le_thread.h

    1 /**
    2  * @page c_threading Thread Control API
    3  *
    4  * @subpage le_thread.h "API Reference"
    5  *
    6  * <HR>
    7  *
    8  * Generally, using single-threaded, event-driven programming (registering callbacks to be called
    9  * by an event handling loop running in a single thread) is more efficient than using
   10  * multiple threads. With single-threaded, event driven designs:
   11  *  - there's no CPU time spent switching between threads.
   12  *  - there's only one copy of thread-specific memory objects, like the procedure call stack.
   13  *  - there's no need to use thread synchronization mechanisms, like mutexes, to prevent race
   14  *      conditions between threads.
   15  *
   16  * Sometimes, this style doesn't fit well with a problem being solved,
   17  * so you're forced to implement workarounds that severely complicate
   18  * the software design.  In these cases, it is far better to take advantage of multi-threading
   19  *  to simplify the design, even if it means that the program uses more memory or more
   20  * CPU cycles.  In some cases, the workarounds required to avoid multi-threading will
   21  * cost more memory and/or CPU cycles than using multi-threading would.
   22  *
   23  * But you must <b> be careful </b> with multi-threading. Some of the most tenacious,
   24  * intermittent defects known to humankind have resulted from the misuse of multi-threading.
   25  * Ensure you know what you are doing.
   26  *
   27  * @section threadCreating Creating a Thread
   28  *
   29  * To create a thread,  call @c le_thread_Create().
   30  *
   31  * All threads are @b named for two reasons:
   32  *   -# To make it possible to address them by name.
   33  *   -# For diagnostics.
   34  *
   35  * Threads are created in a suspended state.  In this state, attributes like
   36  * scheduling priority and stack size can use the appropriate "Set" functions.
   37  * All attributes have default values so it is not necessary to set any
   38  * attributes (other than the name and main function address, which are passed into
   39  * le_thread_Create() ).  When all attributes have been set, the thread can be started by calling
   40  * le_thread_Start().
   41  *
   42  * @warning It is assumed that if a thread @e T1 creates another thread @e T2 then @b only thread
   43  *          @e T1 will set the attributes and start thread @e T2.  No other thread should try
   44  *          to set any attributes of @e T2 or try to start it.
   45  *
   46  *
   47  * @section threadTerminating Terminating a Thread
   48  *
   49  * Threads can terminate themselves by:
   50  *  - returning from their main function
   51  *  - calling le_thread_Exit().
   52  *
   53  * Threads can also tell other threads to terminate by "canceling" them;  done
   54  * through a call to @c le_thread_Cancel().
   55  *
   56  * If a thread terminates itself, and it is "joinable", it can pass a @c void* value to another
   57  * thread that "joins" with it.  See @ref threadJoining for more information.
   58  *
   59  * Canceling a thread may not cause the thread to terminate immediately.  If it is
   60  * in the middle of doing something that can't be interrupted, it will not terminate until it
   61  * is finished.  See 'man 7 pthreads' for more information on cancellation
   62  * and cancellation points.
   63  *
   64  * To prevent cancellation during a critical section (e.g., when a mutex lock is held),
   65  * pthread_setcancelstate() can be called.  If a cancellation request is made (by calling
   66  * le_thread_Cancel() or <c>pthread_cancel()</c>), it will be blocked and remain in a pending state
   67  * until cancellation is unblocked (also using pthread_setcancelstate()), at which time the thread
   68  * will be immediately cancelled.
   69  *
   70  *
   71  * @section threadJoining Joining
   72  *
   73  * Sometimes, you want single execution thread split (fork) into separate
   74  * threads of parallel execution and later join back together into one thread later.  Forking
   75  * is done by creating and starting a thread. Joining is done by a call to le_thread_Join().
   76  * le_thread_Join(T) blocks the calling thread until thread T exits.
   77  *
   78  * For a thread to be joinable, it must have its "joinable" attribute set (using
   79  * le_thread_SetJoinable()) prior to being started.  Normally, when a thread terminates, it
   80  * disappears.  But, a joinable thread doesn't disappear until another thread "joins" with it.
   81  * This also means that if a thread is joinable, someone must join with it, or its
   82  * resources will never get cleaned up (until the process terminates).
   83  *
   84  * le_thread_Join() fetches the return/exit value of the thread that it joined with.
