src/ThreadScheduler.cpp

   1 //
   2 // This file is part of the aMule Project.
   3 //
   4 // Copyright (c) 2006-2008 Mikkel Schubert ( xaignar@amule.org / http://www.amule.org )
   5 //
   6 // Any parts of this program derived from the xMule, lMule or eMule project,
   7 // or contributed by third-party developers are copyrighted by their
   8 // respective authors.
   9 //
  10 // This program is free software; you can redistribute it and/or modify
  11 // it under the terms of the GNU General Public License as published by
  12 // the Free Software Foundation; either version 2 of the License, or
  13 // (at your option) any later version.
  14 //
  15 // This program is distributed in the hope that it will be useful,
  16 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 // GNU General Public License for more details.
  19 //
  20 // You should have received a copy of the GNU General Public License
  21 // along with this program; if not, write to the Free Software
  22 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
  23 //
  24
  25 #include "ThreadScheduler.h"    // Interface declarations
  26 #include "Logger.h"                             // Needed for Add(Debug)LogLineM
  27 #include <common/Format.h>              // Needed for CFormat
  28 #include "ScopedPtr.h"                  // Needed for CScopedPtr
  29
  30 #include <algorithm>                    // Needed for std::sort         // Do_not_auto_remove (mingw-gcc-3.4.5)
  31
  32 //! Global lock the scheduler and its thread.
  33 static wxMutex s_lock;
  34 //! Pointer to the global scheduler instance (automatically instantiated).
  35 static CThreadScheduler* s_scheduler = NULL;
  36 //! Specifies if the scheduler is running.
  37 static bool     s_running = false;
  38 //! Specifies if the gobal scheduler has been terminated.
  39 static bool s_terminated = false;
  40
  41 /**
  42  * This class is used in a custom implementation of wxThreadHelper.
  43  *
  44  * The reason for not using wxThreadHelper are as follows:
  45  *  - wxThreadHelper makes use of wxThread:Kill, which is warned against
  46  *    serveral times in the docs, and even calls it in its destructor.
  47  *  - Managing the thread-object is difficult, since the only way to
  48  *    destroy it is to create a new thread.
  49  */
  50 class CTaskThread : public CMuleThread
  51 {
  52 public:
  53         CTaskThread(CThreadScheduler* owner)
  54                 : CMuleThread(wxTHREAD_JOINABLE),
  55                   m_owner(owner)
  56         {
  57         }
  58
  59         //! For simplicity's sake, all code is placed in CThreadScheduler::Entry
  60         void* Entry() {
  61                 return m_owner->Entry();
  62         }
  63
  64 private:
  65         //! The scheduler owning this thread.
  66         CThreadScheduler* m_owner;
  67 };
  68
  69
  70 void CThreadScheduler::Start()
  71 {
  72         wxMutexLocker lock(s_lock);
  73
  74         s_running = true;
  75         s_terminated = false;
  76
  77         // Ensures that a thread is started if tasks are already waiting.
  78         if (s_scheduler) {
  79                 AddDebugLogLineM(false, logThreads, wxT("Starting scheduler"));
  80                 s_scheduler->CreateSchedulerThread();
  81         }
  82 }
  83
  84
  85 void CThreadScheduler::Terminate()
  86 {
  87         AddDebugLogLineM(false, logThreads, wxT("Terminating scheduler"));
  88         CThreadScheduler* ptr = NULL;
  89
  90         {
  91                 wxMutexLocker lock(s_lock);
  92
  93                 // Safely unlink the scheduler, as to avoid race-conditions.
  94                 ptr = s_scheduler;
  95                 s_running = false;
  96                 s_terminated = true;
  97                 s_scheduler = NULL;
  98         }
  99
 100         delete ptr;
 101         AddDebugLogLineM(false, logThreads, wxT("Scheduler terminated"));
 102 }
 103
 104
 105 bool CThreadScheduler::AddTask(CThreadTask* task, bool overwrite)
 106 {
 107         wxMutexLocker lock(s_lock);
 108
 109         // When terminated (on shutdown), all tasks are ignored.
