Apache Portable Runtime
Data Structures | Defines | Typedefs | Enumerations | Functions | Variables
Bucket Brigades
Apache Portability Runtime library

Data Structures

struct  apr_bucket_type_t
struct  apr_bucket
struct  apr_bucket_brigade
struct  apr_bucket_refcount
struct  apr_bucket_heap
struct  apr_bucket_pool
struct  apr_bucket_mmap
struct  apr_bucket_file
union  apr_bucket_structs

Defines

#define APR_BUCKET_BUFF_SIZE   8000
#define APR_BRIGADE_CHECK_CONSISTENCY(b)
#define APR_BUCKET_CHECK_CONSISTENCY(e)
#define APR_BRIGADE_SENTINEL(b)   APR_RING_SENTINEL(&(b)->list, apr_bucket, link)
#define APR_BRIGADE_EMPTY(b)   APR_RING_EMPTY(&(b)->list, apr_bucket, link)
#define APR_BRIGADE_FIRST(b)   APR_RING_FIRST(&(b)->list)
#define APR_BRIGADE_LAST(b)   APR_RING_LAST(&(b)->list)
#define APR_BRIGADE_INSERT_HEAD(b, e)
#define APR_BRIGADE_INSERT_TAIL(b, e)
#define APR_BRIGADE_CONCAT(a, b)
#define APR_BRIGADE_PREPEND(a, b)
#define APR_BUCKET_INSERT_BEFORE(a, b)
#define APR_BUCKET_INSERT_AFTER(a, b)
#define APR_BUCKET_NEXT(e)   APR_RING_NEXT((e), link)
#define APR_BUCKET_PREV(e)   APR_RING_PREV((e), link)
#define APR_BUCKET_REMOVE(e)   APR_RING_REMOVE((e), link)
#define APR_BUCKET_INIT(e)   APR_RING_ELEM_INIT((e), link)
#define APR_BUCKET_IS_METADATA(e)   ((e)->type->is_metadata)
#define APR_BUCKET_IS_FLUSH(e)   ((e)->type == &apr_bucket_type_flush)
#define APR_BUCKET_IS_EOS(e)   ((e)->type == &apr_bucket_type_eos)
#define APR_BUCKET_IS_FILE(e)   ((e)->type == &apr_bucket_type_file)
#define APR_BUCKET_IS_PIPE(e)   ((e)->type == &apr_bucket_type_pipe)
#define APR_BUCKET_IS_SOCKET(e)   ((e)->type == &apr_bucket_type_socket)
#define APR_BUCKET_IS_HEAP(e)   ((e)->type == &apr_bucket_type_heap)
#define APR_BUCKET_IS_TRANSIENT(e)   ((e)->type == &apr_bucket_type_transient)
#define APR_BUCKET_IS_IMMORTAL(e)   ((e)->type == &apr_bucket_type_immortal)
#define APR_BUCKET_IS_MMAP(e)   ((e)->type == &apr_bucket_type_mmap)
#define APR_BUCKET_IS_POOL(e)   ((e)->type == &apr_bucket_type_pool)
#define APR_BUCKET_ALLOC_SIZE   APR_ALIGN_DEFAULT(2*sizeof(apr_bucket_structs))
#define apr_bucket_destroy(e)
#define apr_bucket_delete(e)
#define apr_bucket_read(e, str, len, block)   (e)->type->read(e, str, len, block)
#define apr_bucket_setaside(e, p)   (e)->type->setaside(e,p)
#define apr_bucket_split(e, point)   (e)->type->split(e, point)
#define apr_bucket_copy(e, c)   (e)->type->copy(e, c)

Typedefs

typedef struct apr_bucket_brigade apr_bucket_brigade
typedef struct apr_bucket apr_bucket
typedef struct apr_bucket_alloc_t apr_bucket_alloc_t
typedef struct apr_bucket_type_t apr_bucket_type_t
typedef apr_status_t(* apr_brigade_flush )(apr_bucket_brigade *bb, void *ctx)
typedef struct apr_bucket_refcount apr_bucket_refcount
typedef struct apr_bucket_heap apr_bucket_heap
typedef struct apr_bucket_pool apr_bucket_pool
typedef struct apr_bucket_mmap apr_bucket_mmap
typedef struct apr_bucket_file apr_bucket_file
typedef union apr_bucket_structs apr_bucket_structs

