le_mem.h

    1 /**
    2  * @page c_memory Dynamic Memory Allocation API
    3  *
    4  *
    5  * @ref le_mem.h "API Reference"
    6  *
    7  * <HR>
    8  *
    9  * Dynamic memory allocation (especially deallocation) using the C runtime heap, through
   10  * malloc, free, strdup, calloc, realloc, etc. can result in performance degradation and out-of-memory
   11  * conditions.
   12  *
   13  * This is due to fragmentation of the heap. The degraded performance and exhausted memory result from indirect interactions
   14  * within the heap between unrelated application code. These issues are non-deterministic,
   15  * and can be very difficult to rectify.
   16  *
   17  * Memory Pools offer a powerful solution.  They trade-off a deterministic amount of
   18  * memory for
   19  *  - deterministic behaviour,
   20  *  - O(1) allocation and release performance, and
   21  *  - built-in memory allocation tracking.
   22  *
   23  * And it brings the power of @b destructors to C!
   24  *
   25  * @todo
   26  *     Do we need to add a "resettable heap" option to the memory management tool kit?
   27  *
   28  *
   29  * @section mem_overview Overview
   30  *
   31  * The most basic usage involves:
   32  *  - Creating a pool (usually done once at process start-up)
   33  *  - Allocating objects (memory blocks) from a pool
   34  *  - Releasing objects back to their pool.
   35  *
   36  * Pools generally can't be deleted.  You create them when your process
   37  * starts-up, and use them until your process terminates. It's up to the OS to clean-up the memory
   38  * pools, along with everything else your process is using, when your process terminates.  (Although,
   39  * if you find yourself really needing to delete pools, @ref mem_sub_pools could offer you a solution.)
   40  *
   41  * Pools also support the following advanced features:
   42  *  - reference counting
   43  *  - destructors
   44  *  - statistics
   45  *  - multi-threading
   46  *  - sub-pools (pools that can be deleted).
   47  *
   48  * The following sections describe these, beginning with the most basic usage and working up to more
   49  * advanced topics.
   50  *
   51  *
   52  * @section mem_creating Creating a Pool
   53  *
   54  * Before allocating memory from a pool, the pool must be created using le_mem_CreatePool(), passing
   55  * it the name of the pool and the size of the objects to be allocated from that pool. This returns
   56  * a reference to the new pool, which has zero free objects in it.
   57  *
   58  * To populate your new pool with free objects, you call @c le_mem_ExpandPool().
   59  * This is separated into two functions (rather than having
   60  * one function with three parameters) to make it virtually impossible to accidentally get the parameters
   61  * in the wrong order (which would result in nasty bugs that couldn't be caught by the compiler).
   62  * The ability to expand pools comes in handy (see @ref mem_pool_sizes).
   63  *
   64  * This code sample defines a class "Point" and a pool "PointPool" used to
   65  * allocate memory for objects of that class:
   66  * @code
   67  * #define MAX_POINTS 12  // Maximum number of points that can be handled.
   68  *
   69  * typedef struct
   70  * {
   71  *     int x;  // pixel position along x-axis
   72  *     int y;  // pixel position along y-axis
   73  * }
   74  * Point_t;
   75  *
   76  * le_mem_PoolRef_t PointPool;
   77  *
   78  * int xx_pt_ProcessStart(void)
   79  * {
   80  *     PointPool = le_mem_CreatePool("xx.pt.Points", sizeof(Point_t));
   81  *     le_mem_ExpandPool(PointPool, MAX_POINTS);
   82  *
   83  *     return SUCCESS;
   84  * }
   85  * @endcode
   86  *
   87  * To make things easier for power-users, @c le_mem_ExpandPool() returns the same pool
   88  * reference that it was given. This allows the xx_pt_ProcessStart() function to be re-implemented
   89  * as follows:
   90  * @code
   91  * int xx_pt_ProcessStart(void)
   92  * {
   93  *     PointPool = le_mem_ExpandPool(le_mem_CreatePool(sizeof(Point_t)), MAX_POINTS);
   94  *
   95  *     return SUCCESS;
   96  * }
   97  * @endcode
   98  *
   99  * Although this requires a dozen or so fewer keystrokes of typing and occupies one less line
  100  * of code, it's arguably less readable than the previous example.
  101  *
  102  * For a discussion on how to pick the number of objects to have in your pools, see @ref mem_pool_sizes.
  103  *
  104  * @section mem_allocating Allocating From a Pool
  105  *
  106  * Allocating from a pool has multiple options:
  107  *  - @c le_mem_TryAlloc() - Quietly return NULL if there are no free blocks in the pool.
  108  *  - @c le_mem_AssertAlloc() - Log an error and take down the process if there are no free blocks in
  109  *                         the pool.
  110  *  - @c le_mem_ForceAlloc() - If there are no free blocks in the pool, log a warning and automatically
  111  *                         expand the pool (or log an error and terminate the calling process there's
  112  *                         not enough free memory to expand the pool).
  113  *
  114  * All of these functions take a pool reference and return a pointer to the object
  115  * allocated from the pool.
  116  *
  117  * The first option, using @c le_mem_TryAlloc(), is the
  118  *  closest to the way good old malloc() works.  It requires the caller check the
  119  * return code to see if it's NULL.  This can be annoying enough that a lot of
  120  * people get lazy and don't check the return code (Bad programmer! Bad!). It turns out that
  121  * this option isn't really what people usually want (but occasionally they do)
  122  *
  123  * The second option, using @c le_mem_AssertAlloc(), is only used when the allocation should
  124  * never fail, by design; a failure to allocate a block is a fatal error.
  125  * This isn't often used, but can save a lot of boilerplate error checking code.