 110         if (s_terminated) {
 111                 AddDebugLogLineM(false, logThreads, wxT("Task discared: ") + task->GetDesc());
 112                 delete task;
 113                 return false;
 114         } else if (s_scheduler == NULL) {
 115                 s_scheduler = new CThreadScheduler();
 116                 AddDebugLogLineM(false, logThreads, wxT("Scheduler created."));
 117         }
 118
 119         return s_scheduler->DoAddTask(task, overwrite);
 120 }
 121
 122
 123 /** Returns string representation of error code. */
 124 wxString GetErrMsg(wxThreadError err)
 125 {
 126         switch (err) {
 127                 case wxTHREAD_NO_ERROR:         return wxT("wxTHREAD_NO_ERROR");
 128                 case wxTHREAD_NO_RESOURCE:      return wxT("wxTHREAD_NO_RESOURCE");
 129                 case wxTHREAD_RUNNING:          return wxT("wxTHREAD_RUNNING");
 130                 case wxTHREAD_NOT_RUNNING:      return wxT("wxTHREAD_NOT_RUNNING");
 131                 case wxTHREAD_KILLED:           return wxT("wxTHREAD_KILLED");
 132                 case wxTHREAD_MISC_ERROR:       return wxT("wxTHREAD_MISC_ERROR");
 133                 default:
 134                         return wxT("Unknown error");
 135         }
 136 }
 137
 138
 139 void CThreadScheduler::CreateSchedulerThread()
 140 {
 141         if ((m_thread && m_thread->IsAlive()) || m_tasks.empty()) {
 142                 return;
 143         }
 144
 145         // A thread can only be run once, so the old one must be safely disposed of
 146         if (m_thread) {
 147                 AddDebugLogLineM(false, logThreads, wxT("CreateSchedulerThread: Disposing of old thread."));
 148                 m_thread->Stop();
 149                 delete m_thread;
 150         }
 151
 152         m_thread = new CTaskThread(this);
 153
 154         wxThreadError err = m_thread->Create();
 155         if (err == wxTHREAD_NO_ERROR) {
 156                 // Try to avoid reducing the latency of the main thread
 157                 m_thread->SetPriority(WXTHREAD_MIN_PRIORITY);
 158
 159                 err = m_thread->Run();
 160                 if (err == wxTHREAD_NO_ERROR) {
 161                         AddDebugLogLineM(false, logThreads, wxT("Scheduler thread started"));
 162                         return;
 163                 } else {
 164                         AddDebugLogLineM(true, logThreads, wxT("Error while starting scheduler thread: ") + GetErrMsg(err));
 165                 }
 166         } else {
 167                 AddDebugLogLineM(true, logThreads, wxT("Error while creating scheduler thread: ") + GetErrMsg(err));
 168         }
 169
 170         // Creation or running failed.
 171         m_thread->Stop();
 172         delete m_thread;
 173         m_thread = NULL;
 174 }
 175
 176
 177 /** This is the sorter functor for the task-queue. */
 178 struct CTaskSorter
 179 {
 180         bool operator()(const CThreadScheduler::CEntryPair& a, const CThreadScheduler::CEntryPair& b) {
 181                 if (a.first->GetPriority() != b.first->GetPriority()) {
 182                         return a.first->GetPriority() > b.first->GetPriority();
 183                 }
 184
 185                 // Compare tasks numbers.
 186                 return a.second < b.second;
 187         }
 188 };
 189
 190
 191
 192 CThreadScheduler::CThreadScheduler()
 193         : m_tasksDirty(false),
 194           m_thread(NULL),
 195           m_currentTask(NULL)
 196 {
 197
 198 }
 199
 200
 201 CThreadScheduler::~CThreadScheduler()
 202 {
 203         if (m_thread) {
 204                 m_thread->Stop();
 205                 delete m_thread;
 206         }
 207 }
 208
 209
 210 size_t CThreadScheduler::GetTaskCount() const
 211 {
 212         wxMutexLocker lock(s_lock);
 213
 214         return m_tasks.size();
 215 }
 216
 217
 218 bool CThreadScheduler::DoAddTask(CThreadTask* task, bool overwrite)
 219 {
 220         // GetTick is too lowres, so we just use a counter to ensure that
 221         // the sorted order will match the order in which the tasks were added.
 222         static unsigned taskAge = 0;
 223
 224         // Get the map for this task type, implicitly creating it as needed.
 225         CDescMap& map = m_taskDescs[task->GetType()];
 226
 227         CDescMap::value_type entry(task->GetDesc(), task);
 228         if (map.insert(entry).second) {
 229                 AddDebugLogLineM(false, logThreads, wxT("Task scheduled: ") + task->GetType() + wxT(" - ") + task->GetDesc());
 230                 m_tasks.push_back(CEntryPair(task, taskAge++));
 231                 m_tasksDirty = true;
 232         } else if (overwrite) {
 233                 AddDebugLogLineM(false, logThreads, wxT("Task overwritten: ") + task->GetType() + wxT(" - ") + task->GetDesc());
 234
 235                 CThreadTask* existingTask = map[task->GetDesc()];
 236                 if (m_currentTask == existingTask) {
 237                         // The duplicate is already being executed, abort it.
 238                         m_currentTask->m_abort = true;
 239                 } else {
 240                         // Task not yet started, simply remove and delete.