Enumerations

enum  apr_read_type_e { APR_BLOCK_READ, APR_NONBLOCK_READ }

Functions

apr_bucket_brigadeapr_brigade_create (apr_pool_t *p, apr_bucket_alloc_t *list)
apr_status_t apr_brigade_destroy (apr_bucket_brigade *b)
apr_status_t apr_brigade_cleanup (void *data)
apr_bucket_brigadeapr_brigade_split_ex (apr_bucket_brigade *b, apr_bucket *e, apr_bucket_brigade *a)
apr_bucket_brigadeapr_brigade_split (apr_bucket_brigade *b, apr_bucket *e)
apr_status_t apr_brigade_partition (apr_bucket_brigade *b, apr_off_t point, apr_bucket **after_point)
apr_status_t apr_brigade_length (apr_bucket_brigade *bb, int read_all, apr_off_t *length)
apr_status_t apr_brigade_flatten (apr_bucket_brigade *bb, char *c, apr_size_t *len)
apr_status_t apr_brigade_pflatten (apr_bucket_brigade *bb, char **c, apr_size_t *len, apr_pool_t *pool)
apr_status_t apr_brigade_split_line (apr_bucket_brigade *bbOut, apr_bucket_brigade *bbIn, apr_read_type_e block, apr_off_t maxbytes)
apr_status_t apr_brigade_to_iovec (apr_bucket_brigade *b, struct iovec *vec, int *nvec)
apr_status_t apr_brigade_vputstrs (apr_bucket_brigade *b, apr_brigade_flush flush, void *ctx, va_list va)
apr_status_t apr_brigade_write (apr_bucket_brigade *b, apr_brigade_flush flush, void *ctx, const char *str, apr_size_t nbyte)
apr_status_t apr_brigade_writev (apr_bucket_brigade *b, apr_brigade_flush flush, void *ctx, const struct iovec *vec, apr_size_t nvec)
apr_status_t apr_brigade_puts (apr_bucket_brigade *bb, apr_brigade_flush flush, void *ctx, const char *str)
apr_status_t apr_brigade_putc (apr_bucket_brigade *b, apr_brigade_flush flush, void *ctx, const char c)
apr_status_t apr_brigade_putstrs (apr_bucket_brigade *b, apr_brigade_flush flush, void *ctx,...)
apr_status_t apr_brigade_printf (apr_bucket_brigade *b, apr_brigade_flush flush, void *ctx, const char *fmt,...)
apr_status_t apr_brigade_vprintf (apr_bucket_brigade *b, apr_brigade_flush flush, void *ctx, const char *fmt, va_list va)
apr_bucketapr_brigade_insert_file (apr_bucket_brigade *bb, apr_file_t *f, apr_off_t start, apr_off_t len, apr_pool_t *p)
apr_bucket_alloc_tapr_bucket_alloc_create (apr_pool_t *p)
apr_bucket_alloc_tapr_bucket_alloc_create_ex (apr_allocator_t *allocator)
void apr_bucket_alloc_destroy (apr_bucket_alloc_t *list)
void * apr_bucket_alloc (apr_size_t size, apr_bucket_alloc_t *list)
void apr_bucket_free (void *block)
apr_status_t apr_bucket_setaside_noop (apr_bucket *data, apr_pool_t *pool)
apr_status_t apr_bucket_setaside_notimpl (apr_bucket *data, apr_pool_t *pool)
apr_status_t apr_bucket_split_notimpl (apr_bucket *data, apr_size_t point)
apr_status_t apr_bucket_copy_notimpl (apr_bucket *e, apr_bucket **c)
void apr_bucket_destroy_noop (void *data)
apr_status_t apr_bucket_simple_split (apr_bucket *b, apr_size_t point)
apr_status_t apr_bucket_simple_copy (apr_bucket *a, apr_bucket **b)
apr_bucketapr_bucket_shared_make (apr_bucket *b, void *data, apr_off_t start, apr_size_t length)
int apr_bucket_shared_destroy (void *data)
apr_status_t apr_bucket_shared_split (apr_bucket *b, apr_size_t point)
apr_status_t apr_bucket_shared_copy (apr_bucket *a, apr_bucket **b)
apr_bucketapr_bucket_eos_create (apr_bucket_alloc_t *list)
apr_bucketapr_bucket_eos_make (apr_bucket *b)
apr_bucketapr_bucket_flush_create (apr_bucket_alloc_t *list)
apr_bucketapr_bucket_flush_make (apr_bucket *b)
apr_bucketapr_bucket_immortal_create (const char *buf, apr_size_t nbyte, apr_bucket_alloc_t *list)
apr_bucketapr_bucket_immortal_make (apr_bucket *b, const char *buf, apr_size_t nbyte)
apr_bucketapr_bucket_transient_create (const char *buf, apr_size_t nbyte, apr_bucket_alloc_t *list)
apr_bucketapr_bucket_transient_make (apr_bucket *b, const char *buf, apr_size_t nbyte)
apr_bucketapr_bucket_heap_create (const char *buf, apr_size_t nbyte, void(*free_func)(void *data), apr_bucket_alloc_t *list)
apr_bucketapr_bucket_heap_make (apr_bucket *b, const char *buf, apr_size_t nbyte, void(*free_func)(void *data))
apr_bucketapr_bucket_pool_create (const char *buf, apr_size_t length, apr_pool_t *pool, apr_bucket_alloc_t *list)
apr_bucketapr_bucket_pool_make (apr_bucket *b, const char *buf, apr_size_t length, apr_pool_t *pool)
apr_bucketapr_bucket_mmap_create (apr_mmap_t *mm, apr_off_t start, apr_size_t length, apr_bucket_alloc_t *list)
apr_bucketapr_bucket_mmap_make (apr_bucket *b, apr_mmap_t *mm, apr_off_t start, apr_size_t length)
apr_bucketapr_bucket_socket_create (apr_socket_t *thissock, apr_bucket_alloc_t *list)
apr_bucketapr_bucket_socket_make (apr_bucket *b, apr_socket_t *thissock)
apr_bucketapr_bucket_pipe_create (apr_file_t *thispipe, apr_bucket_alloc_t *list)
apr_bucketapr_bucket_pipe_make (apr_bucket *b, apr_file_t *thispipe)
apr_bucketapr_bucket_file_create (apr_file_t *fd, apr_off_t offset, apr_size_t len, apr_pool_t *p, apr_bucket_alloc_t *list)
apr_bucketapr_bucket_file_make (apr_bucket *b, apr_file_t *fd, apr_off_t offset, apr_size_t len, apr_pool_t *p)
apr_status_t apr_bucket_file_enable_mmap (apr_bucket *b, int enabled)

Variables

const apr_bucket_type_t apr_bucket_type_flush
const apr_bucket_type_t apr_bucket_type_eos
const apr_bucket_type_t apr_bucket_type_file
const apr_bucket_type_t apr_bucket_type_heap
const apr_bucket_type_t apr_bucket_type_mmap
const apr_bucket_type_t apr_bucket_type_pool
const apr_bucket_type_t apr_bucket_type_pipe
const apr_bucket_type_t apr_bucket_type_immortal
const apr_bucket_type_t apr_bucket_type_transient
const apr_bucket_type_t apr_bucket_type_socket

Define Documentation

#define APR_BRIGADE_CHECK_CONSISTENCY (   b)

checks the ring pointers in a bucket brigade for consistency. an abort() will be triggered if any inconsistencies are found. note: this is a no-op unless APR_BUCKET_DEBUG is defined.

