Author: Pekka Riikonen <priikone@silcnet.org>
- Copyright (C) 2003 - 2007 Pekka Riikonen
+ Copyright (C) 2003 - 2008 Pekka Riikonen
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
*
* DESCRIPTION
*
- * Implementation of data stack which can be used to allocate memory from
+ * Implementation of data stack which can be used to do fast allocations from
* the stack. Basically SilcStack is a pre-allocated memory pool system
* which allows fast memory allocation for routines and applications that
* frequently allocate small amounts of memory. Other advantage of this
* silc_buffer_sstrformat, silc_buffer_senlarge, silc_mp_sinit,
* silc_dlist_sinit, silc_hash_table_alloc
*
- * The SilcStack context is not thread-safe. If the same SilcStack must be
- * used in multithreaded environment concurrency control must be employed.
- * Each thread should allocate their own SilcStack.
+ * The SilcStack is not thread-safe so that same context could be used for
+ * allocations from multiple threads. It is however safe to create and use
+ * child stacks in a different thread from the parent stack. Each thread
+ * should allocate their own SilcStack, however they may be child stacks.
*
***/
***/
typedef struct SilcStackFrameStruct SilcStackFrame;
+/****f* silcutil/SilcStackAPI/SilcStackOomHandler
+ *
+ * SYNOPSIS
+ *
+ * typedef void (*SilcStackOomHandler)(SilcStack stack, void *context);
+ *
+ * DESCRIPTION
+ *
+ * Callback of this type can be given to silc_stack_set_oom_handler
+ * to set Out of Memory handler to `stack'. If memory allocation from
+ * `stack' fails this callback is called to indicate error. The `context'
+ * is the context given to silc_stack_set_oom_handler.
+ *
+ ***/
+typedef void (*SilcStackOomHandler)(SilcStack stack, void *context);
+
/****f* silcutil/SilcStackAPI/silc_stack_alloc
*
* SYNOPSIS
* allocation by various routines. Returns the pointer to the stack
* that must be freed with silc_stack_free function when it is not
* needed anymore. If the `stack_size' is zero (0) by default a
- * 2 kilobytes (2048 bytes) stack is allocated. If the `stack_size'
- * is non-zero the byte value must be multiple by 8.
+ * 1 kilobyte (1024 bytes) stack is allocated.
*
* If `parent' is non-NULL the created stack is a child of the `parent'
* stack. All of childs the memory is allocated from the `parent' and
* will be returned back to the parent when the child is freed. Note
- * that, even though child allocated memory from the parent, the parent's
+ * that, even though child allocates memory from the parent, the parent's
* stack is not consumed.
*
* Returns NULL on error.
* this and all allocated memory are freed.
*
* If `stack' is a child stack, its memory is returned back to its
- * parent.
+ * parent. If `stack' is NULL this function does nothing.
*
***/
void silc_stack_free(SilcStack stack);
* stack and all allocated memory is freed after the next silc_stack_pop
* is called. This returns so called stack pointer for the new stack
* frame, which the caller may use to check that all calls to
- * silc_stack_pop has been made. This call may do a small memory
- * allocation in some cases, but usually it does not allocate any memory.
- * If this returns zero (0) the system is out of memory.
+ * silc_stack_pop has been made.
*
* If the `frame' is non-NULL then that SilcStackFrame is used as
* stack frame. Usually `frame' is set to NULL by user. Statically
* allocated SilcStackFrame should be used when using silc_stack_push
* in recursive function and the recursion may become deep. In this
* case using statically allocated SilcStackFrame is recommended since
- * it assures that frames never run out and silc_stack_push never
- * allocates any memory. If your routine is not recursive then
- * setting `frame' to NULL is recommended, unless performance is
- * critical.
+ * it assures that frames never run out. If your routine is not recursive
+ * then setting `frame' to NULL is recommended.
*
* This function is used when a routine is doing frequent allocations
* from the stack. If the stack is not pushed and later popped all
* (it gets enlarged by normal memory allocation). By pushing and then
* later popping the frequent allocations does not consume the stack.
*
- * If `stack' is NULL this call has no effect.
+ * If `stack' is NULL this call has no effect. This function does not
+ * allocate any memory.
*
* EXAMPLE
*
*
* DESCRIPTION
*
- * Pop the top of the stack upwards which reveals the previous stack frame
- * and becomes the top of the stack. After popping, memory allocated in
+ * Pop the top of the stack which removes the previous stack frame and
+ * becomes the top of the stack. After popping, memory allocated in
* the old frame is freed. For each silc_stack_push call there must be
* silc_stack_pop call to free all memory (in reality any memory is not
* freed but within the stack it is). This returns the stack pointer of
* silc_stack_pop has been called too many times. Application should
* treat this as a fatal error, as it is a bug in the application code.
*
- * If `stack' is NULL this call has no effect.
+ * If `stack' is NULL this call has no effect. This function does not
+ * allocate any memory.
