lv_cache.h

API reference for lv_cache.h

Summary

Functions

private/misc/cache/lv_cache.h:299function

Set the maximum size of the cache. If the current cache size is greater than the new maximum size, the cache's policy will be used to evict entries until the new maximum size is reached. If set to 0, the cache will be disabled.

void lv_cache_set_max_size(lv_cache_t *cache, size_t max_size, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to set the maximum size.
`max_size`	`size_t`	The new maximum size of the cache.
`user_data`	`void *`	A user data pointer that will be passed to the free callback. May be `NULL`.

But this behavior will happen only new entries are added to the cache.

private/misc/cache/lv_cache.h:339function

lv_cache_set_compare_cb

Set the compare callback of the cache.

void lv_cache_set_compare_cb(lv_cache_t *cache, lv_cache_compare_cb_t compare_cb, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to set the compare callback.
`compare_cb`	`lv_cache_compare_cb_t`	The compare callback to set.
`user_data`	`void *`	A user data pointer. May be `NULL`.

private/misc/cache/lv_cache.h:347function

lv_cache_set_create_cb

Set the create callback of the cache.

void lv_cache_set_create_cb(lv_cache_t *cache, lv_cache_create_cb_t alloc_cb, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to set the create callback.
`alloc_cb`	`lv_cache_create_cb_t`	The create callback to set.
`user_data`	`void *`	A user data pointer. May be `NULL`.

private/misc/cache/lv_cache.h:355function

lv_cache_set_free_cb

Set the free callback of the cache.

void lv_cache_set_free_cb(lv_cache_t *cache, lv_cache_free_cb_t free_cb, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to set the free callback.
`free_cb`	`lv_cache_free_cb_t`	The free callback to set.
`user_data`	`void *`	A user data pointer. May be `NULL`.

private/misc/cache/lv_cache.h:362function

lv_cache_set_name

Give a name for a cache object. Only the pointer of the string is saved.

void lv_cache_set_name(lv_cache_t *cache, const char *name)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to set the name.
`name`	`const char *`	The name of the cache.

private/misc/cache/lv_cache.h:307function

lv_cache_get_max_size

Get the maximum size of the cache.

size_t lv_cache_get_max_size(lv_cache_t *cache, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to get the maximum size.
`user_data`	`void *`	A user data pointer that will be passed to the free callback. May be `NULL`.

Returns: size_t — Returns the maximum size of the cache.

private/misc/cache/lv_cache.h:315function

lv_cache_get_size

Get the current size of the cache.

size_t lv_cache_get_size(lv_cache_t *cache, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to get the current size.
`user_data`	`void *`	A user data pointer that will be passed to the free callback. May be `NULL`.

Returns: size_t — Returns the current size of the cache.

private/misc/cache/lv_cache.h:323function

lv_cache_get_free_size

Get the free size of the cache.

size_t lv_cache_get_free_size(lv_cache_t *cache, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to get the free size.
`user_data`	`void *`	A user data pointer that will be passed to the free callback. May be `NULL`.

Returns: size_t — Returns the free size of the cache.

private/misc/cache/lv_cache.h:369function

lv_cache_get_name

Get the name of a cache object.

const char * lv_cache_get_name(lv_cache_t *cache)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to get the name.

Returns: const char * — Returns the name of the cache.

private/misc/cache/lv_cache.h:383function

lv_cache_entry_get_cache

Get the cache instance of a cache entry.

const lv_cache_t * lv_cache_entry_get_cache(const lv_cache_entry_t *entry)

Name	Type	Description
`entry`	`const lv_cache_entry_t *`	The cache entry to get the cache instance of.

Returns: const lv_cache_t * — The pointer to the cache instance of the cache entry.

private/misc/cache/lv_cache.h:201function

lv_cache_create

Create a cache object with the given parameters.

lv_cache_t * lv_cache_create(const lv_cache_class_t *cache_class, size_t node_size, size_t max_size, lv_cache_ops_t ops)

Name	Type	Description
`cache_class`	`const lv_cache_class_t *`	The class of the cache. Currently only support one two builtin classes: - lv_cache_class_lru_rb_count for LRU-based cache with count-based eviction policy. - lv_cache_class_lru_rb_size for LRU-based cache with size-based eviction policy.
`node_size`	`size_t`	The node size is the size of the data stored in the cache..
`max_size`	`size_t`	The max size is the maximum amount of memory or count that the cache can hold. - lv_cache_class_lru_rb_count: max_size is the maximum count of nodes in the cache. - lv_cache_class_lru_rb_size: max_size is the maximum size of the cache in bytes.
`ops`	`lv_cache_ops_t`	A set of operations that can be performed on the cache. See lv_cache_ops_t for details.

