1 //===-- Broadcaster.cpp -----------------------------------------*- C++ -*-===//
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 
11 #include "lldb/Utility/Event.h"
12 #include "lldb/Utility/Listener.h"
13 #include "lldb/Utility/Log.h"
14 #include "lldb/Utility/Logging.h"
15 #include "lldb/Utility/Stream.h"
16 #include "lldb/Utility/StreamString.h"
17 
18 #include <algorithm>
19 #include <memory>
20 #include <type_traits>
21 
22 #include <assert.h>
23 #include <stddef.h>
24 
25 using namespace lldb;
26 using namespace lldb_private;
27 
28 Broadcaster::Broadcaster(BroadcasterManagerSP manager_sp, const char *name)
29     : m_broadcaster_sp(std::make_shared<BroadcasterImpl>(*this)),
30       m_manager_sp(manager_sp), m_broadcaster_name(name) {
31   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_OBJECT));
32   if (log)
33     log->Printf("%p Broadcaster::Broadcaster(\"%s\")",
34                 static_cast<void *>(this), GetBroadcasterName().AsCString());
35 }
36 
37 Broadcaster::BroadcasterImpl::BroadcasterImpl(Broadcaster &broadcaster)
38     : m_broadcaster(broadcaster), m_listeners(), m_listeners_mutex(),
39       m_hijacking_listeners(), m_hijacking_masks() {}
40 
41 Broadcaster::~Broadcaster() {
42   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_OBJECT));
43   if (log)
44     log->Printf("%p Broadcaster::~Broadcaster(\"%s\")",
45                 static_cast<void *>(this), m_broadcaster_name.AsCString());
46 
47   Clear();
48 }
49 
50 void Broadcaster::CheckInWithManager() {
51   if (m_manager_sp) {
52     m_manager_sp->SignUpListenersForBroadcaster(*this);
53   }
54 }
55 
56 llvm::SmallVector<std::pair<ListenerSP, uint32_t &>, 4>
57 Broadcaster::BroadcasterImpl::GetListeners() {
58   llvm::SmallVector<std::pair<ListenerSP, uint32_t &>, 4> listeners;
59   listeners.reserve(m_listeners.size());
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 && it->second) {
64       listeners.emplace_back(std::move(curr_listener_sp), it->second);
65       ++it;
66     } else
67       it = m_listeners.erase(it);
68   }
69 
70   return listeners;
71 }
72 
73 void Broadcaster::BroadcasterImpl::Clear() {
74   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
75 
76   // Make sure the listener forgets about this broadcaster. We do this in the
77   // broadcaster in case the broadcaster object initiates the removal.
78   for (auto &pair : GetListeners())
79     pair.first->BroadcasterWillDestruct(&m_broadcaster);
80 
81   m_listeners.clear();
82 }
83 
84 Broadcaster *Broadcaster::BroadcasterImpl::GetBroadcaster() {
85   return &m_broadcaster;
86 }
87 
88 bool Broadcaster::BroadcasterImpl::GetEventNames(
89     Stream &s, uint32_t event_mask, bool prefix_with_broadcaster_name) const {
90   uint32_t num_names_added = 0;
91   if (event_mask && !m_event_names.empty()) {
92     event_names_map::const_iterator end = m_event_names.end();
93     for (uint32_t bit = 1u, mask = event_mask; mask != 0 && bit != 0;
94          bit <<= 1, mask >>= 1) {
95       if (mask & 1) {
96         event_names_map::const_iterator pos = m_event_names.find(bit);
97         if (pos != end) {
98           if (num_names_added > 0)
99             s.PutCString(", ");
100 
101           if (prefix_with_broadcaster_name) {
102             s.PutCString(GetBroadcasterName());
103             s.PutChar('.');
104           }
105           s.PutCString(pos->second);
106           ++num_names_added;
107         }
108       }
109     }
110   }
111   return num_names_added > 0;
112 }
113 
114 void Broadcaster::AddInitialEventsToListener(
115     const lldb::ListenerSP &listener_sp, uint32_t requested_events) {}
116 
117 uint32_t
118 Broadcaster::BroadcasterImpl::AddListener(const lldb::ListenerSP &listener_sp,
119                                           uint32_t event_mask) {
120   if (!listener_sp)
121     return 0;
122 
123   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
124 
125   // See if we already have this listener, and if so, update its mask
126 
127   bool handled = false;
128 
129   for (auto &pair : GetListeners()) {
130     if (pair.first == listener_sp) {
131       handled = true;
132       pair.second |= event_mask;
133       m_broadcaster.AddInitialEventsToListener(listener_sp, event_mask);
134       break;
135     }
136   }
137 
138   if (!handled) {
139     // Grant a new listener the available event bits
140     m_listeners.push_back(
141         std::make_pair(lldb::ListenerWP(listener_sp), event_mask));
142 
143     // Individual broadcasters decide whether they have outstanding data when a
144     // listener attaches, and insert it into the listener with this method.
