Wed Oct 28 15:49:03 2009

Asterisk developer's documentation


linkedlists.h File Reference

A set of macros to manage forward-linked lists. More...

#include "asterisk/lock.h"

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Defines

#define AST_LIST_APPEND_LIST(head, list, field)
 Appends a whole list to the tail of a list.
#define AST_LIST_EMPTY(head)   (AST_LIST_FIRST(head) == NULL)
 Checks whether the specified list contains any entries.
#define AST_LIST_ENTRY(type)
 Declare a forward link structure inside a list entry.
#define AST_LIST_FIRST(head)   ((head)->first)
 Returns the first entry contained in a list.
#define AST_LIST_HEAD(name, type)
 Defines a structure to be used to hold a list of specified type.
#define AST_LIST_HEAD_DESTROY(head)
 Destroys a list head structure.
#define AST_LIST_HEAD_INIT(head)
 Initializes a list head structure.
#define AST_LIST_HEAD_INIT_NOLOCK(head)
 Initializes a list head structure.
#define AST_LIST_HEAD_INIT_VALUE
 Defines initial values for a declaration of AST_LIST_HEAD.
#define AST_LIST_HEAD_NOLOCK(name, type)
 Defines a structure to be used to hold a list of specified type (with no lock).
#define AST_LIST_HEAD_NOLOCK_INIT_VALUE
 Defines initial values for a declaration of AST_LIST_HEAD_NOLOCK.
#define AST_LIST_HEAD_NOLOCK_STATIC(name, type)
 Defines a structure to be used to hold a list of specified type, statically initialized.
#define AST_LIST_HEAD_SET(head, entry)
 Initializes a list head structure with a specified first entry.
#define AST_LIST_HEAD_SET_NOLOCK(head, entry)
 Initializes a list head structure with a specified first entry.
#define AST_LIST_HEAD_STATIC(name, type)
 Defines a structure to be used to hold a list of specified type, statically initialized.
#define AST_LIST_INSERT_AFTER(head, listelm, elm, field)
 Inserts a list entry after a given entry.
#define AST_LIST_INSERT_HEAD(head, elm, field)
 Inserts a list entry at the head of a list.
#define AST_LIST_INSERT_TAIL(head, elm, field)
 Appends a list entry to the tail of a list.
#define AST_LIST_LAST(head)   ((head)->last)
 Returns the last entry contained in a list.
#define AST_LIST_LOCK(head)   ast_mutex_lock(&(head)->lock)
 Attempts to lock a list.
#define AST_LIST_NEXT(elm, field)   ((elm)->field.next)
 Returns the next entry in the list after the given entry.
#define AST_LIST_REMOVE(head, elm, field)
 Removes a specific entry from a list.
#define AST_LIST_REMOVE_CURRENT(head, field)
 Removes the current entry from a list during a traversal.
#define AST_LIST_REMOVE_HEAD(head, field)
 Removes and returns the head entry from a list.
#define AST_LIST_TRAVERSE(head, var, field)   for((var) = (head)->first; (var); (var) = (var)->field.next)
 Loops over (traverses) the entries in a list.
#define AST_LIST_TRAVERSE_SAFE_BEGIN(head, var, field)
 Loops safely over (traverses) the entries in a list.
#define AST_LIST_TRAVERSE_SAFE_END   }
 Closes a safe loop traversal block.
#define AST_LIST_UNLOCK(head)   ast_mutex_unlock(&(head)->lock)
 Attempts to unlock a list.


Detailed Description

A set of macros to manage forward-linked lists.

Definition in file linkedlists.h.


Define Documentation

#define AST_LIST_APPEND_LIST ( head,
list,
field   ) 

Appends a whole list to the tail of a list.

Parameters:
head This is a pointer to the list head structure
list This is a pointer to the list to be appended.
field This is the name of the field (declared using AST_LIST_ENTRY()) used to link entries of this list together.

Definition at line 439 of file linkedlists.h.

Referenced by clone_variables().

#define AST_LIST_EMPTY ( head   )     (AST_LIST_FIRST(head) == NULL)

Checks whether the specified list contains any entries.

