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Merged
vinniefalco merged 2 commits into from
Jan 20, 2026
+51 −74
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thread_pool improvements: jthread, stop, lazy #86

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thread_pool improvements: jthread, stop, lazy
vinniefalco Jan 20, 2026
f125ed0
tests Jamfile uses glob
vinniefalco Jan 20, 2026
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9 changes: 9 additions & 0 deletions include/boost/capy/ex/thread_pool.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,15 @@ class BOOST_CAPY_DECL
thread_pool(thread_pool const&) = delete;
thread_pool& operator=(thread_pool const&) = delete;

/** Request all worker threads to stop.

Signals all threads to exit via stop token. Threads will
finish their current work item before exiting. Does not
wait for threads to exit.
*/
void
stop() noexcept;

/** Return an executor for this thread pool.

@return An executor associated with this thread pool.
Expand Down
77 changes: 41 additions & 36 deletions src/ex/thread_pool.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
#include <boost/capy/core/intrusive_queue.hpp>
#include <condition_variable>
#include <mutex>
#include <stop_token>
#include <thread>
#include <vector>

Expand All @@ -19,10 +20,8 @@ namespace capy {

//------------------------------------------------------------------------------

// Pimpl implementation hides threading details from the header
class thread_pool::impl
{
// Wraps a coroutine handle for queue storage
struct work : intrusive_queue<work>::node
{
any_coro h_;
Expand All @@ -34,7 +33,6 @@ class thread_pool::impl

void run()
{
// delete before dispatch
auto h = h_;
delete this;
h.resume();
Expand All @@ -47,46 +45,36 @@ class thread_pool::impl
};

std::mutex mutex_;
std::condition_variable cv_;
std::condition_variable_any cv_;
intrusive_queue<work> q_;
std::vector<std::thread> threads_;
bool stop_;
std::vector<std::jthread> threads_;
std::size_t num_threads_;
std::once_flag start_flag_;

public:
~impl()
{
{
std::lock_guard<std::mutex> lock(mutex_);
stop_ = true;
}
cv_.notify_all();

for(auto& t : threads_)
t.join();
stop();
threads_.clear();

// Destroy any work items that were never executed
while(auto* w = q_.pop())
w->destroy();
}

explicit
impl(std::size_t num_threads)
: stop_(false)
: num_threads_(num_threads)
{
if( num_threads == 0)
num_threads = std::thread::hardware_concurrency();
// Fallback
if( num_threads == 0)
num_threads = 1;

threads_.reserve(num_threads);
for(std::size_t i = 0; i < num_threads; ++i)
threads_.emplace_back([this]{ run(); });
if(num_threads_ == 0)
num_threads_ = std::thread::hardware_concurrency();
if(num_threads_ == 0)
num_threads_ = 1;
}

void
post(any_coro h)
{
ensure_started();
auto* w = new work(h);
{
std::lock_guard<std::mutex> lock(mutex_);
Expand All @@ -95,26 +83,37 @@ class thread_pool::impl
cv_.notify_one();
}

void
stop() noexcept
{
for (auto& t : threads_)
t.request_stop();
cv_.notify_all();
}

private:
void
run()
ensure_started()
{
std::call_once(start_flag_, [this]{
threads_.reserve(num_threads_);
for(std::size_t i = 0; i < num_threads_; ++i)
threads_.emplace_back([this](std::stop_token st){ run(st); });
});
}

void
run(std::stop_token st)
{
for(;;)
{
work* w = nullptr;
{
std::unique_lock<std::mutex> lock(mutex_);
cv_.wait(lock, [this]{
return stop_ || !q_.empty();
});

// Only exit when stopped AND queue is drained
if(stop_ && q_.empty())
if(!cv_.wait(lock, st, [this]{ return !q_.empty(); }))
return;

w = q_.pop();
}

w->run();
}
}
Expand All @@ -125,10 +124,9 @@ class thread_pool::impl
thread_pool::
~thread_pool()
{
// Order matters: shutdown services, then impl, then base
shutdown();
delete impl_;
destroy();
delete impl_;
}

thread_pool::
Expand All @@ -137,6 +135,13 @@ thread_pool(std::size_t num_threads)
{
}

void
thread_pool::
stop() noexcept
{
impl_->stop();
}

//------------------------------------------------------------------------------

void
Expand Down
5 changes: 1 addition & 4 deletions test/unit/Jamfile
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Expand Up @@ -26,8 +26,7 @@ project
<target-os>darwin,<undefined-sanitizer>norecover:<link>static
;

