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Merge pull request #2446

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6d0ca7d1 Tweak concurrency limits (Howard Chu)
510d0d47 Use a threadpool (Howard Chu)
This commit is contained in:
Riccardo Spagni 2017-09-18 13:19:26 +02:00
commit 1a73843cec
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15 changed files with 306 additions and 963 deletions
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6
src/common/CMakeLists.txt
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@ -37,8 +37,7 @@ set(common_sources
i18n.cpp
password.cpp
perf_timer.cpp
task_region.cpp
thread_group.cpp
threadpool.cpp
updates.cpp)
if (STACK_TRACE)
@ -66,8 +65,7 @@ set(common_private_headers
password.h
perf_timer.h
stack_trace.h
task_region.h
thread_group.h
threadpool.h
updates.h)
monero_private_headers(common

3
src/common/common_fwd.h
View file

@ -36,6 +36,5 @@ namespace tools
struct login;
class password_container;
class t_http_connection;
class task_region;
class thread_group;
class threadpool;
}

94
src/common/task_region.cpp
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@ -1,94 +0,0 @@
// Copyright (c) 2014-2017, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "common/task_region.h"
#include <boost/thread/locks.hpp>
#include <cassert>
/* `mark_completed` and `wait` can throw in the lock call, but its difficult to
recover from either. An exception in `wait` means the post condition of joining
all threads cannot be achieved, and an exception in `mark_completed` means
certain deadlock. `noexcept` qualifier will force a call to `std::terminate` if
locking throws an exception, which should only happen if a recursive lock
attempt is made (which is not possible since no external function is called
while holding the lock). */
namespace tools
{
void task_region_handle::state::mark_completed(id task_id) noexcept {
assert(task_id != 0 && (task_id & (task_id - 1)) == 0); // power of 2 check
if (pending.fetch_and(~task_id) == task_id) {
// synchronize with wait call, but do not need to hold
boost::unique_lock<boost::mutex>{sync_on_complete};
all_complete.notify_all();
}
}
void task_region_handle::state::abort() noexcept {
state* current = this;
while (current) {
current->ready = 0;
current = current->next.get();
}
}
void task_region_handle::state::wait() noexcept {
state* current = this;
while (current) {
{
boost::unique_lock<boost::mutex> lock{current->sync_on_complete};
current->all_complete.wait(lock, [current] { return current->pending == 0; });
}
current = current->next.get();
}
}
void task_region_handle::state::wait(thread_group& threads) noexcept {
state* current = this;
while (current) {
while (current->pending != 0) {
if (!threads.try_run_one()) {
current->wait();
return;
}
}
current = current->next.get();
}
}
void task_region_handle::create_state() {
st = std::make_shared<state>(std::move(st));
next_id = 1;
}
void task_region_handle::do_wait() noexcept {
assert(st);
const std::shared_ptr<state> temp = std::move(st);
temp->wait(threads);
}
}