   85  *
   86  *
   87  * @section threadLocalData Thread-Local Data
   88  *
   89  * Often, you want data specific to a particular thread.  A classic example
   90  * of is the ANSI C variable @c errno. If one instance of @c errno was shared by all the
   91  * threads in the process, then it would essentially become useless in a multi-threaded program
   92  * because it would be impossible to ensure another thread hadn't killed @c errno before
   93  * its value could be read.  As a result, POSIX has mandated that @c errno be a @a thread-local
   94  * variable; each thread has its own unique copy of @c errno.
   95  *
   96  * If a component needs to make use of other thread-local data, it can do so using the pthread
   97  * functions pthread_key_create(), pthread_getspecific(), pthread_setspecific(),
   98  * pthread_key_delete().  See the pthread man pages for more details.
   99  *
  100  *
  101  * @section threadSynchronization Thread Synchronization
  102  *
  103  * Nasty multi-threading defects arise as a result of thread synchronization, or a
  104  * lack of synchronization.  If threads share data, they @b MUST be synchronized with each other to
  105  * avoid destroying that data and incorrect thread behaviour.
  106  *
  107  * @warning This documentation assumes that the reader is familiar with multi-thread synchronization
  108  * techniques and mechanisms.
  109  *
  110  * The Legato C APIs provide the following thread synchronization mechanisms:
  111  *  - @ref c_mutex
  112  *  - @ref c_semaphore
  113  *  - @ref c_messaging
  114  *
  115  *
  116  * @section threadDestructors Thread Destructors
  117  *
  118  * When a thread dies, some clean-up action is needed (e.g., a connection
  119  * needs to be closed or some objects need to be released).  If a thread doesn't always terminate
  120  * the same way (e.g., if it might be canceled by another thread or exit in several places due
  121  * to error detection code), then a clean-up function (destructor) is probably needed.
  122  *
  123  * A Legato thread can use @c le_thread_AddDestructor() to register a function to be called
  124  * by that thread just before it terminates.
  125  *
  126  * A parent thread can also call @c le_thread_AddChildDestructor() to register
  127  * a destructor for a child thread before it starts the child thread.
  128  *
  129  * Multiple destructors can be registered for the same thread.  They will be called in reverse
  130  * order of registration (i.e, the last destructor to be registered will be called first).
  131  *
  132  * A Legato thread can also use le_thread_RemoveDestructor() to remove its own destructor
  133  * function that it no longer wants called in the event of its death.  (There is no way to remove
  134  * destructors from other threads.)
  135  *
  136  *
  137  * @section threadLegatoizing Using Legato APIs from Non-Legato Threads
  138  *
  139  * If a thread is started using some other means besides le_thread_Start() (e.g., if
  140  * pthread_create() is used directly), then the Legato thread-specific data will not have
  141  * been initialized for that thread.  Therefore, if that thread tries to call some Legato APIs,
  142  * a fatal error message like, "Legato threading API used in non-Legato thread!" may be seen.
  143  *
  144  * To work around this, a "non-Legato thread" can call le_thread_InitLegatoThreadData() to
  145  * initialize the thread-specific data that the Legato framework needs.
  146  *
  147  * If you have done this for a thread, and that thread will die before the process it is inside
  148  * dies, then that thread must call le_thread_CleanupLegatoThreadData() before it exits.  Otherwise
  149  * the process will leak memory.  Furthermore, if the thread will ever be cancelled by another
  150  * thread before the process dies, a cancellation clean-up handler can be used to ensure that
  151  * the clean-up is done, if the thread's cancellation type is set to "deferred".
  152  * See 'man 7 pthreads' for more information on cancellation and cancellation points.
  153  *
  154  *
  155  * <HR>
  156  *
  157  * Copyright (C) Sierra Wireless Inc.
  158  */
  159 
  160 
  161 /** @file le_thread.h
  162  *
  163  * Legato @ref c_threading include file.
  164  *
  165  * Copyright (C) Sierra Wireless Inc.
  166  */
  167 
  168 #ifndef LEGATO_THREAD_INCLUDE_GUARD
  169 #define LEGATO_THREAD_INCLUDE_GUARD
  170 
  171 #include "le_cdata.h"
  172 
  173 //--------------------------------------------------------------------------------------------------
  174 /**
  175  * Reference to a thread of execution.