145     m_broadcaster.AddInitialEventsToListener(listener_sp, event_mask);
146   }
147 
148   // Return the event bits that were granted to the listener
149   return event_mask;
150 }
151 
152 bool Broadcaster::BroadcasterImpl::EventTypeHasListeners(uint32_t event_type) {
153   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
154 
155   if (!m_hijacking_listeners.empty() && event_type & m_hijacking_masks.back())
156     return true;
157 
158   for (auto &pair : GetListeners()) {
159     if (pair.second & event_type)
160       return true;
161   }
162   return false;
163 }
164 
165 bool Broadcaster::BroadcasterImpl::RemoveListener(
166     lldb_private::Listener *listener, uint32_t event_mask) {
167   if (!listener)
168     return false;
169 
170   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
171   for (auto &pair : GetListeners()) {
172     if (pair.first.get() == listener) {
173       pair.second &= ~event_mask;
174       return true;
175     }
176   }
177   return false;
178 }
179 
180 bool Broadcaster::BroadcasterImpl::RemoveListener(
181     const lldb::ListenerSP &listener_sp, uint32_t event_mask) {
182   return RemoveListener(listener_sp.get(), event_mask);
183 }
184 
185 void Broadcaster::BroadcasterImpl::BroadcastEvent(EventSP &event_sp) {
186   return PrivateBroadcastEvent(event_sp, false);
187 }
188 
189 void Broadcaster::BroadcasterImpl::BroadcastEventIfUnique(EventSP &event_sp) {
190   return PrivateBroadcastEvent(event_sp, true);
191 }
192 
193 void Broadcaster::BroadcasterImpl::PrivateBroadcastEvent(EventSP &event_sp,
194                                                          bool unique) {
195   // Can't add a nullptr event...
196   if (!event_sp)
197     return;
198 
199   // Update the broadcaster on this event
200   event_sp->SetBroadcaster(&m_broadcaster);
201 
202   const uint32_t event_type = event_sp->GetType();
203 
204   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
205 
206   ListenerSP hijacking_listener_sp;
207 
208   if (!m_hijacking_listeners.empty()) {
209     assert(!m_hijacking_masks.empty());
210     hijacking_listener_sp = m_hijacking_listeners.back();
211     if ((event_type & m_hijacking_masks.back()) == 0)
212       hijacking_listener_sp.reset();
213   }
214 
215   Log *log(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_EVENTS));
216   if (log) {
217     StreamString event_description;
218     event_sp->Dump(&event_description);
219     log->Printf("%p Broadcaster(\"%s\")::BroadcastEvent (event_sp = {%s}, "
220                 "unique =%i) hijack = %p",
221                 static_cast<void *>(this), GetBroadcasterName(),
222                 event_description.GetData(), unique,
223                 static_cast<void *>(hijacking_listener_sp.get()));
224   }
225 
226   if (hijacking_listener_sp) {
227     if (unique &&
228         hijacking_listener_sp->PeekAtNextEventForBroadcasterWithType(
229             &m_broadcaster, event_type))
230       return;
231     hijacking_listener_sp->AddEvent(event_sp);
232   } else {
233     for (auto &pair : GetListeners()) {
234       if (!(pair.second & event_type))
235         continue;
236       if (unique &&
237           pair.first->PeekAtNextEventForBroadcasterWithType(&m_broadcaster,
238                                                             event_type))
239         continue;
240 
241       pair.first->AddEvent(event_sp);
242     }
243   }
244 }
245 
246 void Broadcaster::BroadcasterImpl::BroadcastEvent(uint32_t event_type,
247                                                   EventData *event_data) {
248   auto event_sp = std::make_shared<Event>(event_type, event_data);
249   PrivateBroadcastEvent(event_sp, false);
250 }
251 
252 void Broadcaster::BroadcasterImpl::BroadcastEvent(
253     uint32_t event_type, const lldb::EventDataSP &event_data_sp) {
254   auto event_sp = std::make_shared<Event>(event_type, event_data_sp);
255   PrivateBroadcastEvent(event_sp, false);
256 }
257 
258 void Broadcaster::BroadcasterImpl::BroadcastEventIfUnique(
259     uint32_t event_type, EventData *event_data) {
