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, const char *name)
27     : m_broadcaster_sp(std::make_shared<BroadcasterImpl>(*this)),
28       m_manager_sp(std::move(manager_sp)), m_broadcaster_name(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() {
54   llvm::SmallVector<std::pair<ListenerSP, uint32_t &>, 4> listeners;
55   listeners.reserve(m_listeners.size());
56 
57   for (auto it = m_listeners.begin(); it != m_listeners.end();) {
58     lldb::ListenerSP curr_listener_sp(it->first.lock());
59     if (curr_listener_sp && it->second) {
60       listeners.emplace_back(std::move(curr_listener_sp), it->second);
61       ++it;
62     } else
63       it = m_listeners.erase(it);
64   }
65 
66   return listeners;
67 }
68 
69 void Broadcaster::BroadcasterImpl::Clear() {
70   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
71 
72   // Make sure the listener forgets about this broadcaster. We do this in the
73   // broadcaster in case the broadcaster object initiates the removal.
74   for (auto &pair : GetListeners())
75     pair.first->BroadcasterWillDestruct(&m_broadcaster);
76 
77   m_listeners.clear();
78 }
79 
80 Broadcaster *Broadcaster::BroadcasterImpl::GetBroadcaster() {
81   return &m_broadcaster;
82 }
83 
84 bool Broadcaster::BroadcasterImpl::GetEventNames(
85     Stream &s, uint32_t event_mask, bool prefix_with_broadcaster_name) const {
86   uint32_t num_names_added = 0;
87   if (event_mask && !m_event_names.empty()) {
88     event_names_map::const_iterator end = m_event_names.end();
89     for (uint32_t bit = 1u, mask = event_mask; mask != 0 && bit != 0;
90          bit <<= 1, mask >>= 1) {
91       if (mask & 1) {
92         event_names_map::const_iterator pos = m_event_names.find(bit);
93         if (pos != end) {
94           if (num_names_added > 0)
95             s.PutCString(", ");
96 
97           if (prefix_with_broadcaster_name) {
98             s.PutCString(GetBroadcasterName());
99             s.PutChar('.');
100           }
101           s.PutCString(pos->second);
102           ++num_names_added;
103         }
104       }
105     }
106   }
107   return num_names_added > 0;
108 }
109 
110 void Broadcaster::AddInitialEventsToListener(
111     const lldb::ListenerSP &listener_sp, uint32_t requested_events) {}
112 
113 uint32_t
114 Broadcaster::BroadcasterImpl::AddListener(const lldb::ListenerSP &listener_sp,
115                                           uint32_t event_mask) {
116   if (!listener_sp)
117     return 0;
118 
119   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
120 
121   // See if we already have this listener, and if so, update its mask
122 
123   bool handled = false;
124 
125   for (auto &pair : GetListeners()) {
126     if (pair.first == listener_sp) {
127       handled = true;
128       pair.second |= event_mask;
129       m_broadcaster.AddInitialEventsToListener(listener_sp, event_mask);
130       break;
131     }
132   }
133 
134   if (!handled) {
135     // Grant a new listener the available event bits
136     m_listeners.push_back(
137         std::make_pair(lldb::ListenerWP(listener_sp), event_mask));
138 
139     // Individual broadcasters decide whether they have outstanding data when a
140     // listener attaches, and insert it into the listener with this method.
