lldb/source/Utility/Broadcaster.cpp

   1 //===-- Broadcaster.cpp ---------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "lldb/Utility/Broadcaster.h"
  10 #include "lldb/Utility/Event.h"
  11 #include "lldb/Utility/LLDBLog.h"
  12 #include "lldb/Utility/Listener.h"
  13 #include "lldb/Utility/Stream.h"
  14 #include "lldb/Utility/StreamString.h"
  15
  16 #include <algorithm>
  17 #include <memory>
  18 #include <utility>
  19
  20 #include <cassert>
  21 #include <cstddef>
  22
  23 using namespace lldb;
  24 using namespace lldb_private;
  25
  26 Broadcaster::Broadcaster(BroadcasterManagerSP manager_sp, std::string name)
  27     : m_broadcaster_sp(std::make_shared<BroadcasterImpl>(*this)),
  28       m_manager_sp(std::move(manager_sp)), m_broadcaster_name(std::move(name)) {
  29   Log *log = GetLog(LLDBLog::Object);
  30   LLDB_LOG(log, "{0} Broadcaster::Broadcaster(\"{1}\")",
  31            static_cast<void *>(this), GetBroadcasterName());
  32 }
  33
  34 Broadcaster::BroadcasterImpl::BroadcasterImpl(Broadcaster &broadcaster)
  35     : m_broadcaster(broadcaster), m_listeners(), m_listeners_mutex(),
  36       m_hijacking_listeners(), m_hijacking_masks() {}
  37
  38 Broadcaster::~Broadcaster() {
  39   Log *log = GetLog(LLDBLog::Object);
  40   LLDB_LOG(log, "{0} Broadcaster::~Broadcaster(\"{1}\")",
  41            static_cast<void *>(this), GetBroadcasterName());
  42
  43   Clear();
  44 }
  45
  46 void Broadcaster::CheckInWithManager() {
  47   if (m_manager_sp) {
  48     m_manager_sp->SignUpListenersForBroadcaster(*this);
  49   }
  50 }
  51
  52 llvm::SmallVector<std::pair<ListenerSP, uint32_t &>, 4>
  53 Broadcaster::BroadcasterImpl::GetListeners(uint32_t event_mask,
  54                                            bool include_primary) {
  55   llvm::SmallVector<std::pair<ListenerSP, uint32_t &>, 4> listeners;
  56   size_t max_count = m_listeners.size();
  57   if (include_primary)
  58     max_count++;
  59   listeners.reserve(max_count);
  60
  61   for (auto it = m_listeners.begin(); it != m_listeners.end();) {
  62     lldb::ListenerSP curr_listener_sp(it->first.lock());
  63     if (curr_listener_sp) {
  64       if (it->second & event_mask)
  65         listeners.emplace_back(std::move(curr_listener_sp), it->second);
  66       ++it;
  67     } else
  68       // If our listener_wp didn't resolve, then we should remove this entry.
  69       it = m_listeners.erase(it);
  70   }
  71   if (include_primary && m_primary_listener_sp)
  72     listeners.emplace_back(m_primary_listener_sp, m_primary_listener_mask);
  73
  74   return listeners;
  75 }
  76
  77 bool Broadcaster::BroadcasterImpl::HasListeners(uint32_t event_mask) {
  78   if (m_primary_listener_sp)
  79     return true;
  80   for (auto it = m_listeners.begin(); it != m_listeners.end(); it++) {
  81     // Don't return a listener if the other end of the WP is gone:
  82     lldb::ListenerSP curr_listener_sp(it->first.lock());
  83     if (curr_listener_sp && (it->second & event_mask))
  84       return true;
  85   }
  86   return false;
  87 }
  88
  89 void Broadcaster::BroadcasterImpl::Clear() {
  90   std::lock_guard<std::mutex> guard(m_listeners_mutex);
  91
  92   // Make sure the listener forgets about this broadcaster. We do this in the
  93   // broadcaster in case the broadcaster object initiates the removal.
