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2a14c06435
Non-recursive mutexes encourage better locking discipline and avoid bugs like #96750, where one can unexpectedly re-enter the critical section on the same thread, and interrupt a presumed-indivisible operation. In this case, the only needed fix was to remove locking from some BroadcastManager functions, which were only called from the Listener class (and the listener already locked those mutexes to preserve lock ordering). While doing that, I noticed we don't have unit tests for these functions, so I added one.
551 lines
18 KiB
C++
551 lines
18 KiB
C++
//===-- Broadcaster.cpp ---------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "lldb/Utility/Broadcaster.h"
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#include "lldb/Utility/Event.h"
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#include "lldb/Utility/LLDBLog.h"
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#include "lldb/Utility/Listener.h"
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#include "lldb/Utility/Stream.h"
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#include "lldb/Utility/StreamString.h"
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#include <algorithm>
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#include <memory>
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#include <utility>
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#include <cassert>
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#include <cstddef>
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using namespace lldb;
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using namespace lldb_private;
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Broadcaster::Broadcaster(BroadcasterManagerSP manager_sp, std::string name)
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: m_broadcaster_sp(std::make_shared<BroadcasterImpl>(*this)),
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m_manager_sp(std::move(manager_sp)), m_broadcaster_name(std::move(name)) {
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Log *log = GetLog(LLDBLog::Object);
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LLDB_LOG(log, "{0} Broadcaster::Broadcaster(\"{1}\")",
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static_cast<void *>(this), GetBroadcasterName());
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}
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Broadcaster::BroadcasterImpl::BroadcasterImpl(Broadcaster &broadcaster)
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: m_broadcaster(broadcaster), m_listeners(), m_listeners_mutex(),
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m_hijacking_listeners(), m_hijacking_masks() {}
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Broadcaster::~Broadcaster() {
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Log *log = GetLog(LLDBLog::Object);
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LLDB_LOG(log, "{0} Broadcaster::~Broadcaster(\"{1}\")",
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static_cast<void *>(this), GetBroadcasterName());
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Clear();
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}
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void Broadcaster::CheckInWithManager() {
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if (m_manager_sp) {
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m_manager_sp->SignUpListenersForBroadcaster(*this);
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}
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}
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llvm::SmallVector<std::pair<ListenerSP, uint32_t &>, 4>
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Broadcaster::BroadcasterImpl::GetListeners(uint32_t event_mask,
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bool include_primary) {
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llvm::SmallVector<std::pair<ListenerSP, uint32_t &>, 4> listeners;
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size_t max_count = m_listeners.size();
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if (include_primary)
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max_count++;
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listeners.reserve(max_count);
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for (auto it = m_listeners.begin(); it != m_listeners.end();) {
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lldb::ListenerSP curr_listener_sp(it->first.lock());
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if (curr_listener_sp) {
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if (it->second & event_mask)
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listeners.emplace_back(std::move(curr_listener_sp), it->second);
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++it;
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} else
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// If our listener_wp didn't resolve, then we should remove this entry.
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it = m_listeners.erase(it);
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}
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if (include_primary && m_primary_listener_sp)
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listeners.emplace_back(m_primary_listener_sp, m_primary_listener_mask);
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return listeners;
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}
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bool Broadcaster::BroadcasterImpl::HasListeners(uint32_t event_mask) {
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if (m_primary_listener_sp)
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return true;
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for (auto it = m_listeners.begin(); it != m_listeners.end(); it++) {
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// Don't return a listener if the other end of the WP is gone:
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lldb::ListenerSP curr_listener_sp(it->first.lock());
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if (curr_listener_sp && (it->second & event_mask))
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return true;
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}
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return false;
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}
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void Broadcaster::BroadcasterImpl::Clear() {
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std::lock_guard<std::mutex> guard(m_listeners_mutex);
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// Make sure the listener forgets about this broadcaster. We do this in the
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// broadcaster in case the broadcaster object initiates the removal.