141     m_broadcaster.AddInitialEventsToListener(listener_sp, event_mask);
142   }
143 
144   // Return the event bits that were granted to the listener
145   return event_mask;
146 }
147 
148 bool Broadcaster::BroadcasterImpl::EventTypeHasListeners(uint32_t event_type) {
149   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
150 
151   if (!m_hijacking_listeners.empty() && event_type & m_hijacking_masks.back())
152     return true;
153 
154   for (auto &pair : GetListeners()) {
155     if (pair.second & event_type)
156       return true;
157   }
158   return false;
159 }
160 
161 bool Broadcaster::BroadcasterImpl::RemoveListener(
162     lldb_private::Listener *listener, uint32_t event_mask) {
163   if (!listener)
164     return false;
165 
166   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
167   for (auto &pair : GetListeners()) {
168     if (pair.first.get() == listener) {
169       pair.second &= ~event_mask;
170       return true;
171     }
172   }
173   return false;
174 }
175 
176 bool Broadcaster::BroadcasterImpl::RemoveListener(
177     const lldb::ListenerSP &listener_sp, uint32_t event_mask) {
178   return RemoveListener(listener_sp.get(), event_mask);
179 }
180 
181 void Broadcaster::BroadcasterImpl::BroadcastEvent(EventSP &event_sp) {
182   return PrivateBroadcastEvent(event_sp, false);
183 }
184 
185 void Broadcaster::BroadcasterImpl::BroadcastEventIfUnique(EventSP &event_sp) {
186   return PrivateBroadcastEvent(event_sp, true);
187 }
188 
189 void Broadcaster::BroadcasterImpl::PrivateBroadcastEvent(EventSP &event_sp,
190                                                          bool unique) {
191   // Can't add a nullptr event...
192   if (!event_sp)
193     return;
194 
195   // Update the broadcaster on this event
196   event_sp->SetBroadcaster(&m_broadcaster);
197 
198   const uint32_t event_type = event_sp->GetType();
199 
200   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
201 
202   ListenerSP hijacking_listener_sp;
203 
204   if (!m_hijacking_listeners.empty()) {
205     assert(!m_hijacking_masks.empty());
206     hijacking_listener_sp = m_hijacking_listeners.back();
207     if ((event_type & m_hijacking_masks.back()) == 0)
208       hijacking_listener_sp.reset();
209   }
210 
211   if (Log *log = GetLog(LLDBLog::Events)) {
212     StreamString event_description;
213     event_sp->Dump(&event_description);
214     LLDB_LOGF(log,
215               "%p Broadcaster(\"%s\")::BroadcastEvent (event_sp = {%s}, "
216               "unique =%i) hijack = %p",
217               static_cast<void *>(this), GetBroadcasterName(),
218               event_description.GetData(), unique,
219               static_cast<void *>(hijacking_listener_sp.get()));
220   }
221 
222   if (hijacking_listener_sp) {
223     if (unique && hijacking_listener_sp->PeekAtNextEventForBroadcasterWithType(
224                       &m_broadcaster, event_type))
225       return;
226     hijacking_listener_sp->AddEvent(event_sp);
227   } else {
228     for (auto &pair : GetListeners()) {
229       if (!(pair.second & event_type))
230         continue;
231       if (unique && pair.first->PeekAtNextEventForBroadcasterWithType(
232                         &m_broadcaster, event_type))
233         continue;
234 
235       pair.first->AddEvent(event_sp);
236     }
237   }
238 }
239 
240 void Broadcaster::BroadcasterImpl::BroadcastEvent(uint32_t event_type,
241                                                   EventData *event_data) {
242   auto event_sp = std::make_shared<Event>(event_type, event_data);
243   PrivateBroadcastEvent(event_sp, false);
244 }
245 
246 void Broadcaster::BroadcasterImpl::BroadcastEvent(
247     uint32_t event_type, const lldb::EventDataSP &event_data_sp) {
248   auto event_sp = std::make_shared<Event>(event_type, event_data_sp);
249   PrivateBroadcastEvent(event_sp, false);
250 }
251 
252 void Broadcaster::BroadcasterImpl::BroadcastEventIfUnique(
