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diff --git a/src/rcu.h b/src/rcu.h
index 5a67fcae4..fbd425866 100644
--- a/src/rcu.h
+++ b/src/rcu.h
@@ -1,234 +1,234 @@
// Copyright (c) 2018-2019 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_RCU_H
#define BITCOIN_RCU_H
#include <atomic>
#include <cassert>
#include <cstdint>
#include <functional>
#include <map>
#include <ostream>
#include <type_traits>
#include <utility>
class RCUInfos;
class RCUReadLock;
class RCUInfos {
std::atomic<uint64_t> state;
std::atomic<RCUInfos *> next;
std::map<uint64_t, std::function<void()>> cleanups;
// The largest revision possible means unlocked.
static const uint64_t UNLOCKED = -uint64_t(1);
RCUInfos();
~RCUInfos();
void readLock() {
assert(!isLocked());
state.store(revision.load());
}
void readFree() {
assert(isLocked());
state.store(UNLOCKED);
}
bool isLocked() const { return state.load() != UNLOCKED; }
void registerCleanup(const std::function<void()> &f) {
cleanups.emplace(++revision, f);
}
void synchronize();
void runCleanups();
uint64_t hasSyncedTo(uint64_t cutoff = UNLOCKED);
friend class RCULock;
friend struct RCUTest;
static std::atomic<uint64_t> revision;
static thread_local RCUInfos infos;
};
class RCULock {
RCUInfos *infos;
explicit RCULock(RCUInfos *infosIn) : infos(infosIn) { infos->readLock(); }
friend class RCUInfos;
public:
RCULock() : RCULock(&RCUInfos::infos) {}
~RCULock() { infos->readFree(); }
RCULock(const RCULock &) = delete;
RCULock &operator=(const RCULock &) = delete;
static bool isLocked() { return RCUInfos::infos.isLocked(); }
static void registerCleanup(const std::function<void()> &f) {
RCUInfos::infos.registerCleanup(f);
}
static void synchronize() { RCUInfos::infos.synchronize(); }
};
template <typename T> class RCUPtr {
T *ptr;
// Private construction, so factories have to be used.
explicit RCUPtr(T *ptrIn) : ptr(ptrIn) {}
public:
RCUPtr() : ptr(nullptr) {}
~RCUPtr() {
if (ptr != nullptr) {
- ptr->release();
+ ptr->decrementRefCount();
}
}
/**
* Acquire ownership of some pointer.
*/
static RCUPtr acquire(T *&ptrIn) {
RCUPtr ret(ptrIn);
ptrIn = nullptr;
return ret;
}
/**
* Construct a new object that is owned by the pointer.
*/
template <typename... Args> static RCUPtr make(Args &&...args) {
return RCUPtr(new T(std::forward<Args>(args)...));
}
/**
* Construct a new RCUPtr without transferring owership.
*/
static RCUPtr copy(T *ptr) {
if (ptr != nullptr) {
- ptr->acquire();
+ ptr->incrementRefCount();
}
return RCUPtr::acquire(ptr);
}
/**
* Copy semantic.
*/
RCUPtr(const RCUPtr &src) : ptr(src.ptr) {
if (ptr != nullptr) {
- ptr->acquire();
+ ptr->incrementRefCount();
}
}
RCUPtr &operator=(const RCUPtr &rhs) {
RCUPtr tmp(rhs);
std::swap(ptr, tmp.ptr);
return *this;
}
/**
* Move semantic.
*/
RCUPtr(RCUPtr &&src) : RCUPtr() { std::swap(ptr, src.ptr); }
RCUPtr &operator=(RCUPtr &&rhs) {
std::swap(ptr, rhs.ptr);
return *this;
}
/**
* Get allows to access the undelying pointer. RCUPtr keeps ownership.
*/
T *get() { return ptr; }
const T *get() const { return ptr; }
/**
* Release transfers ownership of the pointer from RCUPtr to the caller.