*
* EXAMPLE
*
*
* DESCRIPTION
*
- * Low level memory allocation routine. Allocates memor block of size of
+ * Low level memory allocation routine. Allocates memory block of size of
* `size' from the `stack'. The allocated memory is aligned so it can be
* used to allocate memory for structures, for example. Returns the
* allocated memory address or NULL if memory could not be allocated from
* NOTES
*
* This function should be used only if low level memory allocation with
- * SilcStack is needed. Instead, silc_smalloc, could be used.
+ * SilcStack is needed. Instead, silc_smalloc and silc_scalloc could
+ * be used.
*
***/
void *silc_stack_malloc(SilcStack stack, SilcUInt32 size);
* SYNOPSIS
*
* void *silc_stack_realloc(SilcStack stack, SilcUInt32 old_size,
- * *void *ptr, SilcUInt32 size);
+ * void *ptr, SilcUInt32 size);
*
* DESCRIPTION
*
* Attempts to reallocate memory by changing the size of the `ptr' into
* `size'. This routine works only if the previous allocation to `stack'
* was `ptr'. If there is another memory allocation between allocating
- * `ptr' and this call this routine will return NULL. NULL is also
- * returned if the `size' does not fit into the current block. If NULL
- * is returned the old memory remains intact.
+ * `ptr' and this call this routine will return NULL (and silc_errno is
+ * set to SILC_ERR_INVALID_ARGUMENT). NULL is also returned if the `size'
+ * does not fit into the current stack block. If NULL is returned the old
+ * memory remains intact.
*
* NOTES
*
* This function should be used only if low level memory allocation with
- * SilcStack is needed. Instead, silc_srealloc, could be used.
+ * SilcStack is needed. Instead, silc_srealloc could be used.
*
***/
void *silc_stack_realloc(SilcStack stack, SilcUInt32 old_size,
void *ptr, SilcUInt32 size);
+/****f* silcutil/SilcStackAPI/silc_stack_set_oom_handler
+ *
+ * SYNOPSIS
+ *
+ * void silc_stack_set_oom_handler(SilcStack stack,
+ * SilcStackOomHandler oom_handler,
+ * void *context);
+ *
+ * DESCRIPTION
+ *
+ * Sets Out of Memory handler `oom_handler' to `stack' to be called
+ * if memory allocation from `stack' fails. The `context' is delivered
+ * to `oom_handler'.
+ *
+ * Usually Out of Memory handler is set only when failed memory allocation
+ * is a fatal error. In this case the application would abort() inside
+ * the `oom_handler'. It may also be set if in case of failed allocation
+ * application wants to do clean up properly.
+ *
+ ***/
+void silc_stack_set_oom_handler(SilcStack stack,
+ SilcStackOomHandler oom_handler,
+ void *context);
+
/****f* silcutil/SilcStackAPI/silc_stack_set_alignment
*
* SYNOPSIS
* Sets/changes the memory alignment in the `stack' to `alignment' which
* is the alignment in bytes. By default, the SilcStack will use alignment
* suited for the platform where it is used. This function can be used
- * change this alignment, if such change is needed. You may check the
+ * to change this alignment, if such change is needed. You may check the
* current alignment by calling silc_stack_get_alignment.
*
* NOTES
***/
SilcUInt32 silc_stack_get_alignment(SilcStack stack);
+/****f* silcutil/SilcStackAPI/silc_stack_purge
+ *
+ * SYNOPSIS
+ *
+ * SilcBool silc_stack_purge(SilcStack stack);
+ *
+ * DESCRIPTION
+ *
+ * Purges the `stack' from extra unused memory. This purges only `stack'
+ * and not its parent if `stack' is a child. This purges only large
+ * allocations. The 1024, 2048, 4096 and 8192 bytes of allocations remain.
+ * Call this multiple times to purge even more. Returns FALSE when there
+ * is no more to purge. This does not purge memory blocks that currently
+ * have allocations. No memory allocations from the stack are lost, so
+ * this is always safe to call.
+ *
+ ***/
+SilcBool silc_stack_purge(SilcStack stack);
+
+/****f* silcutil/SilcStackAPI/silc_stack_set_global
+ *
+ * SYNOPSIS
+ *
+ * void silc_stack_set_global(SilcStack stack);
+ *
+ * DESCRIPTION
+ *
+ * Sets global SilcStack `stack' that can be retrieved at any time
+ * by using silc_stack_get_global. The global stack is global only
+ * to the current thread. Each thread can have their own global stack.
+ * If each thread must have own stack this must be called in each
+ * thread. If the global stack has been set already, new call will
+ * replace the old one.
+ *
+ * This routine is provided only as a convenience function to store
+ * program's or thread's stack in one global place. It is not mandatory
+ * to call this function in order to use SilcStack.
+ *
+ ***/
+void silc_stack_set_global(SilcStack stack);
+
+/****f* silcutil/SilcStackAPI/silc_stack_get_global
+ *
+ * SYNOPSIS
+ *
+ * SilcStack silc_stack_get_global(void);
+ *
+ * DESCRIPTION
+ *
+ * Returns the thread's global stack that was set by calling the
+ * silc_stack_set_global or NULL if global stack has not been set.
+ *
+ ***/
+SilcStack silc_stack_get_global(void);
+
#include "silcstack_i.h"
#endif /* SILCSTACK_H */
projects / silc.git / blobdiff