 241                         wxCHECK2(map.erase(existingTask->GetDesc()), /* Do nothing. */);
 242                         delete existingTask;
 243                 }
 244
 245                 m_tasks.push_back(CEntryPair(task, taskAge++));
 246                 map[task->GetDesc()] = task;
 247                 m_tasksDirty = true;
 248         } else {
 249                 AddDebugLogLineM(false, logThreads, wxT("Duplicate task, discarding: ") + task->GetType() + wxT(" - ") + task->GetDesc());
 250                 delete task;
 251                 return false;
 252         }
 253
 254         if (s_running) {
 255                 CreateSchedulerThread();
 256         }
 257
 258         return true;
 259 }
 260
 261
 262 void* CThreadScheduler::Entry()
 263 {
 264         AddDebugLogLineM(false, logThreads, wxT("Entering scheduling loop"));
 265
 266         while (!m_thread->TestDestroy()) {
 267                 CScopedPtr<CThreadTask> task(NULL);
 268
 269                 {
 270                         wxMutexLocker lock(s_lock);
 271
 272                         // Resort tasks by priority/age if list has been modified.
 273                         if (m_tasksDirty) {
 274                                 AddDebugLogLineM(false, logThreads, wxT("Resorting tasks"));
 275                                 std::sort(m_tasks.begin(), m_tasks.end(), CTaskSorter());
 276                                 m_tasksDirty = false;
 277                         } else if (m_tasks.empty()) {
 278                                 AddDebugLogLineM(false, logThreads, wxT("No more tasks, stopping"));
 279                                 break;
 280                         }
 281
 282                         // Select the next task
 283                         task.reset(m_tasks.front().first);
 284                         m_tasks.pop_front();
 285                         m_currentTask = task.get();
 286                 }
 287
 288                 AddDebugLogLineM(false, logThreads, wxT("Current task: ") + task->GetType() + wxT(" - ") + task->GetDesc());
 289                 // Execute the task
 290                 task->m_owner = m_thread;
 291                 task->Entry();
 292                 task->OnExit();
 293
 294                 // Check if this was the last task of this type
 295                 bool isLastTask = false;
 296
 297                 {
 298                         wxMutexLocker lock(s_lock);
 299
 300                         // If the task has been aborted, the entry now refers to
 301                         // a different task, so dont remove it. That also means
 302                         // that it cant be the last task of this type.
 303                         if (!task->m_abort) {
 304                                 AddDebugLogLineM(false, logThreads,
 305                                         CFormat(wxT("Completed task '%s%s', %u tasks remaining."))
 306                                                 % task->GetType()
 307                                                 % (task->GetDesc().IsEmpty() ? wxString() : (wxT(" - ") + task->GetDesc()))
 308                                                 % m_tasks.size() );
 309
 310                                 CDescMap& map = m_taskDescs[task->GetType()];
 311                                 if (!map.erase(task->GetDesc())) {
 312                                         wxASSERT(0);
 313                                 } else if (map.empty()) {
 314                                         m_taskDescs.erase(task->GetType());
 315                                         isLastTask = true;
 316                                 }
 317                         }
 318
 319                         m_currentTask = NULL;
 320                 }
 321
 322                 if (isLastTask) {
 323                         // Allow the task to signal that all sub-tasks have been completed
 324                         AddDebugLogLineM(false, logThreads, wxT("Last task, calling OnLastTask"));
 325                         task->OnLastTask();
 326                 }
 327         }
 328
 329         AddDebugLogLineM(false, logThreads, wxT("Leaving scheduling loop"));
 330
 331         return 0;
 332 }
 333
 334
 335
 336 CThreadTask::CThreadTask(const wxString& type, const wxString& desc, ETaskPriority priority)
 337         : m_type(type),
 338           m_desc(desc),
 339           m_priority(priority),
 340           m_owner(NULL),
 341           m_abort(false)
 342 {
 343 }
 344
 345
 346 CThreadTask::~CThreadTask()
 347 {
 348 }
 349
 350
 351 void CThreadTask::OnLastTask()
 352 {
 353         // Does nothing by default.
 354 }
 355
 356
 357 void CThreadTask::OnExit()
 358 {
 359         // Does nothing by default.
 360 }
 361
 362
 363 bool CThreadTask::TestDestroy() const
 364 {
 365         wxCHECK(m_owner, m_abort);
 366
 367         return m_abort || m_owner->TestDestroy();
 368 }
 369
 370
 371 const wxString& CThreadTask::GetType() const
 372 {
 373         return m_type;
 374 }
 375
 376
 377 const wxString& CThreadTask::GetDesc() const
 378 {
 379         return m_desc;
 380 }
 381
 382
 383 ETaskPriority CThreadTask::GetPriority() const
 384 {
 385         return m_priority;
 386 }
 387
 388
 389 // File_checked_for_headers