  126  *
  127  * The third option, @c using le_mem_ForceAlloc(), is the one that gets used most often.
  128  * It allows developers to avoid writing error checking code, because the allocation will
  129  * essentially never fail because it's handled inside the memory allocator.  It also
  130  * allows developers to defer fine tuning their pool sizes until after they get things working.
  131  * Later, they check the logs for pool size usage, and then modify their pool sizes accordingly.
  132  * If a particular pool is continually growing, it's a good indication there's a
  133  * memory leak. This permits seeing exactly what objects are being leaked.  If certain debug
  134  * options are turned on, they can even find out which line in which file allocated the blocks
  135  *  being leaked.
  136  *
  137  *
  138  * @section mem_releasing Releasing Back Into a Pool
  139  *
  140  * Releasing memory back to a pool never fails, so there's no need to check a return code.
  141  * Also, each object knows which pool it came from, so the code that releases the object doesn't have to care.
  142  * All it has to do is call @c le_mem_Release() and pass a pointer to the object to be released.
  143  *
  144  * The critical thing to remember is that once an object has been released, it
  145  * <b> must never be accessed again </b>.  Here is a <b> very bad code example</b>:
  146  * @code
  147  *     Point_t* pointPtr = le_mem_ForceAlloc(PointPool);
  148  *     pointPtr->x = 5;
  149  *     pointPtr->y = 10;
  150  *     le_mem_Release(pointPtr);
  151  *     printf("Point is at position (%d, %d).\n", pointPtr->x, pointPtr->y);
  152  * @endcode
  153  *
  154  *
  155  * @section mem_ref_counting Reference Counting
  156  *
  157  * Reference counting is a powerful feature of our memory pools.  Here's how it works:
  158  *  - Every object allocated from a pool starts with a reference count of 1.
  159  *  - Whenever someone calls le_mem_AddRef() on an object, its reference count is incremented by 1.
  160  *  - When it's released, its reference count is decremented by 1.
  161  *  - When its reference count reaches zero, it's destroyed (i.e., its memory is released back into the pool.)
  162  *
  163  * This allows one function to:
  164  *  - create an object.
  165  *  - work with it.
  166  *  - increment its reference count and pass a pointer to the object to another function (or thread, data structure, etc.).
  167  *  - work with it some more.
  168  *  - release the object without having to worry about when the other function is finished with it.
  169  *
  170  * The other function also releases the object when it's done with it.  So, the object will
  171  * exist until both functions are done.
  172  *
  173  * If there are multiple threads involved, be careful to protect the shared
  174  * object from race conditions(see the @ref mem_threading).
  175  *
  176  * Another great advantage of reference counting is it enables @ref mem_destructors.
  177  *
  178  * @note le_mem_GetRefCount() can be used to check the current reference count on an object.
  179  *
  180  * @section mem_destructors Destructors
  181  *
  182  * Destructors are a powerful feature of C++.  Anyone who has any non-trivial experience with C++ has
  183  * used them.  Because C was created before object-oriented programming was around, there's
  184  * no native language support for destructors in C.  Object-oriented design is still possible
  185  * and highly desireable even when the programming is done in C.
  186  *
  187  * In Legato, it's possible to call @c le_mem_SetDestructor() to attach a function to a memory pool
  188  * to be used as a destructor for objects allocated from that pool. If a pool has a destructor,
  189  *  whenever the reference count reaches zero for an object allocated from that pool,
  190  * the pool's destructor function will pass a pointer to that object.  After
  191  * the destructor returns, the object will be fully destroyed, and its memory will be released back
  192  * into the pool for later reuse by another object.
  193  *
  194  * Here's a destructor code sample:
  195  * @code
  196  * static void PointDestructor(void* objPtr)
  197  * {
  198  *     Point_t* pointPtr = objPtr;
  199  *
  200  *     printf("Destroying point (%d, %d)\n", pointPtr->x, pointPtr->y);
  201  *
  202  *     @todo Add more to sample.
  203  * }
  204  *
  205  * int xx_pt_ProcessStart(void)
  206  * {
  207  *     PointPool = le_mem_CreatePool(sizeof(Point_t));
  208  *     le_mem_ExpandPool(PointPool, MAX_POINTS);
  209  *     le_mem_SetDestructor(PointPool, PointDestructor);
  210  *     return SUCCESS;
  211  * }
  212  *
  213  * static void DeletePointList(Point_t** pointList, size_t numPoints)
  214  * {
  215  *     size_t i;
  216  *     for (i = 0; i < numPoints; i++)
  217  *     {
  218  *         le_mem_Release(pointList[i]);
  219  *     }
  220  * }
  221  * @endcode
  222  *
  223  * In this sample, when DeletePointList() is called (with a pointer to an array of pointers
  224  * to Point_t objects with reference counts of 1), each of the objects in the pointList is
  225  * released.  This causes their reference counts to hit 0, which triggers executing
  226  * PointDestructor() for each object in the pointList, and the "Destroying point..." message will
  227  * be printed for each.
  228  *
  229  *
  230  * @section mem_stats Statistics
  231  *
  232  * Some statistics are gathered for each memory pool:
  233  *  - Number of allocations.
  234  *  - Number of currently free objects.
  235  *  - Number of overflows (times that le_mem_ForceAlloc() had to expand the pool).
  236  *
  237  * Statistics (and other pool properties) can be checked using functions:
  238  *  - @c le_mem_GetStats()
  239  *  - @c le_mem_GetObjectCount()
  240  *  - @c le_mem_GetObjectSize()
  241  *
  242  * Statistics are fetched together atomically using a single function call.
  243  * This prevents inconsistencies between them if in a multi-threaded program.
