fix #122: named pipe connection pooling

src/iisnode/cconnectionpool.cpp

@@ -0,0 +1,91 @@
+#include "precomp.h"
+
+CConnectionPool::CConnectionPool()
+	: count(0), list(NULL)
+{	
+}
+
+HRESULT CConnectionPool::Initialize(IHttpContext* ctx)
+{
+	HRESULT hr;
+
+	ErrorIf(NULL == (this->list = (PSLIST_HEADER)_aligned_malloc(sizeof(SLIST_HEADER), MEMORY_ALLOCATION_ALIGNMENT)), ERROR_NOT_ENOUGH_MEMORY);
+	this->maxPoolSize = 512; // TODO, expose configuration for this
+	this->maxAge = 30000; // TODO, expose configuration for this
+
+	InitializeSListHead(this->list);
+
+	return S_OK;
+Error:
+	return hr;
+}
+
+CConnectionPool::~CConnectionPool()
+{
+	PSLIST_ENTRY entry;
+
+	if (this->list)
+	{
+		while (NULL != (entry = InterlockedPopEntrySList(this->list)))
+		{
+			CloseHandle(((PCONNECTION_ENTRY)entry)->connection);
+			_aligned_free(entry);
+		}
+
+		_aligned_free(this->list);
+		this->list = NULL;
+	}
+}
+
+HRESULT CConnectionPool::Return(HANDLE connection)
+{
+	HRESULT hr;
+	PCONNECTION_ENTRY entry = NULL;
+
+	if (this->count >= this->maxPoolSize)
+	{
+		CloseHandle(connection);
+	}
+	else
+	{
+		ErrorIf(NULL == (entry = (PCONNECTION_ENTRY)_aligned_malloc(sizeof(CONNECTION_ENTRY), MEMORY_ALLOCATION_ALIGNMENT)), ERROR_NOT_ENOUGH_MEMORY);	
+		entry->connection = connection;
+		entry->timestamp = GetTickCount();
+		InterlockedPushEntrySList(this->list, &(entry->listEntry));	
+		InterlockedIncrement(&this->count);
+	}
+
+	return S_OK;
+Error:
+
+	return hr;
+}
+
+HANDLE CConnectionPool::Take()
+{
+	HANDLE result = INVALID_HANDLE_VALUE;
+	PCONNECTION_ENTRY entry;
+	DWORD now = GetTickCount();
+
+	while (NULL != (entry = (PCONNECTION_ENTRY)InterlockedPopEntrySList(this->list)))
+	{
+		InterlockedDecrement(&this->count);
+		if ((now - entry->timestamp) < this->maxAge)
+		{
+			result = entry->connection;
+		}
+		else
+		{
+			CloseHandle(entry->connection);
+		}
+
+		_aligned_free(entry);
+
+		if (INVALID_HANDLE_VALUE != result)
+		{
+			break;
+		}
+	}
+
+	return result;
+}

src/iisnode/cconnectionpool.h

@@ -0,0 +1,30 @@
+#ifndef __CCONNECTIONPOOL_H__
+#define __CCONNECTIONPOOL_H__
+
+class CConnectionPool
+{
+private:
+
+	typedef struct _CONNECTION_ENTRY {
+		SLIST_ENTRY listEntry;
+		HANDLE connection;
+		DWORD timestamp;
+	} CONNECTION_ENTRY, *PCONNECTION_ENTRY;
+
+	PSLIST_HEADER list;
+	unsigned long count;
+	DWORD maxPoolSize;
+	DWORD maxAge;
+
+public:
+
+	CConnectionPool();
+	~CConnectionPool();
+
+	HRESULT Initialize(IHttpContext* ctx);
+	HRESULT Return(HANDLE connection);
+	HANDLE Take();
+
+};
+
+#endif

