PluginHost Class Reference

Internal class, processes plugin validation requests from the main app. Request is a simple string formatted by detail::MakeRequestString. After connection is established host starts to wait for a request from server. Once request is successfully processed host sends a reply. Host is capable to handle only one request at a time, so it's not allowed to send another request until host hasn't finish processing previous request. More...

#include <PluginHost.h>

Inheritance diagram for PluginHost:

Collaboration diagram for PluginHost:

Public Member Functions
	PluginHost (int connectPort)
void	OnConnect (IPCChannel &channel) noexcept override
	Called when connection established. More...
void	OnDisconnect () noexcept override
	Invalidates IPCChannel passed as argument in OnConnect. More...
void	OnConnectionError () noexcept override
	Called when connection attempt fails. More...
void	OnDataAvailable (const void *data, size_t size) noexcept override
	Called when data chunk received as a result of a preceding call to IPCChannel::Send. Generally, data pointer should not be accessed outside this method, copied if necessary. More...
bool	Serve ()
Public Member Functions inherited from IPCChannelStatusCallback
virtual	~IPCChannelStatusCallback ()
virtual void	OnConnectionError () noexcept=0
	Called when connection attempt fails. More...
virtual void	OnConnect (IPCChannel &channel) noexcept=0
	Called when connection established. More...
virtual void	OnDisconnect () noexcept=0
	Invalidates IPCChannel passed as argument in OnConnect. More...
virtual void	OnDataAvailable (const void *data, size_t size) noexcept=0
	Called when data chunk received as a result of a preceding call to IPCChannel::Send. Generally, data pointer should not be accessed outside this method, copied if necessary. More...

Static Public Member Functions
static bool	Start (int connectPort)
	Attempts to start a host application (should be called from the main application) More...
static bool	IsHostProcess ()
	Returns true if current process is considered to be a plugin host process. More...

Private Member Functions
void	Stop () noexcept

Private Attributes
std::unique_ptr< IPCClient >	mClient
IPCChannel *	mChannel {nullptr}
detail::InputMessageReader	mInputMessageReader
std::mutex	mSync
std::condition_variable	mRequestCondition
std::optional< wxString >	mRequest
bool	mRunning {true}

Static Private Attributes
static constexpr auto	HostArgument = "--host"

Detailed Description

Internal class, processes plugin validation requests from the main app. Request is a simple string formatted by detail::MakeRequestString. After connection is established host starts to wait for a request from server. Once request is successfully processed host sends a reply. Host is capable to handle only one request at a time, so it's not allowed to send another request until host hasn't finish processing previous request.

Definition at line 35 of file PluginHost.h.

Constructor & Destructor Documentation

PluginHost()

PluginHost::PluginHost ( int  connectPort )

explicit

Definition at line 77 of file PluginHost.cpp.

{
   FileNames::InitializePathList();
   InitPreferences(audacity::ApplicationSettings::Call());
 
   auto& moduleManager = ModuleManager::Get();
   moduleManager.Initialize();
   moduleManager.DiscoverProviders();
 
   mClient = std::make_unique<IPCClient>(connectPort, *this);
}

References GlobalHook< ApplicationSettings, std::unique_ptr< BasicSettings >()>::Call(), ModuleManager::Get(), FileNames::InitializePathList(), InitPreferences(), and mClient.

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Member Function Documentation

IsHostProcess()

bool PluginHost::IsHostProcess ( )

static

Returns true if current process is considered to be a plugin host process.

Definition at line 202 of file PluginHost.cpp.

{
   return CommandLineArgs::argc >= 3 &&
      wxStrcmp(CommandLineArgs::argv[1], HostArgument) == 0;
}

References CommandLineArgs::argc, CommandLineArgs::argv, and HostArgument.

Referenced by LV2EffectsModule::Initialize(), AudacityApp::Initialize(), main(), ModuleDispatch(), and PluginHostModule::OnInit().

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OnConnect()

void PluginHost::OnConnect ( IPCChannel &  channel )

overridevirtualnoexcept

Called when connection established.

Parameters

channel

Using this channel client or server can send data to the other side.

Implements IPCChannelStatusCallback.

Definition at line 89 of file PluginHost.cpp.

{
   std::lock_guard lck(mSync);
   mChannel = &channel;
}

OnConnectionError()

void PluginHost::OnConnectionError ( )

overridevirtualnoexcept

Called when connection attempt fails.

Implements IPCChannelStatusCallback.

Definition at line 100 of file PluginHost.cpp.

{
   Stop();
}

References Stop().

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OnDataAvailable()

void PluginHost::OnDataAvailable ( const void *  data, size_t  size  )

overridevirtualnoexcept

Called when data chunk received as a result of a preceding call to IPCChannel::Send. Generally, data pointer should not be accessed outside this method, copied if necessary.

Parameters

data	Pointer to the chunk
size	Size of the chunk

Implements IPCChannelStatusCallback.