Returns: lv_cache_t * — Returns a pointer to the created cache object on success, NULL on error.

private/misc/cache/lv_cache.h:210function

lv_cache_destroy

Destroy a cache object.

void lv_cache_destroy(lv_cache_t *cache, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to destroy.
`user_data`	`void *`	A user data pointer that will be passed to the free callback. May be `NULL`.

private/misc/cache/lv_cache.h:220function

lv_cache_acquire

Acquire a cache entry with the given key. If entry not in cache, it will return NULL (not found). If the entry is found, it's priority will be changed by the cache's policy. And the lv_cache_entry_t::ref_cnt will be incremented.

lv_cache_entry_t * lv_cache_acquire(lv_cache_t *cache, const void *key, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to acquire the entry.
`key`	`const void *`	The key of the entry to acquire.
`user_data`	`void *`	A user data pointer that will be passed to the create callback. May be `NULL`.

Returns: lv_cache_entry_t * — Returns a pointer to the acquired cache entry on success with lv_cache_entry_t::ref_cnt incremented, NULL on error.

private/misc/cache/lv_cache.h:233function

lv_cache_acquire_or_create

Acquire a cache entry with the given key. If the entry is not in the cache, it will create a new entry with the given key. If the entry is found, it's priority will be changed by the cache's policy. And the lv_cache_entry_t::ref_cnt will be incremented. If you want to use this API to simplify the code, you should provide a lv_cache_ops_t::create_cb that creates a new entry with the given key. This API is a combination of lv_cache_acquire() and lv_cache_add(). The effect is the same as calling lv_cache_acquire() and lv_cache_add() separately. And the internal impact on cache is also consistent with these two APIs.

lv_cache_entry_t * lv_cache_acquire_or_create(lv_cache_t *cache, const void *key, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to acquire the entry.
`key`	`const void *`	The key of the entry to acquire or create.
`user_data`	`void *`	A user data pointer that will be passed to the create callback. May be `NULL`.

Returns: lv_cache_entry_t * — Returns a pointer to the acquired or created cache entry on success with lv_cache_entry_t::ref_cnt incremented, NULL on error.

private/misc/cache/lv_cache.h:242function

lv_cache_add

Add a new cache entry with the given key and data. If the cache is full, the cache's policy will be used to evict an entry.

lv_cache_entry_t * lv_cache_add(lv_cache_t *cache, const void *key, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to add the entry.
`key`	`const void *`	The key of the entry to add.
`user_data`	`void *`	A user data pointer that will be passed to the create callback. May be `NULL`.

Returns: lv_cache_entry_t * — Returns a pointer to the added cache entry on success with lv_cache_entry_t::ref_cnt incremented, NULL on error.

private/misc/cache/lv_cache.h:251function

lv_cache_release

Release a cache entry. The lv_cache_entry_t::ref_cnt will be decremented. If the lv_cache_entry_t::ref_cnt is zero, it will issue an error. If the entry passed to this function is the last reference to the data and the entry is marked as invalid, the cache's policy will be used to evict the entry.

void lv_cache_release(lv_cache_t *cache, lv_cache_entry_t *entry, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to release the entry.
`entry`	`lv_cache_entry_t *`	The cache entry pointer to release.
`user_data`	`void *`	A user data pointer that will be passed to the free callback. May be `NULL`.

private/misc/cache/lv_cache.h:261function

lv_cache_reserve

Reserve a certain amount of memory/count in the cache. This function is useful when you want to reserve a certain amount of memory/count in advance, for example, when you know that you will need it later. When the current cache size is max than the reserved size, the function will evict entries until the reserved size is reached.

void lv_cache_reserve(lv_cache_t *cache, uint32_t reserved_size, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to reserve.
`reserved_size`	`uint32_t`	The amount of memory/count to reserve.
`user_data`	`void *`	A user data pointer that will be passed to the free callback. May be `NULL`.

private/misc/cache/lv_cache.h:272function

lv_cache_drop

Drop a cache entry with the given key. If the entry is not in the cache, nothing will happen to it. If the entry is found, it will be removed from the cache and its data will be freed when the last reference to it is released.

void lv_cache_drop(lv_cache_t *cache, const void *key, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to drop the entry.
`key`	`const void *`	The key of the entry to drop.
`user_data`	`void *`	A user data pointer that will be passed to the free callback. May be `NULL`.