  244  *
  245  * If you don't have a reference to a specified pool, but you have the name of the pool, you can
  246  * get a reference to the pool using @c le_mem_FindPool().
  247  *
  248  * In addition to programmatically fetching these, they're also available through the
  249  * "poolstat" console command (unless your process's main thread is blocked).
  250  *
  251  * To reset the pool statistics, use @c le_mem_ResetStats().
  252  *
  253  * @section mem_diagnostics Diagnostics
  254  *
  255  * The memory system also supports two different forms of diagnostics.  Both are enabled by defining
  256  * special preprocessor macros when building the framework.
  257  *
  258  * The first of which is @c LE_MEM_TRACE.  When you define @c LE_MEM_TRACE every pool is given a
  259  * tracepoint with the name of the pool on creation.
  260  *
  261  * For instance, the configTree node pool is called, "configTree.nodePool".  So to enable a trace of
  262  * all config tree node creation and deletion one would use the log tool as follows:
  263  *
  264  * @code
  265  * $ log trace configTree.nodePool
  266  * @endcode
  267  *
  268  * The second diagnostic build flag is @c LE_MEM_VALGRIND.  When @c LE_MEM_VALGRIND is enabled, the
  269  * pools are disabled and instead malloc and free are directly used.  Thus enabling the use of tools
  270  * like Valgrind.
  271  *
  272  * @section mem_threading Multi-Threading
  273  *
  274  * All functions in this API are <b> thread-safe, but not async-safe </b>.  The objects
  275  * allocated from pools are not inherently protected from races between threads.
  276  *
  277  * Allocating and releasing objects, checking stats, incrementing reference
  278  * counts, etc. can all be done from multiple threads (excluding signal handlers) without having
  279  * to worry about corrupting the memory pools' hidden internal data structures.
  280  *
  281  * There's no magical way to prevent different threads from interferring with each other
  282  * if they both access the @a contents of the same object at the same time.
  283  *
  284  * The best way to prevent multi-threaded race conditions is simply don't share data between
  285  * threads. If multiple threads must access the same data structure, then mutexes, semaphores,
  286  * or similar methods should be used to @a synchronize threads and avoid
  287  * data structure corruption or thread misbehaviour.
  288  *
  289  * Although memory pools are @a thread-safe, they are not @a async-safe. This means that memory pools
  290  * @a can be corrupted if they are accessed by a signal handler while they are being accessed
  291  * by a normal thread.  To be safe, <b> don't call any memory pool functions from within a signal handler. </b>
  292  *
  293  * One problem using destructor functions in a
  294  * multi-threaded environment is that the destructor function modifies a data structure shared
  295  * between threads, so it's easy to forget to synchronize calls to @c le_mem_Release() with other code
  296  *  accessing the data structure.  If a mutex is used to coordinate access to
  297  * the data structure, then the mutex must be held by the thread that calls le_mem_Release() to
  298  * ensure there's no other thread accessing the data structure when the destructor runs.
  299  *
  300  * @section mem_pool_sizes Managing Pool Sizes
  301  *
  302  * We know it's possible to have pools automatically expand
  303  * when they are exhausted, but we don't really want that to happen normally.
  304  * Ideally, the pools should be fully allocated to their maximum sizes at start-up so there aren't
  305  * any surprises later when certain feature combinations cause the
  306  * system to run out of memory in the field.  If we allocate everything we think
  307  * is needed up-front, then we are much more likely to uncover any memory shortages during
  308  * testing, before it's in the field.
  309  *
  310  * Choosing the right size for your pools correctly at start-up is easy to do if there is a maximum
  311  * number of fixed, external @a things that are being represented by the objects being allocated
  312  * from the pool.  If the pool holds "call objects" representing phone calls over a T1
  313  * carrier that will never carry more than 24 calls at a time, then it's obvious that you need to
  314  * size your call object pool at 24.
  315  *
  316  * Other times, it's not so easy to choose the pool size like
  317  * code to be reused in different products or different configurations that have different
  318  * needs.  In those cases, you still have a few options:
  319  *
  320  *  - At start-up, query the operating environment and base the pool sizes.
  321  *  - Read a configuration setting from a file or other configuration data source.
  322  *  - Use a build-time configuration setting.
  323  *
  324  * The build-time configuration setting is the easiest, and generally requires less
  325  * interaction between components at start-up simplifying APIs
  326  * and reducing boot times.
  327  *
  328  * If the pool size must be determined at start-up, use @c le_mem_ExpandPool().
  329  * Perhaps there's a service-provider module designed to allocate objects on behalf
  330  * of client. It can have multiple clients at the same time, but it doesn't know how many clients
  331  * or what their resource needs will be until the clients register with it at start-up.  We'd want
  332  * those clients to be as decoupled from each other as possible (i.e., we want the clients know as little
  333  * as possible about each other); we don't want the clients to get together and add up all
  334  * their needs before telling the service-provider.  We'd rather have the clients independently
  335  * report their own needs to the service-provider.  Also, we don't want each client to have to wait
  336  * for all the other clients to report their needs before starting to use
  337  * the services offered by the service-provider.  That would add more complexity to the interactions
  338  * between the clients and the service-provider.
  339  *
  340  * This is what should happen when the service-provider can't wait for all clients
  341  * to report their needs before creating the pool:
  342  *  - When the service-provider starts up, it creates an empty pool.
  343  *  - Whenever a client registers itself with the service-provider, the client can tell the
  344  *    service-provider what its specific needs are, and the service-provider can expand its
  345  *    object pool accordingly.
  346  *  - Since registrations happen at start-up, pool expansion occurs
  347  *    at start-up, and testing will likely find any pool sizing before going into the field.
