Fix the poll socketengine to actually work.

The old implementation tried to use holes for unused entries in the array for
poll() and the OS replied with POLLNVAL to which we replied with 100% CPU.
Improvements:
- It does compile!
- It works


git-svn-id: http://svn.inspircd.org/repository/trunk/inspircd@11008 e03df62e-2008-0410-955e-edbf42e46eb7

2 files changed, 83 insertions, 30 deletions

diff --git a/include/socketengines/socketengine_poll.h b/include/socketengines/socketengine_poll.h
index f40cecd2c..1a85cff5e 100644
--- a/include/socketengines/socketengine_poll.h
+++ b/include/socketengines/socketengine_poll.h
@@ -43,6 +43,9 @@ private:
 	/** These are used by poll() to hold socket events
 	 */
 	struct pollfd *events;
+	/** This map maps fds to an index in the events array.
+	 */
+	std::map<int, unsigned int> fd_mappings;
 public:
 	/** Create a new PollEngine
 	 * @param Instance The creator of this object
@@ -52,6 +55,7 @@ public:
 	 */
 	virtual ~PollEngine();
 	virtual bool AddFd(EventHandler* eh);
+	virtual EventHandler* GetRef(int fd);
 	virtual int GetMaxFds();
 	virtual int GetRemainingFds();
 	virtual bool DelFd(EventHandler* eh, bool force = false);
diff --git a/src/socketengines/socketengine_poll.cpp b/src/socketengines/socketengine_poll.cpp
index c05ed25fa..242a4d96f 100644
--- a/src/socketengines/socketengine_poll.cpp
+++ b/src/socketengines/socketengine_poll.cpp
@@ -54,31 +54,49 @@ bool PollEngine::AddFd(EventHandler* eh)
 		return false;
 	}
 
-	if (ref[fd])
+	if (fd_mappings.find(fd) != fd_mappings.end())
 	{
 		ServerInstance->Logs->Log("SOCKET",DEBUG,"Attempt to add duplicate fd: %d", fd);
 		return false;
 	}
 
-	ref[fd] = eh;
-	events[fd].fd = fd;
+	unsigned int index = CurrentSetSize;
+
+	fd_mappings[fd] = index;
+	ref[index] = eh;
+	events[index].fd = fd;
 	if (eh->Readable())
 	{
-		events[fd].events = POLLIN;
+		events[index].events = POLLIN;
 	}
 	else
 	{
-		events[fd].events = POLLOUT;
+		events[index].events = POLLOUT;
 	}
 
-	ServerInstance->Logs->Log("SOCKET", DEBUG,"New file descriptor: %d (%d)", fd, events[fd].events);
+	ServerInstance->Logs->Log("SOCKET", DEBUG,"New file descriptor: %d (%d; index %d)", fd, events[fd].events, index);
 	CurrentSetSize++;
 	return true;
 }
 
+EventHandler* PollEngine::GetRef(int fd)
+{
+	std::map<int, unsigned int>::iterator it = fd_mappings.find(fd);
+	if (it == fd_mappings.end())
+		return NULL;
+	return ref[it->second];
+}
+
 void PollEngine::WantWrite(EventHandler* eh)
 {
-	events[eh->GetFd()].events = POLLIN | POLLOUT;
+	std::map<int, unsigned int>::iterator it = fd_mappings.find(eh->GetFd());
+	if (it == fd_mappings.end())
+	{
+		ServerInstance->Logs->Log("SOCKET",DEBUG,"WantWrite() on unknown fd: %d", eh->GetFd());
+		return;
+	}
+
+	events[it->second].events = POLLIN | POLLOUT;
 }
 
 bool PollEngine::DelFd(EventHandler* eh, bool force)
@@ -90,13 +108,42 @@ bool PollEngine::DelFd(EventHandler* eh, bool force)
 		return false;
 	}
 