260   auto event_sp = std::make_shared<Event>(event_type, event_data);
261   PrivateBroadcastEvent(event_sp, true);
262 }
263 
264 bool Broadcaster::BroadcasterImpl::HijackBroadcaster(
265     const lldb::ListenerSP &listener_sp, uint32_t event_mask) {
266   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
267 
268   Log *log(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_EVENTS));
269   if (log)
270     log->Printf(
271         "%p Broadcaster(\"%s\")::HijackBroadcaster (listener(\"%s\")=%p)",
272         static_cast<void *>(this), GetBroadcasterName(),
273         listener_sp->m_name.c_str(), static_cast<void *>(listener_sp.get()));
274   m_hijacking_listeners.push_back(listener_sp);
275   m_hijacking_masks.push_back(event_mask);
276   return true;
277 }
278 
279 bool Broadcaster::BroadcasterImpl::IsHijackedForEvent(uint32_t event_mask) {
280   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
281 
282   if (!m_hijacking_listeners.empty())
283     return (event_mask & m_hijacking_masks.back()) != 0;
284   return false;
285 }
286 
287 const char *Broadcaster::BroadcasterImpl::GetHijackingListenerName() {
288   if (m_hijacking_listeners.size()) {
289     return m_hijacking_listeners.back()->GetName();
290   } else {
291     return nullptr;
292   }
293 }
294 
295 void Broadcaster::BroadcasterImpl::RestoreBroadcaster() {
296   std::lock_guard<std::recursive_mutex> guard(m_listeners_mutex);
297 
298   if (!m_hijacking_listeners.empty()) {
299     Log *log(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_EVENTS));
300     if (log) {
301       ListenerSP listener_sp = m_hijacking_listeners.back();
302       log->Printf("%p Broadcaster(\"%s\")::RestoreBroadcaster (about to pop "
303                   "listener(\"%s\")=%p)",
304                   static_cast<void *>(this), GetBroadcasterName(),
305                   listener_sp->m_name.c_str(),
306                   static_cast<void *>(listener_sp.get()));
307     }
308     m_hijacking_listeners.pop_back();
309   }
310   if (!m_hijacking_masks.empty())
311     m_hijacking_masks.pop_back();
312 }
313 
314 ConstString &Broadcaster::GetBroadcasterClass() const {
315   static ConstString class_name("lldb.anonymous");
316   return class_name;
317 }
318 
319 bool BroadcastEventSpec::operator<(const BroadcastEventSpec &rhs) const {
320   if (GetBroadcasterClass() == rhs.GetBroadcasterClass()) {
321     return GetEventBits() < rhs.GetEventBits();
322   } else {
323     return GetBroadcasterClass() < rhs.GetBroadcasterClass();
324   }
325 }
326 
327 BroadcastEventSpec &BroadcastEventSpec::
328 operator=(const BroadcastEventSpec &rhs) = default;
329 
330 BroadcasterManager::BroadcasterManager() : m_manager_mutex() {}
331 
332 lldb::BroadcasterManagerSP BroadcasterManager::MakeBroadcasterManager() {
333   return lldb::BroadcasterManagerSP(new BroadcasterManager());
334 }
335 
336 uint32_t BroadcasterManager::RegisterListenerForEvents(
337     const lldb::ListenerSP &listener_sp, BroadcastEventSpec event_spec) {
338   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
339 
340   collection::iterator iter = m_event_map.begin(), end_iter = m_event_map.end();
341   uint32_t available_bits = event_spec.GetEventBits();
342 
343   while (iter != end_iter &&
344          (iter = find_if(iter, end_iter,
345                          BroadcasterClassMatches(
346                              event_spec.GetBroadcasterClass()))) != end_iter) {
347     available_bits &= ~((*iter).first.GetEventBits());
348     iter++;
349   }
350 
351   if (available_bits != 0) {
352     m_event_map.insert(event_listener_key(
353         BroadcastEventSpec(event_spec.GetBroadcasterClass(), available_bits),
354         listener_sp));
355     m_listeners.insert(listener_sp);
356   }
357 
358   return available_bits;
359 }
360 
361 bool BroadcasterManager::UnregisterListenerForEvents(
362     const lldb::ListenerSP &listener_sp, BroadcastEventSpec event_spec) {
363   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
364   bool removed_some = false;