Parameters:
head This is a pointer to the list head structure
Returns non-zero if the list has entries, zero if not.

Definition at line 230 of file linkedlists.h.

Referenced by app_exec(), ast_cdr_free_vars(), dundi_lookup_local(), get_destination(), handle_showfeatures(), loopback_helper(), register_verify(), reload_config(), sip_show_domains(), and sip_show_settings().

#define AST_LIST_ENTRY ( type   ) 

Value:

struct {                      \
   struct type *next;                  \
}
Declare a forward link structure inside a list entry.

Parameters:
type This is the type of each list entry.
This macro declares a structure to be used to link list entries together. It must be used inside the definition of the structure named in type, as follows:

  struct list_entry {
   ...
   AST_LIST_ENTRY(list_entry) list;
  }

The field name list here is arbitrary, and can be anything you wish.

Definition at line 199 of file linkedlists.h.

#define AST_LIST_FIRST ( head   )     ((head)->first)

Returns the first entry contained in a list.

Parameters:
head This is a pointer to the list head structure

Definition at line 208 of file linkedlists.h.

Referenced by __ast_device_state_changed_literal(), ast_add_extension2(), ast_app_group_list_head(), clone_variables(), conf_cmd(), gen_readframe(), and spy_cleanup().

#define AST_LIST_HEAD ( name,
type   ) 

Value:

struct name {                       \
   struct type *first;                 \
   struct type *last;                  \
   ast_mutex_t lock;                \
}
Defines a structure to be used to hold a list of specified type.

Parameters:
name This will be the name of the defined structure.
type This is the type of each list entry.
This macro creates a structure definition that can be used to hold a list of the entries of type type. It does not actually declare (allocate) a structure; to do that, either follow this macro with the desired name of the instance you wish to declare, or use the specified name to declare instances elsewhere.

Example usage:

  static AST_LIST_HEAD(entry_list, entry) entries;

This would define struct entry_list, and declare an instance of it named entries, all intended to hold a list of type struct entry.

Definition at line 71 of file linkedlists.h.

#define AST_LIST_HEAD_DESTROY ( head   ) 

Value:

{              \
   (head)->first = NULL;                  \
   (head)->last = NULL;                \
   ast_mutex_destroy(&(head)->lock);            \
}
Destroys a list head structure.

Parameters:
head This is a pointer to the list head structure
This macro destroys a list head structure by setting the head entry to NULL (empty list) and destroying the embedded lock. It does not free the structure from memory.

Definition at line 362 of file linkedlists.h.

#define AST_LIST_HEAD_INIT ( head   ) 

Value:

{              \
   (head)->first = NULL;                  \
   (head)->last = NULL;                \
   ast_mutex_init(&(head)->lock);               \
}
Initializes a list head structure.

Parameters:
head This is a pointer to the list head structure
This macro initializes a list head structure by setting the head entry to NULL (empty list) and recreating the embedded lock.

Definition at line 348 of file linkedlists.h.

Referenced by app_exec(), and ast_merge_contexts_and_delete().

#define AST_LIST_HEAD_INIT_NOLOCK ( head   ) 

Value:

{           \
   (head)->first = NULL;                  \
   (head)->last = NULL;                \
}
Initializes a list head structure.

Parameters:
head This is a pointer to the list head structure
This macro initializes a list head structure by setting the head entry to NULL (empty list). There is no embedded lock handling with this macro.

Definition at line 376 of file linkedlists.h.

Referenced by ast_channel_alloc(), ast_channel_spy_add(), clone_variables(), dundi_lookup_local(), load_pbx(), and loopback_helper().

#define AST_LIST_HEAD_INIT_VALUE

Value:

{     \
   .first = NULL,             \
   .last = NULL,              \
   .lock = AST_MUTEX_INIT_VALUE,       \
   }
Defines initial values for a declaration of AST_LIST_HEAD.

Definition at line 106 of file linkedlists.h.

#define AST_LIST_HEAD_NOLOCK ( name,
type   ) 

Value:

struct name {                       \
   struct type *first;                 \
   struct type *last;                  \
}
Defines a structure to be used to hold a list of specified type (with no lock).

