在if语句外定义了ed，赋值为m_eventInputManager->getById(ticket)的返回值，如果未找到对应的Event Descriptor,
则返回EventInputManager::EIM_MAYCOME或者EventInputManager::EIM_NEVERTOCOME。
在if语句内也定义了ed, 赋值为m_eventInputManager->getEventDescriptor(mem_page)返回值，这是根据造的空数据的
内存内存地址得到对应的event descriptor，并修改该ED的值为ticket，然后根据ticket将该ed放进对应的List。
但是if语句里有对丢失数据的状态判断，这应该是用到的if外的ed值。在if语句重新定义ed后，覆盖了该if外的ed值，？？？此处是
不是有bug?
178 /**************************************************************/
179 ROS::EventFragment* PCMemoryDataChannel::getFragment(int ticket)
180 /**************************************************************/
181 {
182 evDesc_t *ed;
183 MemoryPage *mem_page;
184 EventFragment *fragment=0;
185
186 DEBUG_TEXT(DFDB_ROSFM, 10, "PCMemoryDataChannel::getFragment: fragment with L1ID " << ticket << " requested");
187 // protect EIM and fast allocate with same mutex
188 m_mutex->lock();
189
190 //Find the requested event
191 ed = m_eventInputManager->getById(ticket);
192
193 if (m_fragType == 0)
194 {
195 DEBUG_TEXT(DFDB_ROSFM, 10, "PCMemoryDataChannel::getFragment: processing ROB fragment");
196 if((intptr_t)ed == EventInputManager::EIM_MAYCOME || (intptr_t)ed == EventInputManager::EIM_NEVERTOCOME)
197 {
198 DEBUG_TEXT(DFDB_ROSFM, 8, "EIM_MAYCOME || EIM_NEVERTOCOME " << ticket << "ed:" << ed <<std::endl);
199 try
200 {
201 fragment = new ROBFragment(m_memoryPool, ticket, m_sourceIdentifier, 0); //create an empty ROB fragment
202 Buffer *mem_buffer = fragment->buffer(); //get the Buffer of the ROB fragment
203 Buffer::page_iterator mem_page_i = mem_buffer->begin();
204 MemoryPage *mem_page = const_cast<MemoryPage *>(*mem_page_i); //get the memory page of the buffer
205 mem_page->lock();
206
207 evDesc_t *ed = m_eventInputManager->getEventDescriptor(mem_page); //get a pointer to the event descriptor
208 ed->L1id = ticket; //set the L1ID
209 m_eventInputManager->createEvent(ed); //Insert the event into the Event Input Manager
210
211 if ((intptr_t)ed == EventInputManager::EIM_MAYCOME)
212 {
213 m_statistics->fragmentsMissed++;
214 fragment->setStatus(EventFragment::STATUS_MAYCOME);
215 DEBUG_TEXT(DFDB_ROSFM, 8, "PCMemoryDataChannel::getFragment: Fragment for L1ID " << ticket << " has not yet arrived");
216 }
217
218 if ((intptr_t)ed == EventInputManager::EIM_NEVERTOCOME)
219 {
220 m_statistics->fragmentsLost++;
221 fragment->setStatus(EventFragment::STATUS_LOST);
222 DEBUG_TEXT(DFDB_ROSFM, 8, "PCMemoryDataChannel::getFragment: Fragment for L1ID " << ticket << " does not exist");
223 CREATE_ROS_EXCEPTION(ex1, CoreException, PCMEMCHAN_LOST, "
L1ID = " << ticket << ", ROL physical addr = " << physicalAddr ess());
224 ers::warning(ex1);
225 }
226 }
227 catch (EventFragmentException& e)
228 {
229 DEBUG_TEXT(DFDB_ROSFM, 8, "PCMemoryDataChannel::getFragment:EventFragmentException");
230 DEBUG_TEXT(DFDB_ROSFM, 5, e);
231 m_mutex->unlock();
232 throw e;
233 }
234 m_mutex->unlock();
235 return(fragment);
236 }
237 }
238
239 if (m_fragType == 1)
240 {
241 DEBUG_TEXT(DFDB_ROSFM, 10, "PCMemoryDataChannel::getFragment: processing full fragment");
242 if ((intptr_t)ed == EventInputManager::EIM_MAYCOME || (intptr_t)ed == EventInputManager::EIM_NEVERTOCOME)
243 {
244 DEBUG_TEXT(DFDB_ROSFM, 5, "PCMemoryDataChannel::getFragment: Fragment for L1ID " << ticket << " is not available");
245 CREATE_ROS_EXCEPTION(ex1, CoreException, NODATA, "L1ID = " << ticket << ", ROL physical addr = " << physicalAddress());
246 throw(ex1);
247 }
248 }
249
250 m_statistics->fragmentsServed++;
251 DEBUG_TEXT(DFDB_ROSFM, 20, "PCMemoryDataChannel::getFragment: getById returns " << HEX(ed));
252 mem_page = ed->myPage;
253
254 DEBUG_TEXT(DFDB_ROSFM, 20, "PCMemoryDataChannel::getFragment: Dumping fields of this event descriptor:");
255 DEBUG_TEXT(DFDB_ROSFM, 20, "PCMemoryDataChannel::getFragment: Address of memory page = " << std::hex << mem_page << std::dec);
256 DEBUG_TEXT(DFDB_ROSFM, 20, "PCMemoryDataChannel::getFragment: Fragment size (bytes) = " << ed->RODFragmentSize);
257 DEBUG_TEXT(DFDB_ROSFM, 20, "PCMemoryDataChannel::getFragment: Fragment status = " << ed->RODFragmentStatus);
258
259 if (m_fragType == 0)
260 {
261 //<+gumh: add time
262 //u_long base = (u_long)(mem_page->address()) ;
263 //u_int *ptr = (u_int *)(base + sizeof(ROBFragment::ROBHeader) + sizeof(RODFragment::RODHeader) + 4 + sizeof(timeval)); // 4 -> status element
264 //struct timeval tv ;
265 //gettimeofday(&tv, NULL) ;
266 //memcpy(ptr, &tv, sizeof(timeval)) ;
267
268 //u_int *ptr = (u_int *)(base + sizeof(ROBFragment::ROBHeader) + sizeof(RODFragment::RODHeader) + 4 + sizeof(timeval)); // 4 -> status element
269 //+>
270
271 //Create a ROB Fragment in the Buffer and initialize it
272 fragment = new ROBFragment(mem_page, ed->RODFragmentSize, 0, m_sourceIdentifier);
273 }
274
275 if (m_fragType == 1)
276 {
277 //Create a Full Fragment in the Buffer
278 fragment = new FullFragment(mem_page);
279 DEBUG_TEXT(DFDB_ROSFM, 20, "PCMemoryDataChannel::getFragment: Full fragment is at " << HEX(fragment));
280 }
281
282 m_mutex->unlock();
283
284 DEBUG_TEXT(DFDB_ROSFM, 10, "PCMemoryDataChannel::getFragment: PCMemoryDataChannel:: got fragment with L1ID " << ticket);
285 DEBUG_TEXT(DFDB_ROSFM, 15, "PCMemoryDataChannel::getFragment: done");
286
287 return(fragment);
288 }