/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 2002
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Darin Fisher <darin@netscape.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#ifndef nsSocketTransportService2_h__
#define nsSocketTransportService2_h__

#include "nsPISocketTransportService.h"
#include "nsIEventTarget.h"
#include "nsIRunnable.h"
#include "nsIThread.h"
#include "nsCOMPtr.h"
#include "pldhash.h"
#include "prinrval.h"
#include "prlog.h"
#include "prio.h"

//-----------------------------------------------------------------------------

#if defined(PR_LOGGING)
//
// set NSPR_LOG_MODULES=nsSocketTransport:5
//
extern PRLogModuleInfo *gSocketTransportLog;
#endif
#define LOG(args)     PR_LOG(gSocketTransportLog, PR_LOG_DEBUG, args)
#define LOG_ENABLED() PR_LOG_TEST(gSocketTransportLog, PR_LOG_DEBUG)

//-----------------------------------------------------------------------------

#define NS_SOCKET_MAX_COUNT    50
#define NS_SOCKET_POLL_TIMEOUT PR_INTERVAL_NO_TIMEOUT

//-----------------------------------------------------------------------------
// socket handler: methods are only called on the socket thread.

class nsASocketHandler : public nsISupports
{
public:
    nsASocketHandler()
        : mCondition(NS_OK)
        , mPollFlags(0)
        , mPollTimeout(PR_UINT16_MAX)
        {}

    //
    // this condition variable will be checked to determine if the socket
    // handler should be detached.  it must only be accessed on the socket
    // thread.
    //
    nsresult mCondition;

    //
    // these flags can only be modified on the socket transport thread.
    // the socket transport service will check these flags before calling
    // PR_Poll.
    //
    PRUint16 mPollFlags;

    //
    // this value specifies the maximum amount of time in seconds that may be
    // spent waiting for activity on this socket.  if this timeout is reached,
    // then OnSocketReady will be called with outFlags = -1.
    //
    // the default value for this member is PR_UINT16_MAX, which disables the
    // timeout error checking.  (i.e., a timeout value of PR_UINT16_MAX is
    // never reached.)
    //
    PRUint16 mPollTimeout;

    //
    // called to service a socket
    // 
    // params:
    //   socketRef - socket identifier
    //   fd        - socket file descriptor
    //   outFlags  - value of PR_PollDesc::out_flags after PR_Poll returns
    //               or -1 if a timeout occured
    //
    virtual void OnSocketReady(PRFileDesc *fd, PRInt16 outFlags) = 0;

    //
    // called when a socket is no longer under the control of the socket
    // transport service.  the socket handler may close the socket at this
    // point.  after this call returns, the handler will no longer be owned
    // by the socket transport service.
    //
    virtual void OnSocketDetached(PRFileDesc *fd) = 0;
};

//-----------------------------------------------------------------------------

class nsSocketTransportService : public nsPISocketTransportService
                               , public nsIEventTarget
                               , public nsIRunnable
{
public:
    NS_DECL_ISUPPORTS
    NS_DECL_NSPISOCKETTRANSPORTSERVICE
    NS_DECL_NSISOCKETTRANSPORTSERVICE
    NS_DECL_NSIEVENTTARGET
    NS_DECL_NSIRUNNABLE

    nsSocketTransportService();

    //
    // the number of sockets that can be attached at any given time is
    // limited.  this is done because some operating systems (e.g., Win9x)
    // limit the number of sockets that can be created by an application.
    // AttachSocket will fail if the limit is exceeded.  consumers should
    // call CanAttachSocket and check the result before creating a socket.
    //
    PRBool CanAttachSocket() { return mActiveCount + mIdleCount < NS_SOCKET_MAX_COUNT; }

    //
    // if the number of sockets is at the limit, then consumers can be notified
    // when the number of sockets becomes less than the limit.  the notification
    // is asynchronous, delivered via the given PLEvent instance on the socket
    // transport thread.
    //
    nsresult NotifyWhenCanAttachSocket(PLEvent *);

    //
    // add a new socket to the list of controlled sockets.  returns a socket
    // reference for the newly attached socket that can be used with other
    // methods to control the socket.
    //
    // NOTE: this function may only be called from an event dispatch on the
    //       socket thread.
    //
    nsresult AttachSocket(PRFileDesc *fd, nsASocketHandler *);

protected:

    virtual ~nsSocketTransportService();

private:

    //-------------------------------------------------------------------------
    // misc (any thread)
    //-------------------------------------------------------------------------

    PRBool      mInitialized;
    nsIThread  *mThread;
    PRFileDesc *mThreadEvent;
                            // protected by mEventQLock.  mThreadEvent may
                            // change if the old pollable event is broken.
                            // only the socket thread may change mThreadEvent;
                            // it needs to lock mEventQLock only when it
                            // changes mThreadEvent.  other threads don't
                            // change mThreadEvent; they need to lock
                            // mEventQLock whenever they access mThreadEvent.

    // pref to control autodial code
    PRBool      mAutodialEnabled;

    //-------------------------------------------------------------------------
    // misc (socket thread only)
    //-------------------------------------------------------------------------
    // indicates whether we are currently in the process of shutting down
    PRBool      mShuttingDown;

    //-------------------------------------------------------------------------
    // event queue (any thread)
    //-------------------------------------------------------------------------

    PRCList  mEventQ; // list of PLEvent objects
    PRLock  *mEventQLock;

    //-------------------------------------------------------------------------
    // socket lists (socket thread only)
    //
    // only "active" sockets are on the poll list.  the active list is kept
    // in sync with the poll list such that:
    //
    //   mActiveList[k].mFD == mPollList[k+1].fd
    //
    // where k=0,1,2,...
    //-------------------------------------------------------------------------

    struct SocketContext
    {
        PRFileDesc       *mFD;
        nsASocketHandler *mHandler;
        PRUint16          mElapsedTime;  // time elapsed w/o activity
    };

    SocketContext mActiveList [ NS_SOCKET_MAX_COUNT ];
    SocketContext mIdleList   [ NS_SOCKET_MAX_COUNT ];

    PRUint32 mActiveCount;
    PRUint32 mIdleCount;

    nsresult DetachSocket(SocketContext *);
    nsresult AddToIdleList(SocketContext *);
    nsresult AddToPollList(SocketContext *);
    void RemoveFromIdleList(SocketContext *);
    void RemoveFromPollList(SocketContext *);
    void MoveToIdleList(SocketContext *sock);
    void MoveToPollList(SocketContext *sock);
    
    // returns PR_FALSE to stop processing the main loop
    PRBool ServiceEventQ();

    //-------------------------------------------------------------------------
    // poll list (socket thread only)
    //
    // first element of the poll list is mThreadEvent (or null if the pollable
    // event cannot be created).
    //-------------------------------------------------------------------------

    PRPollDesc mPollList[ NS_SOCKET_MAX_COUNT + 1 ];

    PRIntervalTime PollTimeout();            // computes ideal poll timeout
    PRInt32        Poll(PRUint32 *interval); // calls PR_Poll.  the out param
                                             // interval indicates the poll
                                             // duration in seconds.

    //-------------------------------------------------------------------------
    // pending socket queue - see NotifyWhenCanAttachSocket
    //-------------------------------------------------------------------------

    PRCList mPendingSocketQ; // list of PLEvent objects
};

extern nsSocketTransportService *gSocketTransportService;
extern PRThread                 *gSocketThread;

#endif // !nsSocketTransportService_h__