Parameters:
name This will be the name of the defined structure.
type This is the type of each list entry.
This macro creates a structure definition that can be used to hold a list of the entries of type type. It does not actually declare (allocate) a structure; to do that, either follow this macro with the desired name of the instance you wish to declare, or use the specified name to declare instances elsewhere.

Example usage:

  static AST_LIST_HEAD_NOLOCK(entry_list, entry) entries;

This would define struct entry_list, and declare an instance of it named entries, all intended to hold a list of type struct entry.

Definition at line 97 of file linkedlists.h.

#define AST_LIST_HEAD_NOLOCK_INIT_VALUE

Value:

{  \
   .first = NULL,             \
   .last = NULL,              \
   }
Defines initial values for a declaration of AST_LIST_HEAD_NOLOCK.

Definition at line 115 of file linkedlists.h.

#define AST_LIST_HEAD_NOLOCK_STATIC ( name,
type   ) 

Value:

struct name {                       \
   struct type *first;                 \
   struct type *last;                  \
} name = AST_LIST_HEAD_NOLOCK_INIT_VALUE
Defines a structure to be used to hold a list of specified type, statically initialized.

This is the same as AST_LIST_HEAD_STATIC, except without the lock included.

Definition at line 149 of file linkedlists.h.

#define AST_LIST_HEAD_SET ( head,
entry   ) 

Value:

do {           \
   (head)->first = (entry);               \
   (head)->last = (entry);                \
   ast_mutex_init(&(head)->lock);               \
} while (0)
Initializes a list head structure with a specified first entry.

Parameters:
head This is a pointer to the list head structure
entry pointer to the list entry that will become the head of the list
This macro initializes a list head structure by setting the head entry to the supplied value and recreating the embedded lock.

Definition at line 163 of file linkedlists.h.

#define AST_LIST_HEAD_SET_NOLOCK ( head,
entry   ) 

Value:

do {        \
   (head)->first = (entry);               \
   (head)->last = (entry);                \
} while (0)
Initializes a list head structure with a specified first entry.

Parameters:
head This is a pointer to the list head structure
entry pointer to the list entry that will become the head of the list
This macro initializes a list head structure by setting the head entry to the supplied value.

Definition at line 177 of file linkedlists.h.

#define AST_LIST_HEAD_STATIC ( name,
type   ) 

Value:

struct name {                       \
   struct type *first;                 \
   struct type *last;                  \
   ast_mutex_t lock;                \
} name = AST_LIST_HEAD_INIT_VALUE
Defines a structure to be used to hold a list of specified type, statically initialized.

Parameters:
name This will be the name of the defined structure.
type This is the type of each list entry.
This macro creates a structure definition that can be used to hold a list of the entries of type type, and allocates an instance of it, initialized to be empty.

Example usage:

  static AST_LIST_HEAD_STATIC(entry_list, entry);

This would define struct entry_list, intended to hold a list of type struct entry.

Definition at line 137 of file linkedlists.h.

#define AST_LIST_INSERT_AFTER ( head,
listelm,
elm,
field   ) 

Inserts a list entry after a given entry.

Parameters:
head This is a pointer to the list head structure
listelm This is a pointer to the entry after which the new entry should be inserted.
elm This is a pointer to the entry to be inserted.
field This is the name of the field (declared using AST_LIST_ENTRY()) used to link entries of this list together.

Definition at line 390 of file linkedlists.h.

#define AST_LIST_INSERT_HEAD ( head,
elm,
field   ) 

Inserts a list entry at the head of a list.

Parameters:
head This is a pointer to the list head structure
elm This is a pointer to the entry to be inserted.
field This is the name of the field (declared using AST_LIST_ENTRY()) used to link entries of this list together.

Definition at line 404 of file linkedlists.h.

