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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2020 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <validationinterface.h>
#include <chain.h>
#include <consensus/validation.h>
#include <logging.h>
#include <primitives/block.h>
#include <primitives/transaction.h>
#include <scheduler.h>
#include <future>
#include <unordered_map>
#include <utility>
/**
* MainSignalsImpl manages a list of shared_ptr<CValidationInterface> callbacks.
*
* A std::unordered_map is used to track what callbacks are currently
* registered, and a std::list is used to store the callbacks that are
* currently registered as well as any callbacks that are just unregistered
* and about to be deleted when they are done executing.
*/
class MainSignalsImpl
{
private:
Mutex m_mutex;
//! List entries consist of a callback pointer and reference count. The
//! count is equal to the number of current executions of that entry, plus 1
//! if it's registered. It cannot be 0 because that would imply it is
//! unregistered and also not being executed (so shouldn't exist).
struct ListEntry { std::shared_ptr<CValidationInterface> callbacks; int count = 1; };
std::list<ListEntry> m_list GUARDED_BY(m_mutex);
std::unordered_map<CValidationInterface*, std::list<ListEntry>::iterator> m_map GUARDED_BY(m_mutex);
public:
// We are not allowed to assume the scheduler only runs in one thread,
// but must ensure all callbacks happen in-order, so we end up creating
// our own queue here :(
SingleThreadedSchedulerClient m_schedulerClient;
explicit MainSignalsImpl(CScheduler& scheduler LIFETIMEBOUND) : m_schedulerClient(scheduler) {}
void Register(std::shared_ptr<CValidationInterface> callbacks)
{
LOCK(m_mutex);
auto inserted = m_map.emplace(callbacks.get(), m_list.end());
if (inserted.second) inserted.first->second = m_list.emplace(m_list.end());
inserted.first->second->callbacks = std::move(callbacks);
}
void Unregister(CValidationInterface* callbacks)
{
LOCK(m_mutex);
auto it = m_map.find(callbacks);
if (it != m_map.end()) {
if (!--it->second->count) m_list.erase(it->second);
m_map.erase(it);
}
}
//! Clear unregisters every previously registered callback, erasing every
//! map entry. After this call, the list may still contain callbacks that
//! are currently executing, but it will be cleared when they are done
//! executing.
void Clear()
{
LOCK(m_mutex);
for (const auto& entry : m_map) {
if (!--entry.second->count) m_list.erase(entry.second);
}
m_map.clear();
}
template<typename F> void Iterate(F&& f)
{
WAIT_LOCK(m_mutex, lock);
for (auto it = m_list.begin(); it != m_list.end();) {
++it->count;
{
REVERSE_LOCK(lock);
f(*it->callbacks);
}
it = --it->count ? std::next(it) : m_list.erase(it);
}
}
};
static CMainSignals g_signals;
void CMainSignals::RegisterBackgroundSignalScheduler(CScheduler& scheduler)
{
assert(!m_internals);
m_internals = std::make_unique<MainSignalsImpl>(scheduler);
}
void CMainSignals::UnregisterBackgroundSignalScheduler()
{
m_internals.reset(nullptr);
}
void CMainSignals::FlushBackgroundCallbacks()
{
if (m_internals) {
m_internals->m_schedulerClient.EmptyQueue();
}
}
size_t CMainSignals::CallbacksPending()
{
if (!m_internals) return 0;
return m_internals->m_schedulerClient.CallbacksPending();
}
CMainSignals& GetMainSignals()
{
return g_signals;
}
void RegisterSharedValidationInterface(std::shared_ptr<CValidationInterface> callbacks)
{
// Each connection captures the shared_ptr to ensure that each callback is
// executed before the subscriber is destroyed. For more details see #18338.
g_signals.m_internals->Register(std::move(callbacks));
}
void RegisterValidationInterface(CValidationInterface* callbacks)
{
// Create a shared_ptr with a no-op deleter - CValidationInterface lifecycle
// is managed by the caller.
RegisterSharedValidationInterface({callbacks, [](CValidationInterface*){}});
}
void UnregisterSharedValidationInterface(std::shared_ptr<CValidationInterface> callbacks)
{
UnregisterValidationInterface(callbacks.get());
}
void UnregisterValidationInterface(CValidationInterface* callbacks)
{
if (g_signals.m_internals) {
g_signals.m_internals->Unregister(callbacks);
}
}
void UnregisterAllValidationInterfaces()
{
if (!g_signals.m_internals) {
return;
}
g_signals.m_internals->Clear();
}
void CallFunctionInValidationInterfaceQueue(std::function<void()> func)
{
g_signals.m_internals->m_schedulerClient.AddToProcessQueue(std::move(func));
}
void SyncWithValidationInterfaceQueue()
{
AssertLockNotHeld(cs_main);
// Block until the validation queue drains
std::promise<void> promise;
CallFunctionInValidationInterfaceQueue([&promise] {
promise.set_value();
});
promise.get_future().wait();
}
// Use a macro instead of a function for conditional logging to prevent
// evaluating arguments when logging is not enabled.