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for (auto &pair : GetListeners())
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pair.first->BroadcasterWillDestruct(&m_broadcaster);
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m_listeners.clear();
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m_primary_listener_sp.reset();
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}
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Broadcaster *Broadcaster::BroadcasterImpl::GetBroadcaster() {
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return &m_broadcaster;
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}
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bool Broadcaster::BroadcasterImpl::GetEventNames(
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Stream &s, uint32_t event_mask, bool prefix_with_broadcaster_name) const {
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uint32_t num_names_added = 0;
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if (event_mask && !m_event_names.empty()) {
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event_names_map::const_iterator end = m_event_names.end();
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for (uint32_t bit = 1u, mask = event_mask; mask != 0 && bit != 0;
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bit <<= 1, mask >>= 1) {
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if (mask & 1) {
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event_names_map::const_iterator pos = m_event_names.find(bit);
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if (pos != end) {
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if (num_names_added > 0)
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s.PutCString(", ");
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if (prefix_with_broadcaster_name) {
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s.PutCString(GetBroadcasterName());
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s.PutChar('.');
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}
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s.PutCString(pos->second);
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++num_names_added;
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}
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}
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}
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}
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return num_names_added > 0;
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}
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void Broadcaster::AddInitialEventsToListener(
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const lldb::ListenerSP &listener_sp, uint32_t requested_events) {}
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uint32_t
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Broadcaster::BroadcasterImpl::AddListener(const lldb::ListenerSP &listener_sp,
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uint32_t event_mask) {
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if (!listener_sp)
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return 0;
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std::lock_guard<std::mutex> guard(m_listeners_mutex);
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// See if we already have this listener, and if so, update its mask
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bool handled = false;
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if (listener_sp == m_primary_listener_sp)
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// This already handles all bits so just return the mask:
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return event_mask;
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for (auto &pair : GetListeners(UINT32_MAX, false)) {
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if (pair.first == listener_sp) {
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handled = true;
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pair.second |= event_mask;
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m_broadcaster.AddInitialEventsToListener(listener_sp, event_mask);
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break;
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}
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}
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if (!handled) {
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// Grant a new listener the available event bits
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m_listeners.push_back(
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std::make_pair(lldb::ListenerWP(listener_sp), event_mask));
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// Individual broadcasters decide whether they have outstanding data when a
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// listener attaches, and insert it into the listener with this method.
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m_broadcaster.AddInitialEventsToListener(listener_sp, event_mask);
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}
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// Return the event bits that were granted to the listener
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return event_mask;
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}
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bool Broadcaster::BroadcasterImpl::EventTypeHasListeners(uint32_t event_type) {
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std::lock_guard<std::mutex> guard(m_listeners_mutex);
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if (!m_hijacking_listeners.empty() && event_type & m_hijacking_masks.back())
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return true;
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// The primary listener listens for all event bits:
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if (m_primary_listener_sp)
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return true;
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return HasListeners(event_type);
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}
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bool Broadcaster::BroadcasterImpl::RemoveListener(
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lldb_private::Listener *listener, uint32_t event_mask) {
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if (!listener)
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return false;
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if (listener == m_primary_listener_sp.get()) {
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// Primary listeners listen for all the event bits for their broadcaster,
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// so remove this altogether if asked:
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m_primary_listener_sp.reset();
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return true;
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}
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std::lock_guard<std::mutex> guard(m_listeners_mutex);
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for (auto it = m_listeners.begin(); it != m_listeners.end();) {
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lldb::ListenerSP curr_listener_sp(it->first.lock());
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if (!curr_listener_sp) {
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// The weak pointer for this listener didn't resolve, lets' prune it
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// as we go.
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it = m_listeners.erase(it);
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continue;
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}
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if (curr_listener_sp.get() == listener) {
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it->second &= ~event_mask;
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// If we removed all the event bits from a listener, remove it from
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// the list as well.
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if (!it->second)
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m_listeners.erase(it);
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return true;
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}
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it++;
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}
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return false;
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}
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bool Broadcaster::BroadcasterImpl::RemoveListener(
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const lldb::ListenerSP &listener_sp, uint32_t event_mask) {
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return RemoveListener(listener_sp.get(), event_mask);
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}
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void Broadcaster::BroadcasterImpl::BroadcastEvent(EventSP &event_sp) {
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return PrivateBroadcastEvent(event_sp, false);
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}
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void Broadcaster::BroadcasterImpl::BroadcastEventIfUnique(EventSP &event_sp) {
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return PrivateBroadcastEvent(event_sp, true);
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}
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void Broadcaster::BroadcasterImpl::PrivateBroadcastEvent(EventSP &event_sp,
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bool unique) {
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// Can't add a nullptr event...