Parameters:
bThe brigade
#define APR_BRIGADE_CONCAT (   a,
 
)
Value:
do {                                    \
        APR_RING_CONCAT(&(a)->list, &(b)->list, apr_bucket, link);      \
        APR_BRIGADE_CHECK_CONSISTENCY((a));                             \
    } while (0)

Concatenate brigade b onto the end of brigade a, leaving brigade b empty

Parameters:
aThe first brigade
bThe second brigade
#define APR_BRIGADE_EMPTY (   b)    APR_RING_EMPTY(&(b)->list, apr_bucket, link)

Determine if the bucket brigade is empty

Parameters:
bThe brigade to check
Returns:
true or false
#define APR_BRIGADE_FIRST (   b)    APR_RING_FIRST(&(b)->list)

Return the first bucket in a brigade

Parameters:
bThe brigade to query
Returns:
The first bucket in the brigade
#define APR_BRIGADE_INSERT_HEAD (   b,
 
)
Value:
do {                            \
        apr_bucket *ap__b = (e);                                        \
        APR_RING_INSERT_HEAD(&(b)->list, ap__b, apr_bucket, link);      \
        APR_BRIGADE_CHECK_CONSISTENCY((b));                             \
    } while (0)

Insert a list of buckets at the front of a brigade

Parameters:
bThe brigade to add to
eThe first bucket in a list of buckets to insert
#define APR_BRIGADE_INSERT_TAIL (   b,
 
)
Value:
do {                            \
        apr_bucket *ap__b = (e);                                        \
        APR_RING_INSERT_TAIL(&(b)->list, ap__b, apr_bucket, link);      \
        APR_BRIGADE_CHECK_CONSISTENCY((b));                             \
    } while (0)

Insert a list of buckets at the end of a brigade

Parameters:
bThe brigade to add to
eThe first bucket in a list of buckets to insert
#define APR_BRIGADE_LAST (   b)    APR_RING_LAST(&(b)->list)

Return the last bucket in a brigade

Parameters:
bThe brigade to query
Returns:
The last bucket in the brigade
#define APR_BRIGADE_PREPEND (   a,
 
)
Value:
do {                                    \
        APR_RING_PREPEND(&(a)->list, &(b)->list, apr_bucket, link);     \
        APR_BRIGADE_CHECK_CONSISTENCY((a));                             \
    } while (0)

Prepend brigade b onto the beginning of brigade a, leaving brigade b empty

Parameters:
aThe first brigade
bThe second brigade
#define APR_BRIGADE_SENTINEL (   b)    APR_RING_SENTINEL(&(b)->list, apr_bucket, link)

Wrappers around the RING macros to reduce the verbosity of the code that handles bucket brigades. The magic pointer value that indicates the head of the brigade

Remarks:
This is used to find the beginning and end of the brigade, eg:
      while (e != APR_BRIGADE_SENTINEL(b)) {
          ...
          e = APR_BUCKET_NEXT(e);
      }
 
Parameters:
bThe brigade
Returns:
The magic pointer value
#define APR_BUCKET_ALLOC_SIZE   APR_ALIGN_DEFAULT(2*sizeof(apr_bucket_structs))

The amount that apr_bucket_alloc() should allocate in the common case. Note: this is twice as big as apr_bucket_structs to allow breathing room for third-party bucket types.

#define APR_BUCKET_BUFF_SIZE   8000

default bucket buffer size - 8KB minus room for memory allocator headers

#define APR_BUCKET_CHECK_CONSISTENCY (   e)

checks the brigade a bucket is in for ring consistency. an abort() will be triggered if any inconsistencies are found. note: this is a no-op unless APR_BUCKET_DEBUG is defined.

Parameters:
eThe bucket
#define apr_bucket_copy (   e,
 
)    (e)->type->copy(e, c)

Copy a bucket.

Parameters:
eThe bucket to copy
cReturns a pointer to the new bucket
#define apr_bucket_delete (   e)
Value:
do {                                    \
        APR_BUCKET_REMOVE(e);                                           \
        apr_bucket_destroy(e);                                          \
    } while (0)

Delete a bucket by removing it from its brigade (if any) and then destroying it.

Remarks:
This mainly acts as an aid in avoiding code verbosity. It is the preferred exact equivalent to:
      APR_BUCKET_REMOVE(e);
      apr_bucket_destroy(e);
 
Parameters:
eThe bucket to delete
#define apr_bucket_destroy (   e)
Value:
do {                                    \
        (e)->type->destroy((e)->data);                                  \
        (e)->free(e);                                                   \
    } while (0)

Free the resources used by a bucket. If multiple buckets refer to the same resource it is freed when the last one goes away.

See also:
apr_bucket_delete()
Parameters:
eThe bucket to destroy
#define APR_BUCKET_INIT (   e)    APR_RING_ELEM_INIT((e), link)

Initialize a new bucket's prev/next pointers

Parameters:
eThe bucket to initialize
#define APR_BUCKET_INSERT_AFTER (   a,
 
)
Value:
do {                            \
        apr_bucket *ap__a = (a), *ap__b = (b);                          \
        APR_RING_INSERT_AFTER(ap__a, ap__b, link);                      \
        APR_BUCKET_CHECK_CONSISTENCY(ap__a);                            \
    } while (0)

Insert a list of buckets after a specified bucket

Parameters:
aThe bucket to insert after
bThe buckets to insert
#define APR_BUCKET_INSERT_BEFORE (   a,
 
)
Value:
do {                            \
        apr_bucket *ap__a = (a), *ap__b = (b);                          \
        APR_RING_INSERT_BEFORE(ap__a, ap__b, link);                     \
        APR_BUCKET_CHECK_CONSISTENCY(ap__a);                            \
    } while (0)

Insert a list of buckets before a specified bucket

Parameters:
aThe bucket to insert before
bThe buckets to insert
#define APR_BUCKET_IS_EOS (   e)    ((e)->type == &apr_bucket_type_eos)

Determine if a bucket is an EOS bucket

Parameters:
eThe bucket to inspect
Returns:
true or false
#define APR_BUCKET_IS_FILE (   e)    ((e)->type == &apr_bucket_type_file)

Determine if a bucket is a FILE bucket

Parameters:
eThe bucket to inspect
Returns:
true or false
#define APR_BUCKET_IS_FLUSH (   e)    ((e)->type == &apr_bucket_type_flush)

Determine if a bucket is a FLUSH bucket

Parameters:
eThe bucket to inspect
Returns:
true or false
#define APR_BUCKET_IS_HEAP (   e)    ((e)->type == &apr_bucket_type_heap)

Determine if a bucket is a HEAP bucket

Parameters:
eThe bucket to inspect
Returns:
true or false
#define APR_BUCKET_IS_IMMORTAL (   e)    ((e)->type == &apr_bucket_type_immortal)

Determine if a bucket is a IMMORTAL bucket

Parameters:
eThe bucket to inspect
Returns:
true or false
#define APR_BUCKET_IS_METADATA (   e)    ((e)->type->is_metadata)

Determine if a bucket contains metadata. An empty bucket is safe to arbitrarily remove if and only if this is false.