  94   for (auto &pair : GetListeners())
  95     pair.first->BroadcasterWillDestruct(&m_broadcaster);
  96
  97   m_listeners.clear();
  98   m_primary_listener_sp.reset();
  99 }
 100
 101 Broadcaster *Broadcaster::BroadcasterImpl::GetBroadcaster() {
 102   return &m_broadcaster;
 103 }
 104
 105 bool Broadcaster::BroadcasterImpl::GetEventNames(
 106     Stream &s, uint32_t event_mask, bool prefix_with_broadcaster_name) const {
 107   uint32_t num_names_added = 0;
 108   if (event_mask && !m_event_names.empty()) {
 109     event_names_map::const_iterator end = m_event_names.end();
 110     for (uint32_t bit = 1u, mask = event_mask; mask != 0 && bit != 0;
 111          bit <<= 1, mask >>= 1) {
 112       if (mask & 1) {
 113         event_names_map::const_iterator pos = m_event_names.find(bit);
 114         if (pos != end) {
 115           if (num_names_added > 0)
 116             s.PutCString(", ");
 117
 118           if (prefix_with_broadcaster_name) {
 119             s.PutCString(GetBroadcasterName());
 120             s.PutChar('.');
 121           }
 122           s.PutCString(pos->second);
 123           ++num_names_added;
 124         }
 125       }
 126     }
 127   }
 128   return num_names_added > 0;
 129 }
 130
 131 void Broadcaster::AddInitialEventsToListener(
 132     const lldb::ListenerSP &listener_sp, uint32_t requested_events) {}
 133
 134 uint32_t
 135 Broadcaster::BroadcasterImpl::AddListener(const lldb::ListenerSP &listener_sp,
 136                                           uint32_t event_mask) {
 137   if (!listener_sp)
 138     return 0;
 139
 140   std::lock_guard<std::mutex> guard(m_listeners_mutex);
 141
 142   // See if we already have this listener, and if so, update its mask
 143
 144   bool handled = false;
 145
 146   if (listener_sp == m_primary_listener_sp)
 147     // This already handles all bits so just return the mask:
 148     return event_mask;
 149
 150   for (auto &pair : GetListeners(UINT32_MAX, false)) {
 151     if (pair.first == listener_sp) {
 152       handled = true;
 153       pair.second |= event_mask;
 154       m_broadcaster.AddInitialEventsToListener(listener_sp, event_mask);
 155       break;
 156     }
 157   }
 158
 159   if (!handled) {
 160     // Grant a new listener the available event bits
 161     m_listeners.push_back(
 162         std::make_pair(lldb::ListenerWP(listener_sp), event_mask));
 163
 164     // Individual broadcasters decide whether they have outstanding data when a
 165     // listener attaches, and insert it into the listener with this method.
 166     m_broadcaster.AddInitialEventsToListener(listener_sp, event_mask);
 167   }
 168
 169   // Return the event bits that were granted to the listener
 170   return event_mask;
 171 }
 172
 173 bool Broadcaster::BroadcasterImpl::EventTypeHasListeners(uint32_t event_type) {
 174   std::lock_guard<std::mutex> guard(m_listeners_mutex);
 175
 176   if (!m_hijacking_listeners.empty() && event_type & m_hijacking_masks.back())
 177     return true;
 178
 179   // The primary listener listens for all event bits:
 180   if (m_primary_listener_sp)
 181     return true;
 182
 183   return HasListeners(event_type);
 184 }
 185
 186 bool Broadcaster::BroadcasterImpl::RemoveListener(
 187     lldb_private::Listener *listener, uint32_t event_mask) {
 188   if (!listener)
 189     return false;
 190
 191   if (listener == m_primary_listener_sp.get()) {
 192     // Primary listeners listen for all the event bits for their broadcaster,
 193     // so remove this altogether if asked:
 194     m_primary_listener_sp.reset();
 195     return true;
 196   }
 197
 198   std::lock_guard<std::mutex> guard(m_listeners_mutex);
 199   for (auto it = m_listeners.begin(); it != m_listeners.end();) {
 200     lldb::ListenerSP curr_listener_sp(it->first.lock());
 201
 202     if (!curr_listener_sp) {
 203       // The weak pointer for this listener didn't resolve, lets' prune it
 204       // as we go.
 205       it = m_listeners.erase(it);
 206       continue;
 207     }
 208
 209     if (curr_listener_sp.get() == listener) {
 210       it->second &= ~event_mask;
 211       // If we removed all the event bits from a listener, remove it from
 212       // the list as well.
 213       if (!it->second)
 214         m_listeners.erase(it);
 215       return true;
 216     }
 217     it++;
 218   }
 219   return false;
 220 }
 221
 222 bool Broadcaster::BroadcasterImpl::RemoveListener(
 223     const lldb::ListenerSP &listener_sp, uint32_t event_mask) {
 224   return RemoveListener(listener_sp.get(), event_mask);
 225 }
 226
 227 void Broadcaster::BroadcasterImpl::BroadcastEvent(EventSP &event_sp) {
 228   return PrivateBroadcastEvent(event_sp, false);
 229 }
 230
 231 void Broadcaster::BroadcasterImpl::BroadcastEventIfUnique(EventSP &event_sp) {
 232   return PrivateBroadcastEvent(event_sp, true);
 233 }
 234
 235 void Broadcaster::BroadcasterImpl::PrivateBroadcastEvent(EventSP &event_sp,
 236                                                          bool unique) {
 237   // Can't add a nullptr event...