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if (!event_sp)
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return;
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// Update the broadcaster on this event
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event_sp->SetBroadcaster(&m_broadcaster);
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const uint32_t event_type = event_sp->GetType();
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std::lock_guard<std::mutex> guard(m_listeners_mutex);
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ListenerSP hijacking_listener_sp;
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if (!m_hijacking_listeners.empty()) {
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assert(!m_hijacking_masks.empty());
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hijacking_listener_sp = m_hijacking_listeners.back();
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if ((event_type & m_hijacking_masks.back()) == 0)
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hijacking_listener_sp.reset();
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}
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Log *log = GetLog(LLDBLog::Events);
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if (!log && event_sp->GetData())
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log = event_sp->GetData()->GetLogChannel();
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if (log) {
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StreamString event_description;
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event_sp->Dump(&event_description);
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LLDB_LOG(log,
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"{0:x} Broadcaster(\"{1}\")::BroadcastEvent (event_sp = {2}, "
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"unique={3}) hijack = {4:x}",
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static_cast<void *>(this), GetBroadcasterName(),
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event_description.GetData(), unique,
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static_cast<void *>(hijacking_listener_sp.get()));
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}
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ListenerSP primary_listener_sp
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= hijacking_listener_sp ? hijacking_listener_sp : m_primary_listener_sp;
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if (primary_listener_sp) {
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if (unique && primary_listener_sp->PeekAtNextEventForBroadcasterWithType(
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&m_broadcaster, event_type))
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return;
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// Add the pending listeners but not if the event is hijacked, since that
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// is given sole access to the event stream it is hijacking.
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// Make sure to do this before adding the event to the primary or it might
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// start handling the event before we're done adding all the pending
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// listeners.
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// Also, don't redo the check for unique here, since otherwise that could
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// be racy, and if we send the event to the primary listener then we SHOULD
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// send it to the secondary listeners or they will get out of sync with the
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// primary listener.
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if (!hijacking_listener_sp) {
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for (auto &pair : GetListeners(event_type, false))
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event_sp->AddPendingListener(pair.first);
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}
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primary_listener_sp->AddEvent(event_sp);
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} else {
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for (auto &pair : GetListeners(event_type)) {
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if (unique && pair.first->PeekAtNextEventForBroadcasterWithType(
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&m_broadcaster, event_type))
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continue;
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pair.first->AddEvent(event_sp);
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}
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}
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}
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void Broadcaster::BroadcasterImpl::BroadcastEvent(uint32_t event_type) {
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auto event_sp = std::make_shared<Event>(event_type, /*data = */ nullptr);
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PrivateBroadcastEvent(event_sp, false);
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}
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void Broadcaster::BroadcasterImpl::BroadcastEvent(
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uint32_t event_type, const lldb::EventDataSP &event_data_sp) {
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auto event_sp = std::make_shared<Event>(event_type, event_data_sp);
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PrivateBroadcastEvent(event_sp, false);
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}
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void Broadcaster::BroadcasterImpl::BroadcastEventIfUnique(uint32_t event_type) {
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auto event_sp = std::make_shared<Event>(event_type, /*data = */ nullptr);
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PrivateBroadcastEvent(event_sp, true);
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}
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void Broadcaster::BroadcasterImpl::SetPrimaryListener(lldb::ListenerSP
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listener_sp) {
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// This might have already been added as a normal listener, make sure we
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// don't hold two copies.
