ams-tschoening commented on a change in pull request #68:
URL: https://github.com/apache/logging-log4cxx/pull/68#discussion_r695481684
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File path: src/main/include/log4cxx/helpers/threadutility.h
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@@ -0,0 +1,119 @@
+#ifndef _LOG4CXX_THREADUTILITY_H
+#define _LOG4CXX_THREADUTILITY_H
+
+#include <thread>
+#include <functional>
+#include <memory>
+
+#include "log4cxx/logstring.h"
+
+namespace log4cxx {
+namespace helpers {
+
+/**
+ * A function that will be called before a thread is started. This can
+ * be used to (for example) block all of the signals in the thread, so
+ * that when the thread is created it will have a correct signal mask.
+ */
+typedef std::function<void()> pre_thread_start;
+
+/**
+ * Called when a new thread has started. This can be used to set
+ * parameters for the thread in a platform-specific manner.
+ *
+ * @param threadName The name of the thread
+ * @param thread_id The ID of the thread as reported by std::thread::get_id
+ * @param native_handle The native handle of the thread, as reported by
+ * std::thread::native_handle
+ */
+typedef std::function<void( LogString threadName,
+ std::thread::id thread_id,
+ std::thread::native_handle_type native_handle
)> thread_started;
+
+/**
+ * Called after a thread has started. This can be used to (for example)
+ * unblock the signals in the thread.
+ */
+typedef std::function<void()> post_thread_start;
+
+class ThreadUtility;
+LOG4CXX_PTR_DEF(ThreadUtility);
+
+class LOG4CXX_EXPORT ThreadUtility {
+private:
+ ThreadUtility();
+
+ log4cxx::helpers::pre_thread_start preStartFunction();
+ log4cxx::helpers::thread_started threadStartedFunction();
+ log4cxx::helpers::post_thread_start postStartFunction();
+
+ struct priv_data;
+ std::unique_ptr<priv_data> m_priv;
+
+public:
+ ~ThreadUtility();
+
+ static std::shared_ptr<ThreadUtility> instance();
+
+ /**
+ * Configure the thread functions that log4cxx will use.
+ * Note that setting any of these parameters to nullptr is valid,
+ * and simply results in the callback not being called. *
+ */
+ void configureThreadFunctions( pre_thread_start pre_start,
+
thread_started started,
+
post_thread_start post_start );
+
+ /**
+ * A pre-start thread function that blocks signals to the new thread
+ * (if the system has pthreads). If the system does not have pthreads,
+ * is equivalent to preThreadDoNothing();
+ */
+ void preThreadBlockSignals();
+
+ /**
+ * A thread_started function that names the thread using the appropriate
+ * system call.
+ */
+ void threadStartedNameThread(LogString threadName,
+
std::thread::id thread_id,
+
std::thread::native_handle_type native_handle);
+
+ /**
+ * A post-start thread function that unblocks signals that
preThreadBlockSignals
+ * blocked before starting the thread. If the system does not have
pthreads,
+ * is equivalent to postThreadDoNothing();
+ */
+ void postThreadUnblockSignals();
+
+ /**
+ * Start a thread
+ */
+ template<class Function, class... Args>
+ std::thread createThread(LogString name,
+ Function&& f,
+ Args&&... args){
+ log4cxx::helpers::pre_thread_start pre_start =
preStartFunction();
+ log4cxx::helpers::thread_started thread_start =
threadStartedFunction();
+ log4cxx::helpers::post_thread_start post_start =
postStartFunction();
+
+ if( pre_start ){
+ pre_start();
+ }
+ std::thread t( f, args... );
+ if( thread_start ){
+ thread_start( name,
+ t.get_id(),
+ t.native_handle() );
+ }
+ if( post_start ){
Review comment:
> I agree they could be merged into one; I wasn't sure if it made sense
to split them apart. They do technically get called at effectively the same
time.[...]
Their purpose/focus/... might still be different: `pre` and `post` focus on
preparing/resetting the environment for/after new threads, the other callback
focuses on configuring/... the created thread itself. Doesn't sound too wrong
to me, I'm fine with keeping things that way.
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