resource_blocker::Resource Class Reference

Represents a "Resource" which can be either "used" by a number of threads, or "blocked" by a number of threads. More...

#include <resource_blocker.h>

Public Types
using	String_set = std::set< std::string >

Public Member Functions
	Resource ()
	~Resource ()
	Resource (Resource &other)=delete
	Resource (Resource &&other)=delete
Resource &	operator= (Resource const &other)=delete
Resource &	operator= (Resource &&other)=delete

Private Member Functions
int	try_block (const std::string &reason)
	Try to block the resource from being used, for the given reason. More...
void	end_block (const std::string &reason)
	Unblock the resource if try_block was previously called successfully. More...
String_set	try_use ()
	Try to start using the resource. More...
void	end_use ()
	Stop using the resource if try_use was previously called successfully. More...
mysql_mutex_t &	get_lock ()

Private Attributes
String_set	m_block_reasons
int	m_user_count
std::atomic< int >	m_initialized
mysql_mutex_t	m_lock

Friends
class	User
class	Blocker

Detailed Description

Represents a "Resource" which can be either "used" by a number of threads, or "blocked" by a number of threads.

When one or more threads use the resource, no thread can block it. When a one or more threads is blocking the resource, no thread can use it. Each blocker provides a message that explains why the resource is blocked.

The resource is blocked or used by creating instances of the Blocker and User classes.

Resource museum;
 
// If the museum is open, visit it. This may be called by multiple threads.
void visit_museum() {
  User user(museum);
  if (!user) return;
  // walk around the museum
}
 
// If there are no guests in the museum, close it temporarily for
// maintenance.
void close_museum_for_maintenance() {
  Blocker blocker(museum, "Museum is currently closed for maintenance.");
  if (!blocker) return;
  // repair exhibitions
}
 
// If there are no guests in the museum, close it temporarily for
// cleaning.
void close_museum_for_cleaning() {
  Blocker blocker(museum, "Museum is currently closed for cleaning.");
  if (!blocker) return;
  // clean the floors
}

Member Typedef Documentation

String_set

using resource_blocker::Resource::String_set = std::set<std::string>

Constructor & Destructor Documentation

Resource() [1/3]

resource_blocker::Resource::Resource ( )

inline

~Resource()

resource_blocker::Resource::~Resource ( )

inline

Resource() [2/3]

resource_blocker::Resource::Resource ( Resource &  other )

delete

Resource() [3/3]

resource_blocker::Resource::Resource ( Resource &&  other )

delete

Member Function Documentation

end_block()

void resource_blocker::Resource::end_block ( const std::string &  reason )

inlineprivate

Unblock the resource if try_block was previously called successfully.

end_use()

void resource_blocker::Resource::end_use ( )

inlineprivate

Stop using the resource if try_use was previously called successfully.

get_lock()

mysql_mutex_t & resource_blocker::Resource::get_lock ( )

inlineprivate

operator=() [1/2]

Resource & resource_blocker::Resource::operator= ( Resource &&  other )

delete

operator=() [2/2]

Resource & resource_blocker::Resource::operator= ( Resource const &  other )

delete

try_block()

int resource_blocker::Resource::try_block ( const std::string &  reason )

inlineprivate

Try to block the resource from being used, for the given reason.

try_use()

String_set resource_blocker::Resource::try_use ( )

inlineprivate

Try to start using the resource.

Friends And Related Function Documentation

Blocker

friend class Blocker

friend

User

friend class User

friend

Member Data Documentation

m_block_reasons

String_set resource_blocker::Resource::m_block_reasons

private

m_initialized

std::atomic<int> resource_blocker::Resource::m_initialized

private

m_lock

mysql_mutex_t resource_blocker::Resource::m_lock

mutableprivate

m_user_count

int resource_blocker::Resource::m_user_count

private

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The documentation for this class was generated from the following file:

• sql/resource_blocker.h