The data will not be freed immediately but when the last reference to it is released. But this entry will not be found by lv_cache_acquire(). If you want cache a same key again, you should use lv_cache_add() or lv_cache_acquire_or_create().

private/misc/cache/lv_cache.h:280function

lv_cache_drop_all

Drop all cache entries. All entries will be removed from the cache and their data will be freed when the last reference to them is released.

void lv_cache_drop_all(lv_cache_t *cache, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to drop all entries.
`user_data`	`void *`	A user data pointer that will be passed to the free callback. May be `NULL`.

If some entries are still referenced by other objects, it will issue an error. And this case shouldn't happen in normal cases..

private/misc/cache/lv_cache.h:288function

lv_cache_evict_one

Evict one entry from the cache. The eviction policy will be used to select the entry to evict.

bool lv_cache_evict_one(lv_cache_t *cache, void *user_data)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to evict an entry.
`user_data`	`void *`	A user data pointer that will be passed to the free callback. May be `NULL`.

Returns: bool — Returns true if an entry is evicted, false if no entry is evicted.

private/misc/cache/lv_cache.h:331function

lv_cache_is_enabled

Return true if the cache is enabled. Disabled cache means that when the max_size of the cache is 0. In this case, all cache operations will be no-op.

bool lv_cache_is_enabled(lv_cache_t *cache)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to check if it's disabled.

Returns: bool — Returns true if the cache is enabled, false otherwise.

private/misc/cache/lv_cache.h:376function

lv_cache_iter_create

Create an iterator for the cache object. The iterator is used to iterate over all cache entries.

lv_iter_t * lv_cache_iter_create(lv_cache_t *cache)

Name	Type	Description
`cache`	`lv_cache_t *`	The cache object pointer to create the iterator.

Returns: lv_iter_t * — Returns a pointer to the created iterator on success, NULL on error.

private/misc/cache/lv_cache.h:391function

lv_cache_entry_alloc

Allocate a cache entry.

lv_cache_entry_t * lv_cache_entry_alloc(const uint32_t node_size, const lv_cache_t *cache)

Name	Type	Description
`node_size`	`const uint32_t`	The size of the node in the cache.
`cache`	`const lv_cache_t *`	The cache instance to allocate the cache entry from.

Returns: lv_cache_entry_t * — The pointer to the allocated cache entry.

private/misc/cache/lv_cache.h:399function

lv_cache_entry_init

Initialize a cache entry.

void lv_cache_entry_init(lv_cache_entry_t *entry, const lv_cache_t *cache, const uint32_t node_size)

Name	Type	Description
`entry`	`lv_cache_entry_t *`	The cache entry to initialize.
`cache`	`const lv_cache_t *`	The cache instance to allocate the cache entry from.
`node_size`	`const uint32_t`	The size of the node in the cache.

private/misc/cache/lv_cache.h:405function

lv_cache_entry_delete

Deallocate a cache entry. And the data of the cache entry will be freed.

void lv_cache_entry_delete(lv_cache_entry_t *entry)

Name	Type	Description
`entry`	`lv_cache_entry_t *`	The cache entry to deallocate.

Enums

private/misc/cache/lv_cache.h:35enum

lv_cache_reserve_cond_res_t

The result of the cache reserve condition callback

Name	Description
`LV_CACHE_RESERVE_COND_OK`	The condition is met and no entries need to be evicted
`LV_CACHE_RESERVE_COND_TOO_LARGE`	The condition is not met and the reserve size is too large
`LV_CACHE_RESERVE_COND_NEED_VICTIM`	The condition is not met and a victim is needed to be evicted
`LV_CACHE_RESERVE_COND_ERROR`	An error occurred while checking the condition

