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C++ Boost

Boost.Threads

Header <boost/thread/tss.hpp>


Contents

Introduction
Classes
Class thread_specific_ptr
Class thread_specific_ptr synopsis
Class thread_specific_ptr constructors and destructor
Class thread_specific_ptr modifier functions
Class thread_specific_ptr observer functions
Example(s)

Introduction

The header <boost/thread/tss.hpp> defines the class thread_specific_ptr which is used to manage data associated with specific thread instances.

Classes

Class thread_specific_ptr

The thread_specific_ptr class defines an interface for using thread specific storage. Thread specific storage is data associated with individual threads and is often used to make operations thread-safe that rely on global data.

Template thread_specific_ptr stores a pointer to an object obtained via new on a thread-by-thread basis and calls delete on the contained pointer when the thread terminates. Each thread initially stores the null pointer in each thread_specific_ptr instance.

The template thread_specific_ptr is useful in the following cases:

Class thread_specific_ptr synopsis

namespace boost
{
    template <typename T>
    class thread_specific_ptr : private boost::noncopyable // Exposition only.
        // Class thread_specific_ptr meets the NonCopyable requirement.
    {
    public:
        thread_specific_ptr();
        ~thread_specific_ptr();

        T* get() const;
        T* operator->() const;
        T& operator*() const;
        T* release();
        void reset(T* p=0);
    };
};

Class thread_specific_ptr constructors and destructor

thread_specific_ptr();
Requires: The expression delete get() is well formed.
Postconditions: A thread specific storage has been reserved for use by *this in all threads, with each thread initially storing a null pointer.
Throws: boost::thread_resource_error if the necessary resources can not be obtained.
Note: There is an implementation specific limit to the number of thread specific storage objects that can be created, and this limit may be small.
~thread_specific_ptr();
Note: Does not destroy any data that may be stored in any thread's thread specific storage. For this reason you should not destroy a thread_specific_ptr object until you are certain there are no threads running that have made use of its thread specific storage.

Class thread_specific_ptr modifier functions

T* release();
Postconditions: *this holds the null pointer for the current thread.
Returns: this->get() prior to the call.
void reset(T* p=0);
Effects: If this->get()!= p then delete this->get().
Postconditions: *this holds the pointer p for the current thread.
Note: The pointer will be deleted when the thread terminates.

Class thread_specific_ptr observer functions

T* get() const;
Returns: The object stored in thread specific storage for the current thread for *this.
Note: Each thread initially returns 0.
T* operator->() const;
Returns: this-<get().
T& operator*() const;
Requires: this-<get() != 0
Returns: this-<get().

Example(s)

libs/thread/example/tss.cpp


Revised 05 November, 2001

© Copyright William E. Kempf 2001-2002. All Rights Reserved.

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