Modified cRingBufferLinear to avoid excessive memmove() calls in 'Transfer Mode' and during recordings

CONTRIBUTORS

@@ -530,3 +530,4 @@ Teemu Rantanen <tvr@iki.fi>
  for increased the maximum possible packet size in remux.c to avoid corrupted streams
  with broadcasters that send extremely large PES packets
  for adding TS error checking to remux.c
+ for pinpointing a problem with excessive memmove() calls in 'Transfer Mode'

HISTORY

@@ -1917,7 +1917,7 @@ Video Disk Recorder Revision History
   EPG data, that string is now limited in length when used in a recording's
   file name.
 
-2003-01-24: Version 1.1.22
+2003-01-25: Version 1.1.22
 
 - Added 'Hrvatska radiotelevizija' and 'RTV Slovenija' to ca.conf (thanks to
   Paul Gohn).
@@ -1928,3 +1928,6 @@ Video Disk Recorder Revision History
 - Increased the maximum possible packet size in remux.c to avoid corrupted streams
   with broadcasters that send extremely large PES packets (thanks to Teemu Rantanen).
 - Added TS error checking to remux.c (thanks to Teemu Rantanen).
+- Modified cRingBufferLinear to avoid excessive memmove() calls in 'Transfer Mode'
+  and during recordings, which dramatically reduces CPU load. Thanks to Teemu
+  Rantanen for pinpointing the problem with the excessive memmove() calls.

recorder.c

@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: recorder.c 1.4 2002/12/22 11:33:08 kls Exp $
+ * $Id: recorder.c 1.5 2003/01/25 16:23:36 kls Exp $
  */
 
 #include <stdarg.h>
@@ -41,7 +41,7 @@ cRecorder::cRecorder(const char *FileName, int Ca, int Priority, int VPid, int A
 
   SpinUpDisk(FileName);
 
-  ringBuffer = new cRingBufferLinear(VIDEOBUFSIZE, true);
+  ringBuffer = new cRingBufferLinear(VIDEOBUFSIZE, TS_SIZE * 2, true);
   remux = new cRemux(VPid, APid1, APid2, DPid1, DPid2, true);
   fileName = new cFileName(FileName, true);
   recordFile = fileName->Open();
@@ -110,16 +110,14 @@ void cRecorder::Action(void)
 {
   dsyslog("recording thread started (pid=%d)", getpid());
 
-  uchar b[MINVIDEODATA];
-  int r = 0;
   active = true;
   while (active) {
-        int g = ringBuffer->Get(b + r, sizeof(b) - r);
+        int r;
-        if (g > 0)
+        const uchar *b = ringBuffer->Get(r);
-           r += g;
+        if (b) {
-        if (r > 0) {
            int Count = r, Result;
            uchar *p = remux->Process(b, Count, Result, &pictureType);
+           ringBuffer->Del(Count);
            if (p) {
               //XXX+ active??? see old version (Busy)
               if (!active && pictureType == I_FRAME) // finish the recording before the next 'I' frame
@@ -136,10 +134,6 @@ void cRecorder::Action(void)
               else
                  break;
               }
-           if (Count > 0) {
-              r -= Count;
-              memmove(b, b + Count, r);
-              }
            }
         else
            usleep(1); // this keeps the CPU load low

ringbuffer.c

@@ -7,7 +7,7 @@
  * Parts of this file were inspired by the 'ringbuffy.c' from the
  * LinuxDVB driver (see linuxtv.org).
  *
- * $Id: ringbuffer.c 1.11 2003/01/19 15:03:00 kls Exp $
+ * $Id: ringbuffer.c 1.12 2003/01/26 09:39:24 kls Exp $
  */
 
 #include "ringbuffer.h"
@@ -57,13 +57,14 @@ void cRingBuffer::EnableGet(void)
 