  176  *
  177  * @note NULL can be used as an invalid value.
  178  */
  179 //--------------------------------------------------------------------------------------------------
  180 typedef struct le_thread* le_thread_Ref_t;
  181 
  182 
  183 //--------------------------------------------------------------------------------------------------
  184 /**
  185  * Thread priority levels.
  186  *
  187  * Real-time priority levels should be avoided unless absolutely necessary for the application.
  188  * They are privileged levels and will therefore not be allowed unless the application is executed
  189  * by an identity with the appropriate permissions.  If a thread running at a real-time priority
  190  * level does not block, no other thread at a lower priority level will run, so be careful with
  191  * these.
  192  *
  193  * @note Higher numbers are higher priority.
  194  */
  195 //--------------------------------------------------------------------------------------------------
  196 typedef enum
  197 {
  198     LE_THREAD_PRIORITY_IDLE = 0,    ///< Lowest priority level. Only runs when nothing else to do.
  199 
  200     LE_THREAD_PRIORITY_LOW,         ///< Low, non-realtime priority level.
  201                                     ///< Low, medium, high: intended for normal processes that
  202                                     ///< contend for the CPU. Processes with these priorities don't
  203                                     ///< preempt each other, but their priorities affect how they're
  204                                     ///< inserted into the scheduling queue (high to low).
  205     LE_THREAD_PRIORITY_MEDIUM,      ///< Medium, non-real-time priority level. THIS IS THE DEFAULT.
  206     LE_THREAD_PRIORITY_HIGH,        ///< High, non-real-time priority level.
  207 
  208     LE_THREAD_PRIORITY_RT_1,        ///< Real-time priority level 1.  The lowest realtime priority
  209                                     ///  level.
