vdr/ringbuffer.c

/*
 * ringbuffer.c: A threaded ring buffer
 *
 * See the main source file 'vdr.c' for copyright information and
 * how to reach the author.
 *
 * Parts of this file were inspired by the 'ringbuffy.c' from the
 * LinuxDVB driver (see linuxtv.org).
 *
 * $Id: ringbuffer.c 1.4 2001/08/05 12:17:45 kls Exp $
 */

#include "ringbuffer.h"
#include "tools.h"

// --- cRingBufferInputThread -------------------------------------------------

class cRingBufferInputThread : public cThread {
private:
  cRingBuffer *ringBuffer;
protected:
  virtual void Action(void) { ringBuffer->Input(); }
public:
  cRingBufferInputThread(cRingBuffer *RingBuffer) { ringBuffer = RingBuffer; }
  };

// --- cRingBufferOutputThread ------------------------------------------------

class cRingBufferOutputThread : public cThread {
private:
  cRingBuffer *ringBuffer;
protected:
  virtual void Action(void) { ringBuffer->Output(); }
public:
  cRingBufferOutputThread(cRingBuffer *RingBuffer) { ringBuffer = RingBuffer; }
  };

// --- cRingBuffer ------------------------------------------------------------

cRingBuffer::cRingBuffer(int Size, bool Statistics)
{
  size = Size;
  statistics = Statistics;
  inputThread = NULL;
  outputThread = NULL;
  busy = false;
  maxFill = 0;
}

cRingBuffer::~cRingBuffer()
{
  delete inputThread;
  delete outputThread;
  if (statistics)
     dsyslog(LOG_INFO, "buffer stats: %d (%d%%) used", maxFill, maxFill * 100 / (size - 1));
}

void cRingBuffer::WaitForPut(void)
{
  putMutex.Lock();
  readyForPut.Wait(putMutex);
  putMutex.Unlock();
}

void cRingBuffer::WaitForGet(void)
{
  getMutex.Lock();
  readyForGet.Wait(getMutex);
  getMutex.Unlock();
}

void cRingBuffer::EnablePut(void)
{
  readyForPut.Broadcast();
}

void cRingBuffer::EnableGet(void)
{
  readyForGet.Broadcast();
}

bool cRingBuffer::Start(void)
{
  if (!busy) {
     busy = true;
     outputThread = new cRingBufferOutputThread(this);
     if (!outputThread->Start())
        DELETENULL(outputThread);
     inputThread = new cRingBufferInputThread(this);
     if (!inputThread->Start()) {
        DELETENULL(inputThread);
        DELETENULL(outputThread);
        }
     busy = outputThread && inputThread;
     }
  return busy;
}

bool cRingBuffer::Active(void)
{
  return outputThread && outputThread->Active() && inputThread && inputThread->Active();
}

void cRingBuffer::Stop(void)
{
  busy = false;
  for (time_t t0 = time(NULL) + 3; time(NULL) < t0; ) {
      if (!((outputThread && outputThread->Active()) || (inputThread && inputThread->Active())))
         break;
      }
  DELETENULL(inputThread);
  DELETENULL(outputThread);
}

// --- cRingBufferLinear ----------------------------------------------------

cRingBufferLinear::cRingBufferLinear(int Size, bool Statistics)
:cRingBuffer(Size, Statistics)
{
  buffer = NULL;
  if (Size > 1) { // 'Size - 1' must not be 0!
     buffer = new uchar[Size];
     if (!buffer)
        esyslog(LOG_ERR, "ERROR: can't allocate ring buffer (size=%d)", Size);
     Clear();
     }
  else
     esyslog(LOG_ERR, "ERROR: illegal size for ring buffer (%d)", Size);
}

cRingBufferLinear::~cRingBufferLinear()
{
  delete buffer;
}

int cRingBufferLinear::Available(void)
{
  Lock();
  int diff = head - tail;
  Unlock();
  return (diff >= 0) ? diff : Size() + diff;
}

