.answer_code == rest::ResponseCode::CREATED ||
res.answer_code == rest::ResponseCode::ACCEPTED ||
res.answer_code == rest::ResponseCode::NO_CONTENT) {
nrGood++;
}
LOG_TOPIC("fb401", TRACE, Logger::CLUSTER)
<< "ClusterComm::performRequests: "
<< "got answer from " << requests[index].destination << ":"
<< requests[index].path << " with return code " << (int)res.answer_code;
} else if ((res.status == CL_COMM_BACKEND_UNAVAILABLE && retryOnBackendUnavailable) ||
(res.status == CL_COMM_TIMEOUT && !res.sendWasComplete)) {
// Note that this case includes the refusal of a leader to accept
// the operation, in which we have to flush ClusterInfo:
ClusterInfo::instance()->loadCurrent();
requests[index].result = res;
now = TRI_microtime();
// In this case we will retry:
double tryAgainAfter = now - startTime;
if (tryAgainAfter < 0.2) {
tryAgainAfter = 0.2;
} else if (tryAgainAfter > 10.0) {
tryAgainAfter = 10.0;
}
dueTime[index] = tryAgainAfter + now;
if (dueTime[index] >= endTime) {
requests[index].done = true;
nrDone++;
}
LOG_TOPIC("54766", ERR, Logger::CLUSTER)
<< "ClusterComm::performRequests: "
<< "got BACKEND_UNAVAILABLE or TIMEOUT from "
<< requests[index].destination << ":" << requests[index].path;
} else { // a "proper error" which has to be returned to the client
requests[index].result = res;
requests[index].done = true;
nrDone++;
LOG_TOPIC("8f0bc", ERR, Logger::CLUSTER)
<< "ClusterComm::performRequests: "
<< "got no answer from " << requests[index].destination << ":"
<< requests[index].path << " with status "
<< res.stringifyStatus(res.status);
}
}
} catch (...) {
LOG_TOPIC("b2fb4", ERR, Logger::CLUSTER) << "ClusterComm::performRequests: "
<< "caught exception, ignoring...";
}
// We only get here if the global timeout was triggered, not all
// requests are marked by done!
LOG_TOPIC("a8502", DEBUG, logTopic) << "ClusterComm::performRequests: "
<< "got timeout, this will be reported...";
// Forget about
drop(coordinatorTransactionID, 0, "");
return nrGood;
}
std::string ClusterComm::createCommunicatorDestination(std::string const& endpoint,
std::string const& path) const {
std::string httpEndpoint;
// reserve enough space
httpEndpoint.reserve(endpoint.size() + 8);
if (endpoint.compare(0, 6, "tcp://") == 0) {
httpEndpoint.append("http://", 7);
httpEndpoint.append(endpoint.substr(6));
} else if (endpoint.compare(0, 6, "ssl://") == 0) {
httpEndpoint.append("https://", 8);
httpEndpoint.append(endpoint.substr(6));
}
httpEndpoint.append(path);
return httpEndpoint;
}
std::pair<ClusterCommResult*, HttpRequest*> ClusterComm::prepareRequest(
std::string const& destination, arangodb::rest::RequestType reqtype,
std::string const* body,
std::unordered_map<std::string, std::string> const& headerFields) {
HttpRequest* request = nullptr;
auto result = std::make_unique<ClusterCommResult>();
result->setDestination(destination, logConnectionErrors());
if (result->endpoint.empty()) {
return std::make_pair(result.release(), request);
}
result->status = CL_COMM_SUBMITTED;
std::unordered_map<std::string, std::string> headersCopy(headerFields);
addAuthorization(&headersCopy);
TRI_voc_tick_t timeStamp = TRI_HybridLogicalClock();
headersCopy[StaticStrings::HLCHeader] =
arangodb::basics::HybridLogicalClock::encodeTimeStamp(timeStamp);
auto state = ServerState::instance();
if (state->isCoordinator() || state->isDBServer()) {
headersCopy[StaticStrings::ClusterCommSource] = state->getId();
} else if (state->isAgent()) {
auto agent = AgencyFeature::AGENT;
if (agent != nullptr) {
headersCopy[StaticStrings::ClusterCommSource] = "AGENT-" + agent->id();
}
}
#ifdef DEBUG_CLUSTER_COMM
#ifdef ARANGODB_ENABLE_MAINTAINER_MODE
#if ARANGODB_ENABLE_BACKTRACE
std::string bt;
TRI_GetBacktrace(bt);
std::replace(bt.begin(), bt.end(), '\n', ';'); // replace all '\n' to ';'
headersCopy["X-Arango-BT-SYNC"] = bt;
#endif
#endif
#endif
if (body == nullptr) {
request = HttpRequest::createHttpRequest(ContentType::JSON, "", 0, headersCopy);
} else {
request = HttpRequest::createHttpRequest(ContentType::JSON, body->data(),
body->size(), headersCopy);
}
request->setRequestType(reqtype);