223
src/common/task_region.h
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@ -1,223 +0,0 @@
// Copyright (c) 2014-2017, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#pragma once
#include <atomic>
#include <boost/thread/condition_variable.hpp>
#include <boost/thread/mutex.hpp>
#include <memory>
#include <type_traits>
#include <utility>
#include "common/thread_group.h"
namespace tools
{
/*! A model of the fork-join concept. `run(...)` "forks" (i.e. spawns new
tasks), and `~task_region_handle()` or `wait()` "joins" the spawned tasks.
`wait` will block until all tasks have completed, while `~task_region_handle()`
blocks until all tasks have completed or aborted.
Do _NOT_ give this object to separate thread of execution (which includes
`task_region_handle::run(...)`) because joining on a different thread is
undesireable (potential deadlock).
This class cannot be constructed directly, use the function
`task_region(...)` instead.
*/
class task_region_handle
{
struct state
{
using id = unsigned;
explicit state(std::shared_ptr<state> next_src) noexcept
: next(std::move(next_src))
, ready(0)
, pending(0)
, sync_on_complete()
, all_complete() {
}
state(const state&) = default;
state(state&&) = default;
~state() = default;
state& operator=(const state&) = default;
state& operator=(state&&) = default;
void track_id(id task_id) noexcept {
pending |= task_id;
ready |= task_id;
}
//! \return True only once whether a given id can execute
bool can_run(id task_id) noexcept {
return (ready.fetch_and(~task_id) & task_id);
}
//! Mark id as completed, and synchronize with waiting threads
void mark_completed(id task_id) noexcept;
//! Tell all unstarted functions in region to return immediately
void abort() noexcept;
//! Blocks until all functions in region have aborted or completed.
void wait() noexcept;
//! Same as `wait()`, except `this_thread` runs tasks while waiting.
void wait(thread_group& threads) noexcept;
private:
/* This implementation is a bit pessimistic, it ensures that all copies
of a wrapped task can only be executed once. `thread_group` should never
do this, but some variable needs to track whether an abort should be done
anyway... */
std::shared_ptr<state> next;
std::atomic<id> ready; //!< Tracks whether a task has been invoked
std::atomic<id> pending; //!< Tracks when a task has completed or aborted
boost::mutex sync_on_complete;
boost::condition_variable all_complete;
};
template<typename F>
struct wrapper
{
wrapper(state::id id_src, std::shared_ptr<state> st_src, F f_src)
: task_id(id_src), st(std::move(st_src)), f(std::move(f_src)) {
}
wrapper(const wrapper&) = default;
wrapper(wrapper&&) = default;
wrapper& operator=(const wrapper&) = default;
wrapper& operator=(wrapper&&) = default;
void operator()() {
if (st) {
if (st->can_run(task_id)) {
f();
}
st->mark_completed(task_id);
}
}
private:
const state::id task_id;
std::shared_ptr<state> st;
F f;
};
public:
friend struct task_region_;
task_region_handle() = delete;
task_region_handle(const task_region_handle&) = delete;
task_region_handle(task_region_handle&&) = delete;
//! Cancels unstarted pending tasks, and waits for them to respond.
~task_region_handle() noexcept {
if (st) {
st->abort();
st->wait(threads);
}
}
task_region_handle& operator=(const task_region_handle&) = delete;
task_region_handle& operator=(task_region_handle&&) = delete;
/*! If the group has no threads, `f` is immediately run before returning.
Otherwise, `f` is dispatched to the thread_group associated with `this`
region. If `f` is dispatched to another thread, and it throws, the process
will immediately terminate. See std::packaged_task for getting exceptions on
functions executed on other threads. */
template<typename F>
void run(F&& f) {
if (threads.count() == 0) {
f();
} else {
if (!st || next_id == 0) {
create_state();
}
const state::id this_id = next_id;
next_id <<= 1;
st->track_id(this_id);
threads.dispatch(wrapper<F>{this_id, st, std::move(f)});
}
}
//! Wait until all functions provided to `run` have completed.
void wait() noexcept {
if (st) {
do_wait();
}
}
private:
explicit task_region_handle(thread_group& threads_src)
: st(nullptr), threads(threads_src), next_id(0) {
}
void create_state();
void do_wait() noexcept;
std::shared_ptr<state> st;
thread_group& threads;
state::id next_id;
};
/*! Function for creating a `task_region_handle`, which automatically calls
`task_region_handle::wait()` before returning. If a `thread_group` is not
provided, one is created with an optimal number of threads. The callback `f`
must have the signature `void(task_region_handle&)`. */
struct task_region_ {
template<typename F>
void operator()(thread_group& threads, F&& f) const {
static_assert(
std::is_same<void, typename std::result_of<F(task_region_handle&)>::type>::value,
"f cannot have a return value"
);
task_region_handle region{threads};
f(region);
region.wait();
}
template<typename F>
void operator()(thread_group&& threads, F&& f) const {
(*this)(threads, std::forward<F>(f));
}
template<typename F>
void operator()(F&& f) const {
thread_group threads;
(*this)(threads, std::forward<F>(f));
}
};
constexpr const task_region_ task_region{};
}