//
// NOTE: The lambda captures all local variables by value.
#define ENQUEUE_AND_LOG_EVENT(event, fmt, name, ...) \
do { \
auto local_name = (name); \
LOG_EVENT("Enqueuing " fmt, local_name, __VA_ARGS__); \
m_internals->m_schedulerClient.AddToProcessQueue([=] { \
LOG_EVENT(fmt, local_name, __VA_ARGS__); \
event(); \
}); \
} while (0)
#define LOG_EVENT(fmt, ...) \
LogPrint(BCLog::VALIDATION, fmt "\n", __VA_ARGS__)
void CMainSignals::UpdatedBlockTip(const CBlockIndex *pindexNew, const CBlockIndex *pindexFork, bool fInitialDownload) {
// Dependencies exist that require UpdatedBlockTip events to be delivered in the order in which
// the chain actually updates. One way to ensure this is for the caller to invoke this signal
// in the same critical section where the chain is updated
auto event = [pindexNew, pindexFork, fInitialDownload, this] {
m_internals->Iterate([&](CValidationInterface& callbacks) { callbacks.UpdatedBlockTip(pindexNew, pindexFork, fInitialDownload); });
};
ENQUEUE_AND_LOG_EVENT(event, "%s: new block hash=%s fork block hash=%s (in IBD=%s)", __func__,
pindexNew->GetBlockHash().ToString(),
pindexFork ? pindexFork->GetBlockHash().ToString() : "null",
fInitialDownload);
}
void CMainSignals::TransactionAddedToMempool(const CTransactionRef& tx, uint64_t mempool_sequence) {
auto event = [tx, mempool_sequence, this] {
m_internals->Iterate([&](CValidationInterface& callbacks) { callbacks.TransactionAddedToMempool(tx, mempool_sequence); });
};
ENQUEUE_AND_LOG_EVENT(event, "%s: txid=%s wtxid=%s", __func__,
tx->GetHash().ToString(),
tx->GetWitnessHash().ToString());
}
void CMainSignals::TransactionRemovedFromMempool(const CTransactionRef& tx, MemPoolRemovalReason reason, uint64_t mempool_sequence) {
auto event = [tx, reason, mempool_sequence, this] {
m_internals->Iterate([&](CValidationInterface& callbacks) { callbacks.TransactionRemovedFromMempool(tx, reason, mempool_sequence); });
};
ENQUEUE_AND_LOG_EVENT(event, "%s: txid=%s wtxid=%s", __func__,
tx->GetHash().ToString(),
tx->GetWitnessHash().ToString());
}
void CMainSignals::BlockConnected(const std::shared_ptr<const CBlock> &pblock, const CBlockIndex *pindex) {
auto event = [pblock, pindex, this] {
m_internals->Iterate([&](CValidationInterface& callbacks) { callbacks.BlockConnected(pblock, pindex); });
};
ENQUEUE_AND_LOG_EVENT(event, "%s: block hash=%s block height=%d", __func__,
pblock->GetHash().ToString(),
pindex->nHeight);
}
void CMainSignals::BlockDisconnected(const std::shared_ptr<const CBlock>& pblock, const CBlockIndex* pindex)
{
auto event = [pblock, pindex, this] {
m_internals->Iterate([&](CValidationInterface& callbacks) { callbacks.BlockDisconnected(pblock, pindex); });
};
ENQUEUE_AND_LOG_EVENT(event, "%s: block hash=%s block height=%d", __func__,
pblock->GetHash().ToString(),
pindex->nHeight);
}
void CMainSignals::ChainStateFlushed(const CBlockLocator &locator) {
auto event = [locator, this] {
m_internals->Iterate([&](CValidationInterface& callbacks) { callbacks.ChainStateFlushed(locator); });
};
ENQUEUE_AND_LOG_EVENT(event, "%s: block hash=%s", __func__,
locator.IsNull() ? "null" : locator.vHave.front().ToString());
}
void CMainSignals::BlockChecked(const CBlock& block, const BlockValidationState& state) {
LOG_EVENT("%s: block hash=%s state=%s", __func__,
block.GetHash().ToString(), state.ToString());
m_internals->Iterate([&](CValidationInterface& callbacks) { callbacks.BlockChecked(block, state); });
}
void CMainSignals::NewPoWValidBlock(const CBlockIndex *pindex, const std::shared_ptr<const CBlock> &block) {
LOG_EVENT("%s: block hash=%s", __func__, block->GetHash().ToString());
m_internals->Iterate([&](CValidationInterface& callbacks) { callbacks.NewPoWValidBlock(pindex, block); });
}
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