  210     LE_THREAD_PRIORITY_RT_2,        ///< Real-time priority level 2.
  211     LE_THREAD_PRIORITY_RT_3,        ///< Real-time priority level 3.
  212     LE_THREAD_PRIORITY_RT_4,        ///< Real-time priority level 4.
  213     LE_THREAD_PRIORITY_RT_5,        ///< Real-time priority level 5.
  214     LE_THREAD_PRIORITY_RT_6,        ///< Real-time priority level 6.
  215     LE_THREAD_PRIORITY_RT_7,        ///< Real-time priority level 7.
  216     LE_THREAD_PRIORITY_RT_8,        ///< Real-time priority level 8.
  217     LE_THREAD_PRIORITY_RT_9,        ///< Real-time priority level 9.
  218     LE_THREAD_PRIORITY_RT_10,       ///< Real-time priority level 10.
  219     LE_THREAD_PRIORITY_RT_11,       ///< Real-time priority level 11.
  220     LE_THREAD_PRIORITY_RT_12,       ///< Real-time priority level 12.
  221     LE_THREAD_PRIORITY_RT_13,       ///< Real-time priority level 13.
  222     LE_THREAD_PRIORITY_RT_14,       ///< Real-time priority level 14.
  223     LE_THREAD_PRIORITY_RT_15,       ///< Real-time priority level 15.
  224     LE_THREAD_PRIORITY_RT_16,       ///< Real-time priority level 16.
  225     LE_THREAD_PRIORITY_RT_17,       ///< Real-time priority level 17.
  226     LE_THREAD_PRIORITY_RT_18,       ///< Real-time priority level 18.
  227     LE_THREAD_PRIORITY_RT_19,       ///< Real-time priority level 19.
  228     LE_THREAD_PRIORITY_RT_20,       ///< Real-time priority level 20.
  229     LE_THREAD_PRIORITY_RT_21,       ///< Real-time priority level 21.
  230     LE_THREAD_PRIORITY_RT_22,       ///< Real-time priority level 22.
  231     LE_THREAD_PRIORITY_RT_23,       ///< Real-time priority level 23.
  232     LE_THREAD_PRIORITY_RT_24,       ///< Real-time priority level 24.
  233     LE_THREAD_PRIORITY_RT_25,       ///< Real-time priority level 25.
  234     LE_THREAD_PRIORITY_RT_26,       ///< Real-time priority level 26.
  235     LE_THREAD_PRIORITY_RT_27,       ///< Real-time priority level 27.
  236     LE_THREAD_PRIORITY_RT_28,       ///< Real-time priority level 28.
  237     LE_THREAD_PRIORITY_RT_29,       ///< Real-time priority level 29.
  238     LE_THREAD_PRIORITY_RT_30,       ///< Real-time priority level 30.
  239     LE_THREAD_PRIORITY_RT_31,       ///< Real-time priority level 31.
  240     LE_THREAD_PRIORITY_RT_32        ///< Real-time priority level 32.
  241 }
  242 le_thread_Priority_t;
  243 
  244 #define LE_THREAD_PRIORITY_RT_LOWEST    LE_THREAD_PRIORITY_RT_1     ///< Lowest real-time priority.
  245 #define LE_THREAD_PRIORITY_RT_HIGHEST   LE_THREAD_PRIORITY_RT_32    ///< Highest real-time priority.
  246 
  247 
  248 //--------------------------------------------------------------------------------------------------
  249 /**
  250  * Main functions for threads must look like this:
  251  *
  252  * @param   context [IN] Context value that was passed to le_thread_Create().
  253  *
  254  * @return  Thread result value. If the thread is joinable, then this value can be obtained by
  255  *          another thread through a call to vt_thread_Join().  Otherwise, the return value is ignored.
  256  */
  257 //--------------------------------------------------------------------------------------------------
  258 typedef void* (* le_thread_MainFunc_t)
  259 (
  260     void* context   ///< See parameter documentation above.
  261 );
  262 
  263 
  264 #if LE_CONFIG_THREAD_NAMES_ENABLED
  265 //--------------------------------------------------------------------------------------------------
  266 /**
  267  * Creates a new Legato thread of execution.  After creating the thread, you have the opportunity
  268  * to set attributes before it starts.  It won't start until le_thread_Start() is called.
  269  *
  270  *  @param[in]  name        Thread name (will be copied, so can be temporary).
  271  *  @param[in]  mainFunc    Thread's main function.
  272  *  @param[in]  context     Value to pass to mainFunc when it is called.
  273  *
  274  *  @return A reference to the thread (doesn't return if fails).
  275  */
  276 //--------------------------------------------------------------------------------------------------
  277 le_thread_Ref_t le_thread_Create
  278 (
  279     const char*             name,
  280     le_thread_MainFunc_t    mainFunc,
  281     void*                   context
  282 );
  283 #else /* if not LE_CONFIG_THREAD_NAMES_ENABLED */
  284 /// @cond HIDDEN_IN_USER_DOCS
  285 //--------------------------------------------------------------------------------------------------
  286 /**
  287  * Internal function used to implement le_thread_Create().
  288  */
  289 //--------------------------------------------------------------------------------------------------
  290 le_thread_Ref_t _le_thread_Create(le_thread_MainFunc_t mainFunc, void* context);
  291 /// @endcond
  292 //--------------------------------------------------------------------------------------------------
  293 /**
  294  * Creates a new Legato thread of execution.  After creating the thread, you have the opportunity
  295  * to set attributes before it starts.  It won't start until le_thread_Start() is called.
  296  *
  297  *  @param[in]  name        Thread name (will be copied, so can be temporary).
  298  *  @param[in]  mainFunc    Thread's main function.
  299  *  @param[in]  context     Value to pass to mainFunc when it is called.
  300  *
  301  *  @return A reference to the thread (doesn't return if fails).
  302  */
  303 //--------------------------------------------------------------------------------------------------
  304 LE_DECLARE_INLINE le_thread_Ref_t le_thread_Create
  305 (
  306     const char*             name,
  307     le_thread_MainFunc_t    mainFunc,
  308     void*                   context
  309 )
  310 {
  311     return _le_thread_Create(mainFunc, context);
  312 }
  313 #endif /* end LE_CONFIG_THREAD_NAMES_ENABLED */
  314 
  315 
  316 //--------------------------------------------------------------------------------------------------
  317 /**
  318  * Sets the priority of a thread.
  319  *
  320  * @return
  321  *      - LE_OK if successful.
  322  *      - LE_OUT_OF_RANGE if the priority level requested is out of range.