 // --- cRingBufferLinear -----------------------------------------------------
 
-cRingBufferLinear::cRingBufferLinear(int Size, bool Statistics)
+cRingBufferLinear::cRingBufferLinear(int Size, int Margin, bool Statistics)
 :cRingBuffer(Size, Statistics)
 {
+  margin = Margin;
   buffer = NULL;
   getThreadPid = -1;
   if (Size > 1) { // 'Size - 1' must not be 0!
-     buffer = new uchar[Size];
+     buffer = MALLOC(uchar, Size);
      if (!buffer)
         esyslog("ERROR: can't allocate ring buffer (size=%d)", Size);
      Clear();
@@ -74,7 +75,7 @@ cRingBufferLinear::cRingBufferLinear(int Size, bool Statistics)
 
 cRingBufferLinear::~cRingBufferLinear()
 {
-  delete buffer;
+  free(buffer);
 }
 
 int cRingBufferLinear::Available(void)
@@ -82,13 +83,14 @@ int cRingBufferLinear::Available(void)
   Lock();
   int diff = head - tail;
   Unlock();
-  return (diff >= 0) ? diff : Size() + diff;
+  return (diff >= 0) ? diff : Size() + diff - margin;
 }
 
 void cRingBufferLinear::Clear(void)
 {
   Lock();
-  head = tail = 0;
+  head = tail = margin;
+  lastGet = -1;
   Unlock();
   EnablePut();
   EnableGet();
@@ -100,7 +102,7 @@ int cRingBufferLinear::Put(const uchar *Data, int Count)
      Lock();
      int rest = Size() - head;
      int diff = tail - head;
-     int free = (diff > 0) ? diff - 1 : Size() + diff - 1;
+     int free = (diff > 0) ? diff - 1 : Size() + diff - (tail < margin ? -(margin - tail) : margin) - 1;
      if (statistics) {
         int fill = Size() - free - 1 + Count;
         if (fill >= Size())
@@ -122,8 +124,8 @@ int cRingBufferLinear::Put(const uchar *Data, int Count)
         if (Count >= rest) {
            memcpy(buffer + head, Data, rest);
            if (Count - rest)
-              memcpy(buffer, Data + rest, Count - rest);
+              memcpy(buffer + margin, Data + rest, Count - rest);
-           head = Count - rest;
+           head = margin + Count - rest;
            }
         else {
            memcpy(buffer + head, Data, Count);
@@ -138,36 +140,42 @@ int cRingBufferLinear::Put(const uchar *Data, int Count)
   return Count;
 }
 
-int cRingBufferLinear::Get(uchar *Data, int Count)
+const uchar *cRingBufferLinear::Get(int &Count)
 {
-  if (Count > 0) {
+  const uchar *p = NULL;
-     Lock();
+  Lock();
-     if (getThreadPid < 0)
+  if (getThreadPid < 0)
-        getThreadPid = getpid();
+     getThreadPid = getpid();
-     int rest = Size() - tail;
+  int rest = Size() - tail;
-     int diff = head - tail;
+  if (tail > Size() - margin && head < tail) {
-     int cont = (diff >= 0) ? diff : Size() + diff;
+     int t = margin - rest;
-     if (rest > 0) {
+     memcpy(buffer + t, buffer + tail, rest);
-        if (cont < Count)
+     tail = t;
-           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;
-           }
-        }
-     else
-        Count = 0;
-     Unlock();
-     if (Count == 0)
-        WaitForGet();
      }
-  return Count;
+  int diff = head - tail;
+  int cont = (diff >= 0) ? diff : Size() + diff - margin;
+  if (cont > rest)
+     cont = rest;
+  if (cont >= margin) {
+     p = buffer + tail;
+     Count = lastGet = cont;
+     }
+  Unlock();
+  if (!p)
+     WaitForGet();
+  return p;
+}
+
+void cRingBufferLinear::Del(int Count)
+{
+  if (Count > 0 && Count <= lastGet) {
+     tail += Count;
+     lastGet -= Count;
+     if (tail >= Size())
+        tail = margin;
+     }
+  else
+     esyslog("ERROR: invalid Count in cRingBufferLinear::Del: %d", Count);
 }
 