 238   if (!event_sp)
 239     return;
 240
 241   // Update the broadcaster on this event
 242   event_sp->SetBroadcaster(&m_broadcaster);
 243
 244   const uint32_t event_type = event_sp->GetType();
 245
 246   std::lock_guard<std::mutex> guard(m_listeners_mutex);
 247
 248   ListenerSP hijacking_listener_sp;
 249
 250   if (!m_hijacking_listeners.empty()) {
 251     assert(!m_hijacking_masks.empty());
 252     hijacking_listener_sp = m_hijacking_listeners.back();
 253     if ((event_type & m_hijacking_masks.back()) == 0)
 254       hijacking_listener_sp.reset();
 255   }
 256
 257   Log *log = GetLog(LLDBLog::Events);
 258   if (!log && event_sp->GetData())
 259     log = event_sp->GetData()->GetLogChannel();
 260
 261   if (log) {
 262     StreamString event_description;
 263     event_sp->Dump(&event_description);
 264     LLDB_LOG(log,
 265              "{0:x} Broadcaster(\"{1}\")::BroadcastEvent (event_sp = {2}, "
 266              "unique={3}) hijack = {4:x}",
 267              static_cast<void *>(this), GetBroadcasterName(),
 268              event_description.GetData(), unique,
 269              static_cast<void *>(hijacking_listener_sp.get()));
 270   }
 271   ListenerSP primary_listener_sp
 272       = hijacking_listener_sp ? hijacking_listener_sp : m_primary_listener_sp;
 273
 274   if (primary_listener_sp) {
 275     if (unique && primary_listener_sp->PeekAtNextEventForBroadcasterWithType(
 276                       &m_broadcaster, event_type))
 277       return;
 278     // Add the pending listeners but not if the event is hijacked, since that
 279     // is given sole access to the event stream it is hijacking.
 280     // Make sure to do this before adding the event to the primary or it might
 281     // start handling the event before we're done adding all the pending
 282     // listeners.
 283     // Also, don't redo the check for unique here, since otherwise that could
 284     // be racy, and if we send the event to the primary listener then we SHOULD
 285     // send it to the secondary listeners or they will get out of sync with the
 286     // primary listener.
 287     if (!hijacking_listener_sp) {
 288       for (auto &pair : GetListeners(event_type, false))
 289         event_sp->AddPendingListener(pair.first);
 290     }
 291     primary_listener_sp->AddEvent(event_sp);
 292   } else {
 293     for (auto &pair : GetListeners(event_type)) {
 294       if (unique && pair.first->PeekAtNextEventForBroadcasterWithType(
 295                         &m_broadcaster, event_type))
 296         continue;
 297
 298       pair.first->AddEvent(event_sp);
 299     }
 300   }
 301 }
 302
 303 void Broadcaster::BroadcasterImpl::BroadcastEvent(uint32_t event_type) {
 304   auto event_sp = std::make_shared<Event>(event_type, /*data = */ nullptr);
 305   PrivateBroadcastEvent(event_sp, false);
 306 }
 307
 308 void Broadcaster::BroadcasterImpl::BroadcastEvent(
 309     uint32_t event_type, const lldb::EventDataSP &event_data_sp) {
 310   auto event_sp = std::make_shared<Event>(event_type, event_data_sp);
 311   PrivateBroadcastEvent(event_sp, false);
 312 }
 313
 314 void Broadcaster::BroadcasterImpl::BroadcastEventIfUnique(uint32_t event_type) {
 315   auto event_sp = std::make_shared<Event>(event_type, /*data = */ nullptr);
 316   PrivateBroadcastEvent(event_sp, true);
 317 }
 318
 319 void Broadcaster::BroadcasterImpl::SetPrimaryListener(lldb::ListenerSP
 320                                                       listener_sp) {
 321   // This might have already been added as a normal listener, make sure we
 322   // don't hold two copies.