  323  */
  324 //--------------------------------------------------------------------------------------------------
  325 le_result_t le_thread_SetPriority
  326 (
  327     le_thread_Ref_t         thread,     ///< [IN]
  328     le_thread_Priority_t    priority    ///< [IN]
  329 );
  330 
  331 
  332 //--------------------------------------------------------------------------------------------------
  333 /**
  334  * Sets the stack size of a thread.
  335  *
  336  * @note It's generally not necessary to set the stack size.  Some reasons why you might are:
  337  *         - to increase it beyond the system's default stack size to prevent overflow
  338  *              for a thread that makes extremely heavy use of the stack;
  339  *         - to decrease it to save memory when:
  340  *            - running in a system that does not support virtual memory
  341  *            - the thread has very tight real-time constraints that require that the stack
  342  *                  memory be locked into physical memory to avoid page faults.
  343  *
  344  * @return
  345  *      - LE_OK if successful.
  346  *      - LE_OVERFLOW if the stack size requested is too small.
  347  *      - LE_OUT_OF_RANGE if the stack size requested is too large.
  348  */
  349 //--------------------------------------------------------------------------------------------------
  350 le_result_t le_thread_SetStackSize
  351 (
  352     le_thread_Ref_t     thread,     ///< [IN]
  353     size_t              size        ///< [IN] Stack size, in bytes.  May be rounded up to the
  354                                     ///       nearest virtual memory page size.
  355 );
  356 
  357 
  358 //--------------------------------------------------------------------------------------------------
  359 /**
  360  *  Define a static thread stack region.
  361  *
  362  *  @param  name    Stack variable name.
  363  *  @param  bytes   Number of bytes in the stack.
  364  */
  365 //--------------------------------------------------------------------------------------------------
  366 #define LE_THREAD_DEFINE_STATIC_STACK(name, bytes)                                  \
  367     static uint8_t _thread_stack_##name[LE_THREAD_STACK_EXTRA_SIZE +                \
  368         ((bytes) < LE_THREAD_STACK_MIN_SIZE ? LE_THREAD_STACK_MIN_SIZE : (bytes))]  \
  369         __attribute__((aligned(LE_THREAD_STACK_ALIGNMENT)))
  370 
  371 
  372 //--------------------------------------------------------------------------------------------------
  373 /**
  374  *  Set a static stack for a thread.
  375  *
  376  *  @see le_thread_SetStack() for details.
  377  *
  378  *  @param  thread  Thread to set the stack for.
  379  *  @param  name    Stack variable name that was previously passed to
  380  *                  LE_THREAD_DEFINE_STATIC_STACK().
  381  *
  382  *  @return Return value of le_thread_SetStack().
  383  */
  384 //--------------------------------------------------------------------------------------------------
  385 #define LE_THREAD_SET_STATIC_STACK(thread, name) \
  386     le_thread_SetStack((thread), &_thread_stack_##name, sizeof(_thread_stack_##name))
  387 
  388 
  389 //--------------------------------------------------------------------------------------------------
  390 /**
  391  *  Sets the stack of a thread.
  392  *
  393  *  Setting the stack explicitly allows the caller to control the memory allocation of the thread's
  394  *  stack and, in some cases, control data.  This can be useful for allocating the space out of
  395  *  static memory, for example.
  396  *
  397  *  The macro LE_THREAD_DEFINE_STATIC_STACK() may be used to create a statically allocated stack for
  398  *  use with this function, and LE_THREAD_SET_STATIC_STACK() may be used to call it properly.
  399  *
  400  *  @attention  In general, this function is only useful on embedded, RTOS based systems in order to
  401  *              perform up-front allocation of thread resources.  On more capable systems it is
  402  *              safer to allow the operating system to set up the stack (which may optionally be
  403  *              sized using le_thread_SetStackSize()).
  404  *
  405  *  @return
  406  *      - LE_OK if successful.
  407  *      - LE_BAD_PARAMETER if the size or stack is invalid (NULL or improperly aligned).
  408  */
  409 //--------------------------------------------------------------------------------------------------
  410 le_result_t le_thread_SetStack
  411 (
  412     le_thread_Ref_t  thread,    ///< [IN] Thread instance.
  413     void            *stack,     ///< [IN] Address of the lowest byte of the stack.  This must be
  414                                 ///       appropriately aligned (LE_THREAD_DEFINE_STATIC_STACK()
  415                                 ///       will do this).