Parameters:
eThe bucket to inspect
Returns:
true or false
#define APR_BUCKET_IS_MMAP (   e)    ((e)->type == &apr_bucket_type_mmap)

Determine if a bucket is a MMAP bucket

Parameters:
eThe bucket to inspect
Returns:
true or false
#define APR_BUCKET_IS_PIPE (   e)    ((e)->type == &apr_bucket_type_pipe)

Determine if a bucket is a PIPE bucket

Parameters:
eThe bucket to inspect
Returns:
true or false
#define APR_BUCKET_IS_POOL (   e)    ((e)->type == &apr_bucket_type_pool)

Determine if a bucket is a POOL bucket

Parameters:
eThe bucket to inspect
Returns:
true or false
#define APR_BUCKET_IS_SOCKET (   e)    ((e)->type == &apr_bucket_type_socket)

Determine if a bucket is a SOCKET bucket

Parameters:
eThe bucket to inspect
Returns:
true or false
#define APR_BUCKET_IS_TRANSIENT (   e)    ((e)->type == &apr_bucket_type_transient)

Determine if a bucket is a TRANSIENT bucket

Parameters:
eThe bucket to inspect
Returns:
true or false
#define APR_BUCKET_NEXT (   e)    APR_RING_NEXT((e), link)

Get the next bucket in the list

Parameters:
eThe current bucket
Returns:
The next bucket
#define APR_BUCKET_PREV (   e)    APR_RING_PREV((e), link)

Get the previous bucket in the list

Parameters:
eThe current bucket
Returns:
The previous bucket
#define apr_bucket_read (   e,
  str,
  len,
  block 
)    (e)->type->read(e, str, len, block)

Read some data from the bucket.

The apr_bucket_read function returns a convenient amount of data from the bucket provided, writing the address and length of the data to the pointers provided by the caller. The function tries as hard as possible to avoid a memory copy.

Buckets are expected to be a member of a brigade at the time they are read.

In typical application code, buckets are read in a loop, and after each bucket is read and processed, it is moved or deleted from the brigade and the next bucket read.

The definition of "convenient" depends on the type of bucket that is being read, and is decided by APR. In the case of memory based buckets such as heap and immortal buckets, a pointer will be returned to the location of the buffer containing the complete contents of the bucket.

Some buckets, such as the socket bucket, might have no concept of length. If an attempt is made to read such a bucket, the apr_bucket_read function will read a convenient amount of data from the socket. The socket bucket is magically morphed into a heap bucket containing the just-read data, and a new socket bucket is inserted just after this heap bucket.

To understand why apr_bucket_read might do this, consider the loop described above to read and process buckets. The current bucket is magically morphed into a heap bucket and returned to the caller. The caller processes the data, and deletes the heap bucket, moving onto the next bucket, the new socket bucket. This process repeats, giving the illusion of a bucket brigade that contains potentially infinite amounts of data. It is up to the caller to decide at what point to stop reading buckets.

Some buckets, such as the file bucket, might have a fixed size, but be significantly larger than is practical to store in RAM in one go. As with the socket bucket, if an attempt is made to read from a file bucket, the file bucket is magically morphed into a heap bucket containing a convenient amount of data read from the current offset in the file. During the read, the offset will be moved forward on the file, and a new file bucket will be inserted directly after the current bucket representing the remainder of the file. If the heap bucket was large enough to store the whole remainder of the file, no more file buckets are inserted, and the file bucket will disappear completely.

The pattern for reading buckets described above does create the illusion that the code is willing to swallow buckets that might be too large for the system to handle in one go. This however is just an illusion: APR will always ensure that large (file) or infinite (socket) buckets are broken into convenient bite sized heap buckets before data is returned to the caller.

There is a potential gotcha to watch for: if buckets are read in a loop, and aren't deleted after being processed, the potentially large bucket will slowly be converted into RAM resident heap buckets. If the file is larger than available RAM, an out of memory condition could be caused if the application is not careful to manage this.

Parameters:
eThe bucket to read from
strThe location to store a pointer to the data in
lenThe location to store the amount of data read
blockWhether the read function blocks
#define APR_BUCKET_REMOVE (   e)    APR_RING_REMOVE((e), link)

Remove a bucket from its bucket brigade

Parameters:
eThe bucket to remove
#define apr_bucket_setaside (   e,
 
)    (e)->type->setaside(e,p)

Setaside data so that stack data is not destroyed on returning from the function

Parameters:
eThe bucket to setaside
pThe pool to setaside into
#define apr_bucket_split (   e,
  point 
)    (e)->type->split(e, point)

Split one bucket in two at the point provided.

Once split, the original bucket becomes the first of the two new buckets.

(It is assumed that the bucket is a member of a brigade when this function is called).

Parameters:
eThe bucket to split
pointThe offset to split the bucket at

Typedef Documentation

Function called when a brigade should be flushed

typedef struct apr_bucket apr_bucket
See also:
apr_bucket

The one-sentence buzzword-laden overview: Bucket brigades represent a complex data stream that can be passed through a layered IO system without unnecessary copying. A longer overview follows...

A bucket brigade is a doubly linked list (ring) of buckets, so we aren't limited to inserting at the front and removing at the end. Buckets are only passed around as members of a brigade, although singleton buckets can occur for short periods of time.

Buckets are data stores of various types. They can refer to data in memory, or part of a file or mmap area, or the output of a process, etc. Buckets also have some type-dependent accessor functions: read, split, copy, setaside, and destroy.

read returns the address and size of the data in the bucket. If the data isn't in memory then it is read in and the bucket changes type so that it can refer to the new location of the data. If all the data doesn't fit in the bucket then a new bucket is inserted into the brigade to hold the rest of it.

split divides the data in a bucket into two regions. After a split the original bucket refers to the first part of the data and a new bucket inserted into the brigade after the original bucket refers to the second part of the data. Reference counts are maintained as necessary.

setaside ensures that the data in the bucket has a long enough lifetime. Sometimes it is convenient to create a bucket referring to data on the stack in the expectation that it will be consumed (output to the network) before the stack is unwound. If that expectation turns out not to be valid, the setaside function is called to move the data somewhere safer.

copy makes a duplicate of the bucket structure as long as it's possible to have multiple references to a single copy of the data itself. Not all bucket types can be copied.

destroy maintains the reference counts on the resources used by a bucket and frees them if necessary.