Structs

struct

_lv_cache_ops_t

The cache operations struct

Member	Type	Description
`compare_cb`	`lv_cache_compare_cb_t`	Compare function for keys
`create_cb`	`lv_cache_create_cb_t`	Create function for nodes
`free_cb`	`lv_cache_free_cb_t`	Free function for nodes

struct

_lv_cache_t

The cache entry struct

Member	Type	Description
`clz`	`const lv_cache_class_t *`	Cache class. There are two built-in classes: - lv_cache_class_lru_rb_count for LRU-based cache with count-based eviction policy. - lv_cache_class_lru_rb_size for LRU-based cache with size-based eviction policy.
`node_size`	`uint32_t`	Size of a node
`max_size`	`uint32_t`	Maximum size of the cache
`size`	`uint32_t`	Current size of the cache
`ops`	`lv_cache_ops_t`	Cache operations struct `_lv_cache_ops_t`
`lock`	`lv_mutex_t`	Cache lock used to protect the cache in multithreading environments
`name`	`const char *`	Name of the cache

struct

_lv_cache_class_t

Cache class struct for building custom cache classes

Examples:

lv_cache_class_lru_rb_count for LRU-based cache with count-based eviction policy.
lv_cache_class_lru_rb_size for LRU-based cache with size-based eviction policy.

Member	Type	Description
`alloc_cb`	`lv_cache_alloc_cb_t`	The allocation function for cache entries
`init_cb`	`lv_cache_init_cb_t`	The initialization function for cache entries
`destroy_cb`	`lv_cache_destroy_cb_t`	The destruction function for cache entries
`get_cb`	`lv_cache_get_cb_t`	The get function for cache entries
`add_cb`	`lv_cache_add_cb_t`	The add function for cache entries
`remove_cb`	`lv_cache_remove_cb_t`	The remove function for cache entries
`drop_cb`	`lv_cache_drop_cb_t`	The drop function for cache entries
`drop_all_cb`	`lv_cache_drop_all_cb_t`	The drop all function for cache entries
`get_victim_cb`	`lv_cache_get_victim_cb`	The get victim function for cache entries
`reserve_cond_cb`	`lv_cache_reserve_cond_cb`	The reserve condition function for cache entries
`iter_create_cb`	`lv_cache_iter_create_cb`	The iterator creation function for cache entries

struct

_lv_cache_slot_size_t

Cache entry slot struct

To add new fields to the cache entry, add them to a new struct and add it to the first field of the cache data struct. And this one is a size slot for the cache entry.

Member	Type	Description
`size`	`size_t`

Typedefs

private/misc/cache/lv_cache.h:29typedef

lv_cache_entry_t

typedef struct _lv_cache_entry_t lv_cache_entry_t

Used by 20 functions

lv_vg_lite_stroke_get_path — param cache_entry
lv_vg_lite_stroke_drop — param cache_entry
lv_cache_release — param entry
lv_cache_entry_get_cache — param entry
lv_cache_entry_init — param entry
lv_cache_entry_delete — param entry
lv_cache_entry_get_ref — param entry
lv_cache_entry_get_node_size — param entry
lv_cache_entry_is_invalid — param entry
lv_cache_entry_get_data — param entry
lv_cache_entry_reset_ref — param entry
lv_cache_entry_inc_ref — param entry
lv_cache_entry_dec_ref — param entry
lv_cache_entry_set_node_size — param entry
lv_cache_entry_set_cache — param entry
lv_cache_entry_acquire_data — param entry
lv_cache_entry_release_data — param entry
lv_cache_entry_set_flag — param entry
lv_cache_entry_remove_flag — param entry
lv_cache_entry_has_flag — param entry

private/misc/cache/lv_cache.h:30typedef

lv_cache_t

typedef struct _lv_cache_t lv_cache_t

Used by 23 functions

lv_cache_destroy — param cache
lv_cache_acquire — param cache
lv_cache_acquire_or_create — param cache
lv_cache_add — param cache
lv_cache_release — param cache
lv_cache_reserve — param cache
lv_cache_drop — param cache
lv_cache_drop_all — param cache
lv_cache_evict_one — param cache
lv_cache_set_max_size — param cache
lv_cache_get_max_size — param cache
lv_cache_get_size — param cache
lv_cache_get_free_size — param cache
lv_cache_is_enabled — param cache
lv_cache_set_compare_cb — param cache
lv_cache_set_create_cb — param cache
lv_cache_set_free_cb — param cache
lv_cache_set_name — param cache
lv_cache_get_name — param cache
lv_cache_iter_create — param cache
lv_cache_entry_alloc — param cache
lv_cache_entry_init — param cache
lv_cache_entry_set_cache — param cache

private/misc/cache/lv_cache.h:43typedef

lv_cache_ops_t

typedef struct _lv_cache_ops_t lv_cache_ops_t

Used by 1 function

lv_cache_create — param ops

private/misc/cache/lv_cache.h:44typedef

lv_cache_class_t

typedef struct _lv_cache_class_t lv_cache_class_t

Used by 1 function

lv_cache_create — param cache_class

private/misc/cache/lv_cache.h:46typedef

lv_cache_compare_res_t

typedef int32_t lv_cache_compare_res_t

private/misc/cache/lv_cache.h:47typedef

lv_cache_create_cb_t

typedef bool(* lv_cache_create_cb_t) (void *node, void *user_data)