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RemoveListener(listener_sp.get(), UINT32_MAX);
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m_primary_listener_sp = listener_sp;
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}
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bool Broadcaster::BroadcasterImpl::HijackBroadcaster(
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const lldb::ListenerSP &listener_sp, uint32_t event_mask) {
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std::lock_guard<std::mutex> guard(m_listeners_mutex);
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Log *log = GetLog(LLDBLog::Events);
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LLDB_LOG(
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log,
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"{0} Broadcaster(\"{1}\")::HijackBroadcaster (listener(\"{2}\")={3})",
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static_cast<void *>(this), GetBroadcasterName(),
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listener_sp->m_name.c_str(), static_cast<void *>(listener_sp.get()));
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m_hijacking_listeners.push_back(listener_sp);
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m_hijacking_masks.push_back(event_mask);
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return true;
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}
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bool Broadcaster::BroadcasterImpl::IsHijackedForEvent(uint32_t event_mask) {
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std::lock_guard<std::mutex> guard(m_listeners_mutex);
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if (!m_hijacking_listeners.empty())
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return (event_mask & m_hijacking_masks.back()) != 0;
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return false;
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}
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const char *Broadcaster::BroadcasterImpl::GetHijackingListenerName() {
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if (m_hijacking_listeners.size()) {
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return m_hijacking_listeners.back()->GetName();
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}
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return nullptr;
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}
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void Broadcaster::BroadcasterImpl::RestoreBroadcaster() {
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std::lock_guard<std::mutex> guard(m_listeners_mutex);
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if (!m_hijacking_listeners.empty()) {
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ListenerSP listener_sp = m_hijacking_listeners.back();
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Log *log = GetLog(LLDBLog::Events);
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LLDB_LOG(log,
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"{0} Broadcaster(\"{1}\")::RestoreBroadcaster (about to pop "
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"listener(\"{2}\")={3})",
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static_cast<void *>(this), GetBroadcasterName(),
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listener_sp->m_name.c_str(),
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static_cast<void *>(listener_sp.get()));
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m_hijacking_listeners.pop_back();
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}
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if (!m_hijacking_masks.empty())
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m_hijacking_masks.pop_back();
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}
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llvm::StringRef Broadcaster::GetBroadcasterClass() const {
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static constexpr llvm::StringLiteral class_name("lldb.anonymous");
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return class_name;
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}
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bool BroadcastEventSpec::operator<(const BroadcastEventSpec &rhs) const {
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if (GetBroadcasterClass() == rhs.GetBroadcasterClass()) {
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return GetEventBits() < rhs.GetEventBits();
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}
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return GetBroadcasterClass() < rhs.GetBroadcasterClass();
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}
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BroadcasterManager::BroadcasterManager() : m_manager_mutex() {}
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lldb::BroadcasterManagerSP BroadcasterManager::MakeBroadcasterManager() {
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return lldb::BroadcasterManagerSP(new BroadcasterManager());
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}
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uint32_t BroadcasterManager::RegisterListenerForEventsNoLock(
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const lldb::ListenerSP &listener_sp, const BroadcastEventSpec &event_spec) {
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collection::iterator iter = m_event_map.begin(), end_iter = m_event_map.end();
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uint32_t available_bits = event_spec.GetEventBits();
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auto class_matches = [&event_spec](const event_listener_key &input) -> bool {
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return input.first.GetBroadcasterClass() ==
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event_spec.GetBroadcasterClass();
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};
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while (iter != end_iter &&
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(iter = find_if(iter, end_iter, class_matches)) != end_iter) {
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available_bits &= ~((*iter).first.GetEventBits());
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iter++;
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}
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if (available_bits != 0) {
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m_event_map.insert(event_listener_key(
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BroadcastEventSpec(event_spec.GetBroadcasterClass(), available_bits),
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listener_sp));