  348  *
  349  * Where clients dynamically start and stop during runtime in response
  350  * to external events (e.g., when someone is using the device's Web UI), we still have
  351  * a problem because we can't @a shrink pools or delete pools when clients go away.  This is where
  352  * @ref mem_sub_pools is useful.
  353  *
  354  * @section mem_sub_pools Sub-Pools
  355  *
  356  * Essentially, a Sub-Pool is a memory pool that gets its blocks from another pool (the super-pool).
  357  * Sub Pools @a can be deleted, causing its blocks to be released back into the super-pool.
  358  *
  359  * This is useful when a service-provider module needs to handle clients that
  360  * dynamically pop into existence and later disappear again.  When a client attaches to the service
  361  * and says it will probably need a maximum of X of the service-provider's resources, the
  362  * service provider can set aside that many of those resources in a sub-pool for that client.
  363  * If that client goes over its limit, the sub-pool will log a warning message.
  364  *
  365  * The problem of sizing the super-pool correctly at start-up still exists,
  366  * so what's the point of having a sub-pool, when all of the resources could just be allocated from
  367  * the super-pool?
  368  *
  369  * The benefit is really gained in troubleshooting.  If client A, B, C, D and E are
  370  * all behaving nicely, but client F is leaking resources, the sub-pool created
  371  * on behalf of client F will start warning about the memory leak; time won't have to be
  372  * wasted looking at clients A through E to rule them out.
  373  *
  374  * To create a sub-pool, call @c le_mem_CreateSubPool(). It takes a reference to the super-pool
  375  * and the objects specified to the sub-pool, and it returns a reference to the new sub-pool.
  376  *
  377  * To delete a sub-pool, call @c le_mem_DeleteSubPool().  Do not try to use it to delete a pool that
  378  * was created using le_mem_CreatePool().  It's only for sub-pools created using le_mem_CreateSubPool().
  379  * Also, it's @b not okay to delete a sub-pool while there are still blocks allocated from it.
  380  * You'll see errors in your logs if you do that.
  381  *
  382  * Sub-Pools automatically inherit their parent's destructor function.
  383  *
  384  * @note You can't create sub-pools of sub-pools (i.e., sub-pools that get their blocks from another
  385  * sub-pool).
  386  *
  387  * <HR>
  388  *
  389  * Copyright (C) Sierra Wireless Inc.
  390  */
  391 
  392 //--------------------------------------------------------------------------------------------------
  393 /** @file le_mem.h
  394  *
  395  * Legato @ref c_memory include file.
  396  *
  397  * Copyright (C) Sierra Wireless Inc.
  398  *
  399  */
  400 //--------------------------------------------------------------------------------------------------
  401 
  402 #ifndef LEGATO_MEM_INCLUDE_GUARD
  403 #define LEGATO_MEM_INCLUDE_GUARD
  404 
  405 #ifndef LE_COMPONENT_NAME
  406 #define LE_COMPONENT_NAME
  407 #endif
  408 
  409 
  410 //--------------------------------------------------------------------------------------------------
  411 /**
  412  * Objects of this type are used to refer to a memory pool created using either
  413  * le_mem_CreatePool() or le_mem_CreateSubPool().
  414  */
  415 //--------------------------------------------------------------------------------------------------
  416 typedef struct le_mem_Pool* le_mem_PoolRef_t;
  417 
  418 
  419 //--------------------------------------------------------------------------------------------------
  420 /**
  421  * Prototype for destructor functions.
  422  *
  423  * @param objPtr   Pointer to the object where reference count has reached zero.  After the destructor
  424  *                 returns this object's memory will be released back into the pool (and this pointer
  425  *                 will become invalid).
  426  *
  427  * @return Nothing.
  428  *
  429  * See @ref mem_destructors for more information.
  430  */
  431 //--------------------------------------------------------------------------------------------------
  432 typedef void (*le_mem_Destructor_t)
  433 (
  434     void* objPtr    ///< see parameter documentation in comment above.
  435 );
  436 
  437 
  438 //--------------------------------------------------------------------------------------------------
  439 /**
  440  * List of memory pool statistics.
  441  */
  442 //--------------------------------------------------------------------------------------------------
  443 typedef struct
  444 {
  445     size_t      numBlocksInUse;     ///< Number of currently allocated blocks.
  446     size_t      maxNumBlocksUsed;   ///< Maximum number of allocated blocks at any one time.
  447     size_t      numOverflows;       ///< Number of times le_mem_ForceAlloc() had to expand the pool.
  448     uint64_t    numAllocs;          ///< Number of times an object has been allocated from this pool.
  449     size_t      numFree;            ///< Number of free objects currently available in this pool.
  450 }
  451 le_mem_PoolStats_t;
  452 
  453 
  454 #ifdef LE_MEM_TRACE
  455     //----------------------------------------------------------------------------------------------
  456     /**
  457      * Internal function used to retrieve a pool handle for a given pool block.
  458      */
  459     //----------------------------------------------------------------------------------------------
  460     le_mem_PoolRef_t _le_mem_GetBlockPool
  461     (
  462         void*   objPtr  ///< [IN] Pointer to the object we're finding a pool for.
  463     );
  464 
  465     typedef void* (*_le_mem_AllocFunc_t)(le_mem_PoolRef_t pool);
  466 
  467     //----------------------------------------------------------------------------------------------
  468     /**
  469      * Internal function used to call a memory allocation function and trace its call site.
  470      */
  471     //----------------------------------------------------------------------------------------------
  472     void* _le_mem_AllocTracer
  473     (
  474         le_mem_PoolRef_t     pool,             ///< [IN] The pool activity we're tracing.
  475         _le_mem_AllocFunc_t  funcPtr,          ///< [IN] Pointer to the mem function in question.
