Multi Threading Manager. More...

#include <multi_threading_mgr.h>

Inheritance diagram for isc::util::MultiThreadingMgr:

Public Member Functions
void	addCriticalSectionCallbacks (const std::string &name, const CSCallbackPair::Callback &entry_cb, const CSCallbackPair::Callback &exit_cb)
	Adds a pair of callbacks to the list of CriticalSection callbacks. More...

void	apply (bool enabled, uint32_t thread_count, uint32_t queue_size)
	Apply the multi-threading related settings. More...

void	enterCriticalSection ()
	Enter critical section. More...

void	exitCriticalSection ()
	Exit critical section. More...

bool	getMode () const
	Get the multi-threading mode. More...

uint32_t	getPacketQueueSize ()
	Get the configured dhcp packet queue size. More...

ThreadPool< std::function< void()> > &	getThreadPool ()
	Get the dhcp thread pool. More...

uint32_t	getThreadPoolSize () const
	Get the configured dhcp thread pool size. More...

bool	isInCriticalSection ()
	Is in critical section flag. More...

void	removeAllCriticalSectionCallbacks ()
	Removes all callbacks in the list of CriticalSection callbacks. More...

void	removeCriticalSectionCallbacks (const std::string &name)
	Removes the set of callbacks associated with a given name from the list of CriticalSection callbacks. More...

void	setMode (bool enabled)
	Set the multi-threading mode. More...

void	setPacketQueueSize (uint32_t size)
	Set the configured dhcp packet queue size. More...

void	setThreadPoolSize (uint32_t size)
	Set the configured dhcp thread pool size. More...

Static Public Member Functions
static uint32_t	detectThreadCount ()
	The system current detected hardware concurrency thread count. More...

static MultiThreadingMgr &	instance ()
	Returns a single instance of Multi Threading Manager. More...

Protected Member Functions
	MultiThreadingMgr ()
	Constructor. More...

virtual	~MultiThreadingMgr ()
	Destructor. More...

Detailed Description

Multi Threading Manager.

This singleton class holds the multi-threading mode.

The standard way to use it is:

if (MultiThreadingMgr::instance().getMode()) {
    multi-threaded code
} else {
    single-threaded code
}

For instance for a class protected by its mutex:

namespace locked {
    void foo() { ... }
} // end of locked namespace
void foo() {
    if (MultiThreadingMgr::instance().getMode()) {
        lock_guard<mutex> lock(mutex_);
        locked::foo();
    } else {
        locked::foo();
    }
}

Definition at line 120 of file multi_threading_mgr.h.

Constructor & Destructor Documentation

isc::util::MultiThreadingMgr::MultiThreadingMgr ( )

protected

Constructor.

Definition at line 14 of file multi_threading_mgr.cc.

isc::util::MultiThreadingMgr::~MultiThreadingMgr ( )

protectedvirtual

Destructor.

Definition at line 18 of file multi_threading_mgr.cc.

Member Function Documentation

void isc::util::MultiThreadingMgr::addCriticalSectionCallbacks	(	const std::string &	name,
		const CSCallbackPair::Callback &	entry_cb,
		const CSCallbackPair::Callback &	exit_cb
	)

Adds a pair of callbacks to the list of CriticalSection callbacks.

Note: Callbacks must be exception-safe, handling any errors themselves.

Parameters

name	Name of the set of callbacks. This value is used by the callback owner to add and remove them. Duplicates are not allowed.
entry_cb	Callback to invoke upon CriticalSection entry. Cannot be empty.
exit_cb	Callback to invoke upon CriticalSection exit. Cannot be empty.

Definition at line 160 of file multi_threading_mgr.cc.

References isc::util::CSCallbackPairList::addCallbackPair().

Here is the call graph for this function:

void isc::util::MultiThreadingMgr::apply	(	bool	enabled,
		uint32_t	thread_count,
		uint32_t	queue_size
	)

Apply the multi-threading related settings.

Parameters

enabled	The enabled flag: true if multi-threading is enabled, false otherwise.
thread_count	The desired number of threads: non 0 if explicitly configured, 0 if auto scaling is desired
queue_size	The desired thread queue size: non 0 if explicitly configured, 0 for unlimited size

Definition at line 88 of file multi_threading_mgr.cc.

References detectThreadCount(), isInCriticalSection(), removeAllCriticalSectionCallbacks(), isc::util::ThreadPool< WorkItem, Container >::reset(), setMode(), setPacketQueueSize(), setThreadPoolSize(), isc::util::ThreadPool< WorkItem, Container >::size(), isc::util::ThreadPool< WorkItem, Container >::start(), and isc::util::ThreadPool< WorkItem, Container >::stop().

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uint32_t isc::util::MultiThreadingMgr::detectThreadCount ( )

static

The system current detected hardware concurrency thread count.

This function will return 0 if the value can not be determined.

Returns: The thread count.

Definition at line 83 of file multi_threading_mgr.cc.

Referenced by apply().

void isc::util::MultiThreadingMgr::enterCriticalSection ( )

Enter critical section.

When entering MultiThreadingCriticalSection, increment internal counter so that any configuration change that might start the packet thread pool is delayed until exiting the respective section. If the internal counter is 0, then stop the thread pool.

Definition at line 38 of file multi_threading_mgr.cc.

Referenced by isc::util::MultiThreadingCriticalSection::MultiThreadingCriticalSection().

void isc::util::MultiThreadingMgr::exitCriticalSection ( )

Exit critical section.

When exiting MultiThreadingCriticalSection, decrement internal counter so that the dhcp thread pool can be started according to the new configuration. If the internal counter is 0, then start the thread pool.

Definition at line 44 of file multi_threading_mgr.cc.

References isc_throw.

Referenced by isc::util::MultiThreadingCriticalSection::~MultiThreadingCriticalSection().

bool isc::util::MultiThreadingMgr::getMode ( ) const

Get the multi-threading mode.