 // --- cFrame ----------------------------------------------------------------

ringbuffer.h

@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: ringbuffer.h 1.8 2003/01/19 15:03:00 kls Exp $
+ * $Id: ringbuffer.h 1.9 2003/01/26 09:47:39 kls Exp $
  */
 
 #ifndef __RINGBUFFER_H
@@ -40,21 +40,31 @@ public:
 
 class cRingBufferLinear : public cRingBuffer {
 private:
-  int head, tail;
+  int margin, head, tail;
+  int lastGet;
   uchar *buffer;
   pid_t getThreadPid;
 public:
-  cRingBufferLinear(int Size, bool Statistics = false);
+  cRingBufferLinear(int Size, int Margin = 0, bool Statistics = false);
+    ///< Creates a linear ring buffer.
+    ///< The buffer will be able to hold at most Size bytes of data, and will
+    ///< be guaranteed to return at least Margin bytes in one consecutive block.
   virtual ~cRingBufferLinear();
   virtual int Available(void);
   virtual void Clear(void);
-    // Immediately clears the ring buffer.
+    ///< Immediately clears the ring buffer.
   int Put(const uchar *Data, int Count);
-    // Puts at most Count bytes of Data into the ring buffer.
+    ///< Puts at most Count bytes of Data into the ring buffer.
-    // Returns the number of bytes actually stored.
+    ///< \return Returns the number of bytes actually stored.
-  int Get(uchar *Data, int Count);
+  const uchar *Get(int &Count);
-    // Gets at most Count bytes of Data from the ring buffer.
+    ///< Gets data from the ring buffer.
-    // Returns the number of bytes actually retrieved.
+    ///< The data will remain in the buffer until a call to Del() deletes it.
+    ///< \return Returns a pointer to the data, and stores the number of bytes
+    ///< actually retrieved in Count. If the returned pointer is NULL, Count has no meaning.
+  void Del(int Count);
+    ///< Deletes at most Count bytes from the ring buffer.
+    ///< Count must be less or equal to the number that was returned by a previous
+    ///< call to Get().
   };
 
 enum eFrameType { ftUnknown, ftVideo, ftAudio, ftDolby };

transfer.c

@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: transfer.c 1.8 2002/12/14 13:14:53 kls Exp $
+ * $Id: transfer.c 1.9 2003/01/26 09:59:35 kls Exp $
  */
 
 #include "transfer.h"
@@ -19,7 +19,7 @@
 cTransfer::cTransfer(int VPid, int APid1, int APid2, int DPid1, int DPid2)
 :cReceiver(0, -1, 5, VPid, APid1, APid2, DPid1, DPid2)
 {
-  ringBuffer = new cRingBufferLinear(VIDEOBUFSIZE, true);
+  ringBuffer = new cRingBufferLinear(VIDEOBUFSIZE, TS_SIZE * 2, true);
   remux = new cRemux(VPid, APid1, APid2, DPid1, DPid2);
   canToggleAudioTrack = false;
   audioTrack = 0xC0;
@@ -60,8 +60,6 @@ void cTransfer::Action(void)
 {
   dsyslog("transfer thread started (pid=%d)", getpid());
 
-  uchar b[MINVIDEODATA];
-  int r = 0;
   active = true;
   while (active) {
 
@@ -80,15 +78,15 @@ void cTransfer::Action(void)
 
         // Get data from the buffer:
 
-        int g = ringBuffer->Get(b + r, sizeof(b) - r);
+        int r;
-        if (g > 0)
+        const uchar *b = ringBuffer->Get(r);
-           r += g;
 
         // Play the data:
 
-        if (r > 0) {
+        if (b) {
            int Count = r, Result;
            uchar *p = remux->Process(b, Count, Result);
+           ringBuffer->Del(Count);
            if (p) {
               StripAudioPackets(p, Result, audioTrack);
               while (Result > 0 && active) {
@@ -103,11 +101,6 @@ void cTransfer::Action(void)
                        }
                     }
               }
-           if (Count > 0) {
-              r -= Count;
-              if (r > 0)
-                 memmove(b, b + Count, r);
-              }
            }
         else
            usleep(1); // this keeps the CPU load low