RMsgQueue Class Reference

#include <e32msgqueue.h>

class RMsgQueue : public RMsgQueueBase

Inherits from

RMsgQueue
- RMsgQueueBase
  - RHandleBase

Public Member Functions
TInt	CreateGlobal(const TDesC &, TInt, TOwnerType)
TInt	CreateLocal(TInt, TOwnerType)
TInt	Receive(T &)
void	ReceiveBlocking(T &)
TInt	Send(const T &)
void	SendBlocking(const T &)

Inherited Attributes
	RHandleBase::iHandle

Inherited Enumerations
	RHandleBase:TAttributes
	RMsgQueueBase:@277

Inherited Functions
	RHandleBase::Attributes()const
	RHandleBase::BTraceId()const
	RHandleBase::Close()
	RHandleBase::DoExtendedClose()
	RHandleBase::Duplicate(const RThread &,TOwnerType)
	RHandleBase::FullName()const
	RHandleBase::FullName(TDes &)const
	RHandleBase::Handle()const
	RHandleBase::HandleInfo(THandleInfo *)
	RHandleBase::Name()const
	RHandleBase::NotifyDestruction(TRequestStatus &)
	RHandleBase::Open(const TFindHandleBase &,TOwnerType)
	RHandleBase::OpenByName(const TDesC &,TOwnerType,TInt)
	RHandleBase::RHandleBase()
	RHandleBase::RHandleBase(TInt)
	RHandleBase::SetHandle(TInt)
	RHandleBase::SetHandleNC(TInt)
	RHandleBase::SetReturnedHandle(TInt)
	RHandleBase::SetReturnedHandle(TInt,RHandleBase &)
	RMsgQueueBase::CancelDataAvailable()
	RMsgQueueBase::CancelSpaceAvailable()
	RMsgQueueBase::CreateGlobal(const TDesC &,TInt,TInt,TOwnerType)
	RMsgQueueBase::CreateLocal(TInt,TInt,TOwnerType)
	RMsgQueueBase::MessageSize()
	RMsgQueueBase::NotifyDataAvailable(TRequestStatus &)
	RMsgQueueBase::NotifySpaceAvailable(TRequestStatus &)
	RMsgQueueBase::Open(RMessagePtr2,TInt,TOwnerType)
	RMsgQueueBase::Open(TInt,TOwnerType)
	RMsgQueueBase::OpenGlobal(const TDesC &,TOwnerType)
	RMsgQueueBase::Receive(TAny *,TInt)
	RMsgQueueBase::ReceiveBlocking(TAny *,TInt)
	RMsgQueueBase::Send(const TAny *,TInt)
	RMsgQueueBase::SendBlocking(const TAny *,TInt)

Detailed Description

A handle to a message queue.

The templated class provides the behaviour for managing an asynchronous queue of messages, where the template parameter defines the message type.

The class adds a type-checking interface to the basic message queue functionality provided by RMsgQueueBase.

Member Function Documentation

CreateGlobal ( const TDesC &, TInt, TOwnerType )

TInt	CreateGlobal	(	const TDesC &	aName,
			TInt	aSize,
			TOwnerType	aType = EOwnerProcess
		)	[inline]

Creates a global message queue, and opens a handle to that message queue.

If the name is non-empty, the message queue is visible to all processes. If the name is empty it cannot be opened or searched for by name, but a handle to it can be passed to another process as a process parameter or via IPC.

The size of each message in the queue is the size of the template parameter type. This must conform to the restrictions imposed on the aMsgLength parameter passed to the base class function RMsgQueueBase::CreateGlobal().

Parameters
aName	The name to be assigned to the message queue.
aSize	The number of message 'slots' in the queue. This must be a positive value, i.e. greater than zero.
aType	The type of handle to be created. EOwnerProcess is the default value, if not explicitly specified.

Return Value: KErrNone if the queue is created sucessfully, otherwise one of the other system wide error codes.

Panic Codes
KERN-EXEC	49 if aSize is less than or equal to zero.
KERN-EXEC	48 if the size of the template parameter type is not a multiple of 4 bytes, is less than 4, or is greater than KMaxLength.

CreateLocal ( TInt, TOwnerType )

TInt	CreateLocal	(	TInt	aSize,
			TOwnerType	aType = EOwnerProcess
		)	[inline]

Creates a message queue that is private to the current process, and opens a handle to that message queue.

Parameters
aSize	The number of message 'slots' in the queue. This must be a positive value, i.e. greater than zero.
aType	The type of handle to be created. EOwnerProcess is the default value, if not explicitly specified.

Return Value: KErrNone if the queue is created sucessfully, otherwise one of the other system wide error codes.

Panic Codes
KERN-EXEC	49 if aSize is less than or equal to zero.
KERN-EXEC	48 if the size of the template parameter type is not a multiple of 4 bytes, is less than 4, or is greater than KMaxLength.

Receive ( T & )

TInt

Receive

(

T &

aMsg

)

[inline]

Retrieves the first message in the queue.

The function does not wait (i.e. block), if the queue is empty.

The function is implemented through a call to RMsgQueueBase::Receive().

ReceiveBlocking ( T & )

void

ReceiveBlocking

(

T &

aMsg

)

[inline]

Retrieves the first message in the queue, and waits if the queue is empty.

The function uses NotifyDataAvailable() to provide the blocking operation. Note it is not possible to cancel a call to ReceiveBlocking().

The function is implemented through a call to RMsgQueueBase::ReceiveBlocking().

Parameters
aMsg	The object into which the message is retrieved.

Send ( const T & )

TInt

Send

(

const T &

aMsg

)

[inline]

Sends a message through this queue.

The function does not wait (i.e. block), if the queue is full.

The function is implemented through a call to RMsgQueueBase::Send().

Parameters
aMsg	The message data to be sent.

SendBlocking ( const T & )

void

SendBlocking

(

const T &

aMsg

)

[inline]

Sends a message through this queue, and waits for space to become available if the queue is full.

The function uses NotifySpaceAvailable() to provide the blocking operation. Note that it is not possible to cancel a call to SendBlocking().

The function is implemented through a call to RMsgQueueBase::SendBlocking().