*/
T *release() {
T *oldPtr = ptr;
ptr = nullptr;
return oldPtr;
}
/**
* Operator overloading for convenience.
*/
T *operator->() { return ptr; }
const T *operator->() const { return ptr; }
T &operator*() { return *ptr; }
const T &operator*() const { return *ptr; }
explicit operator bool() const { return ptr != nullptr; }
/**
* Equality checks.
*/
friend bool operator==(const RCUPtr &lhs, const T *rhs) {
return lhs.get() == rhs;
}
friend bool operator==(const RCUPtr &lhs, const RCUPtr &rhs) {
return lhs == rhs.get();
}
friend bool operator!=(const RCUPtr &lhs, const T *rhs) {
return !(lhs == rhs);
}
friend bool operator!=(const RCUPtr &lhs, const RCUPtr &rhs) {
return !(lhs == rhs);
}
/**
* ostream support.
*/
friend std::ostream &operator<<(std::ostream &stream, const RCUPtr &rhs) {
return stream << rhs.ptr;
}
};
#define IMPLEMENT_RCU_REFCOUNT(T) \
private: \
mutable std::atomic<T> refcount{0}; \
\
- void acquire() const { refcount++; } \
+ void incrementRefCount() const { refcount++; } \
\
bool tryDecrement() const { \
T count = refcount.load(); \
while (count > 0) { \
if (refcount.compare_exchange_weak(count, count - 1)) { \
return true; \
} \
} \
\
return false; \
} \
\
- void release() const { \
+ void decrementRefCount() const { \
if (tryDecrement()) { \
return; \
} \
\
RCULock::registerCleanup([this] { \
if (tryDecrement()) { \
return; \
} \
\
delete this; \
}); \
} \
\
static_assert(std::is_integral<T>::value, "T must be an integral type."); \
static_assert(std::is_unsigned<T>::value, "T must be unsigned."); \
\
template <typename> friend class ::RCUPtr
#endif // BITCOIN_RCU_H
diff --git a/src/test/rcu_tests.cpp b/src/test/rcu_tests.cpp
index 8235deb1b..23a5bd11e 100644
--- a/src/test/rcu_tests.cpp
+++ b/src/test/rcu_tests.cpp
@@ -1,392 +1,392 @@
// Copyright (c) 2018-2019 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <rcu.h>
#include <test/util/setup_common.h>
#include <boost/test/unit_test.hpp>
#include <chrono>
struct RCUTest {
static uint64_t getRevision() { return RCUInfos::revision.load(); }
static uint64_t hasSyncedTo(uint64_t syncRev) {
return RCUInfos::infos.hasSyncedTo(syncRev);
}
static std::map<uint64_t, std::function<void()>> &getCleanups() {
return RCUInfos::infos.cleanups;
}
};
BOOST_FIXTURE_TEST_SUITE(rcu_tests, BasicTestingSetup)
enum RCUTestStep {
Init,
Locked,
LockAck,
RCULocked,
Synchronizing,
Synchronized,
};
#define WAIT_FOR_STEP(step) \
do { \
cond.notify_all(); \
} while (!cond.wait_for(lock, std::chrono::milliseconds(1), \
[&] { return otherstep == step; }))
void synchronize(std::atomic<RCUTestStep> &step,
const std::atomic<RCUTestStep> &otherstep, Mutex &cs,
std::condition_variable &cond,
std::atomic<uint64_t> &syncRev) {
assert(step == RCUTestStep::Init);
{
WAIT_LOCK(cs, lock);
step = RCUTestStep::Locked;
// Wait for our lock to be acknowledged.
WAIT_FOR_STEP(RCUTestStep::LockAck);
RCULock rculock;
// Update step.
step = RCUTestStep::RCULocked;
// Wait for master.