  416     size_t           size       ///< [IN] Stack size, in bytes.
  417 );
  418 
  419 
  420 //--------------------------------------------------------------------------------------------------
  421 /**
  422  * Makes a thread "joinable", meaning that when it finishes, it will remain in existence until
  423  * another thread "joins" with it by calling le_thread_Join().  By default, threads are not
  424  * joinable and will be destroyed automatically when they finish.
  425  */
  426 //--------------------------------------------------------------------------------------------------
  427 void le_thread_SetJoinable
  428 (
  429     le_thread_Ref_t         thread  ///< [IN]
  430 );
  431 
  432 
  433 //--------------------------------------------------------------------------------------------------
  434 /**
  435  * Starts a new Legato execution thread.  After creating the thread, you have the opportunity
  436  * to set attributes before it starts.  It won't start until le_thread_Start() is called.
  437  */
  438 //--------------------------------------------------------------------------------------------------
  439 void le_thread_Start
  440 (
  441     le_thread_Ref_t     thread      ///< [IN]
  442 );
  443 
  444 
  445 //--------------------------------------------------------------------------------------------------
  446 /**
  447  * "Joins" the calling thread with another thread.  Blocks the calling thread until the other
  448  * thread finishes.
  449  *
  450  * After a thread has been joined with, its thread reference is no longer valid and must never
  451  * be used again.
  452  *
  453  * The other thread's result value (the value it returned from its main function or passed into
  454  * le_thread_Exit()) can be obtained.
  455  *
  456  * @return
  457  *      - LE_OK if successful.
  458  *      - LE_DEADLOCK if a thread tries to join with itself or two threads try to join each other.
  459  *      - LE_NOT_FOUND if the other thread doesn't exist.
  460  *      - LE_NOT_POSSIBLE if the other thread can't be joined with.
  461  * @deprecated the result code LE_NOT_POSSIBLE is scheduled to be removed before 15.04
  462  *
  463  * @warning The other thread must be "joinable".  See le_thread_SetJoinable();
  464  *
  465  * @warning It's an error for two or more threads try to join with the same thread.
  466  */
  467 //--------------------------------------------------------------------------------------------------
  468 le_result_t le_thread_Join
  469 (
  470     le_thread_Ref_t     thread,         ///< [IN]
  471     void**              resultValuePtr  ///< [OUT] Ptr to where the finished thread's result value
  472                                         ///        will be stored.  Can be NULL if the result is
  473                                         ///        not needed.
  474 );
  475 
  476 
  477 //--------------------------------------------------------------------------------------------------
  478 /**
  479  * Terminates the calling thread.
  480  */
  481 //--------------------------------------------------------------------------------------------------
  482 void le_thread_Exit
  483 (
  484     void*   resultValue     ///< [IN] Result value.  If this thread is joinable, this result
  485                             ///         can be obtained by another thread calling le_thread_Join()
  486                             ///         on this thread.
  487 );
  488 
  489 
  490 //--------------------------------------------------------------------------------------------------
  491 /**
  492  * Tells another thread to terminate.  Returns immediately, but the termination of the
  493  * thread happens asynchronously and is not guaranteed to occur when this function returns.
  494  *
  495  * @note This function is not available on RTOS.
  496 
  497  *
  498  * @return
  499  *      - LE_OK if successful.
  500  *      - LE_NOT_FOUND if the thread doesn't exist.
  501  */
  502 //--------------------------------------------------------------------------------------------------
  503 LE_FULL_API le_result_t le_thread_Cancel
  504 (
  505     le_thread_Ref_t threadToCancel  ///< [IN] Thread to cancel.
  506 );
  507 
  508 
  509 //--------------------------------------------------------------------------------------------------
  510 /**
  511  * Causes the calling thread to sleep.
  512  *
  513  * @return
  514  *      -  0 if the sleep is successful.
  515  *      - -1 if the call is interrupted by a signal handler or encounters an error.
  516  *
  517  * @note This function is not a full equivalence of nanosleep() as the remaining sleep time will not
  518  *       be available to the caller if nanosleep() returns due to being interrupted by a signal.
  519  */
  520 //--------------------------------------------------------------------------------------------------
  521 int le_thread_Sleep
  522 (
  523     unsigned int seconds  ///< [IN] Time to sleep in seconds.