  476         const char*          poolFunction,     ///< [IN] The pool function being called.
  477         const char*          file,             ///< [IN] The file the call came from.
  478         const char*          callingfunction,  ///< [IN] The function calling into the pool.
  479         size_t               line              ///< [IN] The line in the function where the call
  480                                                ///       occurred.
  481     );
  482 
  483     //----------------------------------------------------------------------------------------------
  484     /**
  485      * Internal function used to trace memory pool activity.
  486      */
  487     //----------------------------------------------------------------------------------------------
  488     void _le_mem_Trace
  489     (
  490         le_mem_PoolRef_t    pool,             ///< [IN] The pool activity we're tracing.
  491         const char*         file,             ///< [IN] The file the call came from.
  492         const char*         callingfunction,  ///< [IN] The function calling into the pool.
  493         size_t              line,             ///< [IN] The line in the function where the call
  494                                               ///       occurred.
  495         const char*         poolFunction,     ///< [IN] The pool function being called.
  496         void*               blockPtr          ///< [IN] Block allocated/freed.
  497     );
  498 #endif
  499 
  500 
  501 //--------------------------------------------------------------------------------------------------
  502 /** @cond HIDDEN_IN_USER_DOCS
  503  *
  504  * Internal function used to implement le_mem_CreatePool() with automatic component scoping
  505  * of pool names.
  506  */
  507 //--------------------------------------------------------------------------------------------------
  508 le_mem_PoolRef_t _le_mem_CreatePool
  509 (
  510     const char* componentName,  ///< [IN] Name of the component.
  511     const char* name,           ///< [IN] Name of the pool inside the component.
  512     size_t      objSize ///< [IN] Size of the individual objects to be allocated from this pool
  513                         /// (in bytes), e.g., sizeof(MyObject_t).
  514 );
  515 /// @endcond
  516 
  517 
  518 //--------------------------------------------------------------------------------------------------
  519 /**
  520  * Creates an empty memory pool.
  521  *
  522  * @return
  523  *      Reference to the memory pool object.
  524  *
  525  * @note
  526  *      On failure, the process exits, so you don't have to worry about checking the returned
  527  *      reference for validity.
  528  */
  529 //--------------------------------------------------------------------------------------------------
  530 static inline le_mem_PoolRef_t le_mem_CreatePool
  531 (
  532     const char* name,   ///< [IN] Name of the pool (will be copied into the Pool).
  533     size_t      objSize ///< [IN] Size of the individual objects to be allocated from this pool
  534                         /// (in bytes), e.g., sizeof(MyObject_t).
  535 )
  536 {
  537     return _le_mem_CreatePool(STRINGIZE(LE_COMPONENT_NAME), name, objSize);
  538 }
  539 
  540 
  541 //--------------------------------------------------------------------------------------------------
  542 /**
  543  * Expands the size of a memory pool.
  544  *
  545  * @return  Reference to the memory pool object (the same value passed into it).
  546  *
  547  * @note    On failure, the process exits, so you don't have to worry about checking the returned
  548  *          reference for validity.
  549  */
  550 //--------------------------------------------------------------------------------------------------
  551 le_mem_PoolRef_t le_mem_ExpandPool
  552 (
  553     le_mem_PoolRef_t    pool,       ///< [IN] Pool to be expanded.
  554     size_t              numObjects  ///< [IN] Number of objects to add to the pool.
  555 );
  556 
  557 
  558 
  559 #ifndef LE_MEM_TRACE
  560     //----------------------------------------------------------------------------------------------
  561     /**
  562      * Attempts to allocate an object from a pool.
  563      *
  564      * @return
  565      *      Pointer to the allocated object, or NULL if the pool doesn't have any free objects
  566      *      to allocate.
  567      */
  568     //----------------------------------------------------------------------------------------------
  569     void* le_mem_TryAlloc
  570     (
  571         le_mem_PoolRef_t    pool    ///< [IN] Pool from which the object is to be allocated.
  572     );
  573 #else
  574     /// @cond HIDDEN_IN_USER_DOCS
  575     void* _le_mem_TryAlloc(le_mem_PoolRef_t pool);
  576     /// @endcond
  577 
  578     #define le_mem_TryAlloc(pool)                                                                   \
  579         _le_mem_AllocTracer(pool,                                                                   \
  580                             _le_mem_TryAlloc,                                                       \
  581                             "le_mem_TryAlloc",                                                      \
  582                             STRINGIZE(LE_FILENAME),                                                 \
  583                             __FUNCTION__,                                                           \
  584                             __LINE__)
  585 
  586 #endif
  587 
  588 
  589 #ifndef LE_MEM_TRACE
  590     //----------------------------------------------------------------------------------------------
  591     /**
  592      * Allocates an object from a pool or logs a fatal error and terminates the process if the pool
  593      * doesn't have any free objects to allocate.
  594      *
  595      * @return Pointer to the allocated object.
  596      *
  597      * @note    On failure, the process exits, so you don't have to worry about checking the
  598      *          returned pointer for validity.
  599      */
  600     //----------------------------------------------------------------------------------------------
  601     void* le_mem_AssertAlloc
  602     (
  603         le_mem_PoolRef_t    pool    ///< [IN] Pool from which the object is to be allocated.
