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Code Issues Releases Wiki Activity

Improved thread locking in the ring buffer to avoid possible race conditions under heavy load

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This commit is contained in:
Klaus Schmidinger 2002-04-19 12:40:04 +02:00
parent 849ec98c3d
commit 8ec5c0d926
3 changed files with 40 additions and 32 deletions
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2
CONTRIBUTORS
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@ -157,6 +157,8 @@ Werner Fink <werner@suse.de>
for helping to debug leftover 'zombie' processes when closing a pipe for helping to debug leftover 'zombie' processes when closing a pipe
for making the Dolby Digital thread start only if the recording actually for making the Dolby Digital thread start only if the recording actually
contains Dolby Digital data contains Dolby Digital data
for improving thread locking in the ring buffer to avoid possible race conditions
under heavy load
Rolf Hakenes <hakenes@hippomi.de> Rolf Hakenes <hakenes@hippomi.de>
for providing 'libdtv' and adapting the EIT mechanisms to it for providing 'libdtv' and adapting the EIT mechanisms to it

4
HISTORY
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@ -1191,7 +1191,7 @@ Video Disk Recorder Revision History
same name was manually deleted on a system with more than one video directory same name was manually deleted on a system with more than one video directory
(thanks to Dirk Wiebel for reporting this one). (thanks to Dirk Wiebel for reporting this one).
2002-04-13: Version 1.0.1 2002-04-19: Version 1.0.1
- Added some DVB-T channels for Berlin (Germany) to channels.conf.terr (thanks to - Added some DVB-T channels for Berlin (Germany) to channels.conf.terr (thanks to
Andreas Roedl). Andreas Roedl).
@ -1204,3 +1204,5 @@ Video Disk Recorder Revision History
any timers referencing a channel with a number higher than 102 should be any timers referencing a channel with a number higher than 102 should be
checked and adapted if necessary (this only applies if you are using the default checked and adapted if necessary (this only applies if you are using the default
'channels.conf'). 'channels.conf').
- Improved thread locking in the ring buffer to avoid possible race conditions
under heavy load (thanks to Werner Fink).

66
ringbuffer.c
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@ -7,7 +7,7 @@
* Parts of this file were inspired by the 'ringbuffy.c' from the * Parts of this file were inspired by the 'ringbuffy.c' from the
* LinuxDVB driver (see linuxtv.org). * LinuxDVB driver (see linuxtv.org).
* *
* $Id: ringbuffer.c 1.5 2001/11/03 09:50:46 kls Exp $ * $Id: ringbuffer.c 1.6 2002/04/19 12:38:44 kls Exp $
*/ */
#include "ringbuffer.h" #include "ringbuffer.h"
@ -154,7 +154,6 @@ int cRingBufferLinear::Put(const uchar *Data, int Count)
Lock(); Lock();
int rest = Size() - head; int rest = Size() - head;
int diff = tail - head; int diff = tail - head;
Unlock();
int free = (diff > 0) ? diff - 1 : Size() + diff - 1; int free = (diff > 0) ? diff - 1 : Size() + diff - 1;
if (statistics) { if (statistics) {
int fill = Size() - free - 1 + Count; int fill = Size() - free - 1 + Count;
@ -167,22 +166,25 @@ int cRingBufferLinear::Put(const uchar *Data, int Count)
dsyslog(LOG_INFO, "buffer usage: %d%%", percent); dsyslog(LOG_INFO, "buffer usage: %d%%", percent);
} }
} }
if (free <= 0) if (free > 0) {
return 0; if (free < Count)
if (free < Count) Count = free;
Count = free; if (Count > maxFill)
if (Count > maxFill) maxFill = Count;
maxFill = Count; if (Count >= rest) {
if (Count >= rest) { memcpy(buffer + head, Data, rest);
memcpy(buffer + head, Data, rest); if (Count - rest)
if (Count - rest) memcpy(buffer, Data + rest, Count - rest);
memcpy(buffer, Data + rest, Count - rest); head = Count - rest;
head = Count - rest; }
} else {
else { memcpy(buffer + head, Data, Count);
memcpy(buffer + head, Data, Count); head += Count;
head += Count; }
} }
else
Count = 0;
Unlock();
} }
return Count; return Count;
} }
@ -193,22 +195,24 @@ int cRingBufferLinear::Get(uchar *Data, int Count)
Lock(); Lock();
int rest = Size() - tail; int rest = Size() - tail;
int diff = head - tail; int diff = head - tail;
Unlock();
int cont = (diff >= 0) ? diff : Size() + diff; int cont = (diff >= 0) ? diff : Size() + diff;
if (rest <= 0) if (rest > 0) {
return 0; if (cont < Count)
if (cont < Count) Count = cont;
Count = cont; if (Count >= rest) {
if (Count >= rest) { memcpy(Data, buffer + tail, rest);
memcpy(Data, buffer + tail, rest); if (Count - rest)
if (Count - rest) memcpy(Data + rest, buffer, Count - rest);
memcpy(Data + rest, buffer, Count - rest); tail = Count - rest;
tail = Count - rest; }
} else {
else { memcpy(Data, buffer + tail, Count);
memcpy(Data, buffer + tail, Count); tail += Count;
tail += Count; }
} }
else
Count = 0;
Unlock();
} }
return Count; return Count;
} }