void CFileCache::Process()
{
if (!m_pCache)
{
CLog::Log(LOGERROR,"CFileCache::Process - sanity failed. no cache strategy");
return;
}
// setup read chunks size
int chunksize = CFile::GetChunkSize(m_source.GetChunkSize(), READ_CACHE_CHUNK_SIZE);
// create our read buffer
auto_aptr<char> buffer(new char[chunksize]);
if (buffer.get() == NULL)
{
CLog::Log(LOGERROR, "%s - failed to allocate read buffer", __FUNCTION__);
return;
}
CWriteRate limiter;
CWriteRate average;
while (!m_bStop)
{
// check for seek events
if (m_seekEvent.WaitMSec(0))
{
m_seekEvent.Reset();
CLog::Log(LOGDEBUG,"%s, request seek on source to %"PRId64, __FUNCTION__, m_seekPos);
m_nSeekResult = m_source.Seek(m_seekPos, SEEK_SET);
if (m_nSeekResult != m_seekPos)
{
CLog::Log(LOGERROR,"%s, error %d seeking. seek returned %"PRId64, __FUNCTION__, (int)GetLastError(), m_nSeekResult);
m_seekPossible = m_source.IoControl(IOCTRL_SEEK_POSSIBLE, NULL);
}
else
{
m_pCache->Reset(m_seekPos);
average.Reset(m_seekPos);
limiter.Reset(m_seekPos);
m_writePos = m_seekPos;
m_readPos = m_seekPos;
m_cacheFull = false;
}
m_seekEnded.Set();
}
while (m_writeRate)
{
if (m_writePos - m_readPos < m_writeRate)
{
limiter.Reset(m_writePos);
break;
}
if (limiter.Rate(m_writePos) < m_writeRate)
break;
if (m_seekEvent.WaitMSec(100))
{
m_seekEvent.Set();
break;
}
}
int iRead = m_source.Read(buffer.get(), chunksize);
if (iRead == 0)
{
CLog::Log(LOGINFO, "CFileCache::Process - Hit eof.");
m_pCache->EndOfInput();
// The thread event will now also cause the wait of an event to return a false.
if (AbortableWait(m_seekEvent) == WAIT_SIGNALED)
{
m_pCache->ClearEndOfInput();
m_seekEvent.Set(); // hack so that later we realize seek is needed
}
else
break;
}
else if (iRead < 0)
m_bStop = true;
int iTotalWrite=0;
while (!m_bStop && (iTotalWrite < iRead))
{
int iWrite = 0;
iWrite = m_pCache->WriteToCache(buffer.get()+iTotalWrite, iRead - iTotalWrite);
// write should always work. all handling of buffering and errors should be
// done inside the cache strategy. only if unrecoverable error happened, WriteToCache would return error and we break.
if (iWrite < 0)
{
CLog::Log(LOGERROR,"CFileCache::Process - error writing to cache");
m_bStop = true;
break;
}
else if (iWrite == 0)
{
m_cacheFull = true;
average.Pause();
m_pCache->m_space.WaitMSec(5);
average.Resume();
}
else
m_cacheFull = false;
iTotalWrite += iWrite;
// check if seek was asked. otherwise if cache is full we'll freeze.
if (m_seekEvent.WaitMSec(0))
{
m_seekEvent.Set(); // make sure we get the seek event later.