void cRingBufferLinear::Clear(void)
{
  Lock();
  head = tail = 0;
  Unlock();
}

int cRingBufferLinear::Put(const uchar *Data, int Count)
{
  if (Count > 0) {
     Lock();
     int rest = Size() - head;
     int diff = tail - head;
     Unlock();
     int free = (diff > 0) ? diff - 1 : Size() + diff - 1;
     if (statistics) {
        int fill = Size() - free - 1 + Count;
        if (fill >= Size())
           fill = Size() - 1;
        if (fill > maxFill) {
           maxFill = fill;
           int percent = maxFill * 100 / (Size() - 1);
           if (percent > 75)
              dsyslog(LOG_INFO, "buffer usage: %d%%", percent);
           }
        }
     if (free <= 0)
        return 0;
     if (free < Count)
        Count = free;
     if (Count > maxFill)
        maxFill = Count;
     if (Count >= rest) {
        memcpy(buffer + head, Data, rest);
        if (Count - rest)
           memcpy(buffer, Data + rest, Count - rest);
        head = Count - rest;
        }
     else {
        memcpy(buffer + head, Data, Count);
        head += Count;
        }
     }
  return Count;
}

int cRingBufferLinear::Get(uchar *Data, int Count)
{
  if (Count > 0) {
     Lock();
     int rest = Size() - tail;
     int diff = head - tail;
     Unlock();
     int cont = (diff >= 0) ? diff : Size() + diff;
     if (rest <= 0)
        return 0;
     if (cont < Count)
        Count = cont;
     if (Count >= rest) {
        memcpy(Data, buffer + tail, rest);
        if (Count - rest)
           memcpy(Data + rest, buffer, Count - rest);
        tail = Count - rest;
        }
     else {
        memcpy(Data, buffer + tail, Count);
        tail += Count;
        }
     }
  return Count;
}

// --- cFrame ----------------------------------------------------------------

cFrame::cFrame(const uchar *Data, int Count, int Index)
{
  count = Count;
  index = Index;
  data = new uchar[count];
  if (data)
     memcpy(data, Data, count);
  else
     esyslog(LOG_ERR, "ERROR: can't allocate frame buffer (count=%d)", count);
  next = NULL;
}

cFrame::~cFrame()
{
  delete data;
}

// --- cRingBufferFrame ------------------------------------------------------

cRingBufferFrame::cRingBufferFrame(int Size, bool Statistics = false)
:cRingBuffer(Size, Statistics)
{
  head = NULL;
  currentFill = 0;
}

cRingBufferFrame::~cRingBufferFrame()
{
  Clear();
}

void cRingBufferFrame::Clear(void)
{
  Lock();
  const cFrame *p;
  while ((p = Get(false)) != NULL)
        Drop(p);
  Unlock();
  EnablePut();
  EnableGet();
}

bool cRingBufferFrame::Put(cFrame *Frame)
{
  if (Frame->Count() <= Free()) {
     Lock();
     if (head) {
        Frame->next = head->next;
        head->next = Frame;
        head = Frame;
        }
     else {
        head = Frame->next = Frame;
        }
     currentFill += Frame->Count();
     Unlock();
     EnableGet();
     return true;
     }
  WaitForPut();
  return false;
}

const cFrame *cRingBufferFrame::Get(bool Wait)
{
  Lock();
  cFrame *p = head ? head->next : NULL;
  Unlock();
  if (!p && Wait)
     WaitForGet();
  return p;
}

void cRingBufferFrame::Delete(const cFrame *Frame)
{
  currentFill -= Frame->Count();
  delete Frame;
}

void cRingBufferFrame::Drop(const cFrame *Frame)
{
  Lock();
  if (head) {
     if (Frame == head->next) {
        if (head->next != head) {
           head->next = Frame->next;
           Delete(Frame);
           }
        else {
           Delete(head);
           head = NULL;
           }
        }
     else
        esyslog(LOG_ERR, "ERROR: attempt to drop wrong frame from ring buffer!");
     }
  Unlock();
  EnablePut();
}

int cRingBufferFrame::Available(void)
{
  Lock();
  int av = currentFill;
  Unlock();
  return av;
}