 323   RemoveListener(listener_sp.get(), UINT32_MAX);
 324   m_primary_listener_sp = listener_sp;
 325
 326 }
 327
 328 bool Broadcaster::BroadcasterImpl::HijackBroadcaster(
 329     const lldb::ListenerSP &listener_sp, uint32_t event_mask) {
 330   std::lock_guard<std::mutex> guard(m_listeners_mutex);
 331
 332   Log *log = GetLog(LLDBLog::Events);
 333   LLDB_LOG(
 334       log,
 335       "{0} Broadcaster(\"{1}\")::HijackBroadcaster (listener(\"{2}\")={3})",
 336       static_cast<void *>(this), GetBroadcasterName(),
 337       listener_sp->m_name.c_str(), static_cast<void *>(listener_sp.get()));
 338   m_hijacking_listeners.push_back(listener_sp);
 339   m_hijacking_masks.push_back(event_mask);
 340   return true;
 341 }
 342
 343 bool Broadcaster::BroadcasterImpl::IsHijackedForEvent(uint32_t event_mask) {
 344   std::lock_guard<std::mutex> guard(m_listeners_mutex);
 345
 346   if (!m_hijacking_listeners.empty())
 347     return (event_mask & m_hijacking_masks.back()) != 0;
 348   return false;
 349 }
 350
 351 const char *Broadcaster::BroadcasterImpl::GetHijackingListenerName() {
 352   if (m_hijacking_listeners.size()) {
 353     return m_hijacking_listeners.back()->GetName();
 354   }
 355   return nullptr;
 356 }
 357
 358 void Broadcaster::BroadcasterImpl::RestoreBroadcaster() {
 359   std::lock_guard<std::mutex> guard(m_listeners_mutex);
 360
 361   if (!m_hijacking_listeners.empty()) {
 362     ListenerSP listener_sp = m_hijacking_listeners.back();
 363     Log *log = GetLog(LLDBLog::Events);
 364     LLDB_LOG(log,
 365              "{0} Broadcaster(\"{1}\")::RestoreBroadcaster (about to pop "
 366              "listener(\"{2}\")={3})",
 367              static_cast<void *>(this), GetBroadcasterName(),
 368              listener_sp->m_name.c_str(),
 369              static_cast<void *>(listener_sp.get()));
 370     m_hijacking_listeners.pop_back();
 371   }
 372   if (!m_hijacking_masks.empty())
 373     m_hijacking_masks.pop_back();
 374 }
 375
 376 llvm::StringRef Broadcaster::GetBroadcasterClass() const {
 377   static constexpr llvm::StringLiteral class_name("lldb.anonymous");
 378   return class_name;
 379 }
 380
 381 bool BroadcastEventSpec::operator<(const BroadcastEventSpec &rhs) const {
 382   if (GetBroadcasterClass() == rhs.GetBroadcasterClass()) {
 383     return GetEventBits() < rhs.GetEventBits();
 384   }
 385   return GetBroadcasterClass() < rhs.GetBroadcasterClass();
 386 }
 387
 388 BroadcasterManager::BroadcasterManager() : m_manager_mutex() {}
 389
 390 lldb::BroadcasterManagerSP BroadcasterManager::MakeBroadcasterManager() {
 391   return lldb::BroadcasterManagerSP(new BroadcasterManager());
 392 }
 393
 394 uint32_t BroadcasterManager::RegisterListenerForEventsNoLock(
 395     const lldb::ListenerSP &listener_sp, const BroadcastEventSpec &event_spec) {
 396   collection::iterator iter = m_event_map.begin(), end_iter = m_event_map.end();
 397   uint32_t available_bits = event_spec.GetEventBits();
 398
 399   auto class_matches = [&event_spec](const event_listener_key &input) -> bool {
 400     return input.first.GetBroadcasterClass() ==
 401            event_spec.GetBroadcasterClass();
 402   };
 403
 404   while (iter != end_iter &&
 405          (iter = find_if(iter, end_iter, class_matches)) != end_iter) {
 406     available_bits &= ~((*iter).first.GetEventBits());
 407     iter++;
 408   }
 409
 410   if (available_bits != 0) {
 411     m_event_map.insert(event_listener_key(
 412         BroadcastEventSpec(event_spec.GetBroadcasterClass(), available_bits),
 413         listener_sp));
 414     m_listeners.insert(listener_sp);
 415   }
 416
 417   return available_bits;
 418 }
 419
 420 bool BroadcasterManager::UnregisterListenerForEventsNoLock(
 421     const lldb::ListenerSP &listener_sp, const BroadcastEventSpec &event_spec) {
 422   bool removed_some = false;
 423
 424   if (m_listeners.erase(listener_sp) == 0)
 425     return false;
 426
 427   auto listener_matches_and_shared_bits =
 428       [&listener_sp, &event_spec](const event_listener_key &input) -> bool {
 429     return input.first.GetBroadcasterClass() ==
 430                event_spec.GetBroadcasterClass() &&
 431            (input.first.GetEventBits() & event_spec.GetEventBits()) != 0 &&