  604     );
  605 #else
  606     /// @cond HIDDEN_IN_USER_DOCS
  607     void* _le_mem_AssertAlloc(le_mem_PoolRef_t pool);
  608     /// @endcond
  609 
  610     #define le_mem_AssertAlloc(pool)                                                                \
  611         _le_mem_AllocTracer(pool,                                                                   \
  612                             _le_mem_AssertAlloc,                                                    \
  613                             "le_mem_AssertAlloc",                                                   \
  614                             STRINGIZE(LE_FILENAME),                                                 \
  615                             __FUNCTION__,                                                           \
  616                             __LINE__)
  617 #endif
  618 
  619 
  620 #ifndef LE_MEM_TRACE
  621     //----------------------------------------------------------------------------------------------
  622     /**
  623      * Allocates an object from a pool or logs a warning and expands the pool if the pool
  624      * doesn't have any free objects to allocate.
  625      *
  626      * @return  Pointer to the allocated object.
  627      *
  628      * @note    On failure, the process exits, so you don't have to worry about checking the
  629      *          returned pointer for validity.
  630      */
  631     //----------------------------------------------------------------------------------------------
  632     void* le_mem_ForceAlloc
  633     (
  634         le_mem_PoolRef_t    pool    ///< [IN] Pool from which the object is to be allocated.
  635     );
  636 #else
  637     /// @cond HIDDEN_IN_USER_DOCS
  638     void* _le_mem_ForceAlloc(le_mem_PoolRef_t pool);
  639     /// @endcond
  640 
  641     #define le_mem_ForceAlloc(pool)                                                                 \
  642         _le_mem_AllocTracer(pool,                                                                   \
  643                             _le_mem_ForceAlloc,                                                     \
  644                             "le_mem_ForceAlloc",                                                    \
  645                             STRINGIZE(LE_FILENAME),                                                 \
  646                             __FUNCTION__,                                                           \
  647                             __LINE__)
  648 #endif
  649 
  650 
  651 //--------------------------------------------------------------------------------------------------
  652 /**
  653  * Sets the number of objects that are added when le_mem_ForceAlloc expands the pool.
  654  *
  655  * @return
  656  *      Nothing.
  657  *
  658  * @note
  659  *      The default value is one.
  660  */
  661 //--------------------------------------------------------------------------------------------------
  662 void le_mem_SetNumObjsToForce
  663 (
  664     le_mem_PoolRef_t    pool,       ///< [IN] Pool to set the number of objects for.
  665     size_t              numObjects  ///< [IN] Number of objects that is added when
  666                                     ///       le_mem_ForceAlloc expands the pool.
  667 );
  668 
  669 
  670 #ifndef LE_MEM_TRACE
  671     //----------------------------------------------------------------------------------------------
  672     /**
  673      * Releases an object.  If the object's reference count has reached zero, it will be destructed
  674      * and its memory will be put back into the pool for later reuse.
  675      *
  676      * @return
  677      *      Nothing.
  678      *
  679      * @warning
  680      *      - <b>Don't EVER access an object after releasing it.</b>  It might not exist anymore.
  681      *      - If the object has a destructor accessing a data structure shared by multiple
  682      *        threads, ensure you hold the mutex (or take other measures to prevent races) before
  683      *        releasing the object.
  684      */
  685     //----------------------------------------------------------------------------------------------
  686     void le_mem_Release
  687     (
  688         void*   objPtr  ///< [IN] Pointer to the object to be released.
  689     );
  690 #else
  691     /// @cond HIDDEN_IN_USER_DOCS
  692     void _le_mem_Release(void* objPtr);
  693     /// @endcond
  694 
  695     #define le_mem_Release(objPtr)                                                                  \
  696             _le_mem_Trace(_le_mem_GetBlockPool(objPtr),                                             \
  697                           STRINGIZE(LE_FILENAME),                                                   \
  698                           __FUNCTION__,                                                             \
  699                           __LINE__,                                                                 \
  700                           "le_mem_Release",                                                         \
  701                           (objPtr));                                                                \
  702             _le_mem_Release(objPtr);
  703 #endif
  704 
  705 
  706 #ifndef LE_MEM_TRACE
  707     //----------------------------------------------------------------------------------------------
  708     /**
  709      * Increments the reference count on an object by 1.
  710      *
  711      * See @ref mem_ref_counting for more information.
  712      */
  713     //----------------------------------------------------------------------------------------------
  714     void le_mem_AddRef
  715     (
  716         void*   objPtr  ///< [IN] Pointer to the object.
  717     );
  718 #else
  719     /// @cond HIDDEN_IN_USER_DOCS
  720     void _le_mem_AddRef(void* objPtr);
  721     /// @endcond
  722 
  723     #define le_mem_AddRef(objPtr)                                                                   \
  724         _le_mem_Trace(_le_mem_GetBlockPool(objPtr),                                                 \
  725                       STRINGIZE(LE_FILENAME),                                                       \
  726                       __FUNCTION__,                                                                 \
  727                       __LINE__,                                                                     \
  728                       "le_mem_AddRef",                                                              \
  729                       (objPtr));                                                                    \
  730         _le_mem_AddRef(objPtr);
  731 #endif
  732 
  733 
  734 //----------------------------------------------------------------------------------------------
  735 /**
  736  * Fetches the reference count on an object.
  737  *
  738  * See @ref mem_ref_counting for more information.
  739  *
  740  * @warning If using this in a multi-threaded application that shares memory pool objects
  741  *          between threads, steps must be taken to coordinate the threads (e.g., using a mutex)
  742  *          to ensure that the reference count value fetched remains correct when it is used.
  743  *
  744  * @return
  745  *      The reference count on the object.
  746  */
  747 //----------------------------------------------------------------------------------------------
  748 size_t le_mem_GetRefCount
  749 (
  750     void*   objPtr  ///< [IN] Pointer to the object.
  751 );
  752 
  753 
  754 //--------------------------------------------------------------------------------------------------
  755 /**
  756  * Sets the destructor function for a specified pool.
  757  *
  758  * See @ref mem_destructors for more information.