Note: all of the above functions have wrapper macros (apr_bucket_read(), apr_bucket_destroy(), etc), and those macros should be used rather than using the function pointers directly.

To write a bucket brigade, they are first made into an iovec, so that we don't write too little data at one time. Currently we ignore compacting the buckets into as few buckets as possible, but if we really want good performance, then we need to compact the buckets before we convert to an iovec, or possibly while we are converting to an iovec.

See also:
apr_bucket_brigade
See also:
apr_bucket_file
See also:
apr_bucket_heap
See also:
apr_bucket_mmap
See also:
apr_bucket_pool

Enumeration Type Documentation

Determines how a bucket or brigade should be read

Enumerator:
APR_BLOCK_READ 

block until data becomes available

APR_NONBLOCK_READ 

return immediately if no data is available


Function Documentation

apr_status_t apr_brigade_cleanup ( void *  data)

Empty out an entire bucket brigade. This includes destroying all of the buckets within the bucket brigade's bucket list. This is similar to apr_brigade_destroy(), except that it does not deregister the brigade's pool cleanup function.

Parameters:
dataThe bucket brigade to clean up
Remarks:
Generally, you should use apr_brigade_destroy(). This function can be useful in situations where you have a single brigade that you wish to reuse many times by destroying all of the buckets in the brigade and putting new buckets into it later.
apr_bucket_brigade* apr_brigade_create ( apr_pool_t p,
apr_bucket_alloc_t list 
)

Create a new bucket brigade. The bucket brigade is originally empty.

Parameters:
pThe pool to associate with the brigade. Data is not allocated out of the pool, but a cleanup is registered.
listThe bucket allocator to use
Returns:
The empty bucket brigade
apr_status_t apr_brigade_destroy ( apr_bucket_brigade b)

Destroy an entire bucket brigade. This includes destroying all of the buckets within the bucket brigade's bucket list.

Parameters:
bThe bucket brigade to destroy
apr_status_t apr_brigade_flatten ( apr_bucket_brigade bb,
char *  c,
apr_size_t *  len 
)

Take a bucket brigade and store the data in a flat char*

Parameters:
bbThe bucket brigade to create the char* from
cThe char* to write into
lenThe maximum length of the char array. On return, it is the actual length of the char array.
apr_bucket* apr_brigade_insert_file ( apr_bucket_brigade bb,
apr_file_t f,
apr_off_t  start,
apr_off_t  len,
apr_pool_t p 
)

Utility function to insert a file (or a segment of a file) onto the end of the brigade. The file is split into multiple buckets if it is larger than the maximum size which can be represented by a single bucket.

Parameters:
bbthe brigade to insert into
fthe file to insert
startthe offset of the start of the segment
lenthe length of the segment of the file to insert
ppool from which file buckets are allocated
Returns:
the last bucket inserted
apr_status_t apr_brigade_length ( apr_bucket_brigade bb,
int  read_all,
apr_off_t *  length 
)

Return the total length of the brigade.

Parameters:
bbThe brigade to compute the length of
read_allRead unknown-length buckets to force a size
lengthReturns the length of the brigade (up to the end, or up to a bucket read error), or -1 if the brigade has buckets of indeterminate length and read_all is 0.
apr_status_t apr_brigade_partition ( apr_bucket_brigade b,
apr_off_t  point,
apr_bucket **  after_point 
)

Partition a bucket brigade at a given offset (in bytes from the start of the brigade). This is useful whenever a filter wants to use known ranges of bytes from the brigade; the ranges can even overlap.

Parameters:
bThe brigade to partition
pointThe offset at which to partition the brigade
after_pointReturns a pointer to the first bucket after the partition
Returns:
APR_SUCCESS on success, APR_INCOMPLETE if the contents of the brigade were shorter than point, or an error code.
Remarks:
if APR_INCOMPLETE is returned, after_point will be set to the brigade sentinel.
apr_status_t apr_brigade_pflatten ( apr_bucket_brigade bb,
char **  c,
apr_size_t *  len,
apr_pool_t pool 
)

Creates a pool-allocated string representing a flat bucket brigade

Parameters:
bbThe bucket brigade to create the char array from
cOn return, the allocated char array
lenOn return, the length of the char array.
poolThe pool to allocate the string from.
apr_status_t apr_brigade_printf ( apr_bucket_brigade b,
apr_brigade_flush  flush,
void *  ctx,
const char *  fmt,
  ... 
)

Evaluate a printf and put the resulting string at the end of the bucket brigade.

Parameters:
bThe brigade to write to
flushThe flush function to use if the brigade is full
ctxThe structure to pass to the flush function
fmtThe format of the string to write
...The arguments to fill out the format
Returns:
APR_SUCCESS or error code
apr_status_t apr_brigade_putc ( apr_bucket_brigade b,
apr_brigade_flush  flush,
void *  ctx,
const char  c 
)

This function writes a character into a bucket brigade.

Parameters:
bThe bucket brigade to add to
flushThe flush function to use if the brigade is full
ctxThe structure to pass to the flush function
cThe character to add
Returns:
APR_SUCCESS or error code
apr_status_t apr_brigade_puts ( apr_bucket_brigade bb,
apr_brigade_flush  flush,
void *  ctx,
const char *  str 
)

This function writes a string into a bucket brigade.

Parameters:
bbThe bucket brigade to add to
flushThe flush function to use if the brigade is full
ctxThe structure to pass to the flush function
strThe string to add
Returns:
APR_SUCCESS or error code
apr_status_t apr_brigade_putstrs ( apr_bucket_brigade b,
apr_brigade_flush  flush,
void *  ctx,
  ... 
)

This function writes an unspecified number of strings into a bucket brigade.