Referenced by __ao2_link(), add_identifier(), add_to_interfaces(), ast_cdr_copy_vars(), ast_cdr_register(), ast_cdr_setvar(), ast_channel_spy_add(), ast_devstate_add(), ast_dnsmgr_get(), ast_merge_contexts_and_delete(), ast_register_feature(), ast_register_file_version(), build_conf(), dundi_lookup_local(), loopback_helper(), pbx_builtin_pushvar_helper(), pbx_builtin_setvar_helper(), and register_translator().

#define AST_LIST_INSERT_TAIL ( head,
elm,
field   ) 

Appends a list entry to the tail of a list.

Parameters:
head This is a pointer to the list head structure
elm This is a pointer to the entry to be appended.
field This is the name of the field (declared using AST_LIST_ENTRY()) used to link entries of this list together.
Note: The link field in the appended entry is not modified, so if it is actually the head of a list itself, the entire list will be appended temporarily (until the next AST_LIST_INSERT_TAIL is performed).

Definition at line 422 of file linkedlists.h.

Referenced by __ao2_link(), __ast_device_state_changed_literal(), add_sip_domain(), app_exec(), ast_app_group_set_channel(), ast_channel_inherit_variables(), ast_channel_spy_add(), clone_variables(), conf_run(), gen_readframe(), and local_call().

#define AST_LIST_LAST ( head   )     ((head)->last)

Returns the last entry contained in a list.

Parameters:
head This is a pointer to the list tail structure

Definition at line 214 of file linkedlists.h.

Referenced by admin_exec(), and conf_run().

#define AST_LIST_LOCK ( head   )     ast_mutex_lock(&(head)->lock)

#define AST_LIST_NEXT ( elm,
field   )     ((elm)->field.next)

Returns the next entry in the list after the given entry.

Parameters:
elm This is a pointer to the current entry.
field This is the name of the field (declared using AST_LIST_ENTRY()) used to link entries of this list together.

Definition at line 222 of file linkedlists.h.

Referenced by ao2_iterator_next(), group_function_read(), group_list_function_read(), and group_show_channels().

#define AST_LIST_REMOVE ( head,
elm,
field   ) 

Removes a specific entry from a list.

Parameters:
head This is a pointer to the list head structure
elm This is a pointer to the entry to be removed.
field This is the name of the field (declared using AST_LIST_ENTRY()) used to link entries of this list together.
Warning:
The removed entry is not freed nor modified in any way.

Definition at line 477 of file linkedlists.h.

Referenced by ast_channel_spy_remove(), ast_dnsmgr_release(), ast_unregister_feature(), conf_run(), del_identifier(), and pbx_builtin_setvar_helper().

#define AST_LIST_REMOVE_CURRENT ( head,
field   ) 

Removes the current entry from a list during a traversal.

Parameters:
head This is a pointer to the list head structure
field This is the name of the field (declared using AST_LIST_ENTRY()) used to link entries of this list together.
Note:
This macro can only be used inside an AST_LIST_TRAVERSE_SAFE_BEGIN() block; it is used to unlink the current entry from the list without affecting the list traversal (and without having to re-traverse the list to modify the previous entry, if any).

Definition at line 327 of file linkedlists.h.

Referenced by ao2_callback(), ast_app_group_discard(), ast_app_group_set_channel(), ast_cdr_setvar(), ast_cdr_unregister(), ast_channel_spy_stop_by_type(), ast_devstate_del(), ast_unregister_file_version(), conf_free(), detach_spies(), drop_translator(), and remove_from_interfaces().

#define AST_LIST_REMOVE_HEAD ( head,
field   ) 

Removes and returns the head entry from a list.

Parameters:
head This is a pointer to the list head structure
field This is the name of the field (declared using AST_LIST_ENTRY()) used to link entries of this list together.
Removes the head entry from the list, and returns a pointer to it. This macro is safe to call on an empty list.

Definition at line 458 of file linkedlists.h.

Referenced by app_exec(), ast_cdr_free_vars(), ast_channel_free(), ast_merge_contexts_and_delete(), ast_unregister_features(), clear_and_free_interfaces(), clear_sip_domains(), do_devstate_changes(), dundi_lookup_local(), gen_nextfile(), loopback_helper(), pbx_builtin_clear_globals(), and unregister_translators().