 432            input.second == listener_sp;
 433   };
 434   std::vector<BroadcastEventSpec> to_be_readded;
 435   uint32_t event_bits_to_remove = event_spec.GetEventBits();
 436
 437   // Go through the map and delete the exact matches, and build a list of
 438   // matches that weren't exact to re-add:
 439   for (auto iter = m_event_map.begin(), end = m_event_map.end();;) {
 440     iter = find_if(iter, end, listener_matches_and_shared_bits);
 441     if (iter == end)
 442       break;
 443     uint32_t iter_event_bits = (*iter).first.GetEventBits();
 444     removed_some = true;
 445
 446     if (event_bits_to_remove != iter_event_bits) {
 447       uint32_t new_event_bits = iter_event_bits & ~event_bits_to_remove;
 448       to_be_readded.emplace_back(event_spec.GetBroadcasterClass(),
 449                                  new_event_bits);
 450     }
 451     iter = m_event_map.erase(iter);
 452   }
 453
 454   // Okay now add back the bits that weren't completely removed:
 455   for (const auto &event : to_be_readded) {
 456     m_event_map.insert(event_listener_key(event, listener_sp));
 457   }
 458
 459   return removed_some;
 460 }
 461
 462 ListenerSP BroadcasterManager::GetListenerForEventSpec(
 463     const BroadcastEventSpec &event_spec) const {
 464   std::lock_guard<std::mutex> guard(m_manager_mutex);
 465
 466   auto event_spec_matches =
 467       [&event_spec](const event_listener_key &input) -> bool {
 468     return input.first.IsContainedIn(event_spec);
 469   };
 470
 471   auto iter = llvm::find_if(m_event_map, event_spec_matches);
 472   if (iter != m_event_map.end())
 473     return (*iter).second;
 474
 475   return nullptr;
 476 }
 477
 478 void BroadcasterManager::RemoveListener(Listener *listener) {
 479   std::lock_guard<std::mutex> guard(m_manager_mutex);
 480   auto listeners_predicate =
 481       [&listener](const lldb::ListenerSP &input) -> bool {
 482     return input.get() == listener;
 483   };
 484
 485   if (auto iter = llvm::find_if(m_listeners, listeners_predicate);
 486       iter != m_listeners.end())
 487     m_listeners.erase(iter);
 488
 489   auto events_predicate = [listener](const event_listener_key &input) -> bool {
 490     return input.second.get() == listener;
 491   };
 492
 493   // TODO: use 'std::map::erase_if' when moving to c++20.
 494   for (auto iter = m_event_map.begin(), end = m_event_map.end();;) {
 495     iter = find_if(iter, end, events_predicate);
 496     if (iter == end)
 497       break;
 498
 499     iter = m_event_map.erase(iter);
 500   }
 501 }
 502
 503 void BroadcasterManager::RemoveListener(const lldb::ListenerSP &listener_sp) {
 504   std::lock_guard<std::mutex> guard(m_manager_mutex);
 505
 506   auto listener_matches =
 507       [&listener_sp](const event_listener_key &input) -> bool {
 508     return input.second == listener_sp;
 509   };
 510
 511   if (m_listeners.erase(listener_sp) == 0)
 512     return;
 513
 514   // TODO: use 'std::map::erase_if' when moving to c++20.
 515   for (auto iter = m_event_map.begin(), end_iter = m_event_map.end();;) {
 516     iter = find_if(iter, end_iter, listener_matches);
 517     if (iter == end_iter)
 518       break;
 519
 520     iter = m_event_map.erase(iter);
 521   }
 522 }
 523
 524 void BroadcasterManager::SignUpListenersForBroadcaster(
 525     Broadcaster &broadcaster) {
 526   std::lock_guard<std::mutex> guard(m_manager_mutex);
 527
 528   collection::iterator iter = m_event_map.begin(), end_iter = m_event_map.end();
 529
 530   auto class_matches = [&broadcaster](const event_listener_key &input) -> bool {
 531     return input.first.GetBroadcasterClass() ==
 532            broadcaster.GetBroadcasterClass();
 533   };
 534
 535   while (iter != end_iter &&
 536          (iter = find_if(iter, end_iter, class_matches)) != end_iter) {
 537     (*iter).second->StartListeningForEvents(&broadcaster,
 538                                             (*iter).first.GetEventBits());
 539     iter++;
 540   }
 541 }
 542
 543 void BroadcasterManager::Clear() {
 544   std::lock_guard<std::mutex> guard(m_manager_mutex);
 545
 546   for (auto &listener : m_listeners)
 547     listener->BroadcasterManagerWillDestruct(this->shared_from_this());
 548   m_listeners.clear();
 549   m_event_map.clear();
 550 }