Parameters:
bThe bucket brigade to add to
flushThe flush function to use if the brigade is full
ctxThe structure to pass to the flush function
...The strings to add. The final string must be NULL
Returns:
APR_SUCCESS or error code
apr_bucket_brigade* apr_brigade_split ( apr_bucket_brigade b,
apr_bucket e 
)

Create a new bucket brigade and move the buckets from the tail end of an existing brigade into the new brigade. Buckets from

Parameters:
eto the last bucket (inclusively) of brigade
bare moved from
bto the returned brigade.
bThe brigade to split
eThe first bucket to move
Returns:
The new brigade
Warning:
Note that this function always allocates a new brigade so memory consumption should be carefully considered.
apr_bucket_brigade* apr_brigade_split_ex ( apr_bucket_brigade b,
apr_bucket e,
apr_bucket_brigade a 
)

Move the buckets from the tail end of the existing brigade b into the brigade a. If a is NULL a new brigade is created. Buckets from e to the last bucket (inclusively) of brigade b are moved from b to the returned brigade a.

Parameters:
bThe brigade to split
eThe first bucket to move
aThe brigade which should be used for the result or NULL if a new brigade should be created.
Returns:
The brigade supplied in
Parameters:
aor a new one if
awas NULL.
Warning:
Note that this function allocates a new brigade if
Parameters:
ais NULL so memory consumption should be carefully considered.
apr_status_t apr_brigade_split_line ( apr_bucket_brigade bbOut,
apr_bucket_brigade bbIn,
apr_read_type_e  block,
apr_off_t  maxbytes 
)

Split a brigade to represent one LF line.

Parameters:
bbOutThe bucket brigade that will have the LF line appended to.
bbInThe input bucket brigade to search for a LF-line.
blockThe blocking mode to be used to split the line.
maxbytesThe maximum bytes to read. If this many bytes are seen without a LF, the brigade will contain a partial line.
apr_status_t apr_brigade_to_iovec ( apr_bucket_brigade b,
struct iovec *  vec,
int *  nvec 
)

Create an iovec of the elements in a bucket_brigade... return number of elements used. This is useful for writing to a file or to the network efficiently.

Parameters:
bThe bucket brigade to create the iovec from
vecThe iovec to create
nvecThe number of elements in the iovec. On return, it is the number of iovec elements actually filled out.
apr_status_t apr_brigade_vprintf ( apr_bucket_brigade b,
apr_brigade_flush  flush,
void *  ctx,
const char *  fmt,
va_list  va 
)

Evaluate a printf and put the resulting string at the end of the bucket brigade.

Parameters:
bThe brigade to write to
flushThe flush function to use if the brigade is full
ctxThe structure to pass to the flush function
fmtThe format of the string to write
vaThe arguments to fill out the format
Returns:
APR_SUCCESS or error code
apr_status_t apr_brigade_vputstrs ( apr_bucket_brigade b,
apr_brigade_flush  flush,
void *  ctx,
va_list  va 
)

This function writes a list of strings into a bucket brigade.

Parameters:
bThe bucket brigade to add to
flushThe flush function to use if the brigade is full
ctxThe structure to pass to the flush function
vaA list of strings to add
Returns:
APR_SUCCESS or error code.
apr_status_t apr_brigade_write ( apr_bucket_brigade b,
apr_brigade_flush  flush,
void *  ctx,
const char *  str,
apr_size_t  nbyte 
)

This function writes a string into a bucket brigade.

The apr_brigade_write function attempts to be efficient with the handling of heap buckets. Regardless of the amount of data stored inside a heap bucket, heap buckets are a fixed size to promote their reuse.

If an attempt is made to write a string to a brigade that already ends with a heap bucket, this function will attempt to pack the string into the remaining space in the previous heap bucket, before allocating a new heap bucket.

This function always returns APR_SUCCESS, unless a flush function is passed, in which case the return value of the flush function will be returned if used.

Parameters:
bThe bucket brigade to add to
flushThe flush function to use if the brigade is full
ctxThe structure to pass to the flush function
strThe string to add
nbyteThe number of bytes to write
Returns:
APR_SUCCESS or error code
apr_status_t apr_brigade_writev ( apr_bucket_brigade b,
apr_brigade_flush  flush,
void *  ctx,
const struct iovec *  vec,
apr_size_t  nvec 
)

This function writes multiple strings into a bucket brigade.

Parameters:
bThe bucket brigade to add to
flushThe flush function to use if the brigade is full
ctxThe structure to pass to the flush function
vecThe strings to add (address plus length for each)
nvecThe number of entries in iovec
Returns:
APR_SUCCESS or error code
void* apr_bucket_alloc ( apr_size_t  size,
apr_bucket_alloc_t list 
)

Allocate memory for use by the buckets.

Parameters:
sizeThe amount to allocate.
listThe allocator from which to allocate the memory.
apr_bucket_alloc_t* apr_bucket_alloc_create ( apr_pool_t p)

Create a bucket allocator.

Parameters:
pThis pool's underlying apr_allocator_t is used to allocate memory for the bucket allocator. When the pool is destroyed, the bucket allocator's cleanup routine will free all memory that has been allocated from it.
Remarks:
The reason the allocator gets its memory from the pool's apr_allocator_t rather than from the pool itself is because the bucket allocator will free large memory blocks back to the allocator when it's done with them, thereby preventing memory footprint growth that would occur if we allocated from the pool.
Warning:
The allocator must never be used by more than one thread at a time.
apr_bucket_alloc_t* apr_bucket_alloc_create_ex ( apr_allocator_t allocator)

Create a bucket allocator.

Parameters:
allocatorThis apr_allocator_t is used to allocate both the bucket allocator and all memory handed out by the bucket allocator. The caller is responsible for destroying the bucket allocator and the apr_allocator_t -- no automatic cleanups will happen.
Warning:
The allocator must never be used by more than one thread at a time.
void apr_bucket_alloc_destroy ( apr_bucket_alloc_t list)

Destroy a bucket allocator.

Parameters:
listThe allocator to be destroyed
apr_status_t apr_bucket_copy_notimpl ( apr_bucket e,
apr_bucket **  c 
)

A place holder function that signifies that the copy function was not implemented for this bucket

Parameters:
eThe bucket to copy
cReturns a pointer to the new bucket
Returns:
APR_ENOTIMPL
void apr_bucket_destroy_noop ( void *  data)

A place holder function that signifies that this bucket does not need to do anything special to be destroyed. That's only the case for buckets that either have no data (metadata buckets) or buckets whose data pointer points to something that's not a bucket-type-specific structure, as with simple buckets where data points to a string and pipe buckets where data points directly to the apr_file_t.