253     uint32_t event_type, EventData *event_data) {
254   auto event_sp = std::make_shared<Event>(event_type, event_data);
255   PrivateBroadcastEvent(event_sp, true);
256 }
257 
258 bool Broadcaster::BroadcasterImpl::HijackBroadcaster(
259     const lldb::ListenerSP &listener_sp, uint32_t event_mask) {
260   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
261 
262   Log *log = GetLog(LLDBLog::Events);
263   LLDB_LOG(
264       log,
265       "{0} Broadcaster(\"{1}\")::HijackBroadcaster (listener(\"{2}\")={3})",
266       static_cast<void *>(this), GetBroadcasterName(),
267       listener_sp->m_name.c_str(), static_cast<void *>(listener_sp.get()));
268   m_hijacking_listeners.push_back(listener_sp);
269   m_hijacking_masks.push_back(event_mask);
270   return true;
271 }
272 
273 bool Broadcaster::BroadcasterImpl::IsHijackedForEvent(uint32_t event_mask) {
274   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
275 
276   if (!m_hijacking_listeners.empty())
277     return (event_mask & m_hijacking_masks.back()) != 0;
278   return false;
279 }
280 
281 const char *Broadcaster::BroadcasterImpl::GetHijackingListenerName() {
282   if (m_hijacking_listeners.size()) {
283     return m_hijacking_listeners.back()->GetName();
284   }
285   return nullptr;
286 }
287 
288 void Broadcaster::BroadcasterImpl::RestoreBroadcaster() {
289   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
290 
291   if (!m_hijacking_listeners.empty()) {
292     ListenerSP listener_sp = m_hijacking_listeners.back();
293     Log *log = GetLog(LLDBLog::Events);
294     LLDB_LOG(log,
295              "{0} Broadcaster(\"{1}\")::RestoreBroadcaster (about to pop "
296              "listener(\"{2}\")={3})",
297              static_cast<void *>(this), GetBroadcasterName(),
298              listener_sp->m_name.c_str(),
299              static_cast<void *>(listener_sp.get()));
300     m_hijacking_listeners.pop_back();
301   }
302   if (!m_hijacking_masks.empty())
303     m_hijacking_masks.pop_back();
304 }
305 
306 ConstString &Broadcaster::GetBroadcasterClass() const {
307   static ConstString class_name("lldb.anonymous");
308   return class_name;
309 }
310 
311 bool BroadcastEventSpec::operator<(const BroadcastEventSpec &rhs) const {
312   if (GetBroadcasterClass() == rhs.GetBroadcasterClass()) {
313     return GetEventBits() < rhs.GetEventBits();
314   }
315   return GetBroadcasterClass() < rhs.GetBroadcasterClass();
316 }
317 
318 BroadcasterManager::BroadcasterManager() : m_manager_mutex() {}
319 
320 lldb::BroadcasterManagerSP BroadcasterManager::MakeBroadcasterManager() {
321   return lldb::BroadcasterManagerSP(new BroadcasterManager());
322 }
323 
324 uint32_t BroadcasterManager::RegisterListenerForEvents(
325     const lldb::ListenerSP &listener_sp, const BroadcastEventSpec &event_spec) {
326   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
327 
328   collection::iterator iter = m_event_map.begin(), end_iter = m_event_map.end();
329   uint32_t available_bits = event_spec.GetEventBits();
330 
331   while (iter != end_iter &&
332          (iter = find_if(iter, end_iter,
333                          BroadcasterClassMatches(
334                              event_spec.GetBroadcasterClass()))) != end_iter) {
335     available_bits &= ~((*iter).first.GetEventBits());
336     iter++;
337   }
338 
339   if (available_bits != 0) {
340     m_event_map.insert(event_listener_key(
341         BroadcastEventSpec(event_spec.GetBroadcasterClass(), available_bits),
342         listener_sp));
343     m_listeners.insert(listener_sp);
344   }
345 
346   return available_bits;
347 }
348 
349 bool BroadcasterManager::UnregisterListenerForEvents(
350     const lldb::ListenerSP &listener_sp, const BroadcastEventSpec &event_spec) {
351   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
352   bool removed_some = false;
353 
354   if (m_listeners.erase(listener_sp) == 0)
355     return false;