src/iisnode/cnodehttpstoredcontext.cpp

@@ -4,7 +4,7 @@ CNodeHttpStoredContext::CNodeHttpStoredContext(CNodeApplication* nodeApplication
 	: nodeApplication(nodeApplication), context(context), process(NULL), buffer(NULL), bufferSize(0), dataSize(0), parsingOffset(0),
 	chunkLength(0), chunkTransmitted(0), isChunked(FALSE), pipe(INVALID_HANDLE_VALUE), result(S_OK), isLastChunk(FALSE),
 	requestNotificationStatus(RQ_NOTIFICATION_PENDING), connectionRetryCount(0), pendingAsyncOperationCount(1),
-	targetUrl(NULL), targetUrlLength(0), childContext(NULL)
+	targetUrl(NULL), targetUrlLength(0), childContext(NULL), isConnectionFromPool(FALSE)
 {
 	IHttpTraceContext* tctx;
 	LPCGUID pguid;
@@ -253,3 +253,13 @@ IHttpContext* CNodeHttpStoredContext::GetChildContext()
 {
 	return this->childContext;
 }
+
+BOOL CNodeHttpStoredContext::GetIsConnectionFromPool()
+{
+	return this->isConnectionFromPool;
+}
+
+void CNodeHttpStoredContext::SetIsConnectionFromPool(BOOL fromPool)
+{
+	this->isConnectionFromPool = fromPool;
+}

src/iisnode/cnodehttpstoredcontext.h

@@ -29,6 +29,7 @@ class CNodeHttpStoredContext : public IHttpStoredContext
 	DWORD targetUrlLength;
 	IHttpContext* childContext;
 	BOOL isLastChunk;
+	BOOL isConnectionFromPool;
 
 public:
 
@@ -79,6 +80,8 @@ class CNodeHttpStoredContext : public IHttpStoredContext
 	LPOVERLAPPED InitializeOverlapped();
 	long IncreasePendingAsyncOperationCount();
 	long DecreasePendingAsyncOperationCount();
+	BOOL GetIsConnectionFromPool();
+	void SetIsConnectionFromPool(BOOL fromPool);
 
 	static CNodeHttpStoredContext* Get(LPOVERLAPPED overlapped);
 

src/iisnode/cnodeprocess.cpp

@@ -70,6 +70,10 @@ HRESULT CNodeProcess::Initialize(IHttpContext* context)
 	RtlZeroMemory(&processInformation, sizeof processInformation);
 	RtlZeroMemory(&startupInfo, sizeof startupInfo);
 
+	// initialize connection pool
+
+	CheckError(this->connectionPool.Initialize(context));
+
 	// configure logging
 
 	if (TRUE == (this->loggingEnabled = CModuleConfiguration::GetLoggingEnabled(context)))
@@ -563,4 +567,9 @@ HRESULT CNodeProcess::CreateStdHandles(IHttpContext* context)
 	}
 
 	return hr;
-}
+}
+
+CConnectionPool* CNodeProcess::GetConnectionPool()
+{
+	return &this->connectionPool;
+}

src/iisnode/cnodeprocess.h

@@ -24,6 +24,7 @@ class CNodeProcess
 	BOOL hasProcessExited;
 	OVERLAPPED overlapped;
 	BOOL truncatePending;
+	CConnectionPool connectionPool;
 
 	static unsigned int WINAPI ProcessWatcher(void* arg);
 	void OnProcessExited();
@@ -39,6 +40,7 @@ class CNodeProcess
 	HRESULT Initialize(IHttpContext* context);
 	CNodeProcessManager* GetProcessManager();
 	LPCTSTR GetNamedPipeName();
+	CConnectionPool* GetConnectionPool();
 	HRESULT AcceptRequest(CNodeHttpStoredContext* context);
 	void OnRequestCompleted(CNodeHttpStoredContext* context);	
 	void SignalWhenDrained(HANDLE handle);