365 
366   if (m_listeners.erase(listener_sp) == 0)
367     return false;
368 
369   ListenerMatchesAndSharedBits predicate(event_spec, listener_sp);
370   std::vector<BroadcastEventSpec> to_be_readded;
371   uint32_t event_bits_to_remove = event_spec.GetEventBits();
372 
373   // Go through the map and delete the exact matches, and build a list of
374   // matches that weren't exact to re-add:
375   while (true) {
376     collection::iterator iter, end_iter = m_event_map.end();
377     iter = find_if(m_event_map.begin(), end_iter, predicate);
378     if (iter == end_iter) {
379       break;
380     } else {
381       uint32_t iter_event_bits = (*iter).first.GetEventBits();
382       removed_some = true;
383 
384       if (event_bits_to_remove != iter_event_bits) {
385         uint32_t new_event_bits = iter_event_bits & ~event_bits_to_remove;
386         to_be_readded.push_back(BroadcastEventSpec(
387             event_spec.GetBroadcasterClass(), new_event_bits));
388       }
389       m_event_map.erase(iter);
390     }
391   }
392 
393   // Okay now add back the bits that weren't completely removed:
394   for (size_t i = 0; i < to_be_readded.size(); i++) {
395     m_event_map.insert(event_listener_key(to_be_readded[i], listener_sp));
396   }
397 
398   return removed_some;
399 }
400 
401 ListenerSP BroadcasterManager::GetListenerForEventSpec(
402     BroadcastEventSpec event_spec) const {
403   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
404 
405   collection::const_iterator iter, end_iter = m_event_map.end();
406   iter = find_if(m_event_map.begin(), end_iter,
407                  BroadcastEventSpecMatches(event_spec));
408   if (iter != end_iter)
409     return (*iter).second;
410   else
411     return nullptr;
412 }
413 
414 void BroadcasterManager::RemoveListener(Listener *listener) {
415   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
416   ListenerMatchesPointer predicate(listener);
417   listener_collection::iterator iter = m_listeners.begin(),
418                                 end_iter = m_listeners.end();
419 
420   std::find_if(iter, end_iter, predicate);
421   if (iter != end_iter)
422     m_listeners.erase(iter);
423 
424   while (true) {
425     collection::iterator iter, end_iter = m_event_map.end();
426     iter = find_if(m_event_map.begin(), end_iter, predicate);
427     if (iter == end_iter)
428       break;
429     else
430       m_event_map.erase(iter);
431   }
432 }
433 
434 void BroadcasterManager::RemoveListener(const lldb::ListenerSP &listener_sp) {
435   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
436   ListenerMatches predicate(listener_sp);
437 
438   if (m_listeners.erase(listener_sp) == 0)
439     return;
440 
441   while (true) {
442     collection::iterator iter, end_iter = m_event_map.end();
443     iter = find_if(m_event_map.begin(), end_iter, predicate);
444     if (iter == end_iter)
445       break;
446     else
447       m_event_map.erase(iter);
448   }
449 }
450 
451 void BroadcasterManager::SignUpListenersForBroadcaster(
452     Broadcaster &broadcaster) {
453   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
454 
455   collection::iterator iter = m_event_map.begin(), end_iter = m_event_map.end();
456 
457   while (iter != end_iter &&
458          (iter = find_if(iter, end_iter,
459                          BroadcasterClassMatches(
460                              broadcaster.GetBroadcasterClass()))) != end_iter) {
461     (*iter).second->StartListeningForEvents(&broadcaster,
462                                             (*iter).first.GetEventBits());
463     iter++;
464   }
465 }
466 
467 void BroadcasterManager::Clear() {
468   std::lock_guard<std::recursive_mutex> guard(m_manager_mutex);
469   listener_collection::iterator end_iter = m_listeners.end();
470 
471   for (listener_collection::iterator iter = m_listeners.begin();
472        iter != end_iter; iter++)
473     (*iter)->BroadcasterManagerWillDestruct(this->shared_from_this());
474   m_listeners.clear();
475   m_event_map.clear();
476 }
477