Parameters:
dataThe bucket data to destroy
apr_bucket* apr_bucket_eos_create ( apr_bucket_alloc_t list)

Create an End of Stream bucket. This indicates that there is no more data coming from down the filter stack. All filters should flush at this point.

Parameters:
listThe freelist from which this bucket should be allocated
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_eos_make ( apr_bucket b)

Make the bucket passed in an EOS bucket. This indicates that there is no more data coming from down the filter stack. All filters should flush at this point.

Parameters:
bThe bucket to make into an EOS bucket
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_file_create ( apr_file_t fd,
apr_off_t  offset,
apr_size_t  len,
apr_pool_t p,
apr_bucket_alloc_t list 
)

Create a bucket referring to a file.

Parameters:
fdThe file to put in the bucket
offsetThe offset where the data of interest begins in the file
lenThe amount of data in the file we are interested in
pThe pool into which any needed structures should be created while reading from this file bucket
listThe freelist from which this bucket should be allocated
Returns:
The new bucket, or NULL if allocation failed
Remarks:
If the file is truncated such that the segment of the file referenced by the bucket no longer exists, an attempt to read from the bucket will fail with APR_EOF.
apr_brigade_insert_file() should generally be used to insert files into brigades, since that function can correctly handle large file issues.
apr_status_t apr_bucket_file_enable_mmap ( apr_bucket b,
int  enabled 
)

Enable or disable memory-mapping for a FILE bucket (default is enabled)

Parameters:
bThe bucket
enabledWhether memory-mapping should be enabled
Returns:
APR_SUCCESS normally, or an error code if the operation fails
apr_bucket* apr_bucket_file_make ( apr_bucket b,
apr_file_t fd,
apr_off_t  offset,
apr_size_t  len,
apr_pool_t p 
)

Make the bucket passed in a bucket refer to a file

Parameters:
bThe bucket to make into a FILE bucket
fdThe file to put in the bucket
offsetThe offset where the data of interest begins in the file
lenThe amount of data in the file we are interested in
pThe pool into which any needed structures should be created while reading from this file bucket
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_flush_create ( apr_bucket_alloc_t list)

Create a flush bucket. This indicates that filters should flush their data. There is no guarantee that they will flush it, but this is the best we can do.

Parameters:
listThe freelist from which this bucket should be allocated
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_flush_make ( apr_bucket b)

Make the bucket passed in a FLUSH bucket. This indicates that filters should flush their data. There is no guarantee that they will flush it, but this is the best we can do.

Parameters:
bThe bucket to make into a FLUSH bucket
Returns:
The new bucket, or NULL if allocation failed
void apr_bucket_free ( void *  block)

Free memory previously allocated with apr_bucket_alloc().

Parameters:
blockThe block of memory to be freed.
apr_bucket* apr_bucket_heap_create ( const char *  buf,
apr_size_t  nbyte,
void(*)(void *data)  free_func,
apr_bucket_alloc_t list 
)

Create a bucket referring to memory on the heap. If the caller asks for the data to be copied, this function always allocates 4K of memory so that more data can be added to the bucket without requiring another allocation. Therefore not all the data may be put into the bucket. If copying is not requested then the bucket takes over responsibility for free()ing the memory.

Parameters:
bufThe buffer to insert into the bucket
nbyteThe size of the buffer to insert.
free_funcFunction to use to free the data; NULL indicates that the bucket should make a copy of the data
listThe freelist from which this bucket should be allocated
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_heap_make ( apr_bucket b,
const char *  buf,
apr_size_t  nbyte,
void(*)(void *data)  free_func 
)

Make the bucket passed in a bucket refer to heap data

Parameters:
bThe bucket to make into a HEAP bucket
bufThe buffer to insert into the bucket
nbyteThe size of the buffer to insert.
free_funcFunction to use to free the data; NULL indicates that the bucket should make a copy of the data
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_immortal_create ( const char *  buf,
apr_size_t  nbyte,
apr_bucket_alloc_t list 
)

Create a bucket referring to long-lived data.

Parameters:
bufThe data to insert into the bucket
nbyteThe size of the data to insert.
listThe freelist from which this bucket should be allocated
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_immortal_make ( apr_bucket b,
const char *  buf,
apr_size_t  nbyte 
)

Make the bucket passed in a bucket refer to long-lived data

Parameters:
bThe bucket to make into a IMMORTAL bucket
bufThe data to insert into the bucket
nbyteThe size of the data to insert.
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_mmap_create ( apr_mmap_t mm,
apr_off_t  start,
apr_size_t  length,
apr_bucket_alloc_t list 
)

Create a bucket referring to mmap()ed memory.

Parameters:
mmThe mmap to insert into the bucket
startThe offset of the first byte in the mmap that this bucket refers to
lengthThe number of bytes referred to by this bucket
listThe freelist from which this bucket should be allocated
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_mmap_make ( apr_bucket b,
apr_mmap_t mm,
apr_off_t  start,
apr_size_t  length 
)

Make the bucket passed in a bucket refer to an MMAP'ed file

Parameters:
bThe bucket to make into a MMAP bucket
mmThe mmap to insert into the bucket
startThe offset of the first byte in the mmap that this bucket refers to
lengthThe number of bytes referred to by this bucket
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_pipe_create ( apr_file_t thispipe,
apr_bucket_alloc_t list 
)

Create a bucket referring to a pipe.

Parameters:
thispipeThe pipe to put in the bucket
listThe freelist from which this bucket should be allocated
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_pipe_make ( apr_bucket b,
apr_file_t thispipe 
)

Make the bucket passed in a bucket refer to a pipe

Parameters:
bThe bucket to make into a PIPE bucket
thispipeThe pipe to put in the bucket
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_pool_create ( const char *  buf,
apr_size_t  length,
apr_pool_t pool,
apr_bucket_alloc_t list 
)

Create a bucket referring to memory allocated from a pool.

Parameters:
bufThe buffer to insert into the bucket
lengthThe number of bytes referred to by this bucket
poolThe pool the memory was allocated from
listThe freelist from which this bucket should be allocated
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_pool_make ( apr_bucket b,
const char *  buf,
apr_size_t  length,
apr_pool_t pool 
)

Make the bucket passed in a bucket refer to pool data

Parameters:
bThe bucket to make into a pool bucket
bufThe buffer to insert into the bucket
lengthThe number of bytes referred to by this bucket
poolThe pool the memory was allocated from
Returns:
The new bucket, or NULL if allocation failed
apr_status_t apr_bucket_setaside_noop ( apr_bucket data,
apr_pool_t pool 
)

This function simply returns APR_SUCCESS to denote that the bucket does not require anything to happen for its setaside() function. This is appropriate for buckets that have "immortal" data -- the data will live at least as long as the bucket.

