Added a service that will be responsible for sending messages from kernel

to userland applications. A userland server (probably the registrar) will
register as the server responsible for delivering the messages. The
messages are passed to it via shared memory.

The advantage over sending the messages directly will be, that they won't
need to be dropped, if the receiver port is temporarily full.

Currently only the kernel side is implemented. Completely untested yet.


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@10983 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/kernel/core/Jamfile

@@ -60,5 +60,6 @@ SubInclude OBOS_TOP src kernel core cache ;
 SubInclude OBOS_TOP src kernel core device_manager ;
 SubInclude OBOS_TOP src kernel core disk_device_manager ;
 SubInclude OBOS_TOP src kernel core fs ;
-SubInclude OBOS_TOP src kernel core vm ;
+SubInclude OBOS_TOP src kernel core messaging ;
 SubInclude OBOS_TOP src kernel core util ;
+SubInclude OBOS_TOP src kernel core vm ;

src/kernel/core/messaging/Jamfile

@@ -0,0 +1,15 @@
+SubDir OBOS_TOP src kernel core messaging ;
+
+UsePrivateHeaders [ FDirName kernel ] ;
+#UsePrivateHeaders [ FDirName kernel disk_device_manager ] ;
+#UsePrivateHeaders [ FDirName kernel fs ] ;
+UsePrivateHeaders [ FDirName kernel util ] ;	# for <KMessage.h>
+UsePrivateHeaders shared ;
+UseHeaders [ FDirName $(OBOS_TOP) src kernel core disk_device_manager ] ;
+	# for "Locker.h"
+
+KernelMergeObject kernel_messaging.o :
+	MessagingService.cpp
+
+	: -fno-pic -Wno-unused -D_KERNEL_MODE
+	;