src/iisnode/cprotocolbridge.cpp

@@ -333,25 +333,42 @@ void WINAPI CProtocolBridge::CreateNamedPipeConnection(DWORD error, DWORD bytesT
 {
 	HRESULT hr;
 	CNodeHttpStoredContext* ctx = CNodeHttpStoredContext::Get(overlapped);
-	HANDLE pipe;
-
-	ErrorIf(INVALID_HANDLE_VALUE == (pipe = CreateFile(
-		ctx->GetNodeProcess()->GetNamedPipeName(),
-		GENERIC_READ | GENERIC_WRITE,
-		0,
-		NULL,
-		OPEN_EXISTING,
-		FILE_FLAG_OVERLAPPED,
-		NULL)), 
-		GetLastError());
-
-	ErrorIf(!SetFileCompletionNotificationModes(
-		pipe, 
-		FILE_SKIP_COMPLETION_PORT_ON_SUCCESS | FILE_SKIP_SET_EVENT_ON_HANDLE), 
-		GetLastError());
-
-	ctx->SetPipe(pipe);
-	ctx->GetNodeApplication()->GetApplicationManager()->GetAsyncManager()->AddAsyncCompletionHandle(pipe);
+	HANDLE pipe = INVALID_HANDLE_VALUE;
+	DWORD retry = ctx->GetConnectionRetryCount();
+
+	if (0 == retry)
+	{
+		// only the first connection attempt uses connections from the pool
+
+		pipe = ctx->GetNodeProcess()->GetConnectionPool()->Take();
+	}
+
+	if (INVALID_HANDLE_VALUE == pipe)
+	{
+		ErrorIf(INVALID_HANDLE_VALUE == (pipe = CreateFile(
+			ctx->GetNodeProcess()->GetNamedPipeName(),
+			GENERIC_READ | GENERIC_WRITE,
+			0,
+			NULL,
+			OPEN_EXISTING,
+			FILE_FLAG_OVERLAPPED,
+			NULL)), 
+			GetLastError());
+
+		ErrorIf(!SetFileCompletionNotificationModes(
+			pipe, 
+			FILE_SKIP_COMPLETION_PORT_ON_SUCCESS | FILE_SKIP_SET_EVENT_ON_HANDLE), 
+			GetLastError());
+
+		ctx->SetIsConnectionFromPool(FALSE);
+		ctx->GetNodeApplication()->GetApplicationManager()->GetAsyncManager()->AddAsyncCompletionHandle(pipe);
+	}
+	else
+	{
+		ctx->SetIsConnectionFromPool(TRUE);
+	}
+
+	ctx->SetPipe(pipe);	
 
 	ctx->GetNodeApplication()->GetApplicationManager()->GetEventProvider()->Log(
 		L"iisnode created named pipe connection to the node.exe process", WINEVENT_LEVEL_VERBOSE, ctx->GetActivityId());
@@ -364,7 +381,6 @@ void WINAPI CProtocolBridge::CreateNamedPipeConnection(DWORD error, DWORD bytesT
 
 	if (INVALID_HANDLE_VALUE == pipe) 
 	{
-		DWORD retry = ctx->GetConnectionRetryCount();
 		if (retry >= CModuleConfiguration::GetMaxNamedPipeConnectionRetry(ctx->GetHttpContext()))
 		{
 			if (hr == ERROR_PIPE_BUSY)
@@ -412,13 +428,11 @@ void CProtocolBridge::SendHttpRequestHeaders(CNodeHttpStoredContext* context)
 	GUID activityId;
 	memcpy(&activityId, context->GetActivityId(), sizeof GUID);
 
-	// request the named pipe to be closed by the server after the response is sent
-	// since we are not reusing named pipe connections anyway, requesting the server 
-	// to close it after sending the response allows the module to avoid parsing chunked responses
-	// to detect end of response
+	// request the named pipe to be kept alive by the server after the response is sent
+	// to enable named pipe connection pooling
 
 	request = context->GetHttpContext()->GetRequest();
-	CheckError(request->SetHeader(HttpHeaderConnection, "close", 5, TRUE));
+	CheckError(request->SetHeader(HttpHeaderConnection, "keep-alive", 10, TRUE));
 
 	// Expect: 100-continue has been processed by IIS - do not propagate it up to node.js since node will
 	// attempt to process it again
@@ -464,11 +478,22 @@ void CProtocolBridge::SendHttpRequestHeaders(CNodeHttpStoredContext* context)
 		{
 			// error
 
-			etw->Log(L"iisnode failed to initiate sending http request headers to the node.exe process", 
-				WINEVENT_LEVEL_ERROR, 
-				&activityId);
+			if (context->GetIsConnectionFromPool())
+			{
+				// communication over a connection from the connection pool failed
+				// try to create a brand new connection instead
 