  524 );
  525 
  526 
  527 //--------------------------------------------------------------------------------------------------
  528 /**
  529  * Gets the calling thread's thread reference.
  530  *
  531  * @return  Calling thread's thread reference.
  532  */
  533 //--------------------------------------------------------------------------------------------------
  534 le_thread_Ref_t le_thread_GetCurrent
  535 (
  536     void
  537 );
  538 
  539 
  540 //--------------------------------------------------------------------------------------------------
  541 /**
  542  * Gets the name of a given thread.
  543  */
  544 //--------------------------------------------------------------------------------------------------
  545 void le_thread_GetName
  546 (
  547     le_thread_Ref_t threadRef,  ///< [IN] Thread to get the name for.
  548     char* buffPtr,              ///< [OUT] Buffer to store the name of the thread.
  549     size_t buffSize             ///< [IN] Size of the buffer.
  550 );
  551 
  552 
  553 //--------------------------------------------------------------------------------------------------
  554 /**
  555  * Gets the name of the calling thread.
  556  */
  557 //--------------------------------------------------------------------------------------------------
  558 const char* le_thread_GetMyName
  559 (
  560     void
  561 );
  562 
  563 
  564 //--------------------------------------------------------------------------------------------------
  565 /**
  566  * Destructor functions for threads must look like this:
  567  *
  568  * @param context [IN] Context parameter that was passed into le_thread_SetDestructor() when
  569  *                      this destructor was registered.
  570  */
  571 //--------------------------------------------------------------------------------------------------
  572 typedef void (* le_thread_Destructor_t)
  573 (
  574     void* context   ///< [IN] Context parameter that was passed into le_thread_SetDestructor() when
  575                     ///       this destructor was registered.
  576 );
  577 
  578 
  579 //--------------------------------------------------------------------------------------------------
  580 /**
  581  * Reference to a registered destructor function.
  582  */
  583 //--------------------------------------------------------------------------------------------------
  584 typedef struct le_thread_Destructor* le_thread_DestructorRef_t;
  585 
  586 
  587 //--------------------------------------------------------------------------------------------------
  588 /**
  589  * Registers a destructor function for the calling thread.  The destructor will be called by that
  590  * thread just before it terminates.
  591  *
  592  * A thread can register (or remove) its own destructor functions any time.
  593  *
  594  * @return Reference to the destructor that can be passed to le_thread_RemoveDestructor().
  595  *
  596  * See @ref threadDestructors for more information on destructors.
  597  */
  598 //--------------------------------------------------------------------------------------------------
  599 le_thread_DestructorRef_t le_thread_AddDestructor
  600 (
  601     le_thread_Destructor_t  destructor, ///< [IN] Function to be called.
  602     void*                   context     ///< [IN] Parameter to pass to the destructor.
  603 );
  604 
  605 
  606 //--------------------------------------------------------------------------------------------------
  607 /**
  608  * Registers a destructor function for a child thread.  The destructor will be called by the
  609  * child thread just before it terminates.
  610  *
  611  * This can only be done before the child thread is started.  After that, only the child thread
  612  * can add its own destructors.
  613  *
  614  * The reason for allowing another thread to register a destructor function is to
  615  * avoid a race condition that can cause resource leakage when a parent thread passes dynamically
  616  * allocated resources to threads that they create. This is only a problem if the child thread
  617  * is expected to release the resources when they are finished with them, and the child thread
  618  * may get cancelled at any time.
  619  *
  620  * For example, a thread @e T1 could allocate an object from a memory pool, create a thread @e T2,
  621  * and pass that object to @e T2 for processing and release.  @e T2 could register a destructor
  622  * function to release the resource whenever it terminates, whether through cancellation or
  623  * normal exit.  But, if it's possible that @e T2 could get cancelled before it even has a
  624  * chance to register a destructor function for itself, the memory pool object could never get
  625  * released.  So, we allow @e T1 to register a destructor function for @e T2 before starting @e T2.
  626  *
  627  * See @ref threadDestructors for more information on destructors.
  628  */
  629 //--------------------------------------------------------------------------------------------------
  630 void le_thread_AddChildDestructor
  631 (
  632     le_thread_Ref_t         thread,     ///< [IN] Thread to attach the destructor to.
  633     le_thread_Destructor_t  destructor, ///< [IN] Function to be called.