  759  *
  760  * @return
  761  *      Nothing.
  762  */
  763 //--------------------------------------------------------------------------------------------------
  764 void le_mem_SetDestructor
  765 (
  766     le_mem_PoolRef_t    pool,       ///< [IN] The pool.
  767     le_mem_Destructor_t destructor  ///< [IN] Destructor function.
  768 );
  769 
  770 
  771 //--------------------------------------------------------------------------------------------------
  772 /**
  773  * Fetches the statistics for a specified pool.
  774  *
  775  * @return
  776  *      Nothing.  Uses output parameter instead.
  777  */
  778 //--------------------------------------------------------------------------------------------------
  779 void le_mem_GetStats
  780 (
  781     le_mem_PoolRef_t    pool,       ///< [IN] Pool where stats are to be fetched.
  782     le_mem_PoolStats_t* statsPtr    ///< [OUT] Pointer to where the stats will be stored.
  783 );
  784 
  785 
  786 //--------------------------------------------------------------------------------------------------
  787 /**
  788  * Resets the statistics for a specified pool.
  789  *
  790  * @return
  791  *      Nothing.
  792  */
  793 //--------------------------------------------------------------------------------------------------
  794 void le_mem_ResetStats
  795 (
  796     le_mem_PoolRef_t    pool        ///< [IN] Pool where stats are to be reset.
  797 );
  798 
  799 
  800 //--------------------------------------------------------------------------------------------------
  801 /**
  802  * Gets the memory pool's name, including the component name prefix.
  803  *
  804  * If the pool were given the name "myPool" and the component that it belongs to is called
  805  * "myComponent", then the full pool name returned by this function would be "myComponent.myPool".
  806  *
  807  * @return
  808  *      LE_OK if successful.
  809  *      LE_OVERFLOW if the name was truncated to fit in the provided buffer.
  810  */
  811 //--------------------------------------------------------------------------------------------------
  812 le_result_t le_mem_GetName
  813 (
  814     le_mem_PoolRef_t    pool,       ///< [IN] The memory pool.
  815     char*               namePtr,    ///< [OUT] Buffer to store the name of the memory pool.
  816     size_t              bufSize     ///< [IN] Size of the buffer namePtr points to.
  817 );
  818 
  819 
  820 //--------------------------------------------------------------------------------------------------
  821 /**
  822  * Checks if the specified pool is a sub-pool.
  823  *
  824  * @return
  825  *      true if it is a sub-pool.
  826  *      false if it is not a sub-pool.
  827  */
  828 //--------------------------------------------------------------------------------------------------
  829 const bool le_mem_IsSubPool
  830 (
  831     le_mem_PoolRef_t    pool        ///< [IN] The memory pool.
  832 );
  833 
  834 
  835 //--------------------------------------------------------------------------------------------------
  836 /**
  837  * Fetches the number of objects a specified pool can hold (this includes both the number of
  838  * free and in-use objects).
  839  *
  840  * @return
  841  *      Total number of objects.
  842  */
  843 //--------------------------------------------------------------------------------------------------
  844 size_t le_mem_GetObjectCount
  845 (
  846     le_mem_PoolRef_t    pool        ///< [IN] Pool where number of objects is to be fetched.
  847 );
  848 
  849 
  850 //--------------------------------------------------------------------------------------------------
  851 /**
  852  * Fetches the size of the objects in a specified pool (in bytes).
  853  *
  854  * @return
  855  *      Object size, in bytes.
  856  */
  857 //--------------------------------------------------------------------------------------------------
  858 size_t le_mem_GetObjectSize
  859 (
  860     le_mem_PoolRef_t    pool        ///< [IN] Pool where object size is to be fetched.
  861 );
  862 
  863 
  864 //--------------------------------------------------------------------------------------------------
  865 /**
  866  * Fetches the total size of the object including all the memory overhead in a given pool (in bytes).
  867  *
  868  * @return
  869  *      Total object memory size, in bytes.
  870  */
  871 //--------------------------------------------------------------------------------------------------
  872 size_t le_mem_GetObjectFullSize
  873 (
  874     le_mem_PoolRef_t    pool        ///< [IN] The pool whose object memory size is to be fetched.
  875 );
  876 
  877 
  878 //--------------------------------------------------------------------------------------------------
  879 /** @cond HIDDEN_IN_USER_DOCS
  880  *
  881  * Internal function used to implement le_mem_FindPool() with automatic component scoping
  882  * of pool names.
  883  */
  884 //--------------------------------------------------------------------------------------------------
  885 le_mem_PoolRef_t _le_mem_FindPool
  886 (
  887     const char* componentName,  ///< [IN] Name of the component.
  888     const char* name            ///< [IN] Name of the pool inside the component.
  889 );
  890 /// @endcond
  891 
  892 
  893 //--------------------------------------------------------------------------------------------------
  894 /**
  895  * Finds a pool based on the pool's name.
  896  *
  897  * @return
  898  *      Reference to the pool, or NULL if the pool doesn't exist.
  899  */
  900 //--------------------------------------------------------------------------------------------------
  901 static inline le_mem_PoolRef_t le_mem_FindPool
  902 (
  903     const char* name    ///< [IN] Name of the pool.
  904 )
  905 {
  906     return _le_mem_FindPool(STRINGIZE(LE_COMPONENT_NAME), name);
  907 }
  908 
  909 
  910 //--------------------------------------------------------------------------------------------------
  911 /** @cond HIDDEN_IN_USER_DOCS
  912  *
  913  * Internal function used to implement le_mem_CreateSubPool() with automatic component scoping
  914  * of pool names.