-			CProtocolBridge::SendEmptyResponse(context, 500, _T("Internal Server Error"), hr);		
+				context->SetConnectionRetryCount(1);
+				CProtocolBridge::CreateNamedPipeConnection(S_OK, 0, context->GetOverlapped());
+			}
+			else
+			{
+				etw->Log(L"iisnode failed to initiate sending http request headers to the node.exe process", 
+					WINEVENT_LEVEL_ERROR, 
+					&activityId);
+
+				CProtocolBridge::SendEmptyResponse(context, 500, _T("Internal Server Error"), hr);		
+			}
 		}
 	}
 
@@ -498,9 +523,20 @@ void WINAPI CProtocolBridge::SendHttpRequestHeadersCompleted(DWORD error, DWORD
 	return;
 Error:
 
-	ctx->GetNodeApplication()->GetApplicationManager()->GetEventProvider()->Log(
-		L"iisnode failed to send http request headers to the node.exe process", WINEVENT_LEVEL_ERROR, ctx->GetActivityId());
-	CProtocolBridge::SendEmptyResponse(ctx, 500, _T("Internal Server Error"), hr);
+	if (ctx->GetIsConnectionFromPool())
+	{
+		// communication over a connection from the connection pool failed
+		// try to create a brand new connection instead
+
+		ctx->SetConnectionRetryCount(1);
+		CProtocolBridge::CreateNamedPipeConnection(S_OK, 0, ctx->GetOverlapped());
+	}
+	else
+	{
+		ctx->GetNodeApplication()->GetApplicationManager()->GetEventProvider()->Log(
+			L"iisnode failed to send http request headers to the node.exe process", WINEVENT_LEVEL_ERROR, ctx->GetActivityId());
+		CProtocolBridge::SendEmptyResponse(ctx, 500, _T("Internal Server Error"), hr);
+	}
 
 	return;
 }
@@ -1078,7 +1114,7 @@ void CProtocolBridge::FinalizeResponse(CNodeHttpStoredContext* context)
 	context->GetNodeApplication()->GetApplicationManager()->GetEventProvider()->Log(
 		L"iisnode finished processing http request/response", WINEVENT_LEVEL_VERBOSE, context->GetActivityId());
 
-	CloseHandle(context->GetPipe());
+	context->GetNodeProcess()->GetConnectionPool()->Return(context->GetPipe());
 	context->SetPipe(INVALID_HANDLE_VALUE);
 	CProtocolBridge::FinalizeResponseCore(
 		context, 

src/iisnode/iisnode.vcxproj

@@ -202,6 +202,7 @@ copy /y $(ProjectDir)\..\config\* $(ProjectDir)\..\..\build\$(Configuration)\$(P
   <ItemGroup>
     <ClCompile Include="cactiverequestpool.cpp" />
     <ClCompile Include="casyncmanager.cpp" />
+    <ClCompile Include="cconnectionpool.cpp" />
     <ClCompile Include="cfilewatcher.cpp" />
     <ClCompile Include="chttpprotocol.cpp" />
     <ClCompile Include="cmoduleconfiguration.cpp" />
@@ -325,6 +326,7 @@ copy /y $(ProjectDir)\..\config\* $(ProjectDir)\..\..\build\$(Configuration)\$(P
   <ItemGroup>
     <ClInclude Include="cactiverequestpool.h" />
     <ClInclude Include="casyncmanager.h" />
+    <ClInclude Include="cconnectionpool.h" />
     <ClInclude Include="cfilewatcher.h" />
     <ClInclude Include="chttpprotocol.h" />
     <ClInclude Include="cmoduleconfiguration.h" />

src/iisnode/iisnode.vcxproj.filters

@@ -164,6 +164,9 @@
     <ClCompile Include="cnodedebugger.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="cconnectionpool.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="precomp.h">
@@ -223,6 +226,9 @@
     <ClInclude Include="errors.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="cconnectionpool.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <None Include="iisnode.def">

src/iisnode/precomp.h

@@ -24,6 +24,7 @@
 //  Project header files
 #include "errors.h"
 #include "utils.h"
+#include "cconnectionpool.h"
 #include "cnodeeventprovider.h"
 #include "casyncmanager.h"
 #include "cmoduleconfiguration.h"