return std::make_pair(result.release(), request);
}
void ClusterComm::addAuthorization(std::unordered_map<std::string, std::string>* headers) {
if (_authenticationEnabled &&
headers->find(StaticStrings::Authorization) == headers->end()) {
headers->emplace(StaticStrings::Authorization, _jwtAuthorization);
}
}
std::vector<communicator::Ticket> ClusterComm::activeServerTickets(std::vector<std::string> const& servers) {
std::vector<communicator::Ticket> tickets;
CONDITION_LOCKER(locker, somethingReceived);
for (auto const& it : responses) {
for (auto const& server : servers) {
if (it.second.result && it.second.result->serverID == server) {
tickets.push_back(it.first);
}
}
}
return tickets;
}
void ClusterComm::disable() {
for (ClusterCommThread* thread : _backgroundThreads) {
thread->communicator()->disable();
thread->communicator()->abortRequests();
}
}
void ClusterComm::scheduleMe(std::function<void()> task) {
arangodb::SchedulerFeature::SCHEDULER->queue(RequestLane::CLUSTER_INTERNAL, std::move(task));
}
ClusterCommThread::ClusterCommThread() : Thread("ClusterComm"), _cc(nullptr) {
_cc = ClusterComm::instance().get();
_communicator = std::make_shared<communicator::Communicator>();
}
ClusterCommThread::~ClusterCommThread() { shutdown(); }
////////////////////////////////////////////////////////////////////////////////
/// @brief begin shutdown sequence
////////////////////////////////////////////////////////////////////////////////
void ClusterCommThread::beginShutdown() {
// Note that this is called from the destructor of the ClusterComm singleton
// object. This means that our pointer _cc is still valid and the condition
// variable in it is still OK. However, this method is called from a
// different thread than the ClusterCommThread. Therefore we can still
// use the condition variable to wake up the ClusterCommThread.
Thread::beginShutdown();
}
////////////////////////////////////////////////////////////////////////////////
/// @brief ClusterComm main loop
////////////////////////////////////////////////////////////////////////////////
void ClusterCommThread::abortRequestsToFailedServers() {
ClusterInfo* ci = ClusterInfo::instance();
auto failedServers = ci->getFailedServers();
if (failedServers.size() > 0) {
auto ticketIds = _cc->activeServerTickets(failedServers);
for (auto const& ticketId : ticketIds) {
_communicator->abortRequest(ticketId);
}
}
}
void ClusterCommThread::run() {
TRI_ASSERT(_communicator != nullptr);
LOG_TOPIC("74eda", DEBUG, Logger::CLUSTER) << "starting ClusterComm thread";
auto lastAbortCheck = std::chrono::steady_clock::now();
while (!application_features::ApplicationServer::isStopping()) {
try {
if (std::chrono::steady_clock::now() - lastAbortCheck >
std::chrono::duration<double>(3.0)) {
abortRequestsToFailedServers();
lastAbortCheck = std::chrono::steady_clock::now();
}
_communicator->work_once();
_communicator->wait();
LOG_TOPIC("9a40f", TRACE, Logger::CLUSTER) << "done waiting in ClusterCommThread";
} catch (std::exception const& ex) {
LOG_TOPIC("786aa", ERR, arangodb::Logger::CLUSTER)
<< "caught exception in ClusterCommThread: " << ex.what();
} catch (...) {
LOG_TOPIC("b55a2", ERR, arangodb::Logger::CLUSTER)
<< "caught unknown exception in ClusterCommThread";
}
}
_communicator->abortRequests();
LOG_TOPIC("2f95e", DEBUG, Logger::CLUSTER)
<< "waiting for curl to stop remaining handles";
while (_communicator->work_once() > 0) {
std::this_thread::sleep_for(std::chrono::microseconds(10));
}
LOG_TOPIC("5d12a", DEBUG, Logger::CLUSTER) << "stopped ClusterComm thread";
}
/// @brief logs a connection error (backend unavailable)
void ClusterComm::logConnectionError(bool useErrorLogLevel, ClusterCommResult const* result,
double timeout, int /*line*/) {
std::string msg = "cannot create connection to server";
if (!result->serverID.empty()) {
msg += ": '" + result->serverID + '\'';
}
msg += " at endpoint '" + result->endpoint + "', timeout: " + std::to_string(timeout);
if (useErrorLogLevel) {
LOG_TOPIC("30467", ERR, Logger::CLUSTER) << msg;
} else {
LOG_TOPIC("b82cb", INFO, Logger::CLUSTER) << msg;
}
}
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