153
src/common/thread_group.cpp
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@ -1,153 +0,0 @@
// Copyright (c) 2014-2017, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "common/thread_group.h"
#include <boost/thread/locks.hpp>
#include <cassert>
#include <limits>
#include <stdexcept>
#include "cryptonote_config.h"
#include "common/util.h"
namespace tools
{
std::size_t thread_group::optimal() {
static_assert(
std::numeric_limits<unsigned>::max() <= std::numeric_limits<std::size_t>::max(),
"unexpected truncation"
);
const std::size_t hardware = get_max_concurrency();
return hardware ? (hardware - 1) : 0;
}
std::size_t thread_group::optimal_with_max(std::size_t count) {
return count ? std::min(count - 1, optimal()) : 0;
}
thread_group::thread_group(std::size_t count) : internal() {
if (count) {
internal.emplace(count);
}
}
thread_group::data::data(std::size_t count)
: threads()
, head{nullptr}
, last(std::addressof(head))
, mutex()
, has_work()
, stop(false) {
threads.reserve(count);
boost::thread::attributes attrs;
attrs.set_stack_size(THREAD_STACK_SIZE);
while (count--) {
threads.push_back(boost::thread(attrs, boost::bind(&thread_group::data::run, this)));
}
}
thread_group::data::~data() noexcept {
{
const boost::unique_lock<boost::mutex> lock(mutex);
stop = true;
}
has_work.notify_all();
for (auto& worker : threads) {
try {
worker.join();
}
catch(...) {}
}
}
std::unique_ptr<thread_group::data::work> thread_group::data::get_next() noexcept {
std::unique_ptr<work> rc = std::move(head.ptr);
if (rc != nullptr) {
head.ptr = std::move(rc->next.ptr);
if (head.ptr == nullptr) {
last = std::addressof(head);
}
}
return rc;
}
bool thread_group::data::try_run_one() noexcept {
/* This function and `run()` can both throw when acquiring the lock, or in
dispatched function. It is tough to recover from either, particularly the
lock case. These functions are marked as noexcept so that if either call
throws, the entire process is terminated. Users of the `dispatch` call are
expected to make their functions noexcept, or use std::packaged_task to copy
exceptions so that the process will continue in all but the most pessimistic
cases (std::bad_alloc). This was the existing behavior;
`asio::io_service::run` propogates errors from dispatched calls, and uncaught
exceptions on threads result in process termination. */
std::unique_ptr<work> next = nullptr;
{
const boost::unique_lock<boost::mutex> lock(mutex);
next = get_next();
}
if (next) {
assert(next->f);
next->f();
return true;
}
return false;
}
void thread_group::data::run() noexcept {
// see `try_run_one()` source for additional information
while (true) {
std::unique_ptr<work> next = nullptr;
{
boost::unique_lock<boost::mutex> lock(mutex);
has_work.wait(lock, [this] { return head.ptr != nullptr || stop; });
if (stop) {
return;
}
next = get_next();
}
assert(next != nullptr);
assert(next->f);
next->f();
}
}
void thread_group::data::dispatch(std::function<void()> f) {
std::unique_ptr<work> latest(new work{std::move(f), node{nullptr}});
node* const latest_node = std::addressof(latest->next);
{
const boost::unique_lock<boost::mutex> lock(mutex);
assert(last != nullptr);
assert(last->ptr == nullptr);
last->ptr = std::move(latest);
last = latest_node;
}
has_work.notify_one();
}
}

143
src/common/thread_group.h
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@ -1,143 +0,0 @@
// Copyright (c) 2014-2017, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#pragma once
#include <boost/optional/optional.hpp>
#include <boost/thread/condition_variable.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/thread/thread.hpp>
#include <cstddef>
#include <functional>
#include <thread>
#include <utility>
#include <vector>
namespace tools
{
//! Manages zero or more threads for work dispatching.
class thread_group
{
public:
//! \return `get_max_concurrency() ? get_max_concurrency() - 1 : 0`
static std::size_t optimal();
//! \return `count ? min(count - 1, optimal()) : 0`
static std::size_t optimal_with_max(std::size_t count);
//! Create an optimal number of threads.
explicit thread_group() : thread_group(optimal()) {}
//! Create exactly `count` threads.
explicit thread_group(std::size_t count);
thread_group(thread_group const&) = delete;
thread_group(thread_group&&) = delete;
//! Joins threads, but does not necessarily run all dispatched functions.
~thread_group() = default;
thread_group& operator=(thread_group const&) = delete;
thread_group& operator=(thread_group&&) = delete;
//! \return Number of threads owned by `this` group.
std::size_t count() const noexcept {
if (internal) {
return internal->count();
}
return 0;
}
//! \return True iff a function was available and executed (on `this_thread`).
bool try_run_one() noexcept {
if (internal) {
return internal->try_run_one();
}
return false;
}
/*! `f` is invoked immediately if `count() == 0`, otherwise execution of `f`
is queued for next available thread. If `f` is queued, any exception leaving
that function will result in process termination. Use std::packaged_task if
exceptions need to be handled. */
template<typename F>
void dispatch(F&& f) {
if (internal) {
internal->dispatch(std::forward<F>(f));
}
else {
f();
}
}
private:
class data {
public:
data(std::size_t count);
~data() noexcept;
std::size_t count() const noexcept {
return threads.size();
}
bool try_run_one() noexcept;
void dispatch(std::function<void()> f);
private:
struct work;
struct node {
std::unique_ptr<work> ptr;
};
struct work {
std::function<void()> f;
node next;
};
//! Requires lock on `mutex`.
std::unique_ptr<work> get_next() noexcept;
//! Blocks until destructor is invoked, only call from thread.
void run() noexcept;
private:
std::vector<boost::thread> threads;
node head;
node* last;
boost::condition_variable has_work;
boost::mutex mutex;
bool stop;
};
private:
// optionally construct elements, without separate heap allocation
boost::optional<data> internal;
};
}