Used by 1 function

lv_cache_set_create_cb — param alloc_cb

private/misc/cache/lv_cache.h:48typedef

lv_cache_free_cb_t

typedef void(* lv_cache_free_cb_t) (void *node, void *user_data)

Used by 1 function

lv_cache_set_free_cb — param free_cb

private/misc/cache/lv_cache.h:49typedef

lv_cache_compare_cb_t

typedef lv_cache_compare_res_t(* lv_cache_compare_cb_t) (const void *a, const void *b)

Used by 1 function

lv_cache_set_compare_cb — param compare_cb

private/misc/cache/lv_cache.h:55typedef

lv_cache_alloc_cb_t

typedef void *(* lv_cache_alloc_cb_t) (void)

The cache instance allocation function, used by the cache class to allocate memory for cache instances.

private/misc/cache/lv_cache.h:61typedef

lv_cache_init_cb_t

typedef bool(* lv_cache_init_cb_t) (lv_cache_t *cache)

The cache instance initialization function, used by the cache class to initialize the cache instance.

private/misc/cache/lv_cache.h:66typedef

lv_cache_destroy_cb_t

typedef void(* lv_cache_destroy_cb_t) (lv_cache_t *cache, void *user_data)

The cache instance destruction function, used by the cache class to destroy the cache instance.

private/misc/cache/lv_cache.h:72typedef

lv_cache_get_cb_t

typedef lv_cache_entry_t *(* lv_cache_get_cb_t) (lv_cache_t *cache, const void *key, void *user_data)

The cache get function, used by the cache class to get a cache entry by its key.

private/misc/cache/lv_cache.h:79typedef

lv_cache_add_cb_t

typedef lv_cache_entry_t *(* lv_cache_add_cb_t) (lv_cache_t *cache, const void *key, void *user_data)

The cache add function, used by the cache class to add a cache entry with a given key. This function only cares about how to add the entry, it doesn't check if the entry already exists and doesn't care about is it a victim or not.

private/misc/cache/lv_cache.h:85typedef

lv_cache_remove_cb_t

typedef void(* lv_cache_remove_cb_t) (lv_cache_t *cache, lv_cache_entry_t *entry, void *user_data)

The cache remove function, used by the cache class to remove a cache entry from the cache but doesn't free the memory.. This function only cares about how to remove the entry, it doesn't care about is it a victim or not.

private/misc/cache/lv_cache.h:90typedef

lv_cache_drop_cb_t

typedef void(* lv_cache_drop_cb_t) (lv_cache_t *cache, const void *key, void *user_data)

The cache drop function, used by the cache class to remove a cache entry from the cache and free the memory.

private/misc/cache/lv_cache.h:95typedef

lv_cache_drop_all_cb_t

typedef void(* lv_cache_drop_all_cb_t) (lv_cache_t *cache, void *user_data)

The cache drop all function, used by the cache class to remove all cache entries from the cache and free the memory.

private/misc/cache/lv_cache.h:100typedef

lv_cache_get_victim_cb

typedef lv_cache_entry_t *(* lv_cache_get_victim_cb) (lv_cache_t *cache, void *user_data)

The cache get victim function, used by the cache class to get a victim entry to be evicted.

private/misc/cache/lv_cache.h:106typedef

lv_cache_reserve_cond_cb

typedef lv_cache_reserve_cond_res_t(* lv_cache_reserve_cond_cb) (lv_cache_t *cache, const void *key, size_t size, void *user_data)

The cache reserve condition function, used by the cache class to check if a new entry can be added to the cache without exceeding its maximum size. See lv_cache_reserve_cond_res_t for the possible results.

private/misc/cache/lv_cache.h:113typedef

lv_cache_iter_create_cb

typedef lv_iter_t *(* lv_cache_iter_create_cb) (lv_cache_t *cache)

The cache iterator creation function, used by the cache class to create an iterator for the cache.

private/misc/cache/lv_cache.h:173typedef

lv_cache_slot_size_t

typedef struct _lv_cache_slot_size_t lv_cache_slot_size_t

Dependencies

Indirect dependencies

lv_cache.h

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