#define AST_LIST_TRAVERSE ( head,
var,
field   )     for((var) = (head)->first; (var); (var) = (var)->field.next)

Loops over (traverses) the entries in a list.

Parameters:
head This is a pointer to the list head structure
var This is the name of the variable that will hold a pointer to the current list entry on each iteration. It must be declared before calling this macro.
field This is the name of the field (declared using AST_LIST_ENTRY()) used to link entries of this list together.
This macro is use to loop over (traverse) the entries in a list. It uses a for loop, and supplies the enclosed code with a pointer to each list entry as it loops. It is typically used as follows:
  static AST_LIST_HEAD(entry_list, list_entry) entries;
  ...
  struct list_entry {
   ...
   AST_LIST_ENTRY(list_entry) list;
  }
  ...
  struct list_entry *current;
  ...
  AST_LIST_TRAVERSE(&entries, current, list) {
     (do something with current here)
  }
Warning:
If you modify the forward-link pointer contained in the current entry while inside the loop, the behavior will be unpredictable. At a minimum, the following macros will modify the forward-link pointer, and should not be used inside AST_LIST_TRAVERSE() against the entry pointed to by the current pointer without careful consideration of their consequences:

Definition at line 268 of file linkedlists.h.

Referenced by add_identifier(), add_to_interfaces(), admin_exec(), ao2_iterator_next(), aPGSQL_fetch(), ast_app_group_get_count(), ast_app_group_match_get_count(), ast_app_group_update(), ast_cdr_copy_vars(), ast_cdr_getvar_internal(), ast_cdr_register(), ast_cdr_serialize_variables(), ast_channel_inherit_variables(), ast_do_masquerade(), build_conf(), changethread(), check_sip_domain(), clone_variables(), complete_confcmd(), complete_show_version_files(), conf_cmd(), conf_exec(), del_identifier(), do_state_change(), feature_exec_app(), find_conf(), find_feature(), find_identifier(), find_user(), handle_cli_status(), handle_show_version_files(), handle_showfeatures(), launch_page(), local_call(), mgcp_call(), pbx_builtin_getvar_helper(), pbx_builtin_serialize_variables(), pbx_builtin_setvar_helper(), pbx_retrieve_variable(), post_cdr(), queue_frame_to_spies(), refresh_list(), sip_call(), sip_show_domains(), and transmit_invite().

#define AST_LIST_TRAVERSE_SAFE_BEGIN ( head,
var,
field   ) 

Loops safely over (traverses) the entries in a list.

Parameters:
head This is a pointer to the list head structure
var This is the name of the variable that will hold a pointer to the current list entry on each iteration. It must be declared before calling this macro.
field This is the name of the field (declared using AST_LIST_ENTRY()) used to link entries of this list together.
This macro is used to safely loop over (traverse) the entries in a list. It uses a for loop, and supplies the enclosed code with a pointer to each list entry as it loops. It is typically used as follows:

  static AST_LIST_HEAD(entry_list, list_entry) entries;
  ...
  struct list_entry {
   ...
   AST_LIST_ENTRY(list_entry) list;
  }
  ...
  struct list_entry *current;
  ...
  AST_LIST_TRAVERSE_SAFE_BEGIN(&entries, current, list) {
     (do something with current here)
  }
  AST_LIST_TRAVERSE_SAFE_END;

It differs from AST_LIST_TRAVERSE() in that the code inside the loop can modify (or even free, after calling AST_LIST_REMOVE_CURRENT()) the entry pointed to by the current pointer without affecting the loop traversal.

Definition at line 304 of file linkedlists.h.

Referenced by ao2_callback(), ast_app_group_discard(), ast_app_group_set_channel(), ast_cdr_setvar(), ast_cdr_unregister(), ast_channel_spy_stop_by_type(), ast_devstate_del(), ast_unregister_file_version(), conf_free(), detach_spies(), drop_translator(), and remove_from_interfaces().

#define AST_LIST_TRAVERSE_SAFE_END   }

#define AST_LIST_UNLOCK ( head   )     ast_mutex_unlock(&(head)->lock)


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