WAIT_FOR_STEP(RCUTestStep::RCULocked);
}
// Update step.
syncRev = RCUTest::getRevision() + 1;
step = RCUTestStep::Synchronizing;
assert(!RCUTest::hasSyncedTo(syncRev));
// We wait for readers.
RCULock::synchronize();
// Update step.
step = RCUTestStep::Synchronized;
}
void lockAndWaitForSynchronize(std::atomic<RCUTestStep> &step,
const std::atomic<RCUTestStep> &otherstep,
Mutex &cs, std::condition_variable &cond,
std::atomic<uint64_t> &syncRev) {
assert(step == RCUTestStep::Init);
WAIT_LOCK(cs, lock);
// Wait for th eother thread to be locked.
WAIT_FOR_STEP(RCUTestStep::Locked);
step = RCUTestStep::LockAck;
// Wait for the synchronizing tread to take its RCU lock.
WAIT_FOR_STEP(RCUTestStep::RCULocked);
assert(!RCUTest::hasSyncedTo(syncRev));
{
RCULock rculock;
// Update master step.
step = RCUTestStep::RCULocked;
while (RCUTest::getRevision() < syncRev) {
WAIT_FOR_STEP(RCUTestStep::Synchronizing);
}
assert(RCUTest::getRevision() >= syncRev);
assert(otherstep.load() == RCUTestStep::Synchronizing);
}
assert(RCUTest::hasSyncedTo(syncRev) >= syncRev);
WAIT_FOR_STEP(RCUTestStep::Synchronized);
}
static const int COUNT = 128;
BOOST_AUTO_TEST_CASE(synchronize_test) {
Mutex cs;
std::condition_variable cond;
std::atomic<RCUTestStep> parentstep;
std::atomic<RCUTestStep> childstep;
std::atomic<uint64_t> syncRev;
for (int i = 0; i < COUNT; i++) {
parentstep = RCUTestStep::Init;
childstep = RCUTestStep::Init;
syncRev = RCUTest::getRevision() + 1;
std::thread tlock([&] {
lockAndWaitForSynchronize(parentstep, childstep, cs, cond, syncRev);
});
std::thread tsync(
[&] { synchronize(childstep, parentstep, cs, cond, syncRev); });
tlock.join();
tsync.join();
}
// Needed to suppress "Test case [...] did not check any assertions"
BOOST_CHECK(true);
}
BOOST_AUTO_TEST_CASE(cleanup_test) {
RCULock::synchronize();
BOOST_CHECK(RCUTest::getCleanups().empty());
bool isClean1 = false;
RCULock::registerCleanup([&] { isClean1 = true; });
BOOST_CHECK(!isClean1);
BOOST_CHECK_EQUAL(RCUTest::getCleanups().size(), 1);
BOOST_CHECK_EQUAL(RCUTest::getRevision(),
RCUTest::getCleanups().begin()->first);
// Synchronize runs the cleanups.
RCULock::synchronize();
BOOST_CHECK(RCUTest::getCleanups().empty());
BOOST_CHECK(isClean1);
// Check multiple callbacks.
isClean1 = false;
bool isClean2 = false;
bool isClean3 = false;
RCULock::registerCleanup([&] { isClean1 = true; });
RCULock::registerCleanup([&] { isClean2 = true; });
RCULock::registerCleanup([&] { isClean3 = true; });
BOOST_CHECK_EQUAL(RCUTest::getCleanups().size(), 3);
RCULock::synchronize();
BOOST_CHECK(RCUTest::getCleanups().empty());
BOOST_CHECK(isClean1);
BOOST_CHECK(isClean2);
BOOST_CHECK(isClean3);
// Check callbacks adding each others.