Definition at line 105 of file PluginHost.cpp.

{
   try
   {
      mInputMessageReader.ConsumeBytes(data, size);
      if(mInputMessageReader.CanPop())
      {
         {
            std::lock_guard lck(mSync);
            assert(!mRequest);
            mRequest = mInputMessageReader.Pop();
         }
         mRequestCondition.notify_one();
      }
   }
   catch(...)
   {
      Stop();
   }
}

References size.

OnDisconnect()

void PluginHost::OnDisconnect ( )

overridevirtualnoexcept

Invalidates IPCChannel passed as argument in OnConnect.

Implements IPCChannelStatusCallback.

Definition at line 95 of file PluginHost.cpp.

{
   Stop();
}

References Stop().

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Serve()

bool PluginHost::Serve

(

)

Definition at line 126 of file PluginHost.cpp.

{
   std::unique_lock lck(mSync);
   mRequestCondition.wait(lck, [this]{ return !mRunning || mRequest.has_value(); });
 
   if(!mRunning)
      return false;
 
   if(mRequest)
   {
      if(mChannel)
         detail::PutMessage(*mChannel, wxEmptyString);
 
      std::optional<wxString> request;
      mRequest.swap(request);
 
      lck.unlock();
      
      wxString providerId;
      wxString pluginPath;
      detail::PluginValidationResult result;
      if(detail::ParseRequestString(*request, providerId, pluginPath))
         Discover(result, providerId, pluginPath);
      else
         result.SetError("malformed request string");
 
      XMLStringWriter xmlWriter;
      result.WriteXML(xmlWriter);
 
      lck.lock();
      if(mChannel)
         detail::PutMessage(*mChannel, xmlWriter);
   }
 
   return true;
}

References anonymous_namespace{PluginHost.cpp}::Discover(), mChannel, mRequest, mRequestCondition, mRunning, mSync, detail::ParseRequestString(), detail::PutMessage(), detail::PluginValidationResult::SetError(), and detail::PluginValidationResult::WriteXML().

Referenced by PluginHostModule::OnInit().

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Start()

bool PluginHost::Start ( int  connectPort )

static

Attempts to start a host application (should be called from the main application)

Returns

true if host has started successfully

Definition at line 184 of file PluginHost.cpp.

{
   const auto cmd = wxString::Format("\"%s\" %s %d",
      PlatformCompatibility::GetExecutablePath(),
      PluginHost::HostArgument,
      connectPort);
 
   auto process = std::make_unique<wxProcess>();
   process->Detach();
   if(wxExecute(cmd, wxEXEC_ASYNC, process.get()) != 0)
   {
      //process will delete itself upon termination
      process.release();
      return true;
   }
   return false;
}

References PlatformCompatibility::GetExecutablePath(), and HostArgument.

Referenced by AsyncPluginValidator::Impl::StartHost().

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Stop()

void PluginHost::Stop ( )

privatenoexcept

Definition at line 164 of file PluginHost.cpp.

{
   try
   {
      {
         std::lock_guard lck(mSync);//may throw
         mRunning = false;
         mChannel = nullptr;
      }
   }
   catch(...)
   {
      //If something went wrong with mutex locking we'll try to
      //awake main thread if it's blocked on condition variable.
      //Attempt to relock the mutex there should throw as well(?)...
      //which, in turn, will result in std::terminate being called
   }
   mRequestCondition.notify_one();
}

References mChannel, mRequestCondition, mRunning, and mSync.

Referenced by OnConnectionError(), and OnDisconnect().

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Member Data Documentation

HostArgument

constexpr auto PluginHost::HostArgument = "--host"

staticconstexprprivate

Definition at line 37 of file PluginHost.h.

Referenced by IsHostProcess(), and Start().

mChannel

IPCChannel* PluginHost::mChannel {nullptr}

private

Definition at line 40 of file PluginHost.h.

Referenced by Serve(), and Stop().

mClient

std::unique_ptr<IPCClient> PluginHost::mClient

private

Definition at line 39 of file PluginHost.h.

Referenced by PluginHost().

mInputMessageReader

detail::InputMessageReader PluginHost::mInputMessageReader

private

Definition at line 41 of file PluginHost.h.

mRequest

std::optional<wxString> PluginHost::mRequest

private

Definition at line 44 of file PluginHost.h.

Referenced by Serve().

mRequestCondition

std::condition_variable PluginHost::mRequestCondition

private

Definition at line 43 of file PluginHost.h.

Referenced by Serve(), and Stop().

mRunning

bool PluginHost::mRunning {true}

private

Definition at line 46 of file PluginHost.h.

Referenced by Serve(), and Stop().

mSync

std::mutex PluginHost::mSync

private

Definition at line 42 of file PluginHost.h.

Referenced by Serve(), and Stop().

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The documentation for this class was generated from the following files:

• PluginHost.h
• PluginHost.cpp