  915  */
  916 //--------------------------------------------------------------------------------------------------
  917 le_mem_PoolRef_t _le_mem_CreateSubPool
  918 (
  919     le_mem_PoolRef_t    superPool,  ///< [IN] Super-pool.
  920     const char*     componentName,  ///< [IN] Name of the component.
  921     const char*         name,       ///< [IN] Name of the sub-pool (will be copied into the
  922                                     ///   sub-pool).
  923     size_t              numObjects  ///< [IN] Number of objects to take from the super-pool.
  924 );
  925 /// @endcond
  926 
  927 
  928 //--------------------------------------------------------------------------------------------------
  929 /**
  930  * Creates a sub-pool.  You can't create sub-pools of sub-pools so do not attempt to pass a
  931  * sub-pool in the superPool parameter.
  932  *
  933  * See @ref mem_sub_pools for more information.
  934  *
  935  * @return
  936  *      Reference to the sub-pool.
  937  */
  938 //--------------------------------------------------------------------------------------------------
  939 static inline le_mem_PoolRef_t le_mem_CreateSubPool
  940 (
  941     le_mem_PoolRef_t    superPool,  ///< [IN] Super-pool.
  942     const char*         name,       ///< [IN] Name of the sub-pool (will be copied into the
  943                                     ///   sub-pool).
  944     size_t              numObjects  ///< [IN] Number of objects to take from the super-pool.
  945 )
  946 {
  947     return _le_mem_CreateSubPool(superPool, STRINGIZE(LE_COMPONENT_NAME), name, numObjects);
  948 }
  949 
  950 
  951 //--------------------------------------------------------------------------------------------------
  952 /**
  953  * Deletes a sub-pool.
  954  *
  955  * See @ref mem_sub_pools for more information.
  956  *
  957  * @return
  958  *      Nothing.
  959  */
  960 //--------------------------------------------------------------------------------------------------
  961 void le_mem_DeleteSubPool
  962 (
  963     le_mem_PoolRef_t    subPool     ///< [IN] Sub-pool to be deleted.
  964 );
  965 
  966 
  967 #endif // LEGATO_MEM_INCLUDE_GUARD
le_mem_TryAlloc
void * le_mem_TryAlloc(le_mem_PoolRef_t pool)
le_mem_ExpandPool
le_mem_PoolRef_t le_mem_ExpandPool(le_mem_PoolRef_t pool, size_t numObjects)
le_mem_PoolStats_t::numAllocs
uint64_t numAllocs
Number of times an object has been allocated from this pool. 
Definition: le_mem.h:448
le_result_t
le_result_t
Definition: le_basics.h:35
le_mem_AssertAlloc
void * le_mem_AssertAlloc(le_mem_PoolRef_t pool)
le_mem_GetStats
void le_mem_GetStats(le_mem_PoolRef_t pool, le_mem_PoolStats_t *statsPtr)
le_mem_IsSubPool
const bool le_mem_IsSubPool(le_mem_PoolRef_t pool)
le_mem_PoolStats_t::numBlocksInUse
size_t numBlocksInUse
Number of currently allocated blocks. 
Definition: le_mem.h:445
le_mem_FindPool
static le_mem_PoolRef_t le_mem_FindPool(const char *name)
Definition: le_mem.h:902
le_mem_PoolStats_t::maxNumBlocksUsed
size_t maxNumBlocksUsed
Maximum number of allocated blocks at any one time. 
Definition: le_mem.h:446
STRINGIZE
#define STRINGIZE(x)
Definition: le_basics.h:206
le_mem_SetDestructor
void le_mem_SetDestructor(le_mem_PoolRef_t pool, le_mem_Destructor_t destructor)
le_mem_CreatePool
static le_mem_PoolRef_t le_mem_CreatePool(const char *name, size_t objSize)
Definition: le_mem.h:531
le_mem_ResetStats
void le_mem_ResetStats(le_mem_PoolRef_t pool)
le_mem_SetNumObjsToForce
void le_mem_SetNumObjsToForce(le_mem_PoolRef_t pool, size_t numObjects)
le_mem_DeleteSubPool
void le_mem_DeleteSubPool(le_mem_PoolRef_t subPool)
le_mem_PoolRef_t
struct le_mem_Pool * le_mem_PoolRef_t
Definition: le_mem.h:416
le_mem_GetName
le_result_t le_mem_GetName(le_mem_PoolRef_t pool, char *namePtr, size_t bufSize)
le_mem_Release
void le_mem_Release(void *objPtr)
le_mem_PoolStats_t::numFree
size_t numFree
Number of free objects currently available in this pool. 
Definition: le_mem.h:449
le_mem_PoolStats_t::numOverflows
size_t numOverflows
Number of times le_mem_ForceAlloc() had to expand the pool. 
Definition: le_mem.h:447
le_mem_Destructor_t
void(* le_mem_Destructor_t)(void *objPtr)
Definition: le_mem.h:433
le_mem_GetObjectCount
size_t le_mem_GetObjectCount(le_mem_PoolRef_t pool)
le_mem_PoolStats_t
Definition: le_mem.h:443
le_mem_GetObjectFullSize
size_t le_mem_GetObjectFullSize(le_mem_PoolRef_t pool)
le_mem_GetObjectSize
size_t le_mem_GetObjectSize(le_mem_PoolRef_t pool)
le_mem_AddRef
void le_mem_AddRef(void *objPtr)
le_mem_ForceAlloc
void * le_mem_ForceAlloc(le_mem_PoolRef_t pool)
le_mem_GetRefCount
size_t le_mem_GetRefCount(void *objPtr)
le_mem_CreateSubPool
static le_mem_PoolRef_t le_mem_CreateSubPool(le_mem_PoolRef_t superPool, const char *name, size_t numObjects)
Definition: le_mem.h:940