src/kernel/core/messaging/MessagingService.cpp

@@ -0,0 +1,489 @@
+/* 
+ * Copyright 2005, Ingo Weinhold, [email protected]. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+
+// kernel-side implementation of the messaging service
+
+#include <new>
+
+#include <AutoDeleter.h>
+#include <KMessage.h>
+#include <messaging.h>
+#include <MessagingServiceDefs.h>
+
+#include "MessagingService.h"
+
+static MessagingService *sMessagingService = NULL;
+
+static const int32 kMessagingAreaSize = B_PAGE_SIZE * 4;
+
+// init_messaging_service
+status_t
+init_messaging_service()
+{
+	static char buffer[sizeof(MessagingService)];
+
+	if (!sMessagingService)
+		sMessagingService = new(buffer) MessagingService;
+
+	return sMessagingService->InitCheck();
+}
+
+// _user_register_messaging_service
+/** \brief Called by the userland server to register itself as a messaging
+		   service for the kernel.
+	\param lockingSem A semaphore used for locking the shared data. Semaphore
+		   counter must be initialized to 0.
+	\param counterSem A semaphore released every time the kernel pushes a
+		   command. Semaphore counter must be initialized to 0.
+	\return
+	- The ID of the kernel area used for communication, if everything went fine,
+	- an error code otherwise.
+*/
+area_id
+_user_register_messaging_service(sem_id lockSem, sem_id counterSem)
+{
+	// check, if init_messaging_service() has been called yet
+	if (!sMessagingService)
+		return B_NO_INIT;
+
+	if (!sMessagingService->Lock())
+		return B_BAD_VALUE;
+
+	area_id areaID;
+	status_t error = sMessagingService->RegisterService(lockSem, counterSem,
+		areaID);
+
+	sMessagingService->Unlock();
+
+	return (error != B_OK ? error : areaID);
+}
+
+// send_message
+status_t
+send_message(const void *message, int32 messageSize,
+	const messaging_target *targets, int32 targetCount)
+{
+	// check, if init_messaging_service() has been called yet
+	if (!sMessagingService)
+		return B_NO_INIT;
+
+	if (!sMessagingService->Lock())
+		return B_BAD_VALUE;
+
+	status_t error = sMessagingService->SendMessage(message, messageSize,
+		targets, targetCount);
+
+	sMessagingService->Unlock();
+
+	return error;
+}
+
+// send_message
+status_t
+send_message(const KMessage *message, const messaging_target *targets,
+	int32 targetCount)
+{
+	if (!message)
+		return B_BAD_VALUE;
+
+	return send_message(message->Buffer(), message->ContentSize(), targets,
+		targetCount);
+}
+
+
+// #pragma mark -
+
+// constructor
+MessagingArea::MessagingArea()
+{
+}
+
+// destructor
+MessagingArea::~MessagingArea()
+{
+	if (fID >= 0)
+		delete_area(fID);
+}
+
+// Create
+MessagingArea *
+MessagingArea::Create(sem_id lockSem, sem_id counterSem)
+{
+	// allocate the object on the heap
+	MessagingArea *area = new(nothrow) MessagingArea;
+	if (!area)
+		return NULL;
+
+	// create the area
+	area->fID = create_area("messaging", (void**)&area->fHeader,
+		B_ANY_KERNEL_ADDRESS, kMessagingAreaSize, B_FULL_LOCK,
+		B_READ_AREA | B_WRITE_AREA);
+	if (area->fID < 0) {
+		delete area;
+		return NULL;
+	}
+
+	// finish the initialization of the object
+	area->fSize = kMessagingAreaSize;
+	area->fLockSem = lockSem;
+	area->fCounterSem = counterSem;
+	area->fNextArea = NULL;
+	area->InitHeader();
+
+	return area;
+}
+
+// InitHeader
+void
+MessagingArea::InitHeader()
+{
+	fHeader->lock_counter = 1;			// create locked
+	fHeader->size = fSize;
+	fHeader->kernel_area = fID;
+	fHeader->next_kernel_area = (fNextArea ? fNextArea->ID() : -1);
+	fHeader->command_count = 0;
+	fHeader->first_command = 0;
+	fHeader->last_command = 0;
+}
+
+// CheckCommandSize
+bool
+MessagingArea::CheckCommandSize(int32 dataSize)
+{
+	int32 size = sizeof(messaging_command) + dataSize;
+
+	return (dataSize >= 0
+		&& size <= kMessagingAreaSize - (int32)sizeof(messaging_area_header));
+}
+
+// Lock
+bool
+MessagingArea::Lock()
+{
+	// benaphore-like locking
+	if (atomic_add(&fHeader->lock_counter, 1) == 0)
+		return true;
+
+	return (acquire_sem(fLockSem) == B_OK);
+}
+
+// Unlock
+void
+MessagingArea::Unlock()
+{
+	if (atomic_add(&fHeader->lock_counter, -1) > 1)
+		release_sem(fLockSem);
+}
+
+// ID
+area_id
+MessagingArea::ID() const
+{
+	return fID;
+}
+
+// Size
+int32
+MessagingArea::Size() const
+{
+	return fSize;
+}
+
+// AllocateCommand
+void *
+MessagingArea::AllocateCommand(uint32 commandWhat, int32 dataSize)
+{
+	int32 size = sizeof(messaging_command) + dataSize;
+
+	if (dataSize < 0 || size > fSize - (int32)sizeof(messaging_area_header))
+		return NULL;
+
+	// the area is used as a ring buffer
+	int32 startOffset = sizeof(messaging_area_header);
+
+	// the simple case first: the area is empty
+	int32 commandOffset;
+	if (fHeader->command_count == 0) {
+		commandOffset = startOffset;
+
+		// update the header
+		fHeader->command_count++;
+		fHeader->first_command = fHeader->last_command = commandOffset;
+	} else {
+		int32 firstCommandOffset = fHeader->first_command;
+		int32 lastCommandOffset = fHeader->last_command;
+		int32 firstCommandSize;
+		int32 lastCommandSize;
+		messaging_command *firstCommand = _CheckCommand(firstCommandOffset,
+			firstCommandSize);
+		messaging_command *lastCommand = _CheckCommand(lastCommandOffset,
+			lastCommandSize);
+		if (!firstCommand || !lastCommand) {
+			// something has been screwed up
+			return NULL;
+		}
+
+		// find space for the command
+		if (firstCommandOffset < lastCommandOffset) {
+			// not wrapped
+			// try to allocate after the last command
+			if (size <= fSize - (lastCommandOffset + lastCommandSize)) {
+				commandOffset = (lastCommandOffset + lastCommandSize);
+			} else {
+				// is there enough space before the first command?
+				if (size > firstCommandOffset - startOffset)