-	events[fd].fd = -1;
-	events[fd].events = 0;
+	std::map<int, unsigned int>::iterator it = fd_mappings.find(fd);
+	if (it == fd_mappings.end())
+	{
+		ServerInstance->Logs->Log("SOCKET",DEBUG,"DelFd() on unknown fd: %d", fd);
+		return false;
+	}
+
+	unsigned int index = it->second;
+	unsigned int last_index = CurrentSetSize - 1;
+	int last_fd = events[last_index].fd;
+
+	if (index != last_index)
+	{
+		// We need to move the last fd we got into this gap (gaps are evil!)
+
+		// So update the mapping for the last fd to its new position
+		fd_mappings[last_fd] = index;
+
+		// move last_fd from last_index into index
+		events[index].fd = last_fd;
+		events[index].events = events[last_index].events;
+
+		ref[index] = ref[last_index];
+	}
+
+	// Now remove all data for the last fd we got into out list.
+	// Above code made sure this always is right
+	fd_mappings.erase(it);
+	events[last_index].fd = 0;
+	events[last_index].events = 0;
+	ref[last_index] = NULL;
 
 	CurrentSetSize--;
-	ref[fd] = NULL;
 
-	ServerInstance->Logs->Log("SOCKET", DEBUG, "Remove file descriptor: %d", fd);
+	ServerInstance->Logs->Log("SOCKET", DEBUG, "Remove file descriptor: %d (index: %d) "
+			"(Filled gap with: %d (index: %d))", fd, index, last_fd, last_index);
 	return true;
 }
 
@@ -116,7 +163,7 @@ int PollEngine::GetMaxFds()
 	{
 		MAX_DESCRIPTORS = 0;
 		ServerInstance->Logs->Log("SOCKET", DEFAULT, "ERROR: Can't determine maximum number of open sockets: %s", strerror(errno));
-		printf("ERROR: Can't determine maximum number of open sockets: %s\n", strerror(errno)));
+		printf("ERROR: Can't determine maximum number of open sockets: %s\n", strerror(errno));
 		ServerInstance->Exit(EXIT_STATUS_SOCKETENGINE);
 	}
 	return 0;
@@ -144,51 +191,53 @@ int PollEngine::GetRemainingFds()
 
 int PollEngine::DispatchEvents()
 {
-	int i = poll(events, GetMaxFds() - 1, 1000);
-	int fd = 0;
+	int i = poll(events, CurrentSetSize, 1000);
+	int index;
 	socklen_t codesize = sizeof(int);
 	int errcode;
 	int processed = 0;
 
 	if (i > 0)
 	{
-		for (fd = 0; fd < GetMaxFds() - 1 && processed != i; fd++)
+		for (index = 0; index < CurrentSetSize && processed != i; index++)
 		{
-			if (events[fd].revents)
+			if (events[index].revents)
 				processed++;
 
-			if (events[fd].revents & POLLHUP)
+			if (events[index].revents & POLLHUP)
 			{
-				if (ref[fd])
-					ref[fd]->HandleEvent(EVENT_ERROR, 0);
+				if (ref[index])
+					ref[index]->HandleEvent(EVENT_ERROR, 0);
 				continue;
 			}
 
-			if (events[fd].revents & POLLERR)
+			if (events[index].revents & POLLERR)
 			{
+				// Get fd
+				int fd = events[index].fd;
+
 				// Get error number
 				if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &errcode, &codesize) < 0)
 					errcode = errno;
-				if (ref[fd])
-					ref[fd]->HandleEvent(EVENT_ERROR, errcode);
+				if (ref[index])
+					ref[index]->HandleEvent(EVENT_ERROR, errcode);
 				continue;
 			}
 
-			if (events[fd].revents & POLLOUT)
+			if (events[index].revents & POLLOUT)
 			{
 				// Switch to wanting read again
 				// event handlers have to request to write again if they need it
-				events[fd].events = POLLIN;
-
+				events[index].events = POLLIN;
 
-				if (ref[fd])
-					ref[fd]->HandleEvent(EVENT_WRITE);
+				if (ref[index])
+					ref[index]->HandleEvent(EVENT_WRITE);
 			}
 
-			if (events[fd].revents & POLLIN)
+			if (events[index].revents & POLLIN)
 			{
-				if (ref[fd])
-					ref[fd]->HandleEvent(EVENT_READ);
+				if (ref[index])
+					ref[index]->HandleEvent(EVENT_READ);
 			}
 		}
 	}