  634     void*                   context     ///< [IN] Parameter to pass to the destructor.
  635 );
  636 
  637 
  638 //--------------------------------------------------------------------------------------------------
  639 /**
  640  * Removes a destructor function from the calling thread's list of destructors.
  641  */
  642 //--------------------------------------------------------------------------------------------------
  643 void le_thread_RemoveDestructor
  644 (
  645     le_thread_DestructorRef_t  destructor ///< [in] Reference to the destructor to remove.
  646 );
  647 
  648 //--------------------------------------------------------------------------------------------------
  649 /**
  650  * Gets the calling thread's component instance data record.
  651  */
  652 //--------------------------------------------------------------------------------------------------
  653 const _le_cdata_ThreadRec_t *_le_thread_GetCDataInstancePtr
  654 (
  655     void
  656 );
  657 
  658 //--------------------------------------------------------------------------------------------------
  659 /**
  660  * Sets the calling thread's component instance data record.
  661  */
  662 //--------------------------------------------------------------------------------------------------
  663 void _le_thread_SetCDataInstancePtr
  664 (
  665     const _le_cdata_ThreadRec_t *cdataPtr   ///< CData instance for the thread.
  666 );
  667 
  668 #if LE_CONFIG_THREAD_NAMES_ENABLED
  669 //--------------------------------------------------------------------------------------------------
  670 /**
  671  * Initialize the thread-specific data needed by the Legato framework for the calling thread.
  672  *
  673  * This is used to turn a non-Legato thread (a thread that was created using a non-Legato API,
  674  * such as pthread_create() ) into a Legato thread.
  675  *
  676  *  @param[in]  name    A name for the thread (will be copied, so can be temporary).
  677  *
  678  *  @note This is not needed if the thread was started using le_thread_Start().
  679  **/
  680 //--------------------------------------------------------------------------------------------------
  681 void le_thread_InitLegatoThreadData
  682 (
  683     const char* name
  684 );
  685 #else /* if not LE_CONFIG_THREAD_NAMES_ENABLED */
  686 /// @cond HIDDEN_IN_USER_DOCS
  687 //--------------------------------------------------------------------------------------------------
  688 /**
  689  * Internal function used to implement le_thread_InitLegatoThreadData().
  690  */
  691 //--------------------------------------------------------------------------------------------------
  692 void _le_thread_InitLegatoThreadData(void);
  693 /// @endcond
  694 //--------------------------------------------------------------------------------------------------
  695 /**
  696  * Initialize the thread-specific data needed by the Legato framework for the calling thread.
  697  *
  698  * This is used to turn a non-Legato thread (a thread that was created using a non-Legato API,
  699  * such as pthread_create() ) into a Legato thread.
  700  *
  701  *  @param[in]  name    A name for the thread (will be copied, so can be temporary).
  702  *
  703  *  @note This is not needed if the thread was started using le_thread_Start().
  704  **/
  705 //--------------------------------------------------------------------------------------------------
  706 LE_DECLARE_INLINE void le_thread_InitLegatoThreadData
  707 (
  708     const char* name
  709 )
  710 {
  711     _le_thread_InitLegatoThreadData();
  712 }
  713 #endif /* end LE_CONFIG_THREAD_NAMES_ENABLED */
  714 
  715 
  716 //--------------------------------------------------------------------------------------------------
  717 /**
  718  * Clean-up the thread-specific data that was initialized using le_thread_InitLegatoThreadData().
  719  *
  720  * To prevent memory leaks, this must be called by the thread when it dies (unless the whole
  721  * process is dying).
  722  *
  723  * @note This is not needed if the thread was started using le_thread_Start().
  724  **/
  725 //--------------------------------------------------------------------------------------------------
  726 void le_thread_CleanupLegatoThreadData
  727 (
  728     void
  729 );
  730 
  731 
  732 #endif // LEGATO_THREAD_INCLUDE_GUARD
_le_cdata_MapEntry_t
Definition: le_cdata.h:57
le_result_t
le_result_t
Definition: le_basics.h:45
LE_FULL_API
#define LE_FULL_API
Definition: le_apiFeatures.h:40
LE_DECLARE_INLINE
#define LE_DECLARE_INLINE
Definition: le_basics.h:330
le_cdata.h