356 
357   ListenerMatchesAndSharedBits predicate(event_spec, listener_sp);
358   std::vector<BroadcastEventSpec> to_be_readded;
359   uint32_t event_bits_to_remove = event_spec.GetEventBits();
360 
361   // Go through the map and delete the exact matches, and build a list of
362   // matches that weren't exact to re-add:
363   while (true) {
364     collection::iterator iter, end_iter = m_event_map.end();
365     iter = find_if(m_event_map.begin(), end_iter, predicate);
366     if (iter == end_iter) {
367       break;
368     }
369     uint32_t iter_event_bits = (*iter).first.GetEventBits();
370     removed_some = true;
371 
372     if (event_bits_to_remove != iter_event_bits) {
373       uint32_t new_event_bits = iter_event_bits & ~event_bits_to_remove;
374       to_be_readded.emplace_back(event_spec.GetBroadcasterClass(),
375                                  new_event_bits);
376     }
377     m_event_map.erase(iter);
378   }
379 
380   // Okay now add back the bits that weren't completely removed:
381   for (size_t i = 0; i < to_be_readded.size(); i++) {
382     m_event_map.insert(event_listener_key(to_be_readded[i], listener_sp));
383   }
384 
385   return removed_some;
386 }
387 
388 ListenerSP BroadcasterManager::GetListenerForEventSpec(
389     const BroadcastEventSpec &event_spec) const {
390   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
391 
392   collection::const_iterator iter, end_iter = m_event_map.end();
393   iter = find_if(m_event_map.begin(), end_iter,
394                  BroadcastEventSpecMatches(event_spec));
395   if (iter != end_iter)
396     return (*iter).second;
397 
398   return nullptr;
399 }
400 
401 void BroadcasterManager::RemoveListener(Listener *listener) {
402   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
403   ListenerMatchesPointer predicate(listener);
404   listener_collection::iterator iter = m_listeners.begin(),
405                                 end_iter = m_listeners.end();
406 
407   iter = std::find_if(iter, end_iter, predicate);
408   if (iter != end_iter)
409     m_listeners.erase(iter);
410 
411   while (true) {
412     collection::iterator iter, end_iter = m_event_map.end();
413     iter = find_if(m_event_map.begin(), end_iter, predicate);
414     if (iter == end_iter)
415       break;
416 
417     m_event_map.erase(iter);
418   }
419 }
420 
421 void BroadcasterManager::RemoveListener(const lldb::ListenerSP &listener_sp) {
422   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
423   ListenerMatches predicate(listener_sp);
424 
425   if (m_listeners.erase(listener_sp) == 0)
426     return;
427 
428   while (true) {
429     collection::iterator iter, end_iter = m_event_map.end();
430     iter = find_if(m_event_map.begin(), end_iter, predicate);
431     if (iter == end_iter)
432       break;
433 
434     m_event_map.erase(iter);
435   }
436 }
437 
438 void BroadcasterManager::SignUpListenersForBroadcaster(
439     Broadcaster &broadcaster) {
440   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
441 
442   collection::iterator iter = m_event_map.begin(), end_iter = m_event_map.end();
443 
444   while (iter != end_iter &&
445          (iter = find_if(iter, end_iter,
446                          BroadcasterClassMatches(
447                              broadcaster.GetBroadcasterClass()))) != end_iter) {
448     (*iter).second->StartListeningForEvents(&broadcaster,
449                                             (*iter).first.GetEventBits());
450     iter++;
451   }
452 }
453 
454 void BroadcasterManager::Clear() {
455   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
456   listener_collection::iterator end_iter = m_listeners.end();
457 
458   for (listener_collection::iterator iter = m_listeners.begin();
459        iter != end_iter; iter++)
460     (*iter)->BroadcasterManagerWillDestruct(this->shared_from_this());
461   m_listeners.clear();
462   m_event_map.clear();
463 }
464