isClean1 = false;
isClean2 = false;
isClean3 = false;
RCULock::registerCleanup([&] {
isClean1 = true;
RCULock::registerCleanup([&] {
isClean2 = true;
RCULock::registerCleanup([&] { isClean3 = true; });
});
});
BOOST_CHECK_EQUAL(RCUTest::getCleanups().size(), 1);
RCULock::synchronize();
BOOST_CHECK(RCUTest::getCleanups().empty());
BOOST_CHECK(isClean1);
BOOST_CHECK(isClean2);
BOOST_CHECK(isClean3);
}
class RCURefTestItem {
IMPLEMENT_RCU_REFCOUNT(uint32_t);
const std::function<void()> cleanupfun;
public:
explicit RCURefTestItem(const std::function<void()> &fun)
: cleanupfun(fun) {}
~RCURefTestItem() { cleanupfun(); }
uint32_t getRefCount() const { return refcount.load(); }
};
BOOST_AUTO_TEST_CASE(rcuptr_test) {
// Make sure it works for null.
{
RCURefTestItem *ptr = nullptr;
RCUPtr<RCURefTestItem>::copy(ptr);
RCUPtr<RCURefTestItem>::acquire(ptr);
}
// Check the destruction mechanism.
bool isDestroyed = false;
{
auto rcuptr = RCUPtr<RCURefTestItem>::make([&] { isDestroyed = true; });
BOOST_CHECK_EQUAL(rcuptr->getRefCount(), 0);
}
// rcuptr waits for synchronization to destroy.
BOOST_CHECK(!isDestroyed);
RCULock::synchronize();
BOOST_CHECK(isDestroyed);
// Check that copy behaves properly.
isDestroyed = false;
RCUPtr<RCURefTestItem> gptr;
{
auto rcuptr = RCUPtr<RCURefTestItem>::make([&] { isDestroyed = true; });
BOOST_CHECK_EQUAL(rcuptr->getRefCount(), 0);
gptr = rcuptr;
BOOST_CHECK_EQUAL(rcuptr->getRefCount(), 1);
BOOST_CHECK_EQUAL(gptr->getRefCount(), 1);
auto rcuptrcopy = rcuptr;
BOOST_CHECK_EQUAL(rcuptrcopy->getRefCount(), 2);
BOOST_CHECK_EQUAL(rcuptr->getRefCount(), 2);
BOOST_CHECK_EQUAL(gptr->getRefCount(), 2);
}
BOOST_CHECK_EQUAL(gptr->getRefCount(), 0);
RCULock::synchronize();
BOOST_CHECK(!isDestroyed);
gptr = RCUPtr<RCURefTestItem>();
BOOST_CHECK(!isDestroyed);
RCULock::synchronize();
BOOST_CHECK(isDestroyed);
}
BOOST_AUTO_TEST_CASE(rcuptr_operator_test) {
auto gptr = RCUPtr<RCURefTestItem>();
auto ptr = new RCURefTestItem([] {});
auto oldPtr = ptr;
auto altptr = RCUPtr<RCURefTestItem>::make([] {});
// Check various operators.
BOOST_CHECK_EQUAL(gptr.get(), NULLPTR(RCURefTestItem));
BOOST_CHECK_EQUAL(gptr, NULLPTR(RCURefTestItem));
BOOST_CHECK(!gptr);
auto copyptr = gptr;
BOOST_CHECK(gptr == nullptr);
BOOST_CHECK(gptr != oldPtr);
BOOST_CHECK(gptr == copyptr);
BOOST_CHECK(gptr != altptr);
gptr = RCUPtr<RCURefTestItem>::acquire(ptr);
BOOST_CHECK_EQUAL(ptr, NULLPTR(RCURefTestItem));
BOOST_CHECK_EQUAL(gptr.get(), oldPtr);
BOOST_CHECK_EQUAL(&*gptr, oldPtr);
BOOST_CHECK_EQUAL(gptr, oldPtr);
BOOST_CHECK(gptr);
copyptr = gptr;
BOOST_CHECK(gptr != nullptr);
BOOST_CHECK(gptr == oldPtr);
BOOST_CHECK(gptr == copyptr);
BOOST_CHECK(gptr != altptr);
}
BOOST_AUTO_TEST_CASE(const_rcuptr_test) {
bool isDestroyed = false;
auto ptr = RCUPtr<const RCURefTestItem>::make([&] { isDestroyed = true; });
// Now let's destroy it.