break;
}
}
m_writePos += iTotalWrite;
// under estimate write rate by a second, to
// avoid uncertainty at start of caching
m_writeRateActual = average.Rate(m_writePos, 1000);
}
}
void CFileCache::Process()
{
if (!m_pCache)
{
CLog::Log(LOGERROR,"CFileCache::Process - sanity failed. no cache strategy");
return;
}
// create our read buffer
auto_aptr<char> buffer(new char[m_chunkSize]);
if (buffer.get() == NULL)
{
CLog::Log(LOGERROR, "%s - failed to allocate read buffer", __FUNCTION__);
return;
}
CWriteRate limiter;
CWriteRate average;
bool cacheReachEOF = false;
while (!m_bStop)
{
// check for seek events
if (m_seekEvent.WaitMSec(0))
{
m_seekEvent.Reset();
int64_t cacheMaxPos = m_pCache->CachedDataEndPosIfSeekTo(m_seekPos);
cacheReachEOF = (cacheMaxPos == m_source.GetLength());
bool sourceSeekFailed = false;
if (!cacheReachEOF)
{
m_nSeekResult = m_source.Seek(cacheMaxPos, SEEK_SET);
if (m_nSeekResult != cacheMaxPos)
{
CLog::Log(LOGERROR,"CFileCache::Process - Error %d seeking. Seek returned %" PRId64, (int)GetLastError(), m_nSeekResult);
m_seekPossible = m_source.IoControl(IOCTRL_SEEK_POSSIBLE, NULL);
sourceSeekFailed = true;
}
}
if (!sourceSeekFailed)
{
const bool bCompleteReset = m_pCache->Reset(m_seekPos, false);
m_readPos = m_seekPos;
m_writePos = m_pCache->CachedDataEndPos();
assert(m_writePos == cacheMaxPos);
average.Reset(m_writePos, bCompleteReset); // Can only recalculate new average from scratch after a full reset (empty cache)
limiter.Reset(m_writePos);
m_cacheFull = (m_pCache->GetMaxWriteSize(m_chunkSize) == 0);
m_nSeekResult = m_seekPos;
}
m_seekEnded.Set();
}
while (m_writeRate)
{
if (m_writePos - m_readPos < m_writeRate)
{
limiter.Reset(m_writePos);
break;
}
if (limiter.Rate(m_writePos) < m_writeRate)
break;
if (m_seekEvent.WaitMSec(100))
{
m_seekEvent.Set();
break;
}
}
size_t maxWrite = m_pCache->GetMaxWriteSize(m_chunkSize);
m_cacheFull = (maxWrite == 0);
/* Only read from source if there's enough write space in the cache
* else we may keep disposing data and seeking back on (slow) source
*/
if (m_cacheFull && !cacheReachEOF)
{
average.Pause();
m_pCache->m_space.WaitMSec(5);
average.Resume();
continue;
}
ssize_t iRead = 0;
if (!cacheReachEOF)
iRead = m_source.Read(buffer.get(), maxWrite);
if (iRead == 0)
{
CLog::Log(LOGINFO, "CFileCache::Process - Hit eof.");
m_pCache->EndOfInput();
// The thread event will now also cause the wait of an event to return a false.
if (AbortableWait(m_seekEvent) == WAIT_SIGNALED)
{
m_pCache->ClearEndOfInput();
m_seekEvent.Set(); // hack so that later we realize seek is needed
}
else
break;
}
else if (iRead < 0)
m_bStop = true;
int iTotalWrite=0;
while (!m_bStop && (iTotalWrite < iRead))
{
int iWrite = 0;
iWrite = m_pCache->WriteToCache(buffer.get()+iTotalWrite, iRead - iTotalWrite);
// write should always work. all handling of buffering and errors should be
// done inside the cache strategy. only if unrecoverable error happened, WriteToCache would return error and we break.
if (iWrite < 0)
{
CLog::Log(LOGERROR,"CFileCache::Process - error writing to cache");
m_bStop = true;
break;
}
else if (iWrite == 0)
{
average.Pause();
m_pCache->m_space.WaitMSec(5);
average.Resume();
}
iTotalWrite += iWrite;
// check if seek was asked. otherwise if cache is full we'll freeze.
if (m_seekEvent.WaitMSec(0))
{
m_seekEvent.Set(); // make sure we get the seek event later.
break;
}
}
m_writePos += iTotalWrite;
// under estimate write rate by a second, to
// avoid uncertainty at start of caching
m_writeRateActual = average.Rate(m_writePos, 1000);
}
}