thread_safe_init. NXP CodeWarrior Development Studio

Chapter 29 Pragmas for C++

template too complex or recursive

This pragma does not correspond to any panel setting.

29.42 thread_safe_init

Controls the addition of extra code in the binary to ensure that multiple threads cannot enter a static local initialization at the same time.

Syntax

#pragma thread_safe_init on | off | reset

Remarks

A C++ program that uses multiple threads and static local initializations introduces the possibility of contention over which thread initializes static local variable first. When the pragma is on

, the compiler inserts calls to mutex functions around each static local initialization to avoid this problem. The C++ runtime library provides these mutex functions.

Listing 29-12. Static local initialization example

int func(void) {

// There may be synchronization problems if this function is

// called by multiple threads.

static int countdown = 20;

return countdown--;

}

NOTE

This pragma requires runtime library functions which may not be implemented on all platforms, due to the possible need for operating system support.

Listing 29-13 on page 453 shows another example.

Listing 29-13. Example thread_safe_init

#pragma thread_safe_init on void thread_heavy_func()

{

// Multiple threads can now safely call this function:

// the static local variable will be constructed only once.

static std::string localstring = thread_unsafe_func();

}

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