# Exclude buffers/ which has its own Jamfile
for local f in [ glob-tree-ex . : *.cpp : file*.cpp buffers ]
for local f in [ glob-tree-ex . : *.cpp : file*.cpp ]
{
run $(f) ;
}
Comment on lines +29 to 32
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⚠️ Potential issue | 🔴 Critical

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# Search for any remaining buffers-specific configuration in Jamfiles
rg -n --glob 'Jamfile*' -C2 'buffers'

Repository: cppalliance/capy

Length of output: 42

🏁 Script executed:

#!/bin/bash
# Check the current structure of test/unit directory
fd --type f 'Jamfile*' test/unit | head -20

Repository: cppalliance/capy

Length of output: 77

🏁 Script executed:

#!/bin/bash
# Get the content of test/unit/Jamfile to see the full context
cat test/unit/Jamfile

Repository: cppalliance/capy

Length of output: 1274

🏁 Script executed:

#!/bin/bash
# Check for any buffers subdirectory and its contents
fd --type f '\.(cpp|h)$' test/unit/buffers 2>/dev/null | head -20

Repository: cppalliance/capy

Length of output: 694

🏁 Script executed:

#!/bin/bash
# List all subdirectories in test/unit to see the current structure
fd --type d . test/unit | head -20

Repository: cppalliance/capy

Length of output: 195

🏁 Script executed:

#!/bin/bash
# Check git history for buffers/Jamfile
git log --oneline --all -- 'test/unit/buffers/Jamfile' 2>/dev/null | head -10

Repository: cppalliance/capy

Length of output: 188

🏁 Script executed:

#!/bin/bash
# Search for any comments or notes about buffers consolidation
rg -n 'buffers' test/unit/Jamfile

Repository: cppalliance/capy

Length of output: 42

🏁 Script executed:

#!/bin/bash
# Check if there are any special dependencies or requirements mentioned in buffers test files
rg -l 'boost/filesystem|requirements' test/unit/buffers/*.cpp | head -5

Repository: cppalliance/capy

Length of output: 42

🏁 Script executed:

#!/bin/bash
# Check the commits that touched buffers/Jamfile to see what was there
git show a915f4d:test/unit/buffers/Jamfile 2>/dev/null || echo "File not in that commit"
git show 3e0ebab:test/unit/buffers/Jamfile 2>/dev/null || echo "File not in that commit"

Repository: cppalliance/capy

Length of output: 1994

🏁 Script executed:

#!/bin/bash
# Check if buffers/Jamfile still exists
ls -la test/unit/buffers/Jamfile 2>/dev/null || echo "Jamfile does not exist in buffers"

Repository: cppalliance/capy

Length of output: 93

🏁 Script executed:

#!/bin/bash
# Check the diff of the commit that may have removed it
git show --stat a915f4d | grep -i jamfile

Repository: cppalliance/capy

Length of output: 242

🏁 Script executed:

#!/bin/bash
# Check if buffers tests include ASIO headers
rg 'boost/asio|boost.asio' test/unit/buffers/ 2>/dev/null | head -10

Repository: cppalliance/capy

Length of output: 119

🏁 Script executed:

#!/bin/bash
# Check the asio.cpp test specifically
cat test/unit/buffers/asio.cpp

Repository: cppalliance/capy

Length of output: 5304

Add ASIO library dependency for buffers tests.

The consolidation removed the <library>/boost/asio//boost_asio/<warnings-as-errors>off and Windows define (<define>_WIN32_WINNT=0x0601) requirements that were in test/unit/buffers/Jamfile. The asio.cpp test depends on ASIO headers and won't build without this library dependency. Consider adding a separate glob-tree-ex loop for buffers tests (similar to the file*.cpp loop on lines 34-39) with the required ASIO library, or add ASIO to the top-level project requirements.

🤖 Prompt for AI Agents 
In `@test/unit/Jamfile` around lines 29 - 32, The buffers tests lost the ASIO
dependency and required Windows define when the Jamfiles were consolidated;
update the Jamfile by adding a dedicated glob-tree-ex loop for buffers sources
(e.g., match asio.cpp) that invokes run $(f) with the ASIO library stanza
(<library>/boost/asio//boost_asio/<warnings-as-errors>off) and the define
_WIN32_WINNT=0x0601, or alternatively add that ASIO library and define to the
top-level project requirements so the asio.cpp test will find ASIO headers and
build successfully.

Expand All @@ -40,5 +39,3 @@ for local f in [ glob-tree-ex . : file*.cpp ]
<warnings>off <undefined-sanitizer>norecover:<link>static
;
}

build-project buffers ;
34 changes: 0 additions & 34 deletions test/unit/buffers/Jamfile
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0 test/unit/buffers/buffers.cpp → test/unit/buffers/buffers_.cpp
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