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m_listeners.insert(listener_sp);
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}
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return available_bits;
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}
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bool BroadcasterManager::UnregisterListenerForEventsNoLock(
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const lldb::ListenerSP &listener_sp, const BroadcastEventSpec &event_spec) {
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bool removed_some = false;
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if (m_listeners.erase(listener_sp) == 0)
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return false;
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auto listener_matches_and_shared_bits =
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[&listener_sp, &event_spec](const event_listener_key &input) -> bool {
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return input.first.GetBroadcasterClass() ==
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event_spec.GetBroadcasterClass() &&
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(input.first.GetEventBits() & event_spec.GetEventBits()) != 0 &&
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input.second == listener_sp;
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};
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std::vector<BroadcastEventSpec> to_be_readded;
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uint32_t event_bits_to_remove = event_spec.GetEventBits();
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// Go through the map and delete the exact matches, and build a list of
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// matches that weren't exact to re-add:
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for (auto iter = m_event_map.begin(), end = m_event_map.end();;) {
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iter = find_if(iter, end, listener_matches_and_shared_bits);
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if (iter == end)
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break;
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uint32_t iter_event_bits = (*iter).first.GetEventBits();
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removed_some = true;
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if (event_bits_to_remove != iter_event_bits) {
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uint32_t new_event_bits = iter_event_bits & ~event_bits_to_remove;
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to_be_readded.emplace_back(event_spec.GetBroadcasterClass(),
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new_event_bits);
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}
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iter = m_event_map.erase(iter);
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}
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// Okay now add back the bits that weren't completely removed:
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for (const auto &event : to_be_readded) {
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m_event_map.insert(event_listener_key(event, listener_sp));
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}
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return removed_some;
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}
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ListenerSP BroadcasterManager::GetListenerForEventSpec(
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const BroadcastEventSpec &event_spec) const {
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std::lock_guard<std::mutex> guard(m_manager_mutex);
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auto event_spec_matches =
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[&event_spec](const event_listener_key &input) -> bool {
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return input.first.IsContainedIn(event_spec);
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};
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auto iter = llvm::find_if(m_event_map, event_spec_matches);
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if (iter != m_event_map.end())
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return (*iter).second;
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return nullptr;
|
|
}
|
|
|
|
void BroadcasterManager::RemoveListener(Listener *listener) {
|
|
std::lock_guard<std::mutex> guard(m_manager_mutex);
|
|
auto listeners_predicate =
|
|
[&listener](const lldb::ListenerSP &input) -> bool {
|
|
return input.get() == listener;
|
|
};
|
|
|
|
if (auto iter = llvm::find_if(m_listeners, listeners_predicate);
|
|
iter != m_listeners.end())
|
|
m_listeners.erase(iter);
|
|
|
|
auto events_predicate = [listener](const event_listener_key &input) -> bool {
|
|
return input.second.get() == listener;
|
|
};
|
|
|
|
// TODO: use 'std::map::erase_if' when moving to c++20.
|
|
for (auto iter = m_event_map.begin(), end = m_event_map.end();;) {
|
|
iter = find_if(iter, end, events_predicate);
|
|
if (iter == end)
|
|
break;
|
|
|
|
iter = m_event_map.erase(iter);
|
|
}
|
|
}
|
|
|
|
void BroadcasterManager::RemoveListener(const lldb::ListenerSP &listener_sp) {
|
|
std::lock_guard<std::mutex> guard(m_manager_mutex);
|
|
|
|
auto listener_matches =
|
|
[&listener_sp](const event_listener_key &input) -> bool {
|
|
return input.second == listener_sp;
|
|
};
|
|
|
|
if (m_listeners.erase(listener_sp) == 0)
|
|
return;
|
|
|
|
// TODO: use 'std::map::erase_if' when moving to c++20.
|
|
for (auto iter = m_event_map.begin(), end_iter = m_event_map.end();;) {
|
|
iter = find_if(iter, end_iter, listener_matches);
|
|
if (iter == end_iter)
|
|
break;
|
|
|
|
iter = m_event_map.erase(iter);
|
|
}
|
|
}
|
|
|
|
void BroadcasterManager::SignUpListenersForBroadcaster(
|
|
Broadcaster &broadcaster) {
|
|
std::lock_guard<std::mutex> guard(m_manager_mutex);
|
|
|
|
collection::iterator iter = m_event_map.begin(), end_iter = m_event_map.end();
|
|
|
|
auto class_matches = [&broadcaster](const event_listener_key &input) -> bool {
|
|
return input.first.GetBroadcasterClass() ==
|
|
broadcaster.GetBroadcasterClass();
|
|
};
|
|
|
|
while (iter != end_iter &&
|
|
(iter = find_if(iter, end_iter, class_matches)) != end_iter) {
|
|
(*iter).second->StartListeningForEvents(&broadcaster,
|
|
(*iter).first.GetEventBits());
|
|
iter++;
|
|
}
|
|
}
|
|
|
|
void BroadcasterManager::Clear() {
|
|
std::lock_guard<std::mutex> guard(m_manager_mutex);
|
|
|
|
for (auto &listener : m_listeners)
|
|
listener->BroadcasterManagerWillDestruct(this->shared_from_this());
|
|
m_listeners.clear();
|
|
m_event_map.clear();
|
|
}
|