ptr = RCUPtr<const RCURefTestItem>();
BOOST_CHECK(!isDestroyed);
RCULock::synchronize();
BOOST_CHECK(isDestroyed);
}
class RCURefMoveTestItem {
const std::function<void()> cleanupfun;
public:
explicit RCURefMoveTestItem(const std::function<void()> &fun)
: cleanupfun(fun) {}
~RCURefMoveTestItem() { cleanupfun(); }
- void acquire() {
+ void incrementRefCount() {
throw std::runtime_error("RCUPtr incremented the refcount");
}
- void release() {
+ void decrementRefCount() {
RCULock::registerCleanup([this] { delete this; });
}
};
BOOST_AUTO_TEST_CASE(move_rcuptr_test) {
bool isDestroyed = false;
// Check tat copy is failing.
auto rcuptr1 =
RCUPtr<RCURefMoveTestItem>::make([&] { isDestroyed = true; });
- BOOST_CHECK_THROW(rcuptr1->acquire(), std::runtime_error);
+ BOOST_CHECK_THROW(rcuptr1->incrementRefCount(), std::runtime_error);
BOOST_CHECK_THROW(auto rcuptrcopy = rcuptr1;, std::runtime_error);
// Try to move.
auto rcuptr2 = std::move(rcuptr1);
RCULock::synchronize();
BOOST_CHECK(!isDestroyed);
// Move to a local and check proper destruction.
{ auto rcuptr3 = std::move(rcuptr2); }
BOOST_CHECK(!isDestroyed);
RCULock::synchronize();
BOOST_CHECK(isDestroyed);
// Let's try to swap.
isDestroyed = false;
rcuptr1 = RCUPtr<RCURefMoveTestItem>::make([&] { isDestroyed = true; });
std::swap(rcuptr1, rcuptr2);
RCULock::synchronize();
BOOST_CHECK(!isDestroyed);
// Chain moves to make sure there are no double free.
{
auto rcuptr3 = std::move(rcuptr2);
auto rcuptr4 = std::move(rcuptr3);
std::swap(rcuptr1, rcuptr4);
}
RCULock::synchronize();
BOOST_CHECK(!isDestroyed);
// Check we can return from a function.
{
auto r = ([&] {
auto moved = std::move(rcuptr1);
return moved;
})();
RCULock::synchronize();
BOOST_CHECK(!isDestroyed);
}
BOOST_CHECK(!isDestroyed);
RCULock::synchronize();
BOOST_CHECK(isDestroyed);
// Acquire/release workflow.
isDestroyed = false;
auto ptr = new RCURefMoveTestItem([&] { isDestroyed = true; });
auto ptrCopy = ptr;
BOOST_CHECK_THROW(RCUPtr<RCURefMoveTestItem>::copy(ptr),
std::runtime_error);
rcuptr1 = RCUPtr<RCURefMoveTestItem>::acquire(ptr);
BOOST_CHECK_EQUAL(rcuptr1, ptrCopy);
BOOST_CHECK_EQUAL(ptr, NULLPTR(RCURefMoveTestItem));
ptr = rcuptr1.release();
BOOST_CHECK_EQUAL(rcuptr1, NULLPTR(RCURefMoveTestItem));
BOOST_CHECK_EQUAL(ptr, ptrCopy);
RCULock::synchronize();
BOOST_CHECK(!isDestroyed);
RCUPtr<RCURefMoveTestItem>::acquire(ptr);
BOOST_CHECK_EQUAL(ptr, NULLPTR(RCURefMoveTestItem));
BOOST_CHECK(!isDestroyed);
RCULock::synchronize();
BOOST_CHECK(isDestroyed);
}
BOOST_AUTO_TEST_SUITE_END()

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