Parameters:
dataThe bucket to setaside
poolThe pool defining the desired lifetime of the bucket data
Returns:
APR_SUCCESS
apr_status_t apr_bucket_setaside_notimpl ( apr_bucket data,
apr_pool_t pool 
)

A place holder function that signifies that the setaside function was not implemented for this bucket

Parameters:
dataThe bucket to setaside
poolThe pool defining the desired lifetime of the bucket data
Returns:
APR_ENOTIMPL
apr_status_t apr_bucket_shared_copy ( apr_bucket a,
apr_bucket **  b 
)

Copy a refcounted bucket, incrementing the reference count. Most reference-counting bucket types will be able to use this function as their copy function without any additional type-specific handling.

Parameters:
aThe bucket to copy
bReturns a pointer to the new bucket
Returns:
APR_ENOMEM if allocation failed; or APR_SUCCESS
int apr_bucket_shared_destroy ( void *  data)

Decrement the refcount of the data in the bucket. This function should only be called by type-specific bucket destruction functions.

Parameters:
dataThe private data pointer from the bucket to be destroyed
Returns:
TRUE or FALSE; TRUE if the reference count is now zero, indicating that the shared resource itself can be destroyed by the caller.
apr_bucket* apr_bucket_shared_make ( apr_bucket b,
void *  data,
apr_off_t  start,
apr_size_t  length 
)

Initialize a bucket containing reference-counted data that may be shared. The caller must allocate the bucket if necessary and initialize its type-dependent fields, and allocate and initialize its own private data structure. This function should only be called by type-specific bucket creation functions.

Parameters:
bThe bucket to initialize
dataA pointer to the private data structure with the reference count at the start
startThe start of the data in the bucket relative to the private base pointer
lengthThe length of the data in the bucket
Returns:
The new bucket, or NULL if allocation failed
apr_status_t apr_bucket_shared_split ( apr_bucket b,
apr_size_t  point 
)

Split a bucket into two at the given point, and adjust the refcount to the underlying data. Most reference-counting bucket types will be able to use this function as their split function without any additional type-specific handling.

Parameters:
bThe bucket to be split
pointThe offset of the first byte in the new bucket
Returns:
APR_EINVAL if the point is not within the bucket; APR_ENOMEM if allocation failed; or APR_SUCCESS
apr_status_t apr_bucket_simple_copy ( apr_bucket a,
apr_bucket **  b 
)

Copy a simple bucket. Most non-reference-counting buckets that allow multiple references to the same block of data (eg transient and immortal) will use this as their copy function without any additional type-specific handling.

Parameters:
aThe bucket to copy
bReturns a pointer to the new bucket
Returns:
APR_ENOMEM if allocation failed; or APR_SUCCESS
apr_status_t apr_bucket_simple_split ( apr_bucket b,
apr_size_t  point 
)

Split a simple bucket into two at the given point. Most non-reference counting buckets that allow multiple references to the same block of data (eg transient and immortal) will use this as their split function without any additional type-specific handling.

Parameters:
bThe bucket to be split
pointThe offset of the first byte in the new bucket
Returns:
APR_EINVAL if the point is not within the bucket; APR_ENOMEM if allocation failed; or APR_SUCCESS
apr_bucket* apr_bucket_socket_create ( apr_socket_t thissock,
apr_bucket_alloc_t list 
)

Create a bucket referring to a socket.

Parameters:
thissockThe socket to put in the bucket
listThe freelist from which this bucket should be allocated
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_socket_make ( apr_bucket b,
apr_socket_t thissock 
)

Make the bucket passed in a bucket refer to a socket

Parameters:
bThe bucket to make into a SOCKET bucket
thissockThe socket to put in the bucket
Returns:
The new bucket, or NULL if allocation failed
apr_status_t apr_bucket_split_notimpl ( apr_bucket data,
apr_size_t  point 
)

A place holder function that signifies that the split function was not implemented for this bucket

Parameters:
dataThe bucket to split
pointThe location to split the bucket
Returns:
APR_ENOTIMPL
apr_bucket* apr_bucket_transient_create ( const char *  buf,
apr_size_t  nbyte,
apr_bucket_alloc_t list 
)

Create a bucket referring to data on the stack.

Parameters:
bufThe data to insert into the bucket
nbyteThe size of the data to insert.
listThe freelist from which this bucket should be allocated
Returns:
The new bucket, or NULL if allocation failed
apr_bucket* apr_bucket_transient_make ( apr_bucket b,
const char *  buf,
apr_size_t  nbyte 
)

Make the bucket passed in a bucket refer to stack data

Parameters:
bThe bucket to make into a TRANSIENT bucket
bufThe data to insert into the bucket
nbyteThe size of the data to insert.
Returns:
The new bucket, or NULL if allocation failed

Variable Documentation

The EOS bucket type. This signifies that there will be no more data, ever. All filters MUST send all data to the next filter when they receive a bucket of this type

The FILE bucket type. This bucket represents a file on disk

There is no apr_bucket_destroy_notimpl, because destruction is required to be implemented (it could be a noop, but only if that makes sense for the bucket type) The flush bucket type. This signifies that all data should be flushed to the next filter. The flush bucket should be sent with the other buckets.

The HEAP bucket type. This bucket represents a data allocated from the heap.

The IMMORTAL bucket type. This bucket represents a segment of data that the creator is willing to take responsibility for. The core will do nothing with the data in an immortal bucket

The MMAP bucket type. This bucket represents an MMAP'ed file

The PIPE bucket type. This bucket represents a pipe to another program.

The POOL bucket type. This bucket represents a data that was allocated from a pool. IF this bucket is still available when the pool is cleared, the data is copied on to the heap.

The SOCKET bucket type. This bucket represents a socket to another machine

The TRANSIENT bucket type. This bucket represents a data allocated off the stack. When the setaside function is called, this data is copied on to the heap

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