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Solve race condition in JSON API restart

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Improve atomic access to restbed service
Protect JSON API restart against bursts
Fix JSON API error condition enum registration
Provide ostream helper for error_condition
Provide optional forced thread cancel for debugging purpose, disabled by
  default at compile time define RS_THREAD_FORCE_STOP to enable it
Avoid double fullstop in retroshare-gui json api apply button
This commit is contained in:
Gioacchino Mazzurco 2020-02-05 15:01:45 +01:00
parent 7757c685c5
commit 039e8f653d
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GPG key ID: A1FBCA3872E87051
8 changed files with 236 additions and 72 deletions
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36
libretroshare/src/jsonapi/jsonapi.h
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@ -30,6 +30,7 @@
#include <set>
#include <functional>
#include <vector>
#include <atomic>
#include "util/rsthreads.h"
#include "pqi/p3cfgmgr.h"
@ -40,6 +41,7 @@
namespace rb = restbed;
/** Interface to provide addotional resources to JsonApiServer */
class JsonApiResourceProvider
{
public:
@ -66,7 +68,7 @@ public:
void fullstop() override { RsThread::fullstop(); }
/// @see RsJsonApi
void restart() override;
std::error_condition restart() override;
/// @see RsJsonApi
void askForStop() override { RsThread::askForStop(); }
@ -145,10 +147,6 @@ public:
const std::function<bool(const std::string&, const std::string&)>&
callback );
/// @see RsJsonApi
const std::error_category& errorCategory() override
{ return sErrorCategory; }
protected:
/// @see RsThread
void onStopRequested() override;
@ -206,13 +204,33 @@ private:
std::reference_wrapper<const JsonApiResourceProvider>,
std::less<const JsonApiResourceProvider> > mResourceProviders;
/**
* This pointer should be accessed via std::atomic_* operations, up until
* now only very critical operations like reallocation, are done that way,
* but this is not still 100% thread safe, but seems to handle all of the
* test cases (no crash, no deadlock), once we switch to C++20 we shoud
* change this into std::atomic<std::shared_ptr<restbed::Service>> which
* will automatically handle atomic access properly all the times
*/
std::shared_ptr<restbed::Service> mService;
/** Protect service only during very critical operation like resetting the
* pointer, still not 100% thread safe, but hopefully we can avoid
* crashes/freeze with this */
RsMutex mServiceMutex;
uint16_t mListeningPort;
std::string mBindingAddress;
/// @see unProtectedRestart()
std::atomic<rstime_t> mRestartReqTS;
/// @see unProtectedRestart()
constexpr static rstime_t RESTART_BURST_PROTECTION = 7;
/** It is very important to protect this method from being called in bursts,
* because Restbed::Service::stop() together with
* Restbed::Service::start(...), which are called internally, silently fails
* if combined in bursts, probably because they have to deal with
* listening/releasing TCP port.
* @see JsonApiServer::restart() and @see JsonApiServer::JsonApiServer()
* implementation to understand how correctly use this.
*/
void unProtectedRestart();
};