117
src/common/threadpool.cpp Normal file
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@ -0,0 +1,117 @@
// Copyright (c) 2017, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "common/threadpool.h"
#include <cassert>
#include <limits>
#include <stdexcept>
#include "cryptonote_config.h"
#include "common/util.h"
namespace tools
{
threadpool::threadpool() : running(true), active(0) {
boost::thread::attributes attrs;
attrs.set_stack_size(THREAD_STACK_SIZE);
max = tools::get_max_concurrency() * 2;
size_t i = max;
while(i--) {
threads.push_back(boost::thread(attrs, boost::bind(&threadpool::run, this)));
}
}
threadpool::~threadpool() {
{
const boost::unique_lock<boost::mutex> lock(mutex);
running = false;
has_work.notify_all();
}
for (size_t i = 0; i<threads.size(); i++) {
threads[i].join();
}
}
void threadpool::submit(waiter *obj, std::function<void()> f) {
entry e = {obj, f};
boost::unique_lock<boost::mutex> lock(mutex);
if (active == max && !queue.empty()) {
// if all available threads are already running
// and there's work waiting, just run in current thread
lock.unlock();
f();
} else {
if (obj)
obj->inc();
queue.push_back(e);
has_work.notify_one();
}
}
int threadpool::get_max_concurrency() {
return max / 2;
}
void threadpool::waiter::wait() {
boost::unique_lock<boost::mutex> lock(mt);
while(num) cv.wait(lock);
}
void threadpool::waiter::inc() {
const boost::unique_lock<boost::mutex> lock(mt);
num++;
}
void threadpool::waiter::dec() {
const boost::unique_lock<boost::mutex> lock(mt);
num--;
if (!num)
cv.notify_one();
}
void threadpool::run() {
boost::unique_lock<boost::mutex> lock(mutex);
while (running) {
entry e;
while(queue.empty() && running)
has_work.wait(lock);
if (!running) break;
active++;
e = queue.front();
queue.pop_front();
lock.unlock();
e.f();
if (e.wo)
e.wo->dec();
lock.lock();
active--;
}
}
}

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@ -0,0 +1,87 @@
// Copyright (c) 2017, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#pragma once
#include <boost/thread/condition_variable.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/thread/thread.hpp>
#include <cstddef>
#include <functional>
#include <utility>
#include <vector>
namespace tools
{
//! A global thread pool
class threadpool
{
public:
static threadpool& getInstance() {
static threadpool instance;
return instance;
}
// The waiter lets the caller know when all of its
// tasks are completed.
class waiter {
boost::mutex mt;
boost::condition_variable cv;
int num;
public:
void inc();
void dec();
void wait(); //! Wait for a set of tasks to finish.
waiter() : num(0){}
~waiter() { wait(); }
};
// Submit a task to the pool. The waiter pointer may be
// NULL if the caller doesn't care to wait for the
// task to finish.
void submit(waiter *waiter, std::function<void()> f);
int get_max_concurrency();
private:
threadpool();
~threadpool();
typedef struct entry {
waiter *wo;
std::function<void()> f;
} entry;
std::deque<entry> queue;
boost::condition_variable has_work;
boost::mutex mutex;
std::vector<boost::thread> threads;
int active;
int max;
bool running;
void run();
};
}