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/* SPDX-License-Identifier: BSD-3-Clause
* Copyright(c) 2015 Intel Corporation
*/
#ifndef _PTHREAD_SHIM_H_
#define _PTHREAD_SHIM_H_
#include <rte_lcore.h>
/*
* This pthread shim is an example that demonstrates how legacy code
* that makes use of POSIX pthread services can make use of lthreads
* with reduced porting effort.
*
* N.B. The example is not a complete implementation, only a subset of
* pthread APIs sufficient to demonstrate the principle of operation
* are implemented.
*
* In general pthread attribute objects do not have equivalent functions
* in lthreads, and are ignored.
*
* There is one exception and that is the use of attr to specify a
* core affinity in calls to pthread_create.
*
* The shim operates as follows:-
*
* On initialisation a constructor function uses dlsym to obtain and
* save the loaded address of the full set of pthread APIs that will
* be overridden.
*
* For each function there is a stub provided that will invoke either
* the genuine pthread library function saved saved by the constructor,
* or else the corresponding equivalent lthread function.
*
* The stub functions are implemented in pthread_shim.c
*
* The stub will take care of adapting parameters, and any police
* any constraints where lthread functionality differs.
*
* The initial thread must always be a pure lthread.
*
* The decision whether to invoke the real library function or the lthread
* function is controlled by a per pthread flag that can be switched
* on of off by the pthread_override_set() API described below. Typcially
* this should be done as the first action of the initial lthread.
*
* N.B In general it would be poor practice to revert to invoke a real
* pthread function when running as an lthread, since these may block and
* effectively stall the lthread scheduler.
*
*/
/*
* An exiting lthread must not terminate the pthread it is running in
* since this would mean terminating the lthread scheduler.
* We override pthread_exit() with a macro because it is typically declared with
* __attribute__((noreturn))
*/
void pthread_exit_override(void *v);
#define pthread_exit(v) do { \
pthread_exit_override((v)); \
return NULL; \
} while (0)
/*
* Enable/Disable pthread override
* state
* 0 disable
* 1 enable
*/
void pthread_override_set(int state);
/*
* Return pthread override state
* return
* 0 disable
* 1 enable
*/
int pthread_override_get(void);
#endif /* _PTHREAD_SHIM_H_ */
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