+					return NULL;
+				commandOffset = startOffset;
+			}
+		} else {
+			// wrapped: we can only allocate between the last and the first
+			// command
+			commandOffset = lastCommandOffset + lastCommandSize;
+			if (size > firstCommandOffset - commandOffset)
+				return NULL;
+		}
+
+		// update the header and the last command
+		fHeader->command_count++;
+		lastCommand->next_command = fHeader->last_command = commandOffset;
+	}
+
+	// init the command
+	messaging_command *command
+		= (messaging_command*)((char*)fHeader + commandOffset);
+	command->next_command = 0;
+	command->command = commandWhat;
+	command->size = size;
+
+	return command->data;
+}
+
+// CommitCommand
+void
+MessagingArea::CommitCommand()
+{
+	// TODO: If invoked while locked, we should supply B_DO_NOT_RESCHEDULE.
+	release_sem(fCounterSem);
+}
+
+// SetNextArea
+void
+MessagingArea::SetNextArea(MessagingArea *area)
+{
+	fNextArea = area;
+	fHeader->next_kernel_area = (fNextArea ? fNextArea->ID() : -1);
+}
+
+// NextArea
+MessagingArea *
+MessagingArea::NextArea() const
+{
+	return fNextArea;
+}
+
+// _CheckCommand
+messaging_command *
+MessagingArea::_CheckCommand(int32 offset, int32 &size)
+{
+	// check offset
+	if (offset < (int32)sizeof(messaging_area_header)
+		|| offset + (int32)sizeof(messaging_command) > fSize
+		|| (offset & 0x3)) {
+		return NULL;
+	}
+
+	// get and check size
+	messaging_command *command = (messaging_command*)((char*)fHeader + offset);
+	size = command->size;
+	if (size < (int32)sizeof(messaging_command))
+		return NULL;
+	size = (size + 3) & 0x3;	// align
+	if (offset + size > fSize)
+		return NULL;
+
+	return command;
+}
+
+
+// #pragma mark -
+
+// constructor
+MessagingService::MessagingService()
+	: fLock("messaging service"),
+	  fFirstArea(NULL),
+	  fLastArea(NULL)
+{
+}
+
+// destructor
+MessagingService::~MessagingService()
+{
+	// Should actually never be called. Once created the service stays till the
+	// bitter end.
+}
+
+// InitCheck
+status_t
+MessagingService::InitCheck() const
+{
+	if (fLock.Sem() < 0)
+		return fLock.Sem();
+	return B_OK;
+}
+
+// Lock
+bool
+MessagingService::Lock()
+{
+	return fLock.Lock();
+}
+
+// Unlock
+void
+MessagingService::Unlock()
+{
+	fLock.Unlock();
+}
+
+// RegisterService
+status_t
+MessagingService::RegisterService(sem_id lockSem, sem_id counterSem,
+	area_id &areaID)
+{
+	// check, if a service is already registered
+	if (fFirstArea)
+		return B_BAD_VALUE;
+
+	status_t error = B_OK;
+
+	// check, if the semaphores are valid and belong to the calling team
+	thread_info threadInfo;
+	error = get_thread_info(find_thread(NULL), &threadInfo);
+
+	sem_info lockSemInfo;
+	if (error == B_OK)
+		error = get_sem_info(lockSem, &lockSemInfo);
+
+	sem_info counterSemInfo;
+	if (error == B_OK)
+		error = get_sem_info(counterSem, &counterSemInfo);
+
+	if (error != B_OK)
+		return error;
+
+	if (threadInfo.team != lockSemInfo.team
+		|| threadInfo.team != counterSemInfo.team) {
+		return B_BAD_VALUE;
+	}
+
+	// create an area
+	fFirstArea = fLastArea = MessagingArea::Create(lockSem, counterSem);
+	if (!fFirstArea)
+		return B_NO_MEMORY;
+
+	areaID = fFirstArea->ID();
+	fFirstArea->Unlock();
+
+	return B_OK;
+}
+
+// SendMessage
+status_t
+MessagingService::SendMessage(const void *message, int32 messageSize,
+	const messaging_target *targets, int32 targetCount)
+{
+	if (!message || messageSize <= 0 || !targets || targetCount <= 0)
+		return B_BAD_VALUE;
+
+	int32 dataSize = sizeof(messaging_command_send_message)
+		+ targetCount * sizeof(messaging_target) + messageSize;
+
+	// allocate space for the command
+	MessagingArea *area;
+	void *data;
+	status_t error = _AllocateCommand(MESSAGING_COMMAND_SEND_MESSAGE, dataSize,
+		area, data);
+	if (error != B_OK)
+		return error;
+
+	// prepare the command
+	messaging_command_send_message *command
+		= (messaging_command_send_message*)data;
+	command->message_size = messageSize;
+	command->target_count = targetCount;
+	memcpy(command->targets, targets, sizeof(messaging_target) * targetCount);
+	memcpy((char*)command + (dataSize - messageSize), message, messageSize);
+
+	// shoot
+	area->Unlock();
+	area->CommitCommand();
+
+	return B_OK;
+}
+
+// _AllocateCommand
+status_t
+MessagingService::_AllocateCommand(int32 commandWhat, int32 size,
+	MessagingArea *&area, void *&data)
+{
+	if (!fFirstArea)
+		return B_NO_INIT;
+
+	if (!MessagingArea::CheckCommandSize(size))
+		return B_BAD_VALUE;
+
+	// delete the discarded areas (save one)
+	ObjectDeleter<MessagingArea> discardedAreaDeleter;
+	MessagingArea *discardedArea = NULL;
+	while (fFirstArea != fLastArea) {
+		area = fFirstArea;
+		area->Lock();
+		if (area->Size() != 0) {
+			area->Unlock();
+			break;
+		}
+
+		fFirstArea = area->NextArea();
+		area->SetNextArea(NULL);
+		discardedArea = area;
+		discardedAreaDeleter.SetTo(area);
+	}
+
+	// allocate space for the command in the last area
+	area = fLastArea;
+	area->Lock();
+	data = area->AllocateCommand(commandWhat, size);
+
+	if (!data) {
+		// not enough space in the last area: create a new area or reuse a
+		// discarded one
+		if (discardedArea) {
+			area = discardedAreaDeleter.Detach();
+			area->InitHeader();
+		} else
+			area = MessagingArea::Create(fLockSem, fCounterSem);
+		if (!area) {
+			fLastArea->Unlock();
+			return B_NO_MEMORY;
+		}
+
+		// add the new area
+		fLastArea->SetNextArea(area);
+		fLastArea->Unlock();
+		fLastArea = area;
+
+		// allocate space for the command
+		data = area->AllocateCommand(commandWhat, size);
+
+		if (!data) {
+			// that should never happen
+			area->Unlock();
+			return B_NO_MEMORY;
+		}
+	}
+
+	return B_OK;
+}
+

src/kernel/core/messaging/MessagingService.h

@@ -0,0 +1,86 @@
+/* 
+ * Copyright 2005, Ingo Weinhold, [email protected]. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+
+// kernel-side implementation-private definitions for the messaging service
+
+#ifndef MESSAGING_SERVICE_H
+#define MESSAGING_SERVICE_H
+
+#include <MessagingServiceDefs.h>
+
+#include "Locker.h"
+
+namespace BPrivate {
+
+// MessagingArea
+class MessagingArea : public messaging_area_header {
+public:
+	~MessagingArea();
+
+	static MessagingArea *Create(sem_id lockSem, sem_id counterSem);
+
+	static bool CheckCommandSize(int32 dataSize);
+
+	void InitHeader();
+
+	bool Lock();
+	void Unlock();
+
+	area_id ID() const;
+	int32 Size() const;
+
+	void *AllocateCommand(uint32 commandWhat, int32 dataSize);
+	void CommitCommand();
+
+	void SetNextArea(MessagingArea *area);
+	MessagingArea *NextArea() const;
+
+private:
+	MessagingArea();
+
+	messaging_command *_CheckCommand(int32 offset, int32 &size);
+
+	messaging_area_header	*fHeader;
+	area_id					fID;
+	int32					fSize;
+	sem_id					fLockSem;
+	sem_id					fCounterSem;
+	MessagingArea			*fNextArea;
+};
+
+// MessagingService
+class MessagingService {
+public:
+	MessagingService();
+	~MessagingService();
+
+	status_t InitCheck() const;
+
+	bool Lock();
+	void Unlock();
+
+	status_t RegisterService(sem_id lockingSem, sem_id counterSem,
+		area_id &areaID);
+
+	status_t SendMessage(const void *message, int32 messageSize,
+		const messaging_target *targets, int32 targetCount);
+
+private:
+	status_t _AllocateCommand(int32 commandWhat, int32 size,
+		MessagingArea *&area, void *&data);
+
+	BLocker			fLock;
+	sem_id			fLockSem;
+	sem_id			fCounterSem;
+	MessagingArea	*fFirstArea;
+	MessagingArea	*fLastArea;
+};
+
+}	// namespace BPrivate
+
+using BPrivate::MessagingArea;
+using BPrivate::MessagingService